Novel aqueous foams for suppressing VOC emission

Reducing volatile organic compound (VOC) emissions from crude oil/gasoline distribution and storage facilities is important in controlling environmental pollution and enhancing workplace safety. Stable aqueous foam formulations are developed to provide a mass transfer barrier to the emission of VOCs during loading of gasoline. Experiments are carried out in a bench-scale foam cell using liquid hexane as oil. The foam columns of 32 cm in height were able to suppress the plateau concentration of hexane vapors in the effluent by 87% under experimental conditions tested. Vapor suppression increased with foam height but was almost insensitive to liquid viscosity. These experiments are then upscaled from bench-scale to a vessel having an exposed surface area of roughly 2 orders of magnitude higher. Gasoline is used as oil in the upscaled experiments, and the concentrations of volatile hydrocarbons in the effluent are measured during oil loading. A 40-cm-thick foam column is found to reduce the emissions by 96% for foams prepared with deionized water and by 93.8% for foams prepared with 3.5 wt % NaCl brine for 10 h of oil loading.