Insight into Washing of Wet and Dry Crude Oil‐Contaminated Soil

Abstract

Two types of artificial oil‐contaminated soils (OCS) are prepared upon mixing sandy soil with water and crude oil in different proportion. OCS‐I represents the contaminated dry soil and OCS‐II the contaminated wet soil. Soil and crude oil are characterized through infrared spectroscopy and zeta potential analysis, and the OCS microstructure model has been discussed. It is speculated that the polarity petroleum components (e.g., non‐hydrocarbons) are higher in the oil layer of the neighboring soils, forming a “polarity bottom layer.” In OCS‐I, the “polarity bottom layer” is tightly adhered to soil and exhibits poor mobility. This layer is difficult to separate from soil through washing, thereby resulting in a low oil removal rate (ORR). In OCS‐II, the petroleum and soil are separated by a water film with high liquidity. During washing, the “polarity bottom layer” is easily separable from soil, thereby resulting in a high removal rate of polarity component in crude oil and high ORR as well. Based on the results of this study, it could be concluded that OCS‐I is much more difficult to be washed than OCS‐II when these two types of soils contain relatively same amount of substance content (oil, water, and other crude oil groups).

Archives of Environmental Protection

“…These observations are in agreement with the report of Qi, B. et al (2021) on the effect of dry and wet soil on oil removal, where they found that the dry soil (even for sandy soil, which is relatively easy to wash) is selective and the adherence of the strong polarity compounds presented in the crude oil exhibits difficult mobility (Qi et al 2021).…”