Liquid paraffin/water emulsion stabilized by synergistic action of bi- metal hydroxide and modified sodium alginate

Mg /Al bi- metal hydroxide( LDH) was prepared via unsteady co- precipitation method.Hydrophobic cholesterol( Chol) was grafted onto sodium alginate( Alg) via coupling esterification to form an amphiphilic modified sodium alginate( Alg- Chol). Then the Alg- Chol and LDH was blended to be an emulsifier for synergistic stabilization of liquid paraffin /water emulsion. The LDH,Alg- Chol,LDH /Alg- Chol water dispersion,as well as liquid paraffin /water emulsion were characterized by FTIR,1HNMR,TEM,DLS,contact angle measurement and optical microscope et al. Results from TEM and DLS showed that the average size of LDH is 159 nm,and the dispersion coefficient is 0. 267. Results from FTIR and1HNMR showed that the hydrophobic Chol group has been successfully grafted onto the side chain of Alg. With different NaCl concentration,the contact angle of LDH /Alg- Chol water dispersion system on paraffin plate is near to 90°,which denotes that the wetting power of LDH /Alg- Chol is quite high and is beneficial to upgrade the stability of the emulsion. As the concentration of NaCl increases,the particle size increases from 101. 7 μm to121. 8 μm,then gradually drops to 58. 1 μm. This is due to the LDH /Alg- Chol self- assembles to form an interface film on the surface of the liquid particles of the emulsion and the particle size of the emulsion is affected by the change of amount of LDH /Alg- Chol adsorbed on the oil /water interface.