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The primary goal of this study was the development of a recycling process to recover titanium from real sulfate leach liquors prepared from the tailings of uranium processing mine. Preparation and characterization of pure TiO2 powders using; a clean, cheap, and low-temperature combined solvent extraction/electrochemical deposition technique were reported. Solvent extraction using di(2-ethylhexyl) phosphoric acid in kerosene allowed the selective recovery of Ti (IV) from the leach liquor containing Fe, Mn, and Zr impurities. All of the Ti was extracted selectively using 20% D2EHPA/kerosene under organic/aqueous phase ratio of unity in presence of L-ascorbic acid. The equilibrium in 8.5 M sulfuric acid is established within 60 min. Subsequently, Ti was recovered from the loaded organic phase using mixtures of HCl and H2O2 solutions. The preparation of TiO2 powders by cathodic electrodeposition was optimized. A combination of X-ray diffraction and dynamic light scattering analysis had been used to confirm the formation of TiO2 nanoparticles. Finally, the solvent extraction and electrodeposition mechanisms were discussed, and the resultant products were characterized by several techniques. [ABSTRACT FROM AUTHOR]

The main aim of the present work is to prepare a natural extractant from the Egyptian plant remains, banana peels. The latter were chosen because they are considered among the popular and widespread plant wastes in Egypt. In this study, banana peels were investigated as a solvent to extract uranium ions from sulfate leach liquor. A synthetic sulfate solution was firstly conducted to optimize the extraction conditions. The work was then oriented to extract uranium from Abu Thor ore sulfate leach liquor. Finally, the results proved that uranium can be efficiently recovered from its sulfate solution using banana peels extractant. [ABSTRACT FROM AUTHOR]

In order to alleviate the sulfate accumulation in uranium hydrometallurgy process, the sulfate accumulating path was studied and a new elution process was proposed. The eluate composition as a function of eluent volume during the conventional and new elution process was studied. The result showed that pre-elution of saturated resin with 0.5–0.8 BV (bed volume) mother liquor was beneficial to the discharge of accumulated sulfate and could alleviate the accumulation of sulfate. Field tests showed that the new process ensured more stable production and reduced the amount of wastewater. Finally, the mechanism of the pre-elution process was analyzed. [ABSTRACT FROM AUTHOR]

This work claims the use of the mixture of Primene®JMT-Versatic 10 [HJMT+·Versatic−] IL diluted in Kerosene as an extractant for cobalt/nickel separation from sulphate media by solvent extraction technique, its application on a continuous counter-current device is possible because the presence of Primene®JMT in the organic phase allows us to maintain the pH of the equilibrated aqueous phase at an almost stable value. The solvent extraction of cobalt and nickel ions is studied as a function of the extractant concentration in the organic phase and the concentration of both metals. By constructing the McCabe–Thiele diagram, we found that four steps are necessary to separate the cobalt(II) from the nickel(II) in sulphate media. A simulated continuous counter-current experiment corroborated the McCabe–Thiele predictions, obtaining a raffinate containing 83% of the inlet nickel with a purity of 99.9%, working with an A:O ratio 1:2. [ABSTRACT FROM AUTHOR]

The impregnation of rice straw with 2-amino-3-(2-(4-chlorophenyl)hydrazinyl)-8,8-dimethyl-8,9-dihydropyrazolo[1,5-a]quinazolin-6(7H)-one (CPHPQ) has been used for the recovery of uranium from sulfate leach liquor. The uranium adsorption and elution of solvent impregnated mercerized rice straw (SIMRS) were carried out using a batch technique. The uranium adsorption controlling factors include pH, initial uranium concentration, contact time, S/L ratio, and temperature. Thermodynamic characteristics showed that the adsorption process is exothermic with enthalpy change ΔH = −152.1 kJ/mol. The kinetics data fit well with a pseudo-second-order model. The equilibrium data fit well with the Langmuir isotherm. Uranium cake was obtained from the eluate solution using hydrogen peroxide as UO4.2H2O precipitate. [ABSTRACT FROM AUTHOR]

