Open Access

Modeling perchloroethylene degradation under ultrasonic irradiation and photochemical oxidation in aqueous solution

  • Mahdi Kargar1,
  • Ramin Nabizadeh1Email author,
  • Kazem Naddafi1, 2,
  • Simin Nasseri1, 3,
  • Alireza Mesdaghinia1,
  • Amir Hossein Mahvi1, 4,
  • Mahmood Alimohammadi1,
  • Shahrokh Nazmara1 and
  • Bagher Pahlevanzadeh5
Iranian Journal of Environmental Health Science & Engineering20129:32

https://doi.org/10.1186/1735-2746-9-32

Received: 31 July 2012

Accepted: 22 December 2012

Published: 23 December 2012

Abstract

Sonolysis and photochemical degradation of different compounds such as chlorinated aliphatic hydrocarbons are among the recent advanced oxidation processes. Perchloroethylene is one of these compounds that has been mainly used as a solvent and degreaser. In this work, elimination of perchloroethylene in aqueous solution by ultrasonic irradiation, andphotochemical oxidation by ultra violet ray and hydrogen peroxide were investigated. Three different initial concentrations of perchloroethylene at different pH values, detention periods, and concentrations of hydrogen peroxide were investigated. Head space gas chromatography with FID detector was used for analyses of perchloroethylene. This research was performed in 9 months from April through December 2011.

Results showed that perchloroethylene could be effectively and rapidly degraded by ultrasonic irradiation, photochemical oxidation by ultra violet ray, hydrogen peroxide and a combination of these methods. Kinetics of perchloroethylene was strongly influenced by time, initial concentration and pH value. Degradation of Perchloroethylene increased with decrease in the initial concentration of perchloroethylene from 0.3 to 10 mg/L at all initial pH. The results showed an optimum degradation condition achieved at pH = 5 but did not affect significantly the perchloroethylene destruction in the various pH values. Kinetic modeling applied for the obtained results showed that the degradation of perchloroethylene by ultrasound and photo-oxidation followed first order and second order model. The percentage of removal in the hybrids reactor was higher than each of the reactors alone, the reason being the role of hydroxyl radical induced by ultrasound and photochemical reaction.

Keywords

Perchloroethylene Ultrasound Photochemical oxidation Kinetics models

Introduction

AS the number of substances resistant to biodegradation have increased, and the conventional biological methods were unable to complete the treatment of these materials; Therefore, new technologies are required to degrade these resistant molecules to smaller ones. The smaller molecules can be degraded by biological processes [1]. New technologies include advanced oxidation processes such as Fenton, peroxone, common use of ozone, UV irradiation, hydrogen peroxide and the use of ultrasonic and photo-catalytic oxidation processes [2]. One category of resistant material to biological degradation is chlorinated hydrocarbons. These materials cause water resources contamination and affect human health. Several studies have been carried out in removing various organic materials from water and aqueous solutions [36].

Perchloroethylene (PCE) is a chlorinated hydrocarbon that has been mainly used as a solvent in dry cleaning, degreaser in metal parts manufacturing, and as a precursor in the production of chlorofluorocarbons [7, 8]. Perchloroethylene is included in products such as motor vehicle cleaners, stain removers, adhesive and wood cleaners [9, 10]. It is a volatile, nonflammable and colorless liquid with a stench that has odor threshold of 1 ppm [9]. The summary of PCE physical properties are shown in Table 1[11].
Table 1

PCE properties (EPA, 1994)

Molecular Weight(g/mol)

Chemical formula

Density at 20°C(g/mL)

Solubility*at 25°C(mg/L)

Melting point(°C)

Boiling point(°C)

Henrys law constant (atm.m3/mol)

165.85

C2Cl4

1.63

150

−22

121

1.8 × 10-2

*Solubility in water.

Various applications and inappropriate handling and disposal, results in detection of PCE in groundwater, surface water, wastewater, air and food [1216]. PCE is considered as a probable carcinogenic chemical (Group 2A) to humans [9]. It has also many other adverse health effects [712, 17], due to which United State Environmental Protection Agency (US.EPA) has set the maximum contaminant level (MCL) and maximum contaminant level goal (MCLG) for PCE as 0.005 mg/L and zero, respectively [18].

