Enhanced adsorption behavior of Nd(III) onto D113-III resin from aqueous solution

An enhanced adsorption and desorption procedure of Nd(III) onto D113-III resin were prepared with various chemical methods.Batch studies were carried out with various pH,contact time,temperature and initial concentrations,and then column studies were conducted.The results showed that the optimal adsorption condition was at pH value of 6.90.The process was fast initially and arrived equilibriumwithin 60 h.The resin exhibited a high Nd(III) uptake as 232.56 mg/g at 298 K.The adsorption data fitted well with p...     

Evaluation of D113 cation exchange resin for the removal of Eu(III) from aqueous solution

Batch adsorption experiments were conducted for the adsorption of Eu(III) ions from aqueous solution by D113 resin. The results indicated that D113 resin could adsorb Eu(III) ion effectively from aqueous solution. The adsorption was strongly dependent on pH of the medium with enhanced adsorption as the pH turned from 3.50 to 7.00 and the optimal adsorption condition was in HAc-NaAc medium with pH value of 6.50. The maximum uptake capacity of Eu(III) ions was 290.9 mg/g D113 at 298 K, at an initial pH value of 6.50. The overall adsorption process was best described by Lagergren-first-order kinetics. When Freundlich and Langmuir isotherms were tested, the latter had a better fit with the experimental data. The thermodynamic parameters such as free energy (?G) which were all negative, indicated that the adsorption of Eu(III) ions onto D113 resin was spontaneous and the positive value of enthalpy (?H) showed that the adsorption was endothermic in nature. Thomas model was applied to experimental column data to determine the characteristic parameters of column useful for process design. Furthermore, Eu(III) could be eluted by using 3.0 mol/L HCl solution and the D113 resin could be regenerated and reused.     

Adsorption behavior of Cd(II) from aqueous solutions onto gel-type weak acid resin

The adsorption and desorption behaviors of Cd(II) on gel-type weak acid resin (GTWAR) have been investigated. The influence of operational conditions such as contact time, initial concentration of Cd(II), initial pH of solution and temperature on the adsorption of Cd(II) has also been examined. The results show that the optimal adsorption condition of GTWAR for Cd(II) is achieved at pH = 5.95 in HAc–NaAc medium. The maximum uptake capacity of Cd(II) is 282 mg/g GTWAR at 298 K. The adsorption of Cd(II) follows the Langmuir isotherm and Freundlich isotherm, and the correlation coefficients have been evaluated. Even kinetics on the adsorption of Cd(II) has been studied. The apparent activation energy E_a and adsorption rate constant k₂₉₈ values are 2.95 kJ/mol and 3.02 × 10^− 5 s^− 1, respectively. The calculation data of thermodynamic parameters which ΔS value of 110 J/(mol K) and ΔH value of 13.1 kJ/mol indicate the endothermic nature of the adsorption process. Whilst, a decrease of Gibb's free energy (ΔG) with increasing temperature indicates the spontaneous nature of the adsorption process. Finally, Cd(II) can be eluted by using 0.5 mol/L HCl solution and the gel-type weak acid resin can be regenerated and reused. The sample was described by IR spectroscopy and scanning electron micrographs (SEM).     

Adsorption and desorption properties of D151 resin for Ce(III)

The present research is aimed at the development of D151 resin as an adsorbent that it can be used in the adsorption of Ce(III) ions. The adsorption and desorption behaviors of Ce(III) on D151 resin have been investigated by chemistry analysis. The influence of operational conditions such as contact time, initial concentration of Ce(III), initial pH of solution and temperature on the adsorption of Ce(III) had also been examined. The results show that the optimal adsorption condition of D151 for Ce(III) was achieved at pH=6.50 in HAc-NaAc medium. The maximum uptake capacity of Ce(III) was 392 mg/g resin at 298 K. The adsorption of Ce(III) followed both the Langmuir isotherm and Freundlich isotherm, and the correlation coefficients had been evaluated. Even kinetics on the adsorption of Ce(III) had been studied. The adsorption rate constant k_{298 K} valued was 1.3×10^?5 s^?1. The calculation data of thermodynamic parameters which ΔS⁰ value of 91.34 and ΔH⁰ value of 7.07 kJ/mol indicate the endothermic nature of the adsorption process. While, a decrease of Gibb's free energy (ΔG⁰) with increasing temperature indicated the spontaneous nature of the adsorption process. Finally, Ce(III) could be eluted by using 0.5 mol/L HCl solution and the elution percentage was as high as 100%. Adsorption mechanism was also proposed for the adsorption of Ce(III) ions onto D151 resin using infrared spectroscopy technique.     

