Ionic flocculation and liquid-liquid extraction using surfactant and microemulsified systems for removal of oil from produced water
oil produced water; surfactants; microemulsions; ionic flocculation; liquid-liquid extraction.
The produced water (PW) is one of the main sources of pollution derived from the oil industry and represents one of the most important environmental concerns. In this work, surfactants and microemulsion systems were used to remove dispersed oil from the PW by ionic flocculation and liquid-liquid extraction methods. For experiments involving ionic flocculation, an unprecedented alternative was presented for the removal of oil from water produced using ionic surfactant saponified coconut oil (SSCO) as part of the capture of oil by micellar solubilization, followed by ionic flocculation by Ca+2 ions. A factorial experimental design was applied in order to optimize the oil removal process (ER). The experiments investigated the influence of surfactant concentration + CaCl2 (C), temperature (T) and agitation speed (v), obtaining ER = 70.02-91.49%. Subsequently, the pH influence, CaCl2/surfactant ratio and oil removal kinetics (t) were evaluated in the system with the highest ER, obtaining ER = 100%. Then, the optimal system for greater oil removal was reproduced using microemulsions as flocculants having SSCO as a surfactant, presenting ER = 100%. Thus, it can be said that the application of ionic flocculation using SSCO is an efficient technique in the treatment of PW. For experiments involving liquid-liquid extraction, the systems used were composed of PW as an aqueous phase; aviation kerosene as an oil phase; isoamyl alcohol and 1-butanol as cosurfactant agents; and Dissolvan® and Lipesa® as surfactants. An experimental planning was applied to optimize the process and the experiments were carried out according to the Scheffé network, showing oil removal efficiencies (ER) between 24-99%. The microemulsion extraction point used for the optimization of the process was composed of 60% by weight of AP, 5% by weight of kerosene and 35% by weight of the cosurfactant/surfactant ratio (C/S = 9 ratio). The effects of the C/S ratio, microemulsion load capacity, oil removal kinetics, temperature, and phase separation speed were evaluated. From these tests, it was possible to obtain 100% oil removal using C/S = 9, t = 25 min, T = 50–60 ° C, demonstrating the viability of the evaluated systems.