Removal of chromium from textile wastewater using corncob-derived activated carbon in an industrial case study at MAA garment

Abstract

Rapid industrialization unleashes toxic hexavalent chromium (Cr(VI)) from textile effluents into waterways, threatening ecosystems and human health in water-stressed regions like Ethiopia. This study harnesses abundant corncob waste to fabricate chemically activated carbon (CCAC) via KOH impregnation and pyrolysis, optimizing Cr(VI) removal from real post-biological wastewater of MAA Garment Factory, Mekelle (initial 1.35 mg/L Cr(VI)). Batch experiments using response surface methodology (central composite design, 29 runs) identified optimal conditions: 0.175 g/L dosage, pH 6.5, 75 min contact time, 200 rpm achieving 99.45% removal (residual < 0.007 mg/L, below WHO/EPA limits) and Langmuir qₘ of 515.5 mg/g (R²=0.999). Pseudo-second-order kinetics and FTIR/SEM confirmed chemisorption via -OH/C = O groups on porous surfaces, outperforming many biomass adsorbents. This low-cost, regenerable solution advances circular economy principles, directly supporting SDGs 6 (clean water), 9 (innovation), and 12 (waste valorization). Pilot scaling and multi-metal tests promise industrial viability for sustainable wastewater polishing.