| 题名 | 凝聚-吸附去除饮用水中典型有害阴离子的应用研究 |
| 作者 | 何赞 |
| 学位类别 | 博士 |
| 答辩日期 | 2015-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 刘会娟 ; 曲久辉 ; 刘锐平 |
| 关键词 | 除锑，砷锑竞争吸附，除氟，混凝，吸附，铝氟络合，Sb removal, the competitive adsorption of As and Sb, fluoride removal, coagulation, adsorption, Al-F complexation |
| 其他题名 | The removal of typical toxic anions from drinking water by coagulation and adsorption and its application |
| 学位专业 | 环境工程 |
| 中文摘要 | 特殊污染物控制是饮用水领域的重要研究内容，砷、锑、氟等是饮用水源中常见的有毒阴离子，如何有效去除控制上述污染物是国内外高度关注的难题。 天然水体中砷主要以 As(III)和 As(V)的形式存在，电中性 As(III)较电负性As(V)更难去除，将As(III)氧化为As(V)再通过后续吸附工艺去除，这是饮用水除砷的最佳去除策略。铁锰复合氧化物可实现 As(III)和 As(V)的同时一步去除。锑和砷为同族元素，二者有不少相似的化学性质。但研究显示，Sb(III)较Sb(V)更容易去除，锑的最佳去除策略为还原-吸附，但在工程层面上实现 Sb(V)还原非常困难。因此，开发高效除锑吸附材料尤为必要。为此，本研究以铁盐原位水解反应为基础制备了具有巨大比表面积和丰富吸附位点的吸附剂 in-situ FeOxHy。研究显示，in-situ FeOxHy 可同时高效去除 Sb(III)和 Sb(V)，且二者在其表面均主要生成内层络合物。在 pH=5 时其对 Sb(III)和 Sb(V)的最大吸附容量分别为12.77 mmol/g和 10.21 mmol/g，且 Freundlich模型能够很好的描述其吸附过程。在 pH为 3-10范围内，Sb(V)吸附量随着 pH升高而降低而 Sb(III)吸附量却增加，这主要是由二者的主要形态带有相反的电荷所致。硫酸盐和碳酸盐对二者的吸附影响不大，磷酸盐显著抑制 Sb(V)的吸附但对 Sb(III)吸附影响很小。连续流动态试验证实了 in-situ FeOxHy工程应用的可行性，其平衡吸附容量为 1 mg/g，pH和载体大小为其主要工艺控制参数。 国内外对具有相似化学性质的砷和锑在共存体系下的竞争吸附行为研究较少。研究显示，二者在共存体系存在复杂的竞争吸附行为，且不同形态砷锑之间的竞争作用有明显不同。具体而言，不同形态的砷和锑在羟基氧化铁上发生竞争吸附时，二者吸附量均较单一体系发生不同程度下降。就吸附速率而言，Sb(III)会降低 As(III)的吸附速率，而 As(III)会提高 Sb(III)的吸附速率；Sb(V)会提高As(III)的吸附速率，而 As(III)会降低 Sb(V)的吸附速率；As(V)和 Sb(V)均能促进彼此的吸附速率；As(V)会提高 Sb(III)的吸附速率，而 Sb(III)会降低 As(V)的吸附速率。此外，研究发现，二者引入先后顺序和间隔时间对竞争吸附行为也有影响，二者引入时间间隔对吸附剂总的吸附量影响不大，但间隔时间越长则先引入的离子最终吸附量越大，反之后引入的离子吸附量越小。表面络合模型结果显示，As(V)和 Sb(V)在羟基氧化铁表面均形成单齿双核络合物。羟基氧化铁表面有两类羟基：一类为 As(V)和 Sb(V)共有吸附点位，二者在此吸附点位可竞争吸附；另一类为 Sb(V)的专属吸附点位。 目标污染物与吸附剂之间的相互作用将对彼此的形态产生影响，进而显著影响污染物去除性能，但国内外对此关注较少。以铝盐除氟过程为基础，系统研究了基于铝盐凝聚与吸附过程的铝、氟形态相互作用，并在此基础上研究了铝盐混凝和 in-situ Al2O3•xH2O吸附除氟性能与机制。研究显示，铝盐混凝除氟效果优于 in-situ Al2O3•xH2O吸附，实现某实际高氟地下水达标的铝投量分别为 30和 160mg/L，且最佳 pH 范围均为 6-7。在混凝除氟过程中铝盐水解消耗水中碱度，并发生了自由态氟向络合态氟的转化，且提高铝投量可促进络合态氟的形成；对比而言，吸附过程中络合态氟生成量很少。氟离子的存在会影响铝离子水解，并可有效促进溶解态铝离子和铝氟络合体向颗粒态沉淀的转化。另一方面，铝氟络合作用会促进 in-situ Al2O3•xH2O铝离子的溶出和释放，且在酸性 pH和高氟铝比条件下更为显著。这降低了可用于吸附除氟的有效 in-situ Al2O3•xH2O沉淀含量，进而对氟的去除产生不利影响。现场中试试验证实，铝盐混凝除氟优于in-situAl2O3•xH2O吸附除氟，氟达标的平衡吸附量分别为 85.2和25.1 mg F/g Al；铝氟络合体生成对于混凝除氟表现出更佳的除氟性能具有重要作用。 受地球环境化学的作用，有时会出现砷氟共存现象。应用 in-situ Al2O3•xH2O同时去除砷氟结果显示， 铝氟络合作用和氟吸附到 in-situ Al2O3•xH2O表面降低的 zeta 电位会降低 As(V)的吸附，而 As(III)的去除受氟的影响很小。电负性的As(V)对氟吸附的抑制作用要远远大于 As(III)。 铁、铝盐凝聚与原位生成的金属氧化物吸附可有效去除水中砷、氟、锑等有害阴离子，而污染物与絮凝剂、吸附剂之间的相互作用对其去除有重要影响。 |
| 英文摘要 | The removal of typical pollutants is one of the most important study areas in the drinking water, and arsenic, antimony and fluoride are the common toxic anions in the drinking water source. Therefore，how to effectively control the above pollutants is highly concerned by the researchers at home and abroad. In natural water, As mainly exists in the inorganic forms of As(III) and As(V), and electroneutral As(III) is more difficult to be removed than the negatively