Effective regeneration of an adsorbent for the removal of organic contaminants developed based on UV radiation and toxicity evaluation

Composites of powdered activated carbon and/or titanium dioxide were investigated as a photo-regenerable adsorbent for use in the removal of 2,4,6-trichlorophenol from aqueous solution. Seven types of adsorbents were prepared for organic contaminant adsorption tests. Lab-scale tests were conducted to investigate the removal efficiencies of 2,4,6-trichlorophenol and the potential for regenerating the adsorbents using UV irradiation. Among these adsorbents, the ultrasonic irradiated alginate bead-impregnated powdered activated carbon and titanium dioxide-dry type 1 (PTAB-D-Sonic 1) exhibited the greatest adsorption capacity for 2,4,6-trichlorophenol (12.38 mg g^{- 1}); in addition, the removal efficiency was consistent approximately 11 mg g^{- 1}, notwithstanding repetitive regeneration by UV irradiation. The characteristics of each adsorbent were confirmed using Brunauer-Emmett-Teller (BET), field-emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray (EDX) analysis. In addition, a cytotoxicity experiment was conducted on the developed material, and the results showed that all seven materials had low cytotoxic effects on human cells. This research provides promising results for the application of a photo-regenerable adsorbent, e.g., PTAB-D-Sonic 1, for the removal of various organic contaminants from sewage and wastewater.