原位生成二氧化锰对水中微量重金属的去除效能与机制研究

发布时间：2018-06-04 12:01

  本文选题：二氧化锰 + 吸附　； 参考：《哈尔滨工业大学》2013年硕士论文

【摘要】：近年来我国频繁发生重金属污染事件，地表水源的重金属污染日趋严重。由于重金属具有毒性，能够产生生物富集并无法非生物降解，这使得水体的重金属污染引起了人们的广泛关注。常规水处理工艺不能有效去除水中重金属离子，应用于工业含重金属离子废水的处理技术由于处理规模有限，在净化饮用水源水质过程中并不适用，并且这些技术对水中微量重金属离子的去除效能不高，出水水质难以满足《生活饮用水卫生标准》（GB5749-2006）。吸附法被认为是去除水中重金属离子最有效的方法，缘于其具有适用浓度广、操作简单、易于规模化的优点。但常用吸附剂对重金属离子不具备高选择性和高吸附效能，因此有必要寻找高效能的吸附剂。本实验采用原位生成二氧化锰作为吸附剂，研究了其对重金属离子吸附去除效能的影响，并对去除机制进行了初步讨论。 本实验选取不同种类的氧化剂和还原剂，以高锰酸钾+硫酸锰、高锰酸钾+氯化锰、高锰酸钾+硫代硫酸钠、次氯酸钠+硫酸锰、次氯酸钠+氯化锰五种方式原位生成二氧化锰，通过对重金属离子去除效能的对比以及表征分析，选取高锰酸钾+硫酸锰为原位生成二氧化锰的最佳方式。 对原位生成二氧化锰去除水中重金属离子进行效能分析，结果表明其吸附量明显高于其他吸附剂，经Langmuir模型估算，对铅(Ⅱ)、镉(Ⅱ)、镍(Ⅱ)、锌(Ⅱ)、铜(Ⅱ)的最大吸附容量分别为625.00mg/g、138.66mg/g、104.21mg/g、81.60mg/g、240.49mg/g。原位生成二氧化锰对重金属离子的吸附速度快，目标物的去除率随二氧化锰投量和溶液pH的升高而显著增加。水溶液中存在的镁离子对去除效能基本没有影响，钙离子的存在能在有限程度内降低二氧化锰对重金属离子的吸附效率。氯离子、硝酸根、硫酸根对吸附效能不产生明显影响，碳酸根、磷酸根、硅酸根、硼酸根的存在可以有效促进二氧化锰对重金属离子的去除。不同种类的重金属离子与原位生成二氧化锰的亲和力不同，二氧化锰对铅(Ⅱ)具有远高于其他重金属离子的优先选择性。在实际水体中，原位生成二氧化锰能够有效去除微量重金属离子，在突发性污染事件中，具有极大的应用潜力。 X射线衍射表征结果显示，原位生成二氧化锰中可能存在二氧化锰晶体，表明其对重金属离子的去除是吸附和共沉淀共同作用的结果。傅立叶红外吸收光谱对比表明，，原位生成二氧化锰吸附重金属离子后，Mn-O特征吸收峰产生了偏移，可能有Pb-O、Cd-O、Ni-O、Zn-O、Cu-O生成，其来源是内球表面络合物的生成或重金属离子对锰产生的置换。X射线电子能谱表明，重金属离子被原位生成二氧化锰吸附后，特征峰出现偏移，有重金属离子对应的氧化物生成，进一步证明了二氧化锰吸附重金属离子的过程形成内球表面络合物。
[Abstract]:In recent years, heavy metal pollution has occurred frequently in China, and heavy metal pollution in surface water sources is becoming more and more serious. Due to the toxicity of heavy metals, bioconcentration and non-biodegradation can be produced, which makes the pollution of heavy metals in water attract widespread attention. The conventional water treatment process can not effectively remove heavy metal ions in water. Because of the limited scale of treatment, it is not suitable for purifying the drinking water source water in the process of treating industrial wastewater containing heavy metal ions. The removal efficiency of these technologies for trace heavy metal ions in water is not high, and the effluent quality is difficult to meet the sanitary standard of drinking water (GB5749-2006). Adsorption method is considered to be the most effective method for removing heavy metal ions in water because of its advantages of wide applicable concentration, simple operation and easy to scale. However, common adsorbents do not have high selectivity and high adsorption efficiency for heavy metal ions, so it is necessary to search for high efficiency adsorbents. In this experiment, manganese dioxide in situ was used as adsorbent to study the effect of manganese dioxide on the removal efficiency of heavy metal ions, and the removal mechanism was discussed. In this experiment, different kinds of oxidants and reductants were used, such as potassium permanganate manganese sulfate, potassium permanganate manganese chloride, potassium permanganate sodium thiosulfate, sodium hypochlorite manganese sulfate, etc. Manganese dioxide was produced in situ by sodium hypochlorite and manganese chloride. By comparing and characterizing the removal efficiency of heavy metal ions, potassium permanganate manganese sulfate was selected as the best way to produce manganese dioxide in situ. The efficiency of in situ manganese dioxide removal of heavy metal ions in water was analyzed. The results showed that the adsorption capacity of manganese dioxide was significantly higher than that of other adsorbents, which was estimated by Langmuir model. The maximum adsorption capacities of lead (鈪

本文编号：1977285