Adsorption of Crude Oil and PAHs by Ordinary and Modified Bentonites

Hazardous chemicals are the major cause of soil contamination in the environment. In recent years, to prevent the leaching of pollutants in soils, different stabilization and containment techniques as well as geosynthetic clay liners have been developed in recent years. Organophilic bentonites, due to their large surface areas, negatively charged particles and high adsorption characteristics have many applications for remediation of contaminated sites. The characteristics mentioned above of modified bentonites have enabled them to adsorb contaminants from solutions or to stabilize them in soils. This study focuses on interlayer changes of bentonite clays due to the adsorption of hydrocarbons (i.e. Crude Oil and PAHs). Free swell tests and X-ray diffraction analysis were conducted on the clays. The free swell test results showed that modified bentonites effectively intercalated crude oil into their particles and adsorbed them, hence presenting 410 % volume increase when exposed to this compound. Results of X-ray diffraction analysis for modified bentonite samples indicated a 63.15% and 20.22% interlayer increase after their exposure to the crude oil and PAHs respectively while that of ordinary bentonites was relatively insignificant (0.50% and 2.86%). Similar observations were noted for other hydrocarbonic compounds denoting the organophilic properties of modified bentonites.