AVALIAÇÃO DE METODOLOGIAS PARA A CARACTERIZAÇÃO QUÍMICA DA VINHAÇA EM FUNÇÃO DO TEMPO DE ARMAZENAMENTO

Abstract

The objective of this work was to evaluate analytical methods of efficient wet digestion by the official analysis method, of a mixture of nitric acid and perchloric acid (HNO3 + HClO4), for the analysis of vinasse and also verify the effects of nutrients on the stored vinasse. You Compared analytical methods were: 1) Nitroperchloric (HNO3), 2) Nitric (HNO3); 3) Hydrochloric + Hydrogen Peroxide (HCl+ H2O2); 4) Sulfuric + Hydrogen Peroxide (H2SO4 + H2O2) and 5) Solubilization with 1 molar hydrochloric acid (HCl 1 mol/L-1). Were certain phosphorus, potassium, calcium, magnesium and sulphur, over different periods of storage, these nutrients being analyzed with 5, 30, 90 and 150 days of storage, to check the behavior of these nutrients over time that is stored in laboratory conditions. The efficiency of the methods was evaluated by comparing the results of the nitroperchloric method obtained for each nutrient with the results obtained for the others methods. The results showed that Nitric (HNO3) and Hydrochloric + Peroxide digestions of Hydrogen (HCl+ H2O2), showed good to excellent precision equivalent to digestion Nitroperchloric (HNO3), for the analyzed nutrients. The Acid Solubilization Method 1 molar hydrochloric acid (HCl 1 mol/L-1) showed low accuracy and did not show efficiency expected for quantification of any analyzed nutrient. With the exception of potassium contents (K), all other nutrients analyzed in the work reduced at the end of the days of stillage storage.