芦苇半纤维素基水凝胶的制备及对重金属离子的高效吸附

Preparation of Reed Hemicelluloses-based Hydrogels and its Highly Effective Adsorption of Heavy Metal Ions

以芦苇半纤维素为基材,丙烯酸(AA)为单体,N,N,N',N'-四亚甲基乙二胺(MBA)为交联剂,通过自由基聚合法制备出水凝胶材料,采用FT-IR对其结构进行表征,并考察了AA和+MBA用量、pH值、吸附时间和金属离子初始质量浓度对水凝胶吸附Pd2、Cd2+和Zn2+性能的影响,同时探讨了水凝胶对金属离子的吸附动力学和吸附机制。结果表明,AA用量、MBA用量和pH值对水凝胶的吸附性能均有较大影响,水凝胶对金属离子的吸附量随着pH值的增加而增大,1.0 g半纤维素中添加0.1 g MBA,9 g AA制得的水凝胶可在60 min内达到吸附平衡,金属离子溶液初始质量浓度为200 mg/L,Pb2+溶液pH值5.5,Cd2+、Zn2+溶液pH值6.5时,对Pd2+、Cd2+和Zn2+的最大吸附量可达699、521和265 mg/g。水凝胶吸附金属离子过程属于离子交换机制,吸附行为符合动力学准二级模型和Langmuir方程,该水凝胶经过吸附-解吸8次循环后,对金属离子仍有较高的吸附效率,Pd2+、Cd2+和Zn2+的吸附量仍达616、479和243 mg/g,回收率分别为96.7%、97.1%和97.6%。

Reed hemicelluloses-based hydrogel was prepared by free radical polymerization using acrylic acid （AA） as monomer and N, N, N＇, N＇-tetramethylene ethylene diamine（MBA） as crosslinking agent. The chemical structure was characterized by FT-IR and the adsorption of heavy metal ions （Pd^2＋ , Cd^2＋ , and Zn^2＋ ） was also investigated. The effects of AA and MBA dosages, pH value, contacting time, and initial concentration of metal ion on the adsorption capacity were studied. At the same time the adsorption kinetics and adsorption mechanism of metal ions were discussed. The results showed that the adsorption capacity was influenced by AA and MBA dosages and pH value, and increased with the increase of pH value. The adsorption equilibrium time was approximately 60 min when the hemieellulose was 1.0 g, MBA was 0.1 g, and AA was 9 g. The maximum adsorption capacities of Pd^2＋ , Cd^2＋ , and Zn^2＋ were 699, 521, and 265 mg/g, respectively. The adsorption process was an ion- exchange mechanism. This suggested that the adsorption kinetics fitted the pseudo-second-order model and the adsorption followed the Langmuir model. Furthermore, reed hemicelluloses-based hydrogel also exhibited highly efficient adsorption of metal ions after 8 repeated adsorption/desorption cycles as the adsorption capacity of Pd^2＋ , Cd^2＋ , and Zn^2＋ were 616, 479 and 243 mg/g, and the recovery of Pd^2＋ , Cd^2＋ , and Zn^2＋ were 96.7%, 97.1% and 97.6% , respectively.