Extraction And Analysis Of Pcbs In Soil And Effect Of Lignin On Adsorption Behavior Of PCBs

Polychlorinated biphenyls?PCBs?are a type of persistent organic pollutants.PCBs in the environment can pose potential hazards and risks to human health.At present,PCBs pollution in C hina is mostly concentrated in sediments in the coastal areas and in the soil around the e-waste dismantling base.The overall pollution level is low,but the pollution in some areas is quite serious.As an important environmental medium,soil collects a large number of pollutants such as PCBs.Because of the stability of the chemical structure and properties of PCBs,residual PCBs in soil are extremely difficult to be biodegraded and chemically decomposed.Increasing the solubility and bioavailability of PC Bs can greatly promote the chemical repair and bioremediation of PCBs in soil.Analyzing the adsorption behavior of PC Bs in soil can provide data support and theoretical basis for soil remediation work,and it is the precondition for soil remediation.This work first established an improved Q uEC hERS rapid extraction-gas chromatography-mass spectrometry method for the determination of PC Bs in soil.Using this analytical method as a means,based on the surface activity of potassium lignosulphonate?KLS?,the adsorption of PCBs on soil by KLS was studied.Impact.?1?Established a method to improve the extraction and analysis of 16 types of phthalic acid esters?PAEs?in soil by QuEC hERS.The Q uEChERS extraction method is mainly applied to the detection of pesticides in food.When applied to the extraction and analysis of organic pollutants in soil,the following improveme nts have been made:Increase the moisture content of soil samples;Ultrasound-assisted extraction is used instead of the traditional manual shaking extraction method to make the extraction more efficient;use dichloromethane?DCM?/n-hexane?v:v=1:1?and Alkane/acetone?v:v=1:1?was used as the extractant instead of acetonitrile,and C18/N-propylethylenediamine?PSA??m:m=1:1?was used as the scavenger.Methods The PAEs in soil were analyzed with the recoveries of70.00%-117.90%and relative standard deviations?RSDs?of 0.67%-4.62%,which satisfied the analysis requirements.?2?The Q uEC hERS method was used to extract and analyze seven kinds of PCBs in soil by using ionic liquid 1-butyl-3-methylimidazolium bis?trifluoromethanesulfonyl?imide?[BMIm][NTf₂]?.The results showed that adding[BMIm][NTf₂]to the extraction solvent n-hexane/acetone?v:v=1:1?can significantly improve the extraction efficiency,and the recovery rate of 6 kinds of PC Bs in the soil can reach 84.00%-113.50%.RSD was1.35%-4.46%,while the recovery of PCBs was 68.70%-97.10%without[BMIm][NTf₂]addition.At the same time,the addition of ionic liquid[BMIm][N Tf₂]could reduce the matrix effect to 1.74%-8.79%.?3?KLS was characterized by gel permeation chromatography?GPC?,infrared?IR?,ultraviolet?UV?,and surface tension.The molecular weight of KLS is relatively large,the number average molecular weight and the average molecular weight are higher than 100,000;compared with humic acid,K LS has slightly lower carbon and nitrogen content,higher oxygen content,carbon to nitrogen ratio of 11.15-12.72,and humic acid.The class is much smaller;the structure contains a large number of oxygen-containing groups such as hydroxyl groups;its critical micelle concentration is about 3.0 g/L.?4?We studied the effect of KLS on soil adsorption PCBs.The results showed that the KLS with larger molecular weight had a more obvious effect on soil adsorption of PCBs,which could significantly increase the solubility and bioavailability of PCBs.Whe n the addition amount was 3%,it could significantly inhibit the adsorption of PCBs on the soil.Saturated adsorption capacity decreased,and the saturated adsorption capacity of PCB28,PCB101,and PCB153 decreased by 36.07%,22.68%,and 9.29%,respectively.The adsorption process of PC Bs in soil after K LS addition accords with the pseudo-second-order kinetics,mainly based on chemical adsorption;the isothermal adsorption process of PCBs on soil accords with the Freundlich model and belongs to the heterogeneous surface adsorption.