Formaldehyde In Aqueous Solution Research Articles

Regeneration of bulk and silica-supported gallium oxide catalysts applied in the dehydrogenation of methanol to formaldehyde and hydrogen by reaction-oxygen regeneration cycles and oxygen pulses in the feed

The oxygen-free dehydrogenation of methanol to formaldehyde and hydrogen is a potential alternative to the established industrial oxidative dehydrogenation yielding aqueous formaldehyde solutions. Advantages are the production of anhydrous formaldehyde and of hydrogen as a valuable coupled product. However, fast deactivation of the catalyst occurs under the high-temperature reaction conditions mainly due to coking, which can be overcome by applying oxygen at a temperature high enough to allow fast oxidation of the carbon deposits but low enough to prevent the loss of Ga. From an engineering point of view, a stable reaction temperature in the catalyst bed and a high H2 yield have to be maintained, requiring that the catalyst enables methanol dehydrogenation, but not the oxidation of hydrogen to water. Thus, two modes of regeneration of GaOx-based catalysts were investigated using reaction − oxygen regeneration cycles and oxygen pulses in the feed. When using bulk Ga2O3 as catalyst and applying optimized reaction-regeneration cycles, a formaldehyde yield of 51 % and a hydrogen yield of 45 % at a stable methanol conversion of 65 % were achieved, whereas undiluted O2 pulsed into the feed every 30 s resulted in a continuous formaldehyde yield of 40 % and a hydrogen yield of 35 % at a stable methanol conversion of 59 % with water yields below 2 % and 4 %, respectively. The effects of the two operation modes on stability and product distribution are discussed in terms of the carbon removal rate from the surface, refilling of oxygen vacancies and parasitic reactions in the presence of oxygen. Specifically, the consumption of O2 did not lead to excessive water formation but preferentially effected the oxidation of the carbon deposits to CO and CO2.

Morphometric study of ostrich kidneys Struthio camelus Linnaeus, 1758

In recent years, avian medicine has advanced in the recognition of kidney diseases, but little is known about the morphology and renal morphometry of the common ostrich Struthio camelus Linnaeus, 1758. This study aimed to describe the morphometry and location of kidneys in the common ostrich. Twenty-six cadavers, aged one to seven days, which died of natural causes on a farm in the municipality of Magé, state of Rio de Janeiro, Brazil, were donated to the Department of Animal and Human Anatomy at the Universidade Federal Rural do Rio de Janeiro (UFRRJ). The specimens were identified, sexed, and fixed in a 10% aqueous solution of formaldehyde. The kidneys and renal divisions were measured using a precision digital caliper. The kidneys of S. camelus are elongated, and lobular, and have three renal divisions (cranial, middle, and caudal). The average length of the right kidney was 6.69 ± 0.83 cm, and the left kidney was 6.87 ± 0.81 cm. The body length correlated positively and significantly with the lengths of the right kidney (r = 0.8273, p = 0.0017) and left kidney (r = 0.8534, p = 0.0008) in females. The renal cranial limit was observed at the eighth lumbar vertebra (L8) in 22 kidneys (42.3%), and the caudal limit, at the eighth sacrocaudal vertebra (Sc8) in 11 kidneys (21.2%), and the second caudal vertebra (C2) in 11 kidneys (21.2%). The morphometric dimensions and skeletopy of the ostrich kidney contribute to the field of comparative avian anatomy and assist in the interpretation of imaging techniques.

Water-soluble polymeric probe with tryptophan pendants for formaldehyde sensing

Formaldehyde (FA) is a grade-I carcinogen and the most reactive aldehyde in the carbonyl family, posing substantial health hazards. Herein, a water-soluble polymeric probe with side-chain tryptophan pendants is proposed that relies on an FA-induced Pictet-Spengler reaction for FA sensing in an aqueous medium. The polymeric probe shows cyan fluorescence in an aqueous medium after the interaction with FA due to the formation of a β-carboline derivative, confirmed by high-resolution mass spectrum analysis of the product from the model reaction between tryptophan methyl ester and FA. The copolymer’s sensitivity to FA in aqueous solutions at the nanomolar level is estimated using the fluorescence titration method, where ∼20-fold enhancement in fluorescence intensity is observed within 2 min when 200 µM FA is added to the aqueous solution of the copolymer. The probe can selectively detect FA using colorimetric and fluorometric methods with a detection limit as low as 25 nM. The FA-sensing mechanism is studied from the model reaction of tryptophan methyl ester (TME) with FA, and density functional theory (DFT).

