De-emulsification performance and mechanism of β-CD reverse demulsifier for amphiphilic polymer oil in water (O/W) emulsion

Abstract In order to evaluate the performance and mechanism of de-emulsification for amphiphilic polymer produced oil in water (O/W) emulsion,the environmentally friendly β-cyclodextrin (β-CD) was chosen as a reverse demulsifier. Viscosity of amphiphilic polymer solution (APP4) and de-emulsification rate of the O/W emulsion were determined by rheometer and stability analyzer. The de-emulsification mechanism of β-CD was explored by measuring the interfacial tension, three-stage rheology and continuous phase viscosity. The results showed that the highest dewatering rate of the O/W emulsion with β-CD could reach 90 %. When the NaCl concentration increases, instability of the O/W emulsion increased. Temperature has little effect on demulsification. The reason for demulsification was that hydrophobic chain of APP4 is included by β-CD. The host-guest inclusion interaction could effectively disassemble the network structure of APP4, resulting in the large decrease of the structural viscosity. APP4 could not be adsorbed on oil–water interface, the droplets tended to grow up quickly. Thus, β-CD could be applied as an effective reverse demulsifier for O/W emulsion formed by amphiphilic polymer.