Sodium Formate Research Articles

From formic acid to single-cell protein: genome-scale revealing the metabolic network of Paracoccus communis MA5

With the increase in population growth and environmental pollution, the daily protein supply is facing great challenges. Single-cell protein (SCP) produced by microorganism fermentation is a good alternative for substituting plant- and animal-derived proteins. In this study, Paracoccus communis MA5 isolated from soil previously demonstrated an excellent ability to synthesize SCP directly from sodium formate. To investigate the central metabolic network of formic acid assimilation and protein synthesis, genome-scale analyses were performed. Genomic analysis showed that complete tetrahydrofolate cycle-, serine cycle-, glycolytic pathway-, tricarboxylic acid (TCA) cycle- and nitrogen metabolism-relevant genes were annotated in the genome. These pathways play key roles in the conversion of formic acid into proteins. Transcriptional analysis showed that sodium formate stress could stimulate the metabolic pathway in response to environmental stress, but weaken the sulfur metabolic pathway to inhibit amino acid synthesis, resulting in a decrease in protein content (30% vs 44%). However, under culture conditions with ammonium sulfate, metabolic pathways associated with protein synthesis were accelerated, causing an increase in protein content (53% vs 44%); while the tetrahydrofolate cycle associated with formic acid assimilation was inhibited, causing a 62.5% decrease in growth rate (OD600: 0.21 vs 0.56). These results provide evidence of protein synthesis from sodium formate in strain MA5 at the gene level and lay a theoretical foundation for the optimization of fermentation systems using formic acid as a carbon source.Graphical

Visible Light Reductive Photocatalysis of Azo-Dyes with n-n Junctions Based on Chemically Deposited CdS.

New composite photocatalysts have been obtained by chemical bath deposition of CdS on top of either nanostructured crystalline ZrO2 or TiO2 films previously deposited on conductive glass FTO. Their morphological, photoelectrochemical and photochemical properties have been investigated and compared. Time resolved spectroscopic, techniques show that in FTO/TiO2/CdS films the radiative recombination of charges, separated by visible illumination of CdS, is faster than in FTO/ZrO2/CdS, evidencing that carrier dynamics in the two systems is different. Photoelectrochemical investigation evidence a suppression of electron collection in ZrO2/CdS network, whereas electron injection from CdS to TiO2 is very efficient since trap states of TiO2 act as a reservoir for long lived electrons storage. This ability of FTO/TiO2/CdS films is used in the reductive cleavage of N=N bonds of some azo-dyes by visible light irradiation, with formation and accumulation of reduced aminic intermediates, identified by ESI-MS analysis. Needed protons are provided by sodium formate, a good hole scavenger that leaves no residue upon oxidation. FTO/TiO2/CdS has an approximately 100 meV driving force larger than FTO/ZrO2/CdS under illumination for azo-dye reduction and it is always about 10% more active than the seconds. The films showed very high stability and recyclability, ease of handling and recovering.

Silver-Cobalt bimetallic nanoparticles to the generation of hydrogen from formic acid decomposition

The fabrication of cost effective heterogeneous catalysts for the release of hydrogen from hydrogen storage materials is the key technological challenge to the fuel-cell based hydrogen economy. Ag-Co bimetallic NPs were fabricated by using sodium dodecyl sulphate (SDS) and sodium borohydride as stabilizing and reducing agents, respectively. Catalytic activity of SDS-Ag-Co was higher than that of SDS free Ag-Co and monometallic (Ag and Co) due to the electron interactions and synergistic effect between the Ag and Co. Ag 10 -Co 90 exhibited the superior catalytic activity, with rate constant of 5.2 × 10 −4 s −1 at 303 K, activation energy of 46 kJ/mol, activation enthalpy of 44 kJ/mol, activation entropy of −165 J/K/mol, and turn over frequency of 240 h −1 . The hydrogen generation rate increased and decreased with in increasing temperature, molar concentration of formic acid, presence of sodium formate, and pH, respectively. The kinetic rate equation can be stated as: rate = -d[formic acid]/dt = k obs [formic acid] 0.99 [Ag 50 Co 50 ] 0.98 , k obs = 2.48 × 10 7 exp (−5637.96/RT).

