Determination Of Benzene Series And Removal Of Toluene From Laboratory Wastewater

In the inspection departments,scientific institutions,colleges and universities,the production,research,teaching process produce a lot of waste water containing organic matter,heavy metals and strong acid substances.The organic pollution hazards is especially difficult to dispose.But the organic pollution of laboratory wastewater has not yet attracted people's attention.Based on this,the pretreatment technology and determination method of seven kinds of benzene series including toluene,ethylbenzene,p-xylene,m-xylene,o-xylene,1,3,5-trimethylbenzene and 1,2,4-trimethylbenzene were established.And taking toluene as the object,removal of benzene series was studied too.The main research work and achievements were as follows:1.A pretreatment technology was developed for pretreatment of toluene,ethylbenzene,xylene,m-xylene,o-xylene,1,3,5-trimethylbenzene,1,2,4-trimethylbenzene in water samples with ultrasound assisted-emulsification liquid liquid microextraction?USA-ELLME?,which used n-hexane as extractant,acetonitrile as emulsifier.When the volume of sample was 50.00 mL,a good extraction efficiency was obtained by using 150 ?L n-hexane,400 ?L acetonitrile under ultrasonic extraction for 12 min,and the enrichment factor reached 333.2.A new method was developed to determine seven benzene series in water samples by GC-FID coupled with ultrasound assisted-emulsification liquid liquid microextraction?USA-ELLME?.Under the optimized conditions,the mass concentration of the seven benzene series in ranges of 0.08-1.00 ?g/mL had the linear relationships to the peak area with the correlation coefficient >0.998.The method detection limits were ranged from 0.005 to 0.01 ?g/mL.Mixed working solutions of 0.10 ?g/mLfor the seven benzene series were detected by 7 times,RSD were in the range of 1.5%-4.7%.The method had been applied to the test room 437 laboratory wastewater of Chengdu University of Technology and Yan Hu lake,the recoveries of seven benzene series ranged from 86.5% to 110.4%.The determination results met the requirements of trace analysis.3.In order to further reduce the detection limit and improve the sensitivity of the method,an ultrasonic assisted-emulsion liquid-liquid microextraction coupled with gas chromatography-mass spectrometry?USA-ELLME-GC/MS?was used to detect the benzene series.Under the optimized conditions,the mass concentration of the seven benzene series in ranges of 0.5-10 ng/mL had the linear relationships to the peak area with all the correlation coefficient >0.990.The seven benzene series with mass concentration of 1 ng/mL were detected by 5 times,the RSD were in the range of 3.9%-9.9% and method detection limits were ranged from 0.02-0.06 ng/mL.The method had been applied to the test room 311 laboratory wastewater?drug preparation analysis laboratory?of Chengdu University of Technology and Dongfengqu River water.The results showed that the concentration of toluene,ethylbenzene,p-xylene,m-xylene and o-xylene in laboratory wastewater exceeded the national integrated sewage discharge standards.The concentrations of benzene series except for toluene in Dongfengqu River were lower than the national standard.4.Layered magnesium aluminum double hydroxides were prepared using Mg?NO₃?₂·6H₂O and Al?NO3?3·9H₂O as raw materials.With SDS and SDBS as intercalating modifier,Mg/Al-SDS-LDHs and Mg/Al-SDBS-LDHs were prepared by co-precipition method,ion exchange method and roasting recovery method.The effect of preparation conditions?temperature,time,mass of SDS and SDBS?on the adsorption efficiency of toluene were discussed.The results showed that the roasting recovery method was the best.The optimum process of Mg/Al-SDS-LDHs was as follows: the mass of Mg/Al-LDOs was 1.000 g,the dosage of SDS was 0.500 g,the modification temperature is 150°C and the modification time was 1.5 h.The optimum process of Mg/Al-SDBS-LDHs was as follows: the mass of Mg/Al-LDOs was 1.000 g;0.0750 g of SDBS was added and reacted at 150°C for 1 h.At the same time,the saturated adsorption capacity of Mg/Al-LDHs to toluene was about 140 mg/g,and the saturated adsorption capacity of Mg/Al-SDS-LDHs and Mg/Al-SDBS-LDHs on toluene increased to 200 mg/g and 250 mg/g,respectively.5.In order to further study the removal of toluene in wastewater,a model of Mg/Al-SDS-LDHs dosage?y1?and toluene concentration?x1?in wastewater was established: y1=0.0011x14-0.0078x13+0.0242x12+0.0353x1-0.0028,R2=0.9999.The model of Mg/Al-SDBS-LDHs dosage?y2?and toluene concentration?x2?in wastewater was y2=-0.0008x23+0.0068x22+0.0675x2-0.0047,R2=1.At the same time,the treatment effect of actual wastewater containing toluene was very good,using Mg/Al-SDS-LDHs and Mg/Al-SDBS-LDHs according to the theoretical model.The toluene concentration in wastewater were lower to 0.1 ?g/mL of national integrated sewage discharge standards[GB 8978-1996].