Soaps fatty acid neutralization

Fatty Acid Neutralization. Another approach to produce soap is through the neutralization of fatty acids with caustic. This approach requires a stepwise process where fatty acids are produced through the hydrolysis of fats and oils by water, followed by subsequent neutralization with appropriate caustics. This approach has a number of inherent benefits over the saponification process. 

Zn-EMAA ionomers, 74 464-465, 474, 482. See also EMAA ionomers Zn-EPDM elastomeric ionomers, 74 482 ZnSe system, for laser diodes, 22 179 Zn-soap, in fatty acid neutralization, 22 740... 

Figure 4 Soap from fatty acid neutralization (C) (from Ref. 13).

Parameter Batch kettle (A) Fat splitting (B) Fatty acid neutralization Glycerine (C) concentration (D) Glycerine Flakes and distillation (E) powders (F) Bar soap (G) Liquid soap (H)... 

Fig. 36.2). The methyl ester process for soap manufacture is typically more capital and cost intensive versus the more traditional fats/oils saponification and fatty acid neutralization processes. 

The following describes neutral fat saponification and fatty acid neutralization, the two principal processes used for manufacture of soap in the world markets today. 

Fatty Acid Neutralization. The acid-base reaction of fatty acids with alkali to produce soap (below) is much faster than the corresponding reaction of triglycerides with alkalis. 

A typical Mazzoni fatty acid neutralization soap plant is illustrated in Fig. 36.5.6 The operation of this plant involves the pumping of the reactants through preheaters to a turbodisperser, or high-shear mixer, where the contact of the reactants with each other initiates the formation of neat soap. The soap mass, which is partially reacted at this stage, then proceeds to the mixer where it is recirculated until the neutralization is complete. The completion of the neutralization reaction is monitored continuously by an electric potential (millivolt, mV) measurement for alkalinity. The neat soap is then dried by vacuum spray-dryers, as described earlier, to produce soap pellets ready for finishing into soap bars. 

Numerous catalysts have been used in the production of CLA. We have found that hydroxides of lithium, sodium, and potassium are all capable of generating CLA in various solvents. As fatty acids neutralize the catalyst, it is necessary to add at least one mole of catalyst for every mole of fatty acid in the reaction to ensure soap is generated. We have found that, on a molar basis, potassium hydroxide has proven to be a more effective catalyst than sodium hydroxide, with lithium hydroxide the least effective and not suited for industrial CLA production. On a weight basis, sodium and potassium hydroxide have similar efficiency of conversion. Although sodium hydroxide is much less expensive than potassium hydroxide, the disposal costs for the waste neutralized alkali should also be considered. Potassium salts are easily used as fertilizer and can be applied to fields, whereas sodium salts cannot be disposed of in a similar fashion. 

When soap is produced from most triglyceride saponification or fatty acid neutralization soap-... 

Current mass market soap manufacturing is based primarily around continuous soap making using either fat saponification or by fatty acid neutralization, utilizing a wide variety of natural and synthetic feedstocks. The soap chips produced are then usually finished using a high-speed soap line comprised of refiner mill, extruder, and stamper. Batch... 

Reaction with Fatty Acids and Esters. Alkanolamines and long-chain fatty acids react at room temperature to give neutral alkanolamine soaps, which are waxy, noncrystaUine materials with widespread commercial appHcations as emulsifiers. At elevated temperatures, 140 —160°C, A/-aIkanolamides are the main products, at a 1 1 reaction ratio (7,8). 

Saponification can proceed direcdy as a one-step reaction as shown above, or it can be achieved indirectly by a two-step reaction where the intermediate step generates fatty acids through simple hydrolysis of the fats and oils and the finishing step forms soap through the neutralization of the fatty acid with caustic soda. There are practical considerations which must be addressed when performing this reaction on a commercial scale. 

Commercially, soap is most commonly produced through either the direct saponification of fats and oils with caustic or the hydrolysis of fats and oils to fatty acids followed by stoichiometric (equal molar) neutralization with caustic. Both of these approaches yield workable soap in the form of concentrated soap solutions (- 70% soap). This concentration of soap is the target on account of the aqueous-phase properties of soap as well as practical limitations resulting from these properties. Hence, before discussing the commercial manufacturing of soap, it is imperative to understand the phase properties of soap. 

The refining process most commonly used involves treatment with hot aqueous alkaH to convert free fatty acids to soaps, followed by bleaching, usually with hydrogen peroxide, although sodium chlorite, sodium hypochlorite, and ozone have also been used. Other techniques include distillation, steam stripping, neutralization by alkaH, Hquid thermal diffusion, and the use of active adsorbents, eg, charcoal and bentonite, and solvent fractionation... 

---