Optimization and adsorption mechanisms of vanadium removal by Fe-Pillared bentonite as an efficient adsorbent

The increasing use of vanadium causes environmental concern about the toxic effluents. In this study, Fe- pillared bentonite (Fe-PB) was synthesized from a domestic clay sample. Characterization ofiron- pillared bentonite by XRF, XRD, FTIR, BET and SEM, indicated the success of the pillaring operation. According to the results, the Fe-PB adsorbent has better properties compared to the NB. In removal experiments, the vanadium removal percentage has been investigated by varying different main parameters including pH (2-10), initial vanadium ion concentration (50-200 mg/L) and adsorbent dosage (1-6 g/L). A combination of Design-Expert software and response surface methodology was applied to determine the influence of each operational parameter on the vanadium removal percentage, optimum condition to reach maximum vanadium removal. Based on the predicted model, maximum vanadium removal onto Fe-PB was 59.96% on the optimum operational condition as pH = 5.82, initial vanadium concentration = 50 ppm and adsorbent dosage = 6 g/L at 3 h contact time. Equilibrium data were best described by Langmuir model, and analysis of kinetic data demonstrated that the pseudo-second-order model accurately represents the kinetic data.