FORMATION OF HIERARCHICAL CUO NANOWIRES ON A COPPER SURFACE VIA A ROOM-TEMPERATURE SOLUTION-IMMERSION PROCESS

CuO nanowires were successfully made through a simple wet chemical method at room temperature by immersing on copper sheets in a 4 M ammonia solution for 4 days and then subjecting it to heat treatment. Immersion time and heat treatment have an important effect on the length, diameter, and density of the CuO nanostructures. X-ray powder diffraction (XRD) patterns indicated that the samples are composed of a single phase, CuO. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy studies showed that the wet-treated samples consisted of nanofiber-like structures of monoclinic CuO, while the heat-treated samples consisted of well-defined nanowires which also exhibited the monoclinic phase.This work was supported by the DGIP of the Universidad Católica del Norte. We acknowledge a grant from Minera Escondida Limitada (MEL 22) and project ESO-AUI. R.A.Z. acknowledges grants from FUNDACIÓN ANDES under contract C-13876

Removal of arsenic and iron from acidic water using zeolite and limestone: batch and column studies

Zeolite and limestone were tested for their capability of removing As and Fe from acidic water in batch and column experiments. Synthetic acidic water with 3 mg/L As and 50 or 100 mg/L Fe at pH = 2 was used in the column experiments. In the batch experiments, the As concentration, the mass of media, and the contact time were varied between 0.2 and 5 mg As/L, 0.5 and 50 g, and 0.25 and 42 h, respectively. Maximum As sorption capacity as indicated by the Langmuir model was 0.17 mg/g for zeolite and 1.3 mg/g for limestone, at 18-h contact time and 6.3 g/L medium concentration. Energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy analyses revealed that As and Fe were retained in zeolite at the end of the batch experiments. The main factors affecting As and Fe removal efficiency and pH raising capacity were the contact time and the media concentration. This was confirmed in the column experiments, since zeolite and limestone columns presented 99% As removal, under a hydraulic loading rate of 21.8 mm/day. However, limestone columns presented a higher Fe removal: 99 versus 73% for zeolite. The results indicate that limestone could be more appropriate than zeolite when As and Fe are present under acidic conditions, given its higher capacity to remove both As and Fe and to raise pH.Department of Civil Engineering Concurso U-Inicia VID, Universidad de Chile CONICYT FONDECYT initiation into research grant 1115040

Mineral magnetite as precursor in the synthesis of multi-walled carbon nanotubes and their capabilities of hydrogen adsorption

Artículo de publicación ISIMineral magnetite was used as metallic oxide catalysts in the synthesis of Multi-Walled Carbon Nanotubes (MWCNTs) by Aerosol Assisted Chemical Vapor Deposition (AACVD). The structural and morphological information of MWCNTs was obtained by X-ray Diffraction (XRD), Raman Spectroscopy (RS), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). The hydrogen storage capacity and the gas adsorption kinetics of the MWCNTs exposed to H-2 at different pressures were determined using a quartz crystal microbalance (QCM). It was found that the hydrogen adsorption capacity was strongly dependent on the chemical, structural and morphological characteristics of the MWCNTs which, in turn, depend on the proportion of the starting materials (mineral magnetite and zeolite) used for the synthesis by AACVD. However, no a clear correlation was found between each one of these characteristics and the adsorption properties since the sample was affected by gas exposure during the H-2 loading/unloading cycles. The maximum adsorption capacity was 1.76 wt% at 44 Torr of H-2 exposure pressure. The adsorption kinetics was determined by in situ monitoring the QCM resonance frequency. As expected, a faster H-2 adsorption kinetics of the MWCNTs occurred when the sample was exposed to higher H-2 pressures. In general, there are measurable H-2 adsorption between 60 s and 100 s before reaching saturation.Government Research Agency (FONDECYT) of Chile 1150475 11130555 Government Research Agency (CONICYT) of Chile ACT1117 ID14I1012

Hydrothermal growth of zirconia nanobars on zirconium oxide

Zirconia nanorods and nanoparticles were grown hydrothermally starting from zirconium monoxide powder. The process was performed in an autoclave using NaOH as a mineralizer at nominal concentrations 15 M, 20 Mand 25 M, and at a temperature of 200 °C for 1 week. The samples were characterized by high resolution transmission electron microscopy, showing that the nanorod diameter spanned from 25 to 200 nm and their length from a few hundred nm up to 2 μm. X-ray photoelectron spectrometry showed that after the treatment all the material was zirconium (IV) oxide, as confirmed by X-ray diffraction and selected area electron diffraction. The latter showed that the nanobars were in the monoclinic phase and the nanopowders in the tetragonal one

Hydrogen adsorption properties of Ag decorated TiO2 nanomaterials

In this work, we present the synthesis of Ag doped TiO2 materials. The products are characterized by powder X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, nitrogen adsorption, and hydrogen adsorption. The Ag/TiO2 materials exhibit 3.65 times higher in hydrogen adsorption capability compared with the non-doped TiO2 materials thank to the existence of Ti3+ species, which are Kubas-type hydrogen adsorption centers, and the Ag nanoparticles which provide spillover effects. We believe that this is the first time that both Kubas-type adsorption and spillover are exploited in the design of novel hydrogen storage materials.CONICYT CONICYT/FONDAP/1511001

Study of phospholipid bilayers supported on chitosan-titanium nitride coatings produced by plasma immersion ion implantation (PIII)

FONDECYT 1170261 1141105 Postdoctoral Fellowship FONDECYT 3160803 3160179 FONDECYT INICIACION 11160664 CONICYT-PIA ACT 1108 140