Polyurethane foam for the extraction of rhodium and its separation from iridium

The rate of reaction of rhodium with thiocyanate at 90 degrees in the presence of lithium chloride or sufficient hydrochloric acid and the subsequent extraction of the metal from hydrochloric acid medium by polyether-type polyurethane foam was investigated. The effect of the chloride salts of different cations decreased in the order Li(+) > Na(+) > K(+) indicating that Rh(SCN)(6)(3-) is extracted through a simple solvent-extraction mechanism rather than the "cation-chelation" mechanism. The separation of rhodium and iridium was also examined and the results indicated that in the presence of 5-fold excess of iridium, an average of 95 +/- 2% iridium remained in the aqueous phase while an average of 93 +/- 2% rhodium was retained by the foam.     

Extraction of osmium thiocyanate and its separation from ruthenium by polyurethane foam

A detailed investigation of the conditions for formation and extraction of the thiocyanate complex of osmium by polyether-type polyurethane foam is reported. The complex which formed in solution was extracted through the “cation-chelation” mechanism and distribution coefficients of more than 10⁴ were obtained. By using conditions which inhibit the formation of the osmium-thiocyanate complex, it was possible to leave 95% of osmium in the aqueous phase while extracting more than 95% of ruthenium into polyurethane foam.     

Polyurethane foams as selective sorbents for noble metals : Quantitative extraction and separation of rhodium from iridium in hydrochloric acid containing tin(II) chloride

The distribution of rhodium(III) between polyether-type polyurethane foam and 0.5–5.0 mol dm^?3 hydrochloric acid in the presence of small amounts of tin(II) chloride is described. The distribution of rhodium is affected by the extraction temperature, acid concentration and the Sn(II):Rh ratio. The capacity of the polyurethane foam for rhodium is in excess of 0.5 mmol g^?1. Rhodium is presumably sorbed in the form of a chloro(trichlorostannato)rhodium(III/I) complex anion. Iridium is not extracted by the foam under corresponding conditions and can be separated quantitatively from rhodium.     

Extraction of palladium thiocyanate with polyurethane foam

Conditions for the extraction of the thiocyanate complex of palladium by polyether-type polyurethane foam are reported. Distribution ratios of more than 10(6) with a capacity of about 0.8 mole per kg of foam were obtained. The palladium could be rapidly recovered from the foam with high efficiency by use of ammonia solution. The efficiency of palladium extraction depends on how well the cation associated with the complex fits into the polyether segment of the polyurethane foam.     

Transport extraction for trace element separation and preconcentration

Summary A new method of sorbent supported transport extraction based on the use of open-cell polyurethane foam sorbents in solvent sublation separation has been developed. The method has been shown to be effective for the separation and preconcentration of radioiodine and/or stable iodine from 41 of deionized, drinking (tap) and surface (river) waters using N-cetylpyridinium chloride as the cationic surfactant and N₂ carrier gas as the bubbling medium. A transport extraction efficiency of about 94% was obtained in 60 to 90 min; a 300-fold preconcentration was found for radioiodine as measured by direct radioactivity counting. Both radioiodine and stable iodine can be back-extracted from the polyurethane foam support (e.g. into acetone with an efficiency of almost 95%).Part II: This journal (1993) 346:905On leave from the Institute of Radioecology and Applied Nuclear Techniques, P.O. Box A-41, 04061 Koice, Slovakia     

Extraction of tin by the use of polyurethane foam

Three types of polyurethane foam were tested for the extraction of tin by static and flow systems. The amount of tin extracted varied with the type of foam, acid strength, and chloride and metal-ion concentrations. Quantitative extraction and recovery could be achieved. Open-cell polyurethane foam sponge is thought to act as a "solid solvent-extractant" for tin from aqueous solution. Distribution coefficients up to 5.6 x 10(3) were obtained and the capacity of the foam was up to 8% tin by weight.     

The extraction of uranium from acidic solutions by Adogen impregnated open cell polyurethane foam sponge

Open cell polyurethane foam coated with long chain tertiary amines (Adogen) has been shown to be an effective extractant for uranium in acidic solutions (3>pH>1). With dodecyl alcohol present uranium extraction at pH<1 is effective. The coated foam allowed column flow extraction at high flow rates but capacity studies indicated that only a fraction (about 1/3 to 1/2) of the amine was available for the complexation of the uranium. Interference of some common metal cations indicated that only Co(II) showed a significant adverse effect on the uranium extraction.     

