Selective Recovery Of Palladium Research Articles

Selective recovery of palladium from wastewater by modified PVC waste pipe

Green, efficient, and cost effective methods of recycling palladium (Pd) from wastewater have attracted increasing attention. In the present study, polyvinyl chloride (PVC) was utilized as a backbone for N-(3-aminopropyl)-imidazole to graft onto and yield an adsorbent suited for selective Pd recovery from wastewater by chlorine coordination. Batch experiments showed that the self-synthesized adsorbent had a Pd(II) adsorption rate of >99% at pH 1.0–3.0 and >93% in 4 min. The selectivity of the adsorbent in a complex mixed system containing high concentrations of typical base metals (CCu(II):CZn(II):CPd(II) = 66:33:1) was investigated, and the adsorbent demonstrated much higher selectivity for Pd (97.59%) than for Cu (0.52%) and Zn (2.96%). The adsorbent can also be reused as the adsorption rate remained above 99% after five cycles. Furthermore, waste PVC pipes also could be used as the synthetic raw material. The adsorbent demonstrated a high adsorption rate even when synthesized from discarded PVC pipes and the adsorption rate reached over 93% in 2 h and reached 95.15% at equilibrium in 4 h. Scanning electron microscopy and energy-dispersive spectrometry, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy were used to analyze the adsorption mechanism, which was attributed to electrostatic interaction and intermolecular interaction. The self-synthesized adsorbent is potentially applicable to the green recovery of Pd from wastewater owing to its high adsorption rate and selectivity.

Selective Recovery of Palladium from Plating Wastewater Using Chitosan Nanofiber Hydrogels

Selective Recovery of Palladium from Plating Wastewater Using Chitosan Nanofiber Hydrogels

Guanidinium-functionalized ionic covalent organic framework for selective and efficient recovery of palladium(II) from metallurgical wastewater

Efficient and selective recovery of palladium from acidic metallurgical wastewater is of great economic and environmental importance but remains challenging. Here, two novel ionic covalent organic frameworks (iCOFs), Tp-DGCl and BT-DGCl, were synthesized by reaction of 1,3-diaminoguanidine hydrochloride with 1,3,5-triformyphloroglucinol and benzene-1,3,5-triscarbaldehyde, respectively, and then applied to the recovery of Pd(II) from metallurgical wastewater. The maximum adsorption capacities of Tp-DGCl and BT-DGCl at pH 2.0 and 298.15 K were 342.1 mg g−1 and 231.1 mg g−1, which are higher than the majority of similar reported adsorbents. The adsorption isotherms of Pd(II) on iCOFs were highly consistent with the Langmuir isotherm model. Furthermore, the kinetics of the adsorptions by Tp-DGCl and BT-DGCl conformed to the quasi-second-order kinetic model, indicating that the controlling step of adsorption is chemical adsorption. Thermodynamic studies revealed that elevated temperatures are beneficial for the recovery of Pd(II). At the same time, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, zeta potential, and density functional theory computational analysis confirmed that electrostatic attraction and coordination are the main mechanisms for Pd(II) adsorption on iCOFs. This work not only highlights that the prepared iCOFs can be used as effective reusable adsorbents to selectively adsorb Pd(II) but also opens the door for the practical application of iCOFs in recovering palladium from complex metallurgical wastewater.

Selective Recovery of Palladium (II) from Metallurgical Wastewater Using Thiadiazole-Based Chloromethyl Polystyrene-Modified Adsorbent.

