CEE 697z Organic Compounds in Water and Wastewater

Transcription

1 Print version CEE 697z Organic Compounds in Water and Wastewater PCBs and other HOCs: Voatiization & other processes Lecture #36 Voatiization: The two fim theory p g Competey mixed Stagnant poor mass transfer p i Stagnant poor mass transfer c i Interface c Competey mixed 1

2 Two fim mode Universa Gas Law n V P RT a Fux from the bu iquid to the interface J K ( c c ) i Fux from the interface to the bu gas Moar concentration Mass transfer veocities (m/d) J g Kg ( RT p p g i) a And the K s are reated to the moecuar diffusion coefficients by: K D z D g Kg z g Two fim theory (cont.) We want to be abe to reate fux to bu air and water concentrations interface concentrations cannot be directy measured p J v v H g c to do this we must substitute expressions for the interface concentrations e 2

3 Air/Water Equiibrium Henry s Law or Whitman s 2 fim mode (cont.) According to Henry s aw: And reating this bac to the bu concentration Reca: J K ( c c ) p H J K c i e now soving and equating the fuxes, we get (pg. 371 in text): 1 1 RTa v K HK The net transfer veocity across the air-water interface (m/d) sometimes represented as K o v p H c i e i So: e i J ci c K g 3

4 correction (atm m 3 gmo -1 ) Figure 20.4, page 373 in text. Two Fim Voatiization Mode Jeremiason s equation vo K h o f w Same as Chapra s v vv H f 1 d1 Where: 1 K o RT H a 1 w 4

5 Estimating 2-fim parameters The gas fim coefficient, 02. u aho The iquid fim coefficient apcb, aho, 2 D D PCB, air HOair, wco, u 2 10 Kinetic viscosity: moecuar diffusivity Schmidt Number 164 wpcb, wco, 2 Sc Sc PCB CO Effect of U w and H e Chapra, pg

6 Bamford, H.A., Poster, D.L. and Baer, J.E. (1999) Temperature dependence of Henry's aw constants of thirteen poycycic aromatic hydrocarbons between 4 degrees C and 31 degrees C. Environmenta Toxicoogy and Chemistry 18(9), Determination of H e The gas-stripping device: a 122- cm by 15.2-cm diameter gass reactor, a 5-mm gass impactor, a 5-μm pore-size air stone, and a 500-m gass gas washing botte. Procedure: The apparatus was fied to a depth of 83 cm with 10 L of deionized water. Between 130 m/min to 200 m/min of compressed air was passed through a hydrocarbon trap to remove possibe contaminants and through a gas washing botte to saturate the air with water vapor prior to entering the reactor through the air stone mounted at the bottom of the water coumn. Bamford, H.A., Poster, D.L. and Baer, J.E. (1999) Temperature dependence of Henry's aw constants of thirteen poycycic aromatic hydrocarbons between 4 degrees C and 31 degrees C. Environmenta Toxicoogy and Chemistry 18(9), Det. of H e (cont.) Procedure (cont.): Air exiting the reactor passed through the impactor to remove aerosos created by breaing bubbes, then through a cyindrica poyurethane foam pug (PUF) housed in a gass coumn to capture vapor-phase compounds. The efficiency and appication of PUF to absorb hydrophobic organic contaminants (HOCs) have been evauated in severa studies Water sampes (50 m) were drawn through a Tefon stopcoc ocated at the base of the reactor. During each experiment, simutaneous air and water sampes were coected every 24 to 48 h for 6 to 12 d. 6

7 Det. of H e (cont.) with QC The entire system was ocated in a controed environment room, where the ights remained off during each experiment to minimize any oss of compounds to photodegradation. Compound mass baances were determined to insure anaytes were not ost to degradation or to eas in the system Mass recoveries for the compounds ranged between 85% and 112% of the initia mass added. Bamford, H.A., Poster, D.L. and Baer, J.E. (1999) Temperature dependence of Henry's aw constants of thirteen poycycic aromatic hydrocarbons between 4 degrees C and 31 degrees C. Environmenta Toxicoogy and Chemistry 18(9), Bamford, H.A., Poster, D.L. and Baer, J.E. (1999) Temperature dependence of Henry's aw constants of thirteen poycycic aromatic hydrocarbons between 4 degrees C and 31 degrees C. Environmenta Toxicoogy and Chemistry 18(9), Det. of H e - Chemica Anaysis Extraction: The PUF sampes were Soxhet extracted for 24 h with 150 m of chromatographic grade petroeum ether. Extracts were reduced to <3 m by rotary evaporation, switched to hexane, and further concentrated under a gente stream of cean N 2 to a fina voume of 1 m. Each water sampe was sovent extracted three times with 10 m of hexane in a separatory funne, and combined extracts were dried with Na 2 SO 4 and reduced by rotary evaporation to 1 m in hexane. The concentrated sampes were transferred to amber autosamper vias and seaed with Tefon caps and stored in the dar at 4 C unti anaysis. Anaysis: A compounds were anayzed by GC/MS (HP 5890 GC and HP 5972 Mass Seective Detector) operated in seective ion monitoring (SIM) mode. The coumn was 30 m in ength, 0.25 mm i.d. with a cross ined 5% pheny-methy siicone fim thicness of 0.25 μm. Identification of individua compounds was based on the retention times of the parent ion of each compound reative to the retention time of a caibration standard. Interna standards, consisting of deuterated compounds were added to the caibration standard and each sampe prior to GC/MS anaysis. Interna standards were used to cacuate reative response factors for each anayte by comparing a nown mass of anayte in the caibration standard to the nown mass of a particuar interna standard. 7

