Wallace Anna Rose, Su Chunming, Sun Wenjie
Department of Civil and Environmental Engineering, Southern Methodist University, Dallas, Texas.
Groundwater, Watershed, and Ecosystem Restoration Division, National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Ada, Oklahoma.
Environ Eng Sci. 2019 May 9;36(5):634-642. doi: 10.1089/ees.2018.0438.
This study investigated the adsorptive removal of fluoride from simulated water pollution using various (hydro)oxide nanomaterials, which have the potential to be used as sorbents for surface water and groundwater remediation. Tested nanomaterials include hematite, magnetite, ferrihydrite, goethite, hematite-alpha, hydroxyapatite (HAP), brucite, and four titanium dioxides (TiO-A [anatase], TiO-B [rutile], TiO-C [rutile], and TiO-D [anatase]). Among 11 (hydro)oxide nanomaterials tested in this study, ferrihydrite, HAP, and brucite showed two to five times higher removal of fluoride than other nanomaterials from synthetic fluoride solutions. Freundlich and Redlich-Peterson adsorption isotherms better described the adsorptive capacity and mechanism than the Langmuir isotherm based on higher values, indicating better fit of the regression predictions. In addition, the adsorption kinetics were well described by the intraparticle diffusion model. Column studies in a fixed bed continuous flow through system were conducted to illustrate the adsorption and desorption behavior of fluoride on ferrihydrite, HAP, or brucite. Experimental results fitted well with the Thomas model because of the values at least 0.885 or higher. By comparisons of the adsorption capacity and the rate constant, columns packed with ferrihydrite exhibited not only faster rates but also higher sorption capacity than those packed with HAP or brucite. Desorption tests in deionized water showed that the adsorbed fluoride could be desorbed at a lower efficiency, ranging from 4.0% to 8.9%. The study implicated that (hydro)oxide nanomaterials of iron calcium and magnesium could be effective sorptive materials incorporated into filtration systems for the remediation of fluoride polluted water.
本研究调查了使用各种（氢）氧化物纳米材料从模拟水污染中吸附去除氟化物的情况，这些纳米材料有潜力用作地表水和地下水修复的吸附剂。测试的纳米材料包括赤铁矿、磁铁矿、水铁矿、针铁矿、α-赤铁矿、羟基磷灰石（HAP）、水镁石以及四种二氧化钛（TiO-A [锐钛矿型]、TiO-B [金红石型]、TiO-C [金红石型] 和 TiO-D [锐钛矿型]）。在本研究测试的11种（氢）氧化物纳米材料中，水铁矿、HAP和水镁石从合成氟化物溶液中去除氟化物的能力比其他纳米材料高出两到五倍。基于更高的 值，Freundlich和Redlich-Peterson吸附等温线比Langmuir等温线能更好地描述吸附容量和吸附机制，表明回归预测的拟合度更好。此外，颗粒内扩散模型很好地描述了吸附动力学。在固定床连续流系统中进行了柱实验，以说明氟化物在水铁矿、HAP或水镁石上的吸附和解吸行为。由于 值至少为0.885或更高，实验结果与Thomas模型拟合良好。通过比较吸附容量和速率常数，填充水铁矿的柱不仅速率更快，而且吸附容量比填充HAP或水镁石的柱更高。在去离子水中进行的解吸试验表明，吸附的氟化物解吸效率较低，范围为4.0%至8.9%。该研究表明，铁、钙和镁的（氢）氧化物纳米材料可以作为有效的吸附材料纳入过滤系统，用于修复氟污染水。
