Contents lists available at ScienceDirect Journal of Water Process Engineering journal homepage: www.elsevier.com/locate/jwpe Infuence of the use of surfactants in the treatment of produced water by ceramic membranes S.E. Weschenfelder a,b, ⁎ , M.J.C. Fonseca b , B.R.S. Costa a , C.P. Borges b a Petrobras Research Center, Rio de Janeiro, Brazil b COPPE/Chemical Engineering Program, Federal University of Rio de Janeiro, Brazil ARTICLE INFO Keywords: Produced water Surfactants Enhanced oil recovery Ceramic membranes Treatment ABSTRACT Surfactant-enhanced oil recovery is a method used to augment residual oil extraction from reservoirsHowever, this kind of procedure can produce stable emulsions of water/oil and oil/water, making the conventional treatment of the produced water more difcult. This study evaluates the performance of ultrafltration process using ceramic membranes for produced water treatment containing the cationic surfactant Dodecyltrimethylammonium bromide (DTAB). To better understand the process, the efect of DTAB and sodium chloride (NaCl) on interfacial properties of oil/water and oil/water/membrane, such as surface tension, mem- brane wetting, zeta potential and adhesion map were investigated. It was observed that the surfactant facilitates the oil phase adhesion to the membrane surface, causing a permeate fux reduction. On the other hand, the presence of NaCl in the oily emulsion containing DTAB lead to a permeate fux increase, which indicated that ionic strength modifes the interaction between the oil phase and the membrane surface. Considering the high salinity of the produced water, it is possible to imply that the presence of surfactant can contribute to treatment by ultrafltration process. Independent of surfactant presence in produced water, the oil and grease (C OG ) content in the permeate stream was consistently lower than 5 mg/L. 1. Introduction Primary and secondary recovery procedures are capable of re- covering only about 35% of the oil contained in the reservoir [1]. In order to extract residual oil in mature reservoirs, enhanced oil recovery (EOR) methods are applied, among them chemical addition methods can be highlighted. The purpose of chemicals is to modify the interac- tion between the fuid injected and the fuid contained in the reservoir with the rock. Three chemical categories are usually applied - polymers, surfactants and alkaline products - either together or separately [2]. Injection of surfactant solutions has proven to be very efcient in in- creasing the degree of oil recovery. It its caused by the amphiphilic characteristic of the surfactant, i.e., each molecule has two functional groups, a polar group (hydrophilic) and a nonpolar group (hydro- phobic), which are capable of interacting with both water and oil, leading to an improvement in the sweep efciency and thus the re- covery factor. The hydrophobic group is generally comprised of a long hydrocarbon chain (C8 and C18), which may be branched or not, while the hydrophilic group is formed by moieties such as carboxylates, sul- fates, sulfonates (anionic), alcohols (nonionic) and quaternary ammo- nium salts (cationic) [3]. Due to this structure, the surfactant can be used to emulsify the oil by the strong reduction of interfacial tension (IFT) or to alter the oil wettability in the reservoir [4]. According to Gary and Handwerk [5], in presence of dissolved salt, the surfactants accumulate at the interface oil/water, intensifying formation of an adsorbed flm and IFT reduction. Depending on the properties of the crude oil (API gravity, viscosity, sulfur content, salts, metals, among others), the structure of adsorbed surfactant flm can vary signifcantly. The molecular packing, surface viscosity, surface elasticity and surface charge of the adsorbed flm are key parameters that determine several phenomena, such as the coalescence of emulsion droplets as well as the migration of oil droplets in porous media [3]. Diferent surfactants have been investigated with the purpose of altering the wettability of the reservoir rock and, consequently, in- creasing the oil recovery factor [6]. Among these products, the cationics ones have the advantage of having the same surface charge as carbo- nate minerals. Standnes and Austad [7] showed that cationic surfac- tants, such as Dodecyltrimethylammonium Bromide (DTAB), are highly efcient for this purpose, being able to recover approximately 70% of original oil in place. According to the authors, this high rate could be related to the same surface charge presented by the carbonate minerals and the surfactant. Despite the many advantages related to advanced https://doi.org/10.1016/j.jwpe.2019.100955 Received 17 July 2019; Accepted 8 September 2019 ⁎ Corresponding author at: Petrobras Research Center, Rio de Janeiro, Brazil. E-mail address: silvioweschenfelder@petrobras.com.br (S.E. Weschenfelder). Journal of Water Process Engineering 32 (2019) 100955 2214-7144/ © 2019 Elsevier Ltd. All rights reserved. T