Research On Environmental Investigation And Assessment Of A Retired Electroplate Plant And Degradation Of P-chlorophenol In Groundwater

This article takes a small retired electroplate site in Tianjin as an example to carry out environmental investigation and risk assessment.Further,for the pollution of chlorine-containing organic compounds in groundwater,using p-chlorophenol（p-CP）as a model pollutant,we report a dechlorination system for the rapid and efficient degradation of p-chlorophenol（p-CP）,in which hydroxylamine hydrochloride（HAH）promotes the activation of sodium percarbonate（SPC）with ferrous ions(Fe²⁺).（1）Environmental investigation and risk assessment of a retired electroplate plantAccording to the technical guidelines for the investigation of soil pollution in construction land and technical guidelines for risk assessment,an environmental survey and risk assessment based on human health and ecological environment were carried out on a small retired electroplate plant in Tianjin.The results showed that none of the soil testing items on the site exceeded the screening value specified in the second category of land in the Soil Environmental Quality Risk Control Standard for Soil Contamination of Development Land;Aluminum,manganese,zinc,and 1,2-dichloroethane in groundwater exceeds Class IV water standard of Standard for groundwater quality,the ratio of detected concentration to screening value is 1.1,15.2,6.5,1.2 respectively;human health risk assessment results show that both carcinogenic and non-carcinogenic risks are acceptable;An ecological risk assessment was conducted by entropy method.The maximum risk entropy of aluminum,manganese,zinc,and 1,2-dichloroethane in the groundwater in the site were 0.74,103.63,183.61,0.31 respectively,which were medium or high risks.It is recommended to carry out remediation or risk control of contaminated groundwater.（2）Enhanced degradation of p-chlorophenol by Fe²⁺-catalyzed percarbonate with hydroxylamine hydrochloride assistedUsing p-chlorophenol as the model of chlorine-containing organic pollutants,we report a dechlorination system for the rapid degradation of p-chlorophenol（p-CP）,in which hydroxylamine hydrochloride（HAH）promotes the activation of sodium percarbonate（SPC）with ferrous ions(Fe²⁺).The effect of the different parameters,including the pH,temperature,concentrations of percarbonate and inorganic ions(Cl^-,SO₄^2-,NO₃^-,Mn²⁺)on the degradation of p-CP was investigated,and the degradation mechanism was analyzed.The results show that the degradation efficiency reached 99%with a HAH:Fe²⁺:SPC:p-CP molar ratio of 5:5:5:1 at 20°C for 5 min.In addition,the oxidation performance of HAH/Fe²⁺/SPC system is not significantly affected by the addition of Cl^-,SO₄^2-or NO₃^-,as well as the reaction temperature.However,too high a concentration of Mn²⁺will inhibit the oxidation performance（the degradation rate drops by about 12%）.Free radical scavenging studies indicate that both HO·and O₂·^-were evidenced to oxidize p-CP in HAH/Fe²⁺/SPC system,while HO·was primarily responsible for the degradation.