Conventional water and wastewater treatment processes have poor efficiency in removal of chlorinated compounds such as PCE [19]. Advanced processes such as membrane process, granular activated carbon and air stripping are effective for removal of chlorinated compounds but they are expensive and transfer the contamination to another phase [20]. A large number of new technologies have been emerged that include sonochemistry, photochemistry, electrochemistry and combined treatment methods such as reductive dehalogenation and biodegradation for the degradation of chlorinated compounds [19]. Advanced oxidation processes (AOPs) are able to degrade chlorinated compounds such as PCE into less harmful compounds by using a combination of ultraviolet radiation, H2O2 and ultrasonic waves. Ultrasonic waves are hydroxyl radicals produced during cavitations. Therefore ultrasonic waves are among the advanced oxidation processes [20].

Several studies have been performed on application of photochemical oxidation and sonolysis especially at low concentrations in removal of various pollutants [2022]; but there are few studies regarding PCE degradation by sonolysis and photochemical oxidation (UVC/ H2O2) at micromolar concentration and with a 130 kHz frequency ultrasound. In this work, the degradation rates of PCE at different concentration levels and different pH levels with using an ultrasound bath at 130 kHz frequency and photochemical oxidation with UVC/ H2O2 were studied. Continuous models of PCE degradation were also determined.

Materials and methods

Experimental setup

This experimental research was conducted at the Department of Environmental Health Engineering at Tehran University of Medical Sciences between April and December 2011. Ultrasound bath of the solution in a 300 mL glass reactor (Figure 1) was performed with a 130 kHz frequency and acoustic intensity of 2.5 W/cm2 (Table 2). The characteristics of UVC reactor (Figure 2) are shown in the Table 3.
Figure 1

Ultrasonic equipment.

Figure 2

A schematic of UVC equipment.

Table 2

Characteristics of ultrasound reactor used in the experiments

Parameters

Characteristics

Frequency

35-130kHz

Power

500W

Acoustic Intensity

2.5W/cm 2

Flow type

Batch

Reactor volume

3.7 Liter

Dimensions

L = 30cm, W = 25cm, H = 32cm

Table 3

Characteristics of UVC reactor used in the experiments

Parameters

Characteristics

Model

TUV

Company

Philips

Power(Watt)

55(low pressure mercury)

Intensity(W/cm2)

52

Wavelength(nm)

253.7

Flow type

Batch

Reactor volume

8 Liter

Reactor dimensions

d = 15cm, L = 100cm

UV lamp dimensions

d = 20mm L = 90cm

Solutions of different concentrations of PCE (0.30, 3 and 10 mg/L) were prepared by dissolving PCE (Merck Co., Germany) in distilled water. The concentrations of H2O2 were 10, 50 and 100 mg/L. Temperature was monitored during sonication and maintained constant at 25°C by cooling water. Samples were taken from the ultrasonic and UV reactors at given reaction times (5, 10, 20, 30, 40, 50 and 60 min). The number of samples (regarding pH, time, and concentration as variables) was 63 for each reactor.

Analytical methods

Analyses were performed by head-space gas chromatography technique. Concentrations of PCE samples were determined through GC-FID analysis (VARIAN CP-3800, Australia). The gas chromatograph was fitted with a CP-Sil 8 CB capillary column (30 m, 0.32 mm ID, 0.25 μm film thickness). The injector temperature was 150°C, initial oven temperature was 35°C (held for 1 min) and increased to 100°C at a rate of 16°C/min, held for 5 min. The inlet (200 μL) was operated in 20% split mode. Helium (99.999%) was used as the carrier gas at 1 mL min-1. The lowest detection level (MDL) for PCE analysis by GC with the above mentioned method was 5 μg/L.

