Abstract
A water stable and hybrid nonporous adsorbent, cubic zeolitic imidazolate framework-8 (ZIF-8), was synthesized for Acid orange 7 (AO7) removal from aqueous solutions in batch mode. Central composite design was utilized to explore the individual and interaction effects of pH, AO7 concentration, ZIF-8 dosage and contact time on dye adsorption. A second order polynomial equation (R(2) = 0.9852, LOF = 0.1419) developed for prediction of the AO7 removal. Sorption model revealed that the adsorbent dosage and the dye concentration are major factors that controlled the AO7 removal efficiency. AO7 removal increased from 55 to 80% by increasing ZIF-8 dosage from 0.2 to 1 g/L. The dye removal, on the other hand, decreased from 84 to 70% with increasing AO7 concentration from 10 to 100 mg/L and increased from 60% to 80% by decreasing pH from 12 to 4. The dye removal followed the pseudo second order kinetic and the Langmuir isotherm model. The maximum monolayer adsorption capacity of 80.47 mg dye/g of ZIF-8 was obtained according to the Langmuir model.