【作者】 谢玲玲；

【导师】 周培疆； 吴振斌；

【作者基本信息】 武汉大学 ， 环境科学， 2005， 硕士

【摘要】 五氯苯酚《pentachlorophenol,PCP)作为一种持久性有机污染物已成为全球性的环境污染物之一。鉴于五氯苯酚在水环境中分布的广泛性以及对人类和环境的持久性、高毒性危害,研究其在水环境中的吸附和降解行为具有重要的环境学意义。本论文选择五氯苯酚为研究对象,研究其在水体颗粒物上的吸附和降解行为,并对不同环境因素对吸附的影响以及五氯苯酚与腐殖酸之间的作用机制进行了研究。主要研究工作内容如下: 1.研究了五氯苯酚在东湖底质颗粒物上的吸附行为,并用污染物吸附的热力学方程和动力学方程描述其吸附特性。结果表明,PCP在武汉东湖底质颗粒物上的吸附速度很快,其吸附过程可用二级吸附动力学方程描述。Freundlich吸附等温式可较好地描述PCP在东湖底质颗粒物上的吸附行为。 2.研究了环境因子pH值、盐度、颗粒物浓度、腐殖酸、共存污染物以及表面活性剂存在条件下对五氯苯酚在东湖底质颗粒物上吸附的影响。结果表明,pH值在3-10范围内变化时,PCP在该颗粒物上的吸附量先减小后又缓慢的增加。颗粒物浓度在0.1g·L^-1-2g·L^-1之间变化时,颗粒物对PCP的吸附具有浓度效应。腐殖酸和盐度对PCP在颗粒物上吸附的影响为先促进其吸附量增加,然后趋于缓和。颗粒物高温处理后PCP在东湖底质颗粒物上的吸附量减小。表面活性剂SDS和Tween—80对PCP的吸附均有促进作用,Tween—80对PCP吸附的促进作用较SDS的促进作用要强。由于竞争吸附作用,共存有机物苯酚和六氯代苯均使PCP在东湖底质颗粒物上的吸附量减小,而HCB对PCP在颗粒物上的竞争吸附更强。 3.研究了PCP对腐殖酸作用的荧光猝灭效应,进而说明PCP与腐殖酸之间的作用力及其作用机制。结果表明,腐殖酸可以有效的吸附五氯苯酚分子而使腐殖酸内源荧光发生有规律的猝灭,猝灭机理为静态猝灭。从热力学参数判断,五氯苯酚与腐殖酸之间的作用力主要为氢键和范德华力。 4.研究了PCP在东湖底质颗粒物上的生物降解规律,并着重探讨了颗粒物对生物降解速率的影响。结果表明,PCP在东湖底质颗粒物上的生物降解过程可用准一级反应来描述。PCP在有颗粒物存在下的水体中,其生物降解速率随颗粒物浓度的增加而加快,降解速率与颗粒物浓度的关系可近似用一线性方程表示。颗更多还原

【Abstract】 As a kind of persistent organic pollutants pentachlorophenol (PCP) has become one of the global environmental pollutants. It is very important to study the adsorption and degradation of PCP in water because of its universality in water and its persistent and high toxicity risk to human beings. In this thesis adsorption and degradation of pentachlorophenol on particulate matter in water were studied. Furthermore, the effect of other environmental factors to adsorption of PCP and the interaction mechanism of PCP and humic acid (HA) were also investigated. The main results are as follows:1. The adsorption behavior of PCP on the substrate particulate matter of Donghu Lake was studied, and the equations of adsorption thermodynamics and adsorption kinetics which were often used to describe the adsorption of pollutants in water were applied to describe its adsorption characteristics. The rate of adsorption of the PCP on the substrate particulate matter of Donghu Lake was very fast, and the adsorption kinetics followed second order kinetic model. The Freundlich adsorption models and Langmuir adsorption models were used for the mathematical description of the adsorption equilibrium of the PCP on the substrate particulate matte of Donghu Lake, and the adsorption equilibrium data fitted the Freundlich model very well.2. The influence of the pH value, concentration of the particulate matter, salinity, humic acid, co-existing pollutants and surfactants on the sorption behaviors of PCP on the substrate particulate matter was also studied. With the increase of pH from 3.0-10.0 the adsorption capacity of PCP decreased first and then had a slow increasing. When the particulate matter concentration varied over the range of 0.1g/L to 2g/L, the effect of particulate matter concentration followed the solid concentration effects. The salinity and humic acid could accelerate the adsorption capacity. The adsorption capacity decreased after the particulate matter was dealed with high temperature. Surfactants SDS and Tween-80 had a different promoting effects. Both phenol and hexachlorobenzene decreased the adsorption of PCP because of competitive adsorption.3. The interaction mechanism of pentachlorophenol and humic acid were investigated by studying the fluorescence effect between humic acid andpentachlorophenol. The results shown that the fluorescence of HA was quenched regularly by the pentachlorophenol, and the mechanism of the fluorescence quench was a static quench. Furthermore, the hydrogen bond and Van der Waals force played a main role in the binding of pentachlorophenol with HA on the base of the thermodynamic parameters.4. Biodegradation of PCP and particulate matter interfacial effect were studied. The results proved that biodegradation of PCP followed the pseudo first order equation. The biodegradation rate of PCP increased with the increase of concentration of particulate matter, and the relation between biodegradation rate of PCP and concentration of particulate matter could be expressed by linear equations. An interfacial effect factor was introduced to present the effect of particulate matter on biodegradation rate.5. Adsorption thermodynamics and adsorption kinetics of PCP by Scenedesmus obliguus were studied. The rate of adsorption of the PCP by Scenedesmus obliguus was very fast, and the adsorption percentage of PCP by Scenedesmus obliguus achieved 78%. The adsorption isotherm of PCP by Scenedesmus obliguus could also be described by the Freundlich model. Furthermore, the ultraviolet radiation, concentration of alga, pH value and salinity had effects on the adsorption of PCP.更多还原