Submitted to: Inform
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/16/1998
Publication Date: N/A
Interpretive Summary: Oilseed processors continue operating under relatively low profit margins and increasing regulatory pressures. Many oilseed processors are presently using commercial hexane as the solvent to extract oil. Commercial hexane is a mixture of 5 to 6 carbon paraffins and can undergo photo oxidation in the air to form ozone. Therefore, it is regulated as a volatile organic compound (VOC). A plant which emits more than 100 tons of VOC per year is required to have a federal operating permit and a fee of more than $30/ton of VOC. N-hexane, which is the main component of commercial hexane, is considered a neutral toxin in pure form. Hence commercial hexane is also regulated as a hazardous air pollutant (HAP) which is regulated at a more stringent limit of 10 tons/year. Plants that emit more than 10 tons n-hexane per year will be asked to apply the maximum achievable control technology (MACT) to minimize the hexane loss. This paper will update the current status of regulatory concerns to the oilseed industry. Simple equations are provided to the oilseed operators to figure out their current levels of VOC and HAP.
Technical Abstract: Hexane has been the main solvent used for vegetable oilseed and other nonpetroleum oil extraction since the 1930's (1). Research to identify an alternative solvent to replace hexane during the last 30 years has been motivated by biorenewability and processing safety of the solvent or its solvency of removing antinutritional factors from oilseeds. Acetone, ethanol and isopropanol are among the most studied alternative solvents (2-4). Each solvent has its unique set of advantages and disadvantages. None of these has yet proven to be acceptable by the oilseed industry. In recent years, the air quality issues related to volatile organic compounds (VOC) and hazardous air pollutants (HAP) and other environmental issues have once again been brought to the attention of researchers and commercial hexane users. There is no totally environmentally friendly solvent available. However, a possible future solution to the oilseed industry is to replace commercial hexane with commercial isohexane (5) or another solvent (6) if the price is acceptable, the availability adequate, and its performance to be equivalent to that of the commercial hexane. This paper addresses the regulatory issues of hydrocarbon solvents and assist the managers of oil mills to assess the amount of VOC and HAP in their plants.