| Polycyclic Armatic Hydrocarbons?PAHs?are a kind of persistent organic pollutants?pops?which have the characteristics of high toxicity and difficulty in biodegradation,it is widely existed in a variety of environmental media.The pollution of PAHs in the water environment is becoming more and more serious due to the burning of fossil fuels and the discharge of industrial wastewater.Naphthalene has the highest detection rate in the water environment due to its high water solubility,and it has been listed as a priority for the control of pollutants by US EPA because of it has carcinogenic,teratogenic and mutagenic activities effect.Therefore,this paper takes naphthalene as the target pollutant to study the degradation effect of naphthalene by ozone?O3?,ozone/hydrogen peroxide?O3/H2O2?,ozone/persulfate?O3/K2S2O8,O3/PS?advanced oxidation technology.Single-factor effect experiment are used to investigate the effects of three kind of advantage oxidation technology on degradation of naphthalene in different initial concentration,oxidant additive,pH,temperature ect.,and then analysis the reaction kinetics and reaction mechanism to provide a theoretical basis for engineering practice.The main conclusions obtained are as follows:?1?The single-factor effect experiment found that reducing the initial concentration of naphthalene,increasing the concentration of ozone and increasing the reaction temperature with in the test range all contributed to improving the degradation effect of naphthalene.The addition amount of H2O2 and PS should adjust according to the ozone concentration in O3/H2O2 system and O3/PS system,and the molar ratio of O3 to H2O2 and PS should not be lower than1.4 and 1,respectively.The optimal pH value of naphthalene degraded by O3 system is 7,and the optimal pH value of O3/H2O2system and O3/PS system is 8.With the increase of pH,the degradation rate of naphthalene showed a tendency to increase slowly and then decrease rapidly.?2?The reaction kinetics of naphthalene degradation in O3 system,O3/H2O2 system and O3/PS system were analyzed by low-concentration experiments,and the results showed that the reaction process under different reaction conditions all conform to the second-order reaction kinetics.The results of thermodynamic analysis showed that the activation energy Ea of the three systems for naphthalene degradation was lower than35 kJ·mol-1,and easy to reaction.?3?The results of free radical quenching experiments showed that direct oxidation is the main process of naphthalene degradation in O3 system,O3/H2O2 system and O3/PS system.The degradation of naphthalene in O3 system and O3/H2O2 system was directly oxidized by O3 system when the pH is 3.The degradation rate of naphthalene is increased by about 15%compared with O3 oxidation due to acid activation of K2S2O8can produce SO4-?in O3/PS system.The proportion of free radical indirect oxidation gradually increased with the increase of pH value.The three oxidation technologies that we used can effectively reduce the content of naphthalene.It is hoped that this study can provide some theoretical basis and technical support for the treatment of PAHs pollution. |
PDF Full Text Request