Photocatalytic Cr(VI) reduction over MIL-88A(Fe) on polyurethane sponge: From batch to continuous-flow operation

MIL-88A(Fe)@sponge (MS) was synthesized by a dip-coating method, which displayed efficient photocat-alytic Cr(VI) reduction efficiency under both low power LED UV light and real solar light irradiation. It was observed that MS (0.2 g/L) could remove 100% Cr(VI) (10 mg/L) by adding 0.4 mmol/L tartaric acid (TA) without adjusting pH (pH 5.05) within 6.0 min and 3.0 min under UV light and real solar light irra-diation, respectively. Besides, the photo-induced e- and radicals (O2 center dot-and CO2 center dot -) were found to play the momentous roles in the MS/TA/UVL/Cr(VI) system by the scavenger experiments and electron spin reso-nance (ESR) tests. MS was also filled into a fixed-bed reactor to test the possibility of long-term Cr(VI) reduction operation in TA/UVL system. As expected, the results revealed that MS could still maintain 100% activity up to 60 h. These results demonstrated that MIL-88A(Fe) might be the potentially efficient catalyst for large-scale wastewater treatment in the near future.(c) 2023 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.

Automated summary

MIL-88A(Fe)@sponge (MS) was synthesized using a dip-coating method and demonstrated efficient photocatalytic Cr(VI) reduction under both low power LED UV light and real solar light irradiation. MS (0.2 g/L) in combination with 0.4 mmol/L tartaric acid (TA) achieved 100% removal of Cr(VI) (10 mg/L) within 6.0 min and 3.0 min under UV light and real solar light irradiation, respectively. Furthermore, the photo-induced e- and radicals (O2 center dot- and CO2 center dot -) were found to be vital in the MS/TA/UVL/Cr(VI) system. The results also demonstrated the long-term stability of MS in Cr(VI) reduction, making it a potentially efficient catalyst for large-scale wastewater treatment.