Heterogeneous Oxidase-Type Catalysis for H2 Generation at Low Temperatures.

The long-term objective in the field of heterogeneous catalysis is to develop an enzyme-like catalytic pathway that can achieve exceptional catalytic performance even at low temperatures. Herein, we have demonstrated a heterogeneous oxidase-type catalysis on the ZnO-supported Ru clusters (Ru/ZnO) for efficient H2 generation from an aqueous solution of formaldehyde (HCHO) at low temperatures. Due to its unique reaction pathway, the Ru/ZnO catalysts exhibited a temperature-insensitive activity for H2 generation at the temperature of 15 to 45 °C. Remarkably, even at a low temperature of 5 °C, the Ru/ZnO catalysts still enabled an H2 generation rate of 13.8 mmol gcat-1 h-1 with a turnover frequency (TOF) of 1678 h-1. Additionally, instead of producing a CO2/CO molecule, the HCHO molecule underwent a transformation into formic acid and/or formate as the byproduct. This finding presents a novel class of heterogeneous catalysts to expand the potential application scenarios of liquid hydrogen storage and transportation systems.

Pyrrolic Nitrogen Boosted H2 Generation from an Aqueous Solution of HCHO at Room Temperature by Metal-Free Carbon Catalysts.

Hydrogen production from organic hydrides represents a promising strategy for the development of safe and sustainable technologies for H2 storage and transportation. Nonetheless, the majority of existing procedures rely on noble metal catalysts and emit greenhouse gases such as CO2/CO. Herein, we demonstrated an alternative N-doped carbon (CN) catalyst for highly efficient and robust H2 production from an aqueous solution of formaldehyde (HCHO). Importantly, this process generated formic acid as a valuable byproduct instead of CO2/CO, enabling a clean H2 generation process with 100% atom economy. Mechanism investigations revealed that the pyrrolic N in the CN catalysts played a critical role in promoting H2 generation via enhancing the transformation of O2 to generate •OO- free radicals. Consequently, the optimized CN catalysts achieved a remarkable H2 generation rate of 13.6 mmol g-1 h-1 at 30 °C. This finding is anticipated to facilitate the development of liquid H2 storage and its large-scale utilization.

Gamma-Ray-Induced Amino Acid Formation during Aqueous Alteration in Small Bodies: The Effects of Compositions of Starting Solutions.

Organic compounds, such as amino acids, are essential for the origin of life, and they may have been delivered to the prebiotic Earth from extra-terrestrial sources, such as carbonaceous chondrites. In the parent bodies of carbonaceous chondrites, the radioactive decays of short-lived radionuclides, such as 26Al, cause the melting of ice, and aqueous alteration occurs in the early stages of solar system formation. Many experimental studies have shown that complex organic matter, including amino acids and high-molecular-weight organic compounds, is produced by such hydrothermal processes. On the other hand, radiation, particularly gamma rays from radionuclides, can contribute to the formation of amino acids from simple molecules such as formaldehyde and ammonia. In this study, we investigated the details of gamma-ray-induced amino acid formation, focusing on the effects of different starting materials on aqueous solutions of formaldehyde, ammonia, methanol, and glycolaldehyde with various compositions, as well as hexamethylenetetramine. Alanine and glycine were the most abundantly formed amino acids after acid hydrolysis of gamma-ray-irradiated products. Amino acid formation increased with increasing gamma-ray irradiation doses. Lower amounts of ammonia relative to formaldehyde produced more amino acids. Glycolaldehyde significantly increased amino acid yields. Our results indicated that glycolaldehyde formation from formaldehyde enhanced by gamma rays is key for the subsequent production of amino acids.

An optical fiber sensor based on a B10H14 derivatives/PMMA film for measuring low concentration formaldehyde in aqueous solutions.

