Effect of Water/Decane Ratios and Salt on the Stability, Rheology, and Interfacial Tension of Water/Decane Emulsions

This study investigates the effects of water/decane ratios and sodium chloride (NaCl) salt (1%-4%) on the water/decane emulsions with focus on the understanding of their stability, droplet sizes, rheology, and interfacial phenomena. Experimental results reveal that water/decane ratio has a great impact on the stability of water/decane emulsions. Reducing the water volume and increasing decane volume reduce the stability of water/decane emulsions. The instability is more pronounced at equal water/decane ratio. Conversely, the addition of NaCl modified emulsion stability. Increasing the NaCl concentration in the formed emulsions resulted in improved stability. Water/decane ratios exhibited different droplet sizes of the emulsions which have linkage to their stability. However, the presence of NaCl salt in the emulsion rendered the droplet sizes smaller, especially when the salt concentration increases. Rheological measurements demonstrated that water/decane ratios influenced the viscoelastic behavior of the emulsions. Moreover, increasing the NaCl concentrations has a positive impact on the elastic modulus of the water/decane emulsion. The interfacial tension (IFT) measurements revealed that the water/decane without NaCl/surfactant and water/decane-surfactant devoid of NaCl salt have IFT values of 46.17 and 0.241 mN/m, respectively while water/decane-surfactant containing different NaCl concentration possessed IFT values within 0.25-0.293 mN/m. The outcomes of this research would be an initial step in understanding the emulsion formation in many industrial processes.