Symposium Organizers
Mark A. Shannon University of Illinois, Urbana-Champaign
David Ginley National Renewable Energy Laboratory
Alan M. Weiss Global Water Group
JJ1: Materials for Water Treatment
Session Chairs
Tuesday PM, April 18, 2006
Room 2022 (Moscone West)
9:30 AM - **JJ1.1
The Mexican Cactus as a New Environmentally Benign Material for the Removal of Contaminants in Drinking Water.
Kevin Young 1 , Alessandro Anzalone 1 , Norma Alcantar 1
1 Chemical Engineering, University of South Florida, Tampa, Florida, United States
Show AbstractThe contamination of water supplies in different Mexican communities by particulates and heavy metals is becoming a largely recognized problem facing Mexican governments and citizens. We show that a common Mexican cactus produces a gum-like substance, cactus mucilage, which shows excellent flocculating abilities and is an economically viable alternative for low income communities. The use of natural environmentally benign agents such as mucilage in the treatment of drinking water is rapidly gaining interest due to their inherently renewable character and low toxicity. Combining these advantages and the cultural advantages of using a Mexican cactus, we are developing a sustainable water treatment technology. Cactus mucilage is a neutral mixture of approximately 55 high-molecular weight sugar residues composed basically of arabinose, galactose, rhamnose, xylose, and galacturonic acid. We show how this natural product was characterized for its use as a flocculating agent as well as the mucilage efficiency for reducing arsenic and particulates from drinking water as determined by light scattering, Atomic Absorption and Infrared Spectroscopy. The arsenic concentration of drinking water samples was analyzed using hydride generation-atomic fluorescence spectrometry. Flocculation studies proved the mucilage to be a much faster flocculating agent when compared to Al2(SO4)3, and this efficiency increases with mucilage concentration. Jar tests revealed that lower concentrations of mucilage provided the optimal effectiveness for supernatant clarity, an important factor in determining the potability of water. At lease 50% removal of arsenic can be obtained from solutions with original arsenic concentration ranging between 20 and 500 ppm by using the mucilage. It was also found that removal grades could be optimized by judiciously varying the residence time and height of the separation column to obtain >98% arsenic removal. Initial filter results with the mucilage embedded in a silica matrix as well as different mucilage dosing schemes prove the feasibility of applying this technology as a domestic method for heavy metal removal. This project provides fundamental, quantitative insights into the necessary and minimum requirements for a sustainable natural material used as flocculating agents that are innovative, environmentally benign, cost-effective, and culturally sensitive.
10:00 AM - JJ1.2
Nanoporous Electrodialysis Membranes for Treatment of Brackish Water.
William Bourcier 1 , Kevin O'Brien 3 , Jeffrey Haslam 3 , Sonia Letant 2 , Kevin Langry 2 , Charlene Schaldach 2 , Thomas Felter 2 , William Wilson 2
1 Energy and Environment, Lawrence Livermore Lab, Livermore, California, United States, 3 Engineering, Lawrence Livermore Lab, Livermore, California, United States, 2 Chemistry and Material Science, Lawrence Livermore Lab, Livermore, California, United States
Show AbstractWe have demonstrated the use of nanoporous membranes in electrodialysis for removal of salt from brackish waters. Pores with diameters less than about 15 nm immersed in waters of moderate TDS occur in a double layer overlapped condition and preferentially allow passage of ions opposite in charge to the membrane surface. When placed in an electrostatic field, pairs of membranes of negative and positive charge provide the permselectvity needed to remove salt from water. We have demonstrated the use of ion-track etched polycarbonate membranes for this application. Polycarbonate has an intrinsic negative surface charge at near-neutral pH and therefore functions as a cation membrane. The polycarbonate is functionalized to produce a positive charge to achieve anion selectivity. Furthermore, the membranes can be functionalized with specific groups to allow selective transport, for example of nitrate ions, in order to treat marginally impaired waters in which selective extraction of contaminants is desired. The use of nanoporous membranes in electrodialysis has the potential to be much more energy efficient and species selective than electrodialysis using conventional solid polymer membranes.
10:15 AM - JJ1.3
Energetics and Structure of Organic- and Bio-Molecules at Solid Surfaces: an Experimental and Molecular Modeling Study of Carboxylic Species on Layered Double Hydroxides.
R. James Kirkpatrick 1 2 , P. Kumar Padma 1 , Andrey Kalinichev 1 2 , Marc Reinholdt 1 , Qiang Li 1
1 Department of Geology, Univ. of Illinois, Urbana, Illinois, United States, 2 WaterCAMPwS, Univ. of Illinois, Urbana, Illinois, United States
Show Abstract10:30 AM - JJ1.4
Membrane Fouling and Membrane Cleaning in Anaerobic Membrane Bioreactors.
Petia Tontcheva 1 , Amily Zhang 1 , Sudini Padmasiri 1 , Mark Fitch 2 , Birgir Norddahl 3 , Lutgarde Raskin 4 1 , Eberhard Morgenroth 1
1 Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 2 Department of Civil, Architectural & Environmental Engineering, University of Missouri-Rolla, Rolla, Missouri, United States, 3 TUFCO, Technical Development and Research Centre Odense, University of Southern Denmark, Odense Denmark, 4 Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, Michigan, United States
Show AbstractINTRODUCTION. Process economics and performance of membrane bioreactors (MBR) depends on finding efficient ways to reduce membrane fouling and to optimize membrane cleaning. Most application and research on MBRs has in the past focused on aerobic systems where fouling is usually attributed to sorption of soluble and colloidal organic matter to the membrane material. In anaerobic MBRs, it has been shown that organic fouling can occur in combination with inorganic fouling resulting from precipitation. The current work evaluates the influence of membrane history and cleaning frequency on membrane performance in an anaerobic MBR.MATERIALS AND METHODS. A tubular polyethersulphone ultrafiltration membrane (Weir Envig, Paarl, South Africa) was used in a six-liter AnMBR. The reactor was fed with a concentrated waste stream at a loading rate of 1.0-3.0 g VS/l d and a hydraulic retention time of 6 days. The main membrane was 12 mm in diameter and 1 m in length with a molecular weight cut off of 20,000 Daltons. Four 10-cm test membrane modules were integrated in the recirculation to allow for an independent evaluation of cleaning and fouling. During normal reactor operation, the transmembrane pressure was maintained at 20-70 kPa and the cross flow velocities of 1.5 - 1.9 m/s.Membrane fouling and cleaning were evaluated in the AnMBR and also in an identical setup for flux measurements using deionized (DI) water or filtered permeate (FP). Fouling was visualized on the membrane surface after cryosectioning of a cross sections using scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) (FEI Company, Philips XL30 ESEM-FEG). Membranes were operated either without any chemical cleaning or with monthly or weekly chemical cleaning.Other polymeric membrane materials developed in the lab of Prof. Mayes (MIT) will be tested side by side with current polyethersulphone membranes and results will be compared.RESULTS AND CONCLUSIONS. Chemical cleaning was not able to fully recover the clean water flux. The irreversible resistance that could not be removed using HNO3 cleaning was 1.3 times the membrane resistance. Cleaning efficiency was not significantly influenced by membrane history (i.e., long-term operation without any chemical cleaning) or cleaning frequency (weekly or monthly). The observed fouling layer was a combination of organic and inorganic fouling. The interactions between organic foulants and inorganic precipitation and their relative contribution to the observed flux decline are not well understood. Future work will focus on evaluating the specific mechanism leading to fouling and to what extent fouling can be prevented or removed using novel membrane materials or reactor operation.
10:45 AM - JJ1.5
The Influence of Shear on Floc Structure Development and Membrane Fouling Potential in Membrane Bioreactors
Adrienne Menniti 1 , Eberhard Morgenroth 1
1 Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
Show Abstract11:30 AM - **JJ1.6
Clathrate Hydrates for Production of Potable Water.
