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 dm 2, 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 R 2 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.