Pd Adsorption Research Articles

Adsorption behavior of Au(III) and Pd(II) on persimmon tannin functionalized viscose fiber and the mechanism

A novel bio-adsorbent (DAVF-PT) was prepared by the introduction of persimmon tannin (PT) on the surface of viscose fiber (VF) through condensation reaction. The adsorbent was applied to the adsorption of Au(III) and Pd(II) from aqueous solution. Batch adsorption experiment found that the adsorption performance of DAVF-PT for Au(III) and Pd(II) was closely related to pH of solution, initial metal ion concentration as well as co-existing metal ions. The adsorption isotherms data of Au(III) and Pd(II) on DAVF-PT could be best explained by the Langmuir equation, and the fitted maximum adsorption amounts for Au(III) and Pd(II) were 535 mg/g and 214 mg/g, much higher than those similar adsorbents reported in the literatures. The thermodynamic study revealed that adsorption reaction was an endothermic, spontaneous and entropy increase process. Furthermore, the kinetics data of Au(III) and Pd(II) adsorption on DAVF-PT obeyed the Pseudo-second-order equation, indicating that the chemical adsorption was the mainly rate-limiting step. The EDS, XPS and XPD analysis confirmed that the gold and palladium ions were reduced to metallic state following adsorption, while the phenolic group was simultaneously converted into quinone group, indicating the potential use of this novel fiber-based adsorbent in the recovery of precious metal ions from wastewater.

Selective capture of Pd2+ by graft copolymer bearing LCST graft chain and metal adsorbing stem chain

A graft copolymer consisting of a stem chain for Pd adsorption and grafted chains for lower critical solution temperature transition efficiency separates Pd²⁺ from a mixture containing an excess amount of Ni²⁺. The polymer captures Pd²⁺ in the homogeneous mixture, and precipitates out by gentle heating (for example, just by grasping by hand).

Recovery of Pd(II), Ir(III) and Rh(III) from aqueous solutions with Brewer’s Yeast-functionalised bentonite

The scarcity of precious elements such as Pd(II), Ir(III) and Rh(III) has been increasing over the years hence, their recovery from wastewaters using efficient and cheap recovery techniques is becoming more important. In this study, the spent yeast collected after brewing was used to functionalise bentonite clay material to obtain very cheap material for recovery. The functionalised bentonite was characterised using Fourier transform infrared (FTIR) spectroscopy and element analyser. The textural properties of the natural and functionalised bentonite were determined. The effect of adsorbent dosage, pH, concentration, contact time and competing ions on the adsorption of Pd(II), Ir(III) and Rh(III) by yeast-functionalised bentonite was determined. The adsorbent dosage of 10 g L−1 and 360 min were chosen as optimum for this study. The pH of 2 was used since; it is the typical pH of the processing plant wastewater under investigation. The adsorption of Pd(II) and Ir(III) decreased as the pH increased whilst that of Rh(III) increased with pH. The adsorption of Pd(II) increased with concentration and this was attributed to the ability of Pd(II) to adsorb on different active sites of the adsorbent. This was substantiated by the adsorption isotherm study since, the adsorption of Pd(II) onto the adsorbent was best described by the Freundlich isotherm, meaning that the adsorption occurs on different active sites. Beyond 2 mg L−1, the adsorption capacity of Ir(III) and Rh(III) remained the same. In the presence of other ions, Pd(II) adsorption increases due to the synergistic Fe-Pd interaction but, the adsorption of Ir(III) and Rh(III) decreased by 57 and 17%, respectively. Therefore, to significantly recover Ir(III) and Rh(III), the old adsorbent which contains a significant amount of other elements should constantly be replaced by the new one and as other elements decrease, the adsorption of Ir(III) and Rh(III) will increase. The yeast-functionalised bentonite is a potential cheap adsorbent for the adsorption of precious elements.

