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1.
Kinetic analysis of removal of three rare earth elements metals, Ce3+, Sm3+, and Yb3+ ions from aqueous solutions in a continuous flow fixed bed reactor using Dowex 50W-X8 ion-exchange resin was conducted. The performance of the fixed bed sorption was evaluated using the concept of the sorption breakthrough process. Parameters characteristic of a fixed bed sorption such as breakthrough times, saturation times, critical reactor lengths, and lengths of mass transfer zone were inferred from the metal ion concentration breakthrough curves. The sorption capacity of Dowex 50W-X8 ion-exchange resin for Ce3+, Sm3+, and Yb3+ are 191, 252, and 294 mg/g, respectively. The sorption kinetics were evaluated using a zero-order, first-order and second-order reaction models. The kinetics of the sorption process follows a zero-order model which has not been reported before. The rate constants of sorption using the zero-order kinetic model are obtained. Two different analysis were conducted to identify whether the diffusion is intraparticle or film diffusion. Both analysis confirms that the film diffusion is the controlling mechanism in reactor bed.  相似文献   

2.
The sorption behavior of iron onto two anion exchange resins from simulated aluminum chloride leach liquors was studied. Bench-scale sorption isotherm experiments were performed at room temperature. The initial chloride concentrations of the simulated leach liquors ranged from 1 M to 6 M. Iron loading for the Dowex SBR and Dowex MWA-1 resins increased with increasing chloride concentrations. Maximum capacities observed for both resins were approximately 0.95 meq Fe/g dry resin at an initial chloride concentration of 6 M. The Dowex SBR resin sorbed noticeably greater amounts of iron than the MWA-1 resin at initial chloride concentrations of 4 and 5 M. Computer programs were written to predict the equilibrium distribution of species in various aqueous electrolytes. Correlation of computer results with some published experimental data indicated good qualitative correlations. However, strict quantitative conclusions may be suspect due to an inability to predict activity coefficients accurately at the high ionic strengths of this work. Comparison of computer program predictions and sorption isotherm results indicate that the species FeCl3(aq) may be involved in the sorption of iron from the simulated leach liquors.  相似文献   

3.
In this study, strontium adsorption from sulfuric acid solution by different Dowex 50W-X ion exchange resins was investigated. Among these resins, Dowex 50W-X8 resin showed the maximum sorption of strontium from the aqueous solutions. The effect of pH, contact time, mass of resin, temperature, and concentration of interfeting ions on strontium adsorption were evaluated to determine the optimum conditions of strontium sorption process. The kinetic models of sorption were analyzed using pseudo-first and pseudo-second order models. The results indicated that the pseudo-second order kinetic model was more appropriate than the other one. Moreover, the data obtained in this study were fitted into several sorption isotherm models and it was found that the Langmuir sorption isotherm shows the best fitting to the experimental data.  相似文献   

4.
Gold extraction technology based on anion exchange resins with mixed basicity, commonly used in former soviet countries, includes a complicated and expensive process of resin regeneration and gold stripping by thiocarbamide solution. Satisfactory sorption properties of weak base anion exchange resin at pH 6–8 and low cost of metal stripping by sodium hydroxide solution have aroused considerable interest in these resins as perspective means of gold extraction from cyanide pulps on a large scale. However, the possibility of industrial use of weak base anion exchange resins is hindered by their extremely low sorption activity at pH 10.5 and the formation and release of HCN in the pulp at pH 6–8.

The development of weak-based anion exchange resins which permits efficient gold sorption at pH 10.5 has already been described in literature. A special procedure for treating cyanide pulps has been devised in ?Irgiredmet”. It allows a sigificant rise of gold distribution coefficient between anion exchange resins and liquid phase.

