Mechanism and Kinetics of Cr(Vi) Adsorption on Carbon Derived from Citrobacter Freundii Under Different Pyrolysis Temperatures

Use of bacterial biochar for Cr(VI) removal opens room for new research in terms of cost effectiveness, better performance and high selectivity. This work reports the synthesis, physicochemical characterization and performance evaluation of bacterial biochar synthesized at 200oC and 400oC. To examine the removal mechanism and behavior, batch mode experiments were conducted by modifying different parameters such as dosage, pH, initial ion concentration and temperature. The capacity of the biochar for removing Cr(VI) was found to be qmax = 19.43 mg/g (200o C) and 29.73 mg/g (400o C). The BET surface area bacterial biochar (400o C) is also seen to decrease from 22.09 m2/g to 3.17 m2/g. The decrease in pore volume and surface area makes successful adsorption evident. In addition to this, the adsorption data were adequately simulated with Langmuir, Freundlich and Temkin and pseudo second kinetics suggesting that adsorption process were the combination of external mass transfer and chemisorption. Electrostatic interactions were determined to be the dominant removal mechanism. Biochar pyrolyzed at 400o C serve as good adsorbent material for removal of Cr(VI) from aqueous solutions. It can also be a suitable material for the removal of emerging contaminants from aqueous solutions