Formaldehyde In Aqueous Solution Research Articles

Catalytic Decomposition of Formaldehyde on Nanometer Manganese Dioxide

In this paper, nanostructure MnO2 was synthesized in aqueous solution, without using any templates, catalysts, and organic reagents. The as-prepared nano-MnO2 was systematically characterized by X-ray diffraction (XRD), and transmission electron microscopy (TEM) Fourier transform infrared (FT-IR) spectroscopy analysis. The catalytic decompositions of HCHO were studied at different conditions using the nano-MnO2 as catalyst. The resulting nano-MnO2 particles were found to exhibit remarkable environmental catalytic performance in catalytic decomposition of formaldehyde in aqueous solution.

O sistema carótico do encéfalo do Cebus apella sp., Linnaeus, 1766

Estudamos em trinta espécimes do primata Cebus apella sp. (Linnaeus, 1766) o sistema carótico do encéfalo em animais coletados dentro dos parâmetros internacionais de bioética e bem estar animal. O material teve o sistema arterial perfundido (água a 40 °C), injetado com látex corado (Neoprene 450, Dupont® do Brasil e Sulvinil® Corante, Glassurit), fixado em solução aquosa de Formaldeído (10%) dissecado sob lupa (RASOR - II - 20) para sistematização dos vasos. O sistema carotico é composto pela porção intracraniana e intradural dos seguimentos dependentes das artérias carótidas internas esquerda e direita, as artérias carótidas do encéfalo (ace) e seus ramos de divisões látero-mediais e ântero-mediais: as artérias cerebrais médias acm e rostrais (acr), comunicantes caudais e artérias corioídeas Está interligado, através das artérias comunicantes caudais, ao sistema vértebro-basilar (100%). A ace termina trifurcando-se (50%), ou bifurcando-se (50%) em arranjos vasculares que envolvem as acm e acr, acc e artéria corioídea. A acm é o ramo mais estável deste circuito e a acr após vascularizar os bulbos olfatórios (93,3%) anastomosa-se com a artéria contralateral formando a artéria inter-hemisférica que conecta rostralmente os leitos sanguíneos do circuito arterial da base do encéfalo. Pode-se considerar que o Cebus apella sp. depende de duas fontes de suprimento para o encéfalo: os sistemas basilar e carotídico, isto indica um grau elevado de maturidade evolutiva. A ausência de anomalias demonstra neste primata estabilidade evolutiva.

Low-Temperature Preparation and Characterization of Nanocrystalline Anatase TiO2

Nanoanatase TiO2 of high crystallinity was prepared by a novel simple route at a temperature of 100 °C under mild conditions. Tetrabutyl titanate was used as a titanium precursor, Acetic acid was used as an inhibitor, and diethyl ether anhydrous was used as a solvent. X-ray powder diffraction (XRD), laser Raman spectroscopy (Raman), BET surface area analysis, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and UV−vis diffuse reflectance spectra (DRS) were applied to characterize the crystallinity, morphology, surface structure, and other physicochemical properties of the nanoanatase TiO2. The photocatalytic activity of the prepared photocatalyst was evaluated by the photodegradation of formaldehyde in aqueous solution and compared with the commercial photocatalyst, namely, Degussa P-25. The result showed that the sample prepared at low temperature showed photocatalytic activity. The activity of the sample prepared at 120 °C was high and close to the sample calcined at ...

Water-tolerant zeolitecatalyst for the acetalisation of glycerol

We studied the acid-catalysed reaction of glycerol with aqueous formaldehyde and acetone in absence of solvents and using heterogeneous catalysts. The reactivity of acetone was usually higher than formaldehyde and the glycerol conversion was over 90% within 40 min of reaction time for all the heterogeneous acid catalysts studied. With aqueous formaldehyde solution, the glycerol conversion was within 60 to 80%, depending upon the acid catalyst used (Amberlyst-15, K-10 montmorillonite, p-toluene-sulfonic acid), due to the high amount of water in the reaction medium, which shifts the equilibrium and weakens the acid sites. However, the use of zeolite Beta, with Si/Al ratio of 16, leads to a conversion of over 95% within 60 min of reaction time. The hydrophobic character of the zeolite, due to the high silicon content, prevents the diffusion of the water to the interior of the pore, preserving the strength of the acid sites. In addition, the water formed during the acetalisation is expelled off from the pore environment, impairing the reverse reaction, and avoiding the use of hazard solvents, commonly employed to distil off the water formed.

