Showing papers on "Oxalic acid published in 1982"

De-icing chemicals and their preparation from polysaccharide sources

Abstract: Deicing chemicals intended primarily for decing pavement such as roads, bridges, and runways are prepared from polysaccharide sources (e.g., waste products such as sawdust) by reaction at a pressure of less than 600 psi and a temperature less than 200° C. with a treating agent comprising alkali metal carbonates or bicarbonates or a mixture thereof and excess oxygen in the presence of water followed by the removal of oxalate and the treating agent. The reaction produces a liquid or a liquid/solid reaction product wherein the liquid contains the deicing chemical and the solid comprises a valuable pulp by-product. Calcium oxide or calcium hydroxide may be added to reduce the pressure resulting from the formation of large amounts of carbon dioxide during the reaction process and to aid in the removal of any oxalic acid formed during the reaction process. The deicing chemicals are impure mixtures of alkali metal salts of lower carboxylic acids substantially free of the alkali metal salt of oxalic acid, carbonic acid and of other organic compounds. The deicing chemicals are intended to be a substitute for the inorganic chloride salts (e.g, sodium chloride) commonly used for deicing highways.

Modifying glass bead surfaces

Abstract: A method of modifying the surface of hollow glass beads including the step of treating the beads with a solution containing at least one of an organic acid selected from beta-hydroxy acids, oxalic acid and ethylene diamine tetraacetic acid, and a salt of said organic acid.

Effect of vitamin B6 administration on elevated plasma oxalic acid levels in haemodialysed patients.

Abstract: Accumulation of oxalic acid resulting in elevated plasma levels is a common finding in uraemic patients. Since vitamin B6 is an important coenzyme in oxalic acid metabolism the influence of vitamin B6 administration on plasma oxalic acid levels was investigated. Vitamin B6 was administered to eight chronic haemodialysis patients with secondary hyperoxalaemia. Mean plasma oxalic acid concentration decreased from 149.5 +/- 67 mumol/l to 99.0 +/- 36.4 mumol/l within 2 weeks and to 93.8 +/- 33.1 mumol/l after 4 weeks of pyridoxine treatment (P less than 0.01) the mean reduction being 46% (32.0-56.1%). The decrease in plasma oxalic acid levels was most pronounced in patients with the highest pretreatment values. Two patients who received pyridoxine therapy prior to the beginning of the study had low initial values of plasma oxalic acid concentrations and showed no further decline.

Electrochemical organic synthesis

Abstract: The present invention relates to an electrochemical process for synthesizing carboxylic acids by reduction of gaseous oxides of carbon in which a gas transfer electrode is used as the cathode The gas transfer electrodes are preferably used as hydrophobic gas transfer electrodes In carrying out the process it is particularly preferred to use porous, hydrophobic gas transfer electrodes made from an electrocatalyst eg carbon, bound in a polymer such as polyethylene or polytetrafluoroethylene (PTFE) In the case of some reactions another electro-catalyst may be added to the carbon/polymer mixture The process is particularly suited to producing acids such as formic acid and oxalic acid

Effect of ozone and sodium hydroxide treatments on some chemical characteristics of cotton straw

Abstract: Cotton straw (CS) was treated with ozone or sodium hydroxide, and the effect of treatments on the organic acid and monosaccharide composition and on the chromat-ographic characteristics of alkali lignin was studied. The concentrations of formic and acetic acids in the ozonised CS were 3.98 and 1.36 g 100 g−1 organic matter (OM) respectively. Oxalic acid was not detected. A high content of uronic acids (9.78 g 100 g−1 OM) was found in CS. The overall decrease in total monosaccharides in the ozonated CS was very small (5%) with the matrix constituents being principally affected. The 8% sodium hydroxide treatment exerted a very limited effect on the composition of CS cell walls. Ozonation increased the content of soluble carbohydrates from 9.2 to 21.8%; this was contributed mainly by the hemicellulose fraction. Alkali lignin was extracted from CS and was fractionated by gel chromatography. The elution pattern of alkali lignin was very similar for the treated and untreated materials. The three peaks coincided at an average mol. wt of 40 000, as judged from the use of dextran standards.

Factors affecting endogenous oxalate synthesis and its excretion in feces and urine in rats.

Abstract: It has been observed that the feces as well as urine of rats fed diets supplemented with 3% glycine and 5.2% hydroxyproline contain unexpectedly high amounts of endogenously formed oxalate. That intestinal microorganisms do not synthesize significant amounts of oxalate was indicated by the findings that oral tetracycline had no effect on oxalate excretion and that germ-free rats excreted more oxalate than conventional rats. Since little intraperitoneally injected [14C] oxalate appeared in the feces, and rat intestinal mucosa homogenates were found to produce oxalate from a variety of precursors of which glyoxylic acid was far the most important, it is probable that the intestinal mucosa may be an important source of fecal oxalate observed in these studies. Ninety percent of weanling rats fed complete diets supplemented with glycine and hydroxyproline developed urinary stones in 38 days. It has been concluded that in the treatment of patients with histories of calcium oxalate urolithiasis, more concern than is commonly shown should be directed towards the feeding of diets high in precursors of endogenous oxalate synthesis.

