Emulsification studies

The initial emulsification studies employed a 1 L reactor vessel with baffles originally designed for fermentation processes. Subsequent studies were successively scaled up from 1 L to 3, 10, and 100 L. Variations due to differences in reactor configuration were minimized by utilizing geometrically similar reactors with approximately the same D/Tratio (i.e., 0.36-0.40). Maa and Hsu contended that separate experiments on the effect of the baffle area... 

The initial emulsification studies employed a 1-L reactor vessel with baf-... 

Toluene solubility and emulsification studies were also done with the SAAl and SAA2 products (described in Section 3.1.4.1). The SAAl product (ether-based run) completely dissolved in toluene and no residue was obtained during emulsification. This means that SAAl is a true amphiphilic material. The SAA2 product completely dissolved in toluene, but almost none of it formed a self-emulsion even in ammonia-water. 

The cleaning process proceeds by one of three primary mechanisms solubilization, emulsification, and roll-up [229]. In solubilization the oily phase partitions into surfactant micelles that desorb from the solid surface and diffuse into the bulk. As mentioned above, there is a body of theoretical work on solubilization [146, 147] and numerous experimental studies by a variety of spectroscopic techniques [143-145,230]. Emulsification involves the formation and removal of an emulsion at the oil-water interface the removal step may involve hydrodynamic as well as surface chemical forces. Emulsion formation is covered in Chapter XIV. In roll-up the surfactant reduces the contact angle of the liquid soil or the surface free energy of a solid particle aiding its detachment and subsequent removal by hydrodynamic forces. Adam and Stevenson s beautiful photographs illustrate roll-up of lanoline on wood fibers [231]. In order to achieve roll-up, one requires the surface free energies for soil detachment illustrated in Fig. XIII-14 to obey... 

The main performance characteristics of light-duty liquids or dishwash blends are soil emulsification and foaming. Figueroa-Raulli [73] published a comparative study of AOS vs. alkyl sulfates (AS), alcohol ether sulfates (AES), and linear alkylbenzenesulfonates (LAS) in light-duty liquid blends. The blends were evaluated for flash foam, the stability of foam under accumulating soil loads, and for the number of plates washed. Blend performance is expressed as a percentage of a dishwash reference standard. 

Studies of flow-induced coalescence are possible with the methods described here. Effects of flow conditions and emulsion properties, such as shear rate, initial droplet size, viscosity and type of surfactant can be investigated in detail. Recently developed, fast (3-10 s) [82, 83] PFG NMR methods of measuring droplet size distributions have provided nearly real-time droplet distribution curves during evolving flows such as emulsification [83], Studies of other destabilization mechanisms in emulsions such as creaming and flocculation can also be performed. 

Mahdi C, Oualid H, Fatiha A, Christian P (2010) Study on ultrasonically assisted emulsification and recovery of copper(II) from wastewater using an emulsion liquid membrane process. Ultrason Sonochem 17(2) 318-325... 

The nanoemulsion mean droplet sizes were much smaller than those obtained in other systems using polar oil mixtures (above 500 nm) [18]. The findings verify that the low-energy emulsification methods are valid not only for aliphatic [9,10,13, 75, 76, 79-81] and semipolar oils [82-84], as reported in most studies devoted to low-energy emulsification, but also for polar solvent-preformed polymer mixtures. These nanoemulsions show good kinetic stability at 25 °C over a period of at least 24 h,... 

Sadurm, N., Solans, C., Azemar, N. and Garci a-Celma, M.J. (2005) Studies on the formation of O/W nano-emulsions, by low-energy emulsification methods, suitable for pharmaceutical aplications. Emulsion polymerization initiation of polymerization in monomer droplets., 26, 438-445. 

The largest investment has been in desulfurization, and in most instances it has been proven that the sulfur compounds have been transformed into oxidized moieties, but the actual cleavage of the last C—S bond in most cases does not take place to the extent desired or to levels needed for implementing BDS. Other processes such as demetallization and upgrading are just starting to be studied. Collateral technologies, for gas treatment and reducing viscosity by emulsification ( in well treatments) are commercially available. 

