Comparison of Chitosan-Based Biocomposites for Remediation of Water with Cr(VI) Ions

Abstract

Chitosan/fly ash (CFA) and chitosan/activated carbon (CAC) biocomposites were compared in terms of their performances for the removal of Cr(VI) ions from aqueous solutions. SEM and FTIR images of both new synthesized adsorbents were also obtained. The removal of heavy metal ion was carried out via batch adsorption process and the effects of parameters such as amount of adsorbent (0.01-0.1 g), contact time (5-180 min), pH (1.0-5.0) and initial concentration (5-50 ppm) on adsorption were investigated. Both biocomposites had reached equilibrium in 30 minutes at a pH value of 3.0. The experimental data were evaluated in terms of isotherm models and it was indicated that Freundlich isotherm well fitted to the data. The maximum adsorption capacities of CFA and CAC were found as 23.6 and 24.4 mg/g, respectively. The adsorption process for Cr(VI) removal by CFA and CAC was also investigated in terms of kinetics models. It was found that both adsorbents were in accordance with pseudo-second kinetics model and the related coefficients were calculated. It was determined that the biocomposites had higher efficiency for the removal process and when the performance of both biocomposites was compared, CFA, as a more natural residue based sorbent, had a removal performance close to that of CAC.