Dissolution Rate of BTEX Contaminants in Water

Abstract

The BTEX group of contaminants consists of benzene, ethylbenzene, toluene, and three isomers of xylene. The dissolution rate, solubility, slick area and mass transfer coefficient were examined for the BTEX. The release of BTEXs into the environment is influenced by their fate and transport mechanisms. Thus, the fate and transport mechanisms are affected by the contaminant characteristics, which vary with the different BTEX compounds. A comprehensive model has been developed to simulate the molecular dissolution rate of BTEX contaminants in a natural water stream. The developed model modifies the work of Cohen et al. (1980) by considering the physicochemical properties of the BTEX compounds and physical processes relevant to the spreading of contaminants in the sea. The model shows that Benzene with greater solubility in water and dissolution coefficient has the largest dissolution rate while o‐xylene with the biggest density has the lowest dissolution rate because of its low fraction. The benzene dissolution rate is about 2.6, 20.6 times that of Toluene, ethylbenzene, respectively, but with a varying proportion with the xylenes. The model has been validated against the theories of mass transfer rate at the surface at appropriate surface area. The developed model can be found useful in prediction and monitoring the dissolution rate of contaminants in soil and water systems.

Planilha de validação: uma nova ferramenta para estimar figuras de mérito na validação de métodos analíticos univariados

“…Estes compostos, em especial o benzeno, atuam como substâncias depressoras do sistema nervoso central e dependendo da concentração e do tempo de exposição podem causar sonolência, tontura, fadiga, narcose e morte, além de apresentarem um potencial cancerígeno quando absorvidos em alta quantidade 27,28 . A contaminação de solo e águas subterrâneas por vazamentos de produtos derivados de petróleo, em especial os hidrocarbonetos voláteis, tem despertado cada vez mais a atenção dos órgãos de controle ambiental, devido ao risco que representam à saúde da população.…”

“…A contaminação de solo e águas subterrâneas por vazamentos de produtos derivados de petróleo, em especial os hidrocarbonetos voláteis, tem despertado cada vez mais a atenção dos órgãos de controle ambiental, devido ao risco que representam à saúde da população. Uma outra grande preocupação é a facilidade com que estes compostos se dispersam no meio ambiente, devido principalmente às suas características físico-químicas como baixo peso molecular e relativa solubilidade em água quando comparados com outros hidrocarbonetos maiores, que permitem a sua rápida difusão por corpos aquáticos e pela zona vadosa do solo [27][28][29] . Os limites de potabilidade de água definidos pelo Ministério da Saúde (Portaria 518 de 25 de Março de 2004) para estes contaminantes são baixos, 5 μg/L para o teor de benzeno, 170 μg/L para tolueno, 200 μg/L para etilbenzeno e 300 μg/L para o teor total de xilenos 30 , e a metodologia analítica para a sua quantificação deve ser robusta também para baixos teores.…”

Treatment of Bio-Oil Refinery Storm Water by a Simulated Constructed Wetland: A Sustainable Management Alternative

“…This can also be a direct result of phytoaccumulation because the contaminants are not degraded in or metabolized by the plant, but rather emitted to the surrounding atmosphere (Knox, Nelson et al 2010). Volatile organic compounds (VOCs) such as chlorinated solvents and benzene, toluene, ethylbenzene and xylene (BTEX) are often treated by constructed wetlands due to their ability to transfer from the water phase to the vapor phase quickly (Njobuenwu, Amadi et al 2005). Hydrophilic compounds such as phenol and acetone are expected to undergo less volatilization than the more hydrophobic compounds such as chlorinated benzenes, chlorinated ethenes and BTEX (Njobuenwu, Amadi et al 2005).…”

“…These contaminates often occur from leakages of underground storage tanks and take place primarily in underground water tables or aquifers phosphorus (Njobuenwu, Amadi et al 2005). These contaminates are considered a great environmental concern due to their toxicity and carcinogenic effect on humans.…”

“…The biodegradation potential of BTEX is very efficient as well as a nondisruptive and cost-effective form of environmental remediation (Wilson and Bouwer 1997). Similar to petroleum hydrocarbons, the rate of biodegradation of BTEX contaminants can be enhanced through the addition of nutrients, such as nitrogen and phosphorus (Njobuenwu, Amadi et al 2005). Also, by the simple addition of oxygen to an anaerobic site contaminated by BTEX can help encourage breakdown (Wilson and Bouwer 1997).…”