Desenvolvimento de metodologia para extração de substâncias húmicas de turfas utilizando se hidróxido de potássio
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Data
1998
Autores
Rosa, André Henrique [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Substâncias Húmicas (SH), extraídas de turfa sob diferentes condições foram caracterizadas com o objetivo de se desenvolver nova metodologia de extração com elevado rendimento, baixo teor de cinzas e sem grandes alterações estruturais. Parâmetros como: tempo, temperatura, atmosfera de extração, razão solo/extrator, granulometria do solo, extrator e sua concentração foram avaliados e mostraram ter grande influência no processo. Pelos estudos feitos e resultados obtidos pode-se concluir para a amostra estudada que: 1 - a extração alcalina das substâncias húmicas utilizando-se hidróxido de potássio aumenta o rendimento e diminui o teor de contaminantes inorgânicos co-extraídos em relação ao procedimento utilizando hidróxido de sódio; 2 - a concentração do extrator influencia muito no rendimento, teor de cinzas, razão E4/E6, razão AH/AF e composição elementar das substâncias húmicas extraídas; 3 - 4 horas de extração são suficientes para extrair praticamente toda matéria orgânica presente na amostra; 4 - a razão solo/extrator não exerce influência no teor de matéria orgânica extraída, entretanto, a diminuição dessa razão eleva o teor de contaminantes inorgânicos no extrato húmico; 5 - espectros na região do infravermelho e visível mostraram que o aumento da temperatura de extração causa mudanças estruturais nos ácidos húmico e fúlvico...
Humic Substances (HS), extracted from the peat under different conditions were characterised with the aim of developing a methodology of extraction with high yields, low contents of ashes and without big structural alterations. Parameters such as: time, temperature, extraction atmosphere, soil/extractor ratios, soil granulemetry, extractor and its concentration were evaluated and showed to have great influence on the process. By the studies done and results obtained we can conclude to the studied sample that: 1. the alkaline extraction from the humic substances using potassium hydroxide increase the yields and reduce the contents of inorganic contaminator co-extracted in relation to the procedure that uses sodium hydroxide; 2. the concentration of the extractor influences very much on the yields, contents of ashes, E4/E6 ratios, AH/AF ratios and elementary composition of the extracted humic substances; 3. four hours of extraction are enough to extract almost all the organic material present in the sample; 4. the soil/extractor ratios does not exert any influence on the contents of the extracted organic material, however, the decrease of this ratio increases the contents of inorganic contaminator in the humic extract; 5. spectres in the region of the infrared and visible showed that the increase of temperature of extraction provokes structural changes in the humic and fulvic acids. It was also verified that the reduction of the contents of humic acid and elevation of the fulvic acid extracted with the increase of temperature; 6. the nitrogen atmosphere minimises the oxidation of the humic and fulvic acids during the extraction. The increase in time of extraction of the humic substances in the absence of nitrogen favours the oxidative processes; ...(Complete abstract, click electronic access below)
Humic Substances (HS), extracted from the peat under different conditions were characterised with the aim of developing a methodology of extraction with high yields, low contents of ashes and without big structural alterations. Parameters such as: time, temperature, extraction atmosphere, soil/extractor ratios, soil granulemetry, extractor and its concentration were evaluated and showed to have great influence on the process. By the studies done and results obtained we can conclude to the studied sample that: 1. the alkaline extraction from the humic substances using potassium hydroxide increase the yields and reduce the contents of inorganic contaminator co-extracted in relation to the procedure that uses sodium hydroxide; 2. the concentration of the extractor influences very much on the yields, contents of ashes, E4/E6 ratios, AH/AF ratios and elementary composition of the extracted humic substances; 3. four hours of extraction are enough to extract almost all the organic material present in the sample; 4. the soil/extractor ratios does not exert any influence on the contents of the extracted organic material, however, the decrease of this ratio increases the contents of inorganic contaminator in the humic extract; 5. spectres in the region of the infrared and visible showed that the increase of temperature of extraction provokes structural changes in the humic and fulvic acids. It was also verified that the reduction of the contents of humic acid and elevation of the fulvic acid extracted with the increase of temperature; 6. the nitrogen atmosphere minimises the oxidation of the humic and fulvic acids during the extraction. The increase in time of extraction of the humic substances in the absence of nitrogen favours the oxidative processes; ...(Complete abstract, click electronic access below)
Descrição
Palavras-chave
Extração (Quimica) - Turfa, Extração (Quimica) - Humus, Substâncias húmicas, Análise de traços, Quimica analitica, Humic substance, Peat
Como citar
ROSA, André Henrique. Desenvolvimento de metodologia para extração de substâncias húmicas de turfas utilizando se hidróxido de potássio. 1998. 99 f. Dissertação (mestrado) Universidade Estadual Paulista, Instituto de Química, 1998.