Chen Weiming, Shen Yi, Ling Ying, Peng Yaotian, Ge Moyan, Pan Ziyan
School of Food Science and Engineering and School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China.
ACS Omega. 2019 Apr 11;4(4):6669-6676. doi: 10.1021/acsomega.9b00318. eCollection 2019 Apr 30.
Uniform positively charged polystyrene microspheres were synthesized and further examined as a new sorbent for water remediation. The structures of the resulting sorbent were characterized by field-emission scanning electron microscopy, Fourier transform infrared spectroscopy, and H nuclear magnetic resonance spectroscopy. The adsorption performance of the sorbent was evaluated using three typical pollutants, namely, Congo red, phosphate, and Cr(VI). The adsorption isotherms were fitted by the Langmuir and Freundlich models, while the adsorption kinetics was analyzed by the pseudo-first-order, pseudo-second-order, and intraparticle diffusion equations. The thermodynamic parameters of the adsorption process including changes of enthalpy, entropy and Gibbs free energy, and binding constant were obtained by isothermal titration calorimetry measurements. The effects of solution pH and competitive ions on the adsorption process were investigated. The adsorption isotherms could be better fitted by the Langmuir model, yielding maximum adsorption capacities of 18, 6.2, and 1.1 mg g for the adsorption of Congo red, Cr(VI), and phosphate, respectively. The adsorption kinetics could be best described by the pseudo-second-order equation. The spent sorbent was regenerated by washing with 1 M KOH and showed outstanding long-term cyclic performance. The findings suggested that the positive charges at the surface of polystyrene microspheres could serve as effective sites for the immobilization of anionic pollutants in solutions owing to the electrostatic attraction.
合成了均匀带正电的聚苯乙烯微球，并将其作为一种新型的水修复吸附剂进行了进一步研究。通过场发射扫描电子显微镜、傅里叶变换红外光谱和氢核磁共振光谱对所得吸附剂的结构进行了表征。使用三种典型污染物，即刚果红、磷酸盐和六价铬，评估了吸附剂的吸附性能。吸附等温线用朗缪尔和弗伦德里希模型拟合，吸附动力学用准一级、准二级和颗粒内扩散方程进行分析。通过等温滴定量热法测量获得了吸附过程的热力学参数，包括焓变、熵变和吉布斯自由能变化以及结合常数。研究了溶液pH值和竞争离子对吸附过程的影响。吸附等温线用朗缪尔模型拟合效果更好，刚果红、六价铬和磷酸盐吸附的最大吸附容量分别为18、6.2和1.1 mg/g。吸附动力学用准二级方程描述效果最佳。用过的吸附剂用1 M KOH洗涤进行再生，并表现出出色的长期循环性能。研究结果表明，由于静电吸引，聚苯乙烯微球表面的正电荷可作为溶液中阴离子污染物固定的有效位点。
