土壤与地下水污染防治(soilandgroundwaterpollution课件.ppt

1、國立高雄第一科技大學環境與安全衛生工程系1 Colorimetric test Kits Fiber Optic Chemical Sensors Gas Chromatography Graphite Furnace Atomic Absorption Spectroscopy Immunoassay Infrared Spectroscopy Laser-Induced Fluorescence Mass Spectrometry X-Ray FluorescenceField characterization technologies土壤與地下水污染防治土壤與地下水污染防治(Soil a

2、nd Groundwater Pollution Control)Source:http:/www.epa.gov/ord/SITE/國立高雄第一科技大學環境與安全衛生工程系2Colorimetric test Kits Test kits are self-contained analytical kits that use a chemical reaction that produces color to identify contaminants,both qualitatively and quantitatively.Wide applications-from simple co

3、lorimetric indicator tubes for health and safety monitoring to quantitative testing for definitive site characterization.Also,after the initial site characterization phase to monitor the operating conditions of a remediation system or to confirm that contaminated soils have been removed.國立高雄第一科技大學環境

4、與安全衛生工程系3Advantages Speed Portability Ease of use Low cost per sample國立高雄第一科技大學環境與安全衛生工程系4Some innovative technologiesKit nameContaminatesMedium matrix Range and DL*The Hanby field test kitPetroleum and constituents(gasoline,diesel fuel,jet fuel,crude oil,BTEX,PAHs,PCBsWater and soilSoil 1-1000 mg/k

5、gWater 0.1-20 mg/LThe Clor-N-Oil and Clor-N-Soil KitsPCBsOil,soil,or surface wipe samplesClor-N-Oil kit at 20,50,100,or 500 ppm Aroclor 1242Clor-N-Soil kit at 50 ppm Aroclor 1242The PetroFLAGGasoline,diesel fuel,jet fuel,fuel oil,motor oil,transformer oil,hydraulic fluid,greases,and many other types

6、 of hydrocarbonssoilCommon 20-2000 ppmJet fuel 200-2000 ppmWeathered gasoline 400-2000 ppmThe AccuSensorTCE,total THM(chloroform,bromodichloromethane,chlorodibromomethane,bromoform),BTEX,and PCEWaterTCE 5ppbTHM 10 ppbThe Envifrol Quick Test PCP,TNT,PAHsSoil or water(PCP only)PCP 1.5-90 ppmTNT 3-100

7、ppmPAHs 1-3000 ppmDL=detection limits國立高雄第一科技大學環境與安全衛生工程系5MoreKit nameCosts,US$LimitationsThe deviceThe Hanby field test kit$17/testNot capable of distinguishing different hydrocarbon fractions in mixture samplesThe Clor-N-Oil and Clor-N-Soil KitsNot availableFalse positive due to other chlorinated

8、organicsThe PetroFLAG$10-15/testFalse positive due to natural occurring waxes and oil;good for known hydrocarbonsThe AccuSensor$35/testChloroform would result in the TCE measurement error up to 40%The Envirol Quick Test$40/testTCP,TeCP can interference the results國立高雄第一科技大學環境與安全衛生工程系6Mode of operati

9、on I Hanby Field test kit(petroleum)weighing five grams of soil sample,placing it into a beaker,adding an ampoule of solvent to the soil,and stirring the sample for approximately two minutes to extract the contaminant.The extract then is poured from the beaker into a marked test tube,and the catalys

10、t is added to the test tube.The mixture is shaken for two minutes while the color change develops.The developed color of the precipitate is compared with a calibration photograph to obtain quantitative results.The water test is performed in the same manner,with the exception that a 500-milliliter(ml

11、)water sample is extracted with solvent in a 500 ml separatory funnel,which is included in the water test kit.The procedure takes approximately 10 minutes Dexsil Clor-N-Oil and Clor-N-Soil kit(PCBs)Several grams of sample are introduced into a vial that contains an ampoule of organic solvent,and the

12、 PCBs are extracted from the sample medium with the solvent.The extract is treated with metallic sodium to strip chlorine from the biphenyl compound as chloride ions.An acidic buffer is added to the extract to quench any unreacted sodium and to transfer the chloride ions into the aqueous phase.Final

13、ly,chloride ions are measured colorimetrically by an indicator solution that creates a purple or yellow color depending on the presence of chloride ions.The purple color indicates the absence of chloride,and therefore the absence of PCBs,in the sample.A yellow or clear color indicates the presence o

14、f chloride,and therefore the presence of PCBs,in the sample.The procedure takes approximately 10 to 15 minutes.國立高雄第一科技大學環境與安全衛生工程系7Example-Hanby kit in screening TPHs in soil 國立高雄第一科技大學環境與安全衛生工程系8Mode of operation II PetroFLAG(hydrocarbons)weighing 10 grams of soil by an electronic balance,placing

15、the soil sample in a test tube,adding extraction solvent to the tube,shaking the tube intermittently for four minutes,filtering the extract into a vial that contains development solution,and allowing the solution to react for 10 minutes.The filtration step is important because the analyzer measures

