Petroleum, emulsions with light

Hallworth and Carless (1 ) discuss several possibilities for the effect of light liquid paraffin on the stability of emulsions with light petroleum or chlorobenzene as the main components. They seem to prefer an explanation previously advanced by them and several other authors for the effect of fatty alcohol, namely that the increased stability is due to the formation of an interfacial complex between the additive and sodium hexadecyl sulphate. The condenced mixed film will resist coalescence primarily by virtue of its rheological properties. With mixed films of the present type, the importance of the film viscoelasticity lies in its ability to maintain electrical repulsion between approaching droplets by preventing lateral displacement of the adsorbed ions. The effective paraffinic oil has chains at least as long as those of the alkyl sulphate and will be associated by van der Waals forces with the hydrocarbon chain of the alkyl sulphate at the interface. 

The filtrate from the nutsch filter enters receptacle 9, and from there into vapour-heted tank 10 for distilling chlorobenzene in vacuum (chlorobenzene is sent back to synthesis). The cooled oily residue from the tank is sent into nutsch filter 13 to be separated into crystals (raw phosphonitrilechloride trimer) and oily liquid (phosphonitrilechloride oligomers). Trimer crystals are sent into collector 14 (it is also filled with light petroleum, which does not dissolve oily oligomers). The emulsion formed in the collector is sent into extractor 16. A temperature equal to the boiling point of light petroleum is maintained in this apparatus. 

This pressure extraction system is completely hermetically sealed. Therefore it excludes loss of gas and light petroleum fractions. The pressure extraction system allows for petroleum preparation at a central processing station for oils from several oil wells located in an area up to a 100-km radius. However, long distances for petroleum transport can lead to the creation of stable emulsions. With high humidity of the petroleum, this can lead to an increase in operations and transport costs. Nevertheless, it is one of the promising systems of petroleum extraction that is widely applied. 

Light petroleum is volatile and losses of solvent occur by evaporation during measurements of optical density in spectrophotometric cells. This loss can be reduced if stoppered cells are used. Soapy emulsions are more easily broken down with light petroleum than with ether. No change of solvent is required if light petroleum can be used throughout the analytical process. 

Heat 5 to 10 g of emulsion, accurately weighed, with 20 ml of a mixture of equal parts of concentrated hydrochloric acid and water, on a water-bath until the emulsion is destroyed. Cool, transfer to a separator and extract three times with large quantities of ether. Wash the mixed ethers, evaporate, dry and weigh. After weighing the flask and contents, wash out the oil with light petroleum, dry and weigh the flask and any residue which may have been extracted from non-fatty material by the ether. The difference in weight obtained represents the oil present in the quantity taken. 

Weigh 0 5 to 10 g of emulsion, add anhydrous sodium sulphate in considerable excess, sufficient so that on massing the product is quite dry, powdery and free from clots. Transfer the whole to a Soxhlet thimble and extract with light petroleum (b.p. 40° to 60°) for two hours. Evaporate the solvent, dry and weigh the oil. 

Effect of hexadecane as additive In a series of papers Hallworth and Carless (7,8,9,TO) have investigated the effect of the nature oT the internal phase on the stability of oil in water emulsions as well as the effect of addition of long chain fatty alcohols with sodium dodecyl sulphate or sodium hexadecyl sulphate as the ionic emulsifier. They found that light petroleum and chlorobenzene emulsions prepared only with sodium hexadecyl sulphate were much less stable than those produced using the longer chain paraffins, white spirit and light liquid paraffins. 

Some terms are used in other ways by other researchers, or in other countries, and may have legal definitions different from those given here. The distinctions drawn among light, heavy, extra-heavy, and bituminous crude oils were made on the basis of United Nations Institute for Training and Research (UNITAR)-sponsored discussions aimed at establishing such definitions (i-3). For terms drawn from the area of colloid and interface science, much reliance was placed on the recommendations of the lUPAC Commission on Colloid and Surface Chemistry (4), For important emulsion terms that are frequently used in industrial practice, the aim was to be consistent with the standard petroleum dictionaries such as references 5-7. 

The oily 3-methyl-l-phenyl-1,3-butanedione(l g) is added to a solution of sodium (0.15 g) in methanol (3 ml), and the deep yellow solution is at once filtered and dropped into 5n-sulfuric acid (30 ml) cooled in ice-salt. The emulsion that is thus first formed must be whipped vigorously with a glass rod to cause solidification, so that most of the material becomes finely powdered and readily filterable if the oil globules once become large the product does not crystallize well and is unstable. The solid precipitate is at once filtered off, washed with very dilute hydrochloric acid, followed by ice-cold ethanol and then light petroleum, and is finally recrystallized from low-boiling light petroleum in a quartz vessel. The m.p. is 51° and the yield almost quantitative. 

LLE is a widely used technique for extracting pesticides from water samples. The selectivity of LLE is dependent on the particular solvent used and the nature of the water matrix. Other variables such as pH, ionic strength, watensolvent ratio, number of extractions, and type and concentration of analyte, must also be considered [28]. The most common extraction solvents used for this purpose include dichloromethane [31-35], -hexane [32,35], light petroleum [32], and ethyl acetate [36,37]. This technique has a number of drawbacks including the formation of emulsions, the need to use toxic or flammable solvents, and its labor-intensive and time-consimiing nature. Continuous systems based on custom-made phase separator furnished with a fluorophore [37] or polypropylene membrane have helped expedite the LLE of pesticides from water [38,39]. 

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