Catalysis Today, Vol.341, 26-36, 2020
Degradation of emerging contaminants diclofenac, sulfamethoxazole, trimethoprim and carbamazepine by bentonite and vermiculite at a pilot solar compound parabolic collector
This study was aimed at evaluating bentonite (BEN) and vermiculite (VER) clays as photoactive materials for photodegrading a low-concentration (100 mu g L-1) mixture of four emerging contaminants (ECs): trimethoprim (TMP), sulfamethoxazole (SMX), carbamazepine (CBZ) and diclofenac (DCF), using a solar advanced oxidation process. The experiments were performed in a stirred magnetic batch reactor (SMBR) and a solar pilot plant compound parabolic collector (CPC). The effect of mass, type of catalyst clay and H2O2 dose were evaluated, and the photodegradation of ECs was followed by Ultra Performance Liquid Chromatography (UPLC) and Dissolved Organic Carbon content (DOC). The results showed that the optimal dose of clays for EC degradation in both SMBR and CPC reactors was 0.2 g L-1. The photodegradation of ECs at optimal conditions by BEN and VER in the CPC decreased in the following order: DCF > TMP > SMX > CBZ and DCF > SMX > TMP > CBZ, respectively. The photodegradation rate constants for VER were 2, 32 and 1.1 times higher than those for BEN when SMX, CBZ and DCF were photodegraded with the optimal dose of clay, correspondingly. The percentage removal of DCF and SMX in experiments using BEN or VER was similar to TiO2. The TMP, SMX, CBZ and DCF degradation rate constants increased 9.05, 18.9, 2.08 and 23 times by adding [H2O2]= 200 mg L-1 and VER. The percentage removal of DOC was 16, 40 and 48% when VER and 50, 100 or 200 mg L-1 of hydrogen peroxide were added into the system, respectively. Similar results were obtained by adding BEN.