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.

Interaction of metal hydrous oxides with chelating agents. 7. Hematite-oxalic acid and -citric acid systems

Abstract: Etudes de l'adsorption des ions oxalate et citrate sur des particules spheriques colloidales d'hematite et de leur influence sur l'elimination du fer a partir de celles-ci, en fonction de la concentration du solute, du pH et de la temperature

Study of the copper leaching in the wet oxidation of phenol with CuO-based catalysts: Causes and effects

Abstract: Catalytic wet oxidation of phenol as a model pollutant has been performed in a three phase fixed-bed reactor (FBR) by using a commercial catalyst based on copper oxide in order to analyze the variables affecting significantly the copper leaching. It has been found that temperature has an almost negligible influence in the range studied (70–160 °C). On the contrary, an important effect of the pH value was noticed. The copper leaching reduces when the pH of the solution fed to the reactor increases, being almost negligible at pH ≥ 5. Moreover, the composition of the reaction media also influences the leaching. Higher copper concentrations than those expected by the effect of the acid aqueous media have been measured in the reactor effluent when phenol, catechol, hydroquinone, p -benzoquinone and maleic acid are present in the reaction media. On the contrary, oxalic acid has a negative influence on the leaching, since it captures the copper in solution to form copper oxalate which precipitates on the catalyst surface. For a previously acidified medium, the acetic and formic acids do not have any other effect on the copper leaching. It has been also demonstrated that as copper in solution decreases, so does phenol conversion, because the homogeneous catalysis contributes significantly to the oxidation reactions even in fixed-bed reactors.

Effect of Dissolved Cobalt(II) on the Ozonation of Oxalic Acid

Abstract: Cobalt(II) was examined as an ozonation catalyst. Laboratory-scale batch ozonation experiments were run at near-neutral pH and 24 °C. A hydroxyl radical probe compound, p-chlorobenzoic acid (pCBA), was also included in the solution matrix. Batch experiments showed that trace amounts of cobalt(II) accelerated the ozonation of oxalate. The rate of oxalate removal increased with decreasing pH from pH 6.7 to pH 5.3. The presence of cobalt(II) also increased the removal rate of pCBA indicating that the generation of hydroxyl radicals are byproducts of cobalt(II)-catalyzed ozonation of oxalate. It is proposed that the first step in the catalytic ozonation reaction pathway is the formation of a cobalt(II)−oxalate complex. Cobalt(II) oxalate is then oxidized by ozone to form cobalt(III) oxalate. The catalytic cycle is completed with decomposition of the cobalt(III) complex to form cobalt(II) and an oxalate radical. Assuming that cobalt, oxalate, and water were in equilibrium, the second-order reaction rate consta...