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题名: 磁性铁基吸附剂去除水中锑的研究
作者: 齐增禄1
学位类别: 博士
答辩日期: 2017-06
授予单位: 中国科学院大学
授予地点: 北京
导师: 曲久辉 ; 刘锐平
关键词: 吸附,磁性吸附剂,磁分离,锑,水处理 ; Adsorption, magnetic adsorbent, magnetic separation, antimony,water treatment
其他题名: Removal of Antimony from water by Iron-based Magnetic Adsorbent
学位专业: 环境工程
中文摘要: 锑元素被认为对所有生命形式都具有高度毒性,已被世界卫生组织分类为强 致癌物质。环境中的锑可经由摄入污染的水、食物或者空气进入人体而影响健康。 饮用水锑污染是一个世界性问题,开发可高效去除水中锑的方法已成为研究人员 的一个重要挑战。吸附作为一种成熟、经济、简单的水处理方式已广泛应用于饮 用水中污染物的去除。但使用后吸附剂与出水的“固 -液分离”是限制吸附工艺 应用的主要问题。近年来发展的磁性铁基吸附剂可借助磁场以比传统沉淀过滤法 快几百倍的进行固-液分离。通过在合成过程中向 Fe3O4磁性颗粒中掺杂其他元 素(X-doped Fe3O4,X=Cu,Ce,Mn等)可大大提高其对水中锑去除能力,同 时还能够保留足够的磁分离特性。更进一步,“磁性铁基吸附剂-磁分离”联用工 艺将有效解决吸附剂的“固-液分离”难题,对高效、低成本水处理技术的开发 具有重要意义。 论文首先研究比较了非掺杂和 Cu掺杂 Fe3O4对水中 Sb(III)和 Sb(V)的去除 能力和机理。研究发现,与非掺杂的 Fe3O4相比较,Cu掺入 Fe3O4使其表现出更 小的颗粒尺寸和较低的饱和磁化强度,同时极大提高其对水中锑的去除能力。其 中,非掺杂 Fe3O4在 pH 7.0下显示出 34.46 mg Sb(III) g-1和 7.07 mg Sb(V) g-1的 最大吸附容量(Qmax)。Cu的掺杂将吸附剂的 Qmax分别提高至 43.55 mg Sb(III) g-1 和 30.92 mg Sb(V) g-1。共存的硫酸根和碳酸根离子对吸附量影响很小,而 10 mM 磷酸根的存在可使 Cu-doped Fe3O4的 Sb(III)和 Sb(V)吸附容量分别减少 14.1%和 58.6%。吸附过程中溶液中 Sb价态分析结果表明, Cu-doped Fe3O4表面的 “≡Cu -O”比“≡Fe -O”位点具有更强的氧化活性,同时溶液中溶解氧量并不 对水中 Sb被氧化量有影响。由此推测,电子从 Sb(III)到 Cu(II)转移时会形成 Cu(I) 和 Sb(V)并向溶液中释放,然后 Cu(I)会随之歧化反应而产生 Cu(II)离子和 Cu(0) 沉淀。 为进一步提高磁性吸附剂对水中 Sb(V)的去除效率,采用溶剂热法将 Ce(III) 掺杂到 Fe3O4中合成铈掺杂 Fe3O4磁性吸附剂,并考察了不同 Ce:Fe掺杂比例 条件下其对 Sb(III)和 Sb(V)的吸附效果。基于 XPS,XRD和 FT-IR等表征综合结 果,证实 Ce原子成功掺入到 Fe3O4结构中,同时可导致吸附剂的粒径减小以及 表面积和等电点的上升。与未掺杂 Fe3O4相比,Ce掺杂材料的 Sb(III)和 Sb(V) 吸附能力分别从 111.4增加到 224.2 mg g -1以及从 37.2增加到 188.1 mg g-1。此外, 拥有最大掺杂量(Fe:Ce=5:5)的 Ce-doped Fe3O4在仅 76 mT磁场条件下 10 min 内即可完全固液分离。 新型磁性铁基吸附剂研究基础上开发了“磁性吸附剂 -超导磁分离”水处理 工艺。研究首先验证了 MnFe2O4对水中 As和 Sb的吸附行为,之后通过现场连 续流实验评估了“吸附-超导磁分离”技术的应用可行性。MnFe2O4纳米颗粒能 够在 6 h内去除水中 98.6%的 As和 91.6%的 Sb,同时促进 As(III)和 Sb(III)氧化。 该工艺“吸附段”完成后,含有磁性吸附剂的混合液进入超导高梯度磁分离系统 进行固液分离。结果表明,该系统的磁截留容量取决于“磁场梯度”、“混合液流 速”以及“钢丝填充比例”。3.0 T磁场与无磁场条件相比,系统对 MnFe2O4颗粒 的捕集能力增加超过 3倍。此外,流速从 1.0 L min-1 增加到 3.0 L min-1可将磁性 吸附剂穿透点从 35分钟提前到 15分钟。当钢丝填充率从 5%降低到 3%,由于 有效捕获区域的减少,系统捕获能力下降 13.7%。该系统对天然污染河水样品中 As、Sb的去除效率分别高达 94.6%和 76.8%。 以上研究成果表明,利用溶剂热法掺杂元素至 Fe3O4磁性颗粒对提升磁性吸 附剂锑的去除效率是十分有效的,同时也验证了“吸附 -磁分离”联用工艺具有 良好的应用前景,该论文为学科交叉强化水处理技术奠定了坚实的理论和实践基 础。
英文摘要: Antimony is considered to be highly toxic to all life forms and have been classified as strong carcinogenic by the World Health Organization. Antimony in the environment can affect human health by ingesting through contaminated water, food, and air into the human body. Antimony contamination of drinking water is a worldwide problem, and the development of methods for efficient removal of antimony from water has become an important challenge for researchers and even policymakers. Adsorption as a mature, economical, and simple water treatment has been widely used to remove contaminants from drinking water. However, the difficulty of the "solid-liquid separation" of the adsorbent after adsorption process is a major problem in the practical application. The magnetic iron-based adsorbents developed in recent years can be separated solid-liquid by a magnetic field. The doping of other elements (X-doped Fe3O4, X = Cu, Ce, Mn, and so on) to the Fe3O4 magnetic particles in the synthesis process can greatly improve its ability to remove antimony from water. Furthermore, the "magnetic iron-based adsorbent " process will effectively solve the solid-liquid separation problem of nano adsorbents, which is of great significance to the development of high efficiency water treatment technology. In this study, the removal ability and mechanism of non-doping and Cu-doped Fe3O4 on Sb (III) and Sb (V) from water were studied. It was found that the doping-Cu exhibited lower particle size and saturation magnetization