Byproduct quality

The raw materials for the manufacture of soap, the alkali salts of saturated and unsaturated C10-C20 carboxylic acids, are natural fats and fatty oils, especially tallow oil and other animal fats (lard), coconut oil, palm kernel oil, peanut oil, and even olive oil. In addition, the tall oil fatty acids, which are obtained in the kraft pulping process, are used for soap production. A typical formulation of fats for the manufacture of soap contains 80-90% tallow oil and 10-20% coconut oil [2]. For the manufacture of soft soaps, the potassium salts of fatty acids are used, as are linseed oil, soybean oil, and cottonseed oil acids. High-quality soap can only be produced by high-quality fats, independent of the soap being produced by saponification of the natural fat with caustic soda solution or by neutralization of distilled fatty acids, obtained by hydrolysis of fats, with soda or caustic soda solutions. Fatty acids produced by paraffin wax oxidation are of inferior quality due to a high content of unwanted byproducts. Therefore in industrially developed countries these fatty acids are not used for the manufacture of soap. This now seems to be true as well for the developing countries. 

The paraffin wax is oxidized by air in a liquid phase process at 110-130°C. Catalysts for this radical reaction are cobalt or manganese salts [54]. The quality of the obtained mixture of homologous carboxylic acids is impaired by numerous byproducts such as aldehydes, ketones, lactones, esters, dicarboxylic acids, and other compounds. These are formed despite a partial conversion of the paraffin and necessitate an expensive workup of the reaction product [50,55]. 

In spite of all their merits, ester sulfonates have not been used to a great extent as yet [12]. The reason is that a practicable process for producing a-sulfo fatty acid esters with good qualities is difficult because of the formation of byproducts with worse properties (e.g., the disalts of the a-sulfo fatty acids). 

Dioxane forms by the chemical cleavage of two molecules of ethylene oxide from the parent ethoxylated alcohol. Dioxane is the undesirable byproduct. The amount of dioxane ranges from traces to hundreds, even thousands, of ppm (mg/kg) depending on raw material quality and sulfonation/neutralization process conditions. 

During the sulfation of alcohol ethoxylates the undesired byproduct 1,4-di-oxane may be formed. Although the formation of 1,4-dioxane is predominantly governed by the sulfation and neutralization conditions and by the chemical composition of the organic feedstock, other factors, such as the quality of the raw material, also contribute. This prompted a reappraisal of the required quality standards for this feedstock. In Table 11 guideline specifications are presented. 

For the organic contaminants, the required bromine product quality wilt also be site specific. If the catalytic oxidation unit is dedicated to a single bromination process, phase separation and drying may be the only purification required. Contaminants in the recovered bromine which are either the starting materials or products of the original bromination reaction should not present a problem if present in bromine recycled to the bromination reactor. In this case, the catalytic reactor would be operated to minimize the formation of undesirable brominated byproducts. For example, if phenol is present in the waste HBr from a tribromo-phenol manufacturing process, minor tribromophenol contamination of the bromine recycled to the reactor should not be a problem. Similarly, fluorobenzene in bromine recycled to a fluorobenzene bromination process should not present a problem. 

Selective hydrogerration over low-loading, supported Cu catalysts has shown to be a valuable tool for the production of high quality biodiesel from Tall Oil, a byproduct of the Pulp Paper indrrstry. These resrrlts allow planning the use of a great variety of non-conventiorral oils with high iodine value for the production of biodiesel. 

Less hydrogen consumption may be required for the production of high quality products because less gaseous hydrocarbon byproducts are produced. 

These first examples illustrate the importance of a sufficient separation of products and byproducts, whereas membranes are one possibility in pharmaceutical production to obtain this aim. Therefore, they are one key tool to obtaining better quality products and environmentally friendly processes. For a more detailed article about the state of the art of membranes in biotechnology, see Rios et al. [27]. At the same time, it can be seen that stoichiometric cofactor need is no longer a limitation for industrial biotransformations, since they can be overcome with efficient recyclization methods. 

In most applications, the first reaction in each set is an acid-base reaction so that k is very large. For Eq. (59), B and C are premixed and added to A under conditions such that B is in stoichiometric excess to A. Likewise, for Eq. (58), B is reacted in stoichiometric excess with A to produce the desired product R. Under these conditions, the first reaction in each set is favored. However, if mixing occurs with the same time scale as the second reaction, the undesired byproduct (S in Eq. (58) and P2 in Eq. (59)) will be produced. Thus, the amount of by-product produced is a sensitive measure of the quality of mixing in the chemical reactor. 

For products requiring high-quality sulfates, chlorosulfonic acid is an excellent corrosive agent that generates hydrochloric acid as a byproduct. A process flow diagram is shown in Figure 13. The effluent washouts are minimal. 

Phosphorus is manufactured by the reduction of commercial-quality phosphate rock by coke in an electric furnace, with silica used as a flux. Slag, ferrophosphorus (from iron contained in the phosphate rock), and carbon monoxide are reaction byproducts. The standard process, as shown in Figure 2, consists of three basic parts phosphate rock preparation, smelting in an electric furnace, and recovery of the resulting phosphoms. Phosphate rock ores are first blended so that the furnace feed is of uniform composition and then pretreated by heat drying, sizing or agglomerating the particles, and heat treatment. 

Hower, J. C Robl, T. L. Thomas, G. A. 1999a. Changes in the quality of coal combustion byproducts produced by Kentucky power plants, 1978 to 1997 consequences of Clean Air Act directives. Fuel, 78, 701-712. 

---