Extraction of platinum(IV) by hydrophobic deep eutectic solvents based on trioctylphosphine oxide

Status and advances of deep eutectic solvents for metal separation and recovery

“…These results were originated from the promoted protonation of TOPO and the improved ability to attract Pt( iv ) in acidic media with strong ion strength of hydrogen. 159 Besides, the increasing concentration of Cl − with the addition of HCl would cause the common-ion effect, which weakens the hydrolysis of PtCl 6 2− and enhance its combination with the extractant. 160 Tang et al (2021) 115 also observed a similar declining trend of the extraction efficiency with the increase of aqueous pH when using the methyltrioctylammonium chloride ([N 8881 ]Cl) and 1-hexanol/hexanoic acid-based DESs to extract Pd( ii ) from HCl aqueous solution (as shown in Fig.…”

“…, pH, salinity, temperature, etc .). 113,159,173 Besides, the mechanical studies of the non-ionic type V DESs for metal extraction could be easier in the model systems. Take TOPO-based H(D)ESs for Pt( iv ) extraction as an example, TOPO: l-menthol, TOPO: 1-hexanol, and TOPO: 1-butanol were selected to investigate the interaction between H(D)ESs and PtCl 6 2− in a model system which was prepared by dissolving H 2 PtCl 6 in distilled water with hydrochloric acid.…”

“…Take TOPO-based H(D)ESs for Pt( iv ) extraction as an example, TOPO: l-menthol, TOPO: 1-hexanol, and TOPO: 1-butanol were selected to investigate the interaction between H(D)ESs and PtCl 6 2− in a model system which was prepared by dissolving H 2 PtCl 6 in distilled water with hydrochloric acid. 159 Because of the relatively simple compositions of the model system, the status and structure of PtCl 6 2− and H(D)ESs before and after extraction could be well characterized by UV-Vis and FT-IR spectra, which indicated that the status of PtCl 6 2− were maintained throughout the extraction process and the positive charge of the DESs phase during the extraction process originated from the protonation of phosphorus–oxygen double bond (PO) in TOPO. Accordingly, the mechanisms of the TOPO-based H(D)ESs for Pt( iv ) extraction can be summarized as ion-association and the reaction formulations as follows:…”

“…126 In contrast, the extraction of some other metals like Pt and Pd by DESs could be improved in acidic solutions with low pH values. 86,159 Liu et al (2021) 159 found that the extraction efficiency of Pt by H(D)ESs composed of TOPO and environmentally friendly organics (i.e., menthol, butanol, hexanoic acid, etc.) gradually rise with the increasing HCl concentration in the aqueous solutions (as shown in Fig.…”

Tailored ternary hydrophobic deep eutectic solvents for synergistic separation of yttrium from heavy rare earth elements

“…48,60,61 Compared with traditional molecular solvents and ILs, HDESs as a new generation of green solvents have a number of important advantages such as easier preparation processes, no need for purification, low cost, potential biodegradability and negligible toxicity, which highly adhere to the 12 principles of green chemistry. 52,56,62 The unique combination of physical and chemical properties of HDESs facilitates diverse applications in green chemistry, 63 such as the extraction of pharmaceuticals, 61 heavy metals recovery from wastewater, 64 the separation of carboxylic acids, 65 the selective extraction of boric acid, 66,67 liquid-liquid extraction and the separation of metal resources, [68][69][70][71][72] etc.…”