Integrated adsorption and visible-light photodegradation of aqueous clofibric acid and carbamazepine by a Fe-based metal-organic framework

Abstract

The development of efficient materials for removing pharmaceuticals from water has been a matter of great concern. As a new class of porous materials, metal-organic frameworks (MOFs) have attracted considerable attention in the field of environmental remediation. In this article, a photocatalytic adsorbent MIL-53(Fe) was successfully prepared by solvothermal method and used for the removal of two typical pharmaceuticals clofibric acid (CA) and carbamazepine (CBZ) from water. MIL-53(Fe) exhibited good adsorption performance and the maximum adsorption capacities of CA and CBZ are about 0.80 mmol/g and 0.57 mmol/g, respectively. The adsorption mechanisms of CA and CBZ are mainly due to electrostatic interaction and π-π interaction, respectively. Further, MIL-53(Fe) exhibited high photocatalytic activity and stability under visible light. The photocatalytic efficiency could be improved significantly with the addition of a small amount of H_2O_2, and the corresponding photodegradation efficiencies for CA and CBZ both reached up to 90%, which are higher than those of Fe(II)/H_2O_2 and TiO_2 under visible light. The photocatalytic performance was strongly dependent on the solution pH. The Fenton-like reaction, charge carriers directly generated in the photo-excited MIL-53(Fe) and the synergistic effect of H_2O_2 were the main mechanisms. The formation of humic acids-like and fulvic acids-like organic matter in the degradation process was detected by 3D EMMs. MIL-53(Fe) also revealed excellent performance for the removal of CA and CBZ from real municipal wastewater and river water. Therefore, MIL-53(Fe) may be used as a promising photocatalytic adsorbent for wastewater purification.

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