赤泥-海藻酸钠水凝胶对水中Pb(Ⅱ)的吸附性能

Adsorption Performance of Red Mud-Sodium Alginate Hydrogel on Pb(Ⅱ)in Water

以赤泥和海藻酸钠为原料,采用交联反应的方法制备赤泥-海藻酸钠水凝胶(RMSA)。通过批量实验考察溶液初始pH、吸附温度、吸附时间、初始浓度以及多元重金属体系对RMSA吸附Pb(Ⅱ)效果的影响,并结合XRD、FTIR和SEM-EDS表征分析,研究其对Pb(Ⅱ)的吸附特性。实验结果表明,拟二级动力学吸附模型和Langmuir吸附等温模型能够更好地描述RMSA对Pb(Ⅱ)的吸附过程,该吸附过程属于单分子层化学吸附。在pH=6,温度为25℃,吸附时间为900 min,Pb(Ⅱ)初始浓度为30~900 mg/L的最佳条件下,RMSA对Pb(Ⅱ)的最大理论吸附量为454.54 mg/g。RMSA在多元重金属体系吸附实验中对Pb(Ⅱ)的吸附更具选择性。分析表明,离子交换是RMSA吸附Pb(Ⅱ)的主要机理。此外,RMSA经过5次循环实验仍能保持较高的吸附性能,在经济适用性方面具有较好的应用前景。

Red mud-sodium alginate hydrogel(RMSA)was prepared by cross-linking reaction using red mud and sodium alginate as raw materials.The effects of initial pH of solution,adsorption temperature,adsorption time,initial concentration and multiple heavy metal systems on the adsorption effect of RMSA on Pb(Ⅱ)were investigated by batch experiments and combined with XRD,FTIR and SEM-EDS characterization analysis,its adsorption characteristics on Pb(Ⅱ)was studied.The experimental results showed that the proposed secondary kinetic adsorption model and Langmuir adsorption isotherm model could better describe the adsorption process of RMSA on Pb(Ⅱ),which belonged to single molecular layer chemisorption.The maximum theoretical adsorption capacity of RMSA on Pb(Ⅱ)was 454.54 mg/g under the optimal conditions of pH=6,temperature of 25℃,adsorption time of 900 min and initial concentration of Pb(Ⅱ)of 30-900 mg/L.The adsorption of RMSA on Pb(Ⅱ)was more selective in the adsorption experiments of multivariate heavy metal systems.The analysis showed that ion exchange was the main mechanism of Pb(Ⅱ)adsorption by RMSA.In addition,RMSA still maintained high adsorption performance in the five-cycle experiment,which had a good application prospect in terms of economic applicability.