Robert Bradshaw 1 , Blake Simmons 1 , Eric Majzoub 1 , W Clift 1 , Daniel Dedrick 1
1 , Sandia National Laboratories, Livermore, California, United States
Show AbstractClathrate hydrates are crystalline inclusion compounds of water and a guest molecule (e.g., methane) that form at temperatures below ambient but above the freezing point of water. There are three known crystalline structures of hydrates (structure I, II, and H) in which cavities within the hydrogen bonded water molecule lattice trap the hydrate-forming species. The clathrate structure excludes dissolved solutes, such as sodium chloride, from the aqueous phase and thereby offers a possible means to produce potable water from seawater or brackish water. The concept of using clathrate hydrates for desalination is not new. However, before clathrate hydrate desalination becomes a viable technology, fundamental issues of controlled hydrate formation, hydrate size and morphology, agglomeration, amount of entrapped salt, and the efficient recovery of hydrates must be understood. This paper will report structural characterization of hydrates formed with several guest molecules over a wide range of conditions in an attempt to further the physicochemical insight needed to address these issues. Clathrate hydrate formation experiments were performed using a variety of host molecules, including R141b, a commercial refrigerant, C2FCl2H3. Hydrates of R141b were formed at temperatures from 2°C to 6°C and atmospheric pressure from deionized water and 2% - 7% NaCl solutions. Samples of the hydrates were characterized by cold-stage x-ray diffraction and Raman spectroscopy and determined to be structure II. Additional experiments were conducted with a gaseous hydrate former, ethylene, which readily formed hydrates with deionized or saline water at 2°C and several atmospheres of pressure. Experiments with several other hydrate forming molecules were conducted and the results obtained from their structural characterization will be reported. We will also present proof-of-concept experiments demonstrating a novel technique of desalination using these hydrate formers.Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin company, for the United States Department of Energy under contract DE-AC04-94AL85000.
12:00 PM - JJ1.7
High Flux Polyamide Composite Hollow Fiber Membranes for Reverse Osmosis Applications.
Ian Norris 1 , Malcolm Morrison 1 , Benjamin Mattes 1
1 , Santa Fe Science and Technology, Santa Fe, New Mexico, United States
Show AbstractAlthough hollow fiber membrane elements provide a higher surface area/volume (4 to 10X improvement) than that achievable in a spiral wound membrane element, commercial reverse osmosis elements for both brackish water and seawater desalination are manufactured in the spiral wound configuration. This is because the current generation of composite membranes has slightly higher salt rejections and an order of magnitude higher water flux than the current generation of asymmetric linear polyamide hollow fiber membranes. As a result, the field of reverse osmosis has overwhelmingly moved in the direction of interfacially synthesized membranes, which has been dominated by polyamide composite flat-sheet membranes. To overcome the low flux of current hollow fiber membranes, we have developed composite hollow fiber membranes based on the interfacial polymerization of a cross-linked polyamide layer onto a semi-permeable hollow fiber support which exploit the advantages of using a thin-film composite reverse osmosis membrane (higher flux and salt rejection) with the higher surface area/volume ratio of hollow fiber modules. Since ultra-filtration hollow fiber supports that could withstand the feed pressures required for reverse osmosis applications without collapsing are not commercially available, we developed polysulfone hollow fibers in-house for use as the support membrane. The polysulfone hollow fiber supports that were developed in-house had an outer diameter of 380 microns, a pure water permeability of 90 L/m2.day.psi, a pore size < 10 nm and a collapse pressure > 1,100 psi. These hollow fiber supports were then coated with a polyamide salt rejecting layer based on the interfacial polymerization reaction between m-phenylenediame and trimesoyl chloride. The process for producing defect-free composite hollow fiber membranes was found to be more complex than that for fabricating composite flat-sheet membranes since we cannot directly implement the procedures developed for the fabrication of composite polyamide flat-sheet membranes due to the three dimensional nature of the hollow fiber support (e.g. removal of the excess aqueous solution using a rubber roller). The best figures-of-merit obtained for these composite polyamide hollow fiber membranes for the desalination of a synthetic brackish water feed (2,000 ppm NaCl) at a feed pressure of 225 psi were a water flux of 440 L/m2.day and a salt rejection of 99.1%. Based on the water flux and packing density of the hollow membrane, it is estimated that productivity of a hollow fiber membrane element using these new composite membranes will be between 40 and 50% greater than that of a similar sized spiral wound brackish water membrane element.
12:15 PM - JJ1.8
Polyion-amphiphile Surfaces and Coagulants for Water Treatment.
May Nyman 1 , Jill Bieker 1 , Joel Bixler 1 , Michael Kent 1
1 , Sandia National Laboratories, Albuquerque, New Mexico, United States
Show AbstractInorganic polyions such as aluminum polycations and polyoxometalate anions have a well-known capability of binding biomolecules, predominantly through electrostatic interactions. We are currently investigating the exploitation of these material characteristics for removal of pathogens from domestic water sources; through selective attachment of pathogens to functionalized surfaces (filtration media) or by coagulation technologies. The polyion serves to bind the pathogenic species; and the amphiphile enables precipitation of the pathogen-cluster in the case of coagulant chemistry, and lends aqueous insolubility and hydrophobicity to the functionalized surfaces. Functionalized surfaces were prepared by coating glass beads and surface affinity studies were carried out for both bacterial (bacillus) and viral (bovine rotavirus and influenza A) species. Selectivity and affinity of the species for the surfaces are discussed in terms of chemical and structural characteristics of the coatings. Coagulation studies were carried out with bovine rotavirus and influenza A. Removal of these species from water is similarly discussed in terms of the various coagulant chemistries investigated. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94Al85000.
JJ2: Materials Synthesis for Water Treatment
Session Chairs
Tuesday PM, April 18, 2006
Room 2022 (Moscone West)
2:30 PM - **JJ2.1
High Flux, Anti-fouling Polymer Membranes from Self-assembling Graft Copolymers.
Anne Mayes 1 , Ayse Asatekin 2 , Long-Hua Lee 2
1 Department of Materials Science and Engineering, MIT, Cambridge, Massachusetts, United States, 2 Department of Chemical Engineering, MIT, Cambridge, Massachusetts, United States
Show AbstractPolymer membranes used for water filtration commonly suffer from fouling associated with their hydrophobic or charged surface chemistries. Submerged membrane bioreactors (MBRs) offer a particularly challenging environment for porous ultrafiltration (UF) membranes due to high concentrations of dissolved or suspended biological molecules and microorganisms, which can plug pores leading to rapid flux decline. To address fouling and flux limitations in water treatment, polymer filtration membranes incorporating amphiphilic graft copolymers have been developed consisting of a poly(vinylidene fluoride) (PVDF) backbone and polyoxyethylene methacrylate (POEM) side chains, PVDF-g-POEM. These materials molecularly self-assemble into bicontinuous nanoscale domains of semicrystalline PVDF, providing structural integrity, and poly(ethylene oxide) (PEO), providing selective transport channels of well-defined size and anti-fouling character. PVDF ultrafiltration membranes coated with PVDF-g-POEM exhibit fluxes higher than commercial thin film composite NF membranes and show excellent resistance to fouling by model biomolecule-containing solutions (proteins, polysaccharides and NOM) and oily microemulsions in high concentrations (1000-40,000 ppm). These membranes offer further prospects for fractionation/recovery of valuable constituents from wastewater through their molecular sieving capability.
3:00 PM - JJ2.2
New Materials for Water Purification.
