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 Cu²⁺ and Zn²⁺ 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 Cu²⁺ and Zn²⁺ 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 Cu²⁺ and 99.34% for Zn²⁺ 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 R² = 0.9841 for Cu²⁺ and R² = 0.9927 for Zn²⁺. Likewise, the data were found to fit with a pseudo-second-order model with R² = 0.9989 for Cu²⁺ and R² = 0.9948 for Zn²⁺ 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 Cu²⁺ and Zn²⁺ in aqueous solution. © 2024 Society of Chemical Industry (SCI).