The Application of 2,6-Bis(4-Methoxybenzoyl)-Diaminopyridine in Solvent Extraction and Polymer Membrane Separation for the Recovery of Au(III), Ag(I), Pd(II) and Pt(II) Ions from Aqueous Solutions

Abstract

The work describes the results of the first application of 2,6-bis(4-methoxybenzoyl)-diaminopyridine (L) for the recovery of noble metal ions (Au(III), Ag(I), Pd(II), Pt(II)) from aqueous solutions using two different separation processes: dynamic (classic solvent extraction) and static (polymer membranes). The stability constants of the complexes formed by the L with noble metal ions were determined using the spectrophotometry method. The results of the performed experiments clearly show that 2,6-bis(4-methoxybenzoyl)-diaminopyridine is an excellent extractant, as the recovery was over 99% for all studied noble metal ions. The efficiency of 2,6-bis(4-methoxybenzoyl)-diaminopyridine as a carrier in polymer membranes after 24 h of sorption was lower; the percentage of metal ions removal from the solutions (%Rs) decreased in following order: Ag(I) (94.89%) > Au(III) (63.46%) > Pt(II) (38.99%) > Pd(II) (23.82%). The results of the desorption processes carried out showed that the highest percentage of recovery was observed for gold and silver ions (over 96%) after 48 h. The results presented in this study indicate the potential practical applicability of 2,6-bis(4-methoxybenzoyl)-diaminopyridine in the solvent extraction and polymer membrane separation of noble metal ions from aqueous solutions (e.g., obtained as a result of WEEE leaching or industrial wastewater).

Sustainable and Selective Modern Methods of Noble Metal Recycling

“…Sequential transport of PtCl 6 2− and PdCl 4 2− is possible and it depends on the receiving solution while leaving [Rh III Cl 5 (H 2 O)] 2− in the feed solution that emphasizes the importance of specific ion pair interactions. [ 53 , 54 , 55 ] Ion exchange membranes utilising this specific ion pair interaction unlock potential for single‐step selective extraction and examples of Pt, [56] Pd,[ 57 , 58 ] and Rh [59] can be found emerging from recent literature. The significance of this method is illustrated in the gold and silver extraction domain which is covered later in this review but there is much potential for manipulations of the ionic interactions on a supported membrane to provide selective extraction of multiple noble metals.…”

Sustainable and Selective Modern Methods of Noble Metal Recycling

“…Sequential transport of PtCl 6 2À and PdCl 4 2À is possible and it depends on the receiving solution while leaving [Rh III Cl 5 (H 2 O)] 2À in the feed solution that emphasizes the importance of specific ion pair interactions. [53][54][55] Ion exchange membranes utilising this specific ion pair interaction unlock potential for single-step selective extraction and examples of Pt, [56] Pd, [57,58] and Rh [59] can be found emerging from recent literature. The significance of this method is illustrated in the gold and silver extraction domain which is covered later in this review but there is much potential for manipulations of the ionic interactions on a supported membrane to provide selective extraction of multiple noble metals.…”

Chelating Extractants for Metals

“…A comparison of extraction of metals by compound 29 with extractants containing other donor atoms (compound 13 and methylimino-bis-N,N′-dioctylacetamide 30) established that compound 13 shows high extraction ability in relation to hard acid metals U (VI), Pu (IV), Nd (III), and Zr (IV) due to the central oxygen donor atom [41]. The authors of [42] successfully extracted silver (I), palladium (II) and platinum (II) from aqueous solutions using 2,6-bis(4-methoxybenzoyl)-diaminopyridine 31 in chloroform with a more than 99% efficiency. In addition, polymer membranes based on poly(vinyl chloride) impregnated with compound 31 were used for extraction.…”

“…In the opinion of the authors, extraction occurred owing to the copper coordination to the nitrogen atom of the pyridinium ring and to the oxygen atom of the amide group in the ionized enol form, thus giving complex 32. The authors of [42] successfully extracted silver (I), palladium (II) and platinum (II) from aqueous solutions using 2,6-bis(4-methoxybenzoyl)-diaminopyridine 31 in chloroform with a more than 99% efficiency. In addition, polymer membranes based on poly(vinyl chloride) impregnated with compound 31 were used for extraction.…”