水溶液中邻苯二甲酸酯的氧化降解机理研究

发布时间：2018-10-22 15:24

【摘要】：邻苯二甲酸醋类(Phthalicacidesters, PAEs)塑化剂已被广泛用于各行各业,其环境风险已引起人们高度关注。环境中PAEs的内分泌干扰效应及其降解技术等为目前专家学者研究的热点,但其降解机理研究还较为薄弱。随着PAEs不断进入水体环境,传统工艺很难将其去除。为减少其潜在风险,深入开展水溶液中PAEs降解技术探索及机理研究显得非常重要。论文采用紫外光和过硫酸氢钾(Potassiumperoxymonosulfate,PMS)联用以及臭氧氧化的方法,对水体中的邻苯二甲酸异辛酯(Di(2-ethylhexyl)Phthalate,DEHP)降解效果及机理进行探讨。主要成果有:(1) UV/PMS体系降解DEHP的影响因素研究研究考察了 PMS、DEHP浓度、温度、pH值、环境中集中常见离子和腐殖酸对DEHP降解速率的影响。结果表明,①PMS与DEHP配比越高,降解速率常数越高,但DEHP浓度过高时会抑制反应速率;②加热能加快降解速率,并且是UV/PMS体系中一个重要的影响因素;③在不同pH条件下,酸性条件更适合UV/PMS降解DEHP;④环境中常见的Fe~(2+)、Co~(2+)、NO3-、HCO3-和腐殖酸对UV/PMS降解DEHP也有影响,除了腐殖酸对反应有抑制作用,其他离子都能够加快降解速率。(2)臭氧降解水中DEHP的影响因素研究研究考察了温度、pH值对降解速率的影响,结果表明,①温度升高能够加速臭氧降解DEHP的速率;②在pH为11时,速率常数kapp达到最高值0.011 min-1,即碱性条件更适合臭氧降解DEHP。(3) DEHP降解过程机制及机理研究研究首先对DEHP降解过程中的中间产物进行鉴别,确定其质荷比,然后高斯计算,推测DEHP的降解机理。结果表明,①UV/PMS降解DEHP过程中,共存在7个中间产物,3种降解路径,UV/PMS通过HO-自由基攻击和直接氧化结合的过程,在HO-和SO_4~(·-)共同作用下,HO-会加成在DEHP分子的苯环上。②臭氧降解DEHP的过程中,存在4个中间产物,2种降解路径;其主要降解机理也是通过自由基攻击DEHP和直接氧化的两种方式的结合,但在臭氧体系中,只有HO'攻击DEHP分子上的苯环,没有发生加成反应。
[Abstract]:(Phthalicacidesters, PAEs) plasticizer of phthalic acid vinegar has been widely used in various industries, and its environmental risk has been highly concerned. The endocrine disrupting effect and degradation technology of PAEs in the environment are the focus of experts and scholars at present, but the study of degradation mechanism of PAEs is still relatively weak. With the continuous entry of PAEs into the water environment, it is difficult to remove it by traditional technology. In order to reduce the potential risk, it is very important to explore the technology and mechanism of PAEs degradation in aqueous solution. The degradation effect and mechanism of iso-octyl phthalate (Di (2-ethylhexyl) Phthalate,DEHP in water were studied by UV light, potassium persulfate (Potassiumperoxymonosulfate,PMS) and ozone oxidation. The main results are as follows: (1) the effects of concentration of PMS,DEHP, temperature, pH value, concentration of common ions and humic acid on the degradation rate of DEHP in UV/PMS system were investigated. The results show that the higher the ratio of 1PMS to DEHP is, the higher the degradation rate constant is, but the higher the concentration of DEHP is, the higher the reaction rate will be; (2) heating can accelerate the degradation rate, and it is an important factor in UV/PMS system. Acid conditions were more suitable for UV/PMS degradation of Fe~ (2), Co~ (2), NO3-,HCO3- and humic acid in DEHP;4 environment, and also had effect on UV/PMS degradation of DEHP, except humic acid had inhibitory effect on the reaction. Other ions were able to accelerate the degradation rate. (2) the factors affecting the degradation of DEHP in water by ozone were investigated. The results showed that the increase of temperature could accelerate the degradation rate of DEHP by ozone, and the degradation rate of DEHP by ozone was 11:00 at pH. Study on Mechanism and Mechanism of ozonation of DEHP. (3) DEHP degradation process; first, the intermediate products in the degradation process of DEHP were identified, the mass charge ratio was determined, and then Gao Si calculated. The degradation mechanism of DEHP was inferred. The results showed that there were 7 intermediate products and 3 degradation pathways in the process of DEHP degradation by 1UV/PMS. UV/PMS was attacked by HO- radical and directly oxidized. Under the combined action of HO- and SO_4~ (-), HO- was added to the benzene ring of DEHP molecule, and there were 4 intermediate products and 2 degradation pathways in the process of degradation of DEHP by ozone. The main degradation mechanism is the combination of free radical attack on DEHP and direct oxidation, but in ozone system, only HO' attacks benzene ring on DEHP molecule, and no addition reaction occurs.
【学位授予单位】：常州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703

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