16、the turbidity or optical density of the final solution.Approximately 25 samples can be analyzed per hour.The vial of developed solution is placed in the meter,and the instrument produces a quantitative reading that reveals the concentration of hydrocarbons in the soil sample.AccuSensor(TCE/THM)a wat

17、er sample is poured into a standard 40-ml volatile organic analysis(VOA)vial with an AccuSensor cap that has a Teflon membrane.The vial is shaken for 30 seconds to allow volatile compounds to partition into the headspace of the vial and reach equilibrium.The vial is inserted cap-first into the meter

18、,exposing the gas phase in the headspace to the porous Teflon membrane.The volatile analytes in the headspace permeate the membrane and then encounter the reagent.The degree of absorbency is measured and the concentration is displayed in parts per billion(ppb).The concentration in the headspace,diff

19、usion rate of the analyte,and reaction kinetics all are dependent on temperature.The AccuSensor meter incorporates a thermistor and software that provide automatic temperature compensation within an operating range of 0 to 50 degrees Centigrade.The procedure takes approximately five minutes.國立高雄第一科技

20、大學環境與安全衛生工程系9Mode of operation III Envirol Quick Test(PCP)The Envirol Quick Test uses a photochemical reaction to produce a color proportional to the concentration of the analyte of interest.A small portable photometer called the Envirometer is used to measure the reaction.Three standards provided w

21、ith each test kit are used to calibrate the Envirometer.The standard curve for the photochemical reaction is stored electronically in the unit.A calibration verification solution,also provided with each test kit,is used to verify the calibration curve.A soil sample is weighed,extracted with a solven

22、t,and then filtered.The single analyte test system entails using an organic solvent to extract the analytes from soil and employs various combinations of solid phase extraction(SPE),liquid-liquid extraction,and acid-base cleanup techniques to separate the analytes into an organic solvent.The extract

23、ion procedure used varies according to the specific test to be performed.Filtration helps to reduce interferences.The sample is placed in the Envirometer and the degree of absorbency of the sample is measured and converted into a concentration of PCP,trinitrotoluene(TNT),or carcinogenic PAHs.The ent

24、ire extraction and analysis procedure requires approximately 20 to 30 minutes.國立高雄第一科技大學環境與安全衛生工程系10Fiber Optic Chemical Sensors(FOCS)國立高雄第一科技大學環境與安全衛生工程系11Typical usages FOCS have primarily been developed to measure volatile petroleum constituents such as BTEX and chlorinated VOCs such as TCE,PCE,a

25、nd carbon tetrachloride in water,air,or soil gas.The sensors have been developed to be placed down monitoring wells to provide in situ measurements of VOC concentrations in groundwater.FOCS typically measure total VOC concentrations and are not capable of distinguishing individual volatile organic c

26、hemicals.With appropriate chemically selective layers,FOCS are capable of measuring SVOCs as well.國立高雄第一科技大學環境與安全衛生工程系12Mode of operationLight is transmitted into the optical fiber from a light emitting diode(LED)and detected at the opposite end by a photodiode detector.A reference detector monitors

27、 the LED output and compensates for light source fluctuations.The amount of light transmitted to the detector is dependent upon the difference in refractive index of the optical fiber core and the chemical coating.When the probe is immersed into water containing VOCs,the VOCs partition into the orga

28、nophilic coating and change the effective refractive index of the coating allowing light to escape from the optical fiber.The resultant loss of light reaching the detector correlates to the concentration of VOCs present.國立高雄第一科技大學環境與安全衛生工程系13Advantages The design of intrinsic FOCS provides in situ a

29、nd real time monitoring.FOCS are small in size due to small fiber optic diameters.Optical fibers are flexible within limits allowing greater access to difficult locations.Transmission over long distances allow monitoring in deep wells and provide a measure of safety for monitoring of hazardous atmos

30、pheres.Multi-element analysis is possible using various fibers and a single central unit.國立高雄第一科技大學環境與安全衛生工程系14Performance specifications Detection Limits Typical detection limits are around 1 ppm for VOCs in water.Lower detection limits are possible with pre-concentration of the analyte.Calibration

31、 Calibration consists of measuring the response of the detector to a calibration standard.Calibration standards should consist of a series of known analyte concentrations in a representative sample matrix.Detector response is plotted against analyte concentration to generate a calibration curve.As w

32、ith most modern instrumentation,calibration and data acquisition is controlled and recorded with a microprocessor.Sample Preparation FOCS are typically used for in situ measurements precluding sample preparation.國立高雄第一科技大學環境與安全衛生工程系15LimitationsMany FOCS are not compound specific and will react to m

33、any VOCs and will produce a reading only for the concentration of total VOCs.The detection limits can be high compared with conventional analytical methods such as gas chromatography.FOCS are mainly used to detect gross contamination.Some sensors are temperature and time dependent.A temperature sens