Calvin Curtis 1 , Alex Miedaner 1 , Tanya Kaydanova 1 , David Ginley 1
1 , National Renewable Energy Laboratory, Golden, Colorado, United States
Show AbstractPure drinking water is necessary to sustain healthy human development, yet a considerable fraction of the world’s population drinks water of poor quality and suffers the associated health and developmental problems. Inexpensive solutions that are simple and generally applicable are highly sought after. Ultrafiltration and reverse osmosis treatments produce high-quality water, but they are slow and the associated membranes are expensive. Another approach to this problem is to use high-surface-area nanomaterials that actively absorb contaminants, but do not restrict flow like membranes do. We discuss here the development of tailored nanofiber materials and composites for this purpose. Boehmite ([AlO(OH)]n) nanofibers were synthesized by a hydrothermal process from Al(OH)3. These fibers are 2 nm wide by hundreds of nm in length and exhibit surface areas as high as 600 m2/g. They can readily be employed directly in a slurry, by forming a paper or by integration with support media such as cellulose or glass fibers. The hydroxyl groups and small size make these materials very active filter elements. Filters fabricated from these fibers remove bacteria and viruses from water very efficiently (>99.9999% removed) by irreversibly binding the pathogens. These filters were also used to remove a variety of metal ions and ion mixtures from water. We have also investigated other nanomaterials for these applications, including titania nanofibers and composites of boehmite and titania nanofibers with carbon, glass and cellulose fibers. These fibers represent a general class of high-aspect-ratio, nano-scale absorbent materials. The hydrothermal synthesis, characterization and application of these new materials in water filtration will be discussed.
3:15 PM - JJ2.3
Novel Bionanomaterials as Sensors for Detection and Quantification of Trace Contaminants in Water
Yi Lu 1 , Juewen Liu 1 , Geng Lu 1 , Daryl Wernette 1 , Hee-Kyung Kim 1 , Debapriya Mazumdar 1
1 Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
Show AbstractThere are a number of trace contaminants in water. Detection and selective removal of those contaminants is important to ensure the quality of our water resources. Designing sensors for trace contaminants is an effective way of achieving such a goal as it allows on-site, real-time detection at low concentration and with high spatial resolution. Despite recent progresses, designing sensors based on a single class of molecules for a broad range of analytes with high sensitivity and selectivity remains a significant challenge. We have been able to use a combinatorial method called in vitro selection to obtain DNAzymes (DNA with enzymatic activities, also called catalytic DNA) that can bind analyte of choice strongly and specifically (1). By labeling the resulting DNAzymes with fluorophore/quencher or gold nanoparticles, we have developed new generation of bionanomaterials that can serve as highly sensitive and selective fluorescent and colorimetric sensors for both metal ions (such as lead) and organic molecules (2-7) A fluorescent sensor for Pb2+ has a detection limit of 0.2 ppb, below the level of 15 ppb for drinking water. A novel approach of using an inactive variant of DNAzymes to tune the detection range of the sensors is also demonstrated (3). Recent progress will be presented.1. Jing Li et al. Nucleic Acids Res. 28, 481-488 (2000); 2. Jing Li and Yi Lu, J. Am. Chem. Soc. 122, 10466-10467 (2000); 3. Juewen Liu and Yi Lu, J. Am. Chem. Soc. 125, 6642-6643 (2003); 4. Juewen Liu and Yi Lu, Anal. Chem. 76, 1627-32 (2004); 5. Juewen Liu and Yi Lu, J. Am. Chem. Soc. 126, 12298-12305 (2004); 6. Juewen Liu and Yi Lu, J. Am. Chem. Soc. 127, 12677 - 12683 (2005); 7. Juewen Liu and Yi Lu, Angew. Chem., Int. Ed. (in press).
3:30 PM - JJ2.4
Wet Inversion Synthesis and Advanced Characterization of Nanofiltration Membranes
Jermey Matthews 1 , Hisham Mohamed 2 , Zenobia Lewis 1 , Donald Swarowski 2 , Kimberly Jones 1 , James Turner 2 3 , Michael Spencer 4 , Michele Caggana 2
1 Civil Engineering, Howard University , Washington, District of Columbia, United States, 2 , Wadsworth Center, Albany, New York, United States, 3 Department of Biomedical Sciences, The University at Albany, Albany, New York, United States, 4 Department of Electrical and Computer Engineering, Cornell University, Ithaca, New York, United States
Show AbstractWe have developed a technique for casting polymer membranes directly onto a silicon substrate through a wet inversion process. Novel cellulose acetate membranes have been synthesized through this process for lab-on-a-chip or microfluidic devices and have been shown to be hydrophilic negatively charged and exhibit good pure water permeability values. These cellulose acetate membranes have been shown from previous work to have molecular weight cut-off (MWCO) values as low as 350 Da – a typical cut-off for nanofiltration membranes. In the current characterization scheme, we measure pure water permeability, pressure-driven solute rejection, hydrophilicity by contact angle measurements, SEM imaging, surface roughness by AFM, mono- and divalent salt rejection, and the zeta potential-pH curve as a function of the composition of acetate. Results show that the membranes show specific water permeability values on the order of 10-8 m s-1 kPa-1, characteristic of nanofiltration membranes. The limiting rejection of uncharged organic solutes increased with increasing % acetate, and this value was used to calculate the effective pore radius. Initial results show that the effective pore radius for the membrane with the lowest acetate concentration was 2.45 nm and support the contention that the pore are on the nanometer scale. The water contact angle of the membranes was between 50-80 degrees. There does not seem to be any significant difference with regards surface roughness as a function of concentration. The zeta potential was essentially negative over the entire pH range and increased with increasing pH, with an isoelectric point near pH 3.5.
3:45 PM - JJ2.5
Switchable Magnetism for Arsenic Removal and Biomagnetic Separation.
Cafer Yavuz 1 , JT Mayo 1 , William Yu 1 , Joshua Falkner 1 , Sujin Yean 2 , Amy Kan 2 , Mason Tomson 2 , Vicki Colvin 1
1 Chemistry Dept., Rice University, Houston, Texas, United States, 2 Department of Civil and Environmental Engineering, Rice University, Houston, Texas, United States
Show AbstractUniform size and highly monodisperse (ó = 5-10%) magnetite (Fe3O4) nanocrystals were synthesized utilizing two different solvothermal reactions of iron (III) species (FeOOH and Fe(acac)3). Wide range of sizes (4, 6, 8, 11, 12, 14, 20, 26, 33 nm) achieved, characterized and used for further applications. Size dependent magnetic separation was studied and applied to polydisperse samples successfully. Magnetic field strength vs. percent retention of individual sizes reported. Magnetic multiplex separation method is created and proposed for bio-magnetic separations. Superparamagnetic limit for magnetite (Rc = 16 nm) is experimentally reported for the first time. Superparamagnetic property is used to turn on and off the magnetic activity of particles. Arsenic adsorption, 100% removal from wastewaters by nanosize magnetite is shown and compared to bulk material (100x better).
4:00 PM - JJ2: MatSyn
Break
4:15 PM - **JJ2.6
Bio-Inspired Self-Assembly of Synthetic Water Channels
C. Brinker 1 2 , Seema Singh 3 , Susan Rempe 4 , Kevin Leung 5 , Zhu Chen 2 , Ying-Bing Jiang 6 , George Xomeritakis 2
1 Self-Assembled Materials Dept., Sandia National Laboratories, Albuquerque, New Mexico, United States, 2 Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico, United States, 3 Ceramic Processing and Inorganic Materials, Sandia National Laboratories, Albuquerque, New Mexico, United States, 4 Computational Bioscience Dept, Sandia National Laboratories, Albuquerque, New Mexico, United States, 5 Surface & Interface Sciences, Sandia National Laboratories, Albuquerque, New Mexico, United States, 6 Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico, United States
Show AbstractOver billions of years, biological systems have evolved to solve difficult engineering problems like water collection and purification, self-cleaning and repair, environmental sensing, energy transduction, actuation, and adaptation. From a materials science perspective, nature’s solutions often involve disparate materials (hard/soft or hydrophilic/hydrophobic) combined in hierarchical architectures resulting in synergistic, optimized properties and combinations of properties. Emulating such proven natural designs in robust engineering materials using efficient, manufacturable processing approaches represents a fundamental current challenge. Using multicomponent self-assembly in combination with atomic layer deposition and chemical grafting we are attempting to translate the functional features of natural aquaporin channels into a synthetic silica-based membrane system. This talk will present new synthetic strategies for control of pore size, surface acidity and hydrophobicity in ultra-thin film (20-nm) membrane architectures. Transport of ions and water through the synthetic channels is characterized by so-called ‘patch clamp’ techniques (individual pores), scanning micro-electrode measurements, and conventional RO methods. Experimental results are interpreted on the basis of multi-scale modeling and simulation studies. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.
