Corn cobs and KOH-treated biomasses for indigo carmine removal: kinetics and isotherms

In this work, indigo carmine (IC) removal with corn cob (NCC) and KOH-treated (MCC) biomasses were studied. The removal efficiency (%R) was maximized by varying adsorbent dosages (D), initial concentrations ( C 0 ), and pHs. Therefore, D of 4 and 5 g L −1 at 50 mg L −1 of C 0 and pH 2 maximized % R for NCC (70%) and MCC (71%). The KOH-based chemical modification significantly enhanced the pore sizes and the point of zero charge. Moreover, the site’s availability also increased. Chemisorption, including adsorbate-adsorbate interaction, addressed kinetics according to the pseudo-second-order and Elovich models. The Langmuir model fit well with the isotherm data suggesting that the process is thermodynamically favored for NCC. Electrostatic interactions, hydrogen bonds, and π-related interactions mainly conducted the adsorption process. The optimum adsorption capacities showed that NCC (19.87 mg·g −1 ) was more efficient than MCC (15.59 mg·g −1 ) and several reported biomass-based adsorbents. These results suggest that corn cob biomass is a promising low-cost adsorbent to bioremediate IC.