Cyclopentyl methyl ether (CPME) has been developed as a commercially available ethereal solvent for application to various chemical processes. In the present study, the extraction of transition metal ions using di-(2-ethylhexyl) phosphoric acid (D2EHPA) in CPME and dodecane was studied in order to evaluate the potential of CPME as a diluent in the liquid-liquid extraction process. Transition metal ions were extracted by a proton exchange reaction using D2EHPA in CPME. The degree of extraction into CPME was reduced compared with dodecane. The extraction reaction of Cu(II) using D2EHPA in CPME and dodecane was confirmed by slope analysis. A 2 : 1 complex between dimeric D2EHPA and Cu(II) was formed in CPME and dodecane, and the extraction equilibrium constants were determined.
Solvent extraction of the group 4 elements Zr and Hf, homologues of Rf (Z = 104), by triisooctylamine (TIOA) from hydrochloric acid (HCl) was performed by batch method using carrier-free radioisotope tracers. The times required to reach equilibria were determined, and then variations of the equilibrium distribution ratios (D) were investigated against the TIOA and HCl concentrations. It was found that the chemical reactions involved in the extraction of the chloride complexes of Zr and Hf by 0.1–1.0 M TIOA from 7.4–10.4 M HCl reached equilibrium in 10–20 min. The D values increased as the concentrations of HCl and TIOA increased, suggesting the formation of anionic chloride complexes of Zr and Hf. We obtained comparison data to study Rf-chloride complex formation. Although the reaction time in the extraction needs to be shortened, the extraction behavior of Rf could be investigated by solvent extraction under the present experimental conditions.
The extraction and purification of copper by dithizone in kerosene from an aqueous chloride chalcopyrite leach liquor containing 934.44 mg/L Cu, 2326.73 mg/L Fe, 92.14 mg/L Mn, 0.65 mg/L Mg, 0.22 mg/L Ca, 0.076 mg/L Sn and 0.011 mg/L Pb was investigated. The effects of extractant concentration and pH of aqueous media on the total copper extraction were studied. The results of fundamental studies on solvent extraction of synthetic solutions of Cu(II) showed that metal ion extraction increased with increasing pHand extractant concentration. The leach liquor purification was firstly done by total precipitation of iron and manganese using Ca(OH)2 and H2O2 as oxidizer at pH 3.58 and 4.25, respectively. An extraction efficiency of 97.3% total copper was obtained by 0.2 mol/L dithizone in kerosene at 25±2 oC within 30 minutes at pH 5.0. A 0.1 mol/L HCl solution was found to be adequate for the stripping of about 98.3% Cu from the loaded organic phase. The stripped copper solution was recovered as copper oxide (Tenorite, CuO : 05- 0667) via precipitation with sodium hydroxide followed by calcination at 600 oC for 120 minutes. Finally, an operational scheme summarizing the extraction procedure to obtain a high grade copper compound was presented.
In this study, aqueous two-phase systems of polyethylene glycol 2000/C4O6H4KNa and polyethylene glycol 2000/Na2SO4 were investigated for the extraction of extract microcystin-LR. These two aqueous two-phase systems were optimized by varying the molecular weight of polyethylene glycol, the concentrations of polyethylene glycol 2000, the inorganic salts, added ionic strength, rotation speed and the pH value. The results showed that higher recovery could be achieved by an aqueous two-phase system of polyethylene glycol /Na2SO4 when compared with an aqueous two-phase system of polyethylene glycol /C4O6H4KNa. The recovery of microcystin-LR can reach about 60.6% under the optimum extraction conditions [polyethylene glycol 2000 8%(w/w), C4O6H4KNa 9%(w/w), added ionic strength I=0, rotation speed 4000r/min, pH=5].
The process of leaching copper from malachite using methane-sulfonic acid (MSA) as an organic leaching reagent was investigated in this study. The effects of acid concentration, reaction temperature, particle size, and stirring speed on the copper leaching fraction were determined. Results indicated that leaching reagent concentration and reaction temperature exerted significant effects on copper extraction, whereas particle size and stirring speed exerted a relatively minor effect on the leaching rate. The kinetics of the dissolution process followed the shrinking core model, and a new kinetic model was found suitable to represent the rate-controlling step. The apparent activation energy of this process was determined to be 24.48 kJ/mol, and a semi-empirical rate equation was obtained to describe the process.
The development of efficient methods for the removal of organic dyes, which are considered to be toxic to the aquatic biota and therefore destroy the ecosystem, is required. In this study, the extraction of methylene blue (MB) from aqueous solution into DEHPA/isooctane solution was investigated. MB was hardly extracted at all from the aqueous to the organic phase at pH values below 5, and the extraction ratio of MB greatly increased with increasing pH in the range of 5-6 by the electrostatic attraction between dissociated DEHPA and MB. MB was not extracted to the organic phase at pH values above 6, since DEHPA leaked from the organic to the aqueous phase. The addition of 2-ethyl-1-hexanol suppressed the DEHPA leakage, and then MB was successfully extracted to the organic phase at pH values above 6. It was found that MB was solubilized as an MB-DEHPA complex in the organic phase in the pH range of 5-5.5, whereas MB would be entrapped in the waterpool of the reversed micelle at pH values above 5.5. The back extraction ratio of MB from the organic to the aqueous phase was about 100 % at pH values below 5 because of the destruction of the reversed micelles and the disappearance of the electrostatic attraction between DEHPA and MB.
