微波制备龙眼壳活性炭及其对Pb^(2+)的吸附与再生

Adsorption and Regeneration of Lead Ions on Activated Carbon Prepared from Dimocarpus Longan Shell by Microwave Radiation

以龙眼壳为碳源,氢氧化钾为活化剂,微波辐射法制备活性炭,并考察其对二价铅离子的吸附平衡、动力学及再生研究.制备活性炭的最佳条件为:浸渍时间24 h,辐射时间12 min,微波功率720 W和活化剂浓度20%,该条件下活性炭的碘吸附值为1247.4 mg/g,亚甲基蓝吸附值为98.1 m L/g,比表面积为1011.7 m^2/g,总孔容为0.543 cm^3/g,平均孔径为2.146 nm.吸附研究表明:二价铅离子在龙眼壳质活性炭上的吸附行为较好地服从Langmuir等温吸附模型和准二级动力学模型,平衡时间为30 min,最大平衡吸附量为71.06 mg/g.活性炭在5次再生回用后仍保持在首次吸附量的83.5%,该活性炭再生能力较好,可进一步降低重金属的处理成本.

The microporous activated carbon was prepared by microwave radiation using longan shell and KOH as carbon source and activator, respectively. The adsorption equilibrium, kinetics and regeneration of activated carbon for lead ions from aqueous solution were investigated. The optimum preparation conditions were as follows： impregnation time of 24 h, radiation time of 12 rain, microwave power of 720 W and KOH concentration of 20%. Under the optimum conditions, the iodine adsorption value was 1247.4 mg/g, the methylene blue adsorption value was 98,1 mug, the BET surface area was 1011.7 m＇-/g, the total pore volume was 0.543 em3/g and the average pore width was 2.146 nm. Batch adsorption study showed that the adsorption experimental data tended to be fitted well by Langmuir isotherm model and pseudo-second-order kinetic model, the equilibrium time was 30 rain, and the maximum Langmuir adsorption capacity was 71.06 mg/g. Moreover, the regenerated activated carbon remained 83.5% of the initial adsorption capacity for lead ions after five adsorption/ desorption cycles. The good regenerability of this activated carbon can further reduce the treatment cost of heavy metals.