Roles of adsorption and photocatalysis in removing organic pollutants from water by activated carbon-supported titania composites: Kinetic aspects

Activated carbon-supported titania (ACT) composites were synthesized through a hydrothermal process. Two kinds of titanium precursors (titanium(IV) oxysulfate TiOSO4 liquid and Degussa P25 solid) were used to develop ACT composites (ACT-TiOS and ACT-P25, respectively). The tested amounts of TiOSO4 and P25 were 5 wt.%, 10 wt.%, 15 wt.%, and 20 wt.%. The adsorption capacity and photocatalytic activity of as-prepared composites were explored through the removal of phenol, naphthol blue black (NBB), and reactive black 5 (RB5). The conditions for the occurrence of the synergism of adsorption and photocatalysis in the removals of the three organics by ACT composites were investigated based on their individual kinetics of adsorption and photocatalysis. The results showed that the optimal amount of both titanium precursors used (TiOS-20 and P25) was 20 wt.%. The Brunauer-Emmett-Teller (BET) surface area decreased in the following order: 1316 m(2) g(-1) (activated carbon) > 1101 m(2) g(-1) (ACT-P25-20) > 496 m(2) g(-1) (ACT-TiOS-20). The ACT-TiOS-20 exhibited an anatase phase, whereas the ACT-P25-20 featured anatase and rutile phases. The highest removals of phenol, NBB, and RB5 (initially, 50 mg L-1) after 3 h of UV irradiation were 58%, 95%, and 98% with ACT-TiOS-20, respectively, and 77%, 90%, and 85% with ACT-P25-20, respectively. The reusability study of the ACT composites indicated that the removal efficiencies of phenol after three cycles were similar. (C) 2020 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.