Adsorption of arsenate and arsenite from aqueous solutions by cerium-loaded cation exchange resin

The removal of arsenic from water and wastewater is obligatory.Resin is one of the most effective adsorbents for the removal of arsenic.In order to improve the adsorption capacity of resin,a new cerium-loaded cation exchange resin arsenic adsorbent was prepared by impregnating cerium into the cation exchange resin.Batch adsorption experiments under various conditions,such as time,temperature,pH and with coexisting ions were carried out to evaluate the adsorption characteristics of cerium-loaded resin in the removal of As(Ⅴ)and As(Ⅲ) from aqueous solutions.The results showed that the adsorption kinetics of As(Ⅴ)and As(Ⅲ)obeyed a pseudo second-order kinetic model and the adsorption rate constants were 0.3159 and 0.5215 g·mg-1 ·min-1 ,respectively.The adsorption of As(Ⅴ)followed the Freundlich adsorption isotherm model and the adsorption isotherm data for As(Ⅲ)fitted well to the Langmuir equation model.The adsorption capacities were 1.0278 mg/g for As(Ⅴ)and 2.5297 mg/g for As(Ⅲ).Both the adsorption of As(Ⅴ)and As(Ⅲ)were found to be pH sensitive and the optimum pH was found to be 5-6.Except for the phosphate ion,the coexisting anionics,such as nitrate,chlorate,sulphate and carbonate,showed no remarkable effect on As(Ⅴ)and As(Ⅲ)adsorption.The desorption and regeneration study showed that the adsorption capacity of Ce-loaded resin for As(Ⅴ)and As(Ⅲ)could be restored to 97.80%and 69.61%,respectively,using 0.5 mol/L sodium hydroxide solution.     

Separation of praseodymium(III) from aqueous solutions by nanofiltration

Abstract

The increased demand for rare earth elements in commercial products is increasing their production, which in turn increases public exposure to rare earth elements. The objective of the present work is to study the separation of praseodymium from aqueous solutions by a commercial nanofiltration membrane (NF-300) at various operating conditions. The permeate and feed samples were analysed with inductively coupled plasma atomic emission spectrometry (ICPAES) to find praseodymium [Pr(III)] concentration. The results indicated that the separation of Pr(III) ions increased with increase in applied pressure (2–10 bar) and cross flowrate (4–16 L min^?1); and decreased with increase in feed concentration (10 mg L^?1 PrCl₃ – 100 mg L^?1 PrCl₃). The highest observed separation of the Pr(III) was found to be 89·07 and 84·20% for an initial feed concentration of 10 and 100 mg L^?1 PrCl₃ respectively. It was also observed that separation of Pr(III) increases to 99·28 and 99·30% in complexation step by using ethylene diamine tetra aceticacid (EDTA) and diethylene triamine penta aceticacid (DTPA) respectively, as the chelating agent has generally influenced by pH (2 –10).

La demande accrue d’éléments de terres rares dans les produits commerciaux augmente leur production, ce qui, à son tour, augmente l’exposition du public aux éléments de terres rares. Le but de ce travail est d’étudier la séparation du praséodyme à partir de solutions aqueuses au moyen d’une membrane commerciale de nanofiltration (NF-300) sous diverses conditions d’utilisation. On a analysé les échantillons de perméat et d’apport au moyen de la spectroscopie d’émission atomique avec plasma induit par haute fréquence (ICPAES) afin de déterminer la concentration du praséodyme [Pr(111)]. Les résultats indiquaient que la séparation d’ions de Pr(111) augmentait avec une augmentation de la pression appliquée (2–10 bar) et de la vitesse de l’écoulement transversal (4–16 L min^?1) et diminuait avec une augmentation de la concentration de l’apport (10 mg L^?1 PrCl₃ – 100 mg L^?1 PrCl₃). On a trouvé que la valeur la plus élevée de séparation observée pour le Pr(111) était de 89·07 ou de 84·20% pour une concentration initiale de l’apport de 10 ou de 100 mg L^?1 de PrCl₃, respectivement. On a également observé que la séparation du Pr(111) augmentait jusqu’à 99·28 ou 99·30% dans une étape de complexation en utilisant de l’acide éthylènediaminetétracétique (EDTA) ou de l’acide diéthylènetriamino-pentaacétique (DTPA), respectivement, comme agent chélateur, influencé généralement par le pH (2–10).     