Results and discussion

Aqueous solution with initial concentrations of (0.3, 3, and 10 mg/L) for PCE at different pH values were sonicated and photochemically oxidated. The investigation was carried out in six reactors (Table 4). The efficiency at different pH values and kinetic constants in these reactors are illustrated in Tables 5, 6 and 7. The mean removal efficiency in the US/UVC/ H2O2 reactor at various concentrations of H2O2 is illustrated in Table 8 and Figures 3, 4, 5, respectively.
Figure 3

Degradation of aqueous solution of 10 mg/L at different pH subjected to ultrasound and UVC/H 2 O 2 (100 mg/L); T = 25°C.

Figure 4

Degradation of aqueous solution of 0.3 mg/L at different pH subjected to ultrasound and UVC/H 2 O 2 (100 mg/L); T = 25°C.

Figure 5

Degradation of aqueous solution of 3 mg/L at different pH subjected to ultrasound and UVC/H 2 O 2 (100 mg/L); T = 25°C.

Table 4

Models of perchloroethylene degradation under various reactors

Reactor

Model of reactor

US

y= 1. 725 + 0.304 C in 0.461 p H 0.012 T i m e + 0.018 int C in . p H 0.005 int C in . T i m e + 0.0001 s q T i m e + 0.008 s q C in

UVC

y = − 3. 5 + 1.31pH + 0.029 int C in . pH − 0.004 int C in . Time − 0.084sqpH + 0.035sqC in

US + UVC

y= 0. 286 + 0.138 C in 0.0161 p H + 0.007 int C in . p H 0.002 int C in . T i m e + 0.0001 s q T i m e 0.005 s q C in

UVC + US + H2O2 10mg/L

y= 0. 296 + 0.454 C in 0.024 T i m e + 0.01 int C in . p H 0.004 int C in . T i m e + 0.0001 s q T i m e 0.023 s q C in

UVC + US + H2O2 50mg/L

y = 0.324 + 0.269C in  − 0.024Time − 0.003 int C in . Time + 0.0001sqTime − 0.006sqC in

UVC + US + H2O2 100mg/L

y= 1. 253 + 0.181 C in 0.343 p H 0.025 T i m e 0.002 i int C in . T i m e + 0.029 s q p H + 0.0001 s q T i m e 0.009 s q C in

Table 5

Mean efficiency and kinetic order degradation of PCE at various pH, subjected to US reactor

C0(mg/L)

pH

Efficiency (%)

K (1/min)

Reaction order

10

9

57.31

0.0094

First

10

7

64.54

0.0148

First

10

5

65.31

0.0162

First

3

9

58.27

0.0155

Second

3

7

68.56

0.0157

Second

3

5

70.31

0.0184

Second

0.3

9

29.38

0.043

Second

0.3

7

35.57

0.037

Second

0.3

5

39.42

0.0606

Second

Table 6

Mean efficiency and kinetic order degradation of PCE at various pH, subjected to UVC reactor

C0( mg/L)

pH

Efficiency (%)

k(1/min)

Reaction order

10

9

53.81

0.0082

First

10

7

49.65

0.0056

First

10

5

62.58

0.0137

First

3

9

76.15

0.0148

First

3

7

77.16

0.0181

First

3

5

82.61

0.023

First

0.3

9

69.42

0.0287

First

0.3

7

66.42

0.0247

First

0.3

5

74.76

0.0391

First

Table 7

Mean efficiency and kinetic order degradation of PCE at various pH, subjected to US/UVC reactor

C0( mg/L)

pH

Efficiency (%)

k(1/min)

Reaction order

10

9

88.85

0.0194

First

10

7

91.36

0.0221

First

10

5

91.89

0.0215

First

3

9

82.97

0.035

First

3

7

88.057

0.0518

First

3

5

86.67

0.0545

First

0.3

9

71.24

0.0436

First

0.3

7

81.38

0.0339

First

0.3

5

82.05

0.0393

First

Table 8

Mean efficiency degradation of PCE at various pH, subjected to US/UVC/ H 2 O 2 reactor

C0( mg/L )

pH

Efficiency of UVC + US + H2O2reactor (%)