Reactive adsorption of CO from low CO concentrations streams on the surface of Pd/CeO2 catalysts

Reformate gas mixtures introduced into PEM fuel cells may contain traces of CO which can irreversibly poison electrocatalysts. A means to eliminate such traces of CO from reformate mixtures via reactive adsorption onto solid catalysts is described. The reactive adsorption/desorption characteristics of CO were investigated over Pd/CeO2 catalysts with respect of Pd loading and adsorption temperature employing in situ FTIR and transient MS techniques. Results showed that CO adsorption is enhanced with increasing Pd content or decreasing adsorption temperature. Production of CO2 during CO-TPD occurs in a bifuntional manner with the participation of both the metallic phase and the support. Although the adsorption of CO is limited upon interaction of 0.25%Pd/CeO2 catalyst with a reformate mixture, results demonstrate that elimination of residual CO, present in the exit of methanation (or oxidation) reactor, is feasible via successive cycles of CO adsorption and oxidation at 40 °C.

Modified tunicate nanocellulose liquid crystalline fiber as closed loop for recycling platinum-group metals

Rising demand and elemental rarity requires the recycling of precious metals such as platinum group elements (PGMs). Recently, biosorption has been focused on the capability of recovering precious metals, but in practice, recycling is inefficient or far away from a closed-loop material system. Here we use a polyethylenimine (PEI)-grafted spun-fiber made of cellulose nanofibril (CNF) extracted from a tunicate as a biosorbent for PGMs. Liquid crystallinity (LC) of TCNF suspension appears to contribute the generation of well-developed open porous structure in the fiber. We show the fiber has the selectivity and high capacity of Pt (120.2 mg/g, 86%) and Pd (26.5 mg/g, 74.2%) adsorption under the presence of other metals in simulated automobile waste. The adsorbed Pt and Pd with nano-scale clusters were uniformly distributed on the porous surface, which were directly applied as a catalyst. These results propose an easy approach to recover precious metals and reuse them directly, thereby closing loops of metal recycling.

Dual interfacial synergism in Au-Pd/ZnIn2S4 for promoting photocatalytic selective oxidation of aromatic alcohol

Visible-light-responsive semiconductor decorated with bi-metal nanoparticles synergistic photocatalysts are promising in photocatalysis. Herein, bi-metal nanoparticles Au-Pd decorated ZnIn2S4 nanosheets photocatalytic system was constructed and applied in reaction of photocatalytic selective oxidation of of aromatic alcohols. Various parameters including loading ratio of two metal, loading amount, solvents, time, reactant were investigated. The optimal 0.5 wt% Au-Pd/ZnIn2S4 photocatalysts was founded to exhibit the highest photocatalytic activity, which is 1.5, 2.0 and 1.3 times higher than pristine ZnIn2S4, Au/ZnIn2S4 and Pd/ZnIn2S4, respectively. Characterization results confirmed enhanced visible-light harvesting capability as well as superior photoinduced carriers’s separation and transfer behavior, enhanced O2 adsorption and reduction ability of Pd and surface reaction kinetics account for enhanced photocatalytic activity, in addition, which ascribed to dual metal synergistic effect and metal-semiconductor interaction in Au-Pd/ZnIn2S4 system. Finally, the corresponding reactive radical species was confirmed by ESR and other method. Based on the experimental data and analysis, possible reaction mechanism is proposed. The photogenerated h+, O2− and carbon centered radicals are responsible for the reaction. This systemic work shed light on the bi-metal decorated semiconductor photocatalyst, where metal-metal interaction as well as metal-semiconductor cooperated together to improve the performance of catalysts in visible-light-driven organic transformations.

