Enhanced Pb (II) removal from aqueous solutions via electrocoagulation using corncob biochar as a support: A RSM study

Abstract

This study explores the enhanced removal of Pb(II) from aqueous media using a hybrid Electro coagulation (EC) system featuring aluminum electrodes supplemented by corncob-derived biochar (CCBC). By repurposing agricultural waste into a high-value adsorbent, this integrated approach aims to improve electrochemical treatment performance. Characterization of the synthesized CCBC via XRD, FTIR, TGA, and pHPZC confirmed its structural crystallinity, functional group distribution, and thermal resilience. Using Response Surface Methodology (RSM) with a Central Composite Design (CCD), we optimized critical variables including pH, initial lead concentration, reaction duration, and current density. ANOVA results validated the model's robustness, yielding R 2 values of 0.9860 and 0.9434. Comparative analysis revealed that while standalone EC and CCBC achieved removal rates of 96.7% and 97.45% respectively, the integrated EC–CCBC system exhibited superior buffering capacity against high-concentration pollutants. Under optimized conditions pH 8.12, 37.35 min reaction time, and a current density of 0.46 A/m −2 the hybrid system reached a peak removal efficiency of 98.16% for an initial concentration of 374.74 mg/L. The primary mechanisms identified include the entrapment of lead within Al(OH) 3 flocs during electrochemical precipitation, alongside microporous adsorption by biochar surface groups. Furthermore, cathode-driven hydrogen evolution enhanced solid-liquid separation via flotation. These results indicate that the EC–CCBC configuration provides a sustainable and potent solution for remediating heavy-metal-laden industrial effluents.