【作者】 冯关涛；

【导师】 刘芃岩；

【作者基本信息】 河北大学 ， 应用化学， 2009， 硕士

【摘要】 酞酸酯类有机物被广泛应用在塑料制品中,特别是在聚氯乙烯(PVC)中占有极高的比例。塑料中的酞酸酯随着时间的推移,可由塑料中迁移到外环境,造成对自然环境的污染。现已证明,在大气、水、自来水厂、土壤和食物中均有酞酸酯类有机物检出。由于酞酸酯在自然环境中残留期较长,生物对酞酸酯有较强的富集作用,一旦进入自然生态系统中,对人类健康带来的危害是无法估计的。因此,越来越多的研究学者将注意力转移到对环境中现存的酞酸酯的降解问题上来。在处理这类污染物的方法中,光催化氧化技术因其简单易行、经济实用、无二次污染的特点,引起学者的普遍关注。以双氧水为氧化剂,高压汞灯作照射光源,对酞酸二甲酯(DMP)的光降解进行了研究。结果表明：DMP在UV/H2O2体系中能很好地降解,其降解速率大于在单一UV辐照下的降解速率,且其降解速率随初始浓度的增大而增大。在pH为中性时,DMP的光降解率大于在酸性或碱性条件下的降解率。在一定H2O2浓度范围内,DMP的光降解速率随H2O2的浓度升高而增大,但当H2O2浓度过高时,其对·OH自由基的清除作用使DMP的光降解速率减慢。浓度为10.0 mg·L-1的DMP在H2O2为20.0 mg·L-1条件下,光照45 min降解率可达90%以上。对DMP及H2O2的初始浓度、光照时间及pH值等因素对降解过程的影响进行了讨论,以期为该方法的实际应用提供必要的基础。为了了解水环境中酞酸酯(PAEs)的降解归趋,对反应机理进行了研究。所测试的三种酞酸酯在水体中的降解过程均符合一级反应动力学。通过气相色谱-质谱联用技术分别对三种物质降解过程中生成的中间体进行了分析,发现3种酞酸酯均从侧链开始降解,光照产生的羟基自由基首先攻击苯环和侧链酯基相连的C-C键,随着C-C键的断裂,酞酸酯被逐步分解为小分子,主要的中间产物为苯甲酸单酯,提出了可能的降解机理。更多还原

【Abstract】 Phthalates are widely used as plasticizers in different resins, especially PVC resins.As a consequence, phthalates are released into the natural environment during manufacture, used, disposal and leaching from plastic materials. Phthalates have been detected in air,natural waters, waterworks, soil and foods.More and more research groups have focused their attention on the degradation of phthalates.Photo catalytic redox reactions used in degrading pollution organics have gained wide interest because of their simplicities, economic advantages and without the second pollution.The photochemical degradation of PAEs (DMP, DEP, DBP) in water was investigated under a variety of reaction conditions using hydrogen peroxide as oxidant. All experiments were conducted under artificial UV light (high pressure Hg lamp).The results showed that DMP was more effectively degraded by UV/H2O2 system than by UV light only and the initial concentration of DMP presented relative effect to the photodegradation rate. The degradation rate of DMP displayed faster in neutral medium than in acid or alkali medium. The rate of degradation of DMP increased when increasing concentration of H2O2,but it decreased at high level of H2O2 because high concentration of H2O2 could remove the-OH in UV/H2O2 system.More than 90% of DMP degraded when a solution of DMP of 10.0 mg·L-1 was radiated under UV for 45 minutes in the presence of hydrogen peroxide of 20.0 mg-L" by the Technology of UV/H2O2. The effects of initial concentration of the phthalates and hydrogen peroxide,the time of UV radiation and pH on the degradation process have been studied in order to provide the necessary basis for practical application of this method.To understand the degradation and the environmental fate of phthalic acid esters in water, the photodegradation process of dimethyl, diethyl and dibutyl phthalates (DMP, DEP, DBP) in an aqueous solution under UV radiation were investigated. The results showed that the degradation of the three tested phthalates follows the first-order kinetics. The degradation intermediates were identified with GC/MS,finded that the chain was degraded firstly,then the Hydroxy free radical which was excited from UV-light, attacked the band of C-C which link the aromatic ring and chain ester group.with the band of C-C disconnect,the PAEs were degraded for small molecule.the primary intermediates was benzoic acid ester.A plausible mechanism was suggested for degradation of these compounds.更多还原