4:45 PM - JJ2.7
Characterization of Synthetic Zeolites Optimized for Heavy Metal Removal.
Gautam Kini 1 , Reda Mohamed 2 , Adel Ismail 2 , Ibrahim Ibrahim 2 , Ben Koopman 1
1 Department of Environmental Engineering Sciences, University of Florida, Gainesville 32611, Florida, United States, 2 Nanostructure Materials Laboratory, Advanced Materials Department, Central Metallurgical Research and Development Institute, Cairo - Helwan 11421 Egypt
Show Abstract5:00 PM - JJ2.8
2D Cationic Inorganic Materials: Anion-Exchangers For Water Purification.
Scott Oliver 1 , Daniel Brennan 1 , David Rogow 1 , Claudia Swanson 1
1 Department of Chemistry and Biochemistry, University of California, Santa Cruz, California, United States
Show Abstract5:15 PM - JJ2.9
Adsorption of Heavy Metals and Organic Contaminants on Functionalized Periodic Mesoporous Organosilicates
Conrad Ingram 1 2
1 , Calrk Atlanta University, Atlanta, Georgia, United States, 2 , WATER CAMPWS, Atlanta, Georgia, United States
Show AbstractConrad W. Ingram, Department of Chemistry, Clark Atlanta University, 223 James P. Brawley Drive,
[email protected], and Fengling Ding, Department of Chemistry, Clark Atlanta University, Clark Atlanta University, Fax: 404-880-6890,
[email protected] Cost effective and highly efficient adsorbents are in high demand in water purification processes for the removal of a wide range of chemical contaminants (including organic compounds and heavy metals). High surface area, stable, mesoporous organosilicates (MOS), with well defined pore structures (pore size > 1.5 nm) offer great potential in this area. This research is focused on (a) synthesizing MOS containing different types and concentrations of organic functionalities within (e.g.-CH2-), or grafted to (e.g. (-O)3SiC6H12NH2) the otherwise silicate pore walls, from the condensation of organosilicate precursors; and (b) the evaluation of the adsorption properties of the materials for removal of environmental contaminants. Thus, materials containing -Si–CH2-Si- pore walls and (-O)3SiC6H12X (X= SH, NH or imidazole) moieties extended within the pores were synthesized. The ethanol/acid extracted materials showed characteristic low angle X-Ray diffraction peaks reported for related mesostructures, had surface area of >1000 m2/g, pore volume of approximately 0.8 -1.0 cm3/g, and very sharp distribution of mesopores. The -SH and -NH functionalized materials showed high adsorption capacity for mercury and lead. The imidazole functionalized materials showed high adsorption capacity for dimethylphenol. The materials were inactive for the adsorption of trichloroethylene and toluene. These and details of adsorption kinetics, selectivity and mechanisms will be presented.
5:30 PM - JJ2.10
Antimicrobial Materials for Water Disinfection Based on Visible-light Active Photocatalysts.
Ping-gui Wu 1 , Rongcai Xie 1 , Zhongren Yue 1 , James Imlay 2 , James Economy 1 , Jian-Ku Shang 1
1 Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 2 Microbiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
Show AbstractAntimicrobial ceramic fibers based on photocatalysts were developed for water disinfection under visible light illumination. Nanocrystalline photocatalyst mesostructures were subsequently grown in the pore systems of mesoporous fiber templates. The photocatalysts were synthesized by doping titanium dioxide with various dopants. Optical absorption of the photocatalysts in the visible regime was found to depend strongly on the concentration of the dopant. Structures and properties of the mesoporous photocatalysts were examined by XRD, XPS, BET, AFM, SEM, HRTEM, UV-Vis and EPR. The antimicrobial effect of the mesoporous fibers were determined by biological testing on Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis endospores under controlled photocatalytic conditions. The antimicrobial activity of the photocatalysts was highly sensitive to dopant additions. The possible killing mechanism was determined by electron microscopy in combination with biological assays to be oxidative attacks.
5:45 PM - JJ2.11
Reverse Osmosis/Nanofiltration (RO/NF) Membrane Systems with Enhanced Water Permeability and Contaminant Rejection Capability.
Tasuma Suzuki 1 , Benito Marinas 1 , Yunyi Lu 2 , Jeffrey Moore 2
1 Environmental engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 2 chemistry, materials science & engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
Show AbstractThe overall objective of this project is the development and characterization of new NF membrane materials with enhanced water permeability and rejection of water contaminants ranging from small molecules to large macromolecules. The initial goal was to prepare a first generation of synthetic NF membranes with narrow pore size distributions and easily modifiable chemical functionalities compared to commercially available products such polyamide (PA) membranes. The base materials used for the active layer were triethyleneglycol monomethyl ether (Tg) macrocyclic building blocks. Modular Tg macrocyclic building blocks were synthesized by a one-step large-scale precipitation-driven cyclization approach. NF membranes were then prepared by depositing an active layer of Tg macrocycles onto two polyethersulfone ultrafiltration (UF) membranes serving as support layers. The nominal molecular weight cutoffs specified for the two ultrafiltration membranes are 900-2,300 and 4,000-9,000 Dalton. Permeation experiments were performed with these Tg NF membranes in a flat-leaf cell. Experimental variables were the mass of Tg on the active layer of the membrane, hydraulic pressure, and operating time. Rhodamine-WT (R-WT), with a molecular weight of 521 Da, was used as a surrogate solute for water contaminants. The optimum Tg membranes were found to have a water permeability three- to four-fold (0.3-0.4 m/(d atm)) higher than those specified for commercially available NF membranes (0.1 m/(d atm)). However, the percent rejection of R-WT provided by the optimum Tg membranes (70-80 percent) was lower than that provided by the commercially available NF membranes (95-99 percent). A possible explanation currently under investigation is that a small percentage of the water flux (~20-30 percent) was passing through pores of the ultrafiltration membranes that because of their relatively large size were not fully covered with the Tg film during the preparation of the active layer.Additional experiments were performed with membranes to which the relatively large pores were plugged with polystyrene microspheres of various sizes (mean diameters of 13, 16, and 20 nm) prior to depositing the active layer of Tg macrocycles. Experimental results revealed that at the optimum conditions, the percent rejection of R-WT (93-96 percent) was comparable to that obtained with commercial NF membranes while the water permeability obtained with these new plugged Tg membranes (0.2-0.3 m/(d atm)) was two- to three-fold that of the commercial NF membranes.
JJ3: Poster Session: Materials for Water Treatment
Session Chairs
David Ginley
Mark Shannon
Wednesday AM, April 19, 2006
Salons 8-15 (Marriott)
9:00 PM - JJ3.1
A Novel Method for Producing a Porous Anodized TiO2 Membrane for Water Desalination and Purification Applications.
Ryan McGrath 1 , M Misra 1
1 Material Science, University of Nevada, Reno, Nevada, United States
Show Abstract9:00 PM - JJ3.2
Characterizations of Low-cost Porous Anodic Alumina for Drinking Water Treatment.
Daniel Lo 1 , R Budiman 1 , Millie Adam 2 , Tommy Ngai 2
1 Mechanical and Manufacturing Engineering, University of Calgary, Calgary, Alberta, Canada, 2 , Centre for Affordable Water and Sanitation Technology, Calgary, Alberta, Canada
Show Abstract9:00 PM - JJ3.3
Adsorption Kinetics of Defluoridation by Modified Ion Exchange Resin
Balakrushna Padhi 1 , Arun Sharma 1 , Sanjaya Pattanaik 1
1 R&D, National Aluminium Company Limited, Damanjodi, Orissa, India
Show Abstract9:00 PM - JJ3.4
Removal of Metals from Water with Boehmite-Based Filters.
