Topic
Oxalic acid
About: Oxalic acid is a research topic. Over the lifetime, 11584 publications have been published within this topic receiving 173263 citations. The topic is also known as: ethanedioic acid & H2ox.
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01 Apr 1983
TL;DR: In this paper, the dissolution rate of magnetite and hermatite at temperatures above 90°C was investigated with three different processes: acid dissolution assisted by chelating agent, reductive dissolution brought about by internal electron transfer between the ligand and the constituent Fe(III) ion complexes, followed by the released of Fe(II), and additional autocatalytic dissolution by the ferrous-carboxylate complexes generated in solution by process (b).
Abstract: Chelating agents, such as ethylenediaminetetraacetic acid (EDTA) and its thermal decomposition products [iminodiacetic acid (IDA), N(2-hydroxyethyl)iminodiacetic acid (HIDA)], and oxalic acid, enhance the dissolution of magnetite and hermatite at temperatures above 90°C. The mechanism involves three different processes: (a) acid dissolution assisted by the chelating agent, (b) reductive dissolution brought about by internal electron transfer between the ligand and the constituent Fe(III) ion complexes, followed by the released of Fe(II), and (c) additional autocatalytic dissolution by the ferrous-carboxylate complexes generated in solution by process (b). Hydrogen peroxide quenches pathway (c) by oxidizing dissolved Fe(II). The rates dissolution in the absence and in the presence of high H 2 O 2 concentrations allow for the evaluation of the relative importance of (a) and (b). Hydrazine greatly accelarated the overall dissolution rates through direct heterogeneous redox interaction with the surface Fe(III) ions. In all cases magnetic is more reactive than hematite. Rate constants are calculated for the various dissolution pathways and, in the case of heterogeneous electron transfer, the values are compared with those for analogous homogeneous reactions.
105 citations
TL;DR: In this paper, the oxalic acid treatment has been used to dealuminate both silica-bound and unbound zeolite {beta} catalysts to very low acidity levels.
Abstract: It is demonstrated that zeolite {beta} and zeolite {beta} containing catalysts can be dealuminated to very low acidity levels using a novel oxalic acid treatment without reducing zeolite integrity. The effect of the oxalic acid treatment has been studied over a wide range of treatment conditions for both silica-bound and unbound zeolite {beta} catalysts. Greater than 90% dealumination is observed with a concomitant reduction in n-hexane-cracking activity as measured by the alpha ({alpha}) test. Removal of framework aluminum occurs via a two-step hyrolysis/chelation mechanism, with the oxalic acid acting both as an acid and as a chelating agent. Framework aluminum removal is accompanied by the formation of internal silanol groups. Water soluble aluminum oxalates are present in the extracted solutions. Silanol groups are annealed with extended oxalic acid treatment. Oxalic acid treatment results in a unique contraction of the zeolite {beta} lattice structure not observed for mineral acid treated or steamed zeolite {beta} catalysts. 15 refs., 11 figs., 5 tabs.
105 citations
TL;DR: The adsorption and photoreaction of oxalic acid on the surface of anatase and rutile TiO2 nanoparticles have been studied using a combined experimental and theoretical approach and can be described as a mixture of adsorbed water and oxAlic acid molecules.
Abstract: The adsorption and photoreaction of oxalic acid on the surface of anatase and rutile TiO2 nanoparticles have been studied using a combined experimental and theoretical approach. In the dark, the experimental adsorption reaches an equilibrium state that can be described as a mixture of adsorbed water and oxalic acid molecules, with the latter forming two different surface complexes on anatase and one on rutile particles. When the system is subsequently illuminated with UV(A) light, the surface becomes enriched with absorbed oxalic acid, which replaces photo-desorbed water molecules, and one of the adsorbed oxalic acid structures on anatase is favoured over the other.
105 citations
TL;DR: The use of ascorbic acid or citric acid as reductants in acidic leaching appears to be effective in the simultaneous leaching and further recovery of zinc and manganese from spent alkaline and zinc-carbon battery powders.
105 citations
TL;DR: In this article, the Starbon material was used as a support for palladium catalysts for glycerol-acetic and oxalic acid mixtures, achieving selectivities to mono-, di-and triacetylated glycerols.
Abstract: New polysaccharide based solid acids are excellent catalysts for selective chemical transformations of glycerol. Reasonable selectivities to mono-, di- and triacetylated glycerols can be obtained by controlled microwave activation of glycerol–acetic and solid acid mixtures. Etherifications of glycerol using a range of alcohols have also been achieved and with a degree of selectivity to both 1- and 2-positions. The use of the Starbon® material as a support for palladium further extends the range of heterogeneous catalysed chemistry to the selective oxidations of glycerol to both glycolic and oxalic acids. In all of the reactions, the catalysts can be easily recovered and reused with only a small loss in activity.
105 citations