Post-synthetic functionalization of UiO-66-NH2 by polyacrylamide and polyvinylimidazolium salt brushes via ATRP and adsorption behavior

Abstract

Aquacultural water pollution caused by methylene blue is an urgent environmental problem, posing a serious threat to aquaculture and human health. Adsorption is a potential and promising method to remove methylene blue from aquaculture water. In this study, UiO-66-NH2@PAM and UiO-66-NH2@PVIO post-synthetic functionalized by polyacrylamide and polyvinylimidazolium salt brushes onto UiO-66-NH2 by virtue of ATRP method were successfully synthesized, and adsorption performance for methylene blue were systematically studied. Adsorption kinetic curves with trend of first increase, and decrease, and then increase was explained by capillary effect. Experimental data were fitted best by pseudo second-order kinetic and Langmuir isotherm model. UiO-66-NH2@PVIO had comparatively higher adsorption capacities than UiO-66-NH2@PAM, because UiO-66-NH2@PVIO had stronger adsorption affinity and binding energy for methylene blue than UiO-66-NH2@PAM. Adsorption driving forces were electrostatic interaction, π-π conjugation effects, hydrogen-bonding interactions, induced dipoles, van der Waals forces, sieving effect so that adsorption processes were ascribed to physical adsorption. UiO-66-NH2@PAM and UiO-66-NH2@PVIO had very good reusability and stability, and could be utilized in practical application. The results can offer better help for the synthesis of MOF materials by the technology of post-synthetic functionalization, and provide technical guidance for actual application in dye removal from aquacultural water.