Chemical evolution 40. Clay-mediated oxidation of diaminomaleonitrile.

Abstract: The previously reported inhibition of the oligomerization of HCN by montmorillonite clays was investigated. The inhibition is due to the oxidation of diaminomaleonitrile (DAMN) by the Fe3+ in the clay lattice. Fe2+ and oxalic acid were shown to be the reaction products. From these reaction products and the previous report that two equivalents of HCN are formed per equivalent ofDAMN, it was established that diiminosuccinonitrile (DISN) is the initial reaction product, which is rapidly hydrolyzed to oxalic acid and HCN. The same oxidative transformations are effected by Fe3+ bound to Dowex 50, Fe3+ in solution and Ni(NH3)62+. The rate of reaction of DAMN decreased in the order Fe3+ > Fe3+-Dowex > montmorillonite, indicating no catalytic role for the clay in the oxidation of DAMN. Little reaction of DAMN was observed with montmorillonite in which the bulk of the iron was in the Fe2+ oxidation state. The possible significance of these redox reactions to chemical evolution is discussed.

Role of Organic and Inorganic Reactions in Development of Secondary Porosity in Sandstones: ABSTRACT

Abstract: The development of secondary porosity in many sandstones is the result of aluminosilicate and/or carbonate dissolution. The dissolution of aluminosilicates and creation of secondary porosity is a problem of aluminum mobility. Our experimental data demonstrate that it is possible to increase significantly the mobility of aluminum and to transport it as an organic complex in aliphatic acid solutions. The same aliphatic acid solutions have the capability of destroying carbonate cements and debris. Carothers and Kaharka have shown that concentrations of aliphatic acid anions range up to 5,000 ppm over the temperature range 80 to 200°C in some oil field formation waters. Our experiments show that acetic acid solutions at the same concentrations and over the same temperature range can increase the solubility of aluminum by a half an order of magnitude, whereas oxalic acid solutions increase the solubility of aluminum by an order of magnitude. The textural relations observed in the experiments are identical to those observed in sandstones containing secondary porosity as a result of aluminosilicate dissolution. A natural consequence of the burial of sedimentary prisms is the maturation of organic material. These maturation reactions result in the evolution of significant amounts of organic acids and carbon dioxide. The experiments suggest that the development of secondary porosity in a sandstone as a result of aluminosilicate or carbonate dissolution is the natural consequence of the interaction of organic and inorganic reactions during progressive diagenesis. The degree to which secondary porosity develops depends on the ratio of organic to inorganic matter, the sequence, rates and magnitude of diagenetic reactions, fluid flux, and sand/shale geometry. End_of_Article - Last_Page 635------------

Process for stripping uranium from an alkyl pyrophosphoric acid

Abstract: A process is described for the recovery of tetravalent uranium from wet-process phosphoric acid utilizing an alkyl pyrophosphoric acid extractant or the like. After extracting the tetravalent uranium from wet-process acid, iron is stripped from the pregnant extractant into an oxalic acid stripping solution and then the tetravalent uranium is stripped from the pregnant extractant into an oxalate stripping solution. The oxalate stripping solution is an aqueous solution of an alkali metal or ammonium oxalate. The barren extractant is recycled for contacting with fresh wet-process acid. The uranium is oxidized and then precipitated in the oxalate stripping solution. The precipitated solids are separated from the solution, and the uranium is dried to a UO3 product.

Process for the production of glycollic acid esters

Abstract: In a process for producing a glycollic acid ester by the vapor phase catalytic hydrogenation of an oxalic acid diester in the presence of a catalyst and hydrogen gas, the improvement wherein the oxalic acid diester in the vaporous state is contacted with hydrogen gas in the presence of a catalyst composed of Ag or Pd supported on a solid carrier at a temperature of from about 120° C. to about 300° C.

Simple, reliable chromatographic measurement of oxalate in urine.

Abstract: In this assay for oxalate in urine, oxalate is adsorbed from the urine onto graphitized carbon black (Carbopack B). After desorption and removal of the solvent, oxalic acid is gas-chromatographically measured after being derivatized with BF3/methanol. Chromatography is on Carbopack B/polyethylene glycol (Mr 20000), 93.7/6.3 by weight. The lower limit of detection of urinary oxalate is about 3 mg/L (CV less than or equal to 3.6%). A series of oxalate determinations in 24-h urine samples of 15 subjects gave a mean of 47.1 (SD 15.4) mg/24 h, with an analytical recovery of 97.4% (SD 3.0%, range 93.6-102.4%). Total analysis time for one sample is about 2 h.