With 10mg/L H2O2

With 50mg/L H2O2

With 100mg/L H2O2

10

9

81.97

88.97

94.05

10

7

83.79

89.59

96.84

10

5

85.79

93.77

97.06

3

9

65.0

79.2

79.076

3

7

67.83

87.83

94.16

3

5

71.98

88.9

94.6

0.3

9

62.58

78.33

82.28

0.3

7

72.52

83.09

85.5

0.3

5

78.52

85.38

87.95

Regression analysis was used for modeling of perchloroethylene degradation under various reactors. To calculate the effluent concentration and efficiency, the effluent concentration (y), pH (5–9), time (5 to 60 min) and initial concentration ( 0.3 to 10 mg/L) were considered as independent variables in the model (Table 4) for each reactor.

Parameters that had a significant difference were included in the model (Table 4). These parameters include main variables (pH, primary concentration of PCE and time), interaction and square of main variables. For example, in the US reactor pH, initial concentration (Cin), time, interaction Cin, pH and interaction Cin, time and square Cin and time have a significant difference. These models can be used to calculate the efficiency of those concentrations for which the test was not performed (such as 1 mg/L).

Decomposition of PCE in the ultrasonic reactor with 10 mg/L of concentration, UVC, UVC/US and UVC + US + H2O2 reactor in all concentrations followed first order kinetics model and in the ultrasonic reactor for 3 and 0.3 mg/L of concentration followed second order kinetics model. Also with increasing the initial concentration of PCE, the apparent first and second order rate constants decreased, indicating non–elementary nature of the photochemical and sonolysis reactions. Most investigators have observed the kinetics of photolysis and sonolysis of pollutants to be first order [2326].

This dependence of degradation rate constants on initial concentration was similar to other studies [20, 23, 27]. Degradation rate of PCE at pH = 5 was higher than the other pH levels, but the difference between the other pH values were not significant.

The consumed energy by various reactors for treatment of 1 m3 of contaminated water is illustrated in the Table 9. As shown in Table 9 the energy consumption in the hybrid process (UVC + US + H2O2 100 mg/L) is the lowest, while the Ultrasonic process has a maximum consumed energy.
Table 9

Consumed energy by various reactors[28]

Reactor

Concentration(mg/L)

Concentration(mg/L)

Concentration(mg/L)

 

0.3

0.3

0.3

 

Consumed energy (kw/m3)

US

1389

714

595

UVC

153

61

63

US + UVC

420

317

77

UVC + US + H2O2 10mg/L

652

451

353

UVC + US + H2O2 50mg/L

292

75

30

UVC + US + H2O2 100mg/L

25

15

5

The hybrid methods showed higher efficiencies compared to the single reactors. The reactors’ efficiency from high to low are illustrated below:
UVC + US + H 2 O 2 10 mg / L > UVC + US + H 2 O 2 50 mg / L > UVC + US >
UVC + US + H 2 O 2 10 mg / L > UVC > US

Conclusion

Sonolysis and photochemical degradation of PCE were performed under various experimental conditions such as initial concentration, pH, time of reaction and type of reactor. The reduction of initial concentration of PCE increased the degradation rate of PCE increased and parallel to the increase of initial concentration, the degradation rate constant declined, but the initial pH of the solution did not significantly affect the PCE destruction. It was shown that the application of UVC + US + (H2O2 100 mg/L) could effectively remove PCE in 60 minute. Therefore, the mentioned hybrid process can be considered as process for complete removal of PCE in reasonable detention time. Furthermore, Lower energy consumption of the hybrid process compared to the other methods, make it more feasible to be used in full scale PCE removal practice.

Declarations

Acknowledgements

This research has been supported by Tehran University of Medical Sciences, grant No. 90-01-27-13428.

