Optimization of biosorption potential of nano biomass derived from walnut shell for the removal of Malachite Green from liquids solution: Experimental design approaches

Abstract

Activated carbon based on walnut shell as a biomass material was synthesized and successfully applied for the removal of malachite green (MG) from aqueous solution. Fourier transform infrared spectroscopy, Transmission electron microscopy, Brunauer–Emmett–Teller, Dynamic light scattering and X-ray diffraction were used to characterize the biomass. In batch study, response surface methodology was utilized to screen and optimize key operating parameters with considering removal efficiency as a response. Central composite design was applied to indicate the influence of operating variables including initial concentration of MG (16.5–33.5 mg L−1), nano biomass dose (16.5–33.4 mg) and contact time (13.0–47.0 min) on MG uptake from the aqueous solution. Obtained results showed that about 100% elimination was attained at initial MG concentration of 33.3 mg L−1, nano biomass dose of 33.3 mg and contact time of 20.0 min.Data analysis was done by different adsorption isotherms such as Langmuir, Temkin, Freundlich and Dubinin–Kaganer–Radushkevich (DKR) and the results introduced Langmuir isotherm as a suitable model to define the adsorption behaviors. Finally, the pseudo second order kinetic model described the MG sorption process with a well-fitting (R2 = 0.9897).