Palladium and platinum sorption on a thiocarbamoyl‐derivative of chitosan

Abstract

Immobilizing thiourea onto chitosan allowed using the polymer for the recovery of platinum groups metals (PGMs) in acidic solutions (up to 1-2M HCl concentrations). At low HCl concentration protonated amine groups may sorb chloroanionic metal species (electrostatic attraction mechanism); however, most of sorption proceeds through chelation on sulfur containing groups (less sensitive to acidic conditions). The bi-site Langmuir equation was used for fitting sorption isotherms. The sorption of PGMs was weakly affected by the composition of the solution (presence of high concentration of anions and base metals). Maximum sorption capacities for Pd(II) and Pt(IV) ranged between 274 and 330 mg g À1 in 0.25M HCl solutions and decreased to 150-198 mg g À1 in 2M HCl solutions: Pd(II) sorption was systematically higher than Pt(IV) sorption. The pseudo-second rate equation was used for modeling the uptake kinetics. Agitation speed hardly affected uptake kinetics indicating that external diffusion resistance is not the rate controlling step. Desorption yield higher than 85% were obtained using thiourea in 0.1M HCl solution. The adsorbents could be reused for at least three cycles.

Zinc Ion Removal on Hybrid Pectin-Based Beads Containing Modified Poly(Methyl Methacrylate) Waste

“…It may be caused by worse fit of this model to experimental data (lower correlation coefficient: 0.973) than Freundlich one (R 2 = 0.996). Taking into account that hybrid sorbent contains two different sorbents (modified waste poly(methyl methacrylate) and pectin), thus two types of sorption sites with different adsorption energy may coexist, the parameters of the Langmuir bi-site model [ 51 ] were also estimated ( Table 3 ). A high correlation coefficient (0.996) proved this model describes sorption on hybrid sorbent much better than mono-site Langmuir equation.…”

“…Additionally, the parameters of Langmuir bi-site model [ 51 ] were estimated using the formula: q = ((q m1 × B 1 × c)/(1 + B 1 × c)) + ((q m2 × B 2 × c)/(1 + B 2 × c)) where: q m1 , q m2 —adsorption capacities for different sorption sites (mg/g), and B 1 , B 2 —equilibrium constants for different sorption sites that correspond to the adsorption energy (L/mg).…”

Selective Solid Phase Extraction for Separation and Preconcentration of Palladium from Gold Ore and Anode Slime after Complexation with a N4O2 Mixed Donor Ligand Derivative

“…The flow rate of sample solution through the column should be fast enough to perform the SPE in a short time, but it should be also slow enough to allow the interaction between the metal complexes and the resin as a packing material in the column 34–37. To study this parameter, 50 mL of the test solution was loaded on the column at different flow rates, from 1.5 to 25.0 mL/min.…”

A Comparison of Palladium Sorption Using Polyethylenimine Impregnated Alginate-Based and Carrageenan-Based Algal Beads

“…Both LD/PEI and CC/PEI beads show a much higher sorption capacity than unmodified biosorbents such as R. lanuginosum biomass [52], raw alginate beads, and algal beads [53], and comparable sorption levels compared to chemically modified alginate beads [54]. While modified XAD-7 resins [55][56][57] shown in the table present lower sorption capacities than CC/PEI beads, p-Sulfonatothiacalix [6] arene-impregnated IRA-411 or IRA-400 resins [57] show a much higher sorption capacity. However, the beads are environmentally friendly and low-cost; these properties also make them attractive for practical application.…”