The extraction of iron(III) from aqueous sulphate solutions by primene sulphate

A study of the extraction of iron(III) from aqueous sulphate media by the primary amine Primene 81R at 50°C has been made. The compound extracted from the organic phase with Primene 81R sulphate in kerosene has been isolated and recrystallized from a methanol-acetone mixture and has been shown to have the stoichiometric formula 3(RNH₃)₂SO₄·(Fe(OH)SO₄)₂ represents the alkyl groups associated with the amine. It has been shown that the extraction of iron(III) occurs by an adduct formation reaction between primary amine sulphate molecules and the species IFe(OH)SO₄I₂ from the aqueous phase. On the basis of the experimental data and spectral studies a dimeric structure is suggested for the extracted complex.     

The coprecipitation behavior of Co(II) and Ni(II) with Fe(III), Cr(III) and Al(III) from aqueous ammoniacal solutions

The coprecipitation of cobalt(II) and nickel(II) with iron(III), chromium(III) and aluminum(III) from ammoniacal solutions has been investigated. The coprecipitation behavior was found to be very sensitive to the solution pH and total ammonia concentration. Co(II) and Ni(II) can be precipitated from low ammonia concentration solutions but are readily redissolved at higher ammonia concentrations. The coprecipitate of divalent and trivalent species was found to contain very large amounts of the divalent metals (up to a mole ratio M M(II)/M(III) of 2.5) when aluminum was the trivalent species, whereas with iron(III) or chromium(III), the ratio was only 0.5.     

Reductive stripping of Fe(III)-loaded D2EHPA with the aqueous solutions containing sulfur dioxide

The stripping of Fe(III)-loaded D2EHPA, which is known to be difficult, was studied in the presence of SO₂. The stripping reaction of Fe(III) was greatly accelerated by the presence of SO₂, generating Fe(II) as a stripped species. In the presence of SO₂, the stripping of Fe(III) was favorable with all acids studied, including HC1, HC1O₄, and H₂SO₄, and even with water. Among various factors, the partial pressure of SO₂ was found to be the most important factor in controlling the rate of stripping as well as the rate of reduction of stripped Fe(III) in the aqueous phase. The removal of SO₂ dissolved in an organic phase was easily done by washing with aqueous H₂O₂ solution.     

The extraction of iron(III) from aqueous acid solutions by di(2-ethylhexyl)phosphoric acid

The extraction of iron(III) from aqueous solutions containing sulphuric, hydrochloric and nitric acids by di(2-ethylhexyl)phosphoric acid (DEHPA) in kerosene has been investigated under different conditions. As a result, it is found that although extraction is dominated by an ion-exchange reaction, the rate of iron(III) extraction from sulphuric acid solutions to reach equilibrium is relatively slow in comparison with that from hydrochloric or nitric acid solutions. In the extraction from aqueous solutions containing hydrochloric or nitric acid, however, the DEHPA combines with iron(III) according to the solvating reaction at higher aqueous acidity. From studies on the rate of the extraction from sulphuric acid solutions, examined under non-equilibrium, it is confirmed that dependencies of extraction rate on hydrogen ion and DEHPA concentrations are in the first and inverse first orders, respectively. The hydrolyzed species is considered to interpret the extraction mechanism in this system.     

Effect of pH on sorption for RE（Ⅲ） and sorption behaviors of Sm（Ⅲ） by D152 resin

The pH dependent sorption of rare earth ions （La（Ⅲ）, Ce（Ⅲ）, Pr（Ⅲ）, Nd（Ⅲ）, Y（Ⅲ）, Sm（Ⅲ）, Eu（Ⅲ）, Gd（Ⅲ）, Tb（Ⅲ）, Dy（Ⅲ）, Ho（Ⅲ）, Er（Ⅲ）, Lu（Ⅲ）, and Yb（Ⅲ）） from HAC-NaAC buffer solution at 298 K by D152 resin containing -COOH function groups were presented. The sorption behaviors of D152 resin for Sm（Ⅲ） were discussed as an example. The effects of operational conditions such as pH, temperature, and contact time were studied. The statically saturated sorption capacity was 510 mg/g resin at pH 6.70 in HAc-NaAc medium at 298 K. The sorption behaviors obeyed the Freundlich isotherm. The capacity value for column study was obtained by graphical integration as 495 mg/g resin. Thomas model was applied to experimental data to predict the breakthrough curve and to determine the characteristic parameters of the column useful for process design.     