The extraction of apigenin and luteolin from the alfalfa leaves; Medicago sativa (L.) using mixtures of liquid carbon dioxide (CO2) was performed at 5, 20 and 25 ºC. The extraction pressure was from 8.5 to 14 MPa. The extraction yields were compared with yields obtained by other solvent extraction methods, such as pure liquid CO2 extraction and conventional alcohol (methanol or ethanol) extraction. We conducted qualitative and quantitative analyses for luteolin and apigenin in the extract using HPLC and analyzed the extraction behavior. The effect of three operating parameters, temperature, pressure and composition of ethanol in the liquid CO2 solution, on the extraction yield was investigated using the single-factor method. The yields of luteolin and apigenin in the extraction were significantly improved by adjusting the operating temperature and amount of ethanol in the liquid CO2 solution, whereas a change in the selectivity of the extract was not observed.
The liquid carbon dioxide (CO2) extraction of xanthones, such as α-mangostin from the pericarp of mangosteen (Garcinia mangostana Linn.), was enhanced using ultrasound at 5, 20 and 25 ºC. Mixtures of carbon dioxide and ethanol were used as solvents. The extraction pressure was from 8 to 14 MPa. To enhance the extraction yield, the solvent was irradiated with ultrasound. The yields of xanthones, such as α-mangostin, in the extraction were significantly improved without any change in the selectivity of the extract. We also qualitatively and quantitatively analyzed the xanthones in the extract using HPLC (high-performance liquid chromatography) as well as the extraction behavior. The effect of four operating parameters, temperature, pressure, ultrasound irradiation time and the composition of ethanol in the liquid CO2 solution, on the extraction yield was investigated using single-factor experiments. The improved ratio in yields of each xanthone between the ultrasonic-enhanced case and unenhanced case was calculated. The yields of xanthones in the extract were significantly improved by adjusting the operating temperature, ultrasound irradiation time and the composition of ethanol in the liquid CO2 solution, whereas no change in the selectivity of the extract was observed.
The synergism caused by of six β-diketones on the extraction of gallium(III) with di(2-ethylhexyl)phosphoric acid (D2EHPA or HA) from weak acidic solution into heptane and supercritical carbon dioxide (SC-CO2) was investigated. Thenoyltrifluoroacetone (Htta), benzoylacetone (Hbza), benzoyltrifluoroacetone (Hbfa), acetylacetone (Hacac), trifluoroacetylacetone (Htfa), and hexafluoroacetylacetone (Hhfa) were used as synergists. In the heptane extraction with 5.0 × 10−3 M D2EHPA and 5.0 × 10−4 M β-diketone, synergism occurred in the presence of Htta, Hbza, Hhfa, Hbfa and Htfa, but not to any extent with Hacac or Hbza. The synergistic effect increased in the following order: Htfa < Hhfa < Hbfa ≈ Htta. The synergistic extraction equilibrium of gallium(III) with D2EHPA and Htta in heptane was investigated. The results suggest that two types of complexes were extracted with D2EHPA and Htta, namely GaA2(tta)·HA and GaA2(tta)·2HA. This synergistic effect also occurred in SC-CO2 extraction. However, the degree of synergism in the SC-CO2 system is smaller than that in the heptane system.
The biological production of 1,3-propanediol from glycerol, which is a by-product in a bio-diesel production process, is of great interest. However, major difficulties still exist in downstream processing because 1,3-propanediol has a high boiling point. In this study, reactive extraction with aldehydes in the presence of a hydrophobic acidic ionic liquid as an acidic catalyst was used to extract 1,3-propanediol from an aqueous solution. Hydrophobic acidic ionic liquids have successfully played the role of acidic catalysts for acetalization as well as hydrochloric acid. Aromatic compounds as diluents were preferable for this acetalization. Conversion of 60 g/dm3 of 1,3 propanediol reached 96% at a concentration of 4.0 mol/dm3 of 1-butanal in toluene.
Ultrasonic waves (USW) are often applied in order to clean the surface of items such as glass ware and also to help dissolving chemicals in water or solvents. It is well known that USW produced in a fluid create a series of compression waves and partial vacuum bubbles are formed and collapse releasing extremely high energy. Here we report that a simple system consisting of only methanol (MeOH) and pure water sonochemically releases CO2 under agitation by USW. Application of USW caused immediate and continuous release of CO2 from a MeOH/water mixture. At 23 and 43 kHz, the optimal MeOH concentration for CO2 production was 3 and 10% (v/v), respectively. Among 4 alcohols examined, MeOH was shown to be most suitable for production of CO2, suggesting that longer alkyl chains may significantly reduce participation in the reaction with water under USW. Since ascorbate and two different scavengers of hydroxy radicals (HO˙) lowered the rate of CO2 production, sonochemical reactivity under USW can be largely attributed to the generation of HO˙. We believe that this phenomenon is noteworthy since MeOH is frequently employed as a solvent for extraction of various compounds from agricultural and biological materials and USW are also often applied for biochemical preparations without having the possibility of the solvents unexpectedly reacting under USW.