The application of an integrated process configuration comprising of an ion exchange (IX) column and an upflow anaerobic sludge blanket (UASB) bioreactor for the simultaneous removal of SO42- and total Se from synthetic mine wastewater was evaluated. Use of an IX column as a pre-treatment (not as post-treatment) to the UASB bioreactor gave the best overall removal performance. The combined treatment reduced the total Se and SO42- concentration from 8.0 and 1441 mg/L to 0.2 and 28.0 mg/L, respectively. This study demonstrated for the first time that an IX process as a pre-treatment to a biological process can significantly improve the oxyanion removal efficiency and the overall treatment of Se-laden wastewaters. [ABSTRACT FROM AUTHOR]

In this study, waste rock of iron ore mine (metasomatic rocks) has been modified and utilized as a sulfate adsorbent to enhance sulfate removal from contaminated aqueous solution. The modification generating from the assembly of Mg-Al and Ni-Al layered double hydroxides and metasomatic rocks. The sulfate adsorption onto both adsorbents was performed favorably as a monolayer adsorption in homogeneous condition. The kinetic studies identify the chemisorption mechanism of sulfate adsorption process onto both adsorbents with the combination of the film-mass transfer and internal diffusion. Thermodynamic studies indicate that sulfate adsorption process onto both adsorbents was exothermic and spontaneous. [ABSTRACT FROM AUTHOR]

A newly synthesized chitosan stearoyl thiourea derivative is first used for the preconcentration of uranium from sulfate solution prior to its spectrophotometric determination. The effect of optimal adsorption and elution conditions was studied. The equilibrium data were found to be satisfactorily fitting to Langmuir isotherms with a maximum adsorption capacity of 98.75 mg/g. Kinetics and thermodynamics studies showed an exothermic pseudo-first-order adsorption process. Interference studies showed a high tolerance of diverse ions. The proposed method was validated and successfully applied for the determination of uranium in certified reference samples and ore samples with satisfactory results. [ABSTRACT FROM AUTHOR]

A polymer–salt aqueous two-phase system based on polyethylene glycol and sulfates was applied to explore the partition behavior of spiramycin. Binodal curves were measured by the turbidimetric titration method. The influence of temperature, salt concentration, and pH on the distribution behavior was investigated in detail by determining the partition coefficient and extraction efficiency. As pH and salt concentration increase, the partition coefficients increase accordingly. It was found that pH displays a significant influence on the partition behavior. The partition coefficient and extraction efficiency can reach 42.46 and 97.8%, respectively, at pH 9.0 and 15.80% (w/w) salt concentration. [ABSTRACT FROM AUTHOR]

Separation of cobalt and nickel from sulfate media was investigated, using a extraction system of 30% 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (P507)+15% trioctyl/decylamine (N235)+55% sulfonated kerosene. About 41 wt% Co2+was extracted with 1.6 wt% co-extraction of Ni2+at O/A ratio of 2:1. Scrubbing of Ni2+and stripping of Co2+could be achieved from the loaded organic phase, using water and 0.05 mol/L H2SO4, respectively. Cobalt extraction percentage decreased with increasing Mg2+concentration, but this influence was negligible as [Mg2+] < 0.1g/L. The favorable equilibrium pH was 4–4.8. A different E-pH curve was observed in the P507-N235 system compared to the saponified P507 system. [ABSTRACT FROM AUTHOR]

A fully ionized polyelectrolyte was synthesized for Cr(VI) removal from aqueous solutions by continuous polymer enhanced ultrafiltration (PEUF). Effect of operating parameters such as pH, loading, polymer, and competing ion concentrations were examined. Highest Cr(VI) retention was obtained at a loading of 0.01 at pH 4. Increasing both polymer and chromate concentrations at a fixed loading of 0.01 decreased the retention which demonstrated the effect of crowding. In the presence of competing anions such as chloride and sulfate, Cr(VI) retention decreased for all of the pH values studied. Even at high competing anion concentrations, significant retentions of Cr (VI) were obtained. [ABSTRACT FROM AUTHOR]

