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.
The design and development of efficient and electrocatalytic
sensitive
nickel oxide nanomaterials have attracted attention as they are considered
cost-effective, stable, and abundant electrocatalytic sensors. However,
although innumerable electrocatalysts have been reported, their large-scale
production with the same activity and sensitivity remains challenging.
In this study, we report a simple protocol for the gram-scale synthesis
of uniform NiO nanoflowers (approximately 1.75 g) via a hydrothermal
method for highly selective and sensitive electrocatalytic detection
of hydrazine. The resultant material was characterized by scanning
electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction.
For the production of the modified electrode, NiO nanoflowers were
dispersed in Nafion and drop-cast onto the surface of a glassy carbon
electrode (NiO NF/GCE). By cyclic voltammetry, it was possible to
observe the excellent performance of the modified electrode toward
hydrazine oxidation in alkaline media, providing an oxidation overpotential
of only +0.08 V vs Ag/AgCl. In these conditions, the peak current
response increased linearly with hydrazine concentration ranging from
0.99 to 98.13 μmol L–1. The electrocatalytic
sensor showed a high sensitivity value of 0.10866 μA L μmol–1. The limits of detection and quantification were
0.026 and 0.0898 μmol L–1, respectively. Considering
these results, NiO nanoflowers can be regarded as promising surfaces
for the electrochemical determination of hydrazine, providing interesting
features to explore in the electrocatalytic sensor field.
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