【作者】 江喆；

【导师】 普红平；

【作者基本信息】 昆明理工大学 ， 环境工程， 2005， 硕士

【摘要】 随着我国社会经济的迅速发展,原来并不为人们所关注的砷污染日益严重。由于砷化物具有较大的毒性且在工农业生产中广泛应用,砷对环境的污染特别是对水质污染的问题,已引起全世界环境科学工作者的普遍关注。另外,由于天然砷矿蕴藏,目前我国某些地区地下水砷本底含量过高,超过饮用水最大允许值即25～50×10^-9,对当地居民造成慢性危害。据报导,通过各种途径进入水圈的砷,全世界每年约11万吨。因此,寻找一种除砷彻底,操作简单,成本低廉的水质除砷方法,对含砷废水处理和饮水净化有着现实意义。 沸石,作为一种廉价的非金属矿物,具有良好的吸附、交换性能,对微小颗粒有富集作用,是一种理想的载体。通过对沸石的改性处理能够大大提高其对目标离子的去除能力,特别是斜发沸石和丝光沸石在这方面具有良好的应用前景。国内外对沸石去除水中主要污染物,如氨氮,磷等已作了较多研究,但有关利用其去除水质砷方面还鲜见报道。研究表明,利用沸石处理水中的污染物时存在一突出矛盾:沸石粒径越小,吸附交换容量越高,对污染物去除效果越好,但粒径太小沸石易随出水流失,影响出水水质,增大装置的水头损失。若采用较大的粒径则必须以牺牲吸附容量为代价。 为解决这一问题,本文着手研制改性微孔沸石颗粒,首先选出最佳的沸石改性方法及该方法的最佳改性条件,将经改性处理的沸石烧制成球形颗粒;然后研究所制备的改性沸石球对水中五价砷的去除效果,详细考察了沸石投加量、处理液浓度、沸石粒度、温度、时间、pH等因素对砷（V）去除的影响规律;最后研究了改性沸石球再生的方法及效率。同时,还用改性沸石球对实际的微污染水样进行了处理,并对其去除氨氮、氟离子和磷酸根离子作了初步研究。 通过本课题的研究得出以下结论,利用稀土（LaCl₃）改性能够大大提高沸石对砷（V）的去除能力,平均去除率提高了30%以上,其改性效果优于加热、酸（HCl）浸和碱（NaOH）浸的方法。考虑技术和经济等因素的影响,取最佳的质量分数浓度为0.5%的LaCl₃溶液对沸石进行改性,操作条件如下:pH值为10,按1:25（固液比）投加沸石,浸渍2～3h,过滤烘干后,于500～600℃下焙烧1h。改性微孔沸石球制备的最佳条件是,原料配比为改性沸石（-200目）:造孔剂（木炭粉）:粘合剂（淀粉）=89:9:2,沸石球粒径3mm,烧制温度500～600℃,保温时间2h。 对改性沸石球除砷（V）的影响因素研究表明,研制的改性沸石球适于处理pH=4～10的废水,对含砷（V）浓度为10mg/L的模拟溶液,当投加量为8g/L时,更多还原

【Abstract】 With the rapid development of the social economy and technology, the pollution of arsenic unknown in the past is increasingly serious in the water source. Recently, because the arsenic compounds are lethal toxicants and widely-used in the agriculture and industry, environmental scientists around the world have paid attention to the problems brought out by arsenic compounds that contaminates the environment, especially in the water sources. On the other hand, due to the abundant reserves of arsenic, the background concentration of arsenic is much higher than the maximum standards of drinking water that is 25⁵0×10^-9, in the groundwater in some areas of China, so that it does some chronic harm to local people. And according the records, there are about 110,000 tons of arsenic compounds by different means to enter the hydrosphere every year. Therefore, it makes important sense to develop a thorough, simple and economical method to remove the arsenic from the wastewater or drinking water source at present.As a low-priced nonmetallic mineral that have good selective adsorption and ion exchange characteristics, zeolites can enrich much fine particles and be regarded as ideal medium. The removal efficiency of target ions can be greatly enhanced by modifying zeolites, such as clinoptilolite and mordenit, etc, which have potential prospect in the reality. Either in China or outside, there are many studies that mostly focuses on the removal of NH₄⁺-N and phosphate while the researches on removing arsenic from wasterwater or drinking water are rarely seen. Historically, there is an outstanding contradiction that is between the size of zeolites and removal efficiency when using zeolites for removing some pollutants from water solutions. The smaller is grains, the higher exchange and adsorption capacity and the better efficiency can be achieved, however, the more loss of zeolites with the effluent and the head loss influencing the quality of effluent. On. the contrary, to take larger grain must be at expense of sacrificing of adsorption capacity.To solve this problem, the study began to prepare of porous modified zeolite pellets. Firstly, the study selected the proper method of modification and the optimumconditions for preparing, and made the modified zeolite pellets by burning. Then, the removal efficiency of arsenic（V） by zeolite pellets and the factors influencing the efficiency, as pellet size, zeolite amout, treating time, pH and temperature, etc. were investigated thoroughly. Finally, the regeneration method and efficiency of zeolite had also been studied. Meanwhile, the modified zeolite pellets was used to treat real wastewaster for compare with the lab outcomes, and initially studied the removal performance in the NH₄⁺-N, phosphate and fluoride, respectively.Through the research of this paper, the conclusion can be drawn. Compared with other treatments, such as treatment with sintering, hydrochloric acid （HC1） and sodium hydroxide （NaOH）, the removal efficiency can be greatly enhanced by treatment with lanthanum chloride （LaCl₃）, the average removal efficiency increased by 30%. Thinking of the technological and economic effects, the optimum condition of modification was confirmed. The modifying concentration of LaCl₃ solution is 0.5% by weight, the zeolites should be soaked for 2 to 3 hours and the total solid/liquor is 1:25 under the pH=10. After done, the sample is sintered at temperature of 500⁶00℃ for an hour. The proper conditions of preparing modified zeolites pellets were also presented. The raw materials matching ratio as follows: the modified zeolites（-200 mesh）: additive forming pores（charcoal powder）:binder（soluble starch） = 89:9:2 under the 500⁶00℃, and the diameter of pellets is 3mm, reserve time is 2 hours.It indicated by study on the factors influencing efficiency that the modified zeolite pellets are suitable to treat the simulated wastewater containing lOmg/L of arsenate with the pH being 4¹0. The removal efficiency of arsenic（V） can be achieved above 95% by using about 8g/L pellets, as requirements of the National Drainage Standard. The modified zeolite pellets can also be used to remove NH₄⁺-N, phosphate and fluoride from water solution to some extent. In the study, when the modified zeolite pellets was regenerated by NaOH solution with the concentration being 1.0mol/L and treating time being 3⁴ hours, the removal efficiency of As（V） had been slightly deceased by 5% after recycling at least 10 times. Therefore, it showed that the sample also has the high strength of compressive resistance, the modified zeolitepellets can be put into practice for multiple regenerations.Gradually, as the requirements of standard of removing arsenic are strict, it must call on more and more breakthroughs and improvements further either in the fields of wastewater or drinking water. The objective of this study is to provide the new technique to remove arsenic from water solution, efficiently and economically.更多还原