Highly Efficient Separation/Recycling Palladium(II) Ions from Aqueous Solutions by Silica Gel-Coated Graphene Oxide Modified with Mercapto Groups

The separation and recovery of precious metals from secondary resources is an extremely important and challenging task. Herein, a novel sorbent is successfully prepared by chemical grafting and utilized for the extraction and separation of Pd(II) ions from aqueous solutions. Various characterization techniques, including Fourier transform infrared spectroscopy, scanning electron microscopy, Brunauer–Emmett–Teller, X-ray photoelectron spectroscopy, and element analysis, are employed to study the structure, morphology, porous nature, and chemical composition of the as-prepared SiO2@GO-SH nanocomposites. The adsorption of Pd(II) ions on the SiO2@GO-SH can be described by the pseudo-second-order model and Langmuir isotherm model. The adsorption equilibrium has been attained within 90 min and the maximum adsorption capacity of 423.2 mg g−1 was attained at pH 3.5 and T = 308 K. The results reveal that SiO2@GO-SH exhibits an excellent adsorption performance towards Pd(II) ions. In addition, we have proposed the adsorption mechanism for Pd(II) ions on the SiO2@GO-SH surface. The adsorption of Pd(II) in SiO2@GO-SH is a chemisorption process, where partial adsorbed Pd(II) ions are reduced to Pd(0) by functional groups (-SH) in the SiO2@GO-SH. The results indicate that SiO2@GO-SH can serve as a promising sorbent for the efficient separation and recovery of palladium from the palladium-containing secondary resources.

Adsorption and fractionation of Pt, Pd and Rh onto inorganic microparticles and the effects of macromolecular organic compounds in seawater

Adsorption and fractionation of Pt, Pd and Rh (defined here as platinum group elements, PGEs) onto the representative inorganic microparticles, including Fe2O3, MnO2, CaCO3, SiO2, Al2O3 and kaolinite in seawater were investigated. The effects of macromolecular organic compounds (MOCs) as the representatives of organic matter, including humic acids (HA), bovine serum albumin (BSA) and carrageenan, on the adsorption were also studied considering that organic matter is ubiquitous in seawater and indispensable to marine biogeochemical cycles. In the absence of MOCs, the representative mineral particles Fe2O3 and MnO2 had the strongest interaction with PGEs. The adsorption of PGEs onto the representative biogenic particles SiO2 and CaCO3 and lithogenic particles Al2O3 and kaolinite was similar or weaker than onto the mineral particles. MOCs inhibited the interaction between PGEs and the particles except for Pt and Pd onto the biogenic particles in artificial seawater. This impediment may be closely related to the interaction between particles, MOCs and elements. The partition coefficient (log Kd) of Pt was similar (∼4.0) in the presence of MOCs, indicating that the complexation between Pt and MOCs was less important than hydrolysis or adsorption onto the acid oxide particle surface. Rh tended to fractionate onto the mineral and lithogenic particles in the presence of HA and carrageenan, while Pd was more likely to fractionate onto the biogenic particles. However, BSA enhanced the fractionation tendency of Pd onto the mineral particles. The results indicate that the adsorption behavior of Pd onto inorganic particles was significantly affected by the composition or the type of MOCs. Hence, the interaction between PGEs and inorganic particles may be greatly affected by the macromolecular organic matter in the ocean.

Palladium Supported on Porous Chitosan-Graphene Oxide Aerogels as Highly Efficient Catalysts for Hydrogen Generation from Formate.

Adsorption of Pd(NH3)42+ in preformed chitosan–graphene oxide (CS-GO) beads and their subsequent reduction with NaBH4 afford well-dispersed, high dispersion (~21%) of uniformly sized Pd nanoparticles (~1.7 nm). The resulting Pd/CS-GO exhibits interesting catalytic activity for hydrogen generation by ammonium formate decomposition. The optimal GO proportion of 7 wt% allows reaching, at 60 °C, a turnover frequency above 2200 h−1—being outstanding among the highest values reported for this process to date. Interestingly, no formation of CO or CH4 was detected. The catalyst did not leach, although it underwent gradual deactivation, probably caused by the increase in the Pd average size that became over 3 nm after three uses. Our results are relevant in the context of efficient on-board hydrogen generation from liquid organic hydrogen carriers in transportation.

