Odor and Color

In studying the environmental effects of naphtha, it is necessary to relate volatility to the fire hazard associated with its use, storage, and transport, and also with the handling of the products arising from the process. This is normally based on the characterization of the solvent by flash point limits (ASTM D56, D93 IP 34, 170) 

The significance of the measured properties of residual fuel oil is dependent to a large extent on the ultimate uses of the fuel oil. Such uses include steam generation for various processes, as well as electrical power generation and propulsion. Corrosion, ash deposition, atmospheric pollution, and product contamination are side effects of the use of residual fuel oil, and in particular cases, properties such as vanadium, sodium, and sulfur contents may be significant. 

The character of fuel oil generally renders the usual test methods for total petroleum hydrocarbons (Chapters 7 and 8) ineffective since high proportions of the fuel oil (specifically, residual fuel oil) are insoluble in the usual solvents employed for the test. In particular, the asphaltene constituents are insoluble in hydrocarbon solvents and are only soluble in aromatic solvents and chlorinated hydrocarbons (chloroform, methylene dichloride, and the like). Residua and asphalt (Chapter 10) have high proportions of asphaltene constituents, which render any test for total petroleum hydrocarbons meaningless unless a suitable solvent is employed in the test method. 

Testing residual fuel oil does not suffer from the issues that are associated with sample volatility but the test methods are often sensitive to the presence of gas bubbles in the fuel oil. An air release test is available for application to lubricating oil (ASTM D3427 IP 313) and may be applied, with modification, to residual fuel oil. However, with dark-colored samples, it may be difficult to determine 

The degree of purity of naphtha is an important aspect of naphtha properties, and strict segregation of all distribution equipment is maintained to ensure strict and uniform specification for the product handled. Naphtha is refined to a low level of odor to meet the specifications for use. 

In general the paraffinic hydrocarbons possess the mildest odor and the aromatics the strongest, the odor level (ASTM D-268, ASTM D-1296, IP 89) being related to the chemical character and volatility of the constituents. Odors caused by the presence of sulfur compounds or unsaturated constituents are excluded by specification. And apart from certain high-boiling aromatic fractions, which are usually excluded by volatility from the major- 

Measurement of color (ASTM D-156, ASTM D-848, ASTM D-1209, ASTM D-1555, ASTM D-5386, IP 17) provides a rapid method of checking the degree of freedom from contamination. Observation of the test for residue on evaporation (ASTM D-381, ASTM D-1353, IP 131) provides a further guard against adventitious contamination. 

Distillation, as a means of determining the boiling range (hence the volatility) of petroleum and petroleum products, has been in use since the beginning of the petroleum industry and is an important aspect of product specifications. 

Thus one of the most important physical parameters is the boiling range distribution (ASTM D-86, ASTM D-1078, ASTM D-2887, ASTM D-2892, IP 123). The significance of the distillation test is the indication of volatility, which dictates the evaporation rate, an important property for naphtha used in coatings and similar applications where the premise is that the naphtha evaporates over time, leaving the coating applied to the surface. 

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The quaHty, ie, level of impurities, of the fats and oils used in the manufacture of soap is important in the production of commercial products. Fats and oils are isolated from various animal and vegetable sources and contain different intrinsic impurities. These impurities may include hydrolysis products of the triglyceride, eg, fatty acid and mono/diglycerides proteinaceous materials and particulate dirt, eg, bone meal and various vitamins, pigments, phosphatides, and sterols, ie, cholesterol and tocopherol as weU as less descript odor and color bodies. These impurities affect the physical properties such as odor and color of the fats and oils and can cause additional degradation of the fats and oils upon storage. For commercial soaps, it is desirable to keep these impurities at the absolute minimum for both storage stabiHty and finished product quaHty considerations. 

The fatty acids obtained from the process can be used directly or further manipulated for improved or modified performance and stabiUty. Hardening is an operation in which some fraction of the unsaturated bonds present in the fatty acids are eliminated through hydrogenation or the addition of H2 across a carbon—carbon double bond. This process was initially intended to improve the odor and color stabiUty of fatty acids through elimination of the polyunsaturated species. However, with the growth in the use of specialty fatty acids, hydrogenation is a commercially important process to modify the physical properties of the fatty acids. 

