Adsorption Of Platinum Research Articles

Nitrogen-rich sulfur-containing heterocyclic adsorbents for effective selective adsorption of Au(III)/Pd(II)/Pt(IV)

Recovering precious metals from secondary resources has elicited considerable attention, and exploring an efficient adsorbent is a challenge. In this work, we have specifically tailored three highly effective adsorbents (THDA@PEI, DCTA@PEI and DCTD@PEI) by crosslinking PEI with sulfur-containing heterocyclic cross-linking agents (2,5-thiophenedicarboxaldehyde, 2,4-dichlorothiazole and 3,4-dichloro-1,2,5-thiadiazole) for recovery of Au(III), Pd(II), and Pt(IV). These agents are distinguished by a range of nitrogen atom counts that extend from zero to two, offering a foundation for exploring the correlation between their molecular structure and adsorption performance. THDA@PEI, DCTA@PEI, and DCTD@PEI exhibit remarkable adsorption capacities for Au(III), Pd(II), and Pt(IV), with values reaching up to 2169, 2240, and 2536 mg/g for Au(III), 771, 886, and 846 mg/g for Pd(II), and 832, 1021, and 887 mg/g for Pt(IV), respectively. Among the three materials, DCTD@PEI stands out with a broader pH applicability range for both gold (pH 2 to 9) and platinum (pH 1 to 11) adsorption and exhibits a more rapid adsorption rate for Au and Pd. The adsorption processes of the three adsorbents on precious metals are spontaneous and entropy-increasing processes. Increasing the adsorption temperature could improve the adsorption performance of the three adsorbents, except for Pd adsorption by DCTD@PEI. All of the three adsorbents exhibit good selectivity and reusability for Au, Pd, and Pt, with DCTA@PEI being the most outstanding. It is observed that an increase in nitrogen content in the adsorbents correlates positively with the improvement of key performance indicators, including a wider pH range, higher adsorption capacity, faster kinetics, better selectivity, and enhanced reusability, while the substituent positions of crosslinking agents also have a strong impact on the adsorption performance, especially for Pd and Pt.

Enhanced pH Sensing Capability by Platinum Adsorption Onto Titanium Dioxide Nanorods

Enhanced pH Sensing Capability by Platinum Adsorption Onto Titanium Dioxide Nanorods

Effect of spacer length between N atoms of linear alkyl triamines on adsorption of anionic platinum(IV) ions

In this study, the effect of carbon chain length between N atoms in linear alkyl triamines on the adsorption of anionic platinum ions was studied. For this purpose, bis(3-aminopropyl)amine (BAPA-SG) and diethylenetriamine (DETA-SG) groups were covalently bonded to the silica gel surface. The modified silica gels were characterized through C, H, N elemental analyses and FTIR spectroscopy before being utilized for adsorption and preconcentration Pt(IV) ions from aqueous solutions. Various factors influencing the batch adsorption of Pt(IV) ions with BAPA-SG and DETA-SG, such as nitric acid, chloride, initial Pt(IV) concentration, and contact time, were investigated. The adsorption of Pt(IV) ions was most efficient in the solutions containing 0.1 M hydronium and 0.1 M chloride ions. The adsorbed amount of Pt(IV) increased with an increase in the initial concentration of Pt(IV). The adsorption of Pt(IV) ions with BAPA-SG and DETA-SG reached equilibrium in 2 and 4 h, respectively. The kinetics of Pt(IV) adsorption on both modified silica gels were found to be compatible with the Pseudo-second-order kinetic model. Langmuir isotherm accurately described the adsorption Pt(IV) ions with BAPA-SG and DETA-SG, with maximum monolayer adsorption capacities of 158.7 and 227.3 mg/g, respectively. In the column solid phase extraction studies, Pt(IV) ions could be quantitatively recovered from 500 mL sample solutions using both modified silica gels by eluting with acidic thiourea solutions. The recovery of Pt(IV) by DETA-SG from chloride-containing solutions was more effective than with BAPA-SG. As a result, it was concluded that diethylenetriamine-bonded silica gel could adsorb Pt(IV) ions more effectively than bis(3-aminopropyl)amine bonded silica gel.