In situ hydrogenation of phenol using sodium formate in an aqueous medium on unmodified palladium catalysts supported on KIT-5: Investigation of calcination temperature effect

In this research, in situ hydrogenation of phenol to cyclohexanone and cyclohexanol mixture (KA oil) in aqueous medium using sodium formate as the hydrogen source is studied by using Pd catalysts supported on mesoporous KIT-5. The effect of calcination temprature of catalysts as well as reaction temperature, time, catalyst types, the amount of initial phenol and sodium formate, which are the most effective factors for phenol conversion, were investigated and the optimum values are reported. The Pd10%@KIT-5/350 catalyst (calcined at 350°C) exhibited as the most effective catalyst. Using this catalyst, the best results were gained at 40°C and a reaction time of 6 h, the optimal ratio of phenol: catalyst 0.1:0.05 with 0.5 g sodium formate. Under these conditions, 99% phenol conversion was obtained. Pd10%@KIT-5/350 as the most effective catalyst was successfully regenerated by centrifugation and filtration after reaction and reused in four consecutive cycles. The results showed that the calcination temperature in the preparation of Pd@KIT-5 catalysts has an important role in the hydrogenation reaction of phenol. The studies in this research showed that the higher the calcination temperature, the lower the percentage of phenol conversion, but the selectivity of the catalyst for the production of cyclohexanone increases.

Ferrocene-Doped Polystyrene Nanoenzyme and DNAzyme Cocatalytic SERS Quantitative Assay of Ultratrace Pb2.

A new, stable and high-catalytic activity ferrocene-doped polystyrene nanosphere (PNFer) sol was prepared by the hydrogel procedure and characterized by electron microscopy and molecular spectroscopy. Results show that the nanosol exhibits excellent catalysis of the new indicator nanoreaction between AgNO3 and sodium formate to generate nanosilver with strong surface-enhanced Raman scattering (SERS), resonance Rayleigh scattering (RRS) and surface plasmon resonance absorption (Abs) trimode molecular spectral signals. This new nanocatalytic amplification trimode indicator reaction was coupled with the G-quadruplex DNAzyme catalytic amplification of Pb2+ aptamer to fabricate a new SERS quantitative/RRS/Abs assay platform for the determination of ultratrace amounts of Pb2+. The Pb2+ content in water samples was analyzed with satisfactory results.

Effectiveness of cellulose polyanionic-based polymers on the measurement of rheological properties of water-based drilling fluids in high-pressure high-temperature fractured shale reservoirs

High-pressure, high-temperature fractured shale reservoirs are types of unconventional reservoirs that need proper drilling operations for adequate efficiency. Proper measurement of drilling fluid’s rheological properties is of importance for drilling operations that may increase the penetration rate on the one hand with proper design. Therefore, the success of drilling operations strongly depends on the proper design of drilling fluids. In this paper, we experimentally investigated the effect of potassium and sodium formate fluid on the rheological properties of drilling fluid for fractured shale core samples. The yield point and apparent viscosity for muds consisted of cellulose polyanionic and cellulose polyanionic-ultralow polymers higher than base muds. It indicates the effect of formate salts in increasing thermal stability. In addition, in polymer-based muds, more amounts of formate salts have been used, indicating the low fluid loss volume. Consequently, the shale recovery rate for potassium formate fluids is higher than sodium formate fluid.

High-Yield Synthesis of Enantiopure 1,2-Amino Alcohols from l-Phenylalanine via Linear and Divergent Enzymatic Cascades.

Enantiomerically pure 1,2-amino alcohols are important compounds due to their biological activities and wide applications in chemical synthesis. In this work, we present two multienzyme pathways for the conversion of l-phenylalanine into either 2-phenylglycinol or phenylethanolamine in the enantiomerically pure form. Both pathways start with the two-pot sequential four-step conversion of l-phenylalanine into styrene via subsequent deamination, decarboxylation, enantioselective epoxidation, and enantioselective hydrolysis. For instance, after optimization, the multienzyme process could convert 507 mg of l-phenylalanine into (R)-1-phenyl-1,2-diol in an overall isolated yield of 75% and >99% ee. The opposite enantiomer, (S)-1-phenyl-1,2-diol, was also obtained in a 70% yield and 98–99% ee following the same approach. At this stage, two divergent routes were developed to convert the chiral diols into either 2-phenylglycinol or phenylethanolamine. The former route consisted of a one-pot concurrent interconnected two-step cascade in which the diol intermediate was oxidized to 2-hydroxy-acetophenone by an alcohol dehydrogenase and then aminated by a transaminase to give enantiomerically pure 2-phenylglycinol. Notably, the addition of an alanine dehydrogenase enabled the connection of the two steps and made the overall process redox-self-sufficient. Thus, (S)-phenylglycinol was isolated in an 81% yield and >99.4% ee starting from ca. 100 mg of the diol intermediate. The second route consisted of a one-pot concurrent two-step cascade in which the oxidative and reductive steps were not interconnected. In this case, the diol intermediate was oxidized to either (S)- or (R)-2-hydroxy-2-phenylacetaldehyde by an alcohol oxidase and then aminated by an amine dehydrogenase to give the enantiomerically pure phenylethanolamine. The addition of a formate dehydrogenase and sodium formate was required to provide the reducing equivalents for the reductive amination step. Thus, (R)-phenylethanolamine was isolated in a 92% yield and >99.9% ee starting from ca. 100 mg of the diol intermediate. In summary, l-phenylalanine was converted into enantiomerically pure 2-phenylglycinol and phenylethanolamine in overall yields of 61% and 69%, respectively. This work exemplifies how linear and divergent enzyme cascades can enable the synthesis of high-value chiral molecules such as amino alcohols from a renewable material such as l-phenylalanine with high atom economy and improved sustainability.

