ZIF-8-derived photocatalyst membrane for water decontamination: From static adsorption-degradation to dynamic flow removal

Photocatalysis has been considered a promising method for environmental purification. However, powder nanomaterials are not suitable for large-scale application due to the limit of low recyclability and energy-intensive operation. Integrating and depositing powder photocatalysts on monolithic substrates may solve these issues. In this study, a ZIF-8 photocatalyst membrane and its derived product (ZnS photocatalyst membrane) was constructed by a facile in-situ treatment of cellulose-based substrate (take filter paper as an example). Both the two nanomaterials were confirmed to be tightly anchored to filter paper with the aid of chemical interaction. Under visible light irradiation, excellent dynamic-flow photocatalytic removal efficiencies of methylene blue (MB) degradation (97% within 80 min, k = 0.042 ± 0.002 min^-1) and Cr(VI) reduction (100% within 60 min, k = 0.116 ± 0.007 min^-1) were achieved by the prepared ZIF-8 photocatalyst membrane and its derived ZnS photocatalyst, respectively. Considering the high MB adsorption capacity and facile regeneration process of ZIF-8 photocatalyst membrane, the adsorption-degradation strategy was promising for its universal applications. The MB degradation pathway and photocatalytic mechanisms were also explored. Ultimately, a comprehensive discussion on the advantages and implications of prepared photocatalyst membranes for photocatalytic water treatment was rationally proposed. This study provided a promising method for water decontamination and demonstrated the significant superiority of monolithic membrane for photocatalytic water treatment.