Selective adsorption of palladium from metallurgical wastewater containing Pt (IV), Rh (III), Ca2+, Cu2+, Fe3+, Ni2+, Pb2+, V3+, and Ti4+ has tremendous economic and environmental benefits. In this paper, a novel thiadiazole-based chloromethyl polystyrene-modified adsorbent, viz. 2, 5-bis-polystyrene-1,3,4-thiadiazole (PS-DMTD), was synthesized using chloromethyl polystyrene as the backbone. The experimental results show that PS-DMTD can selectively separate Pd (II) from metallurgical wastewater in a one-step adsorption process. The calculated saturation adsorption capacity of PS-DMTD for Pd (II) was 176.3 mg/g at 25 °C. The separation factors of βPd (II)/Mn+ (Mn+: Pt (IV), Rh (III), Ca2+, Cu2+, Fe3+, Ni2+, Pb2+, V3+, and Ti4+) were all higher than 1 × 104. FT-IR, XPS, and single-crystal X-ray diffraction showed that the adsorption of Pd (II) to PS-DMTD was primarily through a coordination mechanism. Density functional theory (DFT) calculations revealed that the other base metal ions could not coordinate with the PS-DMTD. Pt (IV) could not be adsorbed to PS-DMTD due to its strong chlorophilicity. Furthermore, Rh (III) existed as a polyhydrate, which inhibited Rh (III) diffusion toward the positively charged absorption sites on the PS-DMTD. These results highlight that PS-DMTD has broad application prospects in the recovery of Pd (II) from metallurgical wastewater.

Selective recovery of palladium from nuclear waste by covalent organic framework

Due to the resource merits and potential hazards, technologies for treating nuclear waste are of great significance. Recently in <i>Chem</i>, Wang and colleagues developed a covalent organic framework for precise recognition and highly efficient recovery of palladium from nuclear waste by synergistic binding strategy, which opens a bright avenue toward the development of efficient extractants for treating nuclear waste.

Selective recovery of palladium and rhodium by combined extraction and photocatalytic reduction

• The extraction efficiency of Pd(II) was higher than 99% for DDTC-ILs system. • The extraction mechanisms of DDTC-ILs with Pd(II) was elucidated. • Pure Pd or Rh nanoparticles can be obtained by the extraction-photocatalytic process. • PGMs recovery with photocatalytic reduction minimizes environmental impact. • DFT calculations were used to optimize extraction system. In this study, four novel functionalized ionic liquids ([C 4 mim][DDTC], [C 5 mim][DDTC], [C 6 mim][DDTC], and [BMPip][DDTC]) were synthesized and used for the selective extraction of Pd(II) from an HCl medium containing Pt(IV), Pd(II), and Rh(III). The extraction mechanism was investigated using Job’s plots, UV–Vis, SXRD, and MS analysis. A mechanistic investigation revealed the formation of hydrophobic extraction complexes Pd(DDTC) 2 and PdClDDTC via coordination between [DDTC] − and Pd(II). In addition, the solubility and polarity of the solutes were investigated using DFT calculations to determine the optimal extractant and diluent. From the results of the theoretical analysis, [C 5 mim][DDTC]/CHCl 3 was selected as the optimum system for the selective extraction of Pd(II). The effects that factors have on Pd(II) extraction, including temperature, [C 5 mim][DDTC] amount, HCl concentration, and O/A ratio, were investigated and optimized using single-factor and response surface experiments. Under the optimized conditions, Pd(II) extraction efficiencies were higher than 99%, and the separation factors (β Pd(II)/Pt(IV) and β Pd(II)/Rh(III) ) were greater than 10 4 . After extraction, Pd and Rh were directly recovered from the organic and aqueous phases via photocatalytic reduction, respectively. TEM, XPS, and PXRD results revealed that the resulting nanoparticles were Rh(0) or Pd(0). The recovery of Pd and Rh exceeded 95%. Overall, a simple hydrometallurgical process with low reagent consumption was developed to yield nanometer-scale Pd(0) and Rh(0) from simulated secondary resource leaching solutions.

Selective recovery of palladium by wool resin and woven wool fabric resinrbents

Protein fibers, including wool fibers, selectively adsorb precious-metal ions; hence, they can potentially be used in wastewater treatment applications. Herein, we examined metal-ion adsorption by woven wool fabric and wool resins, especially the adsorption of Pd(II). When woven wool fabrics are treated with chlorine, the cuticle layer is removed from the fiber surface; this treated fabric showed superior Pd(II)-adsorption performance compared with untreated fabric, with a Pd recovery of 81% from an aqueous solution containing 500 mg L−1 Pd(II) for 24 h at 25 °C, which is superior to that of lignin-based adsorbents. The chlorine-treated woven wool fabric and wool resin prepared from this fabric preferentially adsorb Pd when placed in simulated industrial wastewater, even if it contains a variety of other metal ions (e.g., Pd(II), Ni(II), and Cu(II)). Therefore, wool fabrics and resins produced from wool waste can be used as selective adsorbents for the recovery of precious metals such as Pd.