Comparison of decontamination efficacy of two electrolyte cleaning methods to diode laser, plasma, and air-abrasive devices.

To compare the in vitro decontamination efficacy of two electrolytic cleaning methods to diode laser, plasma, and air-abrasive devices. Sixty sandblasted large-grit acid-etched (SLA) implants were incubated with 2ml of human saliva and Tryptic Soy Broth solution under continuous shaking for 14days. Implants were then randomly assigned to one untreated control group (n = 10) and 5 different decontamination modalities: air-abrasive powder (n = 10), diode laser (n = 10), plasma cleaning (n = 10), and two electrolytic test protocols using either potassium iodide (KI) (n = 10) or sodium formate (CHNaO2) (n = 10) solution. Implants were stained for dead and alive bacteria in two standardized measurement areas, observed at fluorescent microscope, and analyzed for color intensity. All disinfecting treatment modalities significantly reduced the stained area compared to the untreated control group for both measurement areas (p < 0.001). Among test interventions, electrolytic KI and CHNaO2 treatments were equally effective, and each one significantly reduced the stained area compared to any other treatment modality (p < 0.001). Efficacy of electrolytic protocols was not affected by the angulation of examined surfaces [surface angulation 0° vs. 60° (staining %): electrolytic cleaning-KI 0.03 ± 0.04 vs. 0.09 ± 0.10; electrolytic cleaning-CHNaO2 0.01 ± 0.01 vs. 0.06 ± 0.08; (p > 0.05)], while air abrasion [surface angulation 0° vs. 60° (staining %): 2.66 ± 0.83 vs. 42.12 ± 3.46 (p < 0.001)] and plasma cleaning [surface angulation 0° vs. 60° (staining %): 33.25 ± 3.01 vs. 39.16 ± 3.15 (p < 0.001)] were. Within the limitations of the present in vitro study, electrolytic decontamination with KI and CHNaO2 was significantly more effective in reducing bacterial stained surface of rough titanium implants than air-abrasive powder, diode laser, and plasma cleaning, regardless of the accessibility of the contaminated implant location. Complete bacterial elimination (residual bacteria < 1%) was achieved only for the electrolytic cleaning approaches, irrespectively of the favorable or unfavorable access to implant surface.

Finely dispersed AgPd bimetallic nanoparticles on a polydopamine modified metal organic framework for diverse catalytic applications

An efficiently supported noble metal-based heterogeneous catalyst with ultrafine dispersion and small size for multifunctional catalysis and pollutant degradation is highly desirable. In this work, a polydopamine modified-MOF (MIL-125-NH2) template has been used to synthesize ultrafine silver-palladium (AgPd) bimetallic nanoparticles. The characterization results confirm the formation of well-dispersed ultrafine bimetallic nanoparticles with a narrow size distribution (2.2 ± 0.3 nm). The prepared catalyst exhibits excellent heterogeneous catalytic activity with high turnover frequency in batch and continuous nitrophenol reduction, aldehyde hydrogenation, formic acid dehydrogenation (in the presence of additive sodium formate), and Suzuki–Miyaura coupling reaction at ambient conditions. Moreover, its high stability makes it a durable catalyst system for multicycle use after recycling or in a continuous flow reactor. The rate of hydrogen production using AgPd@MIL-125-NH2-PDA is many orders of magnitude higher than that of uncoated and monometallic (Ag or Pd) nanoparticles on MOF. Additionally, density functional theory (DFT) calculations provide an insight mechanism for each FA dehydrogenation step and show that the bimetallic nanoparticle on PDA coated MOF has better selectivity towards FA dehydrogenation by following a lower energy path for hydrogen desorption. These findings highlight the advantages of rational template modification in synthesizing finer bimetallic nanoparticles, which can open up many new avenues for designing metal nanoparticle-MOF-based composite materials for a variety of potential applications.