Spectrophotometric Determination of Silicic Acid by Flow Injection Analysis

Abstract: Flow injection analysis (FIA) was developed for the spectrophotometric determination of silicic acid based on the formation of a yellow molybdosilicic acid (yellow method) and a heteropoly blue complex (blue method). In the yellow method, silicic acid in the concentration range of 2 to 100 ppm (SiO2) could be determined at a sampling rate of 60 samples/h. The FIA system was modified to determine silicic acid in the presence of orthophosphate. Oxalic acid was used for the decomposition of molybdophosphoric acid. The modified system was employed for the rapid and selective determination of silicic acid in well and river waters. In the blue method, ascorbic acid was used to reduce the yellow molybdosilicic acid to a heteropoly blue complex. Silicic acid in the concentration range of 0.02 to 1.0 ppm (SiO2) could be determined at a sampling rate of 40 samples/h. The FIA system was also modified to determine silicic acid in the presence of orthophosphate. The reducing agent was introduced after molybdophosphori...

Photograft Copolymerization of Methyl Methacrylate on Cellulose and Oxycellulose Using Oxalic Acid-Permanganate Redox Initiator in a Limited Aqueous System

Abstract: Graft copolymerizations of methyl methacrylate (MMA) on cellulose and oxycellulose were studied mostly under photo-activation with visible light using oxalic acid/KMnO4 redox initiator in a limited aqueous system. Polymerization in the dark (40-60°C) produced little graft copolymer, while that in the light at 32° C produced significant or efficient grafting at reasonable rates. Cellulose, modified to degrees of oxidation corresponding to copper number 20–35, produced optimum grafting. Percent grating and grafting efficiency under different sets of conditions were studied and compared, and the mechanism of polymerization and graft copolymer formation discussed. Generation of grafting sites (radical centers) on cellulose/ oxycellulose was consequential only in the presence of light. Generally higher percent grafting and grafting efficiency in oxycellulose systems (as against cellulose systems) appear to be due to more easy and effective generation of radical sites on oxycellulose through oxidation ...

Recovery of yttrium and europium from contaminated solutions

Abstract: A procedure is given for recovering yttrium and europium from phosphors or solutions which have become contaminated. An acid solution containing the yttrium, europium and impurities is passed through a cation resin exchange column until there is no longer a difference between the contaminated and effluent liquids. Yttrium and europium are then stripped from the resin exchange column using a concentrated hydrochloric acid solution. The hydrochloric acid solution containing the yttrium and europium is heated with oxalic acid to produce yttrium and europium oxalate and the oxalate is fired to produce yttrium and europium oxide.

Decomposition of oxalic acid with nitric acid

Abstract: Oxalic acid or oxalate is widely used as a precipitant and a detergent in the field of nuclear energy. The present work aimed at developing a method of decomposing oxalic acid with HNO3 in the presence of Mn2+ ion. The use of Mn2+ ion as low as 10−3 mol/l facilitated the complete decomposition of oxalic acid, and the acidity of the resulting solution became as low as 0.1 eq/1 under the optimum conditions. The decomposition of oxalic acid is a first order reaction and proceeds at temperatures above 80°C; the activation energy of the reaction is 18.6 kcal/mol. This decomposition method is applicable to the dissolution of an oxalate precipitate.

Regeneration of used denitration catalyst

Abstract: PURPOSE:To regenerate used V2O3-TiO2 type denitration catalysts to the catalysts having the activity equal to that of fresh catalysts by removing the materials stuck on said catalysts with water or acids then coating a V2O3-TiO2 slurry having viscosity within a specific range and drying and calcining these. CONSTITUTION:Denitration catalysts for waste gases consisting of 80-95wt% TiO2, 20-5% V2O3 or V2O3 substituted partly with WO3 and MoO3 are deposited with compds. of alkali metals and alkaline earth metals or dust, etc. on their surfaces upon long-term use, on account of which their activity degrades and such catalysts require replacement. These used catalysts are quickly washed with water or a dilute aq. son. of sulfuric acid, nitric acid, hydrochloric acid, etc., whereby they are removed of stuck materials. When the pollution by dust or poisonous materials is heavy, these are further washed with a heated aq. oxalic acid soln. Thereafter, an SiO2 slurry of 0.3-2.0 poise viscosity contg. V compds. or further compds. of W or Mo is coated thereon, after which the catalysts are dried and are calcined.

Process for the production of ethylene glycol and/or glycollic acid esters, and catalyst therefor

Abstract: In a process for producing ethylene glycol and/or a glycollic acid ester by the vapor phase catalytic hydrogenation of an oxalic acid diester in the presence of a catalyst and hydrogen gas, the improvement wherein the catalyst has the following composition formula CuMo.sub.k Ba.sub.p O.sub.q wherein k, p and q represent gram-atoms of Mo, Ba and O, respectively, per gram-atom of Cu, k is a number of from 0 to 3, p is a number of from 0 to 6, and q is a number determined depending upon the atomic valence and gram-atoms of Cu, Mo and Ba, provided that k and p are not zero at the same time; and the aforesaid catalyst.