Studies including counter-current tests of gold sorption by anion exchange resins of mixed and weak basicity from cyanide solutions and pulps treated accordingly were carried out. It was found that the gold capacity of mixed base resins has risen by 2–3 times, and the resin flowrate and reagent consumption during its regeneration and gold stripping by thiocarbamide solution have decreased proportionally. After special treatment the gold capacity of weak base resins in solutions and pulps is 3–6 times greater than in nontreated solutions and pulps, which indicated that the sorption capacity of resins is used to the full extent. Introduction of special treatment of cyanide pulp into existing technology makes possible an efficient industrial use of commercially available weak base anion exchange resins for gold recovery.  相似文献   

5.
树脂富集铼的研究   总被引:1,自引:0,他引:1  
用201×7强碱性凝胶型离子交换树脂对钼精矿焙烧烟尘浸出液中的铼进行分离富集工艺条件进行研究。通过对溶液中主要金属离子存在状态的分析,选择用201×7树脂对溶液中铼进行离子交换吸附,对该树脂在实验溶液中的有关吸附交换的表观吸附容量、吸附溶液pH等进行了实验研究,另外选择出了对负载树脂上铼进行有效解吸的解吸剂,并进行了动态解吸。实验结果表明:烟尘浸出液经氧化预处理后,用201×7树脂在常温,pH=9.0时可以对浸出液中的铼有效富集,树脂对铼的表观饱和吸附容量为92 mg/g;采用1 mol/L的硝酸溶液可以对负载树脂上的铼进行有效的解吸。  相似文献   

6.
A detailed study has been carried out to investigate the possibility of recovering vanadium by resin ion exchange from acid sulfate solutions containing 10 mg/l vanadium. In particular the recovery of vanadium by an anion exchange resin, Dowex 21K, has been investigated. Batch loading tests have been carried out to elucidate the role of Eh and pH on vanadium loading. An Eh-pH diagram has been constructed to determine the most stable vanadium species in solution at different Eh and pH conditions, and this information has been used to explain and predict the loading of vanadium onto the anion exchange resin. Kinetic data have been obtained for the loading of vanadium at different pH values. A film diffusion model has been found to fit the experimental data gathered at pH 4.0, while a particle diffusion model seems to offer a better fit to the experimental data at pH 2.0.  相似文献   

7.
The influence of tin (II) chloride additives on sorption of Rh(III) on the Purolite S920 ion exchange resin with isothiouronium groups, the Purolite S985 weak base anion exchange resin, and the Purolite A500 strong base anion exchange resin is investigated. It is established that the introduction of SnCl2 leads to a substantial increase in selectivity of all tested ion exchange resins to Rh(III) and in the sorption rate of Rh(III) on S985 and S920 ion exchange resins. The optimal dosage of SnCl2 (0.01 mol/L) at which the distribution coefficients of Rh(III) during sorption for all tested ion exchange resins reach maximal values is determined. It is shown that almost quantitative recovery of Rh(III) is attained when passing the multicomponent chloride solution of the composition (g/L) 0.2 Rh(III), 72.9 HCl, 53.5 NH4Cl, 2.7 Al(III), 1.23 Fe(III) and 5.9 Sn(IV) with the SnCl2 additive through the Purolite S920 ion exchange resin with isothiouronium groups. Desorption of Rh(III) from the Purolite S920 saturated ionite with the acidified thiourea solution is incomplete, no greater than 60%.  相似文献   

8.
《Hydrometallurgy》2007,87(3-4):221-229
Imidazolium nitrate functional groups (Im–NO3) were anchored onto a polystyrene–divinylbenzene resin matrix, and investigated for the extraction of palladium (II) from nitric acid medium. The rate of extraction and distribution coefficient, Kd, mL/g, of palladium (II) were measured as a function of extent of functionalization, and concentrations of nitric acid, sodium nitrate and palladium nitrate. Kd values of palladium (II) show a maximum in 3.0 M–4.0 M nitric acid. Slope analysis of the distribution data obtained at various aqueous phase nitrate concentrations and resin phase exchanging capacity suggest the involvement of anion exchange mechanism for the extraction of palladium (II) from nitric acid medium. The ion exchange isotherm was fitted using Langmuir adsorption model and the apparent ion exchange capacity (b = 88 mg/g) was determined. The performance of the resin under dynamic conditions was evaluated by following a breakthrough curve and the data was fitted using Thomas model.  相似文献   

9.
为了验证离子交换树脂在电解金属锰废水行业中的应用效果,通过静态吸附实验、中试动态实验的方法,研究了不同类型离子交换树脂对锰离子的吸附性能及回收特性。结果表明,离子交换树脂对锰离子有一定的交换吸附能力,且同类树脂对各二价金属离子选择性无明显区别,其中各树脂对二价金属离子的吸附能力:D113〈732〈D851。经过一次再生后,离子交换树脂交换吸附能力下降,之后进行多次再生后,其交换吸附能力基本趋于稳定,钙离子对离子交换树脂的再生一吸附有较大负面影响。洗脱液中锰离子浓度最高可达20000mg/L以上。  相似文献   

