Photooxidation/adsorption of arsenic (III) in aqueous solution over bentonite/ chitosan/TiO2 heterostructured catalyst.

Arsenic contamination of the environment is a serious health hazard due to its toxicity and carcinogenic effects thus demanding developed and robust removal methodologies. In this study, bentonite/chitosan/titania (BT/CS-TiO2) was developed to boost photo-oxidation/adsorption efficiency while providing a low-cost and potential heterostructured platform for arsenic removal from aqueous media. Under UV irradiation, BT/CS-TiO2 heterostructured exhibited the desired capability (97%) of boosting oxidize toxic AsIII to minor toxic AsV. Results confirmed that •OH radicals available at TiO2 sites under UV light played a critical role in the proposed photo-oxidation process of AsIII. BT/CS exhibited a high adsorption capacity (160 mg g-1) for AsV removal due to its electrostatic interaction and surface complexation. Additionally, BT/CS-TiO2 heterostructured showed satisfactory recyclability with no considerable interferences in the presence of coexisting anions due to the suitability of the valence band position of TiO2 for the oxidation of AsIII as well as the presence of CS into BT layers. Thereby, the findings revealed that impregnation of TiO2 in BT/CS is a promising approach for arsenic removal.