In this study, the removal of zinc (Zn 2+ ) from aqueous solutions was investigated using a Na-enriched Brazilian gray clay. The mineral clays were characterized through EDX, XRD analysis and CEC. A finite bath system was used to evaluate the main effects of mechanical agitation (from 100 to 200 rpm), pH values in the range from 6.0 to 8.0 and Zn 2+ initial concentrations (from 10 to 50 mg/L) on the removal process capacity. Langmuir and Freundlich isotherm models were applied in order to determine the efficiency of clay used as an adsorbent. According to the obtained results, Langmuir model adjusts very well to the experimental data. Based on the kinetic studies for the Na-enriched gray clay, it was verified that the mechanism corresponds to a predominant pseudo-second order adsorption, presenting a kinetic constant value equal to k = 1.13 (g·min/mg).
Heavy industrial activities result in contamination of waste water with many heavy metals, including cadmium, nickel, lead, mercury. Within this context becomes a growing concern of the population and environmental agencies regarding water contamination by heavy metals from industrial effluents. Because of this problem, this paper aims to study and evaluate the main properties of natural Brasgel clay in order to remove cadmium from synthetic effluents, analyzing its kinetic adsorption and its isothermal balance. Once clays exhibit good cation exchange capacity, selectivity and regenerability and for this reason has aroused interest in the use as an adsorbent. As finite bath testing we found that the Brasgel clay, removed approximately 90% of cadmium. The Langmuir model presented best fit to the experimental data, adequately describing the dynamics of adsorption. Kinetic tests indicated that the cadmium removal process by natural Brasgel clay apply the mechanism of the pseudo-second-order rate model, a time of 20 minutes and required to reach equilibrium. Thus, the results indicated that Brasgel clay can be used as an adsorbent for the removal of cadmium from contaminated effluent.
O trabalho teve como objetivo produzir catalisadores heterogêneos a base de argila verde dura natural (VD) e impregnação do óxido de molibidênio. Estes catalisadores foram avaliados na reação de transesterificação do óleo de soja com metanol para produzir biodiesel. Foram avaliados os efeitos do tempo de reação (1, 2, 3, 4, 5 e 6 h) e catalisador (VD e MoO3/VD) sobre a viscosidade cinemática do biodiesel. Os catalisadores (VD e MoO3/VD) foram caracterizados por DRX, FRX-ED, Adsorção física de N2, MEV, IV e TPD. A reação de transesterificação do óleo de soja foi conduzida em reator batelada sem agitação, durante tempos diferentes de reação (1, 2, 3, 4 e 6 horas) a 200 °C, utilizando uma relação óleo de soja/metanol de 1:12 e 5 % de catalisador. O produto obtido foi caracterizado a partir da viscosidade cinemática. Foi observado com o catalisador VD que os valores estão muito distantes aos padrões estabelecidos pela Agência Nacional de Petróleo, Gás Natural e Biocombustíveis (ANP), n° 4 de 2012. Enquanto que os valores de viscosidade com o catalisador MoO3/VD com os tempos de 5 e 6 horas de reação se aproximaram aos padrões estabelecidos pela ANP. Nesse sentido, a inserção do molibdênio na argila verde dura natural proporcionou um efeito positivo ao catalisador.
CABRERA, W. A Ludicidade para o ensino médio na disciplina de biologia. Contribuições ao processo de aprendizagem em conformidade com os pressupostos teóricos da Aprendizagem Significativa.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.