Cheng Dengmiao, Chen Jianyu, Wang Jing, Liu Xinhui
Research Center for Eco-Environmental Engineering, Dongguan University of Technology, Dongguan, 523808, PR China.
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, PR China.
Heliyon. 2023 May 1;9(5):e15979. doi: 10.1016/j.heliyon.2023.e15979. eCollection 2023 May.
Particles are ubiquitous and abundant in natural waters and play a crucial role in the fate and bioavailability of organic pollution. In the present study, natural mineral (kaolinites, KL), organic (humic/fulvic acid, HA/FA) and their composite particles were further separated into particles fractions (PFs, >1 μm) and colloidal fractions (CFs, 1 kDa-1 μm) by cross-flow ultrafiltration (CFUF). This research demonstrated the role of kaolinite-humic composite colloids on the adsorption of fluoroquinolone norfloxacin (NOR). The Freundlich model satisfactory described adsorption curves, showing strong affinity of NOR to CFs, with sorption capacity () between 8975.50 and 16638.13 for NOR. The adsorption capacities of NOR decreased with the particle size increasing from CFs to PFs. In addition, composite CFs showed excellent adsorption capacity, which was mainly attributed to the larger specific surface area of composite CFs and electronegativity and numerous oxygen-containing functional groups on the surfaces of the complexes, and electrostatic attraction, hydrogen bond and cation exchange could dominate the NOR adsorption onto the composite CFs. The best pH value under adsorption condition of composite CFs varied from weakly acidic to neutral with the increase of load amount of humic and fulvic acids on the surface of inorganic particles. The adsorption decreased with higher cation strength, larger cation radius and higher cation valence, which depended on the surface charge of colloids and the molecular shape of NOR. These results provided insight into the interfacial behaviors of NOR on the surfaces of natural colloids and promoted the understanding of the migration and transport of antibiotics in environmental systems.
颗粒在天然水体中无处不在且含量丰富，在有机污染物的归宿和生物可利用性方面发挥着关键作用。在本研究中，通过错流超滤（CFUF）将天然矿物（高岭土，KL）、有机物（腐殖酸/富里酸，HA/FA）及其复合颗粒进一步分离为颗粒级分（PFs，>1μm）和胶体级分（CFs，1kDa - 1μm）。本研究证明了高岭土 - 腐殖质复合胶体对氟喹诺酮类诺氟沙星（NOR）吸附的作用。Freundlich模型很好地描述了吸附曲线，表明NOR对CFs具有很强的亲和力，NOR的吸附容量（）在8975.50至16638.13之间。随着粒径从CFs增加到PFs，NOR的吸附容量降低。此外，复合CFs表现出优异的吸附容量，这主要归因于复合CFs较大的比表面积、电负性以及络合物表面大量的含氧官能团，静电吸引、氢键和阳离子交换主导了NOR在复合CFs上的吸附。随着无机颗粒表面腐殖酸和富里酸负载量的增加，复合CFs吸附条件下的最佳pH值从弱酸性变化到中性。随着阳离子强度增加、阳离子半径增大和阳离子价态升高，吸附降低，这取决于胶体的表面电荷和NOR的分子形状。这些结果深入了解了NOR在天然胶体表面的界面行为，并促进了对环境系统中抗生素迁移和运输的理解。
