Adsorption is a promising contaminant removal method that does not produce any harmful by-products in the treated water. It has also been found to be superior to other drinking water treatment processes in terms of initial cost, flexibility, and ease of operation. However, a major setback of adsorption-based technology is that the used adsorbents need to be either disposed of, or regenerated via a high temperature treatment or acid addition before reuse, creating a substantial amount of waste containing contaminants and spent adsorbent, and resulting in high operation costs.<br/>  In this study, we present composite nanomaterial combining adsorption and photocatalysis, that can undergo photocatalytic regeneration once it has reached its maximum adsorption capacity. The treatment process consists of two steps: first, removal of contaminants using adsorption and second, regeneration of the spent adsorbent using photocatalytic regeneration. Adsorption was selected as the treatment process over photocatalysis, in order to rapidly remove contaminants from the water. Photocatalytic degradation of contaminants involves photon absorption and subsequent generation of hydroxyl free radical species to oxidize contaminants. Here, the photocatalyst (titanium dioxide, P25) is used to degrade contaminants on the adsorbent’s surface, and hence is a sustainable method of regenerating spent adsorbents using solar energy. The adsorbent of interest is layered double hydroxides (LDHs), which are inorganic lamellar compounds considered to be environmentally benign and effective in the removal of dye molecules, due to their hydrophobicity and anion exchange properties. Our results suggest that, after UV-A illumination, the spent composite material can re-adsorb up to 90% of the amount adsorbed by unused composite material.

Adsorption-photocatalysis composite nanomaterials for water treatment

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.