Synthesis of Catalytic Microswimmers Based on Anisotropic Platinum Sorption on Melamine Barbiturate Supramolecular Structures

Herein, a straightforward synthesis approach for the formation of anisotropic microswimmers is proposed as an alternative to a top–down fabrication for asymmetric artificial swimmers. Melamine barbiturate (MBA)–self‐assembled supramolecular crystals are utilized as an asymmetric matrix for selective chemical platinum deposition. Surface functional groups of prevalent crystallographic planes for platinum sorption are presented by acidic sites of the assembly. The formed platinum catalytic layer is separated from the bulk MBA and investigated using X‐Ray photoelectron spectroscopy and scanning electron microscope energy‐dispersive X‐Ray spectroscopy analysis. Both methods confirm platinum adsorption and reduction of platinum ions during the deposition process. The MBA asymmetric swimmers show directional motion in a fuel environment, proved by the mean‐squared displacement study. Previously reported pH‐dependency and encapsulation capacity of MBA opens wide opportunities for functional materials formation.

Well entrapped platinum-iron nanoparticles on three-dimensional nitrogen-doped ordered mesoporous carbon as highly efficient and durable catalyst for oxygen reduction and zinc-air battery

The high-performance and durable oxygen reduction reaction (ORR) catalyst on air cathode is a key component in assembly of Zn-air batteries. Herein, three-dimensional N-doped ordered mesoporous carbon (3D N-OMC) was first prepared with silica as a template via pyrolysis with assistance of dicyandiamide as a N-doping agent, combined by full adsorption of platinum (II) acetylacetonate (Pt(acac)2) and iron (II) phthalocyanine (FePc) via π-π interactions. After further pyrolysis of the resulting mixture, many PtFe nanoparticles were efficiently incorporated in 3D N-OMC (termed as PtFe@3D N-OMC for simplicity). Control experiments were certificated the important role of the pyrolysis temperature played in this synthesis. The resultant composite synergistically combines advantages of hierarchically accessible surfaces, highly open structure, and well-dispersed PtFe particles, which endow the PtFe@3D N-OMC with onset and half-wave potentials of 0.98 and 0.86 V in alkaline media, respectively, showing appealing catalytic activity for the ORR. Most significantly, the PtFe@3D N-OMC based Zn-air battery has a high power density of 80.57 mW cm−2 and long-term durability (220 h, 660 cycles). This work opens a new avenue for design of high-efficiency and durable ORR electrocatalysts in energy conversion and storage systems.

Atomic-Scale Studies of Overlapping Grain Boundaries between Parallel and Quasi-Parallel Grains in Low-Symmetry Monolayer ReS2

Summary Grain boundaries (GBs) are significant microstructures that dominate properties of polycrystalline two-dimensional (2D) materials. Low-symmetry rhenium disulfide monolayers provide an ideal platform to investigate diverse configurations of GBs and their orientation-dependent characteristics. Here, we utilize the preferential deposition of platinum-based nanoparticles on grain edges to rapidly locate nanoscale-wide overlapping GBs during microscopic-scale observation. Atomic-resolution investigations by aberration-corrected annular dark-field scanning transmission electron microscopy reveal diverse overlapping GBs constructed by parallel grains with transversal displacement. They prefer to align along several primary lattice directions with different interlayer atomic registries. Calculations show that the electronic band structures of overlapping GBs are strongly direction dependent, suggesting their potential in tunable electronic and photonic devices. Incommensurate overlapping GBs formed by quasi-parallel grains with ultrasmall twist angles are also observed. These results unveil the rich polymorphism of GBs and new opportunities to tailor properties of anisotropic 2D materials via GB engineering.

Selective adsorption of palladium and platinum from secondary wastewater using Escherichia coli BL21 and Providencia vermicola

It is important to recover precious metals from secondary wastewater because of their low crustal abundance. The selective adsorption of palladium (Pd) and platinum (Pt) ions from secondary wastewater, which contains a large amount aluminium and sodium ions, was investigated using Escherichia coli BL21 (BL21), genetically modified E. coli BL21 (EC20) and Providencia vermicola (P. V.). The results demonstrated that P.V., BL21 and EC20 cells took 95.9%, 88.2% and 97.5% of Pd ions, and 64.8%, 93.2% and 100% of Pt ions form industrial wastewater, respectively. All three bacterial biomass could be reused for Pd adsorption with a second adsorption efficiency of > 85%, specifically, the EC20 cells could absorb 93.8% of Pd ions from wastewater. SEM-EDS and XPS analyses confirmed the occurrence of Pd and Pt on the surface of wastewater-absorbed biomass. The shift in FTIR spectrum implied that functional groups, such as hydroxyl, amino, carboxyl and phosphate groups, were involved in wastewater adsorption.

