Color reduction

Another aspect of process improvement is color improvement. Eor example, use of phosphoric acid and formaldehyde on the dimer product is said to improve color (68). Other treatments, both on the raw materials and on the finished product, have also been used. Most of these are variations of standard fatty material color reduction techniques. 

Although it has been reported (138) that decolorization of wastewater containing reactive azo dyes with sodium hydrosulfite is possible only to a limited extent, others have demonstrated good reduction (decolorization). For example, using zinc hydrosulfite for the decolorization of dyed paper stock (139) resulted in color reduction of 98% for azo direct dyes (139). A Japanese patent (140) describes reducing an azo reactive dye such as Reactive Yellow 3 with sodium hydrosulfite into its respective aromatic amines which ate more readily adsorbable on carbon than the dye itself. This report has been confirmed with azo acid, direct, and reactive dyes (22). 

Reactive groups have minimal auxochrome effect on color intensity, and color yield per molecular weight decreases with increasing numbers of reactive groups. Increased dye fixation and reduced environmental impact of hydrolyzed dye more than compensate for color reduction of additional reactive groups. 

Sufficient color reduction is often achieved by recovery and purification methods. However, sometimes specific color removal is achieved by adsorption to, eg, activated carbon. 

The BR-test constitutes a nonspecific screening assay for the systematic control of raw milk, which combines principles of both agar diffusion and color reduction procedures (36). In this test, the sample is introduced into a microtiter... 

In the makingof this, by the procedures that have been followed in Canada, there are two chemical intermediates which might, some day, be looked at as potential psychedelics under their own colors. Reduction of the compound that is called DON in this Book II (2,5-dimethoxy-4-nitroamphetamine hydrochloride) with Pd/charcoal and hydrogen, gives the 4-amino derivative. This is 2,5-dimethoxy-4-aminoamphetamine dihydrochloride, DOA, which melts at 248-250... 

Bleaching originally was a process for reducing color in oils, but the name has become a misnomer of this industry. Although limited color reduction occurs during the process, the major reduction of red and yellow colors occurs during the high heat of the deodoriza-... 

Whatever the source of the change, color reduction from the characteristic white observed for newly opened cotton is likely to be an indicator of deterioration in quality. Color differences in cotton can be a source of variations in dye shades in finished fabric. Color in raw cotton is measured by the cotton colorimeter. Two characteristics are measured—the reflectance (Rd) and the yellowness (+b)—under standard illumination and density. In the U.S. system, these two values are used to determine the color grade, which was previously determined visually. 

Understanding the effect of moismre on bleaching is somewhat problematic because both bleaching clays and incoming oils can have different levels to begin with. Zschau has reported (113) that the addition of some level of moisture can have a benehcial effect in bleaching of canola oil. His work (Table 11) shows Lovibond red and yellow, and chlorophyll levels improve with increasing moisture up to 0.6 %. Beyond that level, however, additional moismre is deleterious from the standpoint of color reduction. 

Bleaching and color reduction are important in removing contaminants and also in improving the perception of quality in textile sizing applications. For example, the application of bleached tallow or bleached hydrogenated tallow on textile fabrics is preferred over the use of darker fats. When color requirements become important in the use of rendered fats, processors must pay careful attention to raw material selection. An important analysis of the rendered fat is R B color, or refined and bleached color. 

Ozone is particularly effective in terms of color reduction. The removal of color and UV-absorbance is usually conducted in preozonation steps. The color removal results from the depolymerization and loss of aromaticity of humic substances. ... 

Color reduction occurs with each process in soybean oil neutralization processing degumming, refining, bleaching, and deodorization. In fact, the usual color limits for... 

Edible oils are not bleached chemically because the color reduction occurs because of oxidizing reactions that have an undesirable effect on the flavor and oxidative stability of the oil (Sipos Szuhaj, 1996). The effective agents for edible-oil bleaching are natural clays, activated earths, carbon, and synthetic silicates (see detailed descriptions... 

The oil content of the spent bleaching earth may range from 25—75% of the weight of the earth. Oil retention is affected by the type of filters, the type of refined oil bleached, and the degree of color reduction. It is important to recover as much of this oil as possible, but methods that are too efficient may cause desorption of the impurities adsorbed by the bleaching earth from the refined oil. Because it is possible to remove a substantial portion of the oil from the spent earth, it may become a regulatory requirement in the future. Oil can be recovered by several methods, some performed on the cake while it is still in the filter and others after it has been removed from the filter. Some of the procedures for oil recovery include (Patterson, 1976 Ong, 1983 Hong, 1983 Svensson, 1976) ... 

In the making of this, by the procedures that have been followed in Canada, there are two chemical intermediates which might, some day, be looked at as potential psychedelics under their own colors. Reduction... 

Atsalakis, A., Papamarkos, N. Color reduction and estimation of the number of dominant colors by using a self-growing and self-organized neural gas. Eng. Appl. Artif. Intell. 19(7), 769-786 (2006)... 

Celebi, M., Schaefer, G. Neural gas clustering for color reduction. In Proceedings of the International Conference on Image Processing, Computer Vision, and Pattern Recognition, IPCV, vol. 1, pp. 429-432 (2010)... 

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