Department of Civil and Environmental Engineering, University of Wisconsin - Milwaukee, Milwaukee, WI, 53201, USA.
Department of Civil and Environmental Engineering, University of Wisconsin - Milwaukee, Milwaukee, WI, 53201, USA.
Environ Res. 2021 Mar;194:110685. doi: 10.1016/j.envres.2020.110685. Epub 2021 Jan 8.
Excessive amount of phosphate entering water bodies may cause eutrophication and have detrimental effects on ecosystems. Clay-based materials have been drawing attractive attention in mitigating phosphate release to aquatic environment. In this study, we prepared a series of zirconium (Zr)-modified clays to investigate the effect of clay structure and expansion property on phosphate adsorption. Kaolinite, montmorillonite, and vermiculite were selected as three representative natural clays for Zr modification, and the resulting Zr-modified clays were characterized using various techniques that included powder X-ray diffraction, scanning electron microscopy, and zeta potential measurement. Different Zr-modified clays exhibited substantially different phosphate adsorption behaviors, which may be related to the distinct structural and expansion properties of each clay substrate. Particularly, Zr-modified montmorillonite had fastest phosphate adsorption kinetics and highest phosphate adsorption capacity among all Zr-modified clays, which may be attributed to the good expansion property of montmorillonite that favored the uniform intercalation of Zr species, making the adsorption sites easily accessible by phosphate. Furthermore, all Zr-modified clays showed robust performance for phosphate adsorption under various water chemistry conditions. Combined aqueous sorption and solid characterization analyses suggested that formation of inner-sphere surface complexes may be the primary mechanism for phosphate adsorption by Zr-modified clays.
过量的磷酸盐进入水体可能导致富营养化，并对生态系统产生有害影响。基于粘土的材料在减轻磷酸盐向水生环境释放方面引起了人们的极大关注。在这项研究中，我们制备了一系列锆（Zr）改性粘土，以研究粘土结构和膨胀性能对磷酸盐吸附的影响。选择高岭石、蒙脱石和蛭石作为三种代表性的天然粘土进行 Zr 改性，并用粉末 X 射线衍射、扫描电子显微镜和动电位测量等多种技术对所得 Zr 改性粘土进行了表征。不同的 Zr 改性粘土表现出明显不同的磷酸盐吸附行为，这可能与每种粘土基质的独特结构和膨胀性能有关。特别是，Zr 改性蒙脱石在所有 Zr 改性粘土中表现出最快的磷酸盐吸附动力学和最高的磷酸盐吸附容量，这可能归因于蒙脱石良好的膨胀性能有利于 Zr 物种的均匀插层，使吸附位点易于被磷酸盐占据。此外，所有 Zr 改性粘土在各种水化学条件下都表现出对磷酸盐吸附的稳健性能。综合水相吸附和固体特性分析表明，内圈表面络合可能是 Zr 改性粘土吸附磷酸盐的主要机制。
