Separation adsorption acids

Separation Techniques. Current methods for separating fatty acids are by solvent crystaUi2ation or by the hydrophili2ation process. Other methods that have been used in the past, or perhaps could be used in the future, are panning and pressing, solvent extraction, supercritical fluid extraction, the use of metal salts in assisting in separation, separations using urea complexes, and adsorption/desorption. 

The second part of the book covers zeolite adsorptive separation, adsorption mechanisms, zeolite membranes and mixed matrix membranes in Chapters 5-11. Chapter 5 summarizes the literature and reports adsorptive separation work on specific separation applications organized around the types of molecular species being separated. A series of tables provide groupings for (i) aromatics and derivatives, (ii) non-aromatic hydrocarbons, (iii) carbohydrates and organic acids, (iv) fine chemical and pharmaceuticals, (v) trace impurities removed from bulk materials. Zeolite adsorptive separation mechanisms are theorized in Chapter 6. 

The XAD-4 quaternary resin used in these studies was prepared by the Ames Laboratory in Ames, Iowa. This resin had been used in studies by the Ames group for the adsorption and selective separation of acidic material in waste waters. For this study, the resin was chosen for its effectiveness in concentrating anionic material from solution. At the same time, it was thought that sufficient sites would be available to effectively adsorb neutral organic compounds from water. The resin was basically an XAD-4 macroreticular cross-linked polystyrene into which a trimethylamine group was introduced. The resin was stored in the chloride form but was converted to the hydroxide form before use in the resin sorption experiments. 

Citric acid separation - [ADSORPTION,LIQUID SEPARATION] (Vol 1)... 

The performance of commerically available coated and uncoated capillaries utilizing electroosmotic mobilization has been assessed for model protein mixtures [71]. Although successful separations of basic and neutral proteins were achieved on uncoated capillaries, coated capillaries were required for the separation of acidic proteins in order to provide a constant EOF throughout the capillary. Yeo and Regnier [72] have reported novel coatings for CIEF, which are produced by dynamically modifying octade-cylsilane-derivatized capillaries by adsorption of methylcellulose or surfac-... 

High-performance liquid chromatography (or less common, high-pressure liquid chromatography, HPLC) is a preferred method of analysis for many compounds because it does not require the high temperatures used in gas chromatography. Separations in HPLC can be based on either a size exclusion or on an adsorption principle. The size exclusion mode is useful for separating fatty acids from... 

Tomarelli et al. (T32) separated, after acid hydrolysis and purification by charcoal adsorption and chromatography, a crystalline compound from hog gastric mucin which was highly active in L. bifidus assays. It was reported to be a disaccharide containing acetylglucosamine. 

Several studies of O2 uptake by pre-adsorbed 77-allyl species confirm that a surface complex is initially formed. With a surface 7r-allyl concentration of 50% saturation (to minimize reactions between w-allyls and oxidation intermediates), i.r. spectra of the intermediate were compared with those obtained from separate adsorption of molecules which were likely candidates. Kugler and Kokes concluded from this approach that the intermediate was indeed acrolein, on account of a 1 1 correspondence of the spectra. Other candidates studied were allene, propanal, propan-l-ol, propan-2-ol, acetone, propionic and acetic acids, and acetaldehyde. Only the spectra for acrolein resembled that produced from propene plus O2. 

The separation of acidic or basic products may cause difficulties in adsorption chromatography. Reversed-phase or ion-exchange chromatography would be more suitable but solubility problems may arise. One answer is to use buffered silica, as shown in Figure 9.9. The silica is treated either as bulk material or in the column with a buffer solution of a suitable pH (acidic buffer for acidic samples, basic buffer for... 

By adding sufficient carbon, the color and the HCI can be completely adsorbed. This raises a question as to the manner in which the latter portion of dye is adsorbed Is it adsorbed as RCI, or as ROH with separate adsorption of the HCI Miller studied the adsorption using many different.proportions of dye and carbon. He found that the adsorption of dye color and chloride anion followed dissimilar paths, indicating independent adsorption of dye and acid. Separate adsorption is indicated by the fact that when... 

Table 2 shows the adsorbed concentrations of the pure components. At a partial pressure of 6.6 kPa the amount of n-hexane is just slightly higher than that of isohexane in silicalite-1, while the linear alkane is obviously adsorbed more strongly than 2-methylpentane in H-ZSM-5 due to the stronger interaction with the acid sites. The maximum loading of each component has been measured by a separate adsorption study. The sorption capacity of n-hexane (7 molecules per unit cell), in agreement with earlier studies [48,59-61] exceeds that of 2-methylpentane (4 molecules per unit cell). The latter value equals the number of channel intersections in the MFI pore system per unit cell. Indeed, the sorption of isohexane molecules at... 

Amino acids can also be bound to basic ion-exchange resins charged with hydroxyl ions, but such systems are difficult to operate because of the strongly basic conditions and the problems of C02 adsorption. The acidic amino acids are, however, easily bound to a basic resin in the acetate form, whereas neutral and basic amino acids pass through. The acidic amino acids can subsequently be eluted with aqueous acetic acid. In this way group separation between, acidic and neutral + basic amino acids can be obtained ... 

The separation of acidic or basic products may cause difficulties in adsorption chromatography. Reversed-phase or ion-exchange chromatography would be... 

Fully dehydroxylated covalent surfaces have a homopolar character, with no sensible charge separation. Adsorption on covalent solids is mainly physical covalent surfaces tend to be hydrophobic, and extensive hydroxylation requires high temperatures. Hydroxyl groups present on partially dehydroxylated surfaces show very weak acidic character. They act as hydrogen bond donors with most bases and can protonate only very strong bases. A typical example is silica [35]. 

It should be mentioned that the standard method API RP 42 has drawbacks [9]. For example, it does not take into account loss of surfactant due to adsorption on the rock surface [S, 9]. Once the concentration of the surfactant in the injected acid decreases due to adsorption or phase separation (precipitation), acid-oil sludge will form [32], Rietjens [41] recommended performing acid sludge tests using flow systems (coreflood experiments) to overcome some of the problems encountered with the API RP 42 procedure. 

Talc, a magnesium silicate mineral of composition Mg3[Si40io](OH)2, has a layer lattice. The surface available for adsorption depends markedly on its state of division. Ordinary commercial preparations have been used to separate fatty acids [120] and lanatosides [787]. About 1.5 times its amount of propanol or ethanol is needed to prepare the slurry. 

The technique for the isolation of nicotinic acid depends on the starting material. In most cases, a preliminary hydrolysis is required either with acids or alkalies. The extractions are more complete if the material is rendered free of lipids, a necessary step when working with animal products. The free acid is extracted from the hydrolysate with organic solvents such as hot alcohol. It may then be separated as such from the organic solvent extract or in the form of an ester or as the copper salt the free acid can be recovered from the copper salt by H2S treatment. Purification is carried out by crystallization from concentrated water or alcohol solutions. Nyc et al. extracted nicotinic acid from the mycelium of Neurospora with acetone. Subsequent purification steps included the formation of the barium salt, acidification with H2SO4 and adsorption of the free nicotinic acid on charcoal. Elution was accomplished with 4% aqueous aniline and the final purification step involves recrystallization from a i 4 mixture of acetic acid and benzene. Leifer et al. have applied paper chromatography with M-butanol saturated with ammonia to separate nicotinic acid from contaminating materials. 

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