DETERMINATION OF THE ANGLE OF SELECTIVE WETTING OF POLYDISPERSE ISOMORPHIC SOLID PARTICLES

Construction, Penza, e-mail: nushtaeva.alla@yandex.ru The main characteristic of selective wetting of solid particles is the angle θ ow that a single particle forms at contact with the water-oil interface. A hydrophilic-lipophilic ratio HLR is associated with the angle θ ow and it is also a wetting characteristic. The wetting heat of solid particles of insoluble dry powder with water ΔH w and the wetting heat with oil ΔH o were measured by the calorimetric method in this work. By the values ΔH w and ΔH o the hydrophilic-lipophilic ratio was determined as the ratio of the wetting heats, and the contact angle θ ow was calcu-lated. The polydisperse isomorphic solid particles of different nature were investigated: lamellar microtalc particles Talcon T-20 and particles of food solid emulsifiers. As food emulsifiers, powders of plant origin were used: ground cinnamon, ground ginger, mustard powder, ground nutmeg. In the case of talc particles of micrometric size, the value of the contact angle θ ow was equal to 97 ° (and HLR <1, respectively) for the water – olive oil interface and it was equal to 85 ° (HLR > 1) for the water – hexane interface. In the case of food powders, the values of the contact angles θ ow were in the range of 56–66 ° (and HLR > 1, respectively). All the values of HLR and the contact angle θow are in good agreement with the results of using these particles as stabilizers of Pickering emulsions. When the ratio HLR was greater than 1, stable direct emulsions were formed using food powders or talc in the case of using a saturated hydrocarbon as the non-polar phase. When the ratio HLR is less than 1, stable reverse emulsions were formed (from talc particles in the case of using olive oil