Low-cost activated carbon: characterization, decolorization, modeling, optimization and kinetics

Grape wood activated carbon (GWAC) as a cost-effectiveness and nontoxic adsorbent was developed for methylene blue (MB) removal from aqueous solutions. The adsorbent was characterized using SEM, BET, FTIR and pH(ZPC). Design of experiments, modeling and optimization of data were carried out using central composite design through response surface methodology. The effects of the main variables including initial dye concentration (100-500 mg/L), pH (3-11), contact time (10-90 min) and adsorbent dosage (0.25-12.25 g/L) on the decolorization were investigated using analysis of variance (ANOVA). The efficiency of MB removal increased to more than 98.5% with increasing pH and contact time from 3 to 11 and 10 to 90 min, respectively, under 0.25-12.25 g/L of GWAC. The experimental data were fitted to Langmuir model (R-2 = 0.98), and the maximum adsorption capacity (q(max)) was 4.82 mg/g. The adsorption kinetics were well described by the pseudo-second order (R-2 = 0.9485). This study highlighted grape wood waste as a suitable adsorbent with high efficiency for the removal of methylene blue from water and wastewater.