The concentration of formaldehyde in the environment must be precisely monitored, as it is closely linked to human health. In this paper, a decaboryl derivative formaldehyde fluorescent probe (M1) was synthesized for the first time by introducing a 5-amino-isoquinoline group into a decaborane parent. Using theoretical calculations, 1H-NMR, 11B-NMR, HR-MS, and FT-IR, the molecular structure of the probe was determined and its response mechanism to formaldehyde was examined. The fluorescence response of the probe to formaldehyde was then tested, revealing an augmented response to formaldehyde in a solution of 0-600 μM, with a detection limit of 4.18 × 10-6 M. The results show that the formaldehyde fluorescence probe has the advantages of good linearity, strong anti-interference and high sensitivity. On this basis, a fiber optic formaldehyde fluorescence sensor based on an M1/PMMA thin film was constructed in this paper. This fiber optic fluorescence sensor, with its high selectivity, low detection limit, online and remote monitoring, and other advantages, was successfully applied to the detection of formaldehyde in both food and aqueous solutions, with results that were reliable compared to those of acetone. The detection limit of formaldehyde increased to 6.9 × 10-8 M. The potential for its utilization in the chemical, biological, environmental, and other formaldehyde detection fields is quite promising.

Modular development of organelle-targeting fluorescent probes for imaging formaldehyde in live cells.

Formaldehyde (FA) is endogenously generated via fundamental biological processes in living systems. Aberrant FA homeostasis in subcellular microenvironments is implicated in numerous pathological conditions. Fluorescent probes for detecting FA in specific organelles are thus of great research interest. Herein, we present a modular strategy to construct diverse organelle-targeting FA probes by incorporating selective organelle-targeting moieties into the scaffold of a 1,8-naphthalimide-derived FA fluorescent probe. These probes react with FA through the 2-aza-Cope arrangement and exhibit highly selective fluorescence increases for detecting FA in aqueous solutions. Moreover, these organelle-targeting probes, i.e., FFP551-Nuc, FFP551-ER, FFP551-Mito, and FFP551-Lyso, allow selective localization and imaging of FA in the nucleus, endoplasmic reticulum, mitochondria, and lysosomes of live mammalian cells, respectively. Furthermore, FFP551-Nuc has been successfully employed to monitor changes of endogenous FA levels in the nucleus of live mammalian cells. Overall, these probes should represent new imaging tools for studying the biology and pathology associated with FA in different intracellular compartments.

Saccharide formation by sustainable formose reaction using heterogeneous zeolite catalysts.

The formose reaction is a unique chemical reaction for the preparation of saccharides from formaldehyde, a single carbon compound. We applied zeolite materials as heterogeneous catalysts to the formose reaction. The simple addition of Linde type A zeolite containing calcium ions (Ca-LTA) to an aqueous solution of formaldehyde and glycolaldehyde produced saccharides at room temperature. A quantitative analysis performed by high-performance liquid chromatography revealed that triose, tetrose, pentose, and hexose saccharides were produced with few byproducts. Ca-LTA was recovered from the reaction mixture by filtration, and the retrieved zeolite was found to be reusable under the same conditions. The catalytic activity of Ca-LTA was higher than those of conventional calcium catalysts and other solid materials such as silica, alumina, and hydroxyapatite. Several other types of zeolites with different crystal structures and alkali/alkali-earth metal ions also showed catalytic activity for saccharide formation. Based on the analytical results obtained by infrared spectroscopy, temperature-programmed desorption profiles and NMR measurements, we propose a reaction mechanism in which C-C bond formation is promoted by the mild basicity of the oxygen atoms and acidity on the metal ions of the aluminosilicate on the zeolite surfaces with low SiO2/Al2O3 ratios.