Calvin Curtis 1 , Alex Miedaner 1 , Samuel Wilson 1 , David Ginley 1
1 , National Renewable Energy Laboratory, Golden, Colorado, United States
Show Abstract9:00 PM - JJ3.5
A New Strategy for Water Purification: Cationic Inorganic Materials.
David Rogow 1 , Claudia Swanson 1 , Scott Oliver 1
1 chemistry, UCSC, Santa Cruz, California, United States
Show AbstractAnions in wastewater are typically trapped by organic resins, which are of very low thermal and chemical stability. Anionic contaminants in waterways include a wide variety of anionic pollutants, including nitrates, perchlorates and pharmaceuticals. Next-generation approaches to water purification will include new stable porous inorganic materials capable of removing a wide range of contaminants and adhering to emerging standards of purity. To date, only one such cationic extended inorganic material is known: the layered double hydroxides (LDH’s). We are interested in the solvothermal synthesis of new cationic structures, using anions to direct the formation of a positively charged host structure. Anions used in this way are referred to as structure directing agents (SDA’s) and are essentially exchangeable guests in the final material. We have synthesized new layered cationic inorganic structures consisting of a positively charged framework with anions residing in the interlamellar spaces. These materials have potential application in a number of anion-based applications, including ion exchange and base catalysis. The materials are stable at relatively high temperatures and exhibit promising transport properties. Due to the variety of coordination numbers and possible ligands, Pb and Gd systems have yielded particularly interesting cationic structures. These materials are synthesized using water as the solvent. The structures remain stable up to approximately 375oC as determined by TGA. Details regarding the synthesis and characterization of these materials, and their physicochemical properties will be discussed. In addition, we will present the results of anion exchange experiments for a variety of organic and inorganic anions.
9:00 PM - JJ3.6
Synthesis and Characterization of Anion Sorbents for Water Purification.
Claudia Swanson 1 , David Rogow 1 , Scott Oliver 1
1 Chemistry & Biochemistry, University of California, Santa Cruz, California, United States
Show AbstractWe are focusing on the synthesis of new inorganic materials with technologically useful properties in areas such as wastewater treatment. Specifically, our strategy is to isolate porous cationic structures for the absorption of anionic contaminants in wastewater, e.g. inorganic oxometallates or organic pharmaceuticals. We focus on solvothermal synthetic techniques, namely metal precursors in aqueous, glycol, pyridine or mixed solvent systems. To our knowledge, there are only two cationic porous materials known to date that are purely inorganic: layered double hydroxides (LDHs) and our previously reported BING-5. In recent work, a new related structure having antimony as metal source has been discovered. We have characterized the material by various methods, including X-ray diffraction (XRD, powder and single crystal), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). The synthetic strategy and characterization and anion-exchange data will be presented.
9:00 PM - JJ3.7
Protein Crystals Used for the Removal of Heavy Metals from Waste Water.
Achala Talati 1 , Joshua Falkner 1 , Sujin Yean 2 , Junyan Zhang 1 , Heather Shipley 2 , Amy Kan 2 , Mason Tomson 2 , Vicki Colvin 1
1 Chemistry, Rice University, Houston, Texas, United States, 2 Civil and Environmental Engineering, Rice University, Houston, Texas, United States
Show Abstract
Symposium Organizers
Mark A. Shannon University of Illinois, Urbana-Champaign
David Ginley National Renewable Energy Laboratory
Alan M. Weiss Global Water Group
JJ4: Interaction Characterization Methods
Session Chairs
Wednesday AM, April 19, 2006
Room 2022 (Moscone West)
9:30 AM - **JJ4.1
Thermodiffusion of Nanoparticles in Water.
David Cahill 1 , Shawn Putnam 1
1 Materials Science and Engineering, CAMPWS, University of Illinois, Urbana, Illinois, United States
Show AbstractCross-terms in the transport coefficients are often exquisitely sensitive to details of the thermodynamics and kinetics of a system. In our case, we consider mass transport induced by a temperature gradient, commonly referred to as thermodiffusion or the Soret effect, with the goal of gaining new insight on the nature of interfaces with water. Many theories have been proposed to describe thermodiffusion of solid particles; we give special attention to Derjaguin’s description based on the excess enthalpy of the liquid near the particle surface. Suspensions of 30 nm diameter, carboxyl functionalized, polystyrene latex spheres have been the subject of our initial studies. We measure particle transport in dense suspensions using a micron-scale optical beam deflection method: an oscillating temperature gradient, 2 mHz < f < 2 kHz, is established by two thin-film metal heater strips, 7 microns wide and separated by 25 microns. We extract the thermodiffusion coefficient by modeling the magnitude and phase of the laser beam deflections created by gradients in the particle concentration. In strong electrolytes, thermodiffusion of nanoparticles is controlled by differences in the thermodiffusion of the cations and anions. In weak electrolytes, the thermodiffusion coefficient of polystyrene latex is negative and approximately independent of particle concentration and ionic strength. Derjaguin’s model predicts a positive thermodiffusion coefficient if the excess enthalpy is dominated by polarization of water molecules in the electric-field of the double-layer.
10:00 AM - JJ4.2
Measurement of Interfacial Water Properties within Nanometers of Polymer Surfaces Using the Interfacial Force Microscope.
Dale Huber 2 , J. E. Houston 1 , Ben Frankamp 2 , Bruce Bunker 1
2 Nanostructure and Semiconductor Physics Department, Sandia National Labs, Albuquerque, New Mexico, United States, 1 Biomolecular Materials and Interfaces, Sandia National Labs, Albuquerque, New Mexico, United States
Show Abstract10:15 AM - JJ4.3
The Nature of Water and Transport in Functionalized Poly(phenylene)s.
