Optimization of chemical modification process of activated carbon surface with iron nanoparticles for efficient vanadium removal: Kinetics, equilibrium and surface complexation modelling

This research deals with the chemical modification of activated carbon surface with the iron functional groups to enhance the adsorption ability. The modification process was optimized and the effects of three factors (temperature, reaction time, and iron concentration) on the removal abilities of iron impregnated activated carbon (I-AC) adsorbents were investigated. The adsorbent prepared at optimum conditions (I-AC-OP) was able to remove about 99.70% of vanadium in 3 h. The iron impregnated adsorbents were characterized using different techniques. Acid-base titrations of activated carbon and I-AC-OP were performed and the surface charge characteristics of adsorbents were determined using FITEQL software. The effects of pH, ionic strength, time and temperature on vanadium removal abilities of adsorbents were evaluated in batch method. Experimental data showed that ionic strength had no influence on vanadium removal. The experimental data of vanadium (V) removal in various pH was modelled by diffuse double layer model (DDLM) using FITEQL software. The results demonstrated that the DDLM is able to fit the removal process in the pH range measured. The kinetic data suggested that chemical adsorption was the controlling step for vanadium removal process, rather than the mass transfer. The maximum adsorption capacity of I-AC-OP for vanadium was 81.96 mg.g(-1).