Сравнительная оценка токсичности и вирулицидных свойств дезинфектантов, применяемых при работе с вирусом SARS-CoV-2 в изолированных вирусологических лабораториях

The choice of disinfectants and their combinations for the final disinfection of the premises of «infectious» areas of laboratories of biosafety level 3–4, in which work is carried out with viruses with epidemic potential, is important for reducing the toxic effect of these disinfectants on personnel while maintaining 100?% disinfection efficiency. Purpose of the study: to study the toxicity of disinfectants of different groups for cell culture, to select a toxicity neutralizer, to study the virucidal activity of these disinfectants and their combinations against the SARS-CoV-2 virus. Materials and methods: experimental studies were carried out using the reference strain of coronavirus SARS-CoV-2, namely the hCoV-19/Australia/VIC01/2020 (AUS) strain (Wuhan variant), obtained from the State Collection of Causative Agents of Viral Infectious Diseases and Rickettsial Diseases, functioning on the basis of the Federal Budgetary Institution State Scientific Center for Virology and Biotechnology «Vector» of Rospotrebnadzor. The residual infectious activity of the virus was determined by titrating samples in cell culture. To conduct the research, we used a Vero E6 cell culture obtained from the Collection of Cell Cultures of the Federal Budgetary Institution of Scientific Research Center for Virology and Biochemistry «Vector» of Rospotrebnadzor in the form of a 2-day monolayer with a confluency of 95–100?%. Results. As a result of the studies, experimental data were obtained on the dynamics of the virucidal activity of different groups of disinfectants and their combinations against the SARS-CoV-2 virus. The degree of toxicity of disinfectants for Vero E6 cell culture is shown. Optimal combinations of disinfectants and a 40?% aqueous solution of formaldehyde (hereinafter referred to as formalin) have been selected, increasing its disinfection efficiency at an initial concentration halved, which can be used for final disinfection treatment of the premises of isolated virology laboratories conducting work with the SARS-CoV- coronavirus. Conclusion. The results obtained indicate that when using selected combinations of disinfectants to carry out final disinfection with formaldehyde vapors formed during the evaporation of formaldehyde as a result of its heating, a twofold decrease in the initial concentration of formalin is possible, leading to a decrease in its toxic effect on personnel, while maintaining 100?% efficiency disinfection. Keywords: disinfection, disinfectants, formaldehyde, SARS-CoV-2 coronavirus, disinfection efficiency, cytotoxicity.

Glyoxal acid-free (GAF) histological fixative is a suitable alternative to formalin: results from an open-label comparative non-inferiority study

Formalin, an aqueous solution of formaldehyde, has been the gold standard for fixation of histological samples for over a century. Despite its considerable advantages, growing evidence points to objective toxicity, particularly highlighting its carcinogenicity and mutagenic effects. In 2016, the European Union proposed a ban, but a temporary permission was granted in consideration of its fundamental role in the medical-diagnostic field. In the present study, we tested an innovative fixative, glyoxal acid-free (GAF) (a glyoxal solution deprived of acids), which allows optimal tissue fixation at structural and molecular level combined with the absence of toxicity and carcinogenic activity. An open-label, non-inferiority, multicentric trial was performed comparing fixation of histological specimens with GAF fixative vs standard phosphate-buffered formalin (PBF), evaluating the morphological preservation and the diagnostic value with four binary score questions answered by both the central pathology reviewer and local center reviewers. The mean of total score in the GAF vs PBF fixative groups was 3.7 ± 0.5 vs 3.9 ± 0.3 for the central reviewer and 3.8 ± 0.5 vs 4.0 ± 0.1 for the local pathologist reviewers, respectively. In terms of median value, similar results were observed between the two fixative groups, with a median value of 4.0. Data collected indicate the non-inferiority of GAF as compared to PBF for all organs tested. The present clinical performance study, performed following the international standard for performance evaluation of in vitro diagnostic medical devices, highlights the capability of GAF to ensure both structural preservation and diagnostic value of the preparations.

Impact of a conditioning step during the treatment of wood with melamine-formaldehyde resin on dimensional stabilisation

Abstract The dimensional stabilisation of wood using thermosetting resins relies on the resin uptake into the cell walls. This study tested if a conditioning step after the impregnation and before the final heat-curing enhances the cell wall uptake to improve dimensional stabilisation without increasing the chemical consumption. Small blocks of Scots pine sapwood were vacuum-impregnated with an aqueous melamine formaldehyde solution and conditioned at 33, 70, or 95 % RH for up to 1 week before drying and curing the blocks at 103 °C. However, the conditioning step decreased the cell wall bulking and the moisture exclusion effect compared to the immediate heat curing of the impregnated samples. Analyses of the resin-treated samples by scanning electron microscopy, IR spectroscopy and confocal Raman microspectroscopy provided evidence of wood hydrolysis and polycondensation of the resin within the cell lumen during the conditioning step. Hydrolysis and removal of wood constituents may have counterbalanced the cell wall bulking of the resin. Polycondensation of the resin in the lumen increased its molecule size, which could have hindered the cell wall diffusion of the resin.

