To remove color bodies

A final example of application and process layout is shown in Figure 15. In this example the process relies on activated carbon to remove color bodies from a recycled glucose intermediary prior to use in the production of confectionary. The glucose containing the color taint must be mildly heated (to about 70° C), so that the normally solid product becomes less viscous and easier to pump. The syrup is... 

Clay filter the fuel to remove color bodies. 

Contact filtration a process in which finely divided adsorbent clay is used to remove color bodies from petroleum products. 

The bleaching of rendered fats, typically using commercially available bleaching clays, is done to remove color bodies and other contaminants that darken the color of the fat. Raw rendered fats are usually described by FAC (the Fat Analysis Committee of the American Oil Chemists Society) colors as outlined by the American Oil Chemists Society (AOCS) Method Ccl3a-43. The AOCS notes that the 1992 version was declared obsolete and was removed from the book of methods in 1993. However, its use is not precluded and its official method status is not changed. 

The bleaching process is used to remove color bodies and other minor impurities. The bleaching adsorbent, usually a clay product, removes residual soap from alkali refining, aldehydes and ketones from decomposed peroxides, and color bodies. The color of bleached oil is widely measured by the Lovibond tintometer color scale. 

Typical processes for air/S03 sulfonation of alpha olefins are shown in Fig. 26.18 (alpha olefins), and for air/SO3 sulfation of fatty acohols in Fig. 26.19. Bleaching often is required in the post-hydrolysis steps to remove color bodies prior to neutralization. 

The cmde phthaUc anhydride is subjected to a thermal pretreatment or heat soak at atmospheric pressure to complete dehydration of traces of phthahc acid and to convert color bodies to higher boiling compounds that can be removed by distillation. The addition of chemicals during the heat soak promotes condensation reactions and shortens the time required for them. Use of potassium hydroxide and sodium nitrate, carbonate, bicarbonate, sulfate, or borate has been patented (30). Purification is by continuous vacuum distillation, as shown by two columns in Figure 1. The most troublesome impurity is phthahde (l(3)-isobenzofuranone), which is stmcturaHy similar to phthahc anhydride. Reactor and recovery conditions must be carefully chosen to minimize phthahde contamination (31). Phthahde [87-41-2] is also reduced by adding potassium hydroxide during the heat soak (30). 

Tall oil rosin is a by-product of paper manufacturing. Raw wood chips are digested under heat and pressure with a mixture of sodium hydroxide and sodium sulfide. Soluble sodium salts of lignin, rosin, and fatty acids are formed, which are removed from the wood pulp as a dark solution. The soaps of the rosin and fatty acids float to the top of the mixture, where they are skimmed off and treated with sulfuric acid to free the rosin and fatty acids. This mixture, known as cmde tall oil (CTO), is refined further to remove color and odor bodies fractional distillation separates the tall oil rosin acids from the fatty acids (see Tall oil). 

Rx mixture separates, H2O often added to facihtate color bodies partially removed into separated spent H2SO4... 

In addition to removing colored impurities and other colloids, ion exchange resins effectively remove the uncolored precursor of these colored substances. It has long been recognized that a small amount of 5-hydroxymethylfurfural (HMF), formed from dextrose by the action of acid catalysts, decomposes to form organic acids as well as pigments which polymerize to form highly colored bodies.23 Normal bone char... 

Hydrotreat to reduce olefins and remove color bodies. 

Refinery Bleach. Various bleaching clays purify and remove color bodies from refined oils. These wastes contain 5% to 35% oil. The characteristics of these materials are such that they will combust spontaneously, which has created problems for disposal in sanitary landfills, as well as at factory locations in some instances, but this condition can be overcome by several methods. The model refinery presented in the previous section will generate about 2500 kg of waste earth per day, of which 570 kg is oil. 

Raw lac is first treated to remove water-soluble carbohydrates and the dye that gives lac its red color. Also removed are woody materials, insect bodies, and trash. It is further refined by either hot filtration or a solvent process. In the heat process, the dried, refined lac is filtered molten through cloth or wine screens to produce the standard grades of orange shellac. In the solvent process, lac is dissolved and refluxed in alcohol solvents, filtered to remove dirt and impurities, and concentrated by evaporation. The lac can be further decolori2ed in this process to produce very pale grades. Bleached shellac is prepared by treatment with dilute sodium hypochlorite and coalesced into slabs. 

Sodium and Potassium Benzoate. These salts are available in grades meeting the specifications of the 25ationalVormulary (18) and the Vood Chemicals Codex (19) (Table 7). Sodium benzoate [532-32-1] is produced by the neutralization of benzoic acid with caustic soda and/or soda ash. The resulting solution is then treated to remove trace impurities as weU as color bodies and then dried in steam heated double dmm dryers. The product removed from the dryers is light and fluffy and in order to reduce shipping and storage space the sodium benzoate is normally compacted. It is then milled and classified into various product forms, the names of which often bear Httle relationship to the actual form of the product. 

Distillation. Most fatty acids are distilled to produce high quaHty products having exceUent color and a low level of impurities. Distillation removes odor bodies and low boiling unsaponifiable material in a light ends or heads fraction, and higher boiling material such as polymerized material, triglycerides, color bodies, and heavy decomposition products are removed as a bottoms or pitch fraction. The middle fractions sometimes can be used as is, or they can be fractionated (separated) into relatively pure materials such as lauric, myristic, palmitic, and stearic acids. 

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