Showing papers on "Oxalic acid published in 1989"

The Effect of Organic Acids on the Dissolution of K-feldspar Under Conditions Relevant to Burial Diagenesis

Abstract: The mechanism by which secondary porosity in sandstone reservoirs is produced is poorly understood. Previous hypotheses to account for the increased dissolution of framework silicates have invoked the introduction of acidic and/or organic-rich fluids capable of complexing metals. In order to evaluate the relative effects of these factors, the rates of K-feldspar dissolution have been measured at 70 ~ and 95 ~ at pH values of 1, 4, and 9, with and without oxalic acid, at a total pressure of 50 MPa, using direct sampling autoclaves. The presence of oxalic acid increased the dissolution rate of Kfeldspar at pH 4 and 9, but decreased the rate at pH 1 at both temperatures. The maximum increase in dissolution rate was observed at pH 4, 95 ~ by a factor -4. In oxalic-free experiments, the rate of dissolution increased an order of magnitude with each unit decrease in pH in the pH regime 1--4. In the presence of oxalic acid, this dependency of dissolution upon pH decreased to approximately an order of magnitude increase with each decrease in pH by 2pH units. The dissolution process was observed to be stoichiometric under all conditions, indicating that the mechanism by which rates are increased was not due to preferential complexation of aluminium, but rather by an increase in the overall solubility of feldspar in the neutral pH region. This regime of increased rate of reaction of feldspar coincides with that expected to be naturally buffered by the introduction of organic acids into a sandstone reservoir system.

Disease suppression by the ectomycorrhizal fungus Paxillus involutus: contribution of oxalic acid

Abstract: Seedlings of Pinus resinosa Ait. grown in test tubes were inoculated with the ectomycorrhizal fungus Paxillus involutus Fr. Oxalic acid was identified as one of the ethanol-soluble fungistatic and (or) fungitoxic components of the rhizosphere after fractionation by high performance liquid chromatography, paper chromatography, and gel filtration. Simultaneous inoculation of P. resinosa seedlings with authentic oxalic acid and a spore suspension of Fusarium oxysporum f.sp. pini protected the seedlings against Fusarium root rot and decreased the sporulation of F. oxysporum in the rhizosphere when compared with controls lacking oxalic acid. Quantitation of oxalic acid showed a five fold increase in production by Pax. involutus in tubes containing P. resinosa seedlings when compared with tubes lacking seedlings. The synthesis of oxalic acid by Pax. involutus is, therefore, stimulated by P. resinosa root exudate.

Creamy hair dye composition

Abstract: PURPOSE:To obtain the title composition with hardly any effects on human bodies and irritant smell even if ammonia is contained for providing hair dyeing treatment effects, by adding an oily ingredient and surfactant to an alkaline agent containing ammonia and ammonium salt, water and oxidation dye intermediate. CONSTITUTION:A creamy hair dye composition containing an alkaline agent containing ammonia and an ammonium salt (especially preferably ammonium salts of hydrochloric acid, nitric acid, sulfuric acid, bisulfuric acid, phosphoric acid, acetic acid, oxalic acid and citric acid), water, an oxidation dye intermediate, an oily ingredient (especially preferably paraffin, liquid paraffin, bees wax, squalane, vaseline, lanolin, silicone derivative, higher fatty acid and higher alcohol) and a surfactant (e.g., alkyltrimethylammonium salt). The above- mentioned composition especially preferably contains 1-10wt.% aqueous ammonia in 28% concentration and 0.1-10wt.% ammonium salt and is adjusted to pH8-12.

Selective Recovery of Trace Scandium from Acid Aqueous Solution with (2-Ethylhexyl hydrogen 2-ethylhexylphosphonate)-Impregnated Resin

Abstract: A reagent-impregnated resin prepared from 2-ethylhexyl hydrogen 2-ethylhexylphosphonate (PC-88A) and Amber-lite XAD-7 beads was examined in order to apply it to the selective recovery of scandium. The distribution ratio of scandium to the present resin is extremely high (log D_??_6), even in highly concentrated acids. The separation factors between Sc(III) and other common metal ions including Fe(III) are sufficiently large to allow effective separations. The selective recovery of Sc(III) from the acid-leached solutions of wolframite and tin slag has been carried out by using the present resin as the column stationary phase. The retained Sc(III) is released from the resin quantitatively by elution with 4-methyl-2-pentanone. Scandium has been isolated as a precipitate by treating Sc-PC-88A complex with oxalic acid in ethanol.