Tandem reactions on phase separated MnO2 and C to enhance formaldehyde conversion to hydrogen

Hydrogen production from formaldehyde aqueous solution at room temperature shows a unique advantage regarding the bi-functional reaction route. MnO2 was reported to be an active catalytic material for this process, especially after coating with carbon composite for improved active site distribution. Here, we unravel that the conversion of formaldehyde can be treated as two tandem half-reactions: the oxidative dehydrogenation (ODH) of formaldehyde and the hydrogen evolution reaction (HER). β-MnO2 in a physical mixture with carbon (i.e., XC-72R, graphene) enhances both formaldehyde conversion (from 13% to 19.5%) and hydrogen productivity (from 22.35 μmol mg−1 h−1 to 33.86 μmol mg−1 h−1) by a synergistic effect of the phase separation catalyst in terms of electron redistribution and transport over the active sites. The catalyst examination supported by DFT calculation shows relatively low activation energy and band gap of β-MnO2 + C with a density of states spanning the Fermi level. The discovery of this novel synergistic catalytic effect: a phase separation catalyst with cooperative enhancement, provides new insight into the area of tandem catalysis.

Production of Bitumen Modified with Low-Molecular Organic Compounds from Petroleum Residues. 8. Prospects of Using Formaldehyde Modified Tars in Road Construction

Modification of tars with formalin (37 % aqueous solution of formaldehyde) was carried out using various acids as process catalysts with the aim of obtaining new binding materials for road construction. H2SO4, HCl, H3PO4, and СH3COOH were used as catalysts. The modification process was carried out in the temperature range of 378-403 K and for a duration of 0.6-1.0 h. The rheological properties of tars modified with formaldehyde at 333, 343, and 353 K were studied and a comparison of the rheological properties of the obtained bituminous binder materials with oxidized bitumens was carried out.

Activated metal Bi and La modified SAPO-34 molecular sieve and its photocatalytic degradation of formaldehyde in aqueous solution

Activated metal Bi and La modified SAPO-34 molecular sieve and its photocatalytic degradation of formaldehyde in aqueous solution

Building synergy between Cu and Ag for efficient hydrogen production from formaldehyde reforming

Building a sustainable society requires efficient chemical storage of hydrogen and facile on-demand generation. In this work, hydrogen is spontaneous generated from reforming formaldehyde and water on bimetallic Ag/Cu NWs catalyst, which is synthesized by a simple wet etching method together with electrochemical reduction. The results indicate that O2 can effectively promote H2 generation by forming *OOH specie, and act as a medium for H atom transfer. The synergistic effect between Ag and Cu greatly improves the catalytic activity. Specifically, the adsorption of O2 on Cu sites promotes the dehydrogenation of formaldehyde and proton coupling on Ag sites. Consequently, the Ag/Cu catalyst expresses excellent hydrogen production from aqueous formaldehyde solution at a rate of 12.3 mmol/(gcat.∙min), which surpass the past record. This work clearly explains the synergistic effect mechanism on formaldehyde reforming from the atomic level, providing guidance for the design of highly efficient catalysts for aqueous-phase spontaneous hydrogen evolution reactions.

Thermodynamic modelling of the nature of speciation and phase behaviour of binary and ternary mixtures of formaldehyde, water and methanol

