胡敏酸胶体对渭河沉积物中PPCPs的解吸行为影响研究

发布时间：2018-04-09 15:39

本文选题：沉积物　切入点：PPCPs　出处：《长安大学》2015年硕士论文

【摘要】：药品及个人护理用品(简称PPCPs)是一类新型微量有机污染物,以抗生素和解热镇痛药类物质检出频率较高,由于一些物质可以导致“三致效应”,所以已成为危险污染物质的研究热点。河床沉积物是运移溶质的重要介质,其对污染物的吸附/解吸行为直接影响污染物的迁移特征。吸附过程将污染物从河流中吸入沉积物中,使沉积物受到一定程度的污染,还有可能造成二次污染;解吸过程则是将沉积物中的污染物释放出来,使这些被解吸出来的污染物在大量河水中得到稀释,降低污染程度,且沉积物的污染程度也得到相应的缓解。渭河作为黄河第一大支流及渭北平原上最为重要的河流,有学者对渭河沉积物中的氟苯尼考、多环芳烃、有机氯农药、土霉素和对乙酰氨基酚等有机污染物的吸附行为进行了广泛的研究,但对渭河沉积物中土霉素和对乙酰氨基酚的解吸行为还没有提出一定的见解。因此,研究PPCPs类物质在渭河沉积物中的解吸行为对于进一步了解其在渭河流域的迁移、转化、归趋是极为重要的,对有效防治渭河流域PPCPs类物质的污染,保障地表地下水的安全提供了理论依据和借鉴。本文选择渭河陕西段中游有诸多农家乐及养殖业等PPCPs污染源的区域为典型研究区,以抗生素中土霉素(OTC)和解热镇痛类药物中的对乙酰氨基酚(APAP)作为目标性污染物,从有无胡敏酸胶体存在的角度,通过批量平衡法系统的研究了渭河河床沉积物中这两种目标污染物的解吸动力学和热力学的特征,探讨了目标污染物在渭河河床沉积物上的解吸模式及机理。通过研究得到如下认识:1.渭河河床沉积物中OTC和APAP的解吸过程通过20min基本上达到平衡,符合准二级动力学模型。不同温度对OTC和APAP的解吸行为有显著的影响,升高温度对解吸过程均表现为抑制效应。2.渭河河床沉积物中OTC和APAP的解吸过程是自发的放热反应,也是解吸后固液界面混乱度增加的熵增过程。3.离子强度的升高对渭河河床沉积物中OTC和APAP的解吸过程表现为抑制效应。4.渭河沉积物中OTC和APAP的解吸趋势相似,但解吸规律有一定差异,这可能与两者的内部结构(如官能团等)有关。5.胡敏酸胶体存在下,渭河沉积物中OTC和APAP的解吸平衡时间向后延迟,在30min时基本达到平衡状态。解吸动力学模型也符合准二级动力学模型;升高温度不利于解吸过程的进行。6.胡敏酸胶体对渭河沉积物中OTC和APAP的解吸行为有明显抑制作用,延迟了解吸平衡时间并且使解吸量明显降低。
[Abstract]:Pharmaceutical and personal care products (PPCPs) are a new kind of trace organic pollutants, which are detected frequently by antibiotics and antipyretic analgesics, because some substances can cause "three effects".Therefore, it has become a hot spot in the research of hazardous pollutants.River bed sediment is an important medium for solute transport, and its adsorption / desorption behavior directly affects the transport characteristics of pollutants.In the process of adsorption, pollutants are inhaled from the sediment from the river, causing the sediment to be polluted to a certain extent, and the secondary pollution may be caused; the desorption process is the release of the pollutants from the sediment.These desorbed pollutants were diluted in a large amount of river water to reduce the degree of pollution, and the pollution degree of sediment was alleviated accordingly.As the largest tributary of the Yellow River and the most important river in the Weibei Plain, some scholars have studied the flufenicol, polycyclic aromatic hydrocarbons, organochlorine pesticides in the sediments of the Weihe River.The adsorption behavior of oxytetracycline and paracetamol and other organic pollutants has been extensively studied, but the desorption behavior of oxytetracycline and paracetamol in the sediment of Weihe River has not been discussed.Therefore, it is very important to study the desorption behavior of PPCPs in the sediment of Weihe River in order to further understand its migration, transformation and fate in Weihe River Basin, and to prevent and control the pollution of PPCPs in Weihe River Basin effectively.It provides theoretical basis and reference to ensure the safety of surface groundwater.In this paper, the typical area of PPCPs pollution sources such as Nongjiale and aquaculture in the middle reaches of the Weihe River was selected as the typical research area, and oxytetracycline (OTC) in antibiotics and paracetamol in antipyretic and analgesic drugs were used as the target pollutants.The desorption kinetics and thermodynamics of these two target pollutants in the sediment of Weihe River bed were systematically studied by batch equilibrium method from the point of view of the presence of Hu Min acid colloid.The desorption model and mechanism of target pollutants on the sediment of Weihe River bed are discussed.Through the study, we can get the following understanding: 1.The desorption process of OTC and APAP in the sediment of Weihe River bed is basically balanced by 20min, which accords with the quasi-second-order kinetic model.The desorption behavior of OTC and APAP was significantly affected by different temperatures, and the inhibition effect of increasing temperature on the desorption process was found to be. 2. 2.The desorption process of OTC and APAP in the sediment of Weihe River bed is a spontaneous exothermic reaction, and it is also a entropy increasing process of increasing the degree of chaos at the solid-liquid interface after desorption.The desorption of OTC and APAP in the sediment of Weihe River bed was inhibited by the increase of ionic strength.The desorption trend of OTC and APAP in Weihe River sediment is similar, but the desorption law is different, which may be related to their internal structure (such as functional groups).In the presence of Hu Min acid colloid, the desorption equilibrium time of OTC and APAP in the sediment of Weihe River was delayed backward and reached the equilibrium state at 30min.The desorption kinetic model also accords with the quasi-second-order kinetic model, and the increase of temperature is not conducive to the desorption process.Hu Min acid colloid inhibited the desorption behavior of OTC and APAP in the sediment of Weihe River, delayed the desorption equilibrium time and decreased the desorption amount.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X522

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