Cross Determination of the Vapor Liquid Equilibrium of Formaldehyde Aqueous Solutions by Quadrupole Mass Spectrometry and Infrared Diode Laser Spectroscopy

Quantitative measurements of the partial vapor pressure of formaldehyde are performed above aqueous H2CO solutions of different concentrations (from 10(-5) to 0.3 molar fraction) using mass spectrometry and IR diode laser spectroscopy. Both experimental techniques allow direct probing of the gas phase concentration collected at equilibrium above the aqueous solutions. A correlation is observed between the polymerization processes occurring in the solution and the partial pressure of H2CO measured at vapor liquid equilibrium (VLE). A similar correlation is observed from total pressure measurements for which the equilibrium vapor pressure decreases as [VLE XH2CO]liq is increased. A saturation regime of the H2CO partial pressure is reached as the dissolved fraction of formaldehyde increases above approximately 0.15 mol frac. Henry's law constants are derived at 295K for the diluted solutions.

Anatomia dos ramos do nervo lingual em suíno

The distribution and ramifications of the lingual nerve of 18 tongues of adult pigs from both genders with no strain specification were studied. The material freshly collected in slaughter routine was cooled (4°C) for transportation, fixed in formaldehyde aqueous solution (7%, 72h), immerse in nitric acid aqueous solution (15%, 72h) and dissected with magnifying glass (RASOR, II-20). Each dissected antimere enabled the recording of primary, secondary and tertiary lingual nervous branches present inside the myofascial structure of the organ, exhibiting different arrangements: left antimere: 4 to 10 primary branches, 4 to 12 secondary antimeres and 0 to 11 tertiary branches; right antimere: 3 to 8 primary branches, 0 to 11 secondary antimeres and 0 to 10 tertiary branches. In 27.6% of analyses, the lingual branches established associations with the fibers of the hypoglossal nerve in the corresponding antimere.

Spectrophotometric technique for determining simultaneously present formaldehyde and formic acid

A precise sensitive spectrophotometric method was developed for determining formaldehyde in aqueous solutions. The possibility of joint determination of formaldehyde and formic acid was examined.

Aspectos morfológicos e morfométricos da traquéia em gansos domésticos

Morphologic and morphometric aspects of the domestic geese trachea. The tracheal morphology of 31 domestic geese was studied in order to characterize the morphometric and macroscopic aspects. Domestic geese, adult, male and female, from regular breeders, were utilized. The animals were euthanized by chloroform inhalation and fi xed in 10% formaldehyde in aqueous solution. The trachea was dissected, beginning caudal at

Use of Data-Driven Model to Optimize Scale-up Production of Nanosized Silver Particles

Optimization of the synthesis of nanosized silver particles by chemical reduction using formaldehyde in aqueous solution was carried out based on small-scale experimental data (with a 100 cc reaction mixture loaded in a 200 cc beaker and shaken in an isothermal shaker). Effects of the possible processing variables were achieved. In this study, the scale-up production (2 L or more of the reaction mixture) of nanosized silver particles is intended; however, for a scale-up system, the experiments generally require large and expensive resources. To obtain the optimal recipe and operating conditions using limited resources for a scale-up system, an algorithm for extending the identified model built from a small-scale system to a scale-up system was first developed through a numerical example. On the basis of the developed algorithm, 19 experiments were carried out in the scale-up system to achieve the objectives (minimum of the mean particle size of the silver colloid with or without the constraint of conversi...

