摘要:

The lipophilic acyclic polyether carboxylic acid bls-l,8(2 -carboxy-3-naphthoxy)-3,6-dioxaoctane exhibits selectivity for Ra2+over Ba2+in competitive extractions into chloroform. Solubility characteristics of the compound suggest that the addition of branched alkyl substituents would be required to make it a practical separation agent.

ISSN:0736-6299    

DOI:10.1080/07366298608917874

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The organophosphine sulphides, tri-phenyl phosphine sulphide (TPPS), tri-n-butyl phosphine sulphide (TBPS) and N,N',N"-tri-n-hexyl phosphorothioic-triamide (THPS) have been investigated for their potential use as extractants for the recovery of fission product rhodium from aqueous nitric acid solutions. The ease with which the extractions proceed can be rationalised in terms of the polarisability of the P=S bond, and in the case of THPS, the extraction is shown to proceed via a solvating type mechanism. Equilibration times for the extraction are of the order of 3-6 hours.

ISSN:0736-6299    

DOI:10.1080/07366298608917875

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The extraction of nitric acid and uranyl nitrate with N,N-dibutyl-2-ethylhexyl amide (DBEHA) has been studied. The solvates formed in the organic phase are HN03-DBEHA and U02(NO3) 2.2DBEHA with the corresponding complex formation constants 0.05 and 20, respectively. The increase of uranyl nitrate distribution with the increase of nitric acid concentration in the aqueous phase, has been interpreted as the influence of nitrate ions on the extraction equilibrium.

ISSN:0736-6299    

DOI:10.1080/07366298608917876

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A number of neutral extractants containing the P(0)(CH2)nC(0)N raolety were evaluated for their ability to extract Am from nitric acid and their selectivity for Am over Fe and selected fission products. Extractants containing alkoxy, alkyl, and aryl substltuents were evaluated. Tetrachloroethylene was used as a diluent. Fission products selected for study were Y, Zr, Mo, Tc, Ru, Rh, Pd, La, Ce, Pr, Nd, Sra, and Eu. The conclusions drawn were that the most efficient and selective Am extractant contains a single carbon bridging group, one or two phenyl groups attached to the phosphorus atom and l9obutyl groups attached to the amide nitrogen.

ISSN:0736-6299    

DOI:10.1080/07366298608917877

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The number of water molecules associated with several metal chelates in water and then after being extracted into chloroform has been determined. A relationship between the number of water molecule adducts in the aqueous phase and the charge to volume ratio was determined for the acetylacetone system and an empirical equation developed.

ISSN:0736-6299    

DOI:10.1080/07366298608917878

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Span 80-LIX65N-LIX63 liquid surfactant membranes (LSMs) were used to extract copper from sulfate solutions at a pH of 2.0. The physico-chemical effects of Span 80 (sorbitan monooleate) were investigated with the aid of measurements of emulsion stability (as determined by leakage of K ions from the internal to the external phase), membrane phase viscosity, emulsion viscosity, and inter-facial tension. As the concentration of Span 80 was increased, copper extraction rate at first increased, rose through a maximum, and then decreased. The initial increase corresponded to a significant improvement in the stability of emulsion globules. Inter-facial tension measurements indicated that in order to achieve stable emulsion globules, a high adsorption density of the emulsi-fier at the emulsion interfaces in a LSM system was needed. It was further shown that a bulk phase emulsifier-extractant interaction at high extractant concentrations had an adverse effect on the stability of emulsion globules by removing emulsifier molecules from the interface. However, the high emulsifier adsorption density required for emulsion stability led to a decrease in the extractant concentration at the interface and therefore reduced the rate of copper complexation at the membrane phase/external phase interface. In addition, the viscosity measurements suggested that the decrease in metal extraction at emulsifier concentrations above the optimum might also be partly a result of the restricted movement of the internal phase droplets, an increase in the inter-facial viscosity, and/or a decrease in the membrane phase/external phase interfacial area.

ISSN:0736-6299    

DOI:10.1080/07366298608917879

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Certain neutral polymeric adsorbents such as the polyacry-lates XAD-7 and XAD-8 were discovered to exhibit modest capacities for the loadiny of gold from alkaline cyanide solutions. The adsorption characteristics of these resins were examined as a function of pH, ionic strength, and temperature. The experimental results suggest that adsorption occurs via ion pair formation and that the adsorption process can be described by the Freundlich adsorption equation. Interestingly, the polyacrylate resins show excellent selectivity for gold with respect to many other cyanoan-ions.

ISSN:0736-6299    

DOI:10.1080/07366298608917880

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Ion exchange equilibria of alkali metal ions (Li+, Na+, K+,, Rb+, and Cs+)H+, systems have been studied in MNO-j-HNOj media with ionic strength of 0.1 at 30, 45 and 60 °C on tin(IV) antimonate as a cation exchanger. The ion exchange isotherms have been measured for both forward and backward reactions by the batch technique. The isotherms showed S-shaped curves for all exchange systems studied. The selectivity coefficients (logarithmic scale) vary with the equivalent fraction XMof alkali metal ions in the exchanger and give two linear functions of XMwith a break point (XM= 0.14, except 0.04 for Li+, /H+) indicating two different exchanging sites. The selectivity sequence, Na+, ⩾ K+, ⩾ Rb+, ⩾ Cs+, ⩾ ⩾ Li, holds in the range of Xu= (0 - 0.04) and the sequence, Cs < Rb+, ⩾ K+, ⩾ Na+, < Li+, applies when XMis higher than 0.14.

ISSN:0736-6299    

DOI:10.1080/07366298608917881

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

H+/Na+ion-exchange in Ti(HP04)2.2H20 (γ TiP) was studied. The exchange isotherm, titration and hydrolysis curves at 25°C were obtained. In initially acidic or neutral solutions the 25% of the material exchange capacity was reached. The half-exchanged phase was obtained by additions of stoichiometric amounts of NaOH, with hydrolysis lower than 3% and at acidic equilibrium pH. For additions of NaOH over 4.0 me/g Y-TiP conversions higher than 50% were reached with an increase in the values of the equilibrium pH and the hydrolysis. The evolution of the solid was followed by X-ray diffraction. The substituted phases of samples dried in air at room temperature showed the following hydration degrees: ----H N ----------------------- conversion phase stored over P205 was dehydrated originating H1-5Na0.5 When i t is heated at 80°C-200°C i t transformed i n t o mixtures o f iTFi ( 9. 1 A ) and HNa (10.1 Å ).

ISSN:0736-6299    

DOI:10.1080/07366298608917882

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The H+/Na+ion-exchange process in Y Ti(HP04)22H20 was studied. Exchange isotherms, titration and hydrolysis curves were obtained at 25.0, 40.0 and 55.0 (+0.1)°C. Three different substitution processes and three hydrated crystalline phases of 25, 50 and 100% of conversion were detected. Equilibrium constants, free energies and entropies of the exchange reactions were determined.

ISSN:0736-6299    

DOI:10.1080/07366298608917883

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor