Influence of cetyltrimethylammonium bromide and hydroxide ions on the interfacial tension and stability of emulsions of dodecane in aqueous silicate solutions

Study on the relationships between the oil HLB value and emulsion stabilization

In order to study the relationship between the HLB value of oil and emulsion stabilization, the optimal formation of emulsification system was determined, and then, the properties of emulsion, such as particle size, stability, interfacial tension and zeta potential, were tested by laser particle analyzer, stability analyzer, and interfacial tensiometer. Experimental results showed that the optimal ratio of emulsification was Tween 80 : Span 80 = 5 : 5. Meanwhile, when the HLB value of the emulsification system was close to that of oil, the emulsion exhibited the best stability. This phenomenon is due to the fact that when the HLB values are close, the surfactant molecules are arranged more closely on the oil-water interface, leading to smaller sized emulsion droplet, which is conducive to emulsion stability. This study provides new insights into the effective adjustment of emulsion stability.

Boosted photocatalytic performance of OVs-rich BiVO4 hollow microsphere self-assembled with the assistance of SDBS

In this study, monoclinic phase bismuth vanadate (BiOV₄) photocatalyst with unique hollow microsphere morphology was successfully prepared by a hydrothermal method in the existence of sodium dodecyl benzene sulfonate (SDBS). The prepared photocatalysts were characterized by X-ray diffraction (XRD), scanning electron (SEM) and X-ray photoelectron spectrometer (XPS) and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). Experimental results show that SDBS definitely changes the microstructure of BiVO₄, which is allocated to the template role of SDBS in the preparation process. Moreover, the hydrothermal treatment time is also of crucial importance in affecting the structure and morphology of the photocatalysts, and the optimal hydrothermal treatment time for the formation of hollow microsphere is 24 h. Furthermore, the feasible growth mechanism for hollow microsphere was elaborated. Enriched oxygen vacancies (OVs) are introduced into BiOV₄ prepared with SDBS, largely elevating the separation efficiency of photo-generated charges. Under visible light irradiation, the photocatalytic activities of BiOV₄ for destruction of rhodamine (RhB) were evaluated. The photocatalytic degradation rate constant of RhB on the 3SBVO is 2.23 times of that on the blank BiOV₄ as the mass ratio of SDBS/BiOV₄ is 3 %. Photocatalytic degradation mechanism of BiVO₄ toward detoxification of organic pollutants was presented.

Perspectives in the stability of emulsion explosive

This review explores the stability of emulsion explosive, through summarizing its instability reason, stability mechanism, affecting factors, improvement ways and evaluation methods. The emulsion explosive can be recognized as highly concentrated emulsion due to the volume fraction of dispersed phase exceed 74%. The polydispersity, deformation of compassed droplets and the high content of AN in dispersed phase should be considered for the stability of emulsion explosive. The coalescence is one of the important factor for the instability of emulsion explosive as the droplets bound to each other tightly, together with that, the crystallization of AN in dispersed droplets will occur. This process will further decrease the stability of emulsion explosive. Interfacial tension, the strength of interfacial film and electrical properties of droplets are the important mechanism for preparation and stability of emulsion explosive, among the three, the effect of the strength of interfacial film is most important, and the greater the strength of the interfacial film, the more stable the emulsion explosive. The stability of emulsion explosive will be affected by the emulsifier's structure, the viscosity and polarity of oil, the crystallization point of AN and the nature of matrix, in which, it is important to pay attention to the influence of emulsifier structure because adjusting emulsifier structure is a key channel to improve the stability of emulsion explosive. Besides that, the targeted methods to improve the stability of different emulsion explosive, such as bulk emulsion explosive, packaged emulsion explosive and powdery emulsion explosive, were concluded and established. Finally, we proposed some effective methods for evaluating and predicting stability of emulsion explosive. These results will facilitate the further development of the researches in the mechanism and improvement approach of stability, as well as it will also provide effective technical support for exploring the stability of other similar highly concentrated emulsions.