ObstractThe release of industrial effluents into the environment causes widespread contamination of aquatic systems. Adsorption is seen as one of the most promising treatment processes, and lignocellulosic materials have gained prominence as adsorbents. This study investigates the potential of rice hulls, either in natura or treated with nitric acid, as adsorbents for removal of the dye. The adsorbents were characterized by infrared spectroscopy, solid state 13 C-NMR, thermogravimetric analysis, and pH at point of zero charge. The dye adsorption experiments were carried out in batch mode, using different experimental conditions. The kinetic adsorption data could be fitted using the model of Elovich. The Freundlich model provided the best fit to the isothermal data. The thermodynamic parameters confirmed the spontaneity of the adsorption process. These adsorbents offer an alternative for dye removal, with advantages including biomass availability and low cost.

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A bioactive compound was quantified on a bare glassy carbon electrode by BIA-MPA. This method is simple, fast, and cost effective.

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Brazil has the greatest plant diversity on the planet, distributed in different types of biomes. These plants are important sources of biologically active natural products, which are derived from various drugs marketed worldwide. This paper presents an electrochemical study of three unusual dimeric flavonoids, pharmacologically active, isolated and identified for the first time by our research group, in a Brazilian plant (Fridericia platyphylla). The results showed that oxidation processes are favored at higher pH, and mass transport was controlled by diffusion. Brachydins derivatives, Bra-A was oxidized at the lowest potential value (0.48 V vs. Ag/AgCl, KCl(sat)) and Bra-B and Bra-C, presented the highest oxidation potentials (ca. 0.71 and ca. 0.57 V vs. Ag/AgCl, KCl(sat), respectively). This study shows that electrochemistry is one more tool that would help us focus on future bio-pharmacological investigations of these unusual compounds.