Remediation of oil spills using zeolites

Abstract

Current research is testing the hypothesis that zeolites can efficiently and cost effectively adsorb oil spills. To date, this aspect of zeolites science has received little attention. A series of five Master of Science (M.Sc.) Projects at the University of Wolverhampton have shown that the zeolite clinoptilolite can effectively adsorb oil. Various sand-clinoptilolite mixes were tested in replicated laboratory analyses in terms of their ability to adsorb engine oil. Adsorption increased with clinoptilolite amount. The relationship between percentage clinoptilolite and oil adsorption was asymptotic. Thus, on a cost-effective basis, a 20% clinoptilolite: 80% sand mix seems the most costeffective mix. However, a particularly exciting finding was that it was possible to burn the oil-sand-zeolite mix and reuse the ignited mix for further oil adsorption. Experiments are ongoing, but to date the ignition and adsorption cycle has been repeated, on a replicated basis, seven times. Still, the ignited mix adsorbs significantly more oil than the sand control. Initial results suggest that the temperature of ignition is critical, as high temperatures can destroy the crystal and micro-pore structure of zeolites. Thus, low temperature ignition (~400oC) seems to allow the retention of structural integrity. Similar results were obtained using the zeolite chabazite and experiments are in progress on phillipsite, which is the third major zeolite mineral. If the hypotheses can be proven, there are potentially immense benefits. Sand-zeolite mixtures could be used to effectively adsorb terrestrial oil spills (i.e. at oil refinery plants, road accidents, beach spills from oil tankers and spills at petrol stations) and thus remediate oil-contaminated soils. The contaminated mix could be ignited and, given the appropriate infrastructure, the energy emission of combustion could be used as a source for electrical power. Then, the ignited mix could be reused in subsequent oil spills. This offers enormous potential for an environmentally-friendly sustainable ‘green’ technology. It would also represent intelligent use of zeolite resources. On a global scale, including Europe, clinoptilolite is the most common and inexpensive zeolite resource.