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Recebido em 14/11/12; aceito em 13/5/13; publicado na web em 17/7/13 This study evaluated the adsorption capacity of chromium from contaminated aqueous solutions by using Moringa oleifera Lam. seeds. Parameters such as solution pH, adsorbent mass, contact time between solution and adsorbent, isotherms, thermodynamic, kinetics, and desorption were evaluated. The maximum adsorption capacity (Q m ) calculated to be 3.191 mg g −1 for the biosorbent. Activated carbon was used for comparison purposes in addition to the biosorbent. The best fit was obtained by the Langmuir model for both adsorbents. The average desorption value indicated that both the biosorbent and activated carbon have a strong interaction with the metal. The results showed that the biosorbent has advantages owing to its low cost and efficiency in Cr 3+ removal from contaminated waters.

The effectiveness of Crambe abyssinica Hochst seeds by-product as a biosorbent for the removal of cadmium ions from wastewater was analyzed. The biomass of crambe was characterized by scanning electron microscopy, infrared spectroscopy and determining the point of zero charge. The optimum adsorption conditions obtained were 400 mg of biomass in a solution of pH 6.0 and contact time of 60 min to remove 19.342 mg g(-1) cadmium ions. The isotherms of adsorption were constructed and, according to the mathematical linearization, the best fitting followed the Freundlich and Dubinin-Radushkevich models, describing a multilayer adsorption and chemical interaction, also confirmed by the pseudo-second order model and enthalpy value. In the desorption process, about 79% of cadmium ions that had been adsorbed were recovered. The same conditions applied for studying the isotherms of adsorption and desorption were used for comparative study with activated carbon. It was concluded that the use of crambe by-product as biosorbent for cadmium removal in wastewaters was not only a viable alternative to activated carbon, but also required no previous treatment, so it represents a sustainable material with high applicability and low environmental impact.

ResumoJatropha curcas Linn. conhecido como pinhão manso apresenta teor de óleo entre 35 e 38% em suas sementes, sendo utilizado como alternativa na produção de biodiesel. Porém, essa cultura apresenta frutificação desuniforme, o que desfavorece a determinação do período ideal de colheita. Desta forma, esse trabalho objetivou relacionar a coloração das sementes de Jatropha curcas Linn. durante o processo de maturação dos frutos com as características germinativas e concentração de óleo, verificando assim a melhor época para a colheita. Utilizando a carta de cores de Munsell, as sementes foram classificadas em 4 estádios: VC (sementes claras de frutos verdes), VE (sementes escuras de frutos verdes), A (sementes de frutos maduros presos à árvore) e C (sementes ao chão). Foi realizado o teste de germinação, umidade, matéria seca e teor de óleo das sementes. As sementes dos frutos secos presos à árvore (estádio A) resultaram em maior germinação, cerca de 25%, pois possuíam maior massa seca (90.51%) e menor teor de água (9.49%). No estádio A as sementes apresentaram também a maior concentração de óleo, que foi de 47.36% (amêndoa), sendo, portanto, o estádio mais indicado para a colheita dos frutos. As sementes claras de frutos verdes (VC), não apresentaram germinação satisfatória (1.25%). A cor do fruto é um parâmetro para indicação de maturidade fisiológica de sementes de Jatropha curcas Linn. Palavras-chave: Colorimetria, germinação, pinhão manso, maturidade fisiológica Abstract Jatropha curcas Linn., known as physic nut, is a plant that has oil content between 35 and 38%, being used as an alternative for producing biodiesel. However, this culture has uneven fruiting, which discourages the harvest period. This study aimed to relate the color of the seeds during fruit maturation and germination characteristics with the oil concentration, confirming the best time for harvest. Using the Munsell color chart the seeds were classified into four stages: VC (light seeds of unripe fruits), VE (dark seeds of unripe fruits), A (seeds of fruits attached to the tree) and C (seeds to the ground). It was conducted the germination test, moisture, dry matter and oil content. The seeds of fruits that were attached to the tree (level A) obtained better results in test of germination, about 25% because they had higher dry matter (90.51%) and lower water content (9.49%). They also had the largest concentration of

This study evaluated the efficacy of moringa seeds (Moringa oleifera Lam.) as an adsorbent material for removing toxic heavy metals such as cadmium, lead, and chromium from contaminated solutions. The effect of the adsorbent mass was investigated at two pH conditions (5.0 and 7.0). The optimized conditions were 0.300 g of adsorbent at pH 5.0, used for the isotherms construction, and linearized according to Langmuir and Freundlich models. Results showed that cadmium adsorption was similar in both the models used. For lead, the Freundlich model had the best adjustment and chromium was better adjusted by the Langmuir model. It was concluded that the adsorbent was effective in the remediation of solutions containing cadmium, lead and chromium, thus, its use as sustainable alternative material is feasible, since it has low cost, does not need a previous treatment and it is a byproduct. Key words: adsorption, isotherms, remediationAplicabilidade da torta de Moringa oleifera Lam. como adsorvente para remoção de metais pesados de águas RESUMO Este estudo objetivou avaliar a eficácia do uso da torta de moringa (Moringa oleifera Lam.) como material adsorvente dos metais pesados tóxicos cádmio (Cd), chumbo (Pb) e cromo (Cr) de soluções contaminadas. Nos testes cinéticos foram variadas as massas do adsorvente em duas condições de pH (5,0 e 7,0). As condições otimizadas foram pH 5,0 e massa de 0.300 g de adsorvente, utilizados para a construção das isotermas e linearizadas conforme os modelos de Langmuir e Freundlich. Realizou-se a determinação dos metais por espectrometria de absorção atômica. Os resultados mostraram que houve semelhança em ambos os modelos utilizados para a adsorção do Cd. Para o Pb, o modelo de Freundlich apresentou o melhor ajuste e, para o Cr, houve melhor ajuste pelo modelo de Langmuir. Conclui-se, com base nos resultados obtidos, que o adsorvente foi eficaz na remediação de soluções contendo Cd, Pb e Cr e, assim, é viável a utilização desse adsorvente como material alternativo sustentável, pois apresenta baixo custo, não necessita de tratamento prévio e se trata de um coproduto.