10.
In this study, the influence of solution pH and ionic strength on sorption of chromate by surfactant-modified zeolite was tested. The sorption of chromate followed a Langmuir isotherm under different pH and ionic strength conditions. However, as the solution pH and ionic strength increased, the Langmuir sorption coefficient of chromate decreased systematically, reflecting an increased competition of background electrolyte anions against chromate for sorption sites. The chromate sorption maximum also decreased slightly as the solution pH and ionic strength increased. The stoichiometric relationship between chromate sorption and counterion desorption further indicated that chromate sorption on surfactant-modified zeolite surfaces was mainly due to surface anion exchange. In addition, increases in background electrolyte reduced counterion desorption and resulted in a better surfactant bilayer formation.  相似文献   

11.
采用静态法研究D301R、D301G、D370和D315四种弱碱性阴离子交换树脂吸附柠檬酸法脱除SO2的解吸贫液中硫酸根的效果,分析吸附时间、柠檬酸浓度、树脂用量、pH等对硫酸根吸附量的影响,解吸时间、解吸碱液浓度对树脂解吸效果的影响,及多次吸附解吸循环再生对树脂吸附活性的影响。结果表明,D315在高浓度柠檬酸钠溶液(1.0 mol/L)中对SO42-有较好的脱除效果,当氢氧化钠浓度为1.5mol/L时,3min即可将SO42-解吸完全,在经过10轮吸附解吸循环再生后其活性下降,吸附能力降低约15%。  相似文献   

12.
氨基膦酸树脂吸附铈的研究   总被引:5,自引:1,他引:4  
研究了铈(Ⅲ)在氨基磷酸树脂上的吸附行为。试验结果在pH5.0时,静态饱和吸附容量为197mg/g干树脂;用2mol.L-1HCl洗脱,洗脱率为98.1%;表观速率常数k298=2.71×10-5s-1;等温吸附服从Freundlich经验式;吸附反应中的△Ho=50.0kJ.mol-1,△So=286J.mol-1.K-1,△Go=-35.1kJ.mol-1。树脂功能基与Ce3+的配比为2∶1;并用红外光谱探讨了树脂与铈的成键。  相似文献   

13.
N-methylimidazolium functionalized anion exchange resin in NO3-form(RNO3) was prepared and used for adsorption of Ce(IV)in nitric acid medium.The adsorption amount increased with shaking time increasing and the adsorption equilibrium was obtained within 180min.Ce(IV) was partially reduced to Ce(III) and the reduction percent of Ce(IV) increased with shaking time increasing.But RNO3 was morestable than other resins due to the high resistance to oxidation.A little increase of adsorption amount was found with ...  相似文献   

14.
The acid-catalyzed hydrolytic cleavage of the 5,6-epoxyspirostane derivatives by the cation exchange resin Dowex 50W X8 has been exploited with the goal of developing synthetic protocols toward 3,4,5,6-polyhydroxyspirostane analogs that can serve as intermediates to potential biologically active compounds. Whereas the diastereomers (25R)-5 alpha, 6 alpha-epoxyspirostan-22 alpha-O-3 beta-ol and (25R)-5 beta, 6 beta-epoxyspirostan-22 alpha-O-3 beta-ol yield two products, (25R)-6 beta-methoxyspirostan-22 alpha-O-3 beta, 5 alpha-diol and (25R)-spirostan-22 alpha-O-3 beta, 5 alpha, 6 beta-triol on Dowex treatment in water-methanol, the alpha- and beta-diastereomers of the 5,6-epoxy derivative of 3 beta, 4 beta-diol provide a single product, (25R)-3 beta, 6 beta-dihydroxy-5 alpha-spirostan-4-one, in good yields. The structures of these products have been confirmed using 1H NMR, 13C NMR, and 1H-1H J-correlated spectroscopies. Multifunctional product formation suggests tremendous utility of Dowex in steroid synthesis. The product formation has been rationalized on the basis of differential conformational constraints of the A/B rings of the different epoxides in directing the reaction course. The reaction shows an interesting example of stereoelectronic effect of a single hydroxy group in discriminating solvent participation.  相似文献   