The extraction of iridium and platinum from organic solvents by polyurethane foam

The feasibility of extracting iridium and platinum from organic solvents onto polyurethane foam was studied. Distribution ratios obtained were 1.1 x 10(4) for the extraction of iridium from ethyl acetate, 225 for the extraction of iridium from acetone and 4.8 x 1O(3) for the extraction of platinum from ethyl acetate. Capacities of about 16% w/w were obtained for extraction of iridium from ethyl acetate, and about 2.4% for extraction from acetone.     

PMBP-loaded polyurethane foam as an extractant for thorium nitrate from aqueous solution

A study on extraction of thorium with 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (PMBP)-loaded polyurethane foam is described. Open-cell polyurethane foam has proved to be effective as supporting material for PMBP. Thorium nitrate can be quantitatively extracted by PMBP-loaded polyurethane foam over a wide pH range. The effect of equilibrium time, pH, thorium concentration, various anions and flow-rate on the extraction efficiency of thorium is examined. A technique of extraction chromatography column with PMBP foam cylinder has been developed for trace thorium analysis of bulky water samples.     

分光光度法测定矿石中痕量金的分离富集方法研究 Ⅱ.泡沫塑料动态吸附

金矿石的类型复杂且金含量低,因此分离富集金的方法便是分析矿石中金的方法关键,我们在I报中研究了泡沫塑料(以下简称泡塑)静态分离富集金,并提出了以丙酮为解脱剂。丙酮不仅在常温下可有效地将金解脱,而且可直接用硫代米蚩酮显色分光光度法测定金,从而大大简化了分析手续。本文研究用泡塑柱动态分离富集金的方法,使金的分离和富集效果进一步得到改善,操作更为简捷,并有利于将分离富集过程仪器化和自动化。     

Two-stage extraction preconcentration and HPLC determination of phenol and 1-naphthol in aqueous solutions

The extraction of phenol and 1-naphthol with isomolar mixtures of ethyl acetate and hexane under batch conditions and with tributyl phosphate impregnated into a polyurethane foam under batch and dynamic conditions was studied. A procedure for determining phenol and 1-naphthol in aqueous samples was developed including their dynamic recovery on a column packed with polyurethane foam impregnated with tributyl phosphate, elution with a 0.1 M NaCl solution of pH 12.5–13.0, extraction with a mixture of ethyl acetate and hexane, and separation by normal-phase high-performance liquid chromatography (HPLC) with UV-detection. The overall preconcentration coefficient was 250. The detection limits were 2.5 μg/L. The relative error of determination was lower than 18%. The time of one determination was 2–2.5 h.     

Ruthenium- and rhodium-catalyzed direct carbonylation of the ortho C-H bond in the benzene ring of N-arylpyrazoles

The direct carbonylation of C-H bonds in the benzene ring of N-phenylpyrazoles via catalysis by ruthenium or rhodium complexes is described. The reaction of N-phenylpyrazoles with carbon monoxide and ethylene in the presence of Ru(3)(CO)(12) or Rh(4)(CO)(12) resulted in the site-selective carbonylation of the ortho C-H bonds in the benzene ring to give the corresponding ethyl ketones. A variety of functional groups on the benzene ring can be tolerated. N-Phenylpyrazoles have higher reactivities than would be expected, based on the pK(a) values of the conjugate acid of pyrazole. The choice of solvent for this reaction is significant, and N, N-dimethylacetamide (DMA) gives the best result.     

Strong-metal-support-interaction in titania-supported rhodium, ruthenium, and rhodium-ruthenium bimetallic catalysts

Titania-supported rhodium, ruthenium and rhodium-ruthenium catalysts were prepared by impregnation followed by reduction at 573 K (low temperature reduced-LTR) and 773 K (high temperature reduced — HTR). Temperature programmed desorption of hydrogen showed the existence of strong-metal-support-interaction (SMSI) in rhodium and ruthenium catalysts, but not in the bimetallic catalyst. In either case, metal-hydrogen bond strength had undergone change in going from an LTR to HTR sample. X-ray photoelectron spectroscopy (XPS) results did not show any electron transfer between metal and support in any of the catalysts but electron transfer from rhodium to ruthenium was indicated in the bimetallic catalyst under HTR.     

Extraction of uranium from aqueous solution by phosphonic acid-imbedded polyurethane foam

Phenylphosphonic acid was imbedded into the matrix of the polyurethane foam during the fabrication process of the polymer. The extraction of uranium by phosphonic acid-imbedded polyurethane foam and blank polyurethane (i.e., foam without phosphonic acid functional groups) was investigated. Phosphonic acid-imbedded foam showed superior extractability of uranium from solutions with pH=7.0+/-1.5 over a wide range of temperature.     