Process for preparing pyridine-2,3-dicarboxylic acid compounds

Abstract: A pyridine-2,3-dicarboxylic acid compound represented by general formula (I) (wherein R1 and R2 may be the same or different and each represents a lower alkyl group, and R3 represents a hydrogen atom or a lower alkyl group) is prepared by reacting an alkali metal salt of oxalacetic acid diester with an acid and a halogenating agent or reacting an oxalic acid diester with a haloacetic acid ester to obtain an alpha-halooxalacetic acid diester, and reacting the formed diester with a 2-propenal compound and ammonia. The obtained compounds are useful as intermediates for agricultural chemicals and medicines.

Oxalate in vegetable Amaranth (Amaranthus gangeticus). forms, contents, and their possible implications for human health

Abstract: Forms of oxalate in Amaranthus gangeticus L (a vegetable amaranth) grown in three sites with different soil and climatic factors were identified, and their contents were determined. On average the total oxalate content was 91 g kg−1 on a dry weight basis. This is high when compared with the amounts reported to be a health hazard in other vegetables and forage crops. Two dominant fractions of oxalate in amaranth were isolated: a fraction soluble in boiling water which was predominantly in the form of potassium and magnesium oxalate, and an associated insoluble residue which was predominantly calcium oxalate. Most of the Ca in amaranth is unlikely to be available to the body. A suggestion was made that research on reducing the oxalate content of amaranth should first be directed at soluble oxalates because they can interfere with Ca availability from other food sources.

Preparation of Bi-Pb-Sr-Ca-Cu-O high Tc superconducting material via oxalate route at various pH values

Abstract: A method for coprecipitation of Bi-Pb-Sr-Ca-Cu-O superconducting material via the oxalate route is presented. Bismuth, lead, strontium, calcium and copper nitrates and oxalic acid are used as starting materials. The precipitation of precursor from these materials is studied at different pH values The compositions of the coprecipitated powders are determined by direct current plasma atomic emission spectrometry. Two useful pH regions for precipitation are found. The first is a low pH region between 2 to 4 and the second is a high pH region of over 10. The precursors and sintered bulk samples are investigated by TEM, SEM/EDS and XRD. Resistivity measurements are carried out. The composition of the decomposed precursor is found to be homogeneous. The decomposed precursor has a particle size of around 300 nm. The sintered material consists of approximately 50% of the high T c phase and shows zero resistance at 104 K.

Process for chemically decontaminating the surface of a metallic construction element of a nuclear power plant

Abstract: The invention relates to a process for chemically decontaminating the surface of a metallic construction element of a nuclear power plant. It is provided that the surface is treated in a single-stage process with an aqueous solution which is free from the carboxylic acid oxalic acid and contains another carboxylic acid (3, 6, 8, 11, 12). Suitable carboxylic acids are dihydroxytartaric acid (6), tartronic acid (8) or mesoxalic acid (3). … …

Sclerotinia sclerotiorum growth and oxalic acid production on selected culture media

Abstract: Two isolates of Sclerotinia sclerotiorum, the highly aggressive (B24) and the weakly aggressive (SS41), were grown on liquid media containing one of the following carbon sources: purified cell walls obtained from onion or sunflower, pectin, polygalacturonic acid, carboxymethylcellulose, xylan or arabinogalactan. Isolates were equally able to utilize these substrates for mycelial growth but differed in their ability to utilize them for oxalate production. B24 produces oxalic acid always to a substantial extent, SS41 only in traces. The poor ability to produce oxalic acid by SS41 seems to be due to a lower efficiency in the synthetic pathway.