The films with the extreme concentration of poly (diallyldimethylammonium chloride)/sodium dodecylsulfate complex spread to the surface of aqueous solutions of formic and acetic acids reduce the evaporation rate of liquids by 3–6% and demonstrate selective properties increasing water content in the vapor by 1–3 abs.%. The concentrations of solutions were up to 30 vol.%. The formation conditions of such films were determined by means of the Wilhelmy plate technique. Surface tension isotherms of aqueous solutions of acids were also obtained. [ABSTRACT FROM AUTHOR]

Lime neutralization is widely used to precipitate heavy metals including copper and cobalt from wastewater. Limestone (calcium carbonate: CaCO3) is too stable to be used directly for this purpose. Grinding of CaCO3in the solutions of copper and cobalt sulphate was conducted to raise its reactivity. During the mechanochemical activation, CaCO3reacted with copper sulphate but not significantly with cobalt sulphate and this phenomenon allowed an easy separation of copper from cobalt. The residual of Cu(II) ions in solution could be controlled at less than 0.1%, meanwhile more than 90% of the Co(II) ions remained in aqueous solution. [ABSTRACT FROM AUTHOR]

Separation of nickel(II) and cadmium(II) ions with use of ion-exchange resins—Amberlyst 15 and Lewatit OC 1026—supported liquid membranes (SLM), polymer inclusion membranes (PIM) and ion-exchange membranes (IM) from sulphate solution has been studied. Di(2-ethylhexyl) phosphoric acid (D2EHPA) was used as the ion-carrier in PIM and SLM separation. It was shown that use of SLM or PIM membranes enables separation of Ni(II)/Cd(II) ions. Experimental results data show that the highest recovery factor values were obtained for supported liquid membranes. The SEM surface and cross-sectional images of SLM support, polymer inclusion membrane and ion-exchange membrane have been also prepared. [ABSTRACT FROM PUBLISHER]

The extraction of propionic acid has been studied by liquid–liquid extraction with poly ethylene glycol /different salts of sulfate aqueous two-phase system (ATPS). In this study, a multilevel factorial design was applied to evaluate the effects of four independent variables (PEG molecular weight, type of salt, salt concentration, and temperature) on propionic acid extraction yield. The statistical significance of each factor was evaluated by an analysis of variance. The results indicated that the type and concentration of salt were the major contributing factors to propionic acid extraction. The PEG4000/ MnSO4system was suitable for the extraction of propionic acid from dilute water. [ABSTRACT FROM AUTHOR]

Separation of nickel(II) and cadmium(II) ions from sulphate solution with use of supported liquid membranes (SLM) has been studied. Di(2-ethylhexyl)phosphoric acid (D2EHPA) dissolved in kerosene was used as the ion carrier. Obtained data were compared with data from polymer inclusion membranes (PIM) experiments. It was shown that use of SLM membranes enables separation of Ni(II) and Cd(II) ions. Experimental results data show that faster transport and higher recovery factor values were obtained for supported liquid membranes. [ABSTRACT FROM PUBLISHER]

The solvent extraction of Ti(IV) from sulfate medium by the commercial extractant Cyanex 301 (HA) has been studied in order to examine this novel system. Heptan-1-ol (5% (v/v) in the organic phase) is used as a de-emulsifier. The equilibration time is 45 min. The experimental results suggest that the extracted species is always TiOA2 (o), though the composition of the reacting aqueous Ti(IV) species may vary depending on the concentration levels of Ti(IV), pH, HA and. The equilibrium constant (Kex) at 303 K is measured to be 101.117and 10−1.243for the reaction of monomeric, non-sulfated, mono, and non-hydrolyzed TiO2+, respectively. The effects of heptan-1-ol, temperature, loading, and diluent type have been reported. Stripping can be done effectively by a solution of 1 mol/dm3H2SO4containing 5%(v/v) of “100 volume” H2O2. The possibilities of separation of Ti(IV) from Cu(II), Zn(II), Fe(III), Co(II), and Ni(II) have been predicted. It is proved to be an effective extractant for Ti(IV)/Fe(III) separation from sulphate medium at pH ∼ 1. [ABSTRACT FROM PUBLISHER]