Adsorption of Pd(II) onto Zr(IV) Based Metal-Organic Framework UIO-66-NH<sub>2</sub> from Hydrochloric Acid Solution

Metal-organic frameworks are used in many applications, such as gas separation, catalysis, and the synthesis of nanomaterials. Metal-organic frameworks show superior stability at high temperature, which makes them potentially useful for the adsorption of metal ions from leaching solutions at high temperature. In this work, UIO-66-NH2, a zirconium(IV) based metal-organic framework, was employed for the adsorption of Pd(II) from hydrochloric acid solutions. The adsorption percentage of Pd(II) decreased rapidly as HCl concentration increased from 0.2 M to 1 M and was negligible beyond 3 M. It was found that some of the UIO-66-NH2 was disrupted in the strong HCl solution and released Zr(IV) into the solution. The effect of chloride ion concentration on the adsorption of Pd(II) was investigated. The adsorption percentage of Pd(II) by UIO-66-NH2 decreased rapidly as chloride ion concentration increased. The adsorption of Pd(II) onto UIO-66-NH2 followed the Langmuir isotherm and reached equilibrium within 2 hours under these experimental conditions. The kinetic data for the adsorption of Pd(II) onto UIO-66-NH2 agreed well with a pseudo-second order kinetic model. The initial rate constant at 0.2 M HCl was 15.2 mg/g·min and decreased to 2.7 mg/g·min at 1.0 M HCl. More work is necessary to improve the stability of UIO-66-NH2 in strong HCl solution and to make the metalorganic framework at lower cost. Key words: metal-organic framework, palladium(II), HCl, adsorption

Au(III), Pd(II) and Pt(IV) adsorption on amino-functionalized magnetic sorbents: Behaviors and cycling separation routines

In this paper, superparamagnetic Fe3O4@SiO2-NH2 nanoparticles were applied to adsorb Au(III)/Pd(II)/Pt(IV) in HCl medium. The successful synthesis of Fe3O4@SiO2-NH2 was characterized through TEM, SEM and FT-IR. Electrostatic interaction between magnetic NPs and metal anions was proposed as the main adsorption mechanism by zeta potential analysis. Maximum adsorption capacities and adsorption behaviors under metal anions concentrations, acidity, NaCl, kinetic and isotherm models were investigated. Notably, the Fe3O4@SiO2-NH2 shows the excellent acidity and salinity resistance on Au(III), Pd(II) adsorption. The separation routine among Au(III), Pd(II) and Pt(IV) was proposed. As investigated, Pt(IV) could be isolated due to the less adsorption amount onto Fe3O4@SiO2-NH2 (≤1%). Then, the adsorbed Au(III) was eluted selectively by HCl + N-hexanol alcohol + ethanol + H2O2 mixing solution. Then, the adsorbed Pd(II) was completely eluted by thiourea solution. The recovery efficiencies of Au(III), Pd(II) and Pt(IV) were kept over 92%, 97% and 94% respectively, during 5 turns of cycling separation experiments. Total loss amount of Fe is around 7%. Hence that, the particle demonstrates the good stability and high adsorption capacity, which possess great potential for practical Au(III), Pd(II) and Pt(IV) separation.

