CO2-responsive zwitterionic copolymer for effective emulsification and facile demulsification of crude heavy oil

Viscosity reduction by emulsification would greatly facilitate the exploitation and pipelining transportation of heavy oil, as well as oil sands/sludge washing. However, the final demulsification process to achieve separation of oil and water is tricky. Therefore, developing smart emulsifiers that can be switched on demand to achieve both effective emulsification and facile demulsification in subsequent oil/water separation process would be of great significance to the practical applications. In this paper, a zwitterionic copolymer emulsifier comprising acrylamide (AM), 2-(diethylamino) ethyl methacrylate (DEAEMA) and 3-[dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]azaniumyl]propane-1-sulfonate (SBMA) was prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization for better control of the molecular weight, exhibiting good salt resistance and fast CO2-responsiveness. The prepared copolymer can efficiently emulsify heavy crude oil with a viscosity reduction rate up to 98.6% in highly mineralized water. While in the presence of CO2, the formed heavy oil/water emulsions can be rapidly broken to obtain oil-water two phases. Compared with traditional demulsification methods, the CO2-responsive strategy presented in this work can achieve a lower oil content in water (1.4%) after separation. Furthermore, the copolymer can also be applied to effectively emulsify and clean oily sludge. The CO2-responsive zwitterionic copolymer emulsifier demonstrated great potential in various engineering applications including exploitation and pipelining transportation of heavy oil, and oil sands/sludge washing, facilitating reduction of water pollution and energy saving. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

A CO2-responsive zwitterionic copolymer emulsifier was prepared for efficient emulsification and rapid phase separation of heavy oil/water emulsions. It showed great potential in various engineering applications including heavy oil exploitation and oil sands washing, which could contribute to reducing water pollution.