Organic acids recoveries

Tests were performed with both simulated broth containing succinic acid at various concentrations and actual broth provided by MBI. Seven resins were tested for regenerability and stability with acid XUS 40285, Dowex 1x2, XUS 40283, XUS 440323, XFS-40422, IRA-35, and IRA-93. Previous results had shown a decrease in capacity with repeated hot water regeneration. It is essential for economical operation that the organic acid recovery be >90% and that the sorbents be stable for at least 20 cycles (based on industrial comments). Several resins were tested for stability with a single-step dilute-acid regeneration. The resins were either low capacity after five cycles or had incomplete recovery of the succinic acid (data not shown). Therefore, we modified the procedure to extract the succinic acid first with dilute base, then hot water. 

BPMs offer a solution to the cation elimination problem accompanying most organic acids They allow a salt to be split into the corresponding alkali and acid solutions. Consequently, BPMs are used in water-splitting processes and offer possibilities for organic acid recovery from fermentative production. In addition, the decrease in ionic strength induced by cation demineralization coupled with acidification of the solution was also used for the production of phospholipids. 

Organic acid recovery (specialty chemical Organic acid production (specialty chemical Organic acid production (France)... 

B. R. Smith, "Organic Acid Recovery with Coupled-Transport Membmues," paper presented at... 

The oil industry uses microencapsulated oil-field chemicals. For example, microencapsulated breaker is deHvered into a subterranean formation where it breaks the fracturing Hquid used to stimulate the recovery of fluids such as cmde oil or natural gas. Examples of breakers encapsulated include oxidi2ers, en2ymes, and various mineral or organic acids. 

Water Splitting A modified electrodi ysis arrangement is used as a means of regenerating an acid and a base from a corresponding salt. For instance, NaCl may be used to produce NaOH and HCl. Water sphtting is a viable alternative to disposal where a salt is produced by neutralization of an acid or base. Other potential applications include the recovery of organic acids from their salts and the treating of effluents from stack gas scrubbers. The new component required is a bipolar membrane, a membrane that sphts water into H and OH". At its simplest, a bipolar membrane may be prepared by... 

In this solvent the reaction is catalyzed by small amounts of trimethyl-amine and especially pyridine (cf. 9). The same effect occurs in the reaction of iV -methylaniline with 2-iV -methylanilino-4,6-dichloro-s-triazine. In benzene solution, the amine hydrochloride is so insoluble that the reaction could be followed by recovery. of the salt. However, this precluded study mider Bitter and Zollinger s conditions of catalysis by strong mineral acids in the sense of Banks (acid-base pre-equilibrium in solution). Instead, a new catalytic effect was revealed when the influence of organic acids was tested. This was assumed to depend on the bifunctional character of these catalysts, which act as both a proton donor and an acceptor in the transition state. In striking agreement with this conclusion, a-pyridone is very reactive and o-nitrophenol is not. Furthermore, since neither y-pyridone nor -nitrophenol are active, the structure of the catalyst must meet the conformational requirements for a cyclic transition state. Probably a concerted process involving structure 10 in the rate-determining step... 

Table 2 Recovery of Water Extractable Organic Acids Applied to a P-deficient West African Soil Taken from the Culture Vessels of Haketi imdulata ...

Increasing the water-wet surface area of a petroleum reservoir is one mechanism by which alkaline floods recover incremental oil(19). Under basic pH conditions, organic acids in acidic crudes produce natural surfactants which can alter the wettability of pore surfaces. Recovery of incremental oil by alkaline flooding is dependent on the pH and salinity of the brine (20), the acidity of the crude and the wettability of the porous medium(1,19,21,22). Thus, alkaline flooding is an oil and reservoir specific recovery process which can not be used in all reservoirs. The usefulness of alkaline flooding is also limited by the large volumes of caustic required to satisfy rock reactions(23). 

In the presence of soluble cations (e.g. Fe, Cu), additions of small quantities of organic acid (e.g. oxalic, tartaric) improve gold recovery in the copper concentrate. 

In recent years, a new line of hydrophobic gangue depressants were developed, based on a mixture of guar gums and low-molecular-weight polyacrylates modified with organic acid, which are extremely effective. With the use of these depressants, the grade of the PGM concentrate could increase from 100 up to 40 g/t without any loss in recovery. 

In recent years, a number of alternative activators were examined. It was found that organic acids along with a mixture of organic acid and thiourea can replace CuS04 with significant improvement in PGM recovery and selectivity. The results obtained using different activators on the Morensky Operation B ore are compared in Table 18.3. 

The highest PGM recovery was achieved using collector PM443, which is an amine + ester-modified xanthate. Among the chromium slime depressants evaluated, modified mixtures of organic acids, RQ depressants and a low-molecular-weight polyacrylic acid + pyrophosphate mixture were there. The effect of different chromium depressants on chromium assays of the PGM concentrate are illustrated in Figure 18.7. 

Chen et al. (1997a) analysed sodium saccharin in soft drinks, orange juice and lemon tea after filtration by injection into an ion-exclusion column with detection at 202 nm. Recoveries of 98-104% were obtained. They reported that common organic acids like citric and malic and other sweeteners did not interfere. Qu et al. (1999) determined aspartame in fruit juices, after degassing and dilution in water, by IC-PAD. The decomposition products of aspartame, aspartic acid and phenylanaline were separated and other sweeteners did not interfere. The recoveries of added aspartame were 77-94%. Chen et al. (1997b) separated and determined four artificial sweeteners and citric acid. 

Figure 6.23 Flotation recovery of lime-depressed pyrite activated by organic acids vs. concentration of activators...

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