Rapid and selective recovery of palladium from platinum group metals and base metals using a thioamide-modified calix[4]arene extractant in environmentally friendly hydrocarbon fluids

A novel macrocyclic calix[4]arene extractant having a long alkyl chain thioamide, 25,26,27,28-tetrakis(N-n-octylthiocarbamoyl)methoxy-5,11,17,23-tetra-tert-butylcalix[4]arene (1), was synthesized from 25,26,27,28-tetrakis(N-n-octylcarbamoyl)methoxy-5,11,17,23-tetra-tert-butylcalix[4]arene (2) using Lawesson’s reagent. Extractant 1 was characterized using 1H NMR, 13C NMR, FT-IR spectroscopy, and elemental analysis. The Pd(II) extraction abilities of 1 and 2 were studied in high-boiling-point and environmentally friendly hydrocarbon diluents. Pd(II) extraction experiments were conducted using single-metal Pd(II) solutions, simulated mixed palladium group metal (PGM) solutions, and acid-leached automotive catalyst residue solutions. Different experimental conditions, including the shaking time, HCl/HNO3 concentration, Pd(II) concentration, extractant concentration, and the organic/aqueous phase ratio, were studied systematically. Extractant 1 showed very selective (> 99.9%) Pd(II) extraction from the mixed PGM/base metal solutions and the acid-leached automotive catalyst residue solution. Conversely, the Pd(II) extraction ability of extractant 2 was found to be negligible. Extractant 1 showed very fast extraction kinetics and a high extraction capacity as compared to those of the commercial extractant di-n-octyl sulfide. Effective stripping of Pd(II) from 1 was performed using HCI, HNO3, NH3, and HCl-thiourea solutions. Furthermore, 1 was successfully recycled over five extraction/stripping cycles. The Pd(II) extraction mechanism of 1 was studied using FT-IR spectroscopy. Extractant 1 exhibited very selective Pd(II) extraction and high acid stability, demonstrating its industrial applicability for the extraction of Pd(II) from leached automotive catalyst liquors containing PGMs and base metals.

Selective Recovery of Palladium from PGM Containing Hydrochloric Acid Solution Using Thiocarbamoyl-substituted Adsorbents

Selective Recovery of Palladium from PGM Containing Hydrochloric Acid Solution Using Thiocarbamoyl-substituted Adsorbents

Palladium and silver extraction with thiacalix[4]arenes and their acyclic analogs from carbonate and ammonia-carbonate solutions

A quantitative comparison of palladium and silver extraction with p-tert-butylthiacalix[4]arene (TCA) from nitric acid, carbonate, ammonia-carbonate, and ammonia solutions was carried out. It was shown that TCA under optimal conditions can be used for concurrent extraction of palladium and silver from carbonate systems of CARBEX process, selective recovery of palladium from nitric acid solutions, and selective silver extraction from ammonia-carbonate solutions. Metal distribution ratios and effective extraction constants decrease when the complex-forming ability of aqueous phase rises (Na2CO3 > NH4HCO3). The ammonia complexation of Ag+ is determining factor for silver, solution pH plays a certain role for palladium due to formation of hydroxo complexes.

Development of a solvent extraction system with 1,2-bis(2-methoxyethylthio)benzene for the selective separation of palladium(II) from secondary raw materials

