Title:Research Progress on Improving the Stability of Paraffin Emulsion:
A Mini-Review
Volume: 15
Issue: 3
Author(s): Yu Liang*, Endong Xia, Haiyan Li, Zidong Wang and Shoutao Ma
Affiliation:
- Daqing Petrochemical Research Center, Petrochemical Research Institute of PetroChina Company Limited,
Daqing 163714, Heilongjiang, P.R. China
Keywords:
Paraffin, paraffin emulsion, emulsification stability mechanism, interface film, emulsion destabilization, Brownian motion.
Abstract: Paraffin emulsion is a highly dispersed, thermodynamically unstable system.
Emulsifiers play a key role in promoting emulsion formation and improving emulsion
stability. However, a single emulsifier has limitations in maintaining emulsion stability,
usually, it is necessary to compound more than two emulsifiers or add other additives to
make the paraffin emulsion have better stability. Therefore, how to keep paraffin emulsion
high dispersibility and stability for a long time are the problems that the majority of
researchers have been concerned about. This paper expounded the instability mechanism
of paraffin wax emulsion. The process of paraffin emulsion destabilization is the process
of gradually reducing the free energy of the system and the interaction force between
emulsion droplets determines the speed of emulsion destabilization. Sedimentation and
stratification, flocculation, coalescence, and Ostwald Ripening were the main factors
leading to paraffin instability; the prevention and improvement methods are proposed for
the above four mechanisms. From the instability mechanism, the factors affecting the
stability of paraffin emulsion mainly include the mechanical strength and film elasticity
of the interface film, the interfacial charge or obstruction between the emulsion droplets,
the appropriate system viscosity, and the uniform droplet size distribution will affect the
stability of the paraffin emulsion. Through literature research, several methods to improve
the stability of paraffin emulsion were summarized. Polar paraffin has good emulsifying
properties, compounding with paraffin can not only reduce the amount of emulsifier
but also enhance the stability of paraffin emulsion, adding thickeners can reduce the
Brownian motion of droplets and improve the chemical and mechanical stability of wax
emulsions, the addition of ionic surfactants can reduce the diffusion rate of the dispersed
phase, the addition of inorganic salts can make the emulsion droplets generate strong repulsion
when they are close to each other, and improve the stability of the emulsion, the
addition of small molecular alcohols can improve the flexibility of the oil-water interface
film properties, reduce the surface tension coefficient of the emulsion, and increase the
stability of the paraffin emulsion. This paper can provide a theoretical reference for the
research on the stability of paraffin emulsion.