Extraction and separation of divalent Mn and Zn ions from acidic sulfate solutions containing 0.05 M of each metal ion have been carried out using 0.04 M Na-CYANEX 272 in kerosene. The influences of the following parameters were studied: shaking time, equilibrium pH, extractant concentration, diluents type, and temperature. The extraction percentage of both metal ions increased with increasing equilibrium pH in the range 2.0–4.0 and 2.75–6.0 for Zn(II) and Mn(II), respectively. The separation factor, S(Zn/Mn), increases with the increase in pH to reach a maximum value of about 24 × 103at pH 4.0. Extraction of both metal ions increased with increasing extractant concentration. Aliphatic diluents were preferred compared to aromatic diluents. The thermodynamic parameters (ΔH, ΔS, and ΔG) for Mn(II) and Zn(II) were calculated. The extraction mechanism of both metals by Na-CYANEX 272, stripping from loaded extractant and recycling of extractant used in the extraction process were also investigated. [ABSTRACT FROM PUBLISHER]

As one kind of the most important intermediate materials in rare earth (RE) industry, RE sulfates have been considered difficult to be extracted and separated directly by saponified extractants due to the dissolubility of RE double sulfate ofcation. By introducing a barrier agent such as Mg2+ion in the present work, we proposed and developed a process to extract RE cations in sulfate medium with saponified HEH(EHP). Further, a selection criterion of the barrier agent was discussed. The results have revealed that the natural distribution of the univalent ion, RE3+and Mg2+ions, as determined by their extraction sequence in the cascade, hinders the contact betweencation and RE ions, and thereby RE double sulfate precipitate does not form during the extraction. Consequently, the study can provide us a strong possibility for extracting and even separating RE using saponified extractants directly from sulfate solution in no need of any transformation of the RE salts employed. [ABSTRACT FROM PUBLISHER]

The purpose of this study is to investigate the impact of precipitant additives, i.e., calcium hydroxide (Ca(OH)2), calcium carbonate (CaCO3) and recycled sludge (RS), on the settling and compacting performance of sludge formed in the process of heavy metal wastewater treatment using bio-polymer ferric sulfate (BPFS). The results show that CaCO3is the most suitable additive since heavy metal removal, sludge settling performance, and compacting performance is improved by 20%, 83.3%, 23.5%, respectively. In addition, scanning electron microscopy and X-ray diffraction were measured for contrasting the sludge morphology and crystallinity. The results suggest that CaCO3acted as seeding material produces the largest flocs. Moreover, the flocculation theory combined with zeta potential measurement was used to explain the sludge formation mechanism, which is proposed as charge neutralization by BPFS, sweep flocculation by amorphous precipitate, and bridging flocculation by polyacrylamide (PAM) in sequence. The improvement of sludge properties by adding CaCO3benefits from the enhancement of sweep flocculation. In summary, the interaction mechanism between precipitant additives and sludge performance is well understood, thus providing useful information about adding precipitant additives to improve both the sludge settling properties and the quality of the treated water during the heavy metal wastewater treatment. [ABSTRACT FROM PUBLISHER]

A new macroporous poly(styrene-co-divinylbenzene)-based monolithic stationary phase for capillary electrochromatography (CEC) was prepared by using emulsion templating technique without using a charge bearing comonomer. In this preparation, styrene and divinylbenzene in the continuous phase of a high internal phase emulsion were copolymerized in the presence of 90 vol.% of internal aqueous phase. The resulting monolithic column had a well-defined interconnected open-cell structure with micro size spherical voids. It indicated an adequate electroosmotic flow (EOF) without any charge bearing monomer due to the presence of ionizable sulfate end groups formed by the initiator used in the polymerization. The effect of mobile phase composition (pH and acetonitrile content) and voltage on EOF mobility were examined. Furthermore, it was successfully used for the separation of alkylbenzenes with theoretical plate numbers up to 142 000 plates/m. [ABSTRACT FROM AUTHOR]

