ZIF-based zinc titanate composite as sufficient sorbent for removal of Congo red from aqueous solutions

Abstract

Zeolite imidazolate frameworks (ZIFs) are new subclass of MOFs and have highly porous structure. Zinc titanate and zinc titanate @ ZIF nanocomposite were prepared and characterized by FTIR, SEM, TEM and XRD methods. The FTIR and XRD results showed formation of zinc titanate and zinc titanate @ ZIF. The SEM and TEM results also indicated porous nature with particle size 50 and 60 nmfor Zinc titanate and zinc titanate @ ZIF nanocomposite, respectively. Zinc titanate and zinc titanate @ ZIF possessed surface area 10.5 m2 g-1 and 115 m2 g-1, respectively. They were used for removal of CR from aqueous solutions. The optimum conditions for CR removal were occurred for 40 mg L-1 of CR at pH 6 and contact time 60 min and 10 min for zinc titanate and zinc titanate @ZIF, respectively. The adsorption kinetics of CR was described by pseudo second order kinetic model. Langmuir isotherm model best described the equilibrium adsorption of CR than Freundlich and Temkin isotherm models. The desorption studies showed that the regeneration of the zinc titanate@ZIF adsorbent can be easily attained by heating to 300 ºC.