Effect of degumming reagents on the composition and emulsifying properties of canola, soybean and sunflower acetone insolubles

Abstract: Acetone insolubles (AI) extracted from crude canola, soybean and sunflower oils using six degumming reagents (water, citric, phosphoric and oxalic acids plus acetic and maleic anhydride) were separated into phospholipid (PL) components by HPTLC. The separated PL were quantified by phosphorus determination. Statistical analysis of the PL composition data indicated that the chemical degumming reagents did not dramatically alter the PL profiles although some significant differences were observed. Acetone insolubles recovered by water degumming produced the most stable oil-in-water emulsions. Those AI isolated by citric acid, acetic anhydride and maleic anhydride treatments produced slightly less stable emulsions but showed good potential as emulsifying agents. Phosphoric and oxalic acid treatments produced AI with very poor emulsifying properties.

Corrosion Behavior of Mild Steel and Ferritic Stainless Steels in Oxalic Acid Solution

Abstract: The corrosion behavior of mild steel (SS 41 [UNS K02600]) and ferritic stainless steels (type 430 [UNS S43000], type 444 [UNS S444001) in oxalic acid solutions was investigated by corrosion weight loss, DC polarization, and natural electrode potential (NEP) variations with time. The surfaces of the specimens were observed by scanning electron microscopy (SEM) and analyzed by x-ray photospectroscopy (XPS). In corrosion weight-loss tests at room temperature, the corrosion rate of SS 41 steel and type 430 stainless steel increased with increasing concentration of oxalic acid, but in the case of type 444 stainless steel, the weight loss was negligible. At the boiling point the corrosion rate of each steel increased with increasing oxalic acid concentrations. The corrosion rates of SS 41 steel and type 444 stainless steel were almost the same, and the value of type 430 stainless steel was greater than that of other steels. When the surfaces of type 430 and type 444 stainless steels were observed by SE...

Process for preparing compound metal oxides of yttrium, barium and copper

Abstract: A process for preparing compound metal oxides, superconductive compound oxides, is disclosed. The process comprises preparing an aqueous solution containing a predetermined content ratio of chloride, nitrate or acetate of a rare earth metal, an alkaline earth metal and copper, said content ration corresponding to the composition of the object compound metal oxide, adjusting the pH of the solution to 1.5-2.0, adding oxalic acid in an amount such that the concentration of the residual oxalic acid becomes 0.05 M/l-0.1 M/l, collecting the thus formed precipitate and firing it.

Stirring rate effect in the closed, batch Belousov–Zhabotinsky system with oxalic acid

Abstract: Oxalic acid can produce oscillations in the Belousov–Zhabotinsky‐type reaction in a closed batch system without a mechanism for bromine removal. The stirring rate has a significant effect on the reaction.

Ion exchange method for the purification of scandium

Abstract: A process is disclosed for purifying scandium from an acid solution containing scandium and various impurities. The process involves mixing the acid solution with a chelating resin in the hydrogen form to from a slurry and packing the slurry in a short ion exchange column. The ion exchange column is rinsed with a mineral acid and the scandium is removed by passing diglycolic acid through the column. The diglycolic acid containing scandium is then passed through a chelating resin in the H form. When the scandium concentration in the effluent from the chelating resin reaches a preselected level the effluent of digylcolic acid and scandium is collected. Collection is stopped when the scandium concentration in the eluent falls below a preselected level. This collected eluent is passed through a strong cation exchange column where the scandium is collected. After rinsing the strong cation exchange column with deionized water, the scandium is removed from the column by passing a solution of ammonium nitrate through the strong cation exchange resin. The scandium is precipated from the ammonium nitrate by adding oxalic acid. The precipate of scandium oxalate is collected by filtration and rinsed. The precipate is calcined at approximately 975° C. to form scandium oxide. This process is applicable to the recovery and purification of scandium from any acid soluble matrix.

Wet chemical techniques for passivation of YBa2Cu3O7−x

Abstract: Wet chemical techniques are described for treatment of YBa2Cu3O(7-x) surfaces, resulting in the formation of native compounds with little or no reactivity to water. Promising native compounds include CuI, BaSO4, CuS, Cu2S, and the oxalates, all of which are either insoluble or have very low solubility in water. Treatment with dilute HI results in the formation of a native iodide film which is 80-90 percent CuI with small amounts of YI3 and BaI2. Treatment with dilute H2SO4 results in the formation of a film which is 95 percent BaSO4 and 5 percent Y2(SO4)3. Cu2S is formed on the surface with a dilute Na2S solution. An oxalate film with equal amounts of Y2(C2O4)3 and BaC2O4 results from treatment with dilute oxalic acid. X-ray photoelectron spectra show no significant changes when the sulfide, sulfate, or oxalate films are dipped in water, while the iodide film shows evidence of Cu(OH)2 formation.