Michael Hickner 1 , Christopher Cornelius 1 , Michael Hibbs 1 , Cy Fujimoto 1 , Todd Alam 2
1 Chemical & Biological Systems, Sandia National Laboratories, Albuquerque, New Mexico, United States, 2 Electronic Materials and Nanostructured Materials, Sandia National Laboratories, Albuquerque, New Mexico, United States
Show Abstract10:30 AM - JJ4.4
High-Temperature Hydroxylation of Alumina Crystalline Surfaces: An FTIR-ATR and SFG Spectroscopic Study
Ramesh Chandrasekharan 2 , Victor Ostroverkhov 1 , Shaurya Prakash 2 , Luning Zhang 1 , Glenn Waychunas 3 , Yuen-Ron Shen 1 , Mark Shannon 2
2 Department of Mechanical and Industrial Engineering, University of Illinois, Urbana-Champaign, Urbana, Illinois, United States, 1 Department of Physics, University of California, Berkeley, Berkeley, California, United States, 3 Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States
Show AbstractUnderstanding the structure of alumina surfaces and their interaction with water is important for modern technology and environmental science. In particular, alumina has been extensively studied in the context of its catalytic properties, and used as a robust support material for other catalysts, as well as a material for filtration membrane applications and in microfluidic systems. Different crystalline alumina surfaces prepared under different conditions can have very different hydrophilicity or hydrophobicity because of the presence of surface hydroxyls, but their structures at the molecular level are not yet understood. We used sum-frequency vibrational spectroscopy as well as attenuated total reflection (ATR) IR spectroscopy in the OH stretch range to probe hydroxyls and possible adsorbed water molecules on α-Al2O3 cut along (0001), (1120), and (1-102) crystallographic planes that were annealed at 1550 and 1000°C in gas mixtures of different compositions. SFVS is known to be surface-specific, while ATR-IR spectroscopy is sensitive to an interfacial layer of about 100 nm thick. If hydroxyl groups appeared only in a monolayer at the interface, then the spectra from SFVS and ATR-IR must be correlated under the limit that they obey different selection rules. We found in our experiment that the spectra of different alumina surfaces were indeed different, suggesting that the corresponding surface structures were different. High-temperature annealing of surfaces appeared to have enhanced the surface hydrophobicity.This work was supported by the NSF Science and Technology Center of Advanced Materials for Purification of Water with Systems (Water CAMPWS; CTS-0120978).Corresponding Authors: Y. R. Shen:
[email protected] M. A. Shannon:
[email protected]10:45 AM - JJ4.5
Magnetic Resonance Imaging (MRI) of Water Diffusion in 2-Hydroxyethyl Methacrylate (HEMA) Gels
Shaurya Prakash 2 , Guy Raguin 2 , Cibele Falkenberg 2 , Glennys Mensing 2 , John Gerogiadis 2 , Mark Shannon 2
2 Mechanical and Industrial Engineering, University of Illinois, Urbana, Illinois, United States
Show AbstractIt is well known that the specific hydrogel synthesis procedure such as polymerization methodology, curing temperature, and cross-linker content affect gel microstructure, and can even create spatial inhomogeneities within the gel. The objective of this study is to establish a relationship between the local gel pore structure and the local water diffusion coefficient. Diffusion-limited water transport is used to probe and characterize the pore space. A fundamental study focusing on correlating the local water diffusion coefficient to the local free water content in 2-hydroxyethyl methacrylate (HEMA) gels was conducted. HEMA gels were synthesized with different nominal water content (50% to 90%). Scanning electron microscopy (SEM) imaging of the gels shows different pore structures and porosity in the gels. Increasing nominal water content increases porosity but appears to reduce pore size of the gels. For instance, the pore diameter decreases from ca. 15 to 20 μm average for a 65% water content sample to less than ca. 5 μm pores for the 90% water content gels. The qualitative SEM data are supplemented with MRI measurements of local diffusion coefficient distribution and local water content profiles. The MRI experiments are conducted on a 600 MHz scanner with gradient capabilities up to 100 G/cm and a rise time of 0.1 ms. The local water content is measured via two spin-echo images with sufficiently long repetition time (TR) to eliminate T1-weighting and two values for the echo time (TE) in order to account for T2-weighting. The local diffusion coefficient is determined using a standard pulsed-field gradient spin-echo sequence. The SEM data suggest that much of the free water occupies an interconnected larger (micron sized) pore space, since these pores seem to occupy a significant fraction of the free volume. The local water content and diffusion coefficient data obtained via MRI are correlated in terms of several single-parameter diffusion models for the hydrogel (Makie-Meares, Stokes-Einstein, Brownian motion around overlapping spheres).This work was supported by the NSF Science and Technology Center of Advanced Materials for Purification of Water with Systems (WaterCAMPWS; CTS-0120978).
11:30 AM - **JJ4.6
Drag on a Scanning Probe near a Hydrophilic Surface.
Peter Feibelman 1
1 Surface and Interface Sciences, Sandia National Laboratories, Albuquerque, NM, New Mexico, United States
Show Abstract12:00 PM - JJ4.7
A Method to Measure surface stress on Solid-Liquid Interfaces
Xijing Zhang 1 , David Cahill 1
1 Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
Show AbstractThe microscopic properties of solid-liquid interfaces can be probed by surface stress, a macroscopic physical quantity. We describe an optical system that directly measures the bending curvature of a micro-cantilever; the surface stress on the solid-liquid interface is then proportional to the curvature. The long term stability of our approach is excellent because it avoids the measurement of bending angle or displacement of the light beam. As examples, we report the change in interface stress for different silica surfaces in methanol/2-propanol mixtures. Those silica surfaces include silica grown by ozone oxidation of silicon, grown by thermal oxidation of silicon and different polymer functionalized silica. The experiment provides quantitative information for understanding the adsoptions and reactions of methanol and 2-propanol on functionalized silica surfaces.
12:15 PM - JJ4.8
Characterization of Arsenic (III) Partitioning at the NF/RO Membrane Active Layer-Aqueous Interface by Rutherford Backscattering Spectrometry.
Baoxia Mi 1 , Benito Marinas 1 , Fumiya Watanabe 2 , David Cahill 2
1 Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 2 Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
Show AbstractArsenic (III), a relatively common water contaminant of current concern in the United States, is poorly rejected by most commercially available reverse osmosis (RO)/nanofiltration (NF) membranes. Arsenious acid (H3AsO3) with a dissociation constant pKa of 9.2 is the predominant form of As(III) at the typical natural water pH range of 6-9. Elucidating the mechanisms responsible for the transport of neutral H3AsO3 molecule through state-of-the-art RO/NF membranes is an important step toward the development of a new generation of membrane materials capable of providing effective As(III) removal.Permeation experiments have revealed that the transport of As(III) through RO/NF membranes is mainly by diffusive permeation which comprises three steps: sorption into, subsequent diffusion through, and desorption from the membrane active layer. Therefore, the partition coefficient of As(III) at the aqueous phase/membrane active layer interface, could play a critical important role in its transport through RO/NF membranes.Most commercial composite RO/NF membranes have a very thin active layer as the main discriminating layer to remove contaminants. The extreme thinness of this layer, on the other hand, constitutes an obstacle to precisely characterizing the layer structure and its functioning. Rutherford backscattering spectrometry (RBS), however, has the capability of determining elemental concentration profiles within a thin film. RBS was used in this study to characterize the elemental composition and membrane active layer thickness, as well as the partitioning of As(III) from aqueous phase into membrane active layer.Several commercial RO/NF membranes made with different materials, such as polyamide, polyvinyl alcohol (PVA), and sulfonated polyethersulfone (SPES), were selected for this study. RBS successfully differentiated the active layer from the support layer, and determined the elemental composition and thickness of the active layer. It was found that the partitioning of As(III) at aqueous phase/membrane interface is different for different membrane materials. Polyamide membranes have higher As(III) partitioning than PVA or SPES membranes. Furthermore, among the polyamide membranes tested, those for which ATR-FTIR analyses revealed the presence of higher concentrations of amide functional groups had the highest arsenic partition coefficients. Comparing As(III) partition coefficients with those of potassium and iodide ions, used as background electrolytes, showed that positively charged K+ consistently had higher partition coefficients than the neutral molecule H3AsO3, while negatively charged I- have the lowest partitioning of all three species, consistent with these RO/NF membranes being slightly negatively charged.
12:30 PM - JJ4.9
Biocolloidal Cryptosporidium Parvum Oocysts and Giardia Lamblia Cysts: Exploration of Nano-Scale Surface Interactions Relevant to Drinking Water Treatment.
Robert Considine 1 , Anne-Mari Ruohola 1 , David Dixon 2 , Calum Drummond 1
1 Molecular and Health Technologies, CSIRO, Clayton, Victoria, Australia, 2 ARC Particulate Fluids Processing Centre, Department of Chemical and Biomolecular Engineering, The University of Melbourne, Parkville, Victoria, Australia
Show AbstractCurrently, one of the main barriers to Cryptosporidium parvum oocyst and Giardia lamblia Cyst contamination of drinking waters is provided by sand-bed filtration. In this study an atomic force microscope (AFM) has been used to measure the force of interaction between oocysts of C. parvum and cysts of G. lamblia and a model sand surface (silicate glass). The AFM force curves have been compared and contrasted with the corresponding electrical potentials obtained from electrophoretic measurements (ζ). It has been found that the surfaces of the oocysts and cysts possess a hairy layer, most likely a result of surface proteins extending into solution. The hairy layer imposes a steric repulsion between the oocyst/cyst and sand surface, in addition to any electrostatic repulsion. For the C. parvum oocysts the hairy layer collapsed to varying extents in the presence of dissolved calcium and dissolved organic carbon, indicating that the oocysts may be more readily adsorbed onto the model sand surface under these conditions. Conversely, as the two surfaces are pulled apart, the occasional attachment of oocyst and cyst surface proteins to the model sand surface can result in adhesion. The AFM results offer new insights into the surfaces of C. parvum oocysts and G. lamblia cysts, and the mechanism of interaction with model sand surfaces under conditions relevant to sand-bed filtration.