Extracting high-purity hydrogen via sodium looping-based formic acid dehydrogenation

Formic acid (FA) has been considered as a prospective hydrogen carrier for its potentials to realize hydrogen storage, transportation, and in-situ supply under mild conditions. However, the application of FA dehydrogenation is limited by its unsatisfactory hydrogen concentration and carbon monoxide selectivity. Herein, a sodium looping-based (Na 2 CO 3 ↔NaHCO 3 ) formic acid dehydrogenation (SLFAD) system is proposed for high-purity hydrogen production with ultra-low CO generation via the Na 2 CO 3 ↔NaHCO 3 looping. The SLFAD system consists of three parts, which are FA dehydrogenation reactor (FADR), sorption-enhanced carbon oxide removal reactor (CORR), and sodium-based sorbent regeneration reactor (SSRR). Experimental results proved that no sodium formate and sodium oxalate was formed under NaHCO 3 reduction by H 2 . A comprehensive assessment of the system was carried out to preliminary verify the feasibility and optimize the operation parameters of the SLFAD system. Results indicated that a maximum hydrogen concentration of 97.905 vol%, a minimum CO concentration of 11.97 ppm, and a high hydrogen production rate of 0.99989 kmol H 2 h −1 can be obtained under the conditions of atmospheric pressure, FADR temperature at 80 °C, H 2 O/HCOOH = 1.2, CORR temperature at 80 °C, and Na 2 CO 3 /HCOOH = 1.0. • A sodium looping based formic acid dehydrogenation (SLFAD) concept was proposed. • A high hydrogen concentration of 97.90 vol% can be obtained at low temperatures. • Carbon monoxide concentration can be restricted to be 11.97 ppm via SLFAD process. • Sodium-based absorbent can be regenerated with the achievement of CO 2 capture.

Synthesis and gelation properties of HPMC-g-poly(AM/AA/APEG2400) quaternary copolymer

To improve the stability of the polymers applied to profile control in high-temperature and high-salinity reservoirs, a water-soluble graft-copolymer HPMC-g-poly(AM/AA/APEG2400) was synthesized from hydroxypropylmethylcellulose (HPMC), acrylamide (AM), acrylic acid (AA), and allyl polyoxyethylene ether (APEG2400) via free-radical copolymerization using potassium persulfate (KPS) as the initiator. The molecular weight (Mw) of HPMC-g-poly(AM/AA/APEG2400) was controlled by the addition of the chain-transfer agent, sodium formate (SF), to the polymerization medium and was measured by capillary viscometry. Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), proton nuclear magnetic resonance (1H NMR), and scanning electron microscopy (SEM) were performed to characterize the graft-copolymer. The rheological properties of the graft-copolymer were investigated at different salinities and temperatures. The graft-copolymer solution showed better salt resistance, temperature tolerance, and long-term thermal stability than partially hydrolyzed polyacrylamide (HPAM). In addition, hydrogels were prepared using the graft-copolymer with varying Mw (346 × 104–1319 × 104), a crosslinker (hexamethylenetetramine–resorcinol, (HMTA–RC)), and additives (citric acid, (CA), and ammonium phosphate monobasic, (MAP)), and the hydrogels exhibited adequate strength and tunable gelation time. The hydrogels prepared using the graft-copolymer with high Mw possessed excellent long-term stabilities with negligible syneresis at 45 °C after 130 d, for the same conditions, the syneresis of conventional hydrogels prepared by HPAM reached approximately 90%.

Ternary composite phase change materials (PCMs) towards low phase separation and supercooling: eutectic behaviors and application

Salt hydrates have been used as phase change materials (PCMs) for various types of Thermal Energy Storage (TES) especially for cold storage. In this project, a novel composite phase change material (PCM) consisted of mixed solution of inorganic salt and organic salt was developed and characterized. Firstly, the PCM solutions containing sodium formate, potassium chloride and water with various weight percentage were evaluated to understand their solidification temperature, melting temperature, the supercooling degree and the latent heat. Then a PCM with mass fractions at weight percentages of 22%/12%/66% with better performance was selected for further study to restrain the supercooling. Different gelling agents and nucleate agents were employed in this PCM. The results show that the addition of 0.6 wt% xanthan gum can effectively prevent the phase separation and leakage, while 0.6 wt% of nano-TiO2 is the best nucleating agent since the supercooling can be reduced to 2.6 °C, which is 67.9% lower than that of the original PCM without any nucleating agent. Finally, the novel PCM was tested for frozen food storage application, in which the food temperature could be maintained below -18 °C for over 10 hours in the insulated box. This indicated the suitability of developed PCM for frozen food storage and transportation.