Enhancement of platinum biosorption by surface-displaying EC20 on Escherichia coli

To increase the platinum adsorption capacity of Escherichia coli (E. coli) biomass, we fused EC20 protein to the E. coli cell surface using an InaKN-based display system, which is the N-terminal region of ice nucleation protein that can be employed as a cell surface display motif. The media and culture conditions were optimized for EC20 (a phytochelatin analogue with 20 repeating units of glutamate and cysteine) expression and Pt (IV) biosorption. Furthermore, the adsorption process was elucidated from aspect of adsorption kinetics and equilibrium, and the characterization of blank and Pt-loaded cells were analyzed using SEM, AFM, TEM, FT-IR and XPS. Our study demonstrated that E. coli strain, which had InaKN-EC20 protein expressed on the cell surface, showed a great enhancement in Pt (IV) adsorption under optimized condition when comparing with that of original E. coli strain. The SEM-EDX analysis revealed that the cellular morphology has been changed in Pt-loaded cells, and the weight percent of platinum in the surface of E.coli increased substantially after displaying EC20 protein. Furthermore, intracellular platinum accumulation was detected in Pt-loaded EC20 cells since a clear peak of platinum exhibited, implying that cytoplasmic EC20 protein might also contribute to platinum accumulation. FTIR analysis revealed that the predominant functional groups in platinum adsorption were amine, carboxyl and phosphate groups.

A Hybrid Adsorbent Based on 4-Vinylpyridine‒2-Hydroxyethylmethacrylate Copolymer and Organosilicon Thiocarbamide

The adsorption of platinum(IV) in hydrochloric acid solutions of a composite based on N,N-bis(3-triethoxysilylpropyl)thiourea and 4-vinylpyridine‒2-hydroxyethylmethacrylate copolymer is studied. The value of the static adsorption capacity of the composite for platinum(IV) is found to be 215 mg/g. To describe the nature of the adsorption, Langmuir, Freundlich, and Dubinin–Radushkevich models are used. The adsorption kinetics is estimated using Boyd–Adamson models of pseudo-first and pseudo-second order and the Elovich equation.

Platinum Adsorption and Diffusion on Two-Dimensional Gallium Nitride

In this study, we examined the adsorption and diffusion of platinum (Pt) adatom on two-dimensional hexagonal gallium nitride (h-GaN), by using first-principles plane-wave calculations. Two different levels of platinum coverage ratio (θ=1/8 and θ=1/32) were considered and the changes in the electronic structure for high-level platinum coverage ratio (θ=1/8) were examined. Low-level coverage ratio (θ=1/32) is used to calculate the diffusion barrier energy of Pt adatom on GaN monolayer. Our theoretical calculations have shown that Pt atom strongly binds on the top of nitrogen atoms in GaN monolayer and high energy is required for its diffusion. While GaN monolayer has 2.1 eV indirect band gap (Γ→K), this band gap reduces to 1.3 eV with Pt adsorption. These results may lead to further investigations on forming Pt nanoparticles or Pt coating on GaN sheet.

Electrostatic Adsorption of Platinum onto Carbon Nanotubes and Nanofibers for Nanoparticle Synthesis

Strong Electrostatic Adsorption (SEA) has been demonstrated as a simple, scientific method to prepare well dispersed Pt nanoparticles over typical forms of carbon: activated, black, and graphitic carbons. Many varieties of specialty carbons have been invented in the last few decades including multi-walled nanotubes, nanofibers, graphene nanoplatelets, etc. In this work, we explore whether SEA can be applied to these specialty carbons for the synthesis of Pt nanoparticles. Over a number of oxidized and unoxidized multiwalled nanotubes and nanofibers, the point of zero charge (PZC) was measured and the uptake of anionic Pt complexes (Pt hexachloride, [PtCl6]2−, and cationic Pt complexes (platinum tetraammine, [Pt(NH3)4]2+) as functions of final pH were surveyed. Pt nanoparticles on the various supports were synthesized at the optimal pH and were characterized by x-ray diffraction (XRD) and scanning transmission electron microscopy (STEM). The specialty carbons displayed volcano-shaped uptake curves typical of electrostatic adsorption for both Pt anions at low pH and Pt cations at high pH. However, the regimes of uptake often did not correspond to the measured PZC, probably due to surface impurities from the carbon manufacturing process. This renders the measured PZC of these specialty carbons unreliable for predicting anion and cation uptake. On the other hand, the anion and cation uptake curves provide an “effective” PZC and do indicate the optimal pH for the synthesis of ultrasmall nanoparticle synthesis. High resolution STEM imaging also showed that with SEA it is possible to disperse nanoparticles on the surface as well as the inner walls of the specialty carbons.

