Encapsulation of Cyanex 302 with Alginate for Palladium Recovery

Abstract

A new generation of extractant impregnated resin has been elaborated by encapsulation of extractants in biopolymer capsules. The extractant forms the core of the spherical particle, while the biopolymer entraps the extractant in a shell. The immobilization can reduce the loss of extractant. Cyanex 302 (bis(2,4,4‐trimethylpentyl)monothiophosphinic acid) was efficiently immobilized into alginate capsules prepared by ionotropic gelation in CaCl2 solutions. The influence of a series of parameters on microcapsule preparation was investigated. Selected materials were tested for Pd(II) recovery from HCl solutions through the study of sorption isotherms and uptake kinetics.

Kinetic and Thermodynamic Studies of Precious Metals Sorption on Impregnated Lewatit VP OC 1026 from Chloride Solutions

“…In order to investigate kinetics of sorption of gold(III), platinum(IV) and palladium(II) ions on Lewatit VP OC 1026-Aliquat 336, the sorption kinetic models: pseudo-first-order (2), pseudo-second-order (3) and diffusion models as well as intra-particle diffusion model ( 4) and Dunwald-Wagner model (5) were used. Linear forms of these models are described by: ln q e À q t ð Þ ¼ lnq e À k 1 � t ðPFOÞ (2) q e = 0.8 mg/g Au(III) [25] XAD-7 impregnated by IL101 C = 0.01 M HCl, Agitation time: 7 days; q e = 87.9 mg/g Au(III) [26] XAD-1180 impregnated by IL101 C = 0.01 M HCl, Agitation time: 7 days; q e = 126 mg/g Au(III) [26] N-(diethylthiophosphoryl)-aza [18]crown-6 immobilized into Amberlite XAD-4 resin C = 0.05 M HCl q e = 42 mg/g Au(III) [27] Amberlite XAD-7 resin with a phenanthroline-derived diamide extractant N,N'diethyl-N,N'-ditolyl-2,9-diamide-1,10-phenanthroline (Et-Tol-DAPhen) C = 3 M HNO 3 q e = 74.6 mg/g Au(III) [28] XAD7HP impregnated by 2-mercaptobenzoxazole (MBO)/XAD7HP C = 0.5 M HNO 3 q e = 98.4 mg/g Pd(II) [29] Chitosan with dibenzo-18-crown-6-ether (Chitosan-DB18 C6) C o = 150 mg/L Pd(II), pH = 2 C o = 175 mg/L Pt(IV), pH = 2 q e = 17.6 mg/g Pd(II) q e = 98.4 mg/g Pt(IV) [30] Amberlite XAD7 functionalized with dibenzo-18-crown ether-6 (XAD7-DB18 C6) pH = 2, T = 298 K q e = 6.5 mg/g Pd(II) [31] Alginate-Cyanex 302 microcapsules 0.5 M HCl, T = 293 K q e = 22.1 mg/g Pd(II) [32] Monomer-impregnated adsorbent (MTCA XAD7) C o = 850 mg/L Pd(II), C = 1 M HCl q e = 7.9 mg/g Pd(II) [33] 2,2'-thiobisethanol dimethacrylate/ ethylene glycol dimethacrylate copolymer C = 4 M HCl q e = 100 mg/g Au(III) [34] Purogold™ A194 resin C = 1 M HNO 3 , T = 294 K q e = 0.76 mmol/ g Pd(II) [35] Lewatit VP OC 1026 impregnated by Aliquat 336 C = 0.1 M HCl, Agitation time: 24 h, T = 293 K, m:V = 0.1 g : 25 cm 3 q e = 94.1 mg/g Au(III) q e = 38.2 mg/g Pd(II) q e = 36.2 mg/g Pt(IV)…”

Highly Selective Adsorption and Recovery of Palladium from Spent Catalyst Wastewater by 1,4,7,10-Tetraazacyclododecane-Modified Mesoporous Silica

“…However, their development remains in its infancy and is often accompanied by a long recovery period and difficulty in selecting excellent strains. The wet process has become the most promising to complete enrichment and recovery of precious metals. − In the wet process, according to different mechanisms, it can be divided into adsorption, − ion exchange, complexation–extraction, and precipitation, ,− all of which are effective recovery methods. , Among them, the application of the adsorption method is gradually increasing with the advantages of fast kinetics, high enrichment coefficient, and reduced waste accumulation. In addition, the adsorption method has the advantages of simple operation, wide functionalization, and easy material availability, making it more practical and effective than other methods.…”