Zhao Chao-Ran, Shan Hui-Mei, Zeng Chun-Ya, Zhang Jin-Xian, Peng San-Xi
Guangxi Key Laboratory of Environmental Pollution Control Theory and Technology, College of Environmental Science and Engineering, Guilin University of Technology, Guilin 541006, China.
College of Earth Science, Guilin University of Technology, Guilin 541006, China.
Huan Jing Ke Xue. 2020 Aug 8;41(8):3665-3674. doi: 10.13227/j.hjkx.202001183.
Based on the principle of self-assembly, graphene oxide, chitosan, and FeCl·6HO were mixed to prepare graphene oxide-chitosan coated iron-composite particles (Fe@ GOCS). Batch static experiments were carried out to investigate the kinetic and thermodynamic characteristics of As(Ⅲ) adsorption, and to identify the adsorption mechanism. Results showed that the iron on the GOCS was mainly in the form of -FeO(OH). The As(Ⅲ) adsorption capacity increased with decreasing pH, and the highest adsorption capacity occurred at pH 3. After approximately 45 h, As(Ⅲ) adsorption reached equilibrium under the conditions of pH 3 and a temperature of 298.15, 308.15, and 318.15 K. The maximum adsorption capacity was 289.4 mg·g for an optimal dosage of adsorbents of 1.0 g·L. After five times of repeated adsorption-desorption, the adsorption capacity increased slightly. The thermodynamic parameters showed that Δ<0, Δ > 0, and Δ>0, thus indicating that As(Ⅲ) adsorption on Fe@GOCS was a spontaneous, endothermic, and entropy-increasing reaction, and that a higher temperature was more favorable for As(Ⅲ) adsorption. The pseudo-second-order model provided a good fit of the As(Ⅲ) adsorption kinetics for Fe@GOCS. Compared to the Langmuir isotherm, As(Ⅲ) adsorption experimental data fitted better to the Freundlich and Sips models. In combination with the characterization results, it was found that ion exchange and surface complexation were the main mechanisms of As(Ⅲ) removal from aqueous solution using Fe@GOCS.
基于自组装原理，将氧化石墨烯、壳聚糖和FeCl₃·6H₂O混合制备氧化石墨烯-壳聚糖包覆铁复合颗粒（Fe@GOCS）。进行批量静态实验以研究As(Ⅲ)吸附的动力学和热力学特性，并确定吸附机制。结果表明，GOCS上的铁主要以FeO(OH)的形式存在。As(Ⅲ)的吸附容量随pH值降低而增加，在pH 3时吸附容量最高。在pH 3、温度为298.15、308.15和318.15 K的条件下，大约45小时后As(Ⅲ)吸附达到平衡。吸附剂最佳投加量为1.0 g·L时，最大吸附容量为289.4 mg·g⁻¹。经过五次重复吸附-解吸后，吸附容量略有增加。热力学参数表明，ΔG<0、ΔH>0、ΔS>0，因此表明As(Ⅲ)在Fe@GOCS上的吸附是一个自发、吸热且熵增加的反应，较高温度更有利于As(Ⅲ)的吸附。准二级模型能很好地拟合Fe@GOCS对As(Ⅲ)的吸附动力学。与Langmuir等温线相比，As(Ⅲ)吸附实验数据更符合Freundlich和Sips模型。结合表征结果发现，离子交换和表面络合是Fe@GOCS去除水溶液中As(Ⅲ)的主要机制。
