Effective Copper and Methylene blue adsorption from industrial effluents onto activated carbons prepared from Rice husk ash and Hazelnut husks modified by Diopside: Equilibrium, Kinetics, and Experimental design

Activated carbon from rice husk ash (AC-RH) and hazelnut husks (AC-HH) modified by Diopside (AC-RH/Diop, AC-HH/Diop) composites were synthesised and applied for the adsorption of Copper and Methylene blue from industrial effluents. Diopside was provided by the sol-gel method and activated carbon was prepared from rice husk ash and hazelnut husks. The formation of AC/Diop composites was characterised by FT-IR, FESEM, BET, and XRD analyses. Effects of pH, amount of adsorbent, and contact time at 10 mg L-1 of Copper and Methylene blue on removal percentage were studied by Box Behnken design (BBD). Optimal conditions for maximum Copper and MB by AC/Diop adsorbent (95.54% and 99.42%, respectively) were as follows: (pH = 5.45, 7.35) (adsorbent amount: 0.10, 0.45 g), and (contact time: 9.56, 13.49 min) in 20 mL of 10 mg L-1 of pollutants concentration, respectively. In addition, the adsorption kinetics, thermodynamics, and isotherms were examined. Adsorption isotherms (q(max): 184.25 and 289.51 mg g(-1) for Copper and MB, respectively) and kinetics were demonstrated that the sorption processes were better described by the Langmuir and pseudo-second-order equation.