The feasibility of coconut shell charcoal (CSC) and commercial activated carbon (CAC) for Cr(VI) removal was investigated in batch mode using synthetic electroplating wastewater by Babel and Kurniawan [196]. Surface modifications of CSC and CAC with chitosan and/or oxidizing agents, such as sulfuric acid and nitric acid, respectively, were also conducted to improve removal efficiency. It was reported that both CSC and CAC, which were oxidized with nitric acid, showed higher Cr(VI) adsorption capacities (CSC: 10.88, CAC: 15.47 mg/g) than those oxidized with sulfuric acid (CSC: 4.05, CAC: 8.94 mg/g) and non-treated CSC coated with chitosan (CSCCC: 3.65 mg/g). It was suggested by them that surface modification of carbon adsorbent with a strong oxidizing agent generates more adsorption sites on their solid surface for metal adsorption.