| Summary: | 碩士 === 國立中興大學 === 化學工程學系所 === 105 === The aim of this study is to prepare the modified MMT by the adsorption of oil soluble cationic surfactant (i.e., dimethyl distearyl ammonium chloride, DMDSAC) on MMT surface for Pickering emulsions to obtain O/W or W/O emulsions. The DMDSAC surfactant adsorbed on MMT can be divided into two systems. System (I) is the double-side surface of MMT adsorbed with DMDSAC. System (II) is the single-side surface of MMT adsorbed with DMDSAC. Water was adopted as the aqueous phase, and toluene was chosen as the oil phase in this study. The effects of the water to oil volume ratio (W/T), DMDSAC to MMT weight ratio (D/M), and the loading of MMT on the droplet size and stability of the emulsions were also investigated.
In system (I), the modification of MMT was done by using MMT clay and adsorbed with DMDSAC in water/ethanol solution. With the increase loading of DMDSAC, the decrease of char yield from TGA and increase of the layer spacing from XRD were observed. For 1 g MMT dispersed in the water/ethanol solution, the DMDSAC ethanol solution with the weight range of 0.04 g to 0.67 g was used, the adsorption of DMDSAC on MMT increased from the 0.028 g to 0.620 g at the same time, the char yield decreased from 89.8% to 57.2% and the layer spacing increased from 1.45 nm to 2.82 nm. Pickering emulsions were prepared by modified MMTs which were used as emulsifier for water and toluene. As the D/M ratio increased to above 0.33, the W/O emulsions were obtained. With the loading of the modified MMT increased from 0.02 w/v% to 0.10 w/v%, the diameter of emulsions decreased from 204.3 μm to 51.2 μm.
In system (II), Pickering emulsions were prepared by intense mixing of MMT dispersing in water and DMDSAC dissolved in toluene. This type of emulsions were W/O. With the D/M ratio increases from 0.25 to 0.67, the diameter of emulsion decreases from 109.6 μm to 84.0 μm at W/T ratio 2/2. When the W/T ratios are 2/2, 1/2 and 0.5/2, the diameter of emulsions are 122.0, 120.6 and 93.8 μm respectively. As the W/T ratio decreases, the diameter of emulsion decreases. With the loading of MMT increases from 0.02 wt% to 0.10 wt%, the diameter of emulsion decreases from 226.1 μm to 122.5 μm at D/M ratio 0.25.
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