Recent advances on ZIF-8 composites for adsorption and photocatalytic wastewater pollutant removal: Fabrication, applications and perspective

Zeolitic imidazolate framework-8 (ZIF-8), which consists of metal atom Zn and 2-methylimidazole, is a kind of typical MOF materials. The unique properties of ZIF-8 endue it superior adsorption capacity and good host ability for photocatalytic materials, which makes it be a high-profile material in the treatment of wastewater. However, ZIF-8 particles tent to aggregate together and result in the decrease of specific surface area. They also suffer from weak recyclability, as it is hard to separate them from water after removing pollutant. The newly emerging ZIF-8 composite materials solve the above problems, and are successfully applied in wastewater treatment. In this review, the current design and synthesis methods of ZIF-8 composites are systematically summarized. The recent research progress of ZIF-8 composites as adsorbents and photocatalysts to remove wastewater pollutants is critically introduced. Different factors affecting its efficiency and the mechanism of pollutant removal are also discussed. This review attempts to lay the mechanistic insight for the application of ZIF-8 composite in practical wastewater treatment and provides new ideas for constructing high-efficient ZIF-8 based adsorbent and photocatalyst. For the purpose of revealing the whole potentiality of ZIF-8 composite in pollutants removal and water regeneration, current challenges are introduced and future research directions are proposed at last.