Selective separation of Pd(II) through ion exchange and oxidation-reduction with hexacyanoferrates from high-level liquid waste

A macro porous silica-based nickel hexacyanoferrate (KNiHC/SiO2) adsorbent was synthesized for separation of palladium (Pd(II)) from high-level liquid waste (HLLW). Based on XPS analysis, the Pd 3d5/2 spectrum at 344.4 eV corresponds to metallic palladium Pd(0), indicating that ion-exchange and redox reactions occur in the adsorption of Pd. Mercury intrusion porosimeter (MIP) test results show that the average pore size of KNiHC/SiO2 is 37.6 nm. The adsorption of KNiHC/SiO2 for Pd(II) reaches the equilibrium state within 1 h and follows the pseudo-second-order kinetic model, which indicates chemical adsorption. The maximum adsorption capacity of the adsorbent for Pd(II) in the mixture of 1 M NaNO3 and 3 M HNO3 is 46.09 mg/g. The experimental data fit well with the Langmuir and Redlich-Peterson isotherm models. Furthermore, KNiHC/SiO2 exhibits high selectivity toward Pd(II) over co-existing noble metals, namely, Rh(III) and Ru(III) within a wide range of HNO3 concentrations. The sharp S-shaped breakthrough curves in different feed flow rates suggest the excellent dynamic adsorption performance of the adsorbent in column systems.

Removal of Platinum and Palladium from Wastewater by Means of Biosorption on Fungi Aspergillus sp. and Yeast Saccharomyces sp.

The emission of platinum group metals from different sources has caused elevated concentrations of platinum and palladium in samples of airborne particulate matter, soil, surface waters and sewage sludge. The ability of biomass of Aspergillus sp. and yeast Saccharomyces sp. for removal of Pt(IV) and Pd(II) from environmental samples was studied in this work. The pH of the solution, the mass of biosorbent, and contact time were optimized. The Langmuir and Freundlich adsorption isotherms and kinetic results were used for interpretation of the process equilibrium of Pt(IV) and Pd(II) on both microorganisms. The maximal efficiency of retention of Pt(IV) on yeast and fungi was obtained at acidic solutions (pH 2.0 for Pt(IV) and pH 2.5–3.5 for Pd(II)). The equilibrium of the biosorption process was attained within 45 min. The best interpretation for the experimental data was given by the Langmuir isotherm. Kinetics of the Pt and Pd adsorption process suit well the pseudo-second-order kinetics model. Fungi Aspergillus sp. shows higher adsorption capacity for both metals than yeast Saccharomyces sp. The maximum adsorption capacity of fungi was 5.49 mg g−1 for Pt(IV) and 4.28 mg g−1 for Pd(II). The fungi possess the ability for efficient removal of studied ions from different wastewater samples (sewage and road run-off water). It was also demonstrated, that quantitative recovery of Pd from industrial wastes could be obtained by biosorption using Aspergillus sp.

Combinatorial optimality of functional groups, process parameters, and Pd(II) adsorption-desorption characteristics for commercial anion exchange resins-synthetic electroless plating systems.

Considering combinatorial optimality of functional group analysis, speciation, solution chemistry complexity, Pd(II) adsorption-desorption characteristics, this article addresses the competence and efficacy of anion exchange resins namely Amberlite IRA958, Dowex Marathon MSA, Lewatit TP214, and Amberlyst A21 commercial resins. Based on preliminary batch adsorption experiments conducted in the range of 2-10 pH, 0.2-2 g L-1 adsorbent dosage, and 5-1080-min contact time, the optimal adsorption process parameters refer to 4 pH, 1.6, and 1.4 g L-1 adsorbent dosage, and 840- and 720-min contact time for Amberlite IRA958 and Dowex Marathon MSA resins, respectively. Among alternate models, the best-fit models refer to the Freundlich isotherm and pseudo-second-order kinetic models to represent Pd(II) adsorption data obtained for both Dowex Marathon MSA and Amberlite IRA958 resins. Based on the Langmuir isotherm, the maximum monolayer adsorption capacity was evaluated to be 185.16 and 166.67 mg g-1 for Dowex Marathon MSA and Amberlite IRA958 resins, respectively. For model electroless plating solutions as adsorbate system possessing desired solution chemistry complexity and resin cost, nitrogen- and oxygen-containing Amberlyst A21 resin is concluded to be optimal resin. This is not in agreement with the generalized rule of thumb that considers sulfur-nitrogen functional group containing commercial resins to be effective than resins with nitrogen-oxygen functional groups. Due to functional group interactions with the noble metal, no other by-products or exchanged chemicals have been produced in due course of Pd(II) adsorption process, which can be also regarded as an added advantage of the process. Graphical abstract.

