Alcohol ethoxylate, separation

After the SO converter has stabilized, the 6—7% SO gas stream can be further diluted with dry air, I, to provide the SO reaction gas at a prescribed concentration, ca 4 vol % for LAB sulfonation and ca 2.5% for alcohol ethoxylate sulfation. The molten sulfur is accurately measured and controlled by mass flow meters. The organic feedstock is also accurately controlled by mass flow meters and a variable speed-driven gear pump. The high velocity SO reaction gas and organic feedstock are introduced into the top of the sulfonation reactor,, in cocurrent downward flow where the reaction product and gas are separated in a cyclone separator, K, then pumped to a cooler, L, and circulated back into a quench cooling reservoir at the base of the reactor, unique to Chemithon concentric reactor systems. The gas stream from the cyclone separator, M, is sent to an electrostatic precipitator (ESP), N, which removes entrained acidic organics, and then sent to the packed tower, H, where SO2 and any SO traces are adsorbed in a dilute NaOH solution and finally vented, O. Even a 99% conversion of SO2 to SO contributes ca 500 ppm SO2 to the effluent gas. 

Trathnigg, B., Kollroser, M., Rappel, C. (2001). Liquid exclusion adsorption chromatography, a new technique for isocratic separation of nonionic surfactants. III. Two-dimensional separation of fatty alcohol ethoxylates. J. Chromatogr. A 922(1-2), 193-205. 

The combination of normal (silica) and reversed (C18) phase HPLC in a comprehensive 2D LC system was used for the first time for the analysis of alcohol ethoxylates [64] the NP separation was run using aqueous solvents, so the mobile phases used in the two dimensions were miscible, resulting in the easy injection of the entire first-dimension effluent onto the second-dimension column. 

The second repulsive energy (referred to as steric repulsion) is produced by the presence of adsorbed surfactant layers of nonionic surfactants, such as alcohol ethoxylates or A-B, A-B-A block, or BA graft copolymers, where B is the anchor chain and A is the stabilizing chain [mostly based on polyethylene oxide (PEO) for aqueous systems]. When two droplets or particles with adsorbed PEO chains of thickness 5 approach a separation distance h such that h < 28, repulsion occurs as a result of two main effects. The first arises as a result of the unfavorable mixing of the PEO chains, when these are in good solvent conditions. This is referred to as Gm x and is given by the following expression ... 

A much more demanding task is the analysis of fractions from liquid chromatography, not only with respect to molar mass but also with respect to chemical structure. The separation of a technical fatty alcohol ethoxylate (FAE) by liquid chromatography under conditions where the chain length as well as the end groups direct the separation is presented in Fig. 36. Using this chromatographic technique, the FAE was separated into three main fractions, the first fraction ap-... 

Foam exhibits higher apparent viscosity and lower mobility within permeable media than do its separate constituents.(1-3) This lower mobility can be attained by the presence of less than 0.1% surfactant in the aqueous fluid being injected.(4) The foaming properties of surfactants and other properties relevant to surfactant performance in enhanced oil recovery (EOR) processes are dependent upon surfactant chemical structure. Alcohol ethoxylates and alcohol ethoxylate derivatives were chosen to study techniques of relating surfactant performance parameters to chemical structure. These classes of surfactants have been evaluated as mobility control agents in laboratory studies (see references 5 and 6 and references therein). One member of this class of surfactants has been used in three field trials.(7-9) These particular surfactants have well defined structures and chemical structure variables can be assigned numerical values. Commercial products can be manufactured in relatively high purity. 

The cloud point (CP) of alcohol ethoxylates is the temperature at which solutions of these surfactants become cloudy. The turbidity is caused by the separation of the fluid into two phases a low surfactant concentration and a high surfactant... 

Althongh the ethoxylate structure is shown, alcohol alkoxylates can contain nnits of ethylene oxide, propylene oxide, butylene oxide or mixtnres. Alkyl phenol ethoxylates technically are alcohol ethoxylates however, they are discnssed separately below. 

Cretier et al. [1009] analyzed aliphatic alcohol ethoxylates (non-ionic surfactants). These were separated according to alkyl chain length C o-C)g, and, when collected and combined, were aniayzed as to their degree of ethoxylation. The... 