Hydrophobic pyridyl ketoximes: 1-(2-pyridyl)tridecan-1-one oxime, 1-(3-pyridyl)tridecan-1-one oxime and 1-(4-pyridyl)tridecan-1-one oxime have been synthesized and investigated as extractants of copper(II) ions. Removal of metal ions was conducted from chloride, sulphate, and sulphate/chloride solutions. The influence of pH of aqueous solutions, copper(II), chloride, and sulphate ions and ligand concentration for extraction process were studied. Copper(II) extraction by hydrophobic 2-, 3-, and 4-pyridyl ketoximes from sulphate solutions is not possible. However, addition of chloride ions to initial sulphate media enables metal removal. The oxime of 1-(2-pyridyl)tridecane-1-one was determined as the strongest extractant of the tested oximes, but metal stripping was impossible. For the rest of the studied extractants the stripping process could be done using water or diluted mineral acid. [ABSTRACT FROM PUBLISHER]

Separation of nickel(II) and cadmium(II) ions from sulphate solution has been studied. The solutions of Ni(II) and Cd(II) have been treated with different exchange resins: Lewatit OC-1026, Lewatit TP-207, and Lewatit MonoPlus SP 112. Data obtained from the ion-exchange process was compared with data from the supported liquid membrane experiment. It was shown that the use of the supported liquid membrane process enables separation of investigated ions. In this process the highest recovery factor was obtained. The best separation of metal ions was obtained for the ion-exchange process with Lewatit OC 1026. [ABSTRACT FROM PUBLISHER]

Laboratory electrokinetic (EK) tests were conducted for the restoration of saline soil which contained mainly Na+, Cl− and ions. The effect of anode materials on salt removal was investigated by comparing various anodes such as dimensionally-stable anode, Pt, Si/BDD (boron-doped diamond), and Fe electrode. In all tests Na+ and Cl− were easily removed from the soil (>97%). Fe tests showed higher reduction of concentration and resulted in higher electrical conductivity reduction (∼90%) than the other anode tests. The results demonstrated that the EK process can reduce soil salinity effectively and the Fe anode is more suitable for restoration of sulfate-rich saline soil than other insoluble anodes. [ABSTRACT FROM PUBLISHER]

Low density microspheres were used to float flocs formed from the coagulation of natural organic matter (NOM) using ferric sulphate coagulant. Microspheres were visually observed to be incorporated into the floc structure during the coagulation phase. In comparison with conventional flotation with air bubbles, the residual turbidity after flotation using the microspheres was very favorable and did not impact on overall NOM removal. Spheres of the lowest density and largest particle size gave the most rapid floc clearance, but the residual turbidity after 10 minutes flotation was similar for all of the spheres investigated. The results of this work have shown that floating microspheres offer an effective, energy efficient alternative to conventional dissolved air flotation for the removal of flocs containing high concentrations of NOM. [ABSTRACT FROM AUTHOR]

A model approach is presented here to obtain sorption isotherms that are connected with a low cost breakthrough analysis for dry desulphurization of flue gas in a fluidized bed reactor. Experiments were conducted at different temperatures (600-900°C) providing constant feedstock concentration (0.6% SO2). The fluidizing gas entered the bed through a distributor and fluidized the single charge of 15 g sorbent. The space velocity ranged from 3100 to 5700 h-1. Each run was terminated when the steady state was reached. Sulfate layer thickness was calculated from conversion ratio and the structural parameter. Inserting this value and the particle size parameter into the mass transfer equation then extracted the process parameters. Equilibrium relationships involving these parameters were compared with different isotherms. The agreement between the experimental and predicted values of the sorption isotherms validated the model. The latter may be successfully used to design reactors for e.g., sulfating or desulphurization. [ABSTRACT FROM AUTHOR]

