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.

Comparison of the photocatalytic efficiency of TiO2, iron oxides and mixed Ti(IV)Fe(III) oxides: photodegradation of oligocarboxylic acids

Abstract: Comparative photo-oxidations of three oligocarboxylic acids, i.e. oxalic acid, EDTA and malonic acid, were performed with different catalysts, i.e. TiO 2 (Degussa P-25), α-Fe 2 O 3 , γ-Fe 3 O 4 and two samples of mixed Fe(III)Ti(IV) oxides containing 0.5 wt.% and 5 wt.% Fe respectively. Different irradiation wavelengths were used. It was found that the photocatalytic efficiency depends mainly on the physicochemical properties of the catalyst, the irradiation wavelength, and the redox potential and adsorption ability of the substrate. The effect of surface complexes formed between the oxide and the organic compound was analysed. TiO 2 was found to be the best catalyst. The relative utility and stability of iron oxides and mixed FeTi oxides is discussed.

Solubilization of inorganic phosphates and plant growth promotion by Aspergillus niger

Abstract: Two of 187 fungal isolates (Aspergillus niger 1B and 6A) displaying superior phosphate (P) solubilization and hydrolytic enzyme secretion were studied using P forms of calcium (Ca-P), iron (Fe-P), and aluminum (Al-P). Phosphate solubilization in a sucrose-basal salt (SB) broth was increased and pH decreased by both isolates. In Ca-P medium, solubilization for 6A was approximately 322 μg P mL−1 and pH decreased by 4.2 units to 2.3 in 72 h. However, when pH value of the SB broth was lowered to 2.5 using HCl, 65.3 ± 0.4 μg mL−1 of P was released from Ca-P, whereas trace amounts of P were released from Fe-P and Al-P. Both isolates displayed enhanced Al-P solubilization using NH4Cl rather than KNO3 as the N source; final pH values were not significantly different. With Ca-P, gluconic acid was predominantly produced by 1B and 6A, whereas oxalic acid predominated with Fe-P and Al-P. Addition of gluconic acid (final concentration of 8.5 μmol mL−1) to Ca-P-supplemented SB lowered pH (2.9) and solubilized phosphate (146.0 ± 1.0 μg mL−1). Similarly, addition of oxalic acid (final concentration 6.6 μmol mL−1) to Ca-P- and Fe-P-amended media solubilized P (60.2 ± 0.9 and 21.6 ± 2.1 μg mL−1, respectively), although these quantities were significantly lower than those detected in unamended SB. The presence of unidentified P solubilized compound(s) in the dialyzed (MW>500) supernatant warrants further study. In pot experiments, significant increases in plant (Brassica chinensis Linn.) dry weight and N and P contents were observed with the addition of isolate 6A, when a small amount of organic fertilizer together with either rock phosphate (South African apatite) or Ca-P served as the main P sources.