Recovery of Au(III), Pt(IV), and Pd(II) Using Pyridylethyl-Containing Polymers: Chitosan Derivatives vs Synthetic Polymers

Abstract

The sorption properties of N-2-(2-pyridyl)­ethylpolyethylenimine (PEPEI), N-2-(2-pyridylethylpolyallylamine (PEPAA), and N-2-(2-pyridyl)­ethylchitosan (PEC), synthesized via the aza-Michael reaction with 2-vinylpyridine and cross-linked with epichlorohydrin, have been investigated. It was shown that sorption capacities toward Pd­(II) and Pt­(IV) changed in the order PEPEI > PEC > PEPAA, with the maximal capacity of 4.6 mmol Pd/g for PEPEI. All the derivatives showed comparable efficiencies in Pt­(IV) uptake, with sorption capacities within the range 2.4–2.7 mmol/g. PEC was found to be the most efficient sorbent for Au­(III) recovery, with the sorption capacity equal to 4.9 mmol/g. XPS investigations have revealed that sorption of Au­(III) and Pt­(IV) by polymer precursors and all pyridylethyl derivatives is accompanied by changes in metal oxidation states. No direct correlation between sorption capacities and total ion-exchange capacities of the polymers was found, showing that noble-metal ions were recovered by pyridylethyl derivatives via chelation and/or redox sorption mechanisms rather than ion exchange. Pyridylethylation was beneficial to increase the efficiency of platinum and palladium elution after the sorption on PAA and PEI derivatives and of gold elution after sorption on the chitosan derivative, which enhances the potential of the application of these polymers in sorption/regeneration cycles.

Selective Recovery of Gold from E-Wastewater Using Poly-m-phenylenediamine Nanoparticles and Assembled Membranes

“…The gold removal performance of the PmPD nanoparticles was compared with other materials reported regarding their respective capacity, affinity, and acidic level (Table S1). As shown in Figure f, the PmPD nanoparticles exhibited a high gold adsorption capacity (2063.09 mg/g) and an extremely high-affinity K d (1.67 × 10 7 mL/g), outperforming most materials previously reported, including POSS-2, PEC, and CuS 38 nanoparticles. The exceptional selectivity of PmPD nanoparticles to gold can be attributed to the anion existing species of gold, which is different from other competing metals that mainly exist in cationic form.…”

“…Adsorption characteristics of PmPD particles for Au­(III) removal ([Au­(III)] 0 = 40 mg/L): (a) effect of pH on the Au adsorption rate; (b) isotherm of Au­(III) adsorption by PmPD particles fitted by Langmuir model (solid line); (c) zeta potential measurements of PmPD at pH ranging from 2 to 11; (d) removal of various cations by PmPD particles in a mixture containing different ions at equal concentration (50 mg/L); (e) distribution coefficients ( K d ) of various cation species; and (f) comparison of maximum adsorption capacities ( q max ) and distribution coefficient ( K d ) of PmPD particles with those of other reported adsorbents in the literature. − …”

Pyridine Derivatives as Biologically Active Precursors; Organics and Selected Coordination Complexes

“…Although the results were not exciting but further modification can lead to efficient material for the purpose. [91] Metal ion plays a crucial role in designing biologically active compounds, and it has been observed that changing central metal ion can drastically increase applicability in many cases. [92] Metal complexes particularly those containing Pd, Pt Au and Cu ions and Nligands are very promising against various human ailments including cancers.…”

Efficient recovery and recycling/upcycling of precious metals using hydrazide-functionalized star-shaped polymers

“…In particular, polymer-based adsorbents have been extensively employed owing to their high adsorption capacity, scalability, and chemical tunability 16 . Commercially available amine-functionalized polymers, such as branched poly(ethyleneimine) (bPEI) and poly(allylamine hydrochloride) (PAAm), are commonly used to fabricate PM adsorbents because of their high electrostatic affinity to PM ions 17 – 20 . However, these polymers cannot be used as standalone adsorbents because of their small particle size, which hinders their collection.…”