Key Laboratory of Subsurface Hydrology and Ecology in Arid Areas, Ministry of Education, Chang'an University, Xi'an, 710054, China.
School of Water and Environment, Chang'an University, Xi'an, 710054, China.
Environ Sci Pollut Res Int. 2020 Jan;27(2):1697-1709. doi: 10.1007/s11356-019-06787-3. Epub 2019 Nov 21.
To reveal the adsorption mechanism of sediment to antibiotics with the presence of dissolved organic matter (DOM), batch experiments were carried out by oxytetracycline (OTC) on sediments with decayed plants (PDOM) and composted chicken manure (MDOM), and the zeta potential in the system before and after adsorption was measured. Results showed that the PDOM promoted the adsorption process, while the MDOM inhibited the adsorption. Adding PDOM, the change of zeta potential (Δζ) increased by 40.08% for first terrace sediments (FT) and 63.98% for riverbed sediments (RB), respectively; meanwhile, MDOM decreased by 20.04% for FT and 28.39% for RB, respectively. The results of kinetic fitting models of replacing the adsorption amount with Δζ were consistent with the initial. It indicated that there was a positive correlation between the adsorption amount and Δζ, and the zeta potential can be used to quickly judge the degree of adsorption process. The Derjaguin-Landau-Verwey-Overbeek (DLVO) theory describes the interactions of sediment particles. In terms of adsorption amount, zeta potential (absolute value) and total interaction energy all followed the order: RB > FT, RB-PDOM > FT-PDOM, and RB-MDOM > FT-MDOM. The more negative the zeta potential is, the better the dispersion of the particles is. Stronger repulsion is more conducive to adsorbing positively charged OTC. The site energy distribution theory further explained that the distribution of adsorption site in the various states of sediments increased while adding the PDOM and decreased while adding the MDOM.
为揭示有溶解有机质（DOM）存在时沉积物对抗生素的吸附机制，采用四环素（OTC）在腐殖植物沉积物（PDOM）和堆肥鸡粪沉积物（MDOM）上进行批实验，并测定了吸附前后体系的动电电位。结果表明，PDOM 促进了吸附过程，而 MDOM 抑制了吸附。添加 PDOM 后，一级阶地沉积物（FT）和河床沉积物（RB）的动电电位变化（Δζ）分别增加了 40.08%和 63.98%；而 MDOM 则分别降低了 20.04%和 28.39%。用Δζ 代替吸附量的动力学拟合模型的结果与初始值一致。这表明吸附量与Δζ 之间存在正相关关系，动电电位可用于快速判断吸附过程的程度。德热固兰海文奥韦尔贝克（DLVO）理论描述了沉积物颗粒之间的相互作用。就吸附量、动电电位（绝对值）和总相互作用能而言，均遵循 RB＞FT、RB-PDOM＞FT-PDOM 和 RB-MDOM＞FT-MDOM 的顺序。动电电位越负，颗粒的分散性越好。更强的排斥力更有利于吸附带正电荷的 OTC。吸附点位能分布理论进一步解释了随着 PDOM 的添加，沉积物各种状态下的吸附点位分布增加，而随着 MDOM 的添加则减少。
