Study On The Determination And Environmental Release Behavior Of Tetrachloroethylene Residues In Dry-cleaned Apparels

For the purpose of maintaining the original appearance and gorgeous colors of upscale clothing,dry-cleaning is frequently adopted in daily life.Tetrachloroethylene?PCE?,a colorless and nonflammable solvent with strong ability of removing greasy dirt,is favored by dry cleaning industry.However,PCE residues in dry-cleaned apparels could cause damage to liver,kidney,central nervous and genital systems,increasing the risk of birth defects and cancer.At present,there is no uniform international standard for the safe concentration of PCE.Therefore,security monitoring is necessary.Meanwhile,in order to break through the international technical barriers,it is necessary to establish an accurate,rapid and effective test method to study PCE residues and environmental release behavior after dry cleaning.The experiment simulated the closed and open environment and studied the influence of temperature,humidity,wind speeds on the PCE release behavior.This study established the mathematical model by experimental data and predicted the safety wearing time to provide the health dressing guide.?1?As PCE is a thermally volatile organics,the choice of extraction method is very important.The experiment developed a new type of supercritical carbon dioxide?SC-CO₂?extraction pretreatment technology and rapid ultrasonic extraction technology,combined with gas chromatography-mass spectrometry?GC-MS?detection method for PCE qualitative and quantitative research.SC-CO₂ extraction technology used dichloromethane as the extract entrainer and the optimum extraction conditions were obtained by using the 3D response surface method?RSM?.The extracts were determined by GC-MS instrument,PCE was characterized by characteristic ions at m/z 94,131,166 and characteristic ions at m/z 166.The PCE retention time was within 5min,it greatly improved the detection efficiency.The simulation extraction rate could reach100.3%.The recoveries of spiked materials ranged from 94.2%to 103.6%with relative standard deviations?RSDs?between 1.67%and 3.78%.The experiment established ultrasonic extraction technology which was simple and convenient.Experiments showed that when the ultrasonic time was 30 min,the ultrasonic temperature was 35?,and the liquor ratio was 1:25?g/m L?,the extraction effect was the best.The recoveries of spiked samples were between 90%and 110%,and the relative standard deviations were within 5%.In the linear range of 0.5¹00?g/mL,the linear correlation coefficient R² of the standard curve of external standard method reached 0.9999.The limit of detection?S/N=3?and the limit of quantitation?S/N=10?were 0.9 mg/kg and 3.0 mg/kg,respectively.?2?The experiment adopted bagged sampling method and cubic environment chamber to simulate the closed environment.The results showed that the release rate of PCE were increased with the temperature increasing,the amount of residues decreased at the same time.And the release rate of PCE were reduced with the humidity increasing,the amount of residues increased at the same time.The confined space had a hindrance to the release of PCE.When the concentration of PCE reached a certain level,PCE showed an equilibrium state of adsorption-release-adsorption.?3?Through the open environment simulation experiment,it was found that the PCE release behavior is a fast descending process under the condition of fixed material and wind speed,which satisfied the negative exponential function and power function morphology.According to the optimized mathematical model,we predicted that PCE residues in the cotton material need more than 66 hours to reach the safety line at annual average wind speed.The amount of PCE residues in the polyester material need release more than a week to reach the safety line under the condition of raising the temperature.PCE residues in the silk only need 1 day to reach the safety standard under the ventilation condition.PCE residues in the wool and mink material required 4to 6 days to reach the safety line in the ventilated environment.Through mathematical modeling,it was found that the wind speed did not dominate the final residual amount of PCE and only accelerated the release rate of PCE.Therefore,the ventilation process needed properly raise the temperature to reduce the final PCE residue.