α-二氧化锰对钾离子吸附性能的研究及计算

Study on adsorption behavior and molecular simulation of α-MnO_2 for K^+

采用水热合成法,在一定温度、水热时间、酸浓度和物料物质的量比下,制得二氧化锰,同时对溶液中的钾离子进行吸附。对α-二氧化锰原样、改性及吸附后的样品进行XRD、SEM、FT-IR及XPS表征。应用Material Studio软件对吸附过程进行了分子模拟理论研究。结果显示,最佳合成条件为:晶化时间为12 h、n(硫酸锰)∶n(高锰酸钾)为3、温度为110℃、酸浓度为1.5 mol/L。在此条件下得到α-二氧化锰纳米棒,对钾离子吸附量最高为236.3 mg/g。经过5次吸脱附循环,所选样品对钾离子的吸附量由214.48 mg/g降至181.75 mg/g。经分子模拟计算,得到α-二氧化锰晶胞框架中钾离子的吸附位,吸附过程为放热反应,最大理论吸附量为299.62 mg/g,说明钾离子吸附容量仍有提升的空间。

α-MnO2 nanorod cluster was prepared by hydrothermal method under certain conditions,and modified to adsorb K^+from solution.All samples were characterized by XRD,SEM,FT-IR and XPS.The molecular simulation theory in the adsorption process was also studied by Material Studio software.The results showed thatα-MnO2 nanorods were obtained under temperature of 120℃,reaction time of 12 h,the amount-of-substance ratio of MnSO4 to KMnO4 of 3 and acid concentration of 1.5 mol/L.The maximum adsorptive capability of samples to K^+in solution was 236.3 mg/g.Absorbance of the sample decreased creased from 214.48 mg/g to 181.75 mg/g after five times of adsorption and desorption.Through molecular simulation calculation,K^+adsorptive sites inα-MnO2 framework were gained,maximum theoretical adsorptive capability was 299.62 mg/g and absorption process was exothermic.Thus proved the K^+adsorption still has some room to be improved.