Authors’ Affiliations

(1)
Department of Environmental Health Engineering, School of public Health, Tehran University of Medical Sciences
(2)
Center for Air Pollution Research, Institute for Environmental Research, Tehran University of Medical Sciences
(3)
Center for Water Quality Research, Institute for Environmental Research, Tehran University of Medical Sciences
(4)
Center for Solid Waste Research, Institute for Environmental Research, Tehran University of Medical Sciences
(5)
Department of Epidemiology and Biostatistics, School of public Health, Tehran University of Medical Sciences

References

  1. Lifka J, Ondruschka B, Hofmann J: The use of ultrasound for the degradation of pollutants in water: Aquasonolysis -a review. Eng Life Sci. 2003, 3: 253-262. 10.1002/elsc.200390040.View ArticleGoogle Scholar
  2. Naffrechoux E, Chanoux S, Petrier C, Suptil J: Sonochemical and photochemical oxidation of organic matter. Ultrason Sonochem. 2000, 7: 255-259. 10.1016/S1350-4177(00)00054-7.View ArticleGoogle Scholar
  3. Nasseri S, Vaezi F, Mahvi AH, Nabizadeh R, Haddadi S: Determination of the ultrasonic effectiveness in advanced wastewater treatment. Iran J Environ Healt. 2006, 3: 109-116.Google Scholar
  4. Mahvi AH, Maleki A, Alimohamadi M, Ghasri A: Photo-oxidation of phenol in aqueous solution: toxicity of intermediates. Korean J Chem Eng. 2007, 24: 79-82. 10.1007/s11814-007-5013-4.View ArticleGoogle Scholar
  5. Rezaee A, Ghaneian MT, Khavanin A, Hashemian SJ, Moussavi GH, Ghanizadeh GH, Hajizadeh E: Photochemical oxidation of reactive blue 19 dye in textile wastewater by UV/K2S2O8 process. Iran J Environ Healt. 2008, 5 (2): 95-100.Google Scholar
  6. Movahedyan H, Seid Mohammadi AM, Assadi A: Comparison of different advanced oxidation processes degrading p- chlorophenol in aqueous solution. Iran J Environ Healt. 2009, 6 (3): 153-160.Google Scholar
  7. Poli D, Manini P, Andreoli R, Franchini I, Mutti A: Determination of dichloromethane, trichloroethylene and perchloroethylene in urine samples by headspace solid phase microextraction gas chromatography–mass spectrometry. J Chromatogr B. 2005, 820: 95-102. 10.1016/j.jchromb.2005.03.009.View ArticleGoogle Scholar
  8. Rastkari N, Yonesian M, Ahmadkhaniha R: Exposure assessment to trichloroethylene and perchloroethylene for workers in the dry cleaning industry. Bull Environ Contam Toxicol. 2011, 86: 363-367. 10.1007/s00128-011-0244-9.View ArticleGoogle Scholar
  9. ATSDR: Toxicological Profile for Tetrachloroethylene (Update), U.S. Public Health Service, U.S. 1997, Atlanta, GA: Department of Health and Human ServicesGoogle Scholar
  10. Costa C, Barbaro M, Catania S, Silvari V, Geomano MP: Cytotoxicity evaluation after co exposure to perchloroethylene and selected per oxidant drugs in rat hepatocytes. Toxicology in Vitro. 2004, 18: 37-44. 10.1016/S0887-2333(03)00133-4.View ArticleGoogle Scholar
  11. EPA: Chemical Summary For Perchloroethylene Prepared By Office Of Pollution Prevention and Toxics U.S. Environmental Protection Agency. 1994, EPA 749-F-94-020aGoogle Scholar
  12. Kargar M, Nadafi K, Nabizadeh R, Nasseri S, Mesdaghinia A, Mahvi AH: Survey of hazardous organic compounds in the groundwater, air and wastewater effluents near the Tehran automobile industry. Bull Environ Contam Toxicol. 2012, in pressGoogle Scholar
  13. Kostopoulou MN, Spyros K, Golfinopoulos SK, Nikolaou AD, Xilourgidis NK, Lekkas TD: Volatile organic compounds in the surface waters of Northern Greece. Chemosphere. 2000, 40: 527-532. 10.1016/S0045-6535(99)00293-3.View ArticleGoogle Scholar
