The objective of this study was to evaluate the effect of treatment with simple or coated nanoparticle and concentrations on storage time and the germination parameters in corn seeds. The treatments composed of three magnesium sources, magnesium oxide nanoparticles and nanoparticles in the form of (MgO NPs), magnesium carbon oxide core-shell nanoparticles (MgO@C NPs) and magnesium nitrate [Mg(NO3)2]. Six concentrations 0 (control) 37.5, 75, 150, 300 and 600 mg.L-1 were applied. The treated seeds were submitted to germination tests, after different storage times: 0, 30, 60, 90 and 150 days and then the normal and abnormal seedlings were evaluated. The results indicate that the treatment process with simple or coated nanoparticles with optimal concentration value, between 75 and 150 mg.L-1 of Mg, can approximately increase 6% of normal seedlings in conjunction with the storage time (90-150 days). The exposure of the seeds to magnesium nitrate resulted in less normal plants, possibly due to the saline and toxic effect of this source. The best germination performance of seeds pretreated with simple or coated nanoparticles can be achieved at the concentration of 75 mg.L-1 and for the storage time of 150 days. There might be some negative effect for magnesium nitrate depending on concentration and storage time.
Zinc is an important chemical element in many metabolic mechanisms at low concentrations, but can be toxic when administrated in doses higher than 500 µg•g-1 or 3 mg•L-1. This metal has been detected in many aquatic environments due to several industry activities and swine manure effluents. Thus, the contaminant removal of water and wastewater has been a major challenge. Many processes are applied and evaluated in an attempt to removal zinc found in environment, such as adsorption. In the present study Fe 3 O 4 @C core-shell nanoparticles were synthesized and used to adsorb ionic zinc species in aqueous solutions. The core-shell nanoparticles exhibited excellent zinc removal capacity, with a maximum efficiency equal 65% where applied in an aqueous solution containing 10 mg•l-1 of this ionic metal.
Semiconductors have been evaluated to heterogeneous photocatalysis degradation of recalcitrant contaminants in aqueous media due to the capacity of mineralizing these compounds under UV or visible light irradiation. However, this process has the inherent feature of photogenerated charges recombination and the high bandgap energy of the electronic structure of some semiconductors that can reduce the formation of reactive oxygen species, which are responsible for the compound degradation. In this context, structural modifications in semiconductors have been proposed to enhance the photocatalytic activity, such as doping processes with elements that are capable of generating superficial defects that capture the formed electrons, avoiding the recombination, or increasing the density of-OH groups or water molecules on the surface of the catalyst, which can enhance the formation of hydroxyl radicals. Therefore, this brief review is proposed to show the role of lanthanides in the TiO 2 doping and the synthesis method applied, as well as the results discussed in the literature.
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