Partial separation of rhodium and iridium using polyurethane foam

Rhodium/III/ solutions react with tin/II/ chloride to form a short-lived yellow complex which is extracted by polyurethane foam. Iridium/IV/ solutions are decolourised by tin/II/ chloride but the metal is poorly extracted by foam. The rhodium/III/ complex is readily desorbed from foam using hydrochloric acid and acetone.     

OTPPTS对烯烃氢甲酰化反应的影响

 研究了水/有机两相体系中TPPTS(磺化三苯基膦)氧化为OTPPTS(氧化的TPPTS)对Rh/TPPTS催化烯烃氢甲酰化反应的影响. 结果表明,在己烯-1、辛烯-1和十二烯-1氢甲酰化反应中,当n(OTPPTS)/n(TPPTS)＜1时,对催化剂体系性能的影响较小,但当n(OTPPTS)/n(TPPTS)＞1时,将引起催化剂体系的活性、选择性和稳定性下降; 如果保持体系中TPPTS的含量一定,使n(TPPTS)/n(Rh)≥18,当n(OTPPTS)/n(Rh)＝20时,则对催化剂体系性能的影响不明显. 这说明生成的OTPPTS不是铑催化剂的毒物. TPPTS氧化为OTPPTS致使铑催化剂的活性和生成醛的选择性下降, 是由于TPPTS浓度的降低导致n(TPPTS)/n(Rh)值过低,使催化循环中各活性物种的平衡发生变化及铑配合物的稳定性变差所造成的结果.     

Extraction of aromatic acids and phenols by polyurethane foam

The extraction of several aromatic acids and phenols including salicylic acid, 8-hydroxyquinoline, 1-amino-2-naphthol-4-sulphonic acid and cinnamic acid in the presence of various protonated alkylamines, ammonia and alkali metal cations from aqueous solution by polyurethane foam has been investigated. These compounds are extracted only in the neutral form by a solvent extraction mechanism. The mechanism has been confirmed by the salting-out effect and pH studies. With the exception of 8-hydroxyquinoline, the compounds are more extractable by polyether foam than by polyester foam, suggesting that hydrogen bonding is stronger with the polyether foam.     

Mechanism of extraction of the palladium(ii) thiocyanate complex by polyether foam

The mechanism of sorption of the palladium(II) thiocyanate complex by polyether-type Polyurethane foam has been investigated. At low thiocyanate concentration, palladium is most likely extracted as Pd(SCN)(2). The results obtained in the presence of enough thiocyanate for formation of the Pd(SCN)(4)(2-) complex are in disagreement with several possible mechanisms for sorption of the anionic metal complex by the foam, such as adsorption, solvent extraction, ligand addition or exchange, and weak or strong base anion-exchange. The extraction of Pd(SCN)(4)(2-) at high pH increased in the order Li(+)< Na(+) < Cs(+)< Rb(+) < K(+)< NH(4)(+) which is in good relation with the "cation-chelation" mechanism. This mechanism was also found predominant in the extraction of Pd(SCN)(4)(2-) complex from hydrochloric acid solutions.     

Extraction of cobalt from thiocyanate solutions with polyurethane foam

The extraction of cobalt (II) from aqueous thiocyanate solutions with polyurethane foam has been extensively investigated. The extraction is enhanced by high thiocyanate concentration, high ionic strength and low temperature. A pH of 1.0-9.0 can be used for efficient extraction. Cobalt can be extracted at low concentration and the distribution coefficient is independent of foam weight. Several foam types and foam pretreatments have been examined. The effect of various substances added to the cobalt thiocyanate solutions has been investigated. Some of these substances caused either enhanced or decreased extractions by interacting with the polyurethane foam or by changing the solution chemistry.     

The separation of tellurium and selenium by polyurethane foam sorbents

Tellurium and selenium can be sorbed from hydrochloric acid and hydrobromic acid solution by both polyether and polyester-based polyurethane foam. Although some acid is needed, the substitution of sodium chloride or sodium bromide increases the extraction significantly. Tellurium is extracted rapidly with > 99% sorbed in 2 min from 1.0/5.0M and 2.0/4.0M hydrochloric acid/sodium bromide. Selenium can also be sorbed quantitatively but much more slowly so that a separation is possible based on the relative rates of extraction. The capacity of polyether foam is 3% by weight of tellurium.