Removal of Chromium from Aqueous Solutions by Treatment with Carbon Aerogel Electrodes Using Response Surface Methodology

An electrochemical process using carbon aerogel electrodes was developed to treat chromium-contaminated waters. The operational conditions viz. pH (2-7), initial metal ion concentration (2-8 mg/L), and charge (0.3-1.3 A h) were optimized to achieve maximum removal efficiency. The dimensions of the cell and electrode area were 1.8 dm (length) * 0.75 dm (breadth) * 0.95 dm (height) and 0.54 dm2, respectively. In the experiments, chromium concentration dropped from 2 mg/L to 0.008 mg/L (99.6% removal) under optimized conditions of pH 2 and 0.8 A h. To optimize the flow rate, experiments were carried out at different flow rates (60-600 L/h) in the electrochemical reactor. Batch experiments were designed by response surface methodology using Box-Behnken design, which can be used to optimize the key parameters for maximizing the removal percentage. An R2 value of 0.9736 was obtained from the regression analysis of the performed experiments which exhibited a close fit between the experimental results and model predictions.