Photocatalytic Inks Based on TiO₂ Nanomaterials for Water Remediation

Wearable devices are a current reality and its development deserves great attention. Transferring the properties of nanostructures into textiles could have a great impact on society’s every day life. Moreover, heterogeneous photocatalysis has gained attention in recent years as a method to clean water, due to its great potential for the mineralization/breakdown of organic pollutants via advanced oxidation processes (AOP) [1]. Most materials used for research in this field are employed in either powder form or supported over a rigid substrate, both of which are unsuitable for large-scale applications. Our work aims to evaluate the photocatalytic efficiency of textiles printed with screen-printable inks based on TiO₂ nanomaterial pigments, proposing them as a promising alternative for large-scale remediation of water bodies.<br/>A screen-printing paste has been designed with a commercially available TiO₂ powder (80% anatase; 20% rutile) used as the active pigment. A second set of TiO₂-based materials were obtained via the reduction of the commercial powders in presence of Al, following a procedure reported by Wang et al. [2]. These pastes were obtained by mixing the pigments with polymeric binders and a plastifier, using a mixture of water and ethanol as solvent. As-obtained pastes/inks were used to screen-print patterns onto different textile substrates. Angle-contact measurements of the different pastes were analyzed to explore their wettability properties, while microscopic profiles of the cross section of the dried patterns allowed to monitor and optimize their viscosity. The TiO₂-based inks exhibited good viscosity for screen-printing onto cotton and glass fiber substrates. The adherence and physical stability of the printed patterns has been evaluated.<br/>Photocatalytic tests were performed via the degradation of a dye under various light conditions in presence of the screen-printed textiles and compared to the pigments in their powder form as reference. This result should be important data to evaluate the performance at a laboratory level for the use of TiO₂-based inks in large-scale water remediation.<br/><br/>References<br/>[1] Mills, A., Davies, R., Worsley, D., Water purification by semiconductor photocatalysis. Chem. Soc. Rev., Vol 22, 417-425 (1993).<br/>[2] Wang et al. Visible-light photocatalytic, solar thermal and photoelectrochemical properties of aluminium-reduced black titania. Energy and Environmental Science, 6(10), pp. 3007–3014 (2013).<br/><br/>Acknowledgments<br/>We would like to thank financial support from the DGAPA-UNAM through PAPIIT project IN111223 and UI/UNAM System Joint Research Collaboration program project. We thank Francisco Ruíz, Eduardo Murillo, David Dominguez, Eloísa Aparicio, Israel Gradilla, Jesús Díaz and Jaime Mendoza for technical support and all the AG&P groupmates for fruitful discussions.