The Wolfson Faculty of Chemical Engineering, Technion - Israel Institute of Technology, Technion City, Haifa 32000, Israel.
Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha, 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha, 410083, China.
J Hazard Mater. 2017 Sep 15;338:472-481. doi: 10.1016/j.jhazmat.2017.06.001. Epub 2017 Jun 3.
The inner structure of iron oxyhydroxide agglomerates (IOAs) prepared from hydrolysis of ferric chloride was characterized and correlated to surface complexation of hexavalent chromium, Cr(VI), in a broad range of pH (3-12) and ionic strengths (0.0-5.0M). Evolution of particle size, morphology, and surface activity, combined with density functional theory (DFT) calculations, support the condensation reaction initiated formation of IOAs in three levels: iron nanoparticles to nanolayers to agglomerates. This agglomeration process led to a layered porous structure for aqueous-phase IOAs resulting in a rapid and high removal of Cr(VI) in batch tests. By integrating adsorption results, thermodynamic modeling, and quantum chemical calculations for the adsorption reactions, a quantitative distribution profile for each surface coordination of Cr(VI) ions (i.e., monodentate, bidentate, and hydrogen-bonding) was established. Results of this study are important to understand the fundamental mechanism of IOAs formation in aqueous phase and the intrinsic nature of surface complexations at the mineral-water interface for optimal Cr(VI) removal in hypersaline waste streams.
从三价铁氯化物水解制备得到的氢氧化铁团聚体（IOA）的内部结构，在很宽的 pH 值（3-12）和离子强度（0.0-5.0M）范围内，与六价铬（Cr(VI)）的表面络合进行了特征分析和关联。颗粒尺寸、形态和表面活性的演变，结合密度泛函理论（DFT）计算，支持了在三个层次上引发 IOA 形成的缩合反应：铁纳米颗粒到纳米层到团聚体。这种团聚过程导致水相 IOA 形成层状多孔结构，从而在批量测试中实现了 Cr(VI)的快速和高效去除。通过整合吸附结果、热力学建模和吸附反应的量子化学计算，建立了 Cr(VI)离子的每个表面配位（即单齿、双齿和氢键）的定量分布曲线。这项研究的结果对于理解水相 IOA 形成的基本机制以及矿-水界面的表面络合内在性质，从而在高盐废水中实现最佳 Cr(VI)去除非常重要。