Adsorption of platinum(IV) onto composites based on silicon dioxide and vinyl acetate/1-vinylimidazole and vinyl acetate/4-vinylpyridine copolymers

Composite materials are synthesized using the sol–gel method involving tetraethoxysilane and vinyl acetate/1-vinylimidazole and vinyl acetate/4-vinylpyridine copolymers, and their sorption capacity with respect to platinum(IV) ions is studied. The composites exhibit the highest sorption activity at 338 K in 1 M HCl solution (sorption capacity with respect to Pt(IV) varies from 180 to 249 mg g–1). The interaction between platinum(IV) and the surface of the sorption material is a result of the chemisorption process. The Langmuir, Freundlich, and Dubinin–Radushkevich models are used to describe the nature of adsorption.

Adsorption of platinum(IV) from an aqueous solution with magnetic cellulose functionalized with thiol and amine as a nano‐active adsorbent

ABSTRACTIn this study, magnetic cellulose was prepared and then functionalized by the grafting of glycidyl methacrylate and reaction with thiourea/amine [to produce grafted magnetic cellulose with thiol/amine (GMC–N/S)]. Thus, GMC–N/S as a nano‐active adsorbent was investigated for the adsorption of Pt(IV) in a batch system. A response surface methodology was used to study the effects of four independent variables [Pt(IV) concentration, temperature, pH of the solution, and adsorbent dose] and to optimize the process conditions for the maximum adsorption of platinum(IV) from aqueous solutions by GMC–N/S. A high coefficient of determination (R2 = 98.46) implied the adsorption of Pt(IV) onto the adsorbent in a valid manner, and only 1.54% of the total variable was not explained by the model. The equilibrium adsorption data were fitted to the Langmuir isotherm. The maximum monolayer adsorption capacity of the adsorbent (GMC–N/S) for Pt(IV) was determined to be 40.48 mg/g. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45361.

Platinum surface complexes as precursors for H2–O2 recombination catalysts

In this work, the adsorption of platinum (II, IV) chloride complexes from acidic solutions on silica gel modified with quaternary ammonium salts (QAS) was studied. The uptake of the platinum chloride complexes is caused by the formation of ionic (QAS+)2[PtCl x]2− ( x = 4, 6) associates on the surface of silica gel. The isotherms of adsorption are fitted by the Langmuir model. The maximum capacity for [PtCl4]2− and [PtCl6]2− is 0.99 and 1.13 mmol/g, correspondingly. The respective adsorption constants KL = 6.8 and 10 × 105 l/mol prove the high affinity of the adsorbates to the QAS-modified surface. Platinum metal nanoparticles supported on the surface of the silica gel were prepared by reducing the adsorbed platinum (II, IV) complexes. Such nanoparticles functioning at the moderate temperature regime have demonstrated a reasonable catalytic activity for the hydrogen and oxygen recombination, and an excellent stability over 35 cycles of the reaction.

Platinum adsorption onto graphene and oxidized graphene: A quantum mechanics study

Density functional theory based on first-principle calculations was used to examine platinum-supported oxidized graphene as a beneficial nanomaterial in terms of its catalytic activity and utility for contaminant removal and disinfecting polluted solutions in both domestic and industrial applications. The first step was to select the most appropriate available computing package to apply the supercell technique, which would provide a better representation of a large and real graphene slab. Using OpenMX was less time-consuming after we enforced a basis set for valence electrons to avoid an all-electron calculation, and this had very slight and negligible effect on the accuracy of the calculations. The OpenMX software was selected to perform forward steps of investigating changes in the properties such as adsorption energy and ground state structure of the complexes made by the adsorption of a platinum atom on the surface of pristine graphene (Pt/PG) and oxidized graphene (Pt/OG), which had the lowest adsorption energy of −5.28 eV. Moreover, we examined the effect of Pt atom adsorption on the surface and between two layers of graphene. Our results show that, there was no specific change observed in mentioned properties of Pt atom adsorption on bilayer graphene in comparison with single layer.