charged As(V). The optimum removal route of arsenic in water is oxidized firstly and then adsorbed, and Fe-Mn Binary Oxide can achivie a step efficient removal of As(III) and As(V). Arsenic and antimony locate in the same group in the elements periodic and have the similar chemical property whereas researches indicate that the optimum removal route of antimony is reduced firstly and adsorbed afterward. However, the above process is difficult to be achieved in the actual engineering, and thus it is another essential path to look for an adsorbing material for removing antimony effectively. For this aim, this study successfully prepared a novel adsorbent with high specific surface area and adsorptive activity, i.e., in-situ FeOxHy. This study indicated that in-situ FeOxHy can effectively remove Sb(III) and Sb(V), and the formation of inner-sphere complexes was involved between Sb and the adsorbent. The maximum adsorption capacity of Sb(III) and Sb(V) was determined to be 12.77 and10.21mmol/g as Fe,respectively, at pH of 5 and Freundlich model was better than Langmuir model to describe the adsorption of Sb(III) and Sb(V). Adsorption of Sb(V) decreased whereas that of Sb(III) increased with elevated pH over pH 3-10, owing to the different electrical properties of Sb(III) and Sb(V). Sulfate and carbonate showed little effect on the adsorption of Sb(III) and Sb(V). Phosphate significantly inhibited the adsorption of Sb(V), whereas slightly affected that of Sb(III). Pilot-scale continuous experiment indicated the feasibility of using in-situ FeOxHy to remove Sb(V) and the equilibrium adsorption capacity at the equilibrium Sb(V) concentration of 10 μg/L was determined to be 1 mg/g, and pH and good porosity was essential for removing Sb. The competitive adsorption of As and Sb is rare to be studied. The competitive adsorption kinetic of different species As and Sb on iron hydroxides indicated that they affected the adsorption of each other. In term of adsorption rate, Sb(III)decreased the adsorption rate of As(III) whereas As(III) increased of that of Sb(III);Sb(V) favored the adsorption rate of As(III) whereas As(III) inhibited that of Sb(V);As(V) and Sb(V) elevated the adsorption rate of each other; As(V) favored the adsorption rate of Sb(III) whereas Sb(III) inhibited that of As(III). The effect of adding time of the competitive ion on the first ion added showed that the adding time barely affect the total adsorption capacity of the adsorbent, and the time of adding competitive ion is later, the adsorption capacity was higher for the first ion added whereas it was smaller for the competitive ion. The results of surface complexes model indicated that the formation of monodentate binuclear complexes between As(V) or Sb(V) and iron hydroxides. Iron hydroxides has surface sites into two types: ones to which both As(V) and Sb(V) adsorb and a smaller