The physical properties of the fatty acid ethoxylates depend on the nature of the fatty acid and even more on ethylene oxide content. As the latter increases, consistencies of the products change from free-flowing Hquids to slurries to firm waxes (qv). At the same time, odor, which is characteristic of the fatty acid, decreases in intensity. Odor and color stabiUty are important commercial properties, particularly in textile appHcations. Oleic acid esters, though possessing good functional properties, cannot be used because they tend to yellow on exposure to heat and air. 

Many attempts have been made to reduce the ammoniacal and sulfurous odor of the standard thioglycolate formulations. As the cosmetics market is very sensitive to the presence of impurities, odor, and color, various treatments of purification have been claimed to improve the olfactory properties of thioglycolic acid and its salts, such as distillation (33), stabilization against the formation of H2S using active ingredients (34), extraction with solvents (35), active carbon (36), and chelate resin treatments (37). 

Benzoic acid Pharmaceutical grade, odor- and color free 4,500 99.97% Falling film Italy Chimica del Friuli... 

Odor and color instability was traced to the choice of SAI. The original Monsavon composition used an SAI blend made from 80% coconut fatty acid and 20% tallow fatty acid. A characteristic alkyl chain length distribution for the resulting SAI is shown in Table 9.4-1. 

Odor and color stability problems were also related to the alkyl chains used for SAI. These could be traced to the oxidation of unsaturated carbons, such as oleic acid (Ci8 fatty acid with a single double bond between carbon 9 and 10, i.e. bond position 9 counted from the carboxyl carbon), linoleic acid (Cis fatty acid with two double bonds at position 9 and 12), and linolenic acid (Cis fatty acid with three double bonds at position 9, 12, and 15). Natural coconut fatty acid contains about 6% oleic acid, about 3% linoleic acid, and less than 1% linolenic acid. Tallow fatty acid contains nearly 44% oleic and about 6% of other unsaturates [20]. Partial hydrogenation of the coconut fatty acid used in the manufacture of SCI served to eliminate linoleic and linolenic acids for improved odor stability, while not eliminating oleic acid, which is important for good lather. 

Ozone has many industrial applications. It is a sterilizing and deodorizing agent. It is used for disinfection of filtered drinking water and to purify waste-waters. It also is used in water treatment plants for removal of metal impurities by oxidizing them into insoluble compounds. This removes undesired taste, odor, and color from the water. Ozone also is used for odor control. 

The use of cracked stocks in No. 2 has meant additional problems for the refiner. Besides having to refine for odor and color, he is also faced with a stability problem. While catalytic cracking as a rule produces a more stable oil than does thermal cracking, there are still compounds present which on aging will form insoluble sludge. This sludge, if permitted to form, clogs burner screens, and eventually results in trouble. 

The two prime objectives of this process, maintenance of good odor and color in the distillate and proper bottoms yield, are achieved by effective control over vacuum, temperature, and distillation rate. 

Sweetening the process by which petroleum products are improved in odor and color by oxidizing or removing the sulfur-containing and unsaturated compounds. 

Although the perfume oil is usually the first suspect whenever odor or color changes occur in a finished product, it is not always the culprit. Odor and color changes in the product base itself may occur due to oxidation, hydrolytic breakdown, complex formation, bacterial decomposition, or other causes. Sometimes the causes for instability are hard to track down, as in a case in the experience of one of the authors, where an off-odor in a cream was due to microbial breakdown that was made possible by absorption and inactivation of the preservative by the plastic container. It is always advisable to conduct a stability test of the unperfumed product along with the test of the perfumed product. 

Chlorine from Hydrochloric Acid. Place about 0.5 gram each of manganese dioxide, lead dioxide, sodium dichromate, and potassium permanganate in separate test tubes. Add about 2 cc. of 6 N hydrochloric acid to each and test for chlorine by holding iodide-starch paper in the mouths of the tubes. Also after warming a very little observe the odor and color of the gas. Rinse out the tubes immediately at the sink under the hood. Compare the action of the oxides used above with that of copper oxide CuO and lead oxide PbO. 

The removal of contaminants (unreacted triglycerides, odor and color bodies, polymerized matter, and decomposition products) from split fatty acids is achieved by simple distillation.17a,b The products obtained from such straight distillations are called whole cut fatty acids (e.g., whole coconut fatty acid). 

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