Dye Adsorption Study of ZIF-67 Mesoporous Composite with Strong Hydrophobic Effect in Low-Temperature Aqueous Environment

In this study, a novel mesoporous adsorption composite namely G-SMS/ZIF-67(C) was synthesized by coating the ZIF-67 doped with graphene oxide (GO) on the surface of spherical mesoporous silica (SMS) and finally modified by high-temperature calcination. Compared with activated carbon (AC), the synthesized adsorption composite exhibited a good adsorption capacity of methyl orange (MO) in low-temperature aqueous environment. The adsorption process was consistent with the pseudo-first-order kinetics and Freundlich model. It revealed that the formed mesoporous structure and hydrophobic interactions of the G-SMS/ZIF-67(C) after calcination effectively improved the adsorption performance, with the average adsorption rate and maximal adsorption capacity of G-SMS/ZIF-67(C) 1.8 and 2.91 times higher than that of the ones without calcination, respectively. Moreover, the maximal adsorption capacity of the G‑SMS/ZIF-67(C) composite was positively correlated with the temperature. The thermodynamics and mechanism of the adsorption process have been investigated and rationalized.