The effect of lipophilicity of corrosion bacteria on the stability of crude oil Pickering emulsions in produced water

A major environmental challenge often encountered during the production of crude oil is the formation of extremely stable oil-in-water emulsions in the effluent. The stability of these emulsions is so high that it reduces the efficiency of treatment methods. Among different parameters, the absorption of corrosion bacteria (CB) on the surfaces of crude oil droplets even more increases the emulsions stability. Therefore, in this study the lipophilicity and surface charge of three types of CBs (SRB, APB and IRB) with respect to three types of crude oil samples (paraffinic, aromatic and naphthenic) were investigated experimentally. The results revealed that based on the Langmuir adsorption isotherm a portion of CBs are adsorbed on the surface of crude oil droplets as monolayer, while another portion adheres to this monolayer leading to form a multilayer CBs. On the other hand, it was showed that the nature and chemical characteristics of droplet's organic phase affects the reversibility of the adsorbed layer of CBs. The CBs adsorption on the surface of paraffinic crude oil droplets was determined to be completely irreversible, while those of aromatic and naphthenic oil droplets were semi-reversible and reversible, respectively. The lipophilicity of SRB cells was decreased in acidic and alkaline media while it was maximum at pH = 5 corresponding to the critical zeta potential (zeta C approximate to-15 mV).