JJ5: Constituent Interactions with Materials
Session Chairs
Wednesday PM, April 19, 2006
Room 2022 (Moscone West)
2:30 PM - **JJ5.1
Structure and Growth of Water Films and Interfaces.
M. Salmeron 1
1 Materials Sciences Division, Mail Stop 66-208, Lawrence Berkeley National Lab, Berkeley , California, United States
Show AbstractTwo experimental techniques have been utilized to study the structure and growth of water monolayers and multilayers on a variety of substrates, including metals (Pd, Ru, Cu), oxides (TiO2, SiO2, mica) and thick water structures (films and droplets). These techniques are Scanning Probes (AFM and STM) and Photoelectron techniques (XPS and NEXAFS). On metals and oxides we could determine the molecular level structure of the first few layers in contact with the substrate. In general the substrate has a strong influence in determining the structure of the water films, including molecular orientation and dissociaton into OH and H. The results open a new perspective in our understanding in the problems of wetting, hydrophyllicity and hydrophobicity. I will review these results and point to future directions.
3:00 PM - JJ5.2
Competitive Molecular Adsorption at Liquid/Solid Interfaces Probed by Sum Frequency Vibrational Spectroscopy.
Luning Zhang 1 , Weitao Liu 1 , Y. Ron Shen 1
1 Physics, University of California, Berkeley, Berkeley, California, United States
Show Abstract3:15 PM - JJ5.3
Molecular Ordering, Structure, and Dynamics of Water at Mineral Surfaces: MD Computer Simulation.
Andrey Kalinichev 1 2 , Jianwei Wang 3 , R Kirkpatrick 1 2
1 Department of Geology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 2 NSF Water CAMPWS, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 3 Department of Geology, University of California at Davis, Davis, California, United States
Show Abstract3:30 PM - JJ5.4
Computational Investigation Into the Adsorption of Pollutants onto Mineral Surfaces: Arsenate and Dolomite
Kat Austen 1 2 , Ben Slater 1 2 , Kate Wright 3 , Julian Gale 3
1 The Royal Insitution of Great Britain, Davy Faraday Research Laboratory, London, London, United Kingdom, 2 Department of Chemistry, University College London, London United Kingdom, 3 Nanochemistry Research Institute, Curtin University of Technology, Perth, Western Australia, Australia
Show AbstractArsenic and its compounds are an important area of study because of their impact on human health and the environment[1,2]. Pollution from human activity has elevated environmental arsenic levels, increasing their concentrations in areas around industrial plants and mines[1,3]. Consequently, new information on arsenic chemistry and its interaction with species with which it comes into contact is vital in reducing arsenic contamination in water supplies. In most groundwaters it is expected that arsenate will be the species most strongly sorbed onto mineral surfaces[1,4]. A prevalent naturally occurring carbonate mineral, dolomite (CaMg(CO3)2) is often found in areas with high aqueous arsenic concentrations[1]. Despite this, the interaction between arsenate and carbonate minerals has received little attention. This study investigates the aqueous adsorption of the singly deprotonated arsenate molecule, [AsO2(OH)2]-, onto dolomite’s most morphologically important surface using periodic Quantum Mechanical Molecular Dynamics. The structures of the adsorbate and the adsorbent under pH neutral, solvated conditions were studied initially, with particular attention paid to the possibility of water dissociation on the mineral surface. Subsequently, the free energy of adsorption was calculated, and the most favourable complexation geometry was ascertained for the system. This work provides not only insights into the interaction of two important components of the environment using state-of-the-art computational techniques, but also reports the progress of the application of computational methods to mineralogical and environmental problems.1P. L. Smedley and D. G. Kinniburgh, Applied Geochemistry 17 (5), 517 (2002).2A. H. Smith, E. O. Lingas, and M. Rahman, Bulletin Of The World Health Organization 78 (9), 1093 (2000).3D. Sanchez-Rodas, J. L. Gomez-Ariza, I. Giraldez et al., Science Of The Total Environment 345 (1-3), 207 (2005); J. Mahoney, D. Langmuir, N. Gosselin et al., Applied Geochemistry 20 (5), 947 (2005).4A. G. Gault, D. A. Polya, J. M. Charnock et al., Mineralogical Magazine 67 (6), 1183 (2003).
3:45 PM - JJ5.5
Removal of Heavy Metals from Drinking Water by Adsorption on Nanostructured Iron Oxide Membranes.
Maria Fidalgo de Cortalezzi 1 , Laura Calvo 1 , Nicolas Gonzalez Eiras 1 , Pablo Segura 1 , Sergio Bocchi 1 , Emiliano Casagrande 1 , Lucia Olmedo 1 , Natalia Chalup 1
1 Department of Chemical Engineering, Instituto Tecnologico de Buenos Aires, Buenos Aires Argentina
Show AbstractClean water constitutes a valuable and scarce resource, as a raw material in manufacture processes or as a source of drinking water. There is a need for research on new technologies for water treatment applied to industrial wastes with specific characteristics or due to more stringent standards on drinking water. The objective of this work was to evaluate the use of iron oxide ceramic membranes for the removal heavy metals and organics from drinking water, and to quantify the effect of the presence of natural organic matter on the removal efficiency of heavy metals by the proposed membranes. The presence of organic matter in the water often gives rise to undesirable taste and smell. In addition, organic matter is the precursor to highly toxic compounds formed during the chlorination of drinking water. Contamination of water sources with arsenic is an important issue in many parts of the world, as is the case in Argentina. Traditional water treatment schemes do not address the removal of heavy metals present in trace levels, and usually are ineffective to protect human health. We investigated the removal of heavy metals (lead, arsenic, chromium) and organic matter from water by adsorption and filtration. Ultrafiltration membranes are highly effective in the removal of microorganisms and organic macromolecules. Lead, arsenic, and chromium are important contaminants due to their high toxicity; given their affinity towards the iron oxides, it is possible to remove them by adsorption processes. Numerous researchers have shown the ability of the iron oxides to adsorb heavy metals, phosphates and organic matter. This can also be a problem during filtration, as adsorption of organics on the pore walls of the membranes can lead to fouling and clogging. We fabricated supported ultrafiltration iron oxide ceramic membranes from iron oxide nanoparticles. The starting material is lepidocrocite (γ-FeOOH) and after formation of the membrane and sintering it transforms into hematite (α-Fe2O3). The resulting ceramic has an average pore size of 20 nm and a BET surface area of 90-100 m2/g. The process being investigated is targeted to heavy metal removal at the point of use (e.g. consumer tap for drinking water). The advantage over existing methods that use powdered iron oxides as an adsorbent is that the latter needs a separation step to obtain drinking water free from adsorbent media. Some researchers have proposed iron oxide coated sand or activated carbon columns with good results. Our method, however, yields a more compact system and thus economically more convenient, both in terms of materials and energy costs.
4:30 PM - **JJ5.6
Interactions Between Water and Model Membrane Surfaces.
Bruce Bunker 1 , Dale Huber 1 , Erik Watkins 2 , Ben Frankamp 1 , Greg Holland 1 , Todd Alam 1 , Gayle Thayer 1 , Darcy Farrow 1
1 Biomolecular Materials and Systems, Sandia National Laboratories, Albuquerque, New Mexico, United States, 2 , Los Alamos National Laboratory, Los Alamos, New Mexico, United States
Show AbstractThe ordering of water is critical to the performance characteristics of reverse osmosis membranes, influencing key parameters such as water permeability and salt exclusion. Unfortunately, most commercial membranes are complex structures with surfaces and internal structures that are difficult to explore using standard analytical methods. In order to gain mechanical insights into how water interacts with membrane materials, we have prepared a series of self-assembled monolayers terminated with short segments of model polymers in geometries tailored for specific analytical techniques. Information regarding the molecular structure and dynamics of water and the polymers has been obtained using a combination of solid-state NMR and sum frequency generation IR results. Ordering of water and salt exclusion/concentration near the interface has been studied via neutron reflectivity, while the physical properties of the water have been obtained using the interfacial force microscope (IFM). This talk will highlight results that have been obtained on model nylon 66 surfaces. Both NMR and neutron scattering results show that the native nylon monolayers are highly crystalline. Both techniques indicate that even small amounts of water (10%) are sufficient to induce a crystalline-to-amorphous phase transition within the nylon surface, with water being incorporated within the amorphous phase. NMR results show that the presence of water enhances the chain dynamics of the polymer, influencing water diffusion rates. Neutron scattering results indicate that a 4.5 nm-thick layer of interfacial water having a density that is 95% that of bulk water forms above the nylon surface, mirroring the ordered water seen adjacent to antifouling surfaces such as polyethylene oxide. When salts such as MgCl2, LiCl, and KF are added to solution, strong gradients in salt concentrations are detected in addition to the ordered water. In some instances, the ordering of the water generates high viscosity interfacial zones that are apparent in IFM measurements. Implications of the results to parameters of interest to reverse osmosis membranes, including diffusion, water viscosity, salt exclusion, and scale formation, and biofouling are discussed.