Adsorption of platinum(IV) by a composite based on silicon dioxide and copolymer of 4-vinylpyridine and 2-hydroxyethylmethacrylate

The adsorption of platinum(IV) solutions by a composite based on silicon dioxide and copolymer of 4-vinylpyridine and 2-hydroxyethylmetacrylate in hydrochloric acid solutions has been studied. The maximum efficiency of extraction of platinum(IV) ions has been detected in a solution of HCl with a concentration of 1 mol L–1 at a temperature of 338 K (sorption capacity equal to 188 mg g–1). The interaction of platinum (IV) with the surface of the composite is a result of chemisorption. The models of Langmuir, Freundlich, and Dubinin–Radushkevich have been used to describe the nature of adsorption. Adsorption kinetics was assessed using the models of Boyd–Adamson, pseudofirst and pseudosecond orders, and Elovich.

Platinum adsorption on ceria: A comparative theoretical study of different surfaces

A comparative study, based on the density functional theory, on the adsorption of single Pt atoms on the CeO2(111), (110), and (100) surfaces has been performed. According to the calculated adsorption energies, it is suggested that the deposited Pt atoms on the CeO2(111) surface are easy to aggregate and form nanoparticles compared with those on the CeO2(110) and (100) surfaces. Further, the interaction strength between Pt and the three CeO2 surfaces follows the order of (100)>(110)>(111). It is also found that there is a correlation between the formal oxidation state of the adsorbed Pt and its coordination number with respect to O. The Pt atom coordinated by one O atom on the CeO2 surfaces is only slightly charged and almost neutral, and that coordinately by four O atoms exclusively has the formal oxidation state of Pt2+. The possible reasons for these findings have been discussed. And the present theoretical results have been compared with the available experimental reports. It is expected that our studies will give useful insights into the shape-dependent interaction between Pt with CeO2 nanocrystals and the shape-dependent oxidation state of the deposited Pt.

A Study on the Utilization of Magnetite for the Recovery of Platinum Group Metals from Chloride Solution

ABSTRACTThe recovery of platinum group metals (PGMs) from chloride solution using magnetite was investigated. The adsorption of platinum, palladium, and rhodium in chloride medium onto synthetic magnetite powders were studied at different pH conditions, contact time, sodium chloride concentrations, and initial Pt, Rh, and Pd concentrations. Platinum and palladium uptake by magnetite was at a maximum at pH 6–7, and pH 3–4 for rhodium after 24 h with 0.1 mol/dm3 sodium chloride at an initial PGM concentration of 0.05 mol/m3. A sorption mechanism for PGMs was discussed based on the results.

Dispersive Plasmon Damping in Single Gold Nanorods by Platinum Adsorbates.

Surface modifications of plasmonic nanoparticles with metal adsorbates are essential in applications such as plasmonic sensing, plasmon-enhanced photocatalysis, etc., where spectral broadening is usually observed. A single particle study is presented on plasmon damping by adsorption of platinum (Pt) clusters. Single particle dark-field spectroscopy is employed to measure exactly the same gold nanorod before and after the Pt adsorption. The Pt-induced plasmon damping in terms of linewidth increase is found dependent on the resonance wavelength of the measured nanorod, which is dispersive in nature. The measured dispersion generally matches the theoretical prediction, and it basically exhibits a gradual increase with decreasing resonance energy. This increase can be attributed to the fact that the nanorod as a better resonator is more susceptible to the Pt adsorption than the spherical particles. Moreover, simulated results based on discrete dipole approximation method further indicate that the damping is mainly contributed from the adsorbates on the ends of the nanorod and independent on the type of the metal adsorbed. Knowledge and insights gained in this study can be very important for the design and fabrication of plasmonic heterostructures as functional nanomaterials.

Adsorption of Platinum (IV) by Sorbents Based on Hybrid Composites

We have investigated the adsorption of platinum(IV) ions by sorbents based on sol—gel synthesis products with the participation of vinylglycidyl ether ethyleneglycol copolymers with vinylchloride and organisilicon monomers: N,N′-bis(3-triethoxysilylpropyl)thiocarbamide and 2-([triethoxysilylpropyl] amino)pyridine. We have shown that the interaction of platinum(IV) with the composite surface is a result of both physical adsorption and chemical adsorption. We have used the Langmuir, Freundlich, and Dubinin—Radushkevitch models to describe the nature of adsorption. Boyd—Adams, pseudo-first and pseudo-second-degree, and Elovitch models were used to evaluate adsorption kinetics