改性油页岩残渣对苯胺的吸附性能研究

为探讨油页岩矿山开采加工过程中产生的油页岩残渣环保利用的新途径,在油页岩残渣改性的基础上,研究了其对有机污染物苯胺的吸附作用。利用NaOH对油页岩残渣进行改性,设计正交试验优化了改性油页岩残渣吸附苯胺的最佳条件。其试验结果表明:在改性油页岩残渣粒径为0.01 mm、振荡速度为100 r/min、改性油页岩残渣用量为2 g/100 mL、温度10℃、pH7、吸附时间为40 min的最优化条件下,对初始质量浓度为20 mg/L苯胺的去除率可达83.92%。同时,绘制了改性油页岩残渣吸附苯胺的吸附等温性,其吸附过程与Langmuir和Freundlich吸附等温线拟合。     

Recovery of Al(III) and Fe(III) from mixed chloride solutions containing platinum(IV)

The sorption of Fe(III), Al(III) and Pt(IV) from the individual and mixed chloride solution was investigated by using PC88A resin. With the increase of HCl concentration to 5 M, the distribution coefficient of Fe decreased slowly, while that of Al decreased rapidly and the distribution coefficient of Pt was nearly zero in our experimental range. Batch experiments showed that it was possible to extract both Fe and Al simultaneously by adjusting HCl and PC88A resin concentrations. However, continuous extraction chromatographic experiments indicated that simultaneous sorption of Al as well as Fe was difficult in our experimental range. Two extraction chromatographic steps would extract most of Fe and 90% of Al from the mixed solution, while Pt was not extracted. Extraction chromatography of the mixed chloride solution with PC88A resin was found to be fast and simple.     

Extraction of Fe(III) from hydrochloric acid solutions using Amberlite XAD-7 resin impregnated with trioctylphosphine oxide (Cyanex 921)

Ferric ions were efficiently removed from HCl solutions using Amberlite XAD-7 resin impregnated with trioctylphosphine oxide (Cyanex 921). Iron was removed under the form HFeCl₄ through direct binding on the resin or by extraction with Cyanex 921 involving a solvation mechanism. High concentrations of HCl and intermediary extractant loadings were required for maximum sorption efficiency and rationale use of the extractant. At intermediary extractant loading (in the range 300–450 mg Cyanex 921 g^− 1) the maximum sorption capacity increased with extractant loading. Maximum sorption capacity slightly increased with temperature, the reaction is endothermic and the enthalpy change was found close to − 30.8 kJ mol^− 1. Sorption isotherms were fitted with the Langmuir equation and maximum sorption capacity reached values as high as 20–22 mg Fe g^− 1 in 3 M HCl solutions. Despite the good fit of experimental data with the pseudo second-order rate equation, sorption kinetics was controlled by the resistance to intraparticle diffusion. The intraparticle diffusion coefficient (D_e) varying in the range 1.2 × 10^− 11–4.7 × 10^− 10 m² min^− 1 was found to increase with metal concentration and with temperature, while varying the extractant loading it reached a maximum at a loading close to 453 mg Cyanex 921 g^− 1. The desorption of Fe(III) can be achieved using 0.1 M solutions of nitric acid, sulfuric acid, sodium sulfate and even water, maintaining high efficiencies for sorption and desorption for at least 5 cycles.     

Extraction and separation of In(III), Ga(III) and Zn(II) from sulfate solution using extraction resin

The separation of In(III), Ga(III) and Zn(II) from sulfate solution has been studied using an extraction resin containing 2-ethylhexyl phosphoric acid mono(2-ethylhexyl) ester (P507 extraction resin). The effect of pH on the extraction of each metal was determined. Extraction isotherms were then constructed at selected pH. Results show that In(III) is first extracted from aqueous solutions at pH 2.0 using this resin while Ga(III) and Zn(II) are co-extracted at pH 3.0. Their separation can be carried out using HCl of different concentrations as eluants. The saturation adsorption capabilities of indium(III) and gallium(III) were evaluated as 47.2 and 31.0 mg/g or 0.41 and 0.44 mmol/g, respectively. The molar ratio of metal ion: P507 reagent on resin was about 1:3. Loaded resins can be regenerated, and the metals can be recovered selectively. Two fixed-bed columns arranged in-series were successfully used for the separation and recovery of these three metal ions from a multi-component solution.     