Another promising method is 2D-LC, a combination of adequately selected two different LC separation conditions. If the separation condition of one dimension separates one block in the IC mode while the other block does not show a strong interaction with the stationary phase, preferably weak enough to elute in the SEC mode (like simultaneous SEC/IC separation condition for mixtures), the interacting block can be separated by IC mode nearly independent of the non-interacting block length and vice versa. Employing the 2D-LC method, Murphy et al. and Jan-dera et al. separated individual blocks of alcohol ethoxylate and PEO-fc-PPO, respectively (Fig. 20) [137-139]. Due to the amphiphilic nature of the block copolymer, the combination of NPLC and RPLC worked well. 

The exhausted gas and organic acid mixture which leave the bottom of the reactor flow into two high-efficiency liquid-gas separators in series. The exhaust gas then flows to the exhaust gas treatment plant. The organic acid is transferred to the next stage, ageing and stabilisation of alkylbenzene sulphonic acid, or straight to the neutralisation unit for alcohols, alcohol ethoxylates and alpha-olefin feedstocks. 

Nonionics. Alcohol ethoxylates and alkylphenol ethoxylates were separated on a fused silica column (30 m X 0.25 mm (0.25 micron film)) of SE-54 using helium as carrier gas and El or Cl (chemical ionisation) (methane) MS detection. Temperature programming was from 70°C (1 min) to 300°C (10 min hold) at 3°C per minute. Ethoxylates up to 6EO units could be detected [6]. 

Alternatively, ethoxylated alcohols were separated on a 50 cm X 0.125 inch column of 10% SE-30 on Chromosorb W DMCS (80-100 mesh) programmed from 50°C to 300°C at 6°C per min with nitrogen as carrier gas and FID. A detailed study of structure/retention time/response factors has been presented [7]. 

Separation of alkylphenol ethoxylates and alcohol ethoxylates on an aluminium clad fused silica column (10 mx 0.53 mm i.d.) of OV-1 with helium as carrier gas, FID and temperature programming to 325 C is presented in [8]. Separations are compared with those from SFC. 

Nonionics. As alcohol ethoxylates have no strong UV chro-mophore, derivatisation to introduce a chromophore is an attractive option. The reaction to form phenyl isocyanate derivatives, which can then be detected by UV, is described in [27]. A micro-Bondapak CIS column was used for separation according to alkyl chain length and a micro-Bondapak amine column for separation according to degree of ethoxylation. 

Figure 9.4 Separation of alcohol ethoxylate by ethoxamer (column 250 x 4.6 mm i.d. of 5 micron Nucleosil Si-50, gradient 99 1 ethyl acetate water to 90 10 acetonitrile water, evaporative light scattering detector).

Alkylphenol ethoxylates can be readily detected by UV. Columns and separation conditions are similar to those for alcohol ethoxylates. Ethoxamer distribution can be determined on a LiChrosorb amine column (250x4.6 mm i.d.) with a hexane/iso-propanol to aqueous iso-propanol gradient system and UV detection at 277 nm [29]. 

Fig. 9. Chromatograms from conventional (single dimensional) separations for the alcohol ethoxylate ...

Trathnigg B. Liquid exclusion—adsorption chromatography new technique for iso-cratic separation of nonionic surfactants, 11. Quantitation in the analysis of fatty alcohol ethoxylates. J Chromatogr A 2001 915 155. 

Figure 7.1.4 Analysis of shower gel containing C12-C14 ethoxylated alcohols by CE (A), HPLC-UV (B). (numbers above peaks indicate the degree of ethoxylation). Separation of fatty alcohol ethoxylates and of Cg-Cio polyglucosides by HPLC-ELSD (C). Adapted from Heinig et al (1998) with permission.

The method below is based on hydrolysis of sulfate groups, followed by column chromatographic separation of derivatives of the resulting alcohols and alcohol ethoxylates. Only the unethoxylated material elutes from a silica gel column. 

Sulfated C12-C15 alcohol 3-mole ethoxylate homolog distribution separation by both alkyl and ethoxy chain length Sulfated C12-C15 alcohol 3-mole ethoxylate determination of alkyl chain length distribution Sulfated C12-C14 alcohol ethoxylate determination of alkyl chain length distribution Sulfated C10-C14 alcohol ethoxylate determination of alkyl chain length distribution separation of isomers... 

Phosphated C 2-C j alcohol ethoxylate determination of alkyl chain length distribution separation of isomers... 

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