Polyurethane foams as selective sorbents for noble metals

Jones, Lynn; Nel, Iris; Koch, Klaus

doi:10.1016/s0003-2670(00)82437-x

Cited by 20 publications

(6 citation statements)

References 18 publications

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“…Normally, an additional preconcentration step must be performed after acid digestion during the analysis of ultra-low gold contents in rocks. The commonly used enrichment methods use precipitation [26,80,81,82,83], ion exchange resins [5,71,81,84,85,86,87,88], solvent extraction [27,89,90,91,92,93,94,95,96,97,98], polyurethane foam (PUF) [99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130], extraction chromatography [36,131,132,133], and solid adsorbents [134,135,…”

Section: Wet Acid Digestion Methodsmentioning

confidence: 99%

“…However, the majority of studies support the solvent extraction-based mechanism. Gesser [102], Oren [103], Lo and Chow [104], and Jones et al [105] examined the PUF adsorption of Ga, Fe, Sn, and Rh, and concluded that PUF was a “solid solvent-extractant”. In addition, a possible cation chelation mechanism was suggested by Hamon based on the results of his detailed studies on the PUF adsorption of Co thiocyanate and salts of several organic acids [106].…”

Section: Wet Acid Digestion Methodsmentioning

confidence: 99%

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Sample Digestion and Combined Preconcentration Methods for the Determination of Ultra-Low Gold Levels in Rocks

2019

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The gold abundance in basic rocks, which normally varies between 0.5 and 5 ppb, has served as a very important indicator in many geoscience studies, including those focused on the planetary differentiation, redistribution of elements during the crustal process, and ore genesis. However, because gold is a monoisotopic element that exhibits a nugget effect, it is very difficult to quantify its ultra-low levels in rocks, which significantly limits our understanding of the origin of gold and its circulation between the Earth crust, mantle, and core. In this work, we summarize various sample digestion and combined preconcentration methods for the determination of gold amounts in rocks. They include fire assay, fire assay combined with Te coprecipitation and instrumental neutron activation analysis (INAA) or laser ablation inductively coupled plasma mass spectrometry, fusion combined with Te coprecipitation and anion exchange resins, dry chlorination, wet acid digestion combined with precipitation, ion exchange resins, solvent extraction, polyurethane foam, extraction chromatography, novel solid adsorbents, and direct determination by INAA. In addition, the faced challenges and future perspectives in this field are discussed.

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Section: Wet Acid Digestion Methodsmentioning

confidence: 99%

Section: Wet Acid Digestion Methodsmentioning

confidence: 99%

Sample Digestion and Combined Preconcentration Methods for the Determination of Ultra-Low Gold Levels in Rocks

2019

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“…For example, the recovery of hardly sorbed rhodium essentially increases when tin chloride is added in a solution during sorption and extraction. 119,120 Microwaves, ultraviolet radiation or ultrasound can be used to facilitate noble metal sorption and to decrease the contact time under the preconcentration. 104,121 Thus, microwave-assisted sorption ensures a complete recovery of gold, palladium, platinum, rhodium, iridium and ruthenium by complexing sorbent POLYORGS 4 from hydrochloric and nitric acid solutions (1 M HCl or 1 M HNO3) within 15 min.…”

Section: -118mentioning

confidence: 99%

Trends in Sorption Preconcentration Combined with Noble Metal Determination

2007

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Nowadays much attention is being paid to the determination of trace amounts of noble metals in geological, industrial, biological and environmental samples. The most promising techniques, such as inductively coupled plasma atomic emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS) and electrothermal atomic absorption spectrometry (ETAAS) are characterized by high sensitivity. However, the accurate determination of trace noble metals has been limited by numerous interferences generated from the presence of matrix elements. To decrease, or eliminate, these interferences, the sorption preconcentration of noble metals is often used prior to their instrumental detection. A great number of hyphenated methods of noble metal determination using sorption preconcentration have been developed. This review describes the basic types of available sorbents, preconcentration procedures and preparations of the sorbent to the subsequent determination of noble metals. The specific features of instrumental techniques and examples of ETAAS, FAAS, ICP-AES, ICP-MS determinations after the sorption preconcentration of noble metals are considered. The references cited here were selected mostly from the period 1996 -2006.

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“…For a feed molar ratio of 10 : 1 Sn : Rh, the amount of co-extracted tin decreased from about 5 to 3É5 with an increase in acidity from 0É5 M to 5 M HCl. 8 The explanation provided has to do with the mass e †ect of the chloride ion in HCl and with the speciation of Sn(II)-chloride complexes. The e †ect of the Sn : Rh ratio in solution was also studied and it was found that a dramatic increase in loading capacity occurs as the Sn : Rh ratio is increased from 3 : 1 to 6 : 1.8 This corresponds to the conversion of the complexes to…”

Section: Extraction Of Rhodium-tin Complexesmentioning

confidence: 99%

Formation and extraction of Rh-Sn-Cl complexes with an alkylated 8-hydroxyquinoline

Benguerel

Demopoulos

1998

J. Chem. Technol. Biotechnol.

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:The work presented here focuses on the solution pretreatment and extraction stages of a solvent extraction system for rhodium from aqueous chloride solutions. The feed solution pretreatment stage involves a complexation reaction between the aqueous rhodium chloride complexes, and stannous chloride. Depending on the amount of)s tannous chloride used, at least two di †erent RhÈSn complexes are formed, either or Both of these respond well to extraction. with Kelex 100, the extractant investigated in this work. The extraction stage was found to be quantitative for rhodium and it was also found to be very rapid, with contact times of less than 5 min sufficient for rhodium extraction. The extraction mechanism was determined to be ion-pair formation with the protonated Kelex 100 molecules at a stoichiometry such that the overall charge in the organic phase is neutral, i.e.

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Polyurethane foams as selective sorbents for noble metals

Cited by 20 publications

References 18 publications

Sample Digestion and Combined Preconcentration Methods for the Determination of Ultra-Low Gold Levels in Rocks

Sample Digestion and Combined Preconcentration Methods for the Determination of Ultra-Low Gold Levels in Rocks

Trends in Sorption Preconcentration Combined with Noble Metal Determination

Formation and extraction of Rh-Sn-Cl complexes with an alkylated 8-hydroxyquinoline

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