68 / 2016-04-28 22:02:02

Photocatalytic Degradation of Methylene Blue in ZIF-8

photocatalysis,ZIF-8,methylene blue,pathway,222

Metal–organic frameworks (MOFs), a new class of porous crystalline materials, have attracted great interest as a promising candidate for sustainable energy and environmental remediation. In this study, ZIF-8, a versatile MOF based on imidazolate ligands, was selected as photocatalyst to decompose methylene blue (MB) under UV light irradiation. The influence factors, kinetics, and mechanism of photocatalytic MB degradation and stability of ZIF-8, were also studied. The results revealed that ZIF-8 photocatalyst exhibited efficiently photocatalytic activity for MB degradation under UV irradiation, which was confirmed through the detection of hydroxyl radicals (•OH) by fluorescence method. The MB degradation over ZIF-8 photocatalyst followed pseudo-first-order kinetics model. ZIF-8 worked effectively over a wide pH range from 4.0 to 12.0, and showed both high adsorption capacity and degradation efficiency for MB in strong alkaline environment. The enhanced efficiency in strong alkaline environment was resulted from the higher charged ZIF-8 (pH > pHpzc) and the elevated yield of •OH facilitated by increased OH- concentration. The possible pathway of photocatalytic degradation of MB in ZIF-8 was proposed. The results indicated that ZIF-8 can be used as a high efficient photocatalyst to decompose organic pollutants.