Martyna Rzelewska

Trihexyl(tetradecyl)phosphonium bromide as extractant for Rh(III), Ru(III) and Pt(IV) from chloride solutions‡

Ruthenium, rhodium and platinum are the most expensive of noble metals. As their natural sources are limited, it is important to develop an effective process for recovering Rh, Ru and Pt from waste sources. Their main suppliers are the following industries: chemical (spent catalysts), automotive, jewellery, dental and petrochemical. This paper presents studies on the extraction of Rh(III), Ru(III) and Pt(IV) from model aqueous chloride solutions using trihexyl(tetradecyl)phosphonium bromide (Cyphos IL 102). The effects of different parameters such as the influence of shaking time, HCl and NaCl concentrations in the feed solutions and also Cyphos IL 102 concentration in the organic phase, on the extraction of these metal ions were investigated. Additionally, the effect of the ageing of Rh(III) and Ru(III) chloride solutions on the extraction of these metal ions was studied.

Transport of iron ions from chloride solutions using cellulose triacetate matrix inclusion membranes with an ionic liquid carrier

In this study, liquid membranes denoted as polymer inclusion membranes (PIMs) consisting of cellulose triacetate (CTA) as a polymer matrix, o-nitrophenyl octyl ether (NPOE) as a plasticiser and phosphonium ionic liquids, trihexyltetradecylphosphonium chloride (Cyphos® IL 101) and trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl)phosphinate (Cyphos® IL 104), as carriers of metal ions were developed. The transport of Fe(II) and Fe(III) from chloride aqueous solutions across PIMs was investigated. It is shown that these phosphonium ionic liquids are effective carriers of Fe(III) ions through PIMs. While, for Fe(II), the highest value of extraction efficiency and recovery factor after 72 h does not exceed 40%, by contrast, the values of these parameters for Fe(III) transport ranged from 60% to almost 100%. Additionally, the results indicate the transport rate to be strongly influenced by the amount of carrier in the membrane. The highest initial flux of Fe(III) and permeability coefficient are noted for the membrane containing 40 mass % Cyphos® IL 101. However, it is shown that the transport of Fe(III) increases as the carrier content is increased then decreases at a content of the carrier equal to 40 mass %. It appears that the Fe(III)-carrier complex decomposes with difficulty at the interface of the membrane-receiving phase, hence leading to low values of recovery factor Fe(III).

Effect of composition and ageing of chloride solutions on extraction of Rh(III) and Ru(III) with phosphonium ionic liquids Cyphos IL 101 and IL 104

ABSTRACT Rhodium(III) and ruthenium(III) were extracted from chloride solutions with phosphonium ionic liquids trihexyl(tetradecyl)phosphonium chloride or trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate in toluene. Influence of HCl and NaCl presence in the feed and IL concentration in the organic phase were determined. Rh(III) transport appeared to be inefficient, while over 70% of Ru(III) was extracted from 3 M HCl. Ru(III) extraction was affected by the feed acidity and the type of extractant used. The spectra of the extracts indicated some changes in the structure of Rh(III) and Ru(III) complexes in the organic phase. Also, ageing of feed solutions on the extraction of Ru(III) and Rh(III) was studied.

Phosphonium ionic liquids as extractants for recovery of ruthenium(III) from acidic aqueous solutions

The aim of this work is to investigate extraction of ruthenium(III) from acidic aqueous solutions with phosphonium ionic liquids such as trihexyl(tetradecyl)phosphonium chloride (Cyphos IL 101), trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate (Cyphos IL 104) and tributyl(tetradecyl)phosphonium chloride (Cyphos IL 167) as extractants. The influence of HCl content in the feed solutions on extraction of Ru(III) was investigated. The research was performed for model solutions containing Ru(III) and a mixture of waste solutions containing Ru(III) and Rh(III). In addition, investigation of the type of extractant and its concentration in the organic phase on extraction of Ru(III) was carried out. Co-extraction of protons to the organic phase was determined. To the best of our knowledge, the extraction of Ru(III) with Cyphos IL 167 (tributyl(tetradecyl)phosphonium chloride) as an extractant has not yet been described in the scientific literature.

Wastes generated by automotive industry – Spent automotive catalysts

Abstract Rhodium, ruthenium, palladium, and platinum are classified as platinum group metals (PGM). A demand for PGM has increased in recent years. Their natural sources are limited, therefore it is important, and both from economical and environmental point of view, to develop effective process to recover PGM from waste/secondary sources, such as spent automotive catalysts. Pyrometallurgical methods have always been used for separation of PGM from various materials. However, recently, an increasing interest in hydrometallurgical techniques for the removal of precious metals from secondary sources has been noted. Among them, liquid-liquid extraction by contacting two liquid phases: aqueous solution of metal ions and organic solution of extractant is considered an efficient technique to separate valuable metal ions from solutions after leaching from spent catalysts.

Erratum to “Martyna Rzelewska, Monika Baczyńska, Magdalena Regel-Rosocka, Maciej Wiśniewski: Trihexyl(tetradecyl)phosphonium bromide as extractant for Rh(III), Ru(III) and Pt(IV) from chloride solutions”, Chemical Papers 70 (4) 454–460 (2016)

The preliminary results showed that Cyphos IL 102: i) extracts Ru(III), Rh(III) and Pt(IV) from the fresh feeds in the increasing order: Rh(III), Ru(III), Pt(IV), while the increasing order Ru(III), Rh(III), Pt(IV) was recorded for the aged feeds; ii) is the best extractant for the extraction of Pt(IV) (90 % of extracted Pt(IV)). The addition of NaCl to the feed solutions increases the extraction efficiency of all the three metal ions investigated. The extraction equilibrium was quickly established (after 5 min of shaking for Rh(III) and Ru(III) and only one minute of shaking for Pt(IV)). This indicates that Cyphos IL 102 exhibits one of the properties of a good extractant (fast kinetics of extraction). The HCl concentration in the feed solution does not significantly affect the extraction of Rh(III) and Pt(IV), while the extraction efficiency of Ru(III) decreases by half with the increasing HCl concentration in the fresh feed. The extraction efficiencies of Rh(III) and Ru(III) increase with the increase in the concentration of Cyphos IL 102 in the organic phase. However, it should be noted that the ageing of the feed solutions has a major impact on the extraction, especially for Ru(III) ions. The extraction efficiency of Ru(III) from the aged feeds containing 0.1 M HCl decreases six-fold, in comparison with the extraction of Ru(III) ions from the fresh solutions. By contrast, the extraction efficiency of Ru(III) from the aged feeds containing 5 M HCl shows no significant change. As the chemistry of Ru(III) and Rh(III) species in the aqueous feeds is very complex, further investigation of the mechanism of their extraction is in progress. It is possible to now propose the following general reaction (Eq. (1)) of Rh(III) or Ru(III) (denoted as M) extraction with Cyphos IL 102: