Department of Civil Engineering, Shahrood University of Technology, Shahrood, Iran E-mail:
Water Sci Technol. 2020 Dec;82(11):2603-2612. doi: 10.2166/wst.2020.499.
In this study, adsorption/desorption of vancomycin (VAN) on bentonite nanoparticles was investigated in a batch system. Adsorption experiments were carried out as a function of several influential parameters such as adsorbent dosage, pH, contact time and ionic strength. Bentonite nanoparticles were characterized by field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer-Emmett-Teller, and Fourier transform infrared (FTIR) analyses and the mesoporous structure was revealed. Langmuir, Freundlich, and Temkin isotherm models were applied for the examination of equilibrium data, and Langmuir was found to be the best fit. With the increase in pH and ionic strength, the adsorption capacity decreases, which suggests the adsorption process may be dominated by the cation exchange mechanism. Moreover, VAN desorption from bentonite nanoparticles in two initial VAN loadings was investigated under different concentrations of metallic cations of various valences (Na, Ca, Al), and pHs 3-10. Desorption was strongly pH-dependent and the amount of VAN desorbed increased with increasing cations concentrations. The FTIR analysis before and after VAN desorption suggests that the formation of Al-VAN and Ca-VAN complexes on the solid surface and then their detachment from the solid surface may contribute to the higher VAN desorption by Al and Ca.
在这项研究中，采用批处理系统研究了万古霉素（VAN）在膨润土纳米颗粒上的吸附/解吸。进行了吸附实验，考察了几个影响因素，如吸附剂用量、pH 值、接触时间和离子强度。通过场发射扫描电子显微镜、能量色散 X 射线光谱、Brunauer-Emmett-Teller 和傅里叶变换红外（FTIR）分析对膨润土纳米颗粒进行了表征，揭示了其介孔结构。应用 Langmuir、Freundlich 和 Temkin 等温模型对平衡数据进行了检验，发现 Langmuir 模型拟合度最佳。随着 pH 值和离子强度的增加，吸附容量降低，这表明吸附过程可能主要受阳离子交换机制的控制。此外，还研究了在不同价态（Na、Ca、Al）的金属阳离子浓度和 pH 值 3-10 条件下，从两种初始 VAN 负载量的膨润土纳米颗粒中解吸 VAN。解吸强烈依赖于 pH 值，解吸的 VAN 量随着阳离子浓度的增加而增加。VAN 解吸前后的 FTIR 分析表明，在固-液界面上形成了 Al-VAN 和 Ca-VAN 复合物，然后这些复合物从固-液界面上脱附，这可能是 Al 和 Ca 导致 VAN 解吸率较高的原因。
