Ácidos orgânicos de baixa massa molar em solos e materiais orgânicos

Determination of organic acids in soils and organic materials is important due to the important role they play in improving the soil's physical, chemical and microbiological conditions. This study identified and quantified low molecular weight organic acids (LMWOA) in soils (dystroferric Red Latosol, dystrophic Red-Yellow Latosol and Quartzarenic Neosol) and organic materials (cow, pig, chicken, quail and horse manures, sawdust, coconut fiber, pine bark, coffee husks, biochar, organic substrate, sewage sludges 1 and 2, garbage compost, pig slurry compost). The following acids were identified: acetic, citric, D-malic, formic, fumaric, maleic, malonic, oxalic, quinic, shikimic, succinic and tartaric.

Obtenção de fotocatalisadores magnéticos a partir de resíduos industriais e TiO2 para a degradação de contaminantes orgânicos

In this work, magnetic photocatalysts were synthesized containing differents levels of TiO2 (40, 60 e 80%) supported at the supporter of C/LV, forming the photocatalysts 40, 60, 80Ti/C/LV, using tar pitch as carbon (C) source and red mud (LV) as iron source. The prepared magnetic photocatalysts and TiO2 were used to degrade the Remazol Black textile dye (PR5) and the organic material present in samples of a textile dye effluent. The characterization of photocatalysts by Raman, X-Ray Diffraction, Transmission Electron Micoscope and Scanning, Energy Dispersive X-ray Spectrometry, Termogravimetry and Elemental Analysis, confirms the presence of carbon and magnetite in support C/LV and the presence of TiO2 in prepared photocatalysts. The photocatalytic reactions with TiO2 were analyzed by different experimental conditions, such as: mass of TiO2 (30-240 mg), solution pH (2-10), light intensity (0.871 and 1.20 mWcm-2), type of radiation (UV and sunlight-1.420 mWcm-2), radiation incidence area (44.2 to 143.1 cm2) and dissolved oxygen (OD, 1.9 and 7.6 mg L- 1). Results showed that reactions with the following conditions: 220 mg of TiO2, pH 10, solar radiation, 7.6 mg L-1 of OD and an incidence area of radiation of 143.1 cm2 showed the best results for degradation of PR5 dye. Photocatalytic reactions with magnetic photocatalysts for degrading PR5 shows that efficiency increases with TiO2 content in the C/LV support, where, above 60% of TiO2, there was not significant increase in reaction velocity. In addition, solar radiation has proved to be advantageous for photocatalytic reactions. In order to verify the presence of a non-magnetic fraction in the photocatalyst 60Ti/C/LV0, magnetic separation was proceeded. The characterizations of the magnetic (FM) and nonmagnetic (NMF) fraction confirmed that about 25% of TiO2 did not fixed in 60Ti/C/LV photocatalyst. Results of photocatalytic reactions with FM and FNM showed that both phases have photocatalytic activity for degradation of PR5. The reactions executed for the degradation of organic matter present in the actual sample of textile effluent showed that TiO2 and magnetic photocatalyst 60Ti/C/ LV have better results for color removal (85 to 35%), soluble solids ( 11 and 3%), DQO (90 and 86%) and turbidity (94 and 11%) than the treatment done by the textile industry. Sedimentation kinetics tests in presence of a magnet showed that photocatalysts are separated faster from aqueous environment than pure TiO2. Obtained results showed that magnetic photocatalysts have excellent photocatalytic activity and can be separated from the reaction environment on a simple and quick way when a magnetic field is applied.

Solubilização de fontes alternativas de potássio pelos ácidos húmicos, cítrico e casca de café

This study was to evaluate the solubility of nepheline syenite rocks and glauconite as alternative sources of K by organic humic acid arrays, citrus and coffee pods at various times from 0 to 180 days of incubation. The experiment was conducted in the fertility laboratory in the Department of Soil Science at the Federal University of Lavras in a completely randomized design with 90 treatments and 3 replications. The treatments were arranged in a factorial arrangement (2 x 3 x 7 + 3), 2 nepheline syenite rocks and glauconite incubated with water and 3 matrix organic humic acid, citric acid and coffee husk in six different incubation times of 0, 7, 15, 30, 75, 120 and 180 days, incubation were performed with the three above-mentioned organic matrix in increasing doses of 0, 1, 2, 5 and 10% humic acids and citric 0, 5, 10 20 and 40% for coffee husk. We evaluated the K2O content by different extractants soluble in 2% citric acid and water all treatments at all incubation times quoted above. Incubation and the application of organic matrix rocks nepheline syenite and generally glauconite provided a significant increase in solubility of K of the rocks studied in this work. Among the organic matrix has been observed that the coffee husk which provided the greatest release of K2O in both rocks mainly into the extractor 2% citric acid showed that the most efficient extraction K2O in all treatments.

Síntese do complexo ferro (III) com ácido pirazina tetracarboxílico e aplicação como catalisador em reação fenton

The amount of waste generated by industries has increased gradually in recent years. The proper disposal of residues has been an area of study of many researchers. Several organic compounds are considered potential contaminants of natural waters due to their high toxicity, difficult natural degradation and long persistence in the environment. Ways of recovery and reutilization as well as concepts that minimize the generation of wastes have been increasing widely. Organometallic compound of pyrazine carboxylic acid has proven to be of great interest in many areas. Herein, we studied the use of pyrazine tetracarboxylic acid ligand for complex formation with iron (Fe). The binder (C 8H4N2O8) was synthetized with the addition of Fe (complex) and tested as a catalyst in oxidation reactions of the organic model compound methylene blue (MB). Tetramethyl pyrazine was used in the synthesis, which was oxidized with potassium permanganate in order to form the ligand. The ligand (C 8H4N2O8) was then characterized to validate its formation. For the complex solution, it was used (C 8H4N2O8) and Fe (NO3)3.9H2O 0,01molL-1. After preliminary tests, it was found that the best ratio of Fe and the ligand was 2: 1. Through the oxidation tests, it could be seen that the complex has great potential for the degradation of different concentrations of MB. During only 20 minutes of reaction, approximately 60% of MB 500 mgL -1 was oxidized. The use of the complex was found to be an attractive alternative for oxidation of effluents with high organic compounds levels and contributes to the minimization of organic contaminants hazards in the environment.