Description
In the United States, more than 50% of the population relies on groundwater as their primary source of drinking water. Petroleum products are a major source of groundwater contamination. Gasoline, a major petroleum product, consists of a mixture of hydrocarbons that are toxic to humans and can be found in many groundwater supplies. BTEX (benzene, toluene, ethylbenzene and xylene) are monocyclic aromatic hydrocarbons that are found in gasoline and are highly toxic. Ethanol is an organic solvent and is completely miscible in water. When the gasoline-ethanol mixture comes into contact with water, the ethanol will partition to the water phase. The partitioning into the water phase decreases the polarity of the water and can increase the solubility of BTEX compounds. The main objective of this research is to investigate the influence of ethanol on the adsorption capacity and desorption rate of BTEX compounds on soil. To accomplish the objective of the research, a number of experiments were planned, designed, and conducted. Analysis of the adsorption results indicates that higher ethanol concentrations result in lower adsorption capacity of BTEX compounds on soil. This is true for both bentonite and kaolin experimental results. As ethanol content increasers from a 0% to 50% ethanol, the adsorption capacity for benzene, toluene and ethylbenzene on bentonite decreased by 85%, 99.8%, and 91.3%, respectively. For benzene, toluene and ethylbenzene adsorption on kaolin, with a 0% to 50% ethanol content increase, the adsorption capacity decreased by 88.5%, 92.8%, and 93.2%, respectively. The results of desorption experiments indicate that as the ethanol content increases, the desorption rate of BTEX compounds from soil increases. The desorption rate of benzene and ethylbenzene on bentonite with an ethanol content increase from 0% to 25% resulted in an increase in desorption rate of 770% and 240%, respectively. For toluene, with an ethanol content increase from 0% to 50%, a desorption rate increase of 750% was observed. In conclusion, ethanol decreases the ability of soil to adsorb BTEX contaminants, causing the impact of BTEX contamination in drinking water supplies to be greater. Similarly, ethanol increases the desorption rate of already sorbed BTEX compounds on soil, causing contaminated sites to release BTEX compounds into the groundwater supply.
