A Further Step in the Development of Oil-in-Water Emulsions Formulated with a Mixture of Green Solvents

Abstract

10Finding alternatives to traditional organic solvents is one area in green chemistry, 11 which has generated great interest in recent years. This work provides new possibilities 12 for the preparation of ecological oil-in-water (O/W) emulsions. Model emulsions that 13 may be used as matrices for agrochemical formulations have been investigated. 14 Specifically, this paper deals with O/W emulsions formulated with a mixture of green 15 solvents and a polyoxyethylene glycerol ester as emulsifier. Firstly, an optimum ratio of 16 solvents was found, after which the droplet size distribution, physical stability and flow 17 properties of emulsions obtained using two rotor-stator devices (toothed geometry vs 18 emulsor screen) and two high-pressure homogenizers (high pressure valve 19 homogenizer, HPVH, vs Microfluidizer) were compared using several processing 20 variables. Considering its low Turbiscan stability index and the absence of 21 coalescence, 75/25 (N,N-dimethyldecanamide/α-pinene) was the optimum ratio of 22 biosolvents. All samples showed droplet sizes with submicron diameters (both 23 volumetric and Sauter means). However, both high-pressure homogenizers yielded 24 smaller droplet sizes than rotor-stators. The combined use of multiple light scattering, 25Rheology and Laser Diffraction allowed the destabilisation processes of emulsions to 26 be monitored. The results obtained demonstrated that the emulsions prepared with a 27 Y-shaped Microfluidizer at 15000 psi (103.4 MPa) and 1-pass exhibited the highest 28 physical stability. 29

Progressing Towards the Sustainable Development of Cream Formulations

“…It is possible to find a relation between K and n values. K results, for samples with different n values, may be properly compared since a modified Ostwald de Waele equation is used [ 6 , 60 , 62 , 64 , 65 ].…”

Microfluidic Production of Multiple Emulsions

“…Emulsions are dispersion of stabilised liquids within a continuous immiscible liquid, and has long been used in a verity of applications including production of pharmaceuticals [ 1 , 2 , 3 ], cosmetics [ 4 ], foods [ 5 ], electronics [ 6 ], and energy-related [ 7 , 8 , 9 , 10 ]. Emulsions can be fabricated as two-phase dispersions, namely simple emulsions, such as oil-in-water or water-in-oil [ 11 , 12 , 13 ] or complex multi-phase dispersions known as multiple emulsions, consisting of larger drops containing single and multiple inner compartments [ 14 , 15 , 16 , 17 ]. Multiple emulsions are often the intermediate products in the synthesis of microcapsules used for protecting actives from chemical degradation or evaporation [ 18 , 19 , 20 ] and for delayed/triggered release [ 21 , 22 , 23 ].…”

A comparison of microfluidization and sonication to obtain lemongrass submicron emulsions. Effect of diutan gum concentration as stabilizer

“…It creates an enormous shearing action, which can produce very fine emulsions. Some researchers claim that microfluidization is superior than traditional emulsifying homogenizers because the DSD obtained are narrower and smaller 4,5 . However, the use of microfluidizers is sometimes related to the over-processing phenomenon, which provokes the occurrence of re-coalescence 6 .…”