Ramos colaterais parietais e terminais da aorta abdominal em Myocastor coypus (nutria)

Neste estudo, utilizaram-se 30 nutrias, 15 fêmeas e 15 machos, com o sistema arterial aórtico-abdominal preenchido com látex 603, pigmentado em vermelho, e fixado em uma solução aquosa de formaldeído a 20%. A aorta abdominal emitiu de sua superfície dorsal de 6 a 8 artérias lombares únicas. Das artérias renais, direita e esquerda, originaram-se as artérias frênico-abdominal para irrigar parte do diafragma e da parede abdominal lateral cranial. A aorta abdominal lançou dorsalmente, a artéria sacral mediana, cranialmente a sua bifurcação em artérias ilíacas comuns. As artérias ilíacas comuns, ramos terminais da aorta abdominal, originaram as artérias ilíacas interna e externa. A artéria ilíaca interna distribuiu-se nas vísceras da cavidade pélvica. A artéria ilíaca externa emitiu uma artéria umbilical e, antes de alcançar o anel femoral, lançou a artéria circunflexa ilíaca profunda para a parede abdominal lateral, em seus dois terços caudais. A artéria ilíaca externa lançou o tronco pudendo-epigástrico, que originou a artéria epigástrica caudal, para a parede abdominal ventral e a artéria pudenda externa, que saiu pelo canal inguinal, para irrigar a genitália externa. Os ramos parietais diretos da aorta abdominal foram as artérias lombares e a artéria sacral mediana, enquanto as artérias frênico-abdominal, circunflexa ilíaca profunda e epigástrica caudal, foram ramos colaterais parietais indiretos. Os ramos terminais da artéria aorta abdominal foram as artérias ilíacas comuns com seus ramos, as artérias ilíacas interna e externa.

LOBAÇÃO, ÁRVORE BRÔNQUICA E VASCULARIZAÇÃO ARTERIAL DO PULMÃO DA PACA (Agouti paca, LINAEUS, 1766)

Lungs are the main organs of the respiratory system and the morphological knowledge of lobation, bronchial tree and arterial vascularization becomes indispensable on clinics and surgery practice. The pulmonary trunks of 10 lungs were filled with latex and the anatomical sets were put in a 10% formaldehyde aqueous solution. By dissection, it was observed that, in 100% of the cases, the right lung was constituted by cranial, medium, caudal and accessory lobes. The medium lobe was divided into cranial and caudal portions. The left lung presented a cranial lobe, divided into cranial and caudal portions, a caudal lobe and a little accessory lobe. The right pulmonary artery gave off two branches to the cranial lobe, besides branches to the cranial and caudal portions of the medium lobe, and branches to the accessory and caudal lobes. The left pulmonary artery gave off two branches to the cranial and one to caudal portions of the cranial lobe; the left caudal lobe was supplied by the left pulmonary artery continuation, which gave off five to six dorsal and seven to eight ventral branches. There was no variation on the studied lungs as for lobes or bronchial tree model. KEY WORDS : Agouti paca, lungs, pulmonary artery, rodent.

An electronic signature of hydrolysation in the X-ray absorption spectrum of aqueous formaldehyde

Formaldehyde in aqueous solution is hydrolysed and forms methanediol. Using X-ray absorption spectroscopy we show that the hydrolysation product can be identified by a distinct electronic signature in the spectra. This is manifested by the disappearance of the oxygen 1s → π* absorption line. The X-ray absorption spectrum of aqueous formaldehyde is compared with those of the structurally similar formamide and urea, which are in contrast not hydrolysed in aqueous solution. We thereby demonstrate the exceptional sensitivity and simplicity of the technique to monitor this fundamental process in the aqueous phase.

Scandium(III) Fluoride as a Novel Catalyst for Hydroxymethylation of Dimethylsilyl Enolates in Aqueous Media

Hydroxymethylation of dimethylsilyl (DMS) enolates using aqueous formaldehyde solution is catalyzed by scandium(III) fluoride (ScF3) in aqueous media to give the corresponding β-hydroxy ketones in good to excellent yields. Whilst the DMS enolate reactions are facile the TMS enolates react sluggishly under the same conditions. ScF3 has been shown to be a unique catalyst for this reaction.

