W/O Emulsion Destabilization and Release of a Polysaccharide Entrapped in the Droplets

This study was conducted as part of European project VEGEPHY to develop a product for the crop protection purposes. It concerns first the destabilization of a W/O emulsion containing water droplets in which the polysaccharide carboxymethylcellulose (CMC) is trapped, the droplets being dispersed in a vegetable oil made of rapeseed methyl ester. Polyglycerolpolyricinoleate (PGPR) is used as surfactant and glycerol is added to enhance the dispersion of the CMC. The second part is dealing with the study of the release and dilution of the CMC obtained by dilution of the destabilized emulsion in water in order to obtain the required final amount of CMC for practical purposes. The destabilization of the emulsion by the demulsifier (cynthiorex PMH 1125) has been followed by differential scanning calorimetry (DSC) that permits by studying the freezing of the dispersed water to detect the presence of bulk water. The release and dilution in water of the CMC versus time was followed and quantified by measuring the conductivity of the sample. The release kinetic was modeled using a first-order empirical model. The results showed that the release process of the W/O emulsion depends on the concentration of the demulsifier, on the stirring rate, and on the temperature. The optimum amount of the non-ionic surfactant was found to be 10% and the full release of the CMC has been obtained in 600 seconds.