Formaldehyde is a highly reactive chemical that is usually sold and processed in the form of aqueous solutions, with methanol added for stability. In these solutions, formaldehyde reacts with the solvents to form a variety of reaction products, including oligomers. These chemical reactions can occur in the liquid and vapour phases and have a significant influence on the properties of formaldehyde-containing solutions. Of particular interest to industrial applications is the prediction of the vapour–liquid equilibria (VLE) in formaldehyde solutions, considering the chemical reactions. We use the SAFT-γ Mie group-contribution (GC) equation of state to obtain the fluid-phase behaviour of binary and ternary mixtures of formaldehyde with water and methanol. The oligomerisation reactions taking place in aqueous and methanolic solutions of formaldehyde are modelled implicitly using a physical approach, which is possible within the SAFT-γ Mie framework by adding association (reactive) sites that mediate the formation of the reaction products. Using this approach, the nature of the chemical speciation in formaldehyde + water, formaldehyde + methanol and formaldehyde + water + methanol mixtures is studied. A new group, CHO, characterising formaldehyde within the SAFT-γ Mie GC approach, is developed. Experimental data for the VLE in binary mixtures of formaldehyde + water and formaldehyde + methanol are used to obtain the optimal unlike interaction parameters between the corresponding SAFT-γ Mie groups. The newly developed parameters are used to predict the VLE of ternary formaldehyde + water + methanol mixtures for a wide range of temperatures and pressures, with excellent agreement to experimental data. Additionally, the SAFT-γ Mie approach is shown to provide accurate predictions of the distribution of reaction species (oligomers) in binary and ternary mixtures containing formaldehyde.

Synthesis of anti-tuberculosis drugs in a microwave flow reactor

This article describes the first detailed method for the synthesis of the sought-after anti tuberculosis drugs Methazide (2) and Ftivazide (3) in a microwave flow-type reactor. The process was carried out in water, the time of synthesis of Methazide was reduced by a factor of 36 and of Ftivazide by a factor of 24 as compared with known convection prototypes; the replacement of toxic aqueous formaldehyde solution by safer paraformaldehyde was successfully carried out, all of which makes the proposed method consistent with the principles of the “Green Chemistry“ concept.

Gamma-Ray-Induced Amino Acid Formation in Aqueous Small Bodies in the Early Solar System.

Carbonaceous chondrites contain life's essential building blocks, including amino acids, and their delivery of organic compounds would have played a key role in life's emergence on Earth. Aqueous alteration of carbonaceous chondrites is a widespread process induced by the heat produced by radioactive decay of nuclides like 26Al. Simple ubiquitous molecules like formaldehyde and ammonia could produce various organic compounds, including amino acids and complex organic macromolecules. However, the effects of radiation on such organic chemistry are unknown. Hence, the effects of gamma rays from radioactive decays on the formation of amino acids in meteorite parent bodies are demonstrated here. We discovered that gamma-ray irradiation of aqueous formaldehyde and ammonia solutions afforded a variety of amino acids. The amino acid yields had a linear relationship with the total gamma-ray dose but were unaffected by the irradiation dose rates. Given the gamma-ray production rates in the meteorite parent bodies, we estimated that the production rates were reasonable compared to amino acid abundances in carbonaceous chondrites. Our findings indicate that gamma rays may contribute to amino acid formation in parent bodies during aqueous alteration. In this paper, we propose a new prebiotic amino acid formation pathway that contributes to life's origin.

Photoinduced electron-rich CuNi@C/TiO2 catalyst for highly efficient hydrogen production from formaldehyde aqueous solution

Catalytic conversion efficiency from aqueous formaldehyde (HCHO) into hydrogen (H2) on non-noble metal catalysts is much lower than that on noble metal catalysts. Modulating the electronic properties of non-noble metal-based catalysts has been demonstrated an effective approach to improve their catalytic performance. In this work, assisted by light irradiation, photoinduced electron-rich surface structure was designed for the thermal catalytic conversion of HCHO to H2. In detail, a heterostructure of CuNi@C composited with TiO2 was obtained, in which TiO2 can be photoexcited under light irradiation to provide photoinduced electrons onto the surface of CuNi@C. On the photoinduced electron-rich surface of the CuNi@C/TiO2 heterostructure, the H2 evolution rate reached 254.65 mmol h−1 g−1, which was 1.88 times higher than that on CuNi@C. It is worth noting that the catalytic HCHO conversion efficiency outperforms the current reported non-noble metal catalysts for this reaction. Combining with density functional theory (DFT) calculations and experimental studies, it is concluded that the electron-rich CuNi@C dramatically reduced the activation energies of the dissociation of HCHO and H2O and accelerated the overall reaction rate.