Sulfur-doped porous carbon supported palladium catalyst for high selective o-chloro-nitrobenzene hydrogenation

Sulfur-modified carbon support can effectively modulate the performance of the metal catalyst. Here we prepared a sulfur-doped mesoporous carbon material (CSx) through carbonization of poly(sodium p-styrenesulfonate or p-styrenesulfonate co-maleate), which was supported with Pd and employed for the selective hydrogenation of o-chloro-nitrobenzene (o-CNB) to o-chloro-aniline (o-CAN). Such catalyst shows almost 100% selectivity of o-CAN at 100% o-CNB conversion (performed in a batch reactor: t = 210 min, No-CNB,0/mcat =0.63 mol/gcat). The stability (recyclability) study of the optimal catalyst shows that the catalyst can be reused for at least six times without decreasing the selectivity (100% conversion can be achieved with slightly prolonged reaction time). We suggest that the electronic effect between the S and Pd, which reduces the hydrogen adsorption and dissociation ability of Pd, to be responsible for the excellent selectivity, and the formation of C–S covalent bond to be responsible for the good stability.

Dialdehyde carboxymethyl cellulose cross-linked chitosan for the recovery of palladium and platinum from aqueous solution

Platinum (Pt) and palladium (Pd) have widespread applications, such as in catalysts, jewelry, fuel cells, and electronics because of their favorable physical and chemical properties. Recovery of Pt and Pd from secondary sources is of great concern due to the increased market demand and limitation of the natural reserves of these precious metals. The aim of this research is to achieve recovery of Pt and Pd ions from dilute aqueous solution using dialdehyde of carboxymethyl cellulose (DCMC) crosslinked chitosan (Ch-DCMC). The DCMC was prepared by periodate oxidation of carboxymethyl cellulose (CMC). Both the DCMC and Ch-DCMC were characterized before and after Pt or Pd adsorption using Fourier-transformed infrared (FTIR) spectroscopy, X-ray powder diffraction (XRPD), and scanning electron microscopy (SEM). The effect of cross-linking ratios of chitosan and DCMC (1:1, 1:0.8, 1:0.5, 1:0.25 and 1:0.1) on the Pt and Pd recovery was studied. The optimal cross-linking ratio was found to be 1:0.25 (chitosan: DCMC) with maximum adsorption capacity of 80.8 mg/g Pt and 89.4 mg/g Pd. High selectivity for Pt and Pd compared to base metals and common anions was achieved.

Highly Selective Adsorption of New Bis-Opened-Triazine Materials Hybridized with a Cross-Linked Polymer Support for Palladium and Some Typical Coexisting Metals

A novel polymer hybrid bis-opened-triazine adsorbent, BOTZX, was prepared by impregnation and immobilization. It was achieved through the in situ introduction of a new monopyridine-derived bis-opened-triazine ligand, BOTZ, into the pores of the cross-linked inert polymer carrier under vacuum hybridization. The adsorption of 20 representative metals on BOTZX was studied over the ranges of 0.4 to 6.0 M HNO3 and 298 to 318 K. BOTZX had strong uptake ability and high selectivity for Pd over others except for Zr. The removal efficiency was more than 99.8% for Pd and less than 0.11% for others, except for Zr at 31.5%. The Pd adsorption capacity was 0.228 mmol/g under the optimal conditions of 1.0 M HNO3 and a contact time of 30 min at 298 K. The experimental data fit the Langmuir model well, reflecting the monolayer uptake mechanism. Thermodynamic parameters ΔH°, ΔG°, and ΔS° and valuable chemical engineering data of Pd adsorption were obtained. It is promising to apply BOTZX in the simultaneous removal of Pd a...

