Studies On The Adsorption And Degradation Of Pentachlorophenol On The Particulate Matter In Water

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.