Abstract:

Three aqueous dispersions of MgAl double hydroxide particles with different forms were prepared by a coprecipitation method. And then Pickering emulsions were prepared from them. The properties of the aqueous particle dispersions and the emulsions were studied. X-ray diffraction(XRD) and transmission electron microscope(TEM) characterizations indicate that the low crystallized particles dispersed in water in the manner of irregular shaped and loose structured particles with rough surfaces, while the well crystallized particles were the compact structured hexagonal platelets with smooth surfaces. Zeta potential measurements show that NaCl reduced the zeta potential of the three particles, resulting in particle flocculation in water. But the well crystallized particle dispersion flocculated in a higher salt concentration. The three double hydroxide particle/NaCl dispersions were used to prepare emulsions containing equal volumes of oil and water, respectively. The stability of the three emulsion systems was further compared. The results show that the stability of all emulsions was improved to some extent by the addition of NaCl. The emulsifying ability of the well crystallized particles appeared to be better than that of the low crystallized particles. For the low crystallized double hydroxides, the larger particles were better emulsion stabilizers than the smaller ones.

Key words: Double hydroxide, Dispersion, Pickering emulsion, Stability