Solvent extraction-separation of La(III), Eu(III) and Er(III) ions from aqueous chloride medium using carbamoyl-carboxylic acid extractants

N,N-dibutyldiglycol amic acid(HLI) and N,N-dioctyldiglycol amic acid(HLII) were synthesized and characterized by conventional spectroscopic methods. These molecules were examined as extractants for extraction-separation of La(III), Eu(III) and Er(III), as representative ions of light, middle and heavy rare earths, from aqueous chloride solutions. The analysis of the extraction equilibria revealed that the extracted species of lanthanum and europium ions by both of the extractants had a 1:3 metal to ligand ratio. It was suggested that erbium ions were extracted into the organic phase via the formation of Er(LI or II)2Cl complexes. The effect of the organic diluents on the extraction-separation efficiency of the studied rare earths by HLI and HLII was investigated by comparing the results obtained in dichloromethane and carbon tetrachloride. Regardless to the diluent used, the order of selectivity presented by the investigated extractants was Er(III)Eu(III)La(III). It is noteworthy that, a significant enhancement in separation of the studied rare earths by the extractants was achieved in their competitive extraction experiments with respect to that obtained in single component extraction experiments. Applicability of the extractants for the removal of rare earth ions from spent Ni-MH batteries was tested by removal of La(III), Eu(III) and Er(III) ions from simulated leach solution of such batteries.     

Adsorption of rhenium(VII) on 4-amino-1,2,4-triazole resin

The adsorption properties of 4-amino-1,2,4-triazole resin (4-ATR) for Re(VII) were investigated by static and dynamic adsorption–desorption measurements with ultraviolet–visible spectroscopy. The influence of conditions such as temperature, initial solution pH and contact time on the adsorption curve was studied. It was found that the 4-amino-1,2,4-triazole resin was suitable for adsorption of Re(VII). The saturated adsorption capacity was 354 mg·g^− 1resin at pH 2.6 in HAc–NaAc medium at 298 K. The adsorption rate constant was k₂₉₈ = 8.2 × 10^− 5 s^− 1. The adsorption behavior of 4-ATR for Re(VII) obeyed the Freundlich empirical equation; whilst changes in adsorption with temperature gave an enthalpy change ΔH  = − 11.8 kJ·mol^− 1. The molar ratio of the functional group of 4-ATR to Re(VII) was about 2:1. Re(VII) adsorbed on 4-ATR was eluted by 1.0 ~ 5.0 mol·L^− 1 HCl with 100% quantitative elution in 4.0 mol·L^− 1 HCl solution. The resin can be regenerated and reused without apparent decrease in adsorption capacity.     

The adsorption extraction of nickel(II) ions from aqueous solutions

Processes of the sorption of nickel(II) ions from aqueous solutions on carbon adsorbents synthesized based on fossil coals are investigated. The maximal adsorption is observed in a neutral medium. Adsorption isotherms are obtained under static conditions in various temperature modes. It is shown that they are described satisfactorily by the Langmuir isotherm. The decrease in the value of adsorption as the temperature increases indicates that the process is exothermic. The kinetics of the process is investigated and thermodynamic parameters of adsorption are determined.     

Study of erbium (III) doped titanium dioxide nanoparticles by photoacoustic spectroscopy

Nanocrystalline titania as photocatalyst has attracted considerable attention for its potential use in environmental cleaning. Recently, lanthanide ions doped titania samples have been shown to increase the photocatalytic efficiency of selected reactions. In this work, TiO₂ nanoparticles doped with Er³⁺ were prepared via an ultrasonic assisted sol-gel method. The optical properties of the samples were determined by photoacoustic (PA) spectroscopy. It was found that the absorption edge shifted to lower wavelength when the particle size fell into nanometer range, which is the evidence of a quantum size effect. The nature of ligand bonding to Er³⁺ and the structural properties were investigated with the PA absorptions of the f-f transitions of Er³⁺, which are sensitive to the local environment. The results showed that TiO₂ gel heated at 70 °C still contained abundant trapped water and ethanol, and the environment around Er³⁺ was similar to the one in the aqueous ion. The “degree of covalency” for Er³⁺ bonding increased continuously during the gel-to-anatase transition. For the sample calcined at 1100 °C, however, the f-f transitions of Er³⁺ showed blue shifts and the intensity of the hypersensitive transition decreased, indicating an increase of ionicity in the Er³⁺ bonding. This can be attributed to the segregation of Er³⁺ ions to the external surface, forming Er₂Ti₂O₇ during the anatase-to-rutile transition, which was confirmed with XRD and TEM measurements.