Optimization of Some Parameters on the Low Efficiency of Solvent Extraction of Uranium with Alamine 336

Solvent extraction of uranium from sulfate liquor acid ore with Alamine 336 from two suppliers has been studied. The influence of various parameters, such as sulfuric acid concentration on uranium bearing solutions, concentration of Alamine 336, and concentration of uranium was investigated. The decrease of uranium efficiency extraction at the plant was caused by the degradation of the organic phase. Degradation caused by the presence of vanadium in the uranium ore. Two theoretical stages could efficiency extract more than 90% of uranium from a solution containing 3881 mg/L at O/A ratio of 1.5:1. At the range of sulfuric acid concentration of 0.1 M to 0.2 M, Uranium efficiency was enhanced from 89% to 92 at the 1st contact and from 18% to 20% at the second contact. At this range of concentration, the UO2(SO4)2/2 species predominate. For sulfuric acid concentrations over 0.2 M the uranium efficiency decreased due to the presence of UO2(SO4)2/2 and UO2(SO4)3/4 species. Improving volume percentage of Alamine 336 in organic phase enhanced the uranium efficiency to 99%.

Comparison of Extraction Ability between a Mixture of Alamine 336/Aliquat 336 and D2EHPA and Ionic Liquid ALi-D2 from Weak Hydrochloric Acid Solution

The development of extraction systems to improve the extraction efficiency of metals using commercial extractants and ionic liquids is of importance. The extraction behavior of Co(II) between mixture of Alamine 336/Aliquat 336 and D2EHPA and synthesized ionic liquid ALi-D2 was compared in this work. Some factors, such as equilibrium pH, properties of the extractants, and concentration of components in the mixture had a remarkable effect on the extraction of Co(II). The interactions occurring in the mixtures as well as the change in solution pH were analyzed. Co(II) was completely extracted by ionic liquid when equilibrium pH was higher than 6.5, while it was difficult to extract Co(II) by employing the mixture of D2EHPA and Alamine 336/Aliquat 336. The formation of ionic liquid in the mixture of D2EHPA and Aliquat 336 was verified through FT-IR spectra. In addition, the competition extraction of hydrogen ion and Co(II) by ionic liquid ALi-D2 was explained. Among the three kinds of extractants, the ionic liquid showed the best extraction efficiency for Co(II) and pH control from weak acidic solutions. The present study provides valuable information on the extraction behavior of metal ion by the mixtures of commercial extractants, and thus can give some light on the development of metal extraction systems.

Investigations on the complete removal of iron(III) interference on the uranium(VI) extraction from sulfate leach liquor using Alamine 336 in kerosene

Uranyl sulfate obtained by uranium ore leaching of an industrial sample deposit of Gachin site was used for uranium separation by the solvent extraction technique. The presence of other elements in the sulfate leach liquors has a negative impact on the uranium extraction process using Alamine 336; therefore, the operating costs are increased. In this study, the separation of uranium(VI) and iron(III) by Alamine 336 and kerosene have been examined as an extractant and a diluent, respectively. For this purpose, the effects of operating parameters on the extraction process such as Alamine 336 concentration, modifier concentration, contact time, initial aqueous pH, sulfate ion concentration, temperature, and stripping agents were investigated. Also, the complete removal of iron(III) interference from the sulfate leach liquor before the extraction step has been studied with reducing agents. The equilibrium constants and stoichiometric coefficients for uranium and iron extraction with Alamine 336 in the sulfate leach liquors were calculated. Likewise, the values of the thermodynamic parameters such as Gibbs energy, enthalpy and entropy were determined to prove the exothermic and spontaneous reactions. The mentioned procedure is proposed for the uranium separation from the impurities in the sulfate ores using tertiary amine for production of purified uranium.

Emulsion breakage behaviour on chromium (VI) removal using emulsion liquid membrane containing quaternary ammonium compounds

Environmental pollution caused by heavy metals such as chromium, nickel, and lead has become a serious worldwide issue due to their threats to humans, animals and plants as well as to the stability of the overall ecosystem. Its removal from effluents such as electroplating rinse wastewater and tannery effluents is of primordial importance. In this study, the emulsion liquid membrane (ELM) technology was employed as a remediation technique that capable of removing Cr (VI) efficiently from wastewater where extraction and stripping processes are performed in a single operation. The ELM is consists of trioctylmethylammonium chloride (Alamine 336) as an extractant, palm oil as an organic diluent, sodium hydroxide (NaOH) as a stripping solution and sorbitan monooleate (Span-80) as a surfactant to stabilize the emulsion phase. The effect of operational parameters such as the agitation speed, phase contact time, extractant concentration and stripping agent concentration were studied to optimize the conditions for emulsion stability and maximum removal of chromium. The best removal efficiency was obtained at 350 rpm of agitation speed and 3 minutes of phase contact time with 0.04 M Alamine 336 as extractant and 0.1 M NaOH as stripping agent. In this condition, the maximum removal efficiency of 100% was obtained with a minimum breakage rate of 5%.