Capacidade de adsorção e dessorção de íons potássio e amônio provenientes da vinhaça pela zeólita natural
Data
2023-01-06
Tipo
Trabalho de conclusão de curso
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Resumo
O efluente da indústria sucroalcooleira, mais conhecido como vinhaça ou vinhoto, tem sido aplicado diretamente no solo agrícola como um fertilizante, podendo causar a contaminação do solo e água subterrânea devido, por exemplo, à sua elevada concentração em matéria orgânica. Além de matéria orgânica, esse efluente contém elevados teores de potássio, nitrogênio e fósforo, que são elementos essenciais para o crescimento e desenvolvimento das plantas. Assim, o presente projeto teve como objetivo testar minerais com elevada capacidade de troca catiônica, como as zeólitas, para retirar os nutrientes presentes na vinhaça para serem utilizados como fertilizantes de liberação lenta. Foram realizados testes experimentais para avaliar a capacidade de retenção de potássio (K+) e amônio (NH4+) por uma amostra de concentrado de zeólitas, primeiro com soluções sintéticas e depois com a vinhaça. As análises químicas e mineralógicas revelaram que o material zeolítico é composto por duas zeólitas (72% de clinoptilolita e 16% de mordenita), além de muscovita (12%). A vinhaça apresenta altos teores de matéria orgânica (8.690 mg L-1), potássio (2.600 mg L-1), cálcio (1.310 mg L-1) e nitrogênio total (900 mg L-1). Foram realizados testes em batelada para analisar os efeitos do tempo e da concentração de amônio e potássio na eficiência de adsorção do material zeolítico. Os resultados revelaram que a eficiência de adsorção de K+ pela zeólita é um pouco maior que de NH4+. Os testes de adsorção com a vinhaça revelaram uma alta afinidade do mineral pelo potássio (devido ao elevado teor desse íon no efluente da vinhaça) – esse elemento, na forma de K2O, aumentou de 1,74% para 4,09% na composição da zeólita após contato com a vinhaça. O teste de dessorção de NH4+ e K+, retidos pelo material zeolítico, realizado em meios aquoso e ácido (para simular as condições do solo tropical) revelou que a zeólita libera os íons adsorvidos de forma lenta em ambas as condições. Em meio aquoso houve uma liberação de cerca de 1% de NH4+ e 0,6% de K+, e em meio ácido de 13% de NH4+ e 22% de K+. Este trabalho revela que as zeólitas podem ser utilizadas como alternativa ao tratamento de efluentes industriais contendo nutrientes (como a vinhaça) e seu uso posterior como fertilizantes de liberação lenta.
The effluent from the sugar and alcohol industry, known as vinasse, has been used directly in agricultural soils as a fertilizer. However, it can cause soil and groundwater contamination. In addition to high levels of organic matter, this effluent contains potassium, nitrogen and phosphorus, which are essential nutrients for plant growth. Thus, the present study aimed to test minerals with high cation exchange capacity, such as zeolites, to remove the nutrients present in vinasse to be used as slow-release fertilizers. Experimental tests were performed to evaluate the potassium (K+) and ammonium (NH +) retention capacity of a sample of zeolite concentrate, first with synthetic solutions and then with vinasse. Mineralogical and chemical analyzes showed that the zeolite material is composed of two zeolites (72% clinoptilolite and 16% mordenite), in addition to muscovite (12%). The vinasse has high levels of organic matter (8,690 mg L-1), potassium (2,600 mg L-1), calcium (1,310 mg L-1) and total nitrogen (900 mg L-1). The batch tests carried out with the synthetic solutions analyzed the effects of time and the concentration of ammonium and potassium in the adsorption efficiency of the zeolite material. The results revealed that the adsorption of K+ ions is slightly higher than that of NH +. Adsorption tests with the vinasse revealed a high affinity of the mineral for potassium (due to the high content of this ion in the effluent) – this element, in the form of K2O, increased from 1.74% to 4.09% in the composition of the zeolite after contact with vinasse. The test of desorption of NH + and K+, retained by the zeolite carried out in aqueous and acidic solution (to simulate tropical soil conditions), revealed that the zeolite releases the adsorbed ions slowly in both conditions. In aqueous solution there was a release of about 1% NH + and 0.6% K+, and in acidic solution of 13% NH + and 22% K+. This study reveals that zeolites can be used as an alternative to the treatment of industrial effluents containing nutrients (such as vinasse) and their subsequent use as slow- release fertilizers.
The effluent from the sugar and alcohol industry, known as vinasse, has been used directly in agricultural soils as a fertilizer. However, it can cause soil and groundwater contamination. In addition to high levels of organic matter, this effluent contains potassium, nitrogen and phosphorus, which are essential nutrients for plant growth. Thus, the present study aimed to test minerals with high cation exchange capacity, such as zeolites, to remove the nutrients present in vinasse to be used as slow-release fertilizers. Experimental tests were performed to evaluate the potassium (K+) and ammonium (NH +) retention capacity of a sample of zeolite concentrate, first with synthetic solutions and then with vinasse. Mineralogical and chemical analyzes showed that the zeolite material is composed of two zeolites (72% clinoptilolite and 16% mordenite), in addition to muscovite (12%). The vinasse has high levels of organic matter (8,690 mg L-1), potassium (2,600 mg L-1), calcium (1,310 mg L-1) and total nitrogen (900 mg L-1). The batch tests carried out with the synthetic solutions analyzed the effects of time and the concentration of ammonium and potassium in the adsorption efficiency of the zeolite material. The results revealed that the adsorption of K+ ions is slightly higher than that of NH +. Adsorption tests with the vinasse revealed a high affinity of the mineral for potassium (due to the high content of this ion in the effluent) – this element, in the form of K2O, increased from 1.74% to 4.09% in the composition of the zeolite after contact with vinasse. The test of desorption of NH + and K+, retained by the zeolite carried out in aqueous and acidic solution (to simulate tropical soil conditions), revealed that the zeolite releases the adsorbed ions slowly in both conditions. In aqueous solution there was a release of about 1% NH + and 0.6% K+, and in acidic solution of 13% NH + and 22% K+. This study reveals that zeolites can be used as an alternative to the treatment of industrial effluents containing nutrients (such as vinasse) and their subsequent use as slow- release fertilizers.