Passive Emission Colorimetric Sensor (PECS) for Measuring Emission Rates of Formaldehyde based on an Enzymatic Reaction and Reflectance Photometry

A coin-sized passive emission colorimetric sensor (PECS) based on an enzymatic reaction and a portable reflectance photometry device were developed to determine the emission rates of formaldehyde from building materials and other materials found indoors in only 30 minutes on-site. The color change of the PECS linearly correlated to the concentration of formaldehyde aqueous solutions up to 28 microg/mL. The correlation between the emission rates measured by using the PECS and those measured by using a desiccator method or by using a chamber method was fitted with a linear function and a power function, and the determination coefficients were more than 0.98. The reproducible results indicate that the emission rates could be obtained with the correlation equations from the data measured by using the PECS and the portable reflectance photometry device. Limits of detection (LODs) were 0.051 mg/L for the desiccator method and 3.1 microg/m2/h for the chamber method. Thus, it was confirmed that the emission rates of formaldehyde from the building materials classified as F four-star (< 0.3 mg/L (desiccator method) or < 5.0 microg/m2/h (chamber method)), based on Japanese Industrial Standards (JIS), could be measured with the PECS. The measurement with PECS was confirmed to be precise (RSD < 10%). Other chemicals emitted from indoor materials, such as methanol, ethanol, acetone, toluene, and xylene, interfered little with the measurement of formaldehyde emission rates by using the PECS.

Nano-Cu catalyze hydrogen production from formaldehyde solution at room temperature

In this paper, high efficient production of CO-free hydrogen from formaldehyde (HCHO) aqueous solution catalyzed by various nano-metal catalysts was reported. It was found that nano-metal catalyst could catalyze formaldehyde into hydrogen and formic acid under room temperature and atmospheric pressure. Among Pt, Au, Ni, and Cu nano-metal particles, nano-Cu catalyst exhibited the highest activity and the long-term stability. The temperature seems influence the reaction significantly. For example, when the temperature was increased from 0 to 60 °C, the rate of hydrogen production increases from 2.34 to 140 mL min −1 g −1 catalyst over nano-Cu catalyst. Hydrogen was produced via the formic acid intermediate. When NaOH concentration was high, Cannizzaro reaction occurred, which resulted in the retardation of hydrogen generation at high concentration of NaOH and HCHO.

Development of Carbon Coatings for Cordierite Foams: An Alternative to Cordierite Honeycombs

Cordierite foams were prepared by replication of polyurethane foams and were coated with three types of carbon xerogels. The dip coating and synthesis conditions were optimized, and the coated foams were characterized exhaustively. The composition of the starting solution, coat loading, and carbonization temperature are the most important parameters determining both textural and mechanical properties. Carbon xerogel coatings obtained from aqueous solutions of resorcinol (R) and formaldehyde (F) are macro-, meso-, and microporous but present the greatest shrinkage, which causes a loss of adhesion between ceramic foams and carbon coatings. The coatings from polyfurfuryl alcohol (PFA) and RF-poly(vinyl butyral) (Butvar) resin are highly microporous and present very good adhesion even after carbonization. In all cases, coatings induce the improvement of the mechanical properties, which is related to the fact that the coating fills the defects present in the cordierite foams, thereby affecting both the rigidity and the way cracks propagate through the coated samples. These materials, due to the synergetic role of the highly porous coatings and the tortuous channels of the ceramic foams, are suitable materials for adsorption or catalytic treatments of fluids.

Distribuição intraparenquimal da artéria hepática em cutias (Dasyprocta sp, Rodentia)

Com o objetivo de analisar a ramificação da artéria hepática e sua distribuição intraparenquimal em cutias, foram utilizados dez fígados de cutias adultas, fêmeas e machas, cedidas pelo Núcleo de Estudos e Preservação de Animais Silvestres do Centro de Ciências Agrárias da Universidade Federal do Piauí (Convênio FUFPI/IBAMA número 02/99). Oito fígados foram dissecados pela face visceral após injeção com látex do tipo Neoprene 650 (DuPont do Brasil Industrias Químicas) corado em vermelho, através da artéria hepática, e fixados em solução aquosa de formol a 10%, durante pelo menos 48 horas. Dois órgãos foram utilizados para a confecção dos moldes vasculares, através de injeção de solução de acetato de vinil corado em vermelho e corrosão em solução aquosa de ácido clorídrico a 30% até total destruição do parênquima. O estudo das peças mostrou que a artéria hepática na cutia divide-se em dois ramos principais, direito e esquerdo (100%). De forma geral, o ramo direito predominantemente (80%) origina vasos responsáveis pela vascularização dos lobos medial direito, lateral direito e caudado. O ramo esquerdo apresenta-se com maior freqüência (80%) constituindo um tronco comum aos vasos que se destinam aos lobos lateral esquerdo, medial esquerdo, quadrado, em 50%, também ao lobo caudado e em 20% ao lobo lateral direito. Sendo assim, conclui-se que a distribuição vascular da artéria hepática está relacionada à lobação do órgão, onde os ramos direito e esquerdo se distribuem no parênquima dos lobos do fígado, podendo-se inferir a presença de territórios com vascularização própria nos lobos hepáticos, caracterizando, portanto, a segmentação anátomo-cirúrgica arterial.

