Palladium Recovery from Dilute Effluents using Biopolymer‐Immobilized Extractant

Abstract

Cyanex 301-immobilized material (prepared by immobilization into an alginate matrix) was tested for Pd sorption in 1 M HCl solutions with a special attention to sorption isotherms and uptake kinetics. This immobilized extractant had great affinity for Pd, as shown by the initial slope of the sorption isotherms. Sorption capacities as high as 150 mg Pd g 21 were obtained in 1 M HCl solutions. However, kinetics was slow, compared to conventional resins. The main limiting step in the process is the diffusion of metal ions into the matrix. The influence of parameters such as HCl concentration, NaCl addition, presence of Pt (as a competitor metal) has been checked. It appeared that sorption performance of Cyanex 301-immobilized material was hardly influenced by the addition of NaCl and by HCl concentration (below 2.5 M). The resin was remarkably selective for Pd, versus Pt, especially at 1 M HCl concentration. Loaded resins can be desorbed using thiourea solutions.

Extraction of Palladium from Acidic Chloride Media into Emulsion Liquid Membranes using LIX 984N-C<sup>®</sup>

“…Solvent extraction is a common hydrometallurgical process for the recovery of palladium from most industrial plants. The studies of palladium extraction using pyridinecarboxamides [3], thiosulfate, ACORGA ® CLX50 [4], hexadecylpyridinium [5], phosphonium [6], NH 4 + -dibenzyldiaza-18-crown-6 [7], Cyanex 471 [8], hydroxyoxime [9], Cyanex 301-immobilized material [10], α-benzoin-oximes and Cyphos ® IL/toluene [11], imidazolium nitrate immobilized resin [12] as extractants have been reported. However, the metal extraction rates by solvent extraction are generally low and the inventories of the organic solvent and metal extractant are substantial for the separation process.…”

Encapsulation of Cyanex 302 with Alginate for Palladium Recovery

“…Mimura et al prepared Cyanex 302/alginate beads by the homogeneous method: the extractant is immobilized in the biopolymer matrix; it was not encapsulated by a thin layer. They found that Pd(II) sorption was optimum when nitric acid concentration was close to 0.1 M. In the case of Cyanex 301 immobilized in alginate beads Guibal and Vincent observed a limited effect of HCl concentration in the range 0.1–2 M.…”

“…Mimura et al [30] prepared Cyanex 302/alginate beads by the homogeneous method: the extractant is immobilized in the biopolymer matrix; it was not encapsulated by a thin layer. They found that Pd(II) sorption was optimum when nitric acid concentration was close to 0.1 M. In the case of Cyanex 301 immobilized in alginate beads Guibal and Vincent [31] observed a limited effect of HCl concentration in the range 0.1-2 M. Figure 5 shows Pd(II) sorption isotherms using MC1 and MC2 for 0.5 M HCl solutions. The solid lines represent the modeling of the sorption isotherms with the Langmuir equation: this equation fits well experimental data.…”

Immobilization of extractants in biopolymer capsules for the synthesis of new resins: a focus on the encapsulation of tetraalkyl phosphonium ionic liquids

“…This principle was systematically used for preparing a series of extractant-immobilized capsules. 10,11,[29][30][31][32] The synthesis roughly consists of mixing the extractant with the biopolymer solution. The emulsion is then dropped into the coagulation/ neutralization solutions that allow the gelation of the biopolymer.…”

“…Guibal and Vincent tested a series of extractants (Cyanex 301, Cyanex 302 and Cyanex 471X, triisobutylphosphine sulfide) for immobilization in alginate gel beads. 29 The encapsulation procedure described by Mimura's group was modified to rule out the problems related to emulsion stability. The extractant was mixed with a gelatin solution in alkaline media (under increasing temperature, the gelatin melts).…”