Assessment and Application of Modified Cationic Polyvinyl Alcohol Emulsifiers in Bitumen Emulsions

In this work, a series of emulsifiers were prepared by changing the molar ratio of polyvinyl alcohol (PVA) to the long chain quaternary ammonium salt (A0). The emulsifiers were characterised by FTIR and 1HNMR. The stability of the emulsions was checked and evaluated by determining the phase separation and by UV-Vis spectrophotometry. The emulsion stability increased with increasing emulsifier concentration, which was mainly due to the reduced droplet size and increased viscosity of the emulsions. Stability was also dependent on pH. At pH values between 5 to 3, stability was increased, but at further decreasing pH values, the emulsion became unstable or the emulsion separated. This could be mainly because the excess of positive ions compresses the double electron layer. The experimental results showed that PVA as a macromolecular matrix material has a great application potential for the emulsification process.

Comparative Study of Cleansing Action of Some Detergents Available in Nepalese Market

Detergents commercially available in the Nepalese market were studied and several parameters such as surface tension, pH, critical micelle concentration, foaming stability test, hard water test, emulsions stability test were performed. Different medium such as ground water (G.W.), tap water (T.W.), distilled water (D.W.) and 5% ethanol in distilled water were selected for this study. The decrease in surface tension and critical micelle concentration (CMC) in ground water, tap water, distilled water and 5% ethanol in distilled water, ease of cleansing action of the detergents in this medium have been found of the following order: 5% ethanol in distilled water > distilled water (D.W.) > tap water (T.W.) > ground water (G.W.). Among the four detergents, the D1 have shown the least surface tension, CMC value, foam collapsing time, the weight of scum formed when treated with hard water. And maximum emulsion stability of the detergent D1 determines good quality detergent.

Cinnamon Essential Oil Nanocellulose-Based Pickering Emulsions: Processing Parameters Effect on Their Formation, Stabilization, and Antimicrobial Activity

This work aimed to prepare nanocellulose-based Pickering emulsions using cinnamon essential oil. Different formulations were investigated by varying the preparation time, homogenization speed, oil and nanocellulose concentration, and morphology. The emulsions were first characterized by droplet size, morphologies, and storage stability. The Design of Experiments (DoE) was used to evaluate the parameter’s effects on the emulsions’ stability, and the emulsions with optimum particle size and stability were evaluated by antimicrobial activity. The more stable emulsions required higher energy in the system to obtain efficient emulsification. The cellulose nanocrystal (CNC) emulsions showed a 30% oil volume as a constant to obtain a low creaming index (34.4% and 42.8%) and zeta potential values around −29 mV, indicating an electrostatic stabilization. The cellulose nanofiber (CNF) emulsions showed 100% stability after a month using a 20% oil volume as a constant and Zeta potential values around −15 mV, indicating a steric stabilization. CNF-emulsions’ inhibition halos for Bacilus subtilis were 30.1 ± 3.7% smaller than those found in CNC-emulsions (65 ± 2.9 mm), while Pseudomonasaeruginosas almost do not present differences in the inhibition halos. These results suggest that the nanocellulose morphology may promote a regulation on the EO migration to the medium, as well that this migration ratio does not affect the bacteria.

An Innovative Miniature Pulsating Emulsification Device: Flow Characterization and Measurement of Emulsion Stability

The aim of this study is the development of an emulsification device for two immiscible liquids with a total volume of approximately 3 mL. The heart of the device is a piston, with an aluminum plate fixed at its tip, which moves periodically up and down inside a rectangular cell. The plate geometry (uniform or non-uniform height) affects significantly both the emulsions stability and the size of the droplets of the prepared emulsions. Five parameters are examined during testing (surfactant type, surfactant concentration, proportion of immiscible liquids, piston stroke frequency, duration of emulsification) and all of them appear to have an important role in the resulting droplet size distribution. A macroscopic theoretical model is developed for the determination of the main hydrodynamic parameters of the innovative device. It is shown that the non-uniform height plate achieves higher shear rates when compared to the uniform height plate because of the smaller gap between the plate and the cell walls. However, the benefits of the higher shear rate are overturned by the larger effective breakage time encountered in the uniform height plate resulting from the larger surface area of its sides. The results of the emulsification experiments are analyzed using the parameter values derived by the developed model.