Sorption Capacity of Clay Minerals for Oil and Oil Products from Water Areas

Abstract

Oil and oil products are among the most common and most dangerous contaminants of water areas. The spills of oil and oil products are dangerous because of long-term existence and migration, sorption technologies offer an effective remedy. The main purpose of the research was the examination of the possibility of clay minerals use for the sorption of oil and oil products from water surface. Montmorillonite, palygorskite, montmorillonite-palygorskite genetic mixture, illite (Cherkassy deposit, Ukraine), and kaolinites from Ukraine deposits were used in the research. Results show that the sorption of oil and oil products depended on the nature of sorbent and the oil film thickness. With increase in the film thickness the amount of sorbed oil grew. It can be explained by the increase in the contact time of the clay particles and oil. According to our data, the palygorskite and montmorillonite-palygorskite genetic mixture sorbed more quantity of oil and oil products than montmorillonite and illite. For example, at the oil film thickness 550 µm, palygorskite sorbed 217 mg/g, montmorillonite-palygorskite genetic mixture – 188 mg/g, illite – 162 mg/g, montmorillonite – 152 mg/g. High sorption capacity palygorskite and montmorillonite-palygorskite genetic mixture for oil and oil products is due to the texture of palygorskite. Palygorskite crystals are needle-shaped and they form a netted texture with a large quantity of macro-and micropores. The comparison of the sorption of oil and diesel oil by kaolinites from five deposits of Ukraine, showed that the amount of sorbed oil also depends on the particle size and the specific surface area of clay minerals. The kaolinites with larger particles size and, correspondingly, smaller specific surface area sorbed more quantity of oil and oil products. For example, the kaolinite with the particle size 1–5 µm and the specific surface 15–16.7 m2/g at the oil film thickness 550 µm sorbed 720 mg/g, and the kaolinite with the particle size 0.05–0.1 µm and the specific surface 70–80 m2/g sorbed 290 mg/g. The sorption of diesel oil by clay minerals was similar. Palygorskite and montmorillonite-palygorskite genetic mixture sorbed more amount of diesel oil than montmorillonite and illite. However, clay minerals sorbed more quantity of oil than diesel oil. For example, at the film thickness 550 µm, palygorskite sorbed 216 mg/g oil and diesel oil – 197 mg/g. This is probably due to the presence of resins and asphaltenes in oil. They have hydrophobic sites and can be sorbed on hydrophilic sites on clay minerals. The advantage of clay minerals as sorbents of oil and oil products is their environmental friendliness, because they represent natural components of bottom sediment. Furthermore, under anaerobic conditions, microorganisms are capable of decomposing oil into soluble low-toxicity substances. Сlay minerals present may assist this process.