  14. Ras-Mallorqui MR, Marce-Recasens RM, Ballarin FB: Determination of volatile organic compounds in urban an industrial air from Tarragona by thermal desorption and gas chromatography–mass spectrometry. Talanta. 2007, 72: 41-950.View ArticleGoogle Scholar
  15. Srivastava A, Majumdar D: Emission inventory of evaporative emissions of VOCs in four metro cities in India. Environ Monit Assess. 2010, 160: 315-322. 10.1007/s10661-008-0697-4.View ArticleGoogle Scholar
  16. Albergaria JT, Alvim- Ferraz MCM, Delerue-Matos MCF: Estimation of pollutant partition in sandy soils with different water contents. Environmental monitoring and assessment. 2010, 171 (1–4): 171-180.View ArticleGoogle Scholar
  17. Lawrence HL, Jean CP: Hepatic and renal toxicities associated with perchloroethylene. Pharmacol Rev. 2001, 53: 177-208.Google Scholar
  18. EPA, US Environmental Protection Agency: National primary and secondary drinking water standard. Office of Water (4606M), EPA 816-F-03-016. 2003, Available from http://www.epa.gov/safewater,Google Scholar
  19. Saez V, Esclapez MD, Tudela I, Bonete P, Louisnard O, Gonzalez-Garcia J: 20 kHz sonoelectrochemical degradation of perchloroethylene in sodium sulfate aqueous media: Influence of the operational variables in batch mode. J Hazard Mater. 2010, 183: 648-654. 10.1016/j.jhazmat.2010.07.074.View ArticleGoogle Scholar
  20. Dobaradaran S, Mahvi AH, Nabizadeh R, Mesdaghinia A, Naddafi K, Yunesian M, Rastkari N, Nazmara S: Survey on degradation rates of trichloroethylene in aqueous solutions by ultrasound. Iran J Environ Healt. 2010, 7 (3): 307-312.Google Scholar
  21. Maleki A, Mahvi AH, Mesdaghinia AR, Naddafi K: Degradation and toxicity reduction of phenol by ultrasound waves. B Chemical Soc Ethiopia. 2007, 21: 33-38.Google Scholar
  22. Maleki A, Mahvi AH, Ebrahimi R, Zandsalimi Y: Study of photochemical and sonochemical processes efficiency for degradation of dyes in aqueous solution. Korean J Chem Eng. 2010, 27 (6): 1805-1810. 10.1007/s11814-010-0261-0.View ArticleGoogle Scholar
  23. De Visscher A, Van Eenoo P, Drijvers D, Van Langenhove H: Kinetic model for the sonochemical degradation of monocyclic aromatic compounds in aqueous solution. J Phys Chem. 1996, 100 (28): 11636-11642. 10.1021/jp953688o.View ArticleGoogle Scholar
  24. Feiyan C, Pehkonen SO, Ray MB: Kinetics and mechanisms of UV-photodegradation of chlorinated organics in the gas phase. Water Res. 2002, 36 (17): 4203-4214. 10.1016/S0043-1354(02)00140-9.View ArticleGoogle Scholar
  25. Jiang Y, Petrier C, David Waite T: Kinetics and mechanisms of ultrasonic degradation of volatile chlorinated aromatics in aqueous solutions. Ultrason Sonochem. 2002, 9 (6): 317-323. 10.1016/S1350-4177(02)00085-8.View ArticleGoogle Scholar
  26. Shirayama H, Tohezo Y, Taguchi S: Photodegradation of chlorinated hydrocarbons in the presence and absence of dissolved oxygen in water. Water Res. 2001, 35 (8): 1941-1950. 10.1016/S0043-1354(00)00480-2.View ArticleGoogle Scholar
  27. Hoffmann MR, Hua I, Hochemer R: Application of ultrasonic irradiation for the degradation of chemical contaminants in water. Ultrason Sonochem. 1996, 3 (3): S163-S172. 10.1016/S1350-4177(96)00022-3.View ArticleGoogle Scholar
  28. Goel M, Hongqiang H, Mujumdar AS, Ray MB: Sonochemical decomposition of volatile and non-volatile organic compounds-a comparative study. Water Res. 2004, 38 (19): 4247-61. 10.1016/j.watres.2004.08.008.View ArticleGoogle Scholar

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