Study On The Preparation Of Membranes For Controlling Odor Emitted From Pesticide-polluted Soil And Its Application Effect

The pesticide industry has made great contributions to the healthy development of agriculture in China,but the odor pollutants caused in the pesticide production have also led to many environmental problems.With the implementation of the"two into three"soil policy and the adjustment of industrial structure,pesticide industries have been moved out.The left soil odor pollution has become a key factor affecting the progress of soil pollution remediation and the health of surrounding residents.In order to speed up the remediation progress of pesticide relocation sites,it is urgent to study environmental-friendly materials that can control the escape of odor pollutants from polluted soil.However,there are few research and products in this field at home and abroad,especially in China.In this paper,ethyl acetate(EAC),trichloroethylene(TCE),dimethyl disulfide(DMDS)and p-xylene(PTA)were used as the target pollutants.Natural polymer materials sodium alginate,carboxymethyl cellulose,polyaspartic acid were selected as the main components,and glycerin moisturizing agent,potassium sorbate preservative,polyvinyl alcohol film-forming agent were selected as auxiliary components.After their combination optimization,three hydrogel membranes were prepared.In indoor mini soil column experiments,the hydrogel membrane with the best control effect on soil pesticide odor pollutants was selected,then it was used in-situ experiments on contaminated site.According to the the problems occurred in the application,the components of selected hydrogel membrane was further optimized.Through large-scale soil column experiments,the effects of temperature,pollutant concentration and storage time of membrane solution on the control effects of new hydrogel membrane on odor pollutants were investigated.Moreover,in order to prolong the control time of hydrogel membrane,the bifunctional membranes with hydrogel membrane and microbial membrane were prepared and their effects on controlling odor pollutants were explored.Taking the control rate of the membrane to odor pollutants>85%within 14 days as the evaluation standard,the main results are as follows:(1)Experiment on the selection of hydrogel membrane on controlling soil odor pollutants:Among sodium alginate membrane(SA),sodium alginate carboxymethylcellulose membrane(SC)and sodium alginate carboxymethylcellulose polyaspartic acid membrane(SCP),SCP membrane had the best control effect on ethyl acetate with the highest control rate97.68%.Moreover,SCP membrane had the maximum breaking strength(76.28 MPa)and the lowest vapor transmittance(3.8476 g·mm/m~2·h·k Pa).Therefore,SCP membrane was selected for in-situ test of contaminated site.(2)Experiment in-situ on SCP membrane controlling soil odor pollutants:SCP membrane did not showed good stability,and the control rates for main odor pollutants such as 1-pentene,benzene,styrene,xylene and methyl sulfide was less than target value.This was possibly because hydrogel membrane should have good moisture retention,film-forming compactness and storage stability of membrane solution.In response to these problems,the components of SCP membrane were further optimized to obtain SCPP membrane.(3)Experiment on the effects of SCPP membrane controlling soil odor pollutants:The contrl rates of SCPP membrane for TCE,DMDS and PTA were higher than 85%within 18 days.In terms of influencing factors,environmental temperature has slight effect on the control rate of odor pollutants by SCPP membrane;at low odor concentration(2.0 ml/kg),SCPP membrane showed better control effect.In addition,the storage time of membrane solution has a great impact on the control effect of odor pollutants by SCPP membrane.If the storage time of membrane solution is more than 10days,the control time of odor pollutants by SCPP membrane will be reduced by 28.6%.(4)The environmental friendliness and economic analysis of SCPP membrane showed that SCPP membrane had good biodegradability,and the biodegradation rate was close to 80%at 150 days in soil.SCPP membrane had slight effect on the bacterial community structure in soil,showing good environmental friendliness.The cost of SCPP membrane was far lower than other products with similar functions in the market,showing good application prospect.(5)Experiment on the effects of bifunctional membranes with SCPP and microbial membrane on soil odor pollutants:Microbial membranes formed by PTA degrading bacteria effectively reduced the accumulated PTA concentration under SCPP membrane,and increased control time of SCPP membrane on PTA.At low and high PTA concentration,bifunctional membrane increased control time by 22%and 16%relative to single SCPP membrane respectively,showing good application prospect.