Vol. 8, No 1, 2011 pp. 31 - 49
UDC 504.3.054:551.575.1 535.247:539.175
MODELING OF THE HAZE-PRODUCING SECONDARY POLLUTANT CONCENTRATIONS IN THE ATMOSPHERE
L.A. Jimoda1, J.A. Sonibare2, F.A. Akeredolu2
1Department of Chemical Engineering, Ladoke Akintola University of Technology, Ogbomoso, Nigeria
2Department of Chemical Engineering, Obafemi Awolowo University, Ile-Ife, Nigeria
Abstract.
In this work we have developed a model for predicting the rate of formation of secondary pollutants in the atmosphere. Haze-producing secondary pollutants including peroxyacetyl nitrate (PAN), Ozone (O3), Nitrate (NO3-) and Sulphate (SO42-) were modeled by determining the rate equation balance for each component. The photochemical chain reaction mechanisms producing the desired secondary pollutants were used to obtain the required rate equation balance so as to set up the resultant first order differential equations. The rate constants for the chosen plug flow reactions were estimated. The initial concentrations of each component in the reactor and rate constants obtained were used in a set of first order differential equations to validate the concentrations of (PAN, NO3-, SO42-, O3). Six-hour samplings in each quarter of a year were carried out for a period of 24 hours to validate the concentrations of secondary pollutants (PAN, HNO3, H2SO4, O3). The ordinary differential equation (ODE) solver of MATLAB 8.0 was used to determine the concentration profiles of the secondary pollutants with a time increment of 1 hour for a period of 24 hours. The result of the reactor modeling showed that peroxyacetyl nitrate (PAN) and NO3- concentrations reduced with sunlight but increased with rainfall while Ozone (O¬3) and Sulphate (SO42-) concentrations increased with sunlight and reduced with rainfall. The developed model results confirmed the variation of the concentration of secondary pollutants with sunlight and rainfall.
Key Words:
haze-producing, secondary pollutants, photochemical reaction, chain reaction
MODEL STVARANJA IZMAGLICE KAO POSLEDICE SEKUNDARNIH KONCENTRACIJA ZAGAĐIVAČA U ATMOSFERI
U ovom radu smo razvili model za predviđanje stope formiranja sekundarnih zagađujućih materija u atmosferi. Zagađivači koji stvaraju izmaglicu, uključujući proizvodnju srednjih perokiacetil nitrata (PAN), ozon (O3), nitrati (NO3-) i sulfat (SO42-) su modelirani određivanjem jednačine bilansa za svaku komponentu. Fotohemijski mehanizmi za proizvodnju sekundarniih zagađivača su korišćeni za dobijanje potrebne ravnoteže bi se dobile neophodne jednačine. Početne koncentracije svake komponente u reaktoru i stopa dobijenih konstanti korišćeni su u skupu prvih jednačina za proveru koncentracije (PAN, NO3-, SO42-, O3). Šestočasovno uzorkovanja u svakom kvartalu godine je sprovedeno u periodu od 24 sata kako bi se potvrdila koncentracija sekundarnih zagađivača (PAN, NO3-, SO42-, O3). Obična diferencijalna jednačina (ODE) Solver programa MATLAB 8.0 je korišćena za određivanje profila koncentraciju sekundarnih zagađivača svakog sata tokom 24 časa.Rezultati su pokazali da su se koncentracije perokiacetil nitrat (PAN) i NO3- smanjile sa sunčevim zracima ali povećale sa padavinama, dok su se koncentracije ozona (O3) i sulfata (SO42-) povećale sa sunčevim zracima a smanjile i sa padavinama. Rezultati dobijeno od razvijenog rezultati potvrdili su varijacije u koncentracijama sekundarnih zagađivača u odnosu na sunce i padavine.
Ključne reči: stvaranje izmaglice, sekundarni zagađivači, fotohemijske reakcije, lančana reakcija
