Novel adsorbent for malachite green from okra stalks waste: synthesis, kinetics and equilibrium studies

In this study, malachite green (MG) removal was performed with activated carbon synthesized from okra stalks by microwave assisted chemical activation method. In the synthesis of activated carbon, the effects of gas in the microwave, activation, and impregnation rate were investigated. The synthesized activated carbon characterization was investigated using BET, FT-IR, and SEM analyses. The activated carbon surface area achieved was 759.453 m² g⁻¹. In addition, the surface area of activated carbon synthesized using the conventional method was17.766 m² g⁻¹. The effect of the initial solution concentration on MG adsorption was investigated. According to the kinetic and equilibrium data, it was found that the adsorption process best fitted the pseudo-second order kinetic model and the Langmuir isotherm. According to the equilibrium data, the maximum adsorption capacity (q _max) of the monolayer was 119.05 mg g⁻¹. In addition, MG adsorption was investigated by the experimental design method. The adsorption capacity at the determined optimum conditions was 99.63 mg g⁻¹. All results show that activated carbon synthesized from waste biomass by combining the conventional method with microwave-assisted impregnation is a cheap and environmentally friendly adsorbent.