Insight into the desorption behavior of oily soil with different particle sizes based on accumulation effect and binding interaction

A large amount of oily soil (OS) is inevitably generated in the oil exploration and development process, which leads to serious environmental issues . However, the purification of OS remained a great challenge due to the unclear mechanism. In this work, the desorption behavior of OS with different particle sizes was investigated by microemulsion (ME) elution based on the accumulation effect and binding interaction. The oil removal efficiency ( R e $R_e$ ) of OS has been studied in four elution systems. The result confirmed that LAS-M can better remove oil contaminants. In addition, the accumulation effect, the distribution coefficient ( K D $K_D$ ) varied with the solid concentration ( C p $C_p$ ), was elaborated using the SCA-Langmuir model in detail. The results indicated that small particle-size OS has a more significant accumulation effect, which facilitated the desorption of oil molecules. Furthermore, XRD and XRF were employed to detect the soil mineral composition. The FT-IR and zeta potential analysis revealed that the rich feldspar mineral in larger particle-size soil enhanced oil-soil binding interaction, directly leading to a decreased oil desorption capability. Finally, accumulation effect and binding effect revealed that small particle OS (∼41 µm, 89.17%) had higher R e $R_e$ than large particle OS (∼643 µm, 74.23%). The study provided a theoretical basis for the remediation of industrially contaminated soil.