8 Det. of H e - Resuts sss Voatiization vs overa oss rate (/yr) Log Kow (yr-1) vo (yr-1) -regr. vo-regr. 8

9 Expicity reported pathways (dashed ines) and pathways added to dechorination process M through the cassification tree anaysis (soid ines). Note that the numbers are arranged by homoogue and correspond to congener structures assigned in the origina wor of Baschmiter and Ze (47) with corrections to congener numbers by Schute and Maisch (48) and corrections to numbers by Guitart et a. (49) (0 represents bipheny). Hughes, A.S., Vanbriesen, J.M. and Sma, M.J. (2009) Identification of Structura Properties Associated with Poychorinated Bipheny Dechorination Processes. Environmenta Science & Technoogy 44(8), CEE 697z - Lecture #36 PCB Mass Baance in Lae Superior, 1986 Atmospheric Deposition Wet 125 g/yr Dry 32 g/yr Atmosphere ~200 g Net Voatiization ~1900 g/yr Other discharges ~40 g/yr Rivers ~110 g/yr Partice Setting ~3000 g/yr Outfow ~60 g/yr Water Coumn ~10,100 g Sediment ~4900 g Recycing ~2890 g/yr Buria ~110 g/yr 9

10 PCBs in the Lae Superior Reference: PCBs in Lae Superior, : Decrease in Water Concentrations Refect Loss by Voatiization, by Jeremiason, Hornbuce and Eisenreich, Environmenta Science and Technoogy, 28:903 (1994) St. Mary s River Fu 1, 2 or 3-d mechanistic mode Combine with advective fow Water (1) Diffusion (v d ) Setting (v s ) Mixed Sediments (2) Deep Sediments (3) Resuspension (v r ) Buria (v b ) 10

11 Summary of sorption & voatiization effects Assume T a =283 K M=200 g/moe U w = 5 mph v s =91 m/yr Assimiation refers to genera rate of remova Summary: pesticides Chapra, pg

12 Summary: PCBs Chapra, pg.736 Summary: PAHs Chapra, pg

13 Concusions on PCB fate The environmenta fate and transport of PCBs is argey governed by their physica-chemica characteristics, properties which vary considerabe across the spectrum of species incuded in this famiy of chemicas. Chief among these properties are the octano-water partition coefficient, a measure of the potentia to associate with partices, and the Henry s Law constant, a refection of the partitioning of the chemica between air and water. In genera, high MW PCBs are strongy associated with partices and ow MW PCBs are more strongy partitioned to the atmosphere. As a resut, fish consumption advisories are common in Michigan and other states. Prediction of partition coefficients for compex environmenta contaminants: Vaidation of COSMOtherm, ABSOLV, and SPARC Stenze, A., Goss, K.U. and Endo, S. (2014) Prediction of Partition Coefficients for Compex Environmenta Contaminants: Vaidation of COSMOTHERM, ABSOLV, and SPARC. Environmenta Toxicoogy and Chemistry 33(7),

14 Prediction of partition coefficients for compex environmenta contaminants: Vaidation of COSMOtherm, ABSOLV, and SPARC Stenze, A., Goss, K.U. and Endo, S. (2014) Prediction of Partition Coefficients for Compex Environmenta Contaminants: Vaidation of COSMOTHERM, ABSOLV, and SPARC. Environmenta Toxicoogy and Chemistry 33(7), Prediction of partition coefficients for compex environmenta contaminants: Vaidation of COSMOtherm, ABSOLV, and SPARC Stenze, A., Goss, K.U. and Endo, S. (2014) Prediction of Partition Coefficients for Compex Environmenta Contaminants: Vaidation of COSMOTHERM, ABSOLV, and SPARC. Environmenta Toxicoogy and Chemistry 33(7),

15 (a) Pot of og Kow versus og Kf for a data. The potted og Kf vaues are the average of a pubished data for compounds isted in Tabe SI-1. Bars indicate the range in data. The bac ine is the inear regression between og Kf and og Kow for a of the data (ogkf = 0.70ogKow ; R2 = 0.65). The dashed circe iustrates the region with the highest range in og Kf vaues (og Kow 5.5). (b) Pot of og Kow versus og Kf for a passing data. The potted og Kf vaues are the average of a passing pubished data for the compounds isted in Tabe SI-1. Bars indicate the range in data. The bac ine is the inear regression between og Kf and og Kow for a of the passing data (ogkf = 0.83ogKow ; R2 = 0.73). The dashed circe iustrates the region with the highest range in og Kf vaues (og Kow 5.5). Difiippo, E.L. and Eganhouse, R.P. (2010) Assessment of PDMS-Water Partition Coefficients: Impications for Passive Environmenta Samping of Hydrophobic Organic Compounds. Environmenta Science & Technoogy 44(18), The End 15