Solvent extraction mechanism

Itagaki, M. Fukushima, H. Inoue, H. Watanabe, K. Electrochemical impedance spectroscopy study on the solvent extraction mechanism of Ni(II) at the water 1,2-dichloroethane interface. J. Electroanal. Chem. 2001, 504, 96-103. 

It is the primary intent of this book to teach readers how the chemistry of polyurethanes can be used to advantage. As we will show in a later chapter, the current polyurethane chemistries are effective for removing certain classes of organic molecules from the environment via a solvent extraction mechanism. The material presented above is useful for building an appropriate polymer system. 

We sponsored a study by the environmental laboratory of tlie University of Maine in Orono. The study deteimined that HPUR had the capacity to extract about 3.5 mg of MtBE per gram of hydrophilic foam. The university and others attributed this to a solvent extraction mechanism based on the fact that the extraction units are noted in milligrams per gram of foam. If the reaction were purely a surface phenomenon, the units would have been stated in milligrams per unit of area. 

PA-6 (90) / EPDM-g-MA (10) or EP-g-MA or PE-g-MA SSE / selective solvent extraction / mechanical properties / morphology / dilatometry tests / also used unfunct ionaUzed. poly(etherester) TPE Borggreve et al., 1989 a, b... 

TSE at 280°C / selective solvent extraction / mechanical properties / Campbell et al., 1990 ductile-brittle transition temperatures / SEM / TEM SSE at 275°C / X-ray diffraction for compositional analysis and Murthy et al., 1990... 

PC (95-50) / HOPE (0-20) / EMAA ionomer (5-50) internal mixer at 220°C / torque rheometry / FTIR / DSC / selective solvent extraction / mechanical properties / SEM Mekhilefcia/., 1992... 

Campbell et al. [1990] have reported properties for compatibilized PA-PPE blends made using anhydride-terminated PPE. A block copolymer may form between PA amine end-groups and PPE-anhydride. For example, a blend containing 49 parts PPE-anhydride, 41 parts PA-6, and 10 parts SEBS impact modifier was extruded using a TSE at 280°C. The copolymer-containing blend was characterized by selective solvent extraction, mechanical properties, SEM, and TEM. Ductile-brittle transition temperatures were determined. Anhydride-terminated PPE was made by capping PPE phenolic end-groups with trimellitic anhydride chloride in solution. 

PA-6 (41)/PPE-g-MA (0-3 % MA) (49)/SEBS (10) TSE at 280 °C/selective solvent extraction/mechanical properties/ ductile-brittle transition temperatures/SEM/TEM Campbell et al. 1990... 

PET (48.5)/PPE (48.5)/ phosphoms tris(lactam) (3) SSE at 270-280 °C/copolymer level by selective solvent extraction/mechanical properties vs. without tris(lactam)/ different tris(lactams) used/PET-PC-PPE also studied Gians and Akkapeddi 1991a... 

PEI-PPE blends have also been compatibilized through copolymer formation between anhydride-functionalized PPE such as PPE-g-FA and amine-terminated PEI (White et al. 1989). Amine-terminated PEI was prepared from bisphenol A-diphthalic acid anhydride and m-phenylene diamine, the latter used in excess. Copolymer analysis was by selective solvent extraction. Mechanical properties and morphologies were compared to blends with unfunctionalized PPE and PEI. 

Recent research on the solvent extraction mechanism revealed that the role of liquid-liquid interface has to be taken into account for understanding the extraction mechanism, especially in the extraction kinetic mechanism. Breakthrough research has been attained with the invention of a high-speed stirring (HSS) method that made it possible to measure the interfacial concentration of extractant (Lewis base) and extraction rate of the complex. Thus, this technique could determine a rate law for the interfacial reaction for the first time [1],... 

Mechanical Pressing. Historically, the first large commercial production of oils from seeds and nuts was carried out using labor-intensive hydraulic presses. These were gradually replaced by more efficient mechanical and screw presses. Solvent extraction was developed for extraction of seeds having low oil content. For seeds and nuts having higher oil content, a combination of a screw press followed by solvent extraction is a common commercial practice (prepress—solvent extraction). 

Solvent extraction in batch or continuous systems is used to recover most of the residual oil from the presscake. Heptane, hexane, or a mixture of these solvents is used to recover the oil. The solvent-extracted presscake is steam stripped to recover solvent and a residual meal known as castor pomace, containing 1% residual oil. The solvent extracted oil is also processed for solvent recovery (qv). The oil from the extraction procedure is darker than the mechanically pressed oil and has a higher free fatty acid content. It is sometimes referred to as a No. 3 castor oil and is used for blending with higher quaUty oils that are well above No. 1 specifications. 

Chemical kinetics and mechanisms in solvent extraction of copper chelates. D. S. Flett, Acc. Chem. Res., 1977,10, 99-104(21). 

