No abstract

In this work, the potential removal of Cd, Cu, and Zn ions by non-living macrophytes Egeria densa has been studied. The adsorption kinetic and equilibrium experiments of these three metals on E. densa were performed in batch systems with controlled temperature and constant shaking. It was observed that all metal adsorption rates have increased when the pH was increasing. A pH threshold of 5 was established for use in adsorption experiments in order to avoid the metal precipitation. For adsorption kinetic tests, the equilibrium times for all metals were around 45 to 60 min. The equilibrium data at pH 5 were better described by the Langmuir isotherm than the Freundlich one, with the adsorption rate and maximum metal content values of 0.43 L g −1 and 1.25 mequiv g −1 for Cd, 4.11 L g -−1 and 1.43 mequiv g −1 for Cu, and 0.83 L g −1 and 0.93 mequiv g −1 for Zn. These adsorption parameters for E. densa resemble or are better than those for other biosorbents already studied, suggesting that the macrophytes E. densa as a biosorbent has a good metal removal potential for applications in effluent treatment systems.

No abstract

This research evaluated the biosorption potential of the 134% Yellow Reafix BR2 dye by the malt bagasse. Tests were conducted at batch conditions, under controlled agitation, pH, and temperature. The biosorbent was characterized through scanning electron microscopy and Fourier transform infrared spectroscopy, before and after biosorption. Malt bagasse presented a point of zero charge at 6.75. In the process variables evaluation, there was a greater biosorption potential in acidic pH, without a significant influence of size on the biosorbent particles. The equilibrium time was achieved in 360 min, with approximately 93% removal at the evaluated temperatures. The experimental data were best represented by the pseudo-second-order model. Biosorption was characterized as spontaneous and endothermic, with indicative of physical. Considering the equilibrium, the Langmuir isotherm was the one that best fit the experimental data, with a maximum biosorption capacity of 68.75 mg g-1 (at 303 K and pH 2). The removal suffered no significant interference with the presence of another dye nor with the increase of ionic strength. Thus, the malt bagasse shows potential to be used as a biosorbent in treatment systems of industrial effluents.

Neste trabalho, foi estudada a capacidade de biossorção da macrófita aquática Egeria densa seca na remoção do íon zinco. Os testes cinético e de equilíbrio foram realizados em sistema de batelada com temperatura, agitação e pH controlados. Os resultados obtidos na cinética de biossorção demonstram uma rápida remoção do zinco (II), com tempo de equilíbrio em torno de 45 minutos e taxa de remoção superior a 70%. O modelo cinético de pseudo-segunda ordem foi o que melhor representou os dados experimentais. No estudo do equilíbrio, verificou-se que o modelo de Langmuir ajustou-se melhor aos dados experimentais, com capacidade máxima de sorção de 0,92 mequiv g-1 e razão entre as taxas de sorção e dessorção de 0,829 L g-1 em pH 5. Os resultados obtidos demonstram que a macrófita E. densa tem potencial para ser utilizada em sistemas de tratamento de efluentes industriais.