| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 641111 | Separation and Purification Technology | 2014 | 6 Pages |
•Oil recovery from a pre-treated oily sludge via solvent extraction was investigated.•Solid concentration (CS) effect was observed in the solvent extraction tests.•A CS-dependent function of distribution coefficient described the test data.•Effect of solvent and temperature on surface site activity coefficient was examined.
Oil recovery from oily sludge generated from the petroleum industry has been investigated by solvent extraction using four organic solvents, cyclohexane, n-hexanol, n-butanol and kerosene. Special emphasis was placed on the effect of sludge (solid) concentration (CS) on the oil recovery efficiency (RO) and partition coefficient (KD). The KD was found to vary with CS. This phenomenon can be described as the “solid concentration effect” or “solid effect” (CS-effect). The CS-effect can be explained using the surface component activity (SCA) model that we developed previously. In this model, the activity coefficient of solid surface sites (fS) was proposed as a function of CS rather than unity because of interactions among solid particles. Based on the SCA model, we provide a CS-dependent function of partition coefficient (termed the SCA-partition coefficient function), in which the intrinsic (or thermodynamic) partition coefficient KD0 independent of CS can be simulated from extraction experimental data and can be used to characterize the extraction equilibrium. It was confirmed that the SCA-partition coefficient function could describe the CS-effect observed in our solvent extraction experiments accurately. In addition, the fS of the sludge was independent of the solvent in our tests and decreased with increasing temperature.