2D-3D transformation of palladium and gold nanoparticles on functionalized Mo2C by multiscale simulation

Supported noble metal nanoparticles (NPs) are widely applied as heterogeneous catalysts in numerous reactions, in which the morphology of metal clusters is of crucial to the catalytic performance. In this study, the multiscale simulations concerned with the adsorption and morphological behavior of Pd, Au clusters and NPs on Mo2C, Mo2CO2 and Mo2CF2 have been performed systematically by density functional theory (DFT) and molecular dynamics (MD). There is an obvious morphological tendency of two-dimension (2D) to three-dimension (3D) for supported Pdn/Aun (n = 4–6) clusters from bare to O, F-terminated Mo2C. The electronic properties analysis shows that more charge transfer occurred on clusters leads to the stronger interaction between clusters and Mo2C MXene. The plots of projected density of states (PDOS) describe that the O, F groups weaken the strong interaction between clusters and bare Mo2C, showing that the nature of the change of morphology is the modification of d states of Pd, Au NPs by the introduction of O, F groups. The MD simulations of large supported Pdn/Aun NPs on bare and functionalized Mo2C are corresponded to the 2D-3D growth of DFT result, which shows that for metal NPs, the average coordination number as well as the interaction of Pd/Au NPs and support varies with the order of bare-O-F. Based on the multiscale simulations, the morphology ranges from Pd/Au clusters to NPs have been governed efficiently by surface groups, which may enlighten the design of metal-supported catalysts.

Effect of Ru, Rh, Mo, and Pd Adsorption on the Electronic and Optical Properties of Anatase TiO₂(101): A DFT Investigation.

Adsorbed metal atoms and metal doping onto TiO2 can effectively enhance the optical and photocatalytic activity of photocatalytic efficiency of titanium dioxide (TiO2), favoring the extension of its optical absorption spectrum and the efficiency of hydrogen generation. To investigate the possible mechanism causing potential improvement of photocatalytic activity, the electronic and optical properties of the anatase TiO2(101) plane with different adsorbed metal atom have been theoretically calculated through density functional theory (DFT) method. Adsorption of Pd and Ru atoms increases the delocalization of the density of states, with an impurity state near the Fermi level. Moreover, the investigated adsorbed metal atoms (Mo, Pd, Ru, Rh) narrow the band gap of anatase TiO2, thus enhancing the probability of photoactivation by visible light. The orbital hybridization of the d orbit from the adsorbed metal atom and the p orbit from the O of the defect site increases the Schottky barrier of the electronic structure.

Role of EDTA on the Pd(II) adsorption characteristics of chitosan cross-linked 3-amino-1,2,4-triazole-5-thiol derivative from synthetic electroless plating solutions.

This article targets the efficacy of chitosan cross-linked 3-Amino-1,2,4-triazole-5-thiol derivative for the recovery of Pd from synthetic electroless plating solutions (ELP) whose solution chemistry complexity is brought forward with ethylenediaminetetraacetic acid (EDTA), ammonium hydroxide (NH4OH), and surfactant (cetyl trimethyl ammonium bromide (CTAB)). Batch adsorption characteristics of the resin were investigated in the parametric range of 2-10 pH, 0.2-2 g L-1 adsorbent dosage, 5-1080 min contact time, 50-300 mg L-1 Pd concentration and 25-60 °C operating temperature. Equilibrium, kinetic and thermodynamic model fitness studies were also considered. Pd(II) adsorption characteristics were determined using NaOH, KOH and HCl solutions with variant eluent concentrations (0.1-2 N). The solution chemistry complexity has been evaluated to have profound impact in detrimentally influencing Pd sorption characteristics of the CH-AZ resin. The resin has been characterized to be highly effective for Pd removal from synthetic ELP solutions but with moderate efficacy towards the noble metal recovery and reuse.