Removal of low concentration of fluoride (2 mg F-/L) in the presence of chloride and sulfate ions from aqueous solution by electrodialysis was studied. The equivalent ratios of sulfate and/or chloride were investigated as co-existing ions on fluoride removal from aqueous solution. The separation performance was evaluated in terms of mass transfer and energy consumption. It was obtained that the separation performance increased when the equivalent ratios of chloride to fluoride and sulfate to fluoride were increased. After 13 min of operation time, 63% of fluoride was removed from the solution when a binary mixture of F- : Cl- (1 : 25) was employed. In the case of a binary mixture of F- : [image omitted] (1 : 25), removal of fluoride was 93% in 16 min. For a ternary mixture of F- : Cl- : [image omitted] (1 : 25 : 25), fluoride was separated from the mixture with a 96% of removal in 20 min. [ABSTRACT FROM AUTHOR]

Extraction kinetics of thorium(IV) with primary amine N1923 in sulfate media has been investigated by a constant interfacial cell with laminar flow. Studies of interfacial tension and effects of the stirring rate, temperature, and specific interfacial area on mass transfer rate show that the most probable reaction zone takes place at the liquid-liquid interface. According to the experimental data correlated as a function of the concentration of the relevant species involved in the extraction reaction, the rate equation of extracting thorium has been obtained as follows: [image omitted] The kinetic mechanism of the extraction process is proposed taking an interfacial chemical reaction as the rate-determining step of the overall reactions. [ABSTRACT FROM AUTHOR]

Polyelectrolyte-enhanced ultrafiltration (PEUF) involves addition of a polyelectrolyte of opposite charge to that of the multivalent ions to be removed from the contaminated water. In this study, a water-soluble polyelectrolyte, poly(diallyldimethyl ammonium chloride) or QUAT is added to the aqueous solutions containing divalent anions chromate or sulfate. Removal of monovalent anion nitrate is also studied to probe the effect of valence. The water is then passed through an ultrafiltration membrane with pore size small enough to reject the polyelectrolyte with the bound target ions. The rejection of anions increases with increasing concentration ratio of QUAT to anion. A high QUAT concentration in the retentate decreases relative flux due to accumulation of polyelectrolyte near the membrane surface (hydrodynamic boundary layer). Rejections of chromate and sulfate are similar and >98% at reasonable operating conditions. Rejection of nitrate is substantially below that of the divalent anions, but can be as high as 97% under feasible operating conditions. The gel concentration (where flux approaches zero) of the QUAT varied from 5.1 to 8.1 wt%. [ABSTRACT FROM AUTHOR]

A hydrometallurgical treatment was applied to the Hajar Mine Copper Concentrate (HMCC), Morocco, containing approx. 28.1% copper (the major copper mineral phase is chalcopyrite, CuFeS2), approx. 26.1% iron, approx. 5.8% zinc, approx. 1.9% lead, approx. 33.7% sulphur, and small amounts of silver (269 g/t) and nickel (219 g/t). Three acid media were used: ferric sulphate in sulfuric acid, ferric sulphate in hexafluorosilicic acid, and a hexafluorosilicic acid–nitric acid mixture. The results show that when a ferric sulphate reagent is used, in H2SO4, as well as in H2SiF6 media, dissolution of copper and iron do not exceed 30%, because of the formation of a passivation layer on chalcopyrite particles, whereas zinc is dissolved at about 90%. The final solid leachate residue represents 75% by weight of the initial solid and remains rich in copper (approx. 28%) and iron (approx. 25%). However, under strong acid and oxidizing conditions, in the hexafluorosilicic acid–nitric acid mixture, the dissolution of copper is more efficient, although it is nonselective, (92% Cu, 89% Fe, 98% Zn). The solid leachate residue represents only 40% by weight of the original sample, and assays 5.9% Cu, 7.3% Fe, 0.2% Zn, 4.1% Pb, and 56.4% Stotal. Mineralogical characterizations of the leachate solid residues show the formation of both elemental sulphur and a Cu1-xFe1-yS2-z layer on the surface of the nondissolved chalcopyrite. [ABSTRACT FROM AUTHOR]