Adsorption of bimetal from aqueous solution on plum seed activated carbon synthesized by pyrocarbonic acid microwave method

BACKGROUND This article presents the simultaneous adsorption of bimetal Cu 2+ and Zn 2+ from an aqueous solution using activated carbon synthesized from a plum seed precursor by sulfuric acid and microwave activation: plum seeds chemically activated by 45% (w/w) sulfuric acid with 2:1 ratio for 4 h, then carbonized for 2 h at 700 °C and the product obtained activated in a microwave oven for 20 min at 700 W for final of activation. Plum seeds and activated carbon produced were characterized in terms of their physical and chemical composition using Brunauer–Emmett–Teller measurements, field emission scanning electron microscopy and Fourier transform infrared spectroscopy. The effects of absorption time, bimetal solution pH, bimetal concentration and dosage of activated carbon on the capacity of adsorption and removal efficiency were studied with Design‐Expert software using response surface methodology with the I‐optimal method for experimental data analysis. RESULTS The results showed that the statistical analysis of Cu 2+ and Zn 2+ removal efficiency followed the quadratic models generated by Design‐Expert software with significant P value ( P < 0.0001) and the optimum values of removal efficiencies were 99.9268% for Cu 2+ and 99.34% for Zn 2+ at an adsorption time of 4.98 h, pH of 7.94, bimetal concentration of 38.467 mg L −1 and adsorbent dose of 1485.294 mg (100 mL) −1 . The equilibrium adsorption data were analyzed by Langmuir and Freundlich isotherm models and there was a significant agreement in the results with the Freundlich model with R 2 = 0.9841 for Cu 2+ and R 2 = 0.9927 for Zn 2+ . Likewise, the data were found to fit with a pseudo‐second‐order model with R 2 = 0.9989 for Cu 2+ and R 2 = 0.9948 for Zn 2+ as compared to a pseudo‐first‐order model. CONCLUSION Activated carbon synthesized from plum seeds with chemical and microwave activation could be effectively used as an adsorbent for bimetal Cu 2+ and Zn 2+ in aqueous solution.