Potential of Borassus aethiopum shells as precursor for activated carbon preparation by physico-chemical activation; optimization, equilibrium and kinetic studies

• Activated carbon was produced from BAS by physico-chemical activation.
• Central composite design was used to optimize three preparation variables.
• The optimum BAS-AC was mesoporous with BET surface area of 795.21 m2/g.
• BAS-AC has maximum adsorption capacity of 219.67 mg/g.
• BAS-AC obeyed Langmuir isotherm model and pseudo-second-order kinetic model.

Optimum activated carbon was prepared by physico-chemical activation from Borassus aethiopum shells (BAS) using CO2 and NaOH as physical and chemical activating agents respectively. It was then evaluated for its ability to remove malachite green dye (MG) from aqueous solution. The effects of solution pH and initial MG concentrations were investigated. Central composite design (CCD), a subset of response surface methodology (RSM) is the statistical technique that was used for the optimization. The conditions optimized were impregnation ratio (IR); activation temperature and activation time with percentage yield and MG percentage removal as the targeted responses. The optimum activated carbon from B. aethiopum shells (BAS-AC) was obtained using the impregnation ratio of 1.33, activation temperature of 713 °C and activation time of 2 h and 49 min. The BAS-AC was mesoporous with surface area of 795.21 m2/g and adsorption capacity of 219.67 mg/g. Langmuir isotherm model gave the best correlation with the experimental data while pseudo-second-order was the best kinetic model that described the adsorption process. Intraparticle diffusion model was applied to determine the mechanism of the adsorption process. BAS was established to be a good precursor for producing activated carbon that is capable of removing high percentage of MG from aqueous solution.

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