Zhang Wei, Hu Lishuang, Hu Shuangqi, Liu Yang
School of Environmental and Safety Engineering, North University of China 030051 Taiyuan China
RSC Adv. 2019 May 22;9(28):16058-16068. doi: 10.1039/c9ra00227h. eCollection 2019 May 20.
Metal ions in wastewater endanger the environment and even human life. In this study, an optimized method was used to synthesize an excellent hydrogel to treat these metal ions. The samples were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA), and applied to treat the Cu(ii) and Co(ii) ions in wastewater. In the adsorption experiment, the influential factors such as pH, adsorption time, adsorbent dosage and concentration of heavy metal ions and regeneration efficiency were evaluated, and the adsorption kinetics, isotherms and thermodynamics were studied. The orthogonal optimization results show that the best condition for synthesis was when the degree of neutralization of acrylic acid () was 70%, the quantity of glucose () was 0.2 g, the quantity of chitosan () was 0.05 g, and the quantity of initiator () was 0.03 g. The influence of the four factors was in the order > > > . The adsorption performance was optimal under neutral conditions and the dosage of 0.02 g adsorbent was chosen as the best. Experiments show that the composite hydrogels exhibited excellent performance under optimal conditions: at 20 °C and pH = 7, the adsorption capacity of 100 mg L of Cu(ii) by 0.01 g hydrogel was 286 mg g. The adsorption process of heavy metal ions by hydrogels conforms to pseudo-second-order kinetics and Langmuir isotherm model, which indicate a spontaneous endothermic reaction. Moreover, after five cycles, the removal rates of Cu(ii) and Co(ii) were 81% and 74.8%, respectively.
废水中的金属离子会危害环境甚至人类生命。在本研究中，采用了一种优化方法来合成一种优良的水凝胶以处理这些金属离子。通过傅里叶变换红外光谱（FTIR）、扫描电子显微镜（SEM）和热重分析（TGA）对样品进行了表征，并将其应用于处理废水中的Cu（II）和Co（II）离子。在吸附实验中，评估了pH值、吸附时间、吸附剂用量、重金属离子浓度和再生效率等影响因素，并研究了吸附动力学、等温线和热力学。正交优化结果表明，合成的最佳条件为丙烯酸（）的中和度为70%、葡萄糖（）的用量为0.2 g、壳聚糖（）的用量为0.05 g、引发剂（）的用量为0.03 g。这四个因素的影响顺序为 > > > 。在中性条件下吸附性能最佳，选择0.02 g吸附剂用量为最佳。实验表明，复合水凝胶在最佳条件下表现出优异的性能：在20℃和pH = 7时，0.01 g水凝胶对100 mg L的Cu（II）的吸附容量为286 mg g。水凝胶对重金属离子的吸附过程符合准二级动力学和朗缪尔等温线模型，表明这是一个自发的吸热反应。此外，经过五个循环后，Cu（II）和Co（II）的去除率分别为81%和74.8%。
