Surfactants manufacture

E. A. Knaggs, "The Role of the Independent Surfactant Manufacturer iu Tertiary Oil Recovery", paper presented at MCS Chemical Marketing and... 

Polyall lene Oxide Block Copolymers. The higher alkylene oxides derived from propjiene, butylene, styrene (qv), and cyclohexene react with active oxygens in a manner analogous to the reaction of ethylene oxide. Because the hydrophilic oxygen constitutes a smaller proportion of these molecules, the net effect is that the oxides, unlike ethylene oxide, are hydrophobic. The higher oxides are not used commercially as surfactant raw materials except for minor quantities that are employed as chain terminators in polyoxyethylene surfactants to lower the foaming tendency. The hydrophobic nature of propylene oxide units, —CH(CH2)CH20—, has been utilized in several ways in the manufacture of surfactants. Manufacture, properties, and uses of poly(oxyethylene- (9-oxypropylene) have been reviewed (98). 

A surfactant was defined in Chapter 8 as an agent, soluble or dispersible in a liquid, which reduces the surface tension of the liquid [1]. It is helpful to visualise surfactant molecules as being composed of opposing solubility tendencies. Thus, those effective in aqueous media typically contain an oil-soluble hydrocarbon-based chain (the hydrophobe) and a smaller water-solubilising moiety which may or may not confer ionic character (the hydrophile). The limitations of space do not permit a comprehensive detailed treatment of the chemistry of surfactants. The emphasis is therefore on a broad-brush discussion of the principal types of surfactant encountered in textile preparation and coloration processes. Comprehensive accounts of the chemistry and properties of surfactants are available [2-13]. A useful and lucid account of the chemistry and technology of surfactant manufacturing processes is given by Davidsohn and Milwidsky [ 14] ... 

E. Matthijs, P. Gerike, H. Klotz, J.G.A. Kooijman, H.G. Karber and J. Waters, Removal and Mass Balance of the Cationic Fabric Softener Di(Hydrogenated)Tallow Dimethyl Ammonium Chloride in Activated Sludge Sewage Treatment Plants European Association of Surfactant Manufacturers (AIS/CESIO), Brussels, Belgium, 1992. 

A series of publications dedicated to soil-associated LAS has been authored or initiated by the surfactant-manufacturing industry. It was already in 1990 when Mieure et al. [12] presented a safety assessment for LAS for terrestrial plants and animals comparing measured LAS concentrations in soil environments with the lowest effect concentrations for typical organisms.1 In 1998, de Wolf and Feijtel [13]... 

Most commercial products are mixtures because of the way they are manufactured. For instance many surfactant hydrophobes come from assorted products such as petroleiun alkylate cuts or triglyceride oils, with a molecular weight distribution that could be narrow or wide. Usually, a purification and separation of single isomeric species would be too costly and, in most cases, pointless. Moreover, the synthesis reactions involved in the surfactant manufacturing might be the intrinsic reason of the production of a mixture, such as in the case of polycondensation of ethylene oxide which results in an often wide spread ethylene oxide munber (EON) distribution. A residual content of some intermediates or by-products might also be a significant cause for mixture effects. 

SMEs are often based on the methyl ester of coconut oil or palm kernel oil, both of which give a carbon distribution predominantly of Ci2 u. Products based on palm stearine, a lower cost oil with mainly C16 18 carbon chains, are more difficult to process, and additional care is needed to avoid producing a dark coloured surfactant. The sources and processing of oleochemcials used in surfactant manufacture will be discussed in more detail later. 

There are over 150 different producers and some 2 million tonnes of commercial nonionic surfactants manufactured worldwide of which at least 50% are alkoxylated alcohols. Ethoxylated nonylphenol production is falling and accounts for 20% of the market while alkoxylated fatty acids account for some 15%. Fatty acid amides and sugar esters account for another 10% and there are a large number of specialities making up the balance. In general, non-ionic surfactants are easy to make, relatively inexpensive and derived from a variety of feedstocks. 

The total degree of unsaturation of any alkylene functionality is measured by its iodine value [34]. The iodine value measures the equivalents of iodine added across all the unsaturation points in a molecule. Table 6.2 shows the iodine value and 16 and 18 carbon atom percentages of typical feedstocks used in cationic surfactant manufacture [35]. 

The estimated cost of testing as shown below will put a disproportionate burden on the small and medium enterprise surfactant manufacturers where the tonnages may be in the 100-1000 tonne band but where the selling price for some of the products is in the 600- 800 per tonne range and the profit margins on these products as low as 80-120 per tonne. 

One of the major non-food uses of vegetable oils (approximately 5(X) million pounds of oil per annum in the US) is the production of soaps, detergents, and other surfactants. The solubility and other physical properties of medium-chain fatty acids and their derivatives make them especially suited for surfactant manufacture. Coconut and palm kernel oils, which contain 40-60% lauric acid (12 0), are current major feedstocks for the surfactant industry. The mechanism of synthesis of lauric and other medium-chain fatty acids in plants involves the action of a medium-chain acyl-ACP thioesterase which terminates fatty acid synthesis after a 10 or 12 carbon chain has been assembled (M. Pollard,... 

The following rather symbolic but at the same time graphic comparison gives one a feeling for the role that the surfactants manufactured worldwide annually can play when they are distributed within the adsorption layers if distributed evenly, 6 million tons of surfactants with Mr 200 g mol"1 can cover the surface of our planet in 10-15 monolayers... 

Fatty alcohols make up one of the major basic oleochemicals having an increasing growth rate. As a primary raw material for surfactants, growth in fatty alcohol production parallels increasing economic prosperity and improved standards of living. Fatty alcohols are the raw materials of choice for surfactant manufacture because of their biodegradability and availability from renewable resources. 

Polysorbates are also commonly used as (O/W) emulsifiers in the food industry (salad dressing, ice cream), and in cosmetics, pharmaceuticals, detergents, and in a myriad of other industrial applications. Current Western Europe consumption of sorbitol for surfactants manufacture can be estimated at around 15,000 tons per year. 

In surfactant manufacture, propylene oxide (PO) is employed both as a hydrophobe (see Section 2.3 above), and as a modifier for poly(ethylene oxide). Propylene oxide is similar to EO except that it contains an additional methyl group, which adds steric bulk, and is significantly more hydrophobic in nature. If PO is inserted in the middle of an poly(ethylene oxide) chain, different properties (e.g. greater liquidity) are obtained. Since this approach requires three separate alkoxylations, it is only used when modification of specific properties is required. More common is the use of PO to cap the end of the poly(ethylene oxide) chain. This significantly reduces foaming, which can be critical in certain applications (e.g. machine dishwashing). 

Surfactant manufacturers produce a limited number of emulsifiers with HLB values along the continuum between 11 and 14. The most popular of these are nonylphenol ethoxylates with 9 to 10 moles of ethylene oxide (E.O. = 9 to 10 HLB 12.9 to 13.5) such as Triton N-101, Surfonic N-95, Surfonic N-lOO, Igepal2 CO-630, Sterox NJ, Polytergent b-350, T-DET-N 9.5, and Alkasurf NPX. Figure 5 shows a phase diagram of a cocktail using such an emulsifier system. 

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