The chelating dithioether 1,2-bis(2-methoxyethylthio)benzene, a novel solvent extractant for Pd(II), is aimed to be utilised in the selective recovery of palladium from spent automotive catalysts. For that, the extraction system has been further customised, including the choice of an appropriate diluent (1,2-dichlorobenzene) as well as an effective stripping agent (0.5M thiourea in 0.1M HCl), which both have been selected from a number of potential agents. It is shown in batch experiments that the selectivity for Pd(II) is maintained when the organic phase (10−2M 1,2-bis(2-methoxyethylthio)benzene in 1,2-dichlorobenzene) is used several times to extract an oxidising leach solution. According to the McCabe–Thiele plot two theoretical stages are needed to extract more than 98% of the Pd(II) contained in that solution. The calculation of the thermodynamic quantities ΔΗ°, ΔS° and ΔG° reveals that the reaction is entropy driven — the temperature has only a slight influence on the extraction yield. It is demonstrated that the mono-oxidised extractant has a catalytic effect on the extraction kinetics when the aqueous phase contains highly concentrated hydrochloric acid. HPLC measurements prove the presence of small quantities of 1-(2-methoxyethylsulfinyl)-2-(2-methoxyethylthio) benzene in the organic phase.

The use of a rotating cylinder electrode to selective recover palladium from acid solutions used to manufacture automotive catalytic converters

The reduction of palladium, rhodium and neodymium ions at concentrations of 0.94, 0.97 and 0.69 mol dm−3, respectively was studied in 1 mol dm−3 HNO3 or 1 mol dm−3 HCl, at a stainless steel and a vitreous carbon electrode, at 25 °C. At a vitreous carbon electrode in a solution containing rhodium and palladium ions in 1 mol dm−3 HCl electrolyte, the reduction of metal ions occurred at a similar potential to the formation of hydrogen gas, which impeded the selective separation of the two metals. At a stainless steel cathode in 1 mol dm−3 HNO3, palladium deposition occurred at a potential ≈0.35 V less negative than that of rhodium allowing the selective recovery of palladium. Neodymium ions were not electroactive in acidic chloride or nitrate media at pH 0. Using a solution obtained from a catalytic converter manufacturer containing palladium, rhodium and neodymium ions in 1 mol dm−3 HNO3, palladium ions were preferentially removed at 0.15 V versus SHE at an average cumulative current efficiency of 57%.

Recovery of palladium using chemically modified cedar wood powder

Japanese cedar wood powder (CWP) was chemically modified to a tertiary-amine-type adsorbent and studied for the selective recovery of Pd(II) from various industrial waters. Batch adsorption tests performed from 0.1 M to 5 M HCl and HNO 3 systems reveal stable performance with better results in HNO 3 medium. The maximum loading capacity for Pd(II) was studied in HCl as well as in HNO 3. A continuous-flow experiment taking a real industrial solution revealed the feasibility of using modified CWP for the selective uptake and preconcentration of traces of palladium contained in acidic effluents. In addition, stable adsorption performance even on long exposure to γ-irradiation and selective recovery of palladium from simulated high-level liquid waste (HLW) are important outcomes of the study.

Selective recovery of palladium from used aqua regia by hollow fiber supported with liquid membrane

This research study was aimed at recovering palladium from used aqua regia by means of a hollow fiber thoroughly supported with liquid membrane. The liquid membrane, consisting of two extractants—thioridazine HCl and oleic acid-solubilized in chloroform—was used to coat the rmcroporous hollow fiber throughout. Sodium nitrite, a stripping agent, which was fed through the shell side, flowed counter-currently with the feed solution fed via the tube side. The following factors were investigated: the concentrations of the two extractants and of sodium nitrite, the pH of used aqua regia, the flow rates of both the feed and stripping solution, and the number of runs in the hollow fiber module. It was found that after a 30-mmute operation, 29.10% of palladium ion was optimally recovered at 0.0005-M thioridazine and 0.05-M oleic acid. With reference to the precious metals recovered, the following order was recorded: Pd(II)>Pt(IV)>Cu(II)>Au(III). It was observed that synergistic extraction could be gained at the concentration level of the extradants, regulated in the experiment. The liquid membrane system had long-term stability and even after the third run, it could still recover palladium up to 65%.