A well-studied example of a bioemulsifier is emulsan, a cell surface-exposed molecule that allows Acinetobacter calcoaceticus RAG-1 to attach to crude oil droplets [123]. Upon depletion of the short-chain alkanes utilised by this strain, the emulsan molecules were released from the bacterial surface, thereby allowing the cells to leave the oil droplet and to find a new substrate. Important positive side-effects of this mechanism seem to be that the remaining emulsan hydrophilises the droplet and prevents both the reattachment of A. calcoaceticus RAG-1 and the coalescence of the used oil droplet with other droplets that still contain unexploited alkanes. Bredholt et al. [124] studied the oil-emulsifying activity of Rhodococcus sp. strain 094. When exposed to inducers of crude-oil emulsification, the cells developed a strongly hydrophobic character, which was rapidly lost when crude-oil emulsification started. This indicated that the components responsible for the formation of cell-surface hydrophobi-city acted as emulsion stabilisers after release from the cells. 

Study of the eflSciency of packed columns in liquid-liquid extraction has shown that spontaneous interfacial turbulence or emulsification can increase mass-transfer rates by as much as three times when, for example, acetone is extracted from water to an organic solvent (84, 85). Another factor which may be important for flow over packing has been studied by Ratcliff and Reid (86). In the transfer of benzene into water, studied with a laminar spherical film of water flowing over a single sphere immersed in benzene, they found that in experiments where the interface was clean... 

It is noteworthy that this formulation is different from fluorosilicones. Fluorosili-cones are fluorine-containing silicone oils with a 1.35 g/cm density. Their poor tolerance in animals and men was demonstrated by experimental studies [45,46] ocular hypertonia, keratopathy, early emulsification and severe inflammatory reactions. They cannot therefore be used as a heavy internal tamponade product. 

In the clinical study, perioperative complications were highlighted by two cases of early and unexplained emulsification, impairing fundus visualisation but not precluding reapplication. Post-operative complications were emulsification in seven case, including one very severe one. No corneal dystrophy and no ocular hypertonia were reported. 

On the basis of the results, it appears that heavy silicone oil Oxane Hd , the first formulation of this type on the market, as a temporary internal tamponade is equally tolerated as standard silicone oil in the surgical treatment of complex retinal detachment. It does not pose any emulsification or major fragmentation problem, as encountered with other heavier than water products. Its effectiveness on inferior and posterior dehiscence tamponade appears to be very effective to currently available anatomical results. Oxane Hd , moreover, presents in this context a real benefit in the treatment of complex retinal detachment [48]. Retinopexy quality and the absence of residual subretinal fluid in internal tamponade of inferior lesions, extensive inferior retinectomies in particular, may reduce the risk of recurrence of complex retinal detachment by PVR. More extensive studies are now in course to see the limits of Oxane Hd in comparison with new analogues such as Densiron 68 , which has been marketed recently. 

Chen [8] studied mixtures of the pure surfactants Ci2(EO)4 and sodium dodecyl sulfate (SDS) at 30 °C. At this temperature the former is a liquid which does not dissolve in water (see Fig. 3), and the latter is a solid. The SDS was doubly recrystallized from ethanol to remove n-dodecanol and other impurities. The solubility of SDS in pure Ci2(EO)4 at 30 °C was found to be approximately 9 wt. %. When small drops of an 8 wt. % mixture were injected into water at 30 °C, complete dissolution was observed, the time required being a linear function of the square root of initial drop radius. For instance, a drop having an initial radius of 70 (xm required approximately 100 s to dissolve, significantly more than the 16 s cited above for a slightly larger drop of pure Ci2(EO)6. Behavior was similar to that of nonionic mixtures below their cloud points discussed previously in that most of the drop dissolved rapidly, but the final small volume dissolved rather slowly with some observable emulsification. 

During the studies of phase behaviour two types of liquid crystalline phases were identified. LC material was viscous and exhibited intense "white" birefingence. material was apparently homogeneous but of low viscosity and exhibited "multi-coloured" birefringence. The liquid crystalline phases observed in the equilibrium studies of surfactant concentrations up to 25 are unlikely to take part in the self-emulsification process due to the presence of two-phase regions between L2 and liquid crystalline phases however, LC material may account for the improved stability of emulsions formed by 25 surfactant systems (Table II). Figure 4c indicates that by increasing the surfactant concentration to 30 the... 

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