Avaliação de desempenho do uso de cascas de abacaxi e laranja para remoção de Cd e Pb em água

Abstract

Os metais pesados são tóxicos ao ser humano e a biota, eles compõem um dos problemas atuais nos efluentes e resíduos das indústrias químicas que precisam tratá-los antes de despejá-los nos cursos d’água ou rede coletora, porém o tratamento de metais ainda é algo caro e que precisa ser aprimorado ou a utilização de métodos mais baratos. O tratamento nas ETEs não são tão eficazes e não retiram todos os metais presentes. O abacaxi e a laranja são frutas cultivadas e consumidas em larga escala no Brasil e no mundo, porém suas cascas não são comumente usadas e viram rejeitos, pensando nisso, foram escolhidas as cascas destas frutas para serem reutilizadas para o tratamento de água e efluentes. Este trabalho teve como objetivo testar uma metodologia já usada em pesquisas anteriores, para descontaminação de porções de água com metais chumbo e cádmio presente nestas, empregando o uso de farinha de cascas de abacaxi e laranja para que ocorra a adsorção, que consiste na interação superficial de duas moléculas, íons e átomos, desses metais nas cascas de frutas através da pectina, uma substância presente nas cascas de frutas, principalmente em frutas cítricas. Para a preparação das amostras foram utilizadas soluções padrão de metais da marca MERCK. As amostras foram feitas em triplicatas para melhor certeza dos resultados. As concentrações finais dos metais presente nas amostras foram analisadas por espectrometria de emissão atômica com plasma indutivamente acoplado (ICP/OES), por ser uma técnica multielementar bastante utilizada para determinação de poluentes metálicos. A adsorção variou entre 13,79 e 22,03%. Houve uma diferença significativa entre a adsorção do cádmio e chumbo. O método pode futuramente ser aprimorado mudando alguns parâmetros para maior adsorção.

Heavy metals are toxic to humans and wildlife, and they make up one of the current problems in the effluents and wastes from chemical industries, which need to treat them before discharging into water bodies or sewage systems. However, metal treatment is still expensive and needs to be improved, or cheaper methods need to be used. Treatment in wastewater treatment plants is not very effective and does not remove all the metals present. Pineapple and orange are fruits that are cultivated and consumed on a large scale in Brazil and worldwide; however, their peels are not commonly used and become waste. With this in mind, the peels of these fruits were chosen to be reused for water and effluent treatment. This study aimed to test a methodology already used in previous research for the decontamination of water portions containing lead and cadmium metals, employing the use of pineapple and orange peel flour so that adsorption occurs, which consists of the surface interaction of two molecules, ions, and atoms of these metals on the fruit peels through pectin, a substance present in fruit peels, especially in citrus fruits. For the preparation of the samples, standard metal solutions from the brand MERCK were used. The samples were made in triplicate for better certainty of the results. Heavy metals are toxic to humans and biota. They are one of the current problems in the effluents and waste from chemical industries, which need to be treated before being discharged into waterways or sewers. However, metal treatment is still expensive and needs improvement or the use of cheaper methods. Treatment in wastewater treatment plants is not very effective and does not remove all the metals present. Pineapple and orange are fruits cultivated and consumed on a large scale in Brazil and worldwide, but their peels are not commonly used and become waste. With this in mind, the peels of these fruits were chosen to be reused for water and effluent treatment. This work aimed to test a methodology already used in previous research for the decontamination of water samples containing lead and cadmium, employing the use of pineapple and orange peel flour to induce adsorption. Adsorption consists of the surface interaction of two molecules, ions, and atoms of these metals on the fruit peels through pectin, a substance present in fruit peels, mainly citrus fruits. Standard metal solutions from MERCK were used to prepare the samples. Samples were prepared in triplicate for better accuracy of results. The final concentrations of the metals present in the samples were analyzed by inductively coupled plasma atomic emission spectrometry (ICP/OES), a multi-element technique widely used for the determination of metallic pollutants. Adsorption ranged from 13.79% to 22.03%. There was a significant difference between the adsorption of cadmium and lead. The method can be improved in the future by changing some parameters to increase adsorption.