科研之友
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摘要
Toluene/water Pickering emulsions based on fibrous palygorskite clay particles were stabilized by increasing the solid particle concentration. The emulsion droplet size reached to a plateau at 2 wt.%, suggesting the development of a three dimensional network in the emulsion. This was supported by measuring the steady state shear stress-shear rate of emulsions at different concentrations of palygorskite particles. Oscillatory theological measurements of storage modulus G%26apos; and loss modulus G%26quot; were then performed to verify that the emulsion system is strongly associated at concentrations greater than 2 wt.%, resulting in a viscoelastic film at the o/w interface. The role which palygorskite plays in emulsion stability by forming a three dimensional network is directly confirmed by observing the micro-morphology of palygorsldte particles in the emulsions using polarizing optical microscope (POM) and transmission electron microscopy (TEM). Without any chemical modification, palygorsldte fibers stabilized toluene/water Pickering emulsions over a wide range of pH (pH = 1.40 to 11.44). By adding HCl/NaOH, palygorskite clay-stabilized Pickering emulsions were successfully subjected to 5 emulsification-demulsification cycles, and all of the emulsions are stable for over 3 months in storage. Palygorskite has been demonstrated as an effective pH responsive emulsifier with long-term stability. The addition of NaCl leads to the aggregation and flocculation of the palygorskite particles, which increases the size of the emulsion droplets; however, stable toluene/water Pickering emulsions based on palygorskite clay can still be formed even at high NaCl concentrations.
- 出版日期2014-12
- 单位淮阴工学院
