State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093, PR China.
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093, PR China.
J Colloid Interface Sci. 2012 Jan 15;366(1):37-43. doi: 10.1016/j.jcis.2011.09.070. Epub 2011 Oct 2.
Iron oxides tend to be immobilized within nanoporous supports to improve their feasibility for practical environmental remediation including arsenic and heavy metal removal. Contrary to the co-ions, little is known concerning the effect of counter ions on the performance of the resultant composites. In this study, two hybrid sorbents (denoted as HFO-PS(-) and HFO-PS(0), respectively) were prepared by loading hydrous ferric oxide (HFO) nanoparticles onto two polystyrene beads: PS(-), negatively charged with sulfonic acid groups, and PS(0), covalently bonded with neutral chloromethyl groups. Effects of sulfate on their sorption toward Cu ions were investigated. Consistent with the case in bulky HFO particles, the amount of Cu adsorbed on HFO-PS(0) was markedly promoted by introducing sulfate. As for HFO-PS(-), with monovalent cation as background (Na(+)), it exhibited an apparent decrease in Cu sorption as a result of the competing effect of Na ions and the Cu-SO(4) complexation in solution. Contrarily, the adsorbed Cu was increased by introducing sulfate in the divalent cation background (Ca), because sulfate ions were allowed to access to the loaded HFO nanoparticles due to the screening of the sulfonic acid groups caused by Ca ions. XPS spectroscopy further demonstrated that besides the electrostatic effects, the formation of Cu-SO(4) ternary complexes also accounted for the enhanced Cu sorption on both bulky HFO and hybrid HFO sorbents in the presence of sulfate. These results indicated that the effect of counter-ion ligands on metal adsorption to hybrid iron oxides was largely dependent on the surface properties of the host materials.
氧化铁倾向于固定在纳米多孔载体中，以提高其在实际环境修复中的可行性，包括砷和重金属的去除。与共离子相反，关于反离子对所得复合材料性能的影响知之甚少。在这项研究中，通过将水合氧化铁（HFO）纳米颗粒负载到两种聚苯乙烯珠上，制备了两种混合吸附剂（分别表示为 HFO-PS(-)和 HFO-PS(0)）：PS(-)，带负电荷磺酸基团，PS(0)，与中性氯甲基基团共价键合。研究了硫酸盐对它们吸附 Cu 离子的影响。与大块 HFO 颗粒的情况一致，引入硫酸盐显著促进了 HFO-PS(0)上 Cu 的吸附量。对于 HFO-PS(-)，在单价阳离子背景（Na(+)）下，由于溶液中 Na 离子的竞争效应和 Cu-SO(4)络合作用，Cu 吸附明显减少。相反，在二价阳离子背景（Ca）中引入硫酸盐会增加吸附的 Cu，因为 Ca 离子引起的磺酸基团屏蔽作用允许硫酸盐离子进入负载的 HFO 纳米颗粒。XPS 光谱学进一步表明，除了静电效应外，Cu-SO(4)三元配合物的形成也解释了在硫酸盐存在下，大块 HFO 和混合 HFO 吸附剂上 Cu 吸附增强的原因。这些结果表明，反离子配体对混合氧化铁中金属吸附的影响在很大程度上取决于宿主材料的表面性质。