15.
《Hydrometallurgy》2008,90(3-4):289-296
The paper presents results of the study for obtaining perrhenic acid from aqueous ammonium perrhenate solutions by ion exchange. Two ways of perrhenic acid synthesis have been examined: sorption of perrhenate anion on selected anion exchange resins (followed by elution of the sorbed rhenium as HReO4), and sorption of ammonium ion on selected cation exchange resins. The method of ammonium ion sorption on cation exchange resins has proved to be more effective. Using C 160 (H) cation exchange resin, perrhenic acid containing > 300 g/L of Re (after performing concentration in vacuum evaporator) has been obtained, with impurities concentration at the level of: < 1.0 mg/L NH4, ≤ 0.05 mg/L sodium, ≤ 0.20 mg/L potassium, ≤ 0.10 mg/L magnesium and ≤ 0.20 mg/L calcium.  相似文献   

16.
Experimental measurements have been made of the isotherms for the sorption and desorption of uranium from synthetic phosphoric acid solutions with two types of cation exchange resin. Work was performed with several D2EHPA/TOPO impregnated resins and with one commercially available ion exchange resin containing aminophosphonic acid groups. The effect of Fe2+, Fe3+ and Ca2+ on the effective capacity has been examined. Results show that D2EHPA/TOPO resins are n not affected by the presence of Fe2+ or of Ca2+. Ferrous ion, whichreduces uranium to the tetravalent oxidation state, prevents uranium sorption. The resin containing aminophosphonic acid groups possesses a higher effective capacity than D2EHPA/TOPO-based resins and was also not affected by the presence of Ca2+. Ferric and ferrous ions reduce the effective capacity considerably, though the resin still extracts U(IV).D2EHPA/TOPO-based resins can be eluted with 3 M H3PO4 at 40°C or 3 M H3PO4 solutions containing Fe2+. Ammonium carbonate was found to leach the organic extractants from the resin. The aminophosphonic acid resin can be eluted with (NH4)2CO3 at 20°C producing eluate solutions highly enriched in uranium. A conceptual flowsheet for uranium recovery is proposed.  相似文献   

17.
蒋月秀  郭尚伟  张雪  童张法 《稀土》2006,27(2):12-14
用铈对固体超强酸SO42-/TiO2/铝交联膨润土(SO42-/TiO2/Al-PILC)进行改性,制备了Ce-SO42-/TiO2/Al-PILC稀土超强酸,并采用XRD、低温N2吸附法及吡啶吸附红外等方法对其进行了结构、表面性能及酸性的表征.实验结果表明,铈引人SO42-/TiO2/Al-PILC超强酸对TiO2锐钛矿晶相的形成没有影响,但对锐钛矿晶相向金红石相的转变有促进作用,铈的引人使催化剂的酸强度及酸中心的数量略有下降,铈能有效地减少催化剂表面SO42-的流失量,从而提高了催化剂的活性稳定性.  相似文献   

18.
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.  相似文献   

19.
研究了采用特种阴离子交换树脂分离钼酸铵溶液中的钒。首先,采用静态吸附考察了料液平衡pH、料液钼浓度、氯离子浓度、吸附时间等因素对分离过程的影响;然后,进行动态交换实验,采用料液pH=8.01,接触时间60 min,处理料液为67倍树脂体积时,除钒率达到99.83%,树脂对V2O5工作交换容量为78.7 g/L,钒钼分离系数达到22522.9;用2 mol/L的NaOH溶液可以对负载树脂实现彻底解析。  相似文献   

20.
钨冶金离子交换新工艺研究   总被引:2,自引:1,他引:2  
针对我国钨冶金领域中通用的离子交换工艺存在的工作容量(漏穿容量)低,交前液中允许的WO3浓度、Cl^-浓度、OH^-浓度低等问题,系统研究了树脂改性处理后交换带的高度变化及对交前液中WO3、Cl^-、OH^-浓度的适应能力,发现改性树脂性能明显优于市购的201×7树脂,对工业料液而言,交前液浓度可提高2~3倍。在此基础上,开发了离子交换的新工艺,该工艺除采用新的改性树脂外,其设备及操作过程与经典工艺大体相同,交前液的浓度可成倍增加。  相似文献   

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