Method of manufacturing barium titanate BaTiO3

Abstract: A method of manufacturing barium titanate (BaTiO3) (BaTiO(C2 O4)2. 4H2 O), is by pyrolysis of barium titanyl oxalate, an provided in which aqueous solution of barium chloride (BaCl2) is added dropwise while stirring vigorously to an aqueous solution comprising a mixture of oxalic acid (H2 C2 O4) and titanium oxychloride (TiOCl2) having a temperature in the range from 20° to 60° C. to form barium titanyl oxalate, the resultant precipitate being calcined at a temperature in the range from 960° to 1200° C.

The γ-irradiation of aqueous solutions of urea. Implications for chemical evolution

Abstract: 0.05 mole dm−3, O2-free aqueous solutions of urea were studies after receiving various doses of60Co gamma rays (0.14–600 kGy). Urea was found to be relatively stable under radiation; its radiation chemical yield of decomposition was 0.47. Hydrogen (G=0.50), carbon dioxide (G=0.44), ammonia (G=0.22), oxalic acid (G=0.0054), malonic acid (G=0.000064) and three unidentified oligomers were found to be the main radiolytic products. The origin of these products is explained by free radical reactions initiated by the transients from water radiolysis (H·,·OH,eaq−).

Mesure De L'oxalate Par Une Electrode A Oxalate-Oxydase Immobilisee Sur Membrane De Collagene

Abstract: Carboxyl groups on a collagen membrane were activated with the aid of an acyl-azide reaction. the enzyme oxalate oxidase, prepared from barley seedlings, was subsequently immobilized on the activated collagen film. the specific activity and the Michaelis constant were 0.13 units/cm2 and 0.1 M, respectively. Enzyme activities were determined as function of pH, ionic strength, and ambient chloride concentration, intercomparing the enzyme in aqueous solution with its immobilized counterpart. Oxalate was quantitated amperometrically via electrooxidation of the hydrogen peroxide by-product generated in the reaction between oxalic acid and O2. the detection limit of oxalate was 10−5, which yielded a current of 2 nanoampere.

Porous titanium oxide fine particle and production thereof

Abstract: PURPOSE: To obtain porous fine particles which are stable in an acidic region and capable of easily carrying hyperfine metallic particle thereon by calcining the particles of the reacted mixture of hydrated titanium oxide and organic acid which has been produced under the specified conditions and thereby forming fine holes. CONSTITUTION: One or more kinds of dibasic acid, tribasic acid or oxy-acid thereof e.g. oxalic acid, succinic acid, tartaric acid and gluconic acid which are regulated to prescribed concn. (preferably 0.5-5.0mol total of organic acid is dissolved in 5-9l pure water) are heated at definite temp. in a range within 50-100°C. The while this soln. is agitated, a titanium tetrachloride aq. soln. is added thereto and titanium tetrachloride is hydrolyzed. Thereby the particles of the reacted mixture of hydrated titanium oxide and organic acid are deposited. Then these particles are calcined at definite temp. range of 200-400°C in the air oxidative atmosphere. Thereby the aimed fine particles are obtained wherein fine holes are formed as the escaping traces of gas resulting from evaporation and decomposition of organic acid and water incorporated in the inside of the particles. COPYRIGHT: (C)1990,JPO&Japio

On the reaction of dithiocarbamates with nitrogen-containing derivates of oxalic acid

Abstract: The action of bisimidochlorides of oxalic acid on dithiocarbamates produces 2-thioxo-3-aryl(alkyl)-4,5-diiminothiazolidines by cycloacylation. The molecular structure of 2-thioxo-3-(4-methoxyphenyl)-4,5-bis(phenylimino)-thiazolidine is confirmed by X-ray crystal structure analysis.