Facile fabrication of UiO-66-NH2 modified with dodecyl and polyethyleneimine by post-synthesis functionalization strategy and simultaneous adsorption removal of anionic and cationic dyes

Abstract

To achieve simultaneous adsorption removal of anionic and cationic dyes, UiO-66-NH2@Dodecyl functionalized with dodecyl (long-chain alkane) and UiO-66-NH2@PEI modified by polyethyleneimine (PEI) (containing multiple amino groups) were facilely fabricated by post-synthesis functionalization strategy, and characterized systematically. UiO-66-NH2@Dodecyl and UiO-66-NH2@PEI both showed higher adsorption capacities for Congo red (458.2 and 583.4 mg/g) and methylene blue (218.0 and 286.3 mg/g). Adsorption kinetic and isotherm curves could be simulated best by pseudo-second-order kinetic model and Langmuir isotherm model, respectively. Under coexistence of inorganic salts and alkalinity, it was beneficial to improve adsorption capacities. Adsorption capacity of UiO-66-NH2@PEI with multiple amino groups was higher than UiO-66-NH2@Dodecyl at the same experimental conditions, indicating that hydrogen bonding had greater influence on adsorption efficiency. And UiO-66-NH2@Dodecyl and UiO-66-NH2@PEI had better stability. Hydrogen bonding, π-π conjugation, electrostatic interaction and van der Waals force were main adsorption driving forces. The results could provide theoretical and technical help for simultaneous adsorption removal of anionic and cationic dyes.