Optimization of microwave preparation conditions for activated carbon from Albizia lebbeck seed pods for methylene blue dye adsorption

•Albizia lebbeck seed pods were used as precursors for activated carbon.•The optimum preparation conditions were determined using RSM technique.•High surface area of 1824.88 m2/g was characterized.•Maximum methylene blue capacity of 381.22 mg/g was reported.•The kinetic data were well described by pseudo-second order model.

Microwave assisted KOH activation has been utilized for preparation of activated carbon from agricultural wastes, Albizia lebbeck seed pods. The surface area, micropores volume, and mesopores volume of this carbon (KAC) were 1824.88 m2/g, 0.645 cm3/g, and 0.137 cm3/g, respectively. The effects of process variables represented by radiation time, radiation power, and impregnation ratio on the yield and methylene blue (MB) uptake of such carbon were studied. Box-Wilson central composite design was adopted to arrange the experiments and two second order polynomial models were developed to correlate the process variables to the two responses. MB uptake of 220.83 mg/g and 22.48% carbon yield were reported at optimum preparation conditions. The best fitting for MB experimental equilibrium data was achieved with the Langmuir isotherm, giving a maximum MB adsorption capacity of 381.22 mg/g. The experimental kinetic data were well described by the pseudo-second order model.