Kinetics and mechanism of metal chelation processes via solvent extraction techniques. H. Freiser, Acc. Chem. Res., 1984,17,126-131 (40). 

The authors have characterized the graft polymer by solvent extraction, transmission electron microscopy, dynamic mechanical analysis, mechanical testing (including measurement of tensile, tear, and impact strength), and morphology by SEM. The reaction scheme is given in Figure 11.25. 

Organic solvent extraction. Two analytical methods for acetamiprid have been developed One method is for the parent only and the other determines the total residue of the parent and its metabolites (lM-1-2, lM-1-4 and lC-0). Air-dried soil (20-g equivalent dry soil) is weighed into a centrifuge tube and imidacloprid residue is extracted with 100 mL of methanol-0.1M ammonium chloride (4 1, v/v) using a mechanical shaker for about 30 min. After shaking, the tube is centrifuged at 8000 rpm for 2 min. The supernatant is filtered and the analysis of the soil residue is carried out in the same manner as described above for the parent compound. 

Combine 50 g of the air-dried soil with 100 mL of acetone and shake the mixture with a mechanical shaker for 15 min. Filter the mixture through a fluted filter paper into a 500-mL flask. Wash the residue on the filter with 50 mL of acetone. Combine the filtrates and remove acetone by rotary evaporation. Transfer the residue with 150 mL of a potassium chloride solution into a separatory funnel, extract the solution with two portions of 50 mL of dichloromethane and collect the organic extracts in a flask. Filter the combined solvent extracts, together with the washings of the collecting flask, through anhydrous sodium sulfate into a 300-mL flask. Remove dichloromethane by rotary evaporation. Dissolve the residue in 10 mL of carbon tetrachloride. 

In the ion-association extraction systems, hydrophobic and interfacially adsorbable ions are encountered very often. Complexes of Fe(II), Cu(II), and Zn(II) with 1,10-phenanthro-line (phen) and its hydrophobic derivatives exhibited remarkable interfacial adsorptivity, although the ligands themselves can hardly adsorb at the interface, except for protonated species [19-21]. Solvent extraction photometry of Fe(II) with phen is widely used for the determination of trace amounts of Fe(II). The extraction rate profiles of Fe(II) with phen and its dimethyl (DMP) and diphenyl (DPP) derivatives into chloroform are shown in Fig.9. In the presence of 0.1 M NaC104, the interfacial adsorption of phen complex is most remarkable. The adsorption of the extractable complex must be considered in the analysis of the extraction kinetic mechanism of these systems. The observed initial rate r° shows the relation... 

Various types of research are carried out on ITIESs nowadays. These studies are modeled on electrochemical techniques, theories, and systems. Studies of ion transfer across ITIESs are especially interesting and important because these are the only studies on ITIESs. Many complex ion transfers assisted by some chemical reactions have been studied, to say nothing of single ion transfers. In the world of nature, many types of ion transfer play important roles such as selective ion transfer through biological membranes. Therefore, there are quite a few studies that get ideas from those systems, while many interests from analytical applications motivate those too. Since the ion transfer at an ITIES is closely related with the fields of solvent extraction and ion-selective electrodes, these studies mainly deal with facilitated ion transfer by various kinds of ionophores. Since crown ethers as ionophores show interesting selectivity, a lot of derivatives are synthesized and their selectivities are evaluated in solvent extraction, ion-selective systems, etc. Of course electrochemical studies on ITIESs are also suitable for the systems of ion transfer facilitated by crown ethers and have thrown new light on the mechanisms of selectivity exhibited by crown ethers. 

It was reported that neutral ionophore naphtho-15-crown-5 (N15C5, see Fig. 1) gives an excellent selective response to ion over Na+ ion when it is doped into an ion-selective electrode [2,3]. This result is very interesting considering the hole size of the crown. Ishibashi and coworkers studied the mechanisms of that selectivity using the technique of solvent extraction into 1,2-dichloroethane (DCE) where picrate anion was used as a counterion [4]. Their result is also interesting because Na+ is extracted as a... 

In liquid-solid extraction (LSE) the analyte is extracted from the solid by a liquid, which is separated by filtration. Numerous extraction processes, representing various types and levels of energy, have been described steam distillation, simultaneous steam distillation-solvent extraction (SDE), passive hot solvent extraction, forced-flow leaching, (automated) Soxh-let extraction, shake-flask method, mechanically agitated reflux extraction, ultrasound-assisted extraction, y -ray-assisted extraction, microwave-assisted extraction (MAE), microwave-enhanced extraction (Soxwave ), microwave-assisted process (MAP ), gas-phase MAE, enhanced fluidity extraction, hot (subcritical) water extraction, supercritical fluid extraction (SFE), supercritical assisted liquid extraction, pressurised hot water extraction, enhanced solvent extraction (ESE ), solu-tion/precipitation, etc. The most successful systems are described in Sections 3.3.3-3.4.6. Other, less frequently... 

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