Surface Enhancement of Coir Fibers for Better Bacterial Accumulation

Nowadays, contamination of water via pathogenic bacteria, viruses, and parasites is one of the major health problems facing by the society. Therefore, an effective method is essential to rapidly capture the bacteria from water to minimize water contamination by pathogens. The usage of chemical disinfectants in conventional water purification processes has become a challenge due to the formation of carcinogenic by-products and antibiotic-resistant bacterial pathogens. As a solution to that, this study introduces an eco-friendly bacteria capturing strategy using natural coconut fibers as a substrate, which is modified by a novel polymeric coating. This polymer coating consists of an amine functionalized diatomaceous earth/poly(vinyl acetate) composite. Diatomaceous earth (DE) is an inexpensive, environmentally benign, highly porous amorphous silica structure and DE has been treated with a (3-Aminopropyl)triethoxysilane coupling agent to enhance bio-affinity toward bacteria. A poly(vinyl acetate) (PVAc) binder is used to disperse treated DE. PVAc is a nontoxic, eco-friendly thermoplastic adhesive used as a binder to prepare coatings. Alkaline treated coconut fibers were dipped in the treated DE/PVAc composite coating to prepare the modified fibers. The positive charges of the surface amine functionality of the treated DE can promote strong electrostatic interaction with the negatively charged bacterial cell membrane. Further, the pendent propyl group of amine functionality can also play a supplementary role in attracting bacterial pathogens by forming hydrophobic interactions. Fourier transform infrared (FTIR) spectroscopic analysis was conducted to confirm the presence of silane coupling agents on the DE and to characterize the chemical components of (3-Aminopropyl)triethoxysilane treated DE/PVAc coated coconut fiber and raw coconut fiber. The bio-affinity of raw coconut fiber and modified coconut fiber was compared in terms of bacteria capturing ability. Bacterial capturing ability was investigated based on UV spectrophotometer absorbance measurements using <i>E. coli</i> bacteria as a model bacteria type. The UV absorbance measurements of the <i>E.coli</i> cell suspensions containing modified coconut fibers were gradually decreased over time. Further, the <i>E.coli</i> solution containing raw coconut fibers showed an approximately similar absorbance variation to the control sample containing the <i>E.coli</i> cells only. The obtained results indicated that the (3-Aminopropyl)triethoxysilane treated DE/PVAc composite coating could be considered as a favorable surface treatment for the coconut fibers for better bacterial accumulation from the aqueous medium.