Sorption of potential ionic pollutants on oil shale and its non-series composite sorbents

Abstract

Huge amounts of anthropogenic environmental pollutants appearing in nature mean an emerging problem. Oil shale is a convenient candidate, wherewith these contaminations can be removed from our natural environment, taking into account its sorption ability and low price. However, oil shale has a crumbling nature, which restricts its facile usage. Hence, oil shale was transformed into more handleable forms, using binding materials. Two oil shale composite forms were prepared by applying sodium alginate and agar. A cationic and an anionic chemicals, benzyltriethylammonium chloride and sodium 2,3-diisopropylnaphthalene-1-sulfonate, respectively, were used as model pollutants, and their sorptions on these newly prepared composites were studied. Sorption properties of oil shale powder and oil shale composites were compared. In the composite materials, oil shale properly sorbed the model pollutants (the binding material did not cover the sorption sites); furthermore, oil shale composites had significantly higher removal efficiency compared to that of the oil shale powder: 208 ± 15.6 (oil shale–agar) and 171 ± 22.8 (oil shale–alginate) vs 140 ± 11.1 µmol/g for the cationic compound; 151 ± 1.6 (oil shale–agar) and 165 ± 7.6 (oil shale–alginate) vs 81.5 ± 2.6 µmol/g for the anionic compound. Results of diffusion models for the two composites show that the opposite charges of the solutes largely influence the rate of their diffusion, owing to the interaction between the solute and the composite material. These results indicate that oil shale and its composites are applicable candidates as sorbents, from which the most effective one can be chosen by considering the chemical properties of the actual pollutant to be removed.