Anoxic treatment for thiosulfate separation from formate containing dithionite industrial effluent and electrochemical sulfur recovery

The present work deals with utilization of formate present in the dithionite industrial effluent for thiosulfate separation and electrochemical sulfur recovery. In anoxic treatment, Pseudomonas aeruginosa and Proteus mirabilis were used for formate utilization and thiosulfate reduction. The organisms utilized sodium formate as a carbon source and thiosulfate as a terminal electron acceptor, it degraded the organic compounds fully present in the effluent. Thiosulfate got reduced to sulfide or hydrogen sulfide, where thiosulfate reduction was insignificant. Impact of iron surface on anoxic thiosulfate reduction was also investigated in the present study. An electrochemical two chambered membrane cell was used to recover sulfur from the biogenic sulfide electrolyte. Three different types of surface pattern (flattened, twisted and cylindrical) of Ti-TiO2/IrO2/RuO2 coated mesh anodes were used to comparing the sulfide to sulfur conversion process. Rotating cylindrical mesh electrode gave maximum sulfur recovery efficiency (96%) when compared to twisted (91%) and flattened (61%) electrodes. In this process, excess sodium hydroxide was also recovered at the catholyte during biogenic sulfide oxidation.

Modification of Palladium Nanocrystals with Single Atom Platinum via an Electrochemical Self-Catalysis Strategy for Efficient Formic Acid Electrooxidation.

Single atom alloys (SAA) have recently drawn increased attention due to their unique structure, high atomic utilization, and fascinating catalytic performance. However, their controllable synthesis still presents a challenge. This study proposes an electrochemical self-catalysis (ESC) strategy to synthesize Pd@Pt/C SAA catalysts, that is, depositing Pt atoms on Pd nanocrystals through in situ decomposition of sodium formate. The relationship between composition and structure of Pd@Pt/C is distinguished through a combination of electrochemical analysis, sphere-corrected scanning transmission electron microscopy, and X-ray adsorption spectra. That relationship evolved from SAA to a sea-island structure and even a core-shell structure with composition-controllable atomic ratios, highlighting the great diversity and convenience of this method in nanostructure construction. The Pd@Pt/C SAA catalyst showed excellent catalytic activity to formic acid oxidation with a peak current density of 5.2 A/mgmetal, which is about 18.6 times that of the commercial Pd/C. density functional theory calculations revealed that the enhanced activity was due to the "passivation" of Pd sites near the Pt single atoms, which attenuated the adsorption of CO. Based on electrochemical principles, this ESC strategy was also expanded to prepare a series of Pd-based SAA, including Pd-Au, Pd-Ir, and Pd-Bi.

Effect of Complexing Agent on The Morphology and Corrosion Effect of Cu-Sn-Zn Ternary Alloy via Electroplating

Copper-tin-zinc (Cu-Sn-Zn) ternary alloy coatings was successfully deposited from a less hazardous electrolyte containing copper (II) chloride, tin (II) chloride, zinc chloride, sodium hypophosphite and complexing agent. In this work, the impact of different complexing agent on morphology, chemical composition, current efficiency, microhardness, and corrosion rate were investigated by method of SEM equipped with EDX spectroscopy, weight gain measurements, XRD, Vickers microhardness test and potentiodynamic polarization measurement, respectively. It was discovered that, Cu-Sn-Zn alloys prepared using sodium formate shows the highest microhardness value. It is also can be concluded that, complexing agent have a significant impact on the appearance and the surface morphology of the Cu-Sn-Zn alloy electrodeposits.