compared with non-doped Fe3O4, but greatly improved the adsorption capacity. Among them, the undoped Fe3O4 showed the maximum adsorption capacity (Qmax) of 34.46 mg-1 Sb (III)g-1and 7.07 mg Sb (V) g-1 at pH 7.0. Doping Cu can increase Qmax to 43.55 mg Sb (III), respectively. The adsorption capacity of Sb (III) and Sbg-1and 30.92 mg Sb (V) g-1(V) of Cu-doped Fe3O4 was reduced by 14.1% and 58.6%, respectively, while the effect of coexisting SO42- or CO32- ion on the adsorption was negligible. The results exhibited that the "≡Cu -O" sites on the surface of Cu-doped Fe3O4 had stronger oxidative activity than "≡Fe -O" sites, and the amount of dissolved oxygen in the solution was not affected by the amount of Sb oxidized in water. It is speculated that Cu (I) and Sb (V) formed when electrons transferred from Sb (III) to Cu (II) and the generated Cu (I) tend to be released into the solution. The Ce-doped Fe3O4 adsorbent was successfully synthesized by similar methods. Compared with un-doped Fe3O4, the adsorption capacity of Sb (III) and Sb (V) of Ce-doped Fe3O4 increased from 111.4 to 224.2 mg g-1 and from 37.2 to 188.1 mg g -1 , respectively. Based on the results of XPS, XRD, and FTIR, it was confirmed that Ce atoms were successfully incorporated into Fe3O4 structures, which resulted in the decrease of particles’ size, confirmed by SBET surface area and isoelectric point. In addition, the doping of Ce has some negative effects on the original magnetic properties, but the Ce-doped Fe3O4 with the maximum doping amount (Fe:Ce =5:5) can be separated solid-liquid completely within 1 min by only 76 mT magnetic field. Based on the developed iron-based magnetic adsorbents, this study also developed an innovative "magnetic adsorbent-superconducting magnetic separation" water treatment process. Nano iron-based adsorbent MnFe2O4 had good removal effect on arsenic and antimony in water, but its application was also limited by the difficulty of solid-liquid separation. In this study, the adsorption behavior of MnFe2O4 on As and Sb in water was verified, and the feasibility of "adsorption-superconducting magnetic separation" was evaluated by pilot-scale experiment. MnFe2O4 nanoparticles removed 98.6% As and 91.6% Sb in water at 6 h, influencing oxidation of As (III) and Sb (III). After the adsorption process completed, the mixture with the adsorbents entered the superconducting high gradient magnetic separation system for solid-liquid separation. The results showed that the magnetic trapping capacity of the system depends on the magnetic field strength, flow rate, and ratio of the wire filling. Compared with the non-magnetic field, this system increased the trapping ability of MnFe2O4 particles by more than 3 times. In addition, the flow rate was increased from 1.0 L min-1 to 3.0 L min-1 , moved the leak point from 35 minutes to 15 minutes. When the wire filling rate was reduced from 5% to 3%, the system trapping capacity was reduced by 13.7% due to the reduction of the effective capture area. The system showed excellent removal of As and Sb in river water samples. The removal efficiency was achieved 94.6% and 76.8% before MnFe2O4 leakage. Based on the above research results, the water treatment process based on magnetic separation and adsorption has a good application prospect, which will lay a theoretical and practical foundation for future related processes.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/38684
Appears in Collections:环境水质学国家重点实验室_学位论文

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作者单位: 1.中国科学院生态环境研究中心

Recommended Citation:
齐增禄. 磁性铁基吸附剂去除水中锑的研究[D]. 北京. 中国科学院大学. 2017.
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