Removal of Reactive Blue 21 from Aqueous Solution Using Activated and Non-Activated Carbon Prepared from Agricultural by-Products

Activated carbon derived from sesame stalk (SS) and wheat straw (WS) was explored as a low-cost adsorbent for the removal of reactive blue 21 (RB21) dye from aqueous solutions. The activated carbons (AC) were prepared by chemical activation using KOH. The effects of pH, contact time, dye concentration, and adsorbent dose on RB21 removal were studied in batch experiments. The optimum adsorption occurred at pH 1.0 for both activated (AC) and non-activated (NA) carbons. The maximum adsorption capacities were determined to be 2.9 mg g-1 for ACSS, 3.44 mg g-1 for ACWS, 2.6 mg g-1 for NACSS, and 2.7 mg g-1 for NACWS, respectively. The adsorbents removed RB21 from textile wastewater, achieving removal efficiencies ranging from 72 to 88%. Adsorption kinetic data were analyzed using the pseudo-first and pseudo-second orders. It was found that the adsorption of RB21 dye onto activated and non-activated carbon followed second-order kinetics. Equilibrium adsorption data were analyzed using Langmuir and Freundlich isotherms. The experimental data were better fitted to the Freundlich isotherm model within the investigated experimental conditions. The results revealed that the activated carbon from SS and WS are effective, low-cost materials for removing RB21 dye, offering a potential efficient treating of textile wastewater.