Separation of palladium from simulated intermediate radioactive waste/chloroacetic acid/nitrate medium by IRA-410 and IRA-900 anion exchangers

Separation of palladium by strongly basic anion exchangers IRA-110 and IRA-900 from intermediate radioactive liquid waste in chloroacetic acid/nitrate medium containing thirteen elements have been achieved. Different conditions have been studied, the effect of NaNO3 as salt content, chloroacetic acid and hydrogen ion concentration have been investigated. Selective recovery of palladium from the [ILLW] solution was achieved using the column technique. The selectivity increased by using chloroacetic acid/nitrate than in nitrate medium. The elution of palladium was carried out via reduction with formic acid where the rate of the reduction process was increased by decreasing the formic acid concentration till 50% followed by dissolving the separated palladium by nitric acid.

Separation of Palladium and Silver from a Nitric Acid Solution by Liquid Surfactant Membranes

The recovery of palladium from a nitric acid solution containing silver has been conducted by application of liquid surfactant membranes (LSMs) containing LIX 860, a β-hydroxyoxime, as a mobile carrier in a stirred tank. The extraction equilibria of palladium and silver using several different extractants were also studied. Palladium was selectively extracted from a silver-containing liquor with LIX 860 while it was also observed that both palladium and silver were extractable with a sulfur-containing extractant. The recovery of palladium with LIX 860 was selectively achieved by using perchloric acid solution as the LSM internal phase dosed with thiourea. In the LSM operation, the effects of several chemical parameters on the selective recovery of palladium were studied. The use of hydrochloric acid as an internal receiving phase prevented the transport of silver into the emulsion due to the formation of silver chloride in the external feed solution. Commercially available Span 80 was found suitable for the selective extraction of palladium as a surfactant in LSM operation. Under optimum conditions, palladium was successfully separated from silver and concentrated into a receiving phase in W/O emulsions.

Selective recovery of palladium from a simulated industrial waste water by liquid surfactant membrane process

The selective recovery of palladium from an acidic solution of high iron concentration with liquid surfactant membranes (LSMs) containing di-2-ethylhexyl monothiophosphoric acid (commercial name MSP-8) as a carrier has been conducted in a batch and a continuous system using a mixer-settler. In the batch operation, the effects of several chemical species and their concentrations on the recovery of palladium were discussed. Using a relatively low concentration of PX100, stable emulsions were obtained and a high degree of palladium recovery was performed by a LSM technique. The concentration of thiourea employed as a stripping agent greatly affected the efficiency of palladium recovery. Under optimum conditions, palladium ions were separated from a large amount of iron ions and they were concentrated from the external feed aqueous solution into the inner receiving phase of W/O emulsions. Furthermore, an effective recovery of palladium could be achieved in a continuous operation using a mixer-settler under the optimum conditions for the batch system.

Selective separation of palladium from simulated intermediate radioactive waste nitrate by IRA-410 and IRA-900 anion exchangers

Selective efficient method have been for separation of palladium by strong basic anion exchangers IRA-410 and IRA-900 from intermediate radioactive nitrate medium. The different conditions for exchange behaviour of palladium from [ILLW] solutions containing numbre of elements were investigated by batch technique. Selective recovery of palladium from the [ILLW] solution was achieved using column technique. The elution of palladium was carried out via reduction with formic acid where the rate of the reduction process was increased by decreasing the formic acid concentration till 50% followed by dissolving the separated palladium by nitric acid.

Recovery of Palladium from an Industrial Wastewater Using Liquid Surfactant Membranes

Abstract Selective recovery of palladium from an industrial wastewater including a large amount of iron was studied by liquid surfactant membranes (LSMs) prepared with a sulfur-containing extractant as a carrier in a stirred cell. The extraction behavior of palladium and iron ions in liquid-liquid extraction was also investigated in order to choose an appropriate carrier for the LSM operations. Palladium ions were found to be extracted selectively over iron ions by using the sulfur-containing extractant from an acidic aqueous solution. The effects of several chemical species and operation factors on the recovery of palladium by LSMs were systematically examined with several kinds of sulfur-containing carriers and thiourea as a stripping reagent. The selection of carrier is a key factor for designing an efficient recovery process of palladium with an LSM technique. Di-2-ethylhexyl monothio-phosphoric acid (commercial name MSP-8) appears to be one of the best carriers currently available for palladium recovery using the LSM technique. Recovery of more than 95% palladium from a pseudoindustrial wastewater could be attained in a few minutes under optimum conditions.