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

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.