Response Surface Optimisation of a Magnetic Activated Carbon Fixed-Bed Column for Chromium and Lead Removal from Wastewater
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Abstract
Fixed-bed systems are more suitable for practical wastewater treatment than batch processes; however, their performance strongly depends on operating conditions. This study optimised a magnetic activated carbon (MAC) fixed-bed column for the simultaneous removal of chromium (Cr) and lead (Pb) from wastewater using response surface methodology (RSM) based on central composite design (CCD). Bed height (8-18 cm) and influent metal concentration (5-30 mg/L) were investigated under two flow rate scenarios (6.30 mL/min and 10.50 mL/min), while adsorption capacity and breakthrough time served as response variables. The developed models showed good agreement with the experimental data, with coefficients of determination (R2) ranging from 0.9445 to 0.9892. Bed height and influent concentration significantly influenced adsorption performance (P < 0.05). Increasing the flow rate from 6.30 to 10.50 mL/min reduced Cr adsorption capacity from 1.96 to 1.17 mg/g and Pb adsorption from 1.61 to 1.11 mg/g, with substantial reductions in breakthrough time. Numerical optimisation identified a model predicted optimum of 18 cm bed height, 11 mg/L influent concentration, and 6.30 mL/min flow rate. The findings demonstrate the potential of MAC for continuous Cr and Pb removal under the investigated operating conditions and provide predictive models and model derived operating conditions for the MAC fixed-bed adsorption system.
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