5:00 PM - JJ5.7
Interfaces of methanol:water Mixtures with an OTS-coated Substrate Probed by Sum-frequency Vibrational Spectroscopy.
Weitao Liu 1 , Luning Zhang 1 , Y. R. Shen 1
1 Physics, University of California at Berkeley, Berkeley, California, United States
Show AbstractAqueous solutions of short chain aliphatic alcohols are important reagents in organic chemistry, and their physical, chemical properties at hydrophobic interfaces play key roles in many applications such as water purification. Taking methanol-water mixtures with an OTS(octyltrichlorosilane) self-assembling monolayer covered silica as model hydrophobic interfaces, we used surface-specific sum-frequency vibrational spectroscopy (SFVS) to probe their interfacial structures at the molecular level. From the vibrational spectra in the C-H stretching regime, we deduced the interfacial coverage and orientation of methanol molecules vs. its molar concentration. The results showed that methanol forms a polar-ordered interfacial monolayer with the same average orientation at all concentrations. The hydrogen bonding property of methanol with neighboring molecules was manifested in the frequency shift of its CH3 symmetric stretching mode. We also probed the OH stretching vibrations of methanol and water. By analyzing the dangling-OH mode, we monitored the correlation between the surface number density of methanol molecules and water free OH bonds. Ab initio calculations were used to help investigate the interfacial structures. This work was supported by the NSF Science and Technology Center of Advanced Materials for Purification of Water with Systems (Water CAMPWS; CTS-0120978).
5:15 PM - JJ5.8
The Correlation of Structure with Activity of Bimetallic PdxCu1-x Nanocatalysts Developed for Nitrate Reduction of Drinking Water.
Huiping Xu 1 2 , Kathryn Guy 3 4 , Zhenyu Liu 1 , Brian Chaplin 5 4 , Richard Lee 2 , Charles Werth 5 4 , John Shapely 3 4 , Judith Yang 1
1 Materials Science & Engineering, The University of Pittsburgh, Pittsburgh, Pennsylvania, United States, 2 , R. J. Lee Group, Inc, Monroeville, Pennsylvania, United States, 3 Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 4 , NSF-sponsored Center Advanced Materials for Purification of Water with Systems (Water CAMPWS), Urbana, Illinois, United States, 5 Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
Show AbstractReductive removal by hydrogeneration using supported Pd/M bimetallic metallic catalysts has emerged as a promising alternative for the removal of many water contaminants including nitrate [1]. In order to better understand how the atomic arrangement of Pd and a second element, such as Cu, affect the activity of nitrate reduction and selectivity of dinitrogen, we report a systematic study of novel PVP stabilized nanoscale Pd/Cu colloids with metal ratios ranging from 50:50 to 90:10 (Pd: Cu) by electron microscopy, including Z-contrast imaging [2], energy dispersive X-ray emission (EDX) and electron energy-loss spectroscopy (EELS) techniques [3] , electron diffraction and high-resolution electron microscopy (HREM). We found the strong correlation between the colloid particle core-shell structures with high activity for the nitrate reduction. As the increase of the amount of copper from 10at. %Cu for the 90:10 colloids to 40at.%Cu for the 60:40 colloids, the nitrate reduction rate increases from zero to near 0.007(1/min.); particle size slightly decreases from near 5.2nm to near 3.3nm; and the internal structure of individual colloid nanoparticles changes from homogeneous fcc structure for the colloids with the amount of copper ≤ 20at. % to inhomogeous core-shell structure for the colloids with the amount of copper ≥ 30at. %. In addition to this, we plan to perform the same procedure on post-catalysis PdxCu1-x colloid nanoparticles and provide deep insights into this unusual structure-activity correlation. [1]. A. Kapoor and T. Viraraghavan, J. of Environmental Engineering, 123, 371 (1997). [2]. A. Singhal, J.C. Yang and J.M. Gibson, Ultramicroscopy, 67, 191 (1997). [3]. K. Sun, J. liu et al, J. Phys. Chem. B 106, 12239 (2002). The authors at the University of Pittsburgh are supported by the University of Pittsburgh, School of Engineering Heinz and Bevier endowments and the authors at University of Illinois at Urbana-Champaign are supported by NSF.
5:30 PM - JJ5.9
Role of Activated Carbon Pore Size Distribution in the Competitive Adsorption between Trace Contaminant and Natural Organic Matter
Li Ding 1 , Vernon Snoeyink 1 , Benito Marinas 1 , Zhongren Yue 2 , James Economy 2
1 Civil & Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 2 Material Science & Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
Show AbstractThe goals of this research are to study how pore size distribution (PSD) of activated carbon (AC) affects the extent of competitive adsorption between natural organic matter (NOM) and trace organic contaminants, and to use this information to develop new carbons that minimize competition from NOM. There are two competitive adsorption mechanisms between NOM and trace contaminants. Molecules adsorb preferentially in pores with comparable diameters to their sizes. Therefore, small NOM molecules with similar size to that of trace contaminants compete directly for available sites within AC pores. Larger NOM molecules, unable to access the adsorption sites targeted by the trace contaminant due to size exclusion effects, adsorb in larger pores and reduce the diffusion rate of trace contaminants into the micropores by pore constriction. The PSD thus affects the adsorption of NOM and how NOM competes with the target trace contaminant. The quantity of micropores (<20Å), especially primary micropores (<8Å), where direct competition effects primarily occur, affects the extent of direct competition, while the volume of mesopores with diameters in the 20~50Å range affects the extent of pore blockage. .Carbon activation conditions were varied and precisely controlled and a new AC named “Pellet II” was developed with a mesopore volume higher than most commercial carbons but with a total BET surface area similar to commercial carbons.Single solute adsorption of atrazine, simultaneous adsorption of atrazine and NOM in a natural water, and adsorption of atrazine on AC preloaded with NOM were conducted with Pellet II and two commercial ACs, Norit A and Norit B. PSD analysis by nitrogen gas adsorption showed Norit A and Pellet II have similar volumes of micropores but Pellet II has more mesopores, while Norit B has the smallest volumes in both micropores and mesopores. The adsorption capacities obtained from single solute isotherms of atrazine on these three carbons correlated with the micropore volume of the carbons. The capacity of AC for NOM correlated well with the mesopore volume.Kinetic experiments were performed with carbons preloaded with NOM. Comparison of Norit A and Pellet II data revealed that the same level of NOM loading on Pellet II, in mass NOM per mass AC, had smaller pore blockage effects on atrazine compared to those observed with Norit A. This observation confirmed that mesopores helped to alleviate the pore blockage effects of NOM. Experiments with the third carbon, Norit B, are under way.We also modified an adsorption model called “COMPSORB”, which describes both direct competition and pore blockage effects in flow-through adsorption/filtration systems, so that it can be applied to predict these effects. After batch isotherm and kinetics tests are completed, data will be incorporated into the model to verify system performance and to further compare the three carbons with respect to their application in water treatment processes.