number to which only Sb(V) binds. The interaction between the targeted pollutant and the adsorbent will affect the species of each other and show significant effect on the removal of pollutants afteraward. The mutual effect between Al and F in the fluoride removal by Al-based coagulation and adsorption was systematically investigated in this study, and the removal property and mechniasm of fluoride by Al-based coagulants and in-situ Al2O3•xH2O adsorbent was also conducted. The results indicated that Al coagulation showed superiority to remove flruoride than Al precipitate did. To achieve the maximum contaminant level (MLC) of fluoride (<1 mg/L) in drinking water standard,the optimum Al doses were determined to be 30 and 160 mg/L in coagulation and adsorption process for the actual underground water, respectively, and the optimum pH for the fluoride removal was pH of 6-7. In the coagulation system, the formation of complexed fluoride occurred and it was elevated with the increasing of Al doses whereas it barely occurred in the adsorption system. Fluoride affected the Al3+ hydrolysis and contributed to the transformation of Al3+ and Al-F complexes into precipitate. However, the complexed reaction between Al and fluoride caused the dissolution of in-situ Al2O3•xH2O, which was most important at low pH and high ratio of fluoride to Al conditions, and reduced the precipitate available for fluoride removal afterwards. Pilot-scale filed experiment indicated that Al-based coagulation showed better fluoride removal than adsorption did, and the equilibrium adsorption capacity at the equilibrium fluoride concentration of 1 mg/L was determined to be 85.1 and 25.1 mg F/g Al, respectively. The formation of Al-F complexes was important for the better removal of fluoride by Al coagulantion. In some cases with special geochemical conditions, the simultaneous occurrence of As and F is observed. The simultaneous removal of As and F was investigated by in-situ Al2O3•xH2O adsorption, and the results indicated that the reduced removal of As(V) was observed owing to the Al-F complexed reaction and the reduced zeta potentian of in-situ Al2O3•xH2O after adsorping fluoride whereas the removal of As(III) was rarely affected by the coexisting fluoride. The negatively charged As(V) showed higher inhibitive effect on fluoride than As(III). Arsenic, antimony, and fluoride can be effectively removed by Al or Fe-based coagulants and the in-situ formed metal oxide, and the interaction between the pollutants and coagulants or adsorbents showed significant effect on their removal. |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/34330]  |
| 专题 | 生态环境研究中心_环境水质学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 何赞. 凝聚-吸附去除饮用水中典型有害阴离子的应用研究[D]. 北京. 中国科学院研究生院. 2015. |
| 个性服务 |
| 查看访问统计 |
| 相关权益政策 |
| 暂无数据 |
| 收藏/分享 |
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。
修改评论