Oil–water separation process with organoclays: A comparative analysis

• Organoclays were prepared via ion exchange reactions using quaternary ammonium salts.
• The capacity of oil sorption by organoclays was evaluated in a finite bath system.
• Factorial experimental design was employed to evaluate the oil removal efficiency.
• The multiple linear regression models exhibited excellent predictions.
• Expansion tests showed that organoclays exhibited a very high adsorption capacity.

This work presents an experimental study focusing on the preparation and characterization of modified green clay with quaternary ammonium salts alkyl dimethyl benzyl ammonium chloride (ADMBAC) and distearyl dimethyl ammonium chloride (DSDMAC) intended to be used as adsorbent in the process of removing oil emulsion in an oil–water system using finite bath. X-ray diffraction (XRD), infrared spectroscopy (IR) and expansion test (adsorption capacity and Foster swelling) measurements were performed in order to evaluate the performance of the ion exchange reactions and the degree of affinity with oil products. There was an increase in the XRD basal spacing of the modified clays (1.96 nm and 2.25 nm for DSDMAC and ADMBAC salts, respectively) in comparison to the observed value (1.56 nm) for the unmodified clay. The IR results revealed that salts were successfully incorporated to clay structure. Based on the expansion tests the organoclays presented the best efficiency of separation, independent on the kind of solvent used in comparison with the unmodified clay performance. The modified clays exhibit a very high capacity of adsorption. The predictions of multiple linear regression models determined based on the factorial design of experiments are excellent.