Evaluation of Cr(VI) adsorption on glutaraldehyde crosslinked chitosan beads using cyclic voltammetry employing gold electrode

Abstract

Hexavalent chromium is one of the toxic heavy metals found in wastewaters from industries like electroplating, leather tanning, and steel manufacturing. The Cr(VI) removal and quantitative detection are among the major concerns from an environmental toxicity point of view. In the present work, we report an effective electrochemical technique for Cr(VI) monitoring based on the utilization of gold electrode. The technique developed is user-friendly, non-destructive, and provides real-time monitoring of Cr(VI) from wastewaters in contrast to other spectroscopic and optical techniques. The technique developed was applied in monitoring Cr(VI) removal from synthetic Cr(VI) samples using chitosan cross-linked glutaraldehyde (C + G) beads. The parameter optimization for Cr(VI) removal using C + G beads was done. The experimental data of Cr(VI) adsorption on C + G beads obtained using cyclic voltammetry were further used for kinetic and thermodynamic studies. Kinetic and thermodynamic studies found that Cr(VI) adsorption follows pseudo-second-order kinetics and Modified Langmuir isotherm. The maximum adsorption capacity of C + G beads for Cr(VI) was found to be 28.65 mg g−1. These results obtained indicate that the cyclic voltammetric technique using gold electrode can be effectively applied for Cr(VI) analysis from wastewaters.

Cr(VI)-Mediated Homogeneous Fenton Oxidation for Decolorization of Methylene Blue Dye: Sludge Free and Pertinent to a Wide pH Range

“…Cyclic voltammogram of Cr­(VI)+MB before the addition of H 2 O 2 showed a single cathodic signal at −0.5 V and a single anodic signal at −0.32 V. After the degradation of MB in the Cr­(VI)/H 2 O 2 system, anodic and cathodic peaks at −0.5 and −0.32 V disappeared, indicating the complete degradation of MB. Cyclic voltammograms of Cr­(VI)+MB in the presence and absence of H 2 O 2 were recorded using KNO 3 as the supporting electrolyte and glassy carbon electrode as the working electrode in the potential range of 0.3 to −0.8 V versus Ag/AgCl as the reference electrode, with a scan rate of 0.1 V/s. , Only MB’s anodic and cathodic signals are obtained using the conditions mentioned above, and Cr­(VI) signals do not interfere with MB signals.…”