34、or can be added to the probe containing the FOCS to compensate for changes in temperature.Because sensor response is based on diffusion,the measured concentration may vary with time that the FOCS is in contact with the target analyte.Therefore,it is critical that equilibrium be achieved before a mea

35、surement is taken.Most FOCS reach equilibrium in 5 to 10 minutes which is indicated by a steady state signal.The number of reversible reactions,that is adsorption and subsequent desorption,is limited,so probes may have to be regenerated after extended use.Dynamic ranges are usually lower than tradit

36、ional electrodes which means that either the sample must be diluted or the sensor recalibrated.國立高雄第一科技大學環境與安全衛生工程系16Gas Chromatography Function of each part國立高雄第一科技大學環境與安全衛生工程系17Typical uses Gas chromatography(GC)analysis is a widely used technique for field-based analysis.Analysis of organic compo

37、unds is possible for a variety of matrices such as water,soil,soil gas,and ambient air.Typical settings include:Site characterization Stationary source testing and monitoring Hazardous waste sites for determining personal protective equipment(PPE)level Fence line monitoring during removal or remedia

38、tion activities Emergency response testing 國立高雄第一科技大學環境與安全衛生工程系18Commonly seen SW 846 methods need GC Phenols Method 8041(GC-FID or ECD)Phthalates Method 8061A(GC-ECD)Amines Method 8070A(GC-NPD)Chlorinated pesticides Method 8081A(GC-ECD)PCBs Method 8082(GC-ECD)PAHs Method 8100(GC-FID)Chlorinated hyd

39、rocarbons Method 8121(GC-ECD)Volatile organic chemicals(VOC)Method 8240 Organophosphorus compounds Method 8141A(GC-NPD or FPD)Chlorinated herbicides Method 8151A(GC-ECD)MTBE Method 8260(GC/MS)Halogenated VOC Method 8260B SVOCs/base neutral acids(BNA)Method 8270C(GC/MS)Dioxin Method 8280(GC/MS)國立高雄第一

40、科技大學環境與安全衛生工程系19Separation factorsStationary phase-An organic liquid compound that is either coated on or covalently bonded to the silica surface of a capillary column.Stationary phases are occasionally solids packed inside the column.The most widely used columns are the fused silica capillary colum

41、ns due to strength and flexibility.The polarities of the compounds of interest dictate the choice of stationary phase,under the rule like dissolves like.Commonly used stationary phases include:(1)polydimethyl siloxane(referred to as OV-1 of SE-30)for PCB or PAH;(2)carbowax used for free acids,alcoho

42、ls,and glycols;(3)OV-17-for pesticides and glycols;(4)OV-210-for chlorinated aromatics,nitroaromatics,and alkyl substituted benzenes;(5)OV-3 or SE-52 for halogenated organics.Carrier gas-The mobile phase is composed of an inert carrier gas,usually nitrogen,helium,or hydrogen.The choice of carrier ga

43、s is frequently determined by the type of detector used and subsequent purity requirements.The sample constituents are transformed into the gaseous phase and are carried along the column during separation.By increasing the speed(flow rate)of the carrier gas,the analysis time can be reduced;however,o

44、ptimal resolution may be compromised.A faster flow rate also sweeps the injector more efficiently,improving introduction of the sample into the column.If resolution is not compromised,increased flow rates can also reduce analysis times.Length-Capillary columns vary in length from 15 to 100 meters is

45、 a coiled configuration to fit in the instrument oven.For environmental analysis,30-to 60-meter columns typically are used.Shortening the length of the column can shorten the analysis time;however,resolution(separation)will be compromised.Again,if resolution is not compromised,analysis time can be r

46、educed with a shorter column.Diameter-Diameters of open tubular capillary columns are typically between 0.32 and 0.25 millimeter,with high resolution columns having diameters of 0.20 to 0.15 millimeter.The smaller diameter columns require special injection splitting to reduce the sample size and pre

47、vent column overload.Columns referred to as mega bore open tube columns are also available and have a greater capacity but at the expense of resolution.However,these columns have better resolution than packed columns.Packed columns have diameters large as 2 millimeters.The smaller diameter produces

48、better resolution and greater selectivity,but can handle only a small volume of sample(1 to 2 microliters).Column bleed-Another problem is column bleed.This phenomenon is best described as the elution of the stationary phase.A frequent cause of column bleed is excessive oven temperature.The end resu

49、lt of column bleed is a fouled detector.More sensitive detectors such ac electron capture detectors are highly susceptible to column bleed.國立高雄第一科技大學環境與安全衛生工程系20Photoionization Detector A photoionization detector(PID)consists of a special ultraviolet lamp,ranging in energy from 9.5 to 11.7 eV,mounte

50、d on a low-volume flow-through cell.As constituents of the sample pass through the cell,they are energized and ionized.The ions are collected at positively charged electrodes,where the change in current is measured.The 10.2 eV lamp emits ultraviolet light at 121 nanometers(nm),which is sufficient to