Comparing And Choosing On Pretreatment Method Of The Determination To Typical Organic Substances In Solid Waste

Over the last decade,as the rapid growth of economic,people's living standards are improving,at the same time,it brings a large amount of solid waste,different industry produce different solid waste,the species of substance they contain have huge difference,so the way of treatment and disposal are not the same,if it is ordinary solid waste,we disposed it by the ordinary way,but if it is special solid waste,according to the national requirements,it must go through special treatment in order to reducing pollution to environment,and protecting people's health,so before disposaling the solid waste,it must conducts a risk identification.Identifying whether the solid waste is hazardous solid waste,we do it from the following characteristics,the first,whether it have corrosive.The second,whether it have acute toxicity.The third,whether it have leaching toxic.The fourth,whether it have flammable.The fifth,whether the content of toxic substances is exceeded,the way of identify is determining the content of substances directly,if the content of one or more substances is exceeded,then identified it as a hazardous waste.If the solid waste has one or more of the five characteristics,then results of identification is hazardous waste,so the ordinary solid waste and hazardous solid waste must be treated differently.In this dissertation,we studied by the content of toxic substances in the identification of hazardous solid waste,to the pre-treatment process of determining the content of organic toxic substances,conducting a research in-depth,the extraction of organic toxic substances from solid waste,the purification of sample solution after extraction,the concentrate of sample solution before measured,based on laboratory conditions and comparing the effect of several different extraction methods,several different cleaning methods,several different concentrate method,results were compared under different methods.With the natural soil instead of solid waste,toxic substances adding the following organic toxic substances as a certain concentration to the soil,organophosphorus compounds,organochlorine compounds,PCBs,chlorinated hydrocarbon compounds,they are often be determined in the identification of hazardous solid waste,the representative compounds are methyl parathion,omethoate,?-HCH,?-HCH,?-HCH,?-HCH,aldrin,heptachlor,heptachlor biphenyls,hexachlorobenzene and a total of ten kinds of substances,using different extraction methods,different purification methods,different concentration methods,while changing the relevant conditions,determining the recoveries.the results following:?1?Using the extraction way of accelerated solvent extraction,ultrasonic extraction,mechanical vibration extraction,extracting 10 kinds of organic toxic substances from soil,the results show:the way of accelerated solvent extraction have the best effect,and the recoveries is high of all,at the same time,the reproducibility its data is best,the average recoveries and relative marked deviations were 92.2%and 6.06%,followed is the ultrasonic extraction way,the extraction of mechanical shock has the worst effects,the average recoveries were 85.9%and 79.5%,useing the different single solvent and mixed solvent to extract,and found the mix solvent acetone/hexane?1:1?is the best extraction solvent.Each extraction way have the most appropriate extraction time,the time of accelerated solvent extraction is static extracting 9min,the time of ultrasonic extraction is twice every 30min a total of 60min,the time of mechanical shock extraction is twice 45min total 90min.The optimum extraction temperature of accelerated solvent extraction is 80?.?2?After the sample being extracted,using solid phase extraction column and concentrated sulfuric acid to purify the sample liquid,through the experiment,we found the effect of Florisil?Florey diatomite?packing and C₁₈ silica gel column in three solid-phase extraction column is better,but the effect of HLB column is general,and the effect of using the concentrated sulfuric acid to purify is is good too,the only problem is that some of substances have the acid-labile,as the result,the purification effect is not well,by the comparing recoveries,applicability and practicality factor,solid phase extraction column purification is the best way.?3?Before determining,using the way of nitrogen blowing and rotary evaporation concentrate the sample solution,the results showed:the average recoveries were 98.9%and 94.3%.and the relative standard deviations were 3.2%and 5.0%,the effect of the concentrate way by rotary evaporation is a litter better,through studying we know both concentrate way have their own characteristics,nitrogen blowing suit for small volume of concentrated sample and deal with more number of samples,but spending m ore time,to the way of rotary evaporation is suit for a large sample volume and spending less time,However,it loss more and easy cross-contamination.?4?Conclusions:To the study of the ten kinds of of organic toxic substance,the best extraction way is the way of accelerated solvent extraction,the temperature of extraction is 80°C,the time of extraction is 9min?the solvent of extraction is acetone/hexane?1:1?.The best purify way is using the solid-phase extraction column of Florisil or C₁₈.The best concentrate way is using the way of nitrogen blowing,the temperature is 45 °C.The results of this dissertation will provide basic data and basic experience for the pretreatment method of determining the content of toxic substances in hazardous solid waste,and provide a scientific basis for the way of identifying hazardous solid waste.