Department of Environmental Engineering, College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China E-mail:
Department of Civil, Environmental, and Construction Engineering, Texas Tech University, Lubbock, Texas 79409, USA.
Water Sci Technol. 2022 Sep;86(5):878-893. doi: 10.2166/wst.2022.258.
The lack of knowledge regarding competitive adsorption of heavy metal ions onto water treatment residuals has been hindering their reuse as a medium in stormwater bioretention systems. Competitive adsorption of copper(II), lead(II), cadmium(II), and zinc(II) onto polyaluminium chloride and anionic polyacrylamide water treatment residuals (PAC-APAM WTRs) was evaluated with different pH, temperature, initial concentration, and time. The competitive adsorption removal increased with the increase of pH and temperature. The analysis of the ratios of maximum adsorption capacity of a heavy metal ionic species in a multi-component system to that in a mono-component system (Q/Q) demonstrated that the coexisting ion had a negative effect on the adsorption of a metal ionic species. The Langmuir model provided a better fit, indicating that the adsorption could be a monolayer adsorption process. The modified Langmuir isotherm studies showed that the affinity order in the multi-component systems was Cu>Pb>Cd>Zn. The pseudo-second-order model better described the adsorption kinetics implying that the competitive adsorption behavior could be interpreted by diffusion-based mechanisms. This study contributed to a better understanding the mobility of those frequently occurring heavy metal ions in stormwater runoff in the PAC-APAM WTRs media layer of stormwater bioretention systems.
由于缺乏有关重金属离子在水处理残余物上竞争吸附的知识，阻碍了它们作为雨水生物滞留系统中介质的再利用。本文采用不同的 pH 值、温度、初始浓度和时间，评估了铜（II）、铅（II）、镉（II）和锌（II）在聚合氯化铝（PAC）和阴离子聚丙烯酰胺水处理残余物（APAM WTRs）上的竞争吸附。竞争吸附去除率随 pH 值和温度的升高而增加。对重金属离子在多组分体系中的最大吸附容量与单组分体系中的最大吸附容量之比（Q/Q）的分析表明，共存离子对金属离子的吸附有负面影响。Langmuir 模型提供了更好的拟合度，表明吸附是一个单层吸附过程。对改进的 Langmuir 等温线研究表明，多组分体系中的亲和顺序为 Cu>Pb>Cd>Zn。准二级动力学模型更好地描述了吸附动力学，表明竞争吸附行为可以通过基于扩散的机制来解释。本研究有助于更好地了解在雨水生物滞留系统中 PAC-APAM WTRs 介质层中，这些常见重金属离子在雨水径流水体中的迁移性。