Ligand effects in rhodium complexes for chemical NADH regeneration

AbstractVarious (pentamethylcyclopentadienyl)‐rhodium(III) complexes comprising aromatic bidentate ligands [(Cp*)Rh(L)Cl]+ (Cp* = pentamethylcyclopentadienyl, L = 2,2′‐bipyridine, 1,10‐phenanthroline, and their derivatives) were prepared to compare their reactivities of chemical cofactor regeneration. When the catalytic NADH regeneration was performed with sodium formate−, the reaction rates were compared with six Rh(III) complexes. The kinetics of the reactions including kinetic isotope effects are also studied in the chemical NADH regeneration. The Rh(III) complexes react with formate efficiently to afford the intermediates [(Cp*)Rh(L)(H)]+ and CO2. The electronic and steric effects of the ligands of the Rh complexes were observed on the reaction rates. The overall reaction rates of the NADH regeneration were also obtained using DCOO− in H2O. Such H/D exchange rates of [(Cp*)Rh(L)(H)]+ and the observation of a deuterium kinetic isotope provide valuable mechanistic insight into the catalytic NADH regeneration.

Sodium borohydride hydrolysis-mediated hydrogenation of carbon dioxide, towards a two-step production of formic acid

One of the levers to mitigate the amount of carbon dioxide (CO2) released into the atmosphere is to capture and use it as cheap, abundant, and safe carbon source, that is, as feedstock in order to produce valuable chemicals like formic acid (HCOOH) that is known to have the potential for high environmental impact reduction. It is in this context that we have developed a two-step process to produce HCOOH by hydrogenation of CO2 at ambient conditions while using sodium borohydride (NaBH4) in aqueous solution. Our process can be described as follows. In a first step, CO2 is bubbled in an aqueous solution of NaBH4; nickel-catalyzed hydrolysis of NaBH4 takes place and the reaction is accelerated in the presence of CO2, resulting in the formation of, among other products, sodium formate (NaHCOO) and a HCOO group containing borate B(OH)2(OOCH). In a second step, these products are dissolved in alkaline aqueous solution and heated at 130 °C; in such conditions, HCOOH is produced and recuperated as distillate, and a solid ‘residue’ consisting mainly of Na2CO3, NaHCOO and NaB(OH)4 is recovered. Our two-step process aiming at capturing and transforming CO2 has proven to be effective, importantly at ambient conditions. Our main results and the remaining challenges are reported and discussed herein.

Purification and concentration of formic acid from formic acid/gluconic acid mixtures by two successive steps of nanofiltration and reactive liquid-liquid extraction

A downstream process for the purification and concentration of formic acid (FA) from FA/gluconic acid (GA) mixtures, obtainable by a coupled biocatalytic reaction of CO2 reduction and glucose oxidation, has been developed. The process involved two technologies: (i) a first nanofiltration (NF) step to separate FA and GA, and (ii) a second reactive liquid-liquid extraction (RLLE) step to concentrate FA. The NF process, using a Synder NFX membrane, consisted of three NF steps separated into two divergent lines, named permeate and retentate pathways. The first NF was common for both pathways, resulting in a permeate strongly enriched in FA and depleted in GA, and a retentate with opposite characteristics. In the permeate pathway, this first permeate was subjected to a second NF to obtain a 99.6% pure FA permeate. In the retentate pathway, an additional NF step on the first retentate resulted in a concentrated 99.4% pure GA retentate. The final diluted FA permeate was concentrated by RLLE using tri-N-octylamine as extractant in n-octanol, and a final back-extraction with NaOH. The optimized RLLE process involved a 100-fold volume decrease and resulted in a final FA solution (as sodium formate) of 174.5 g/L, 78 times more concentrated than the feed.

Studies on the Formation of Catalytically Active PGM Nanoparticles from Model Solutions as a Basis for the Recycling of Spent Catalysts.

The paper presents basic studies on the precipitation of platinum, palladium, rhodium, and ruthenium nanoparticles from model acidic solutions using sodium borohydride, ascorbic acid, and sodium formate as reducing agents and polyvinylpyrrolidone as a stabilizing agent. The size of the obtained PGM particles after precipitation with NaBH4 solution does not exceed 55 nm. NaBH4 is an efficient reducer; the precipitation yields for Pt, Pd, Ru, Rh are 75, 90, 65 and 85%, respectively. By precipitation with ascorbic acid, it is possible to efficiently separate Pt, Rh, and Ru from Pd from the two-component mixtures. The obtained Pt, Pd, and Rh precipitates have the catalytic ability of the catalytic reaction of p-nitrophenol to p-aminophenol. The morphological characteristic of the PGM precipitates was analyzed by AFM, SEM-EDS, and TEM.

Molecular orientation of small carboxylates at the water–air interface

This work reports first phase resolved VSFG measurements on sodium formate and sodium acetate aqueous solutions. Both anions show a clear vibrational surface response and the net orientation of the carboxylate group pointing toward the solution.