Ice mixtures formed by simultaneous condensation of formaldehyde and water: an in situ study by micro-Raman scattering

Thin films of formaldehyde-water mixtures are co-deposited at 88 K and 10(-1) Torr from gas collected above formaldehyde aqueous solutions of different concentrations (5, 10, 15, 20, 30 mol%). They are analyzed in situ by micro-Raman scattering in the 2700-3800 cm(-1) spectral range. The spectral characteristic of H2CO distributed molecularly in amorphous solid water is obtained under vacuum conditions. As temperature is increased formaldehyde is released during the crystallization of ice between 118 and 138 K. On the other hand, under controlled nitrogen atmosphere, the deposits crystallize in hydrate phases (or solid H2CO(s)) during annealing. A new phase (metastable FOR-A) of H2CO(s) (or a low hydrate after rejection by crystallizing ice) can be spectroscopically identified at 138 K before transformation into a hydrate (with molecular H2CO distributed within the cages of the clathrate FOR-B) takes place at 148 K. This latter phase decomposes between ca. 180 and 200 K. The significant spectral differences between these hydrates and those formed in frozen formaldehyde aqueous solutions reflect the existence of H2CO-clusters of distinctive structural nature relative to those resulting from important oligomerization process in the liquid. Moreover, the structure, the gas distribution and relative gas population in the formaldehyde clathrate cages are influenced by the relative amount of trapped nitrogen at the surface, which moreover depends on the ice film morphology. The dependence on the crystallization temperature of the deposits is explained by the relative amounts of occluded H2CO/N2 and the external pressure conditions. The distinct behavior observed between vacuum and N2-atmosphere conditions certainly reflects a complex mechanism of surface mediated nucleation in which the transport of the reactants to the hydrate reaction zone is facilitated by the presence of a polar dopant.

Optimization of Nanosized Silver Particle Synthesis via Experimental Design

Highly dispersed silver nanoparticles could be used as catalysts, as staining pigments for glasses and ceramics, as antimicrobial materials, in surface-enhanced Raman spectroscopy, as transparent conductive coatings, in electronics, etc. Consequently, the versatility of such particles provides strong incentives to the development of a systematic way to produce their dispersions. In this work, the optimization of the synthesis of nanosized silver particles by chemical reduction using formaldehyde in aqueous solution was studied. Effects of the possible processing variables such as the reaction temperature T, the mole ratio of [formaldehyde]/[AgNO3], [NaOH]/[AgNO3], the weight ratio of PVP/AgNO3, and the molecular weight (MW) of protective agent PVP (Polyvinyl−pyrrolidone) were considered. The data-driven model on the basis of the 44 designed experimental runs provided us the optimal conditions for closely achieving the product with the specified mean particle size and conversion of silver nitrate.

A fuel-cell-type sensor for detection of formaldehyde in aqueous solution

A direct formaldehyde fuel cell using PtRu black as anode catalyst in membrane electrolyte assembly (MEA) has been fabricated for detecting formaldehyde in aqueous solution. The sensor shows high sensitivity for formaldehyde with good linearity over a wide concentration range from 0.002 to 1.25 mg ml −1 and the response time is within tens of seconds. According to voltammetric results, the PtRu black electrode shows a comparable electro-oxidizing catalytic activity for formaldehyde to methanol and high stability in monitoring formaldehyde through long-term test. By analyzing the results at different temperatures, the electrochemical reaction determines the response of the sensor, which is comparable to that of mass transfer process. Moreover, the effect of load resistance on the performance of the sensor was investigated: a small resistance is preferred for detecting higher concentrations and a high resistance is preferred for detecting lower concentrations. Through water absorption, the fuel-cell-type sensor can also detect gaseous formaldehyde concentration.