Solvent extraction processes extractants used

Caprolactam Extraction. A high degree of purification is necessary for fiber-grade caprolactam, the monomer for nylon-6 (see Polyamides). Cmde aqueous caprolactam is purified by solvent extractions using aromatic hydrocarbons such as toluene as the solvent (233). Many of the well-known types of column contactors have been used a detailed description of the process is available (234). 

A process developed in Israel (263) uses solvent extraction using a higher alcohol or other solvating solvent. This removes phosphoric acid and some hydrochloric acid from the system driving the equiHbrium of equation 42 to the right. The same principle can be appHed in other salt—acid reactions of the form... 

Israel Mining Industries developed a process in which hydrochloric acid, instead of sulfuric acid, was used as the acidulant (37). The acidulate contained dissolved calcium chloride which then was separated from the phosphoric acid by use of solvent extraction using a recyclable organic solvent. The process was operated commercially for a limited time, but the generation of HCl fumes was destmctive to production equipment. 

Cesium isotopes can be recovered from fission products by digestion in nitric acid, and after filtration of waste the radioactive cesium phosphotungstate is precipitated using phosphotungstic acid. This technique can be used to prepare radioactive cesium metal or compounds. Various processes for removal of Cs isotopes from radioactive waste have been developed including solvent extraction using macrocycHc polyethers (62) or crown ethers (63) and coprecipitation with sodium tetraphenylboron (64). 

Several techniques can be used to separate phenol. Solvent extraction using gas oil or lube oil (process MSAs Sj and S2, respectively) is a potential option. Besides the purification of wastewater, the transfer of phenol to gas oil and lube oil is a useful process for the oils. Phenol tends to act as an oxidation inhibitor and serves to improve color stability and reduce sediment formation. The data for the waste streams and the process MSAs are given in Tables 3.4 and 3.5, respectively. 

Reddy, B. R. Parija, C. Sarnia, P. Processing of solutions containing nickel and ammonium sulphate through solvent extraction using PC-88A. Hydrometallurgy 1999, 53, 11-17. 

ENSR International Group soil cleaning process is an ex situ treatment for soils contaminated with petroleum hydrocarbons. The process uses a combination of soil washing and solvent extraction. Soil washing removes heavy metals and hydrocarbons from coarse soil particles, resulting in a reduced volume of material to be treated by solvent extraction. Solvent extraction uses a chemical additive that enhances the extraction of hydrocarbons from soil particles in an aqueous slurry. 

Nakahara, M., Sano, Y., Koma, Y., Kamiya, M., Shibata, A., Koizumi, T., Koyama, T. 2007. Separation of actinide elements by solvent extraction using centrifugal contactors in the NEXT process. Journal of Nuclear Science and Technology 44(3) 373-381. 

Kumar, A., Haddad, R., Alguacil, F.J. and Sastre, A.M. (2005) Comparative performance of non-dispersive solvent extraction using a single module and the integrated membrane process with two hollow-fiber contactors. Journal of Membrane Science, 248, 1. 

Solvent extraction has found application for many years in the coal tar industry. Extraction of phenols from coal-tar distillates by washing with caustic soda solution can be considered such a process. In the isomer separation, a process for separation of m- and p-crcsol by dissociation extraction has been reported. Work is in progress in several parts of the world to use solvent extraction for the direct manufacture of chemicals from coal. Crude tall oil is a byproduct of pulp mills. It is refined by solvent extraction using propane or furfural. 

Copper is widely distributed in Nature as metal, in sulfides, arsenides, chlorides, carbonates, and so on. It is extracted from ores, usually by wet processes, for example, by leaching with dilute sulfuric acid, or by solvent extraction using salicylal-doximes and similar ligands. Copper is refined by electrolysis. 

In Chapters 1, 2, and 5 we discussed the term membrane solvent extraction or solvent extraction using membrane contactors. It is a part of BOHLM systems, constructed using hoUow fiber or capiUary membranes forward and back extraction combined in one unit or in two units separately, as shown in Fig. 9.7. In the last decade many researchers presented this process and devices as a specific. We discuss it here as one of the BOHLM systems. 

A number of literature reviews of liquid-liquid extraction of antibiotics (12), small molecules (13), and biopolymers (14) have been published. The goal of this section is to give practical instructions for developing solvent extraction for a laboratory-scale process. Several examples of solvent extraction using... 

The different purification methods tested on the mussel extracts were based on solvent extractions using chloroform, diethyl ether or petroleum ether, passage through a Cig cartridge, dilution or filtration. Lower values obtained for arsenobetaine were attributed to calibration errors or losses during the clean-up process. Higher values were certainly due to calibration or interferences (co-elution of an unknown compound with arsenobetaine). 

Materials templated with polymeric surfactants can also be successfully solvent extracted using ethanolJ It has been shown that the templating surfactant can be recovered after solvent washing, and used to synthesise further mesoporous materials. This recycling of surfactant reduces the costs of making these materials, and would also be environmentally beneficial in industrial production processes. The main drawback of solvent... 

The chemical process we have chosen is solvent extraction using 1.5% TBP in Amsco. We chose this sytem over the Hexone system presently used at Arco because it is more flexible and does not require the precise concentration adjustment typical of Hexone. Laboratory studies and pilot experience show that adequate decontamination can be obtained with TBP iii one extraction cycle. 

In the HCl leaching system, 99% of rare earth was leached under the condition of 3 or 4 kmol/m HCl at 95 °C in the 3-h reaction time (Tzanetakis and Scott, 2004a Zhang et al., 1998). The solvent extraction using D2EHPA was introduced into the separation of rare earth from the HCl leaching solution. Zhang et al. (1998) proposed the metal separation process on the basis... 

In conventional chemical processing of vegetable oils, crude oil is recovered from the mechanically expressed vegetable seed by solvent extraction using hexane, as shown in Figure 3.14 [22]. The misceUa (a mixture of extracted oil and solvent) from the extractor contains 60—70% solvent, which is recovered by distillation and reused. Purification of crude oil consists of removing components that are harmful and are not wanted in the final product, the pure oil. These components are phosphatides (gums and lecithin). 

Three steps required for multistage solvent extraction, i.e., phase mixing, phase settling, and transfer of the mobile phase, are defined clearly in the discontinuous countercurrent distribution process using the Craig apparatus. These basic requirements are essentially fulfilled by the use of a coiled tube in a continuous fashion. Solvent extraction using a coiled column is most efficiently performed with a horizontally laid coil that rotates about its own axis. In this horizontal coil orientation, the rotation induces the well known Archimedean screw force, which can be utilized for performing countercurrent solvent extraction. 

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