五乙烯六胺改性活性炭对Cd的吸附效能

《复合材料学报》优先在线发表论文。

摘  要：以稻壳活性炭(AC)为基体，采用五乙烯六胺(PEHA)为改性剂制备改性AC-PEHA。研究了AC-PEHA对溶液中Cd的吸附动力学、等温吸附曲线、pH的影响等吸附行为，考察了不同HCl浓度对解吸率的影响，并通过SEM、FTIR、BET等手段，对AC、AC-PEHA吸附剂进行了表征。结果表明：AC-PEHA对Cd的吸附在反应时间为60 min处达到平衡，符合准二级吸附动力学模型。在初始Cd浓度为10~350 mg•L-1，pH为5.0的条件下，AC-PEHA对Cd的吸附量达53.58 mg•g-1，显著高于活性炭的吸附量26.15 mg•g-1。初始pH为6~8的条件下，碱性环境更有利于AC-PEHA对Cd的吸附。采用30 g•L-1的HCl对AC-PEHA的Cd解吸率为83.8%。改性后，由于五乙烯六胺进入活性炭孔道，虽然使其孔容、孔径分别降低了21.6%和7.4%，但同时使AC表面负载了伯胺N—H吸附基团，提高了AC-PEHA对Cd的吸附能力。

关键词：Cd；活性炭；五乙烯六胺；吸附；解吸

Abstract: In order to develop an effective adsorbent for Cd removal, activated carbon (AC) was prepared with rice husk and modified with pentaethylenehexamine (PEHA). The batch adsorption were studied for AC and AC-PEHA to determine the effect of contact time, initial cadmium concentration and solution pH on the cadmium ions uptake. The effect of HCl concentration on desorption efficiency for cadmium was discussed as well. SEM, FTIR and BET analysis were used to characterize the structure, morphology and properties of AC and AC-PEHA. The adsorption equilibrium are achieved for both AC and AC-PEHA at react time 60 min, and adsorption kinetics are well described by the pseudo-second-order model. Comparing with AC, The adsorption capacities of AC-PEHA for cadmium increase from 26.15 mg•g-1 to 53.58 mg•g-1 at initial cadmium concentration 10~350 mg.L-1, pH 5.0. The adsorption of cadmium on AC-PEHA is more favourable at alkaline pH (pH 6~8). The maximum cadmium desorption of 83.8% for AC-PEHA occurs with 30 g•L-1 HCl. Although the total pore volume and average pore width of AC decrease by 21.6%, 7.4% respectively after PEHA modification, the modification add more primary amine groups to AC pores, and it significantly enhances the cadmium adsorption capacity of AC.

Keywords: cadmium; activated carbon; pentaethylenehexamine; adsorption; desorption

作者：高秀清等，北京农业职业学院，水利与建筑工程系，北京

通讯作者：高秀清，北京农业职业学院，水利与建筑工程系，北京

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