No abstract

The contamination of both soil and water by nitrobenzene (NB) is a problem that has been studied, where several reactive agents have been developed for the degradation of this compound as well as different methods. Nanoparticles with semiconductive properties have been studied for organic compounds photodegradation due to their assistance in optimizing the degradation processes. Two of the most promising photocatalysts are ZnO and TiO2 because of their optimal results. In the present work the performance of the zinc peroxide (ZnO2) nanoparticles was evaluated. ZnO2 nanoparticles were synthesized from zinc acetate and hydrogen peroxide using the Sol-Gel method under ultrasound assistance. The characterization was carried out by UV–Vis spectroscopy, infrared Fourier transform total reflectance (ATR-FT-IR) spectroscopy, Raman spectroscopy, X-ray diffraction (XRD), Zeta potential, dynamic light scattering (DLS), field emission scanning electron microscopy (FE-SEM), and Energy Dispersive X-ray spectroscopy (EDX). The experiments for the degradation of NB were carried out in a photoreactor with UV lamps of 254 nm at 25 °C, using a solution of nitrobenzene with the nanoparticles. The best conditions for NB photodegradation were 30 ppm (ZnO2) and 15 ppm (NB) at pH 2, reaching up to 90% degradation in 2 h. The intermediates formed during the photodegradation of NB were identified by gas chromatography mass spectrometry.

In this work, electrochemical generation of ferrate ion (FeO4-2) using a prototype of batch electrochemical reactor with agitation was studied. The anode used was a piece of steel tube (ASTM-A53) of 2 inches of nominal diameter and the cathode used was a steel bar of 0.5 inches. In the electrochemical reactor we did not use membranes, in order to diminish production costs and to make it a much more competitive and attractive process. Two different electrolytes were tested as reactant medium in the system: NaOH (10 M) and KOH (10 M). A current density of 53.62 mA/cm2 was applied with respect to the anode during a period of time of two hours. Afterwards the concentration of ferrate was determined in function of time using a spectroscopy method. It was found that the concentration of ferrate is higher in NaOH as reactant medium than KOH.

In this work, a sensitive and highly stable non-enzymatic glucose sensor is reported. It is based on self-assembled 3-mercaptophenylboronic acid (3MPBA) self-assembled on small Pt nanoparticles supported on a multi-wall carbon nanotubes (CNTs) surface. The materials characterization was performed by thermal analysis (TGA), scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), cyclic voltammetry (CV), and Z potential measurements. Glucose and fructose evaluation was carried out by hydrodynamic zeta potential measurements using the streaming potential, presenting high selectivity to glucose in the alkaline medium. The 3MPBA-PtNPs-CNTs electrode exhibit a linear response in the glucose concentration range of 0 to 10 mM, high sensitivity to 22.25 mV mM−1, and ultra-low detection of 4.5 μM.