Modeling of Absorption of NO2 with Chemical Reaction in a Falling Raindrop

Vishnu Pareek; Vinod K. Srivastava; Adesoji A. Adesina

Korean Journal of Chemical Engineering, Vol.20, No.2, 328-333, March, 2003

DOI10.1007/BF02697248 Export Citation

Modeling of Absorption of NO2 with Chemical Reaction in a Falling Raindrop

Vishnu Pareek^†, Vinod K. Srivastava¹, and Adesoji A. Adesina²

Department of Chemical Engineering, Curtin University of Technology, GPO Box U1987, Perth, WA, 6845, Australia
¹Department of Chemical Engineering, Indian Institute of Technology Hauz Khas, New Delhi, India
²School of Chemical Engineering and Industrial Chemistry, University of New South Wales, Sydney 2052, Australia

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A model has been proposed for the scavenging of NO2 in a falling raindrop. After absorption, aqueous NO2 undergoes a second order reaction to form various ions such as NO2(-), NO3(-) and H(+). The model is based on the unsteady state convective diffusion equation, which was solved for given boundary conditions by using implicit alternate direction (ADI) method. The circulation of fluid inside and outside the raindrop has been taken into account to realistically describe the flow field in the numerical domain. The model predictions indicate that the pH of a raindrop is a direct function of the drop size and bulk concentration of NO2. The model predicted a pH of about 4.9 for a 100-micron raindrop falling through a 20-ppb ambient concentration of NO2. For the same ambient concentration of NO2, a 10-micron raindrop would have a pH of about 4.75. The predictions also suggested that for all practical purposes the gas phase resistance may be taken as the rate-controlling step. The predicted values of gas-side mass transfer coefficient compared well with the estimated values using standard mass transfer correlations.

Keywords:Absorption;Acid Rain;Scavenging;Raindrop;Finite Difference

[References]

Ahmed AFM, Singh RP, Elmubarak AH, Atmospheric Environ., 24A, 2927 (1990)
Baboolal LB, Pruppacher HR, Topalian JH, J. Atmospheric Sci., 38, 856 (1981)
Bambauer A, Brantner B, Paige M, Novakov T, Atmospheric Environ., 28, 3225 (1994)
Beard KV, J. Atmospheric Sci., 33, 851 (1976)
Bird RB, Stewart WE, Lightfoot EN, "Transport Phenomena," John Wiley & Sons, New York (1960)
Carnahan B, Luther HA, Wilkes JO, "Applied Numerical Methods," John Wiley and Sons, New York (1969)
Hales JM, Atmospheric Environ., 6, 635 (1972)
LeClair BP, Hamielec AE, Pruppacher HR, Hall WD, J. Atmospheric Sci., 29, 728 (1972)
Metcalfe SE, Whyatt JD, Broughton R, Derwent RG, Finnegan D, Hall J, Mineter M, O'Donoghue M, Shutton MA, Environ. Sci. Policy, 4, 25 (2001)
Saxena A, Kulshrestha UC, Kumar N, Kumari KM, Srivastava SS, Atmospheric Environ., 30, 3405 (1996)
Schwartz SE, White WH, Adv. Environ. Sci. Technol., 12, 1 (1983)
Schwartz SE, White WH, Environ. Sci. Technol., 4, 1 (1981)
Seinfeld JH, "Atmospheric Chemistry and Physics of Air Pollution," John Wiley & Sons, New York, 195 (1986)
Srivastava VK, "The Thermal Cracking of Benzene in a Pipe Reactor," Ph.D. Thesis, University of Wales, Swansea (UK) (1981)

[Referenced By]

[1] Ahmed AFM, Singh RP, Elmubarak AH, Atmospheric Environ., 24A, 2927 (1990)

[2] Baboolal LB, Pruppacher HR, Topalian JH, J. Atmospheric Sci., 38, 856 (1981)

[3] Bambauer A, Brantner B, Paige M, Novakov T, Atmospheric Environ., 28, 3225 (1994)

[4] Beard KV, J. Atmospheric Sci., 33, 851 (1976)

[5] Bird RB, Stewart WE, Lightfoot EN, "Transport Phenomena," John Wiley & Sons, New York (1960)

[6] Carnahan B, Luther HA, Wilkes JO, "Applied Numerical Methods," John Wiley and Sons, New York (1969)

[7] Hales JM, Atmospheric Environ., 6, 635 (1972)

[8] LeClair BP, Hamielec AE, Pruppacher HR, Hall WD, J. Atmospheric Sci., 29, 728 (1972)

[9] Metcalfe SE, Whyatt JD, Broughton R, Derwent RG, Finnegan D, Hall J, Mineter M, O'Donoghue M, Shutton MA, Environ. Sci. Policy, 4, 25 (2001)

[10] Saxena A, Kulshrestha UC, Kumar N, Kumari KM, Srivastava SS, Atmospheric Environ., 30, 3405 (1996)

[11] Schwartz SE, White WH, Adv. Environ. Sci. Technol., 12, 1 (1983)

[12] Schwartz SE, White WH, Environ. Sci. Technol., 4, 1 (1981)

[13] Seinfeld JH, "Atmospheric Chemistry and Physics of Air Pollution," John Wiley & Sons, New York, 195 (1986)

[14] Srivastava VK, "The Thermal Cracking of Benzene in a Pipe Reactor," Ph.D. Thesis, University of Wales, Swansea (UK) (1981)