共沉淀—超滤去除原水中锑的研究

发布时间：2018-09-18 19:33

【摘要】：随着我国锑工业的不断发展,锑的使用在我国呈现上升趋势,目前我国的锑工业发展方式为粗放型非可持续发展,因此锑污染问题也成为现代的重金属污染方面的热点问题。锑污染主要分布于空气、土壤和水体中,人们通过饮水、呼吸、食品等各种途径接触到环境中的锑。锑主要是对人体的皮肤、内脏以及呼吸道等有一定的损害。考虑到锑对人体的毒害和致癌性,许多国家对锑都制定了严格的环境标准。我国生活饮用水卫生标准规定生活饮用水中锑的含量不得超过5μg/L。本课题利用共沉淀-超滤去除原水中微量的重金属Sb。研究首先比较了各种铁、铝共沉剂的除锑效果。结果表明铁锑共沉剂的除锑效果要明显好于铝锑共沉剂,实验还研究了各种影响因素对共沉淀-超滤除锑的效果影响(如搅拌时间、pH值、温度等),经共沉淀后的溶液取其上清液再经超滤处理,其出水中锑的浓度能够满足标准要求。最后还对超滤膜的污染机理与清洗方法进行了分析研究。本课题利用共沉淀—超滤工艺去除锑的主要机理是：共沉剂的水解沉淀产物通过表面吸附、包藏(吸留)和生成混晶成固溶液等作用,在水中与锑酸根及其它锑离子发生共沉淀,而后未被沉淀去除的一部分无定形沉淀、胶体或大分子溶质等被超滤膜筛分截留。本课题还分析了几个影响因素对除锑效果的影响：(1)共沉剂投加量：共沉剂投量对共沉淀-超滤工艺除锑的影响,随着共沉剂投加量的增加,对锑的去除率逐渐增大,当原水中的氯化铁投加量为10mg/L时,对原水中锑的去除率达到86.74%,取沉淀上清液经超滤膜后,锑的去除率为96.96%,此后再增加共沉剂的投加量,锑的去除率没有明显的提高。(2)搅拌时间,搅拌时间的长短对除锑效果的影响主要取决于沉淀形成时吸附杂质离子所需要的时间,搅拌时间不够沉淀还没有形成；从而影响除锑的去除率。搅拌时间过长,则会形成沉淀陈化现象,同样影响锑的去除率。试验确定最佳搅拌时间为5～10min。(3)pH值,原水的pH值对共沉淀—超滤工艺除锑的效果有显著影响,最终确定在中性条件(pH6～8)是共沉淀—超滤工艺除锑的最佳pH范围,在此范围内对锑的去除率达95%以上。(4)温度,本试验温度对除锑效果影响很小,在温度为30度左右其除锑效果最佳,在室温20度左右时,对原水中的锑的去除率能达到95%以上。不过研究还发现在低水温的条件下,除锑效果良好,但是膜污染严重,所以得出水温是膜污染的重要影响因素之一。动态实验表明：在连续进水的条件下,调节原水进水浊度,测得出水浊度及锑浓度值均能符合饮用水要求,共沉淀-超滤工艺除锑效果显著,此工艺对含锑微污染原水的治理方面有较好的应用前景。
[Abstract]:With the continuous development of antimony industry in our country, the use of antimony is on the rise in our country. At present, the mode of development of antimony industry in our country is extensive non-sustainable development, so the problem of antimony pollution has also become a hot issue in the field of heavy metal pollution in modern times. Antimony pollution is mainly distributed in air, soil and water. People come into contact with antimony in the environment by drinking water, breathing and food. Antimony is mainly to the human skin, viscera and respiratory tract damage to a certain extent. Considering the toxicity and carcinogenicity of antimony, many countries have set strict environmental standards for antimony. The sanitary standard for drinking water in China stipulates that the antimony content in drinking water shall not exceed 5 渭 g / L. Removal of trace heavy metal Sb. from raw water by coprecipitation-ultrafiltration The antimony removal effects of various iron and aluminum co-precipitators were compared. The results show that the antimony removal effect of iron antimony co-precipitation agent is better than that of aluminum antimony co-precipitation agent. The effect of various factors on antimony removal by coprecipitation-ultrafiltration (such as stirring time, pH value) is also studied. The concentration of antimony in the effluent can meet the standard requirement when the supernatant is taken from the solution after coprecipitation and then treated by ultrafiltration. Finally, the fouling mechanism and cleaning method of UF membrane were analyzed and studied. The main mechanism of antimony removal by coprecipitation-ultrafiltration process is that the hydrolytic precipitation product of coprecipitation agent is adsorbed by surface, encapsulated (retained) and formed mixed crystal solid solution, etc. A part of amorphous precipitate was precipitated with antimony and other antimony ions in water, and the colloid or macromolecular solute was cut off by ultrafiltration membrane. The effects of several factors on antimony removal are also analyzed: (1) the amount of co-precipitation agent: the effect of the amount of co-precipitation agent on antimony removal by coprecipitation-ultrafiltration process, with the increase of the amount of co-precipitation agent, the removal rate of antimony increases gradually. When the amount of ferric chloride in raw water is 10mg/L, the removal rate of antimony in raw water reaches 86.74. The removal rate of antimony is 96.96 when the precipitation supernatant is taken from the supernatant through ultrafiltration membrane, and the removal rate of antimony is not obviously increased when the amount of co-precipitation agent is increased afterwards. (2) stirring time, The effect of stirring time on antimony removal is mainly determined by the time required to adsorb impurity ions at the time of precipitation formation, but the stirring time is not enough to precipitate, thus affecting the removal rate of antimony. If the stirring time is too long, the precipitation and aging will be formed, and the removal rate of antimony will also be affected. The optimum stirring time is 5 ~ 10 min. (3) pH value. The pH value of raw water has a significant influence on the antimony removal effect of coprecipitation-ultrafiltration process. Finally, it is determined that the best pH range of antimony removal in coprecipitation-ultrafiltration process is under neutral conditions (pH6~8). In this range, the removal rate of antimony is over 95%. (4) the temperature has little influence on the antimony removal effect. The antimony removal efficiency is the best when the temperature is about 30 degrees, and the removal rate of antimony in the original water can reach more than 95% when the temperature is about 20 degrees. However, it is also found that the antimony removal effect is good under the condition of low water temperature, but the membrane fouling is serious, so the water temperature is one of the important influencing factors of membrane fouling. The dynamic experiments show that under the condition of continuous influent, the turbidity of raw water and the concentration of antimony can meet the requirements of drinking water, and the antimony removal effect of coprecipitation-ultrafiltration process is remarkable. This process has a good application prospect in the treatment of raw water containing antimony.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU991.2

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