Xue Xiang-Dong, Yang Chen-Hao, Yu Jian-Lin, Zhuang Hai-Feng, Fang Chen-Ran
School of Civil Engineering and Architectural, Zhejiang University of Science and Technology, Hangzhou 310023, China.
College of Civil Engineering, Zhejiang University of Technology, Hangzhou 310023, China.
Huan Jing Ke Xue. 2021 Jun 8;42(6):2856-2867. doi: 10.13227/j.hjkx.202010152.
To clarify the interactions between heavy metals, antibiotics, and humic acid, copper (Cu), oxytetracycline (OTC), norfloxacin (NOR), and humic acid samples from river sediment in the Polder area were selected to build single and coexisting systems. Groups of experiments were designed to investigate the kinetics, thermodynamics, and isotherms of Cu, OTC, and NOR adsorption onto humic acid in single and Cu+OTC and Cu+NOR coexisting systems (concentration ratio=1:1). The physicochemical properties of humic acid were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), BET tests, and IR spectroscopy, and the possible adsorption mechanisms are discussed. The results showed that the humic acid was a typical amorphous material with a negative charge and non-uniform porous structure, and the pore size was at the mesoporous scale. In the single systems, the saturated adsorption capacity () of Cu, OTC, and NOR onto humic acid was 33.043, 19.512, and 26.676 mg·g, respectively. In the Cu+OTC system, the of Cu and OTC was 38.053 and 25.965 mg·g, respectively. In the Cu+NOR system, the of Cu and NOR was 39.187 and 32.728 mg·g, respectively. The adsorption behaviors in the single and coexisting systems were similar and the adsorption processes were well fitted by the pseudo-second-order kinetic equation; the Sips model provided good descriptions for the isothermal adsorption equilibrium. Moreover, adsorption thermodynamics were characterized by spontaneous endothermic reactions with the reduction of free energy and the increase of enthalpy and entropy. It can be concluded that Cu combines with OTC and NOR to form complexes, which increases the number of species available for adsorption by humic acid. Also, adsorbed Cu can combine with free OTC and NOR in a bridging manner. Thus, a more favorable adsorption situation occurred in the coexisting systems. The IR characteristics of the carboxyl, phenolic hydroxyl, ketone, and aldehyde groups of humic acid changed by different degrees after adsorption, indicating that oxygen-containing functional groups generally participated in the adsorption reactions.
为阐明重金属、抗生素和腐殖酸之间的相互作用，选取了圩区河流沉积物中的铜（Cu）、土霉素（OTC）、诺氟沙星（NOR）和腐殖酸样品来构建单一体系和共存体系。设计了多组实验来研究在单一体系以及Cu+OTC和Cu+NOR共存体系（浓度比=1:1）中，Cu、OTC和NOR在腐殖酸上吸附的动力学、热力学和等温线。通过扫描电子显微镜（SEM）、X射线衍射（XRD）、BET测试和红外光谱对腐殖酸的物理化学性质进行了分析，并探讨了可能的吸附机制。结果表明，腐殖酸是一种典型的无定形材料，带负电荷且具有不均匀的多孔结构，孔径处于中孔尺度。在单一体系中，Cu、OTC和NOR在腐殖酸上的饱和吸附量（）分别为33.043、19.512和26.676 mg·g。在Cu+OTC体系中，Cu和OTC的分别为38.053和25.965 mg·g。在Cu+NOR体系中，Cu和NOR的分别为39.187和32.728 mg·g。单一体系和共存体系中的吸附行为相似，吸附过程能很好地用准二级动力学方程拟合；Sips模型对等温吸附平衡有很好的描述。此外，吸附热力学的特征是自发的吸热反应，伴随着自由能的降低以及焓和熵的增加。可以得出结论，Cu与OTC和NOR结合形成络合物，这增加了可被腐殖酸吸附的物种数量。而且，吸附的Cu可以以桥联方式与游离的OTC和NOR结合。因此，在共存体系中出现了更有利的吸附情况。腐殖酸的羧基、酚羟基、酮基和醛基的红外特征在吸附后有不同程度的变化，表明含氧基官能团普遍参与了吸附反应。
