静电强化去除水中低浓度锑的载铁复合吸附体系构建及除锑机制

The toxicity and health risk of antimony （Sb） to human is gradually clear, and the Sb pollution caused by anthropogenic activity becomes serious. However, the researches on the Sb removal, especially in trace concentration, are very limited. Iron oxide has been proven as an efficient adsorbent for Sb, but the actual removal rate is far from the expected because the Sb(V), except in the mining river, in several to tens of μg/L is difficult to transfer to the adsorptive site on the surface of iron oxide. The proposed study constructs a nano iron oxide supported composite adsorbent by using a positively charged polymer to provide the positive electric field, which can solve the slow mass transfer problem by enriching the Sb(V) in water to the adsorptive sites by the electrostatic effect. The study also regulates the pore structure, positive charge density and supported iron amount of the composite adsorbent, to analyze the relationship between the additional electrostatic field and the Sb(V) removal. Furthermore, it raises the charge amount by complexation of the polymer with transition metal cation to increase the electrostatic filed. To get the synergistic effect of multiple mechanisms and the contributions for Sb(V) removal, it discusses the relationship between the Sb removal enhancement and the surface properties according to the analysis of surface potential, adsorption capacity and surface structure, and also investigates the adsorption and desorption behavior. This study will provide an academic and technical direction for the efficient removal of Sb(V) in low concentration.

锑对人体健康的危害逐渐清晰且人类社会活动导致锑污染加剧，然而关于有效去除水中锑，特别是微量锑的研究相对缺乏。尽管铁氧化物被证实可有效去除水中的锑，但基于除矿区外水中的锑浓度基本处于几~几十μg/L的很低范围，锑受扩散梯度限制难以快速迁移至铁氧化物的吸附位点，导致实际除锑效率很难达到预期。本项目拟采用荷正电聚合物提供表面正电场，构建包含纳米铁氧化物为除锑功能材料的复合吸附剂，基体的正电场通过静电作用富集水中微量锑至铁氧化物的吸附位点，解决传质问题。研究包括调控复合吸附剂孔结构、正电荷密度、载铁量等因素，以解析附加电场与除锑效能之间的关系。复合吸附剂的静电场将进一步通过络合阳离子过渡金属得到提高。通过表面电位、吸附容量、表面形态变化等分析建立强化作用的相应关系，并系统研究复合吸附剂对锑的吸附及解吸规律，探索多重作用机理的协同机制和贡献，以期对高效去除水中微量锑提供有益的理论和技术探索。

吸附除锑因水中锑浓度低，向吸附剂表面扩散受限，导致吸附效率不高。本项目构建以醋酸纤维素（CA）为骨架、壳聚糖（CS）表面质子化胺基提供正电的复合载铁吸附剂（CS/CA-Fe），并通过表面调控优化其去除五价锑[Sb(V)]的效能；研究阳离子过渡金属强化其吸附除锑特性，通过材料表征、吸附效能、吸附动力学、热力学以及除锑影响因素分析等探讨多重作用协同除锑机制。结果显示：CS/CA-Fe中CS与CA的最佳比例为1:4。吸附剂中铁以水合氧化铁（HFO）的形式存在，载铁量为41.3 mg/g。与CS/CA相比，CS/CA-Fe对Sb(V)的去除率在pH4.0~8.5范围内增加26.3%~55.8%。经筛选，Cu2+与Sb(V)共存且pH≥5.0时，CS/CA-Fe对Sb(V)的去除率受pH影响进一步减弱，其对Cu2+与Sb(V)的吸附容量按大小排序为QSb+Cu＞QSb+QCu，是Cu2+与Sb(V)在CS/CA-Fe表面发生静电层层吸附所致。结合pH、离子强度和竞争离子的影响以及XPS分析发现静电吸附是CS/CA-Fe除锑的主导作用，静电吸附富集引起的协同HFO除锑作用在pH5.0和pH6.0较为显著。本项目对构建稳定高效去除水中微量锑的吸附剂具有理论和技术支撑。