含氮大分子吸附剂的制备及其对Cd(Ⅱ)的吸附

Preparation of nitrogen-containing macromolecular adsorbent and its adsorption for Cd(Ⅱ)

利用三聚氯氰的温度梯度反应活性,在较低温度下,用多乙烯多胺与三聚氯氰进行亲核取代反应,合成出一种以三嗪环为连接点的不溶含氮大分子颗粒吸附剂(N-MGA),并将其用于去除水体中的Cd(Ⅱ)。通过元素分析、FTIR和SEM对N-MGA进行表征,同时对Cd(Ⅱ)的吸附进行吸附动力学、等温吸附模型拟合和吸附机理进行研究,考察了溶液pH对Cd(Ⅱ)吸附性能的影响、吸附剂的吸附-解吸再生循环性能及结构稳定性。结果表明,该吸附剂对Cd(Ⅱ)的吸附机理是利用吸附剂氨基上氮的孤对电子与Cd(Ⅱ)的配位络合作用进行吸附,且吸附过程符合准二级动力学模型和Langmuir吸附等温线模型,最大吸附量可达539.1 mg/g,且对Cd(Ⅱ)的吸附较为容易,吸附能力较强;在Cd(Ⅱ)初始质量浓度为3636.5和70.0 mg/L时,对Cd(Ⅱ)的吸附率分别可达97.5%和99.9%,且10次吸附-解吸再生循环中吸附率维持在97.0%~98.2%,解吸率均在97.6%以上,吸附剂回收率均在92.0%以上。

Water-insoluble nitrogen-containing macromolecular granular adsorbent(N-MGA) was synthesized at low temperature though nucleophilic substitution between polyethylene polyamine and cyanuric chloride due to the temperature gradient reaction activity of cyanuric chloride and used to treat Cd(Ⅱ) in water, herein, the triazine ring of cyanuric chloride served as connection point to combine polyethylene polyamine and cyanuric chloride. The synthesized particulate adsorbent was characterized by elemental analysis, FTIR and SEM. At the same time, the adsorption kinetics, isothermal adsorption model fitting and adsorption mechanism of Cd(Ⅱ) were studied. The effect of pH of solution on the adsorption performance of Cd(Ⅱ) was investigated. The performance and structural stability of the adsorbent after adsorption-desorption regeneration were also investigated. The results showed that the adsorption mechanism of the adsorbent for Cd(Ⅱ) was the coordination complexation between the lone pair electrons of nitrogen on the amine group on the surface of the adsorbent and Cd(Ⅱ), and the adsorption process was in line with the pseudo-second-order kinetic model and the Langmuir adsorption model. The maximum adsorption capacity reached 539.1 mg/g, and the adsorption of Cd(Ⅱ) was relatively easy and strong. When the initial mass concentrations of Cd(Ⅱ) were 3636.5 and 70.0 mg/L, and the adsorption rates of Cd(Ⅱ) were 97.5% and 99.9%, respectively. During the 10 adsorption-desorption regeneration cycles, the adsorption rate was maintained about 97.0%~98.2%, the desorption rate was above 97.6%, and the recovery rate of the adsorbent was above 92.0%.