Demulsification of W/O emulsions using highly branched polymer demulsifier with 2,6-naphthalenedicarboxylate as centronucleus

A highly branched PNDC demulsifier with 2,6-naphthalenedicarboxylate as centronucleus was prepared by an efficient “one-pot” strategy. The product was characterized by FT-IR, 1 H-NMR, and TGA. The bottle test was performed to explore the effect of temperature, settling time, pH value, and concentration on the demulsification efficiency (DE). The DE reached an optimal value of 94.63% when the concentration of PNDC, settling time and operated temperature were 100 mg/L, 60 min and 70°C, respectively. Also, the DE could reach 91.58% when the concentration was only 20 mg/L at the same conditions. It showed that PNDC had an excellent performance in W/O emulsions with an extremely low concentration. Especially, PNDC could be used over a wide pH range (4–12) and high salinities, indicating that it had a good salt, acid and alkaline tolerance. In addition, the interfacial tension (IFT), surface tension (SFT), elastic modulus and micrograph analysis were carried out to investigate the possible mechanism. This work provides a highly branched demulsifier with high DE for the demulsification of stable W/O emulsions.