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离子液体改性壳聚糖复合沸石吸附材料的制备及对Pb(Ⅱ)、Cu(Ⅱ)的吸附研究
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摘要
壳聚糖富含氨基和羟基官能团,易与重金属离子螯合。但其密度小,沉降速度慢难以实施对重金属离子的高效吸附。利用谷氨酸基离子液体,改性壳聚糖,提高其溶解性,并通过复合沸石,得到新型壳聚糖—沸石吸附材料。通过静态试验,研究了壳聚糖—沸石吸附材料对Pb~(2+)、Cu~(2+)的吸附,并通过与未改性沸石对比,分析了吸附剂剂量、pH值、比表面积等因素对吸附过程的影响,结果显示:两种金属离子的去除率均可达到98%,改性壳聚糖—沸石吸附材料的比表面积比未改性沸石提高了近三倍。利用FTIR和SEM、EDS能谱分析比较改性前后吸附剂的表面形貌、官能团和元素组成变化情况,结果表明:改性后的吸附材料,具有更多的活性位点,表面内孔结构有显著的变化,微观结构证明了其吸附性能的改进得益于其表面结构的改变。吸附等温线模型研究分析其对Pb~(2+)、Cu~(2+)的吸附复合Langmuir吸附等温模型,证明其吸附行为属于单层吸附;动力学研究证明其符合假二级动力学吸附,说明其吸附过程是化学吸附。
Chitosan is a rich source of amino and hydroxyl groups,easy chelation with heavy metal ions.Use of glutamic acid ionic liquids,chitosan was modified and composed zeolite,get new Chitosan-Zeolite adsorbent.Through static test,studying adsorption of Pb2 +,Cu2 + with the new adsorbent.The results show that the removal ratio of the two ions is nearly 98%,the specific surface area of modified chitosan-zeolite adsorbent is nearly three times higher than that of unmodified zeolite,Using FTIR and SEM,EDS analysis the modification of adsorbent surface topography,the results show that the modified adsorbent,has a more active site,the surface of the inner hole structure have obvious changes.The adsorption of Pb2 +,Cu2 + is fit for Langmuir adsorption isotherm,prove its belongs to monolayer adsorption;Kinetic studying proves its accord with Pseudo-secondary dynamic model,suggests that the process is a chemical adsorption.
引文
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