Electrochemical detection of lead at zinc oxide nanostructure based modified electrode

A modified glassy carbon electrode (ZnO-Nafion/GCE) prepared by drop-casting technique, was investigated by square wave anodic stripping voltammetry (SWASV) for the detection of Pb2+ in synthetic and reals water samples

Preparation, Characterization and Gas Permeation Investigation of Resorcinol-Formaldehyde Polymer or Carbon Xerogels/Tubular Ceramic Composites

New very stable composites prepared by deposition of resorcinol-formaldehyde polymer (RF-) or carbon (C-) xerogels into walls of commercial porous tubular ceramics (TiO2-ZrO2 and αAl2O3-γAl2O3) were obtained by a sol-gel process followed by a drying and a pyrolytic (only for C-xerogel/ceramic composites) step. They were characterized by nitrogen adsorption-desorption, SEM and XRD, and tested for gas (H2, CH4, CO2 and CO) separation applications. Additional morpho-structural information about the open-interconnected ultramicropore structure of composites was found by gas permeation investigation. Interesting results for H2 permeance was obtained especially for RF-polymer/ceramic composites respecting Knudsen diffusion mechanism of gas permeance: H2 > CH4 > CO > CO2. The coexistence of Knudsen and surface diffusion mechanisms were confirmed.Postprint (published version

Influence of HAP on the Morpho-Structural Properties and Corrosion Resistance of ZrO₂-Based Composites for Biomedical Applications

In the present work, ZrO2-based composites were prepared by adding different amounts of antibacterial magnesium oxide and bioactive and biocompatible hydroxyapatite (HAP) to the inert zirconia. The composites were synthesized by the conventional ceramic processing route and morpho-structurally analyzed by X-ray powder diffraction (XRPD) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Two metallic dental alloys (i.e., Ni–Cr and Co–Cr) coated with a chitosan (Chit) membrane containing the prepared composites were exposed to aerated artificial saliva solutions of different pHs (i.e., 4.3, 5, 6) and the corrosion resistances were investigated by electrochemical impedance spectroscopy technique. The obtained results using the two investigated metallic dental alloys shown quasi-similar anticorrosive properties, having quasi-similar charge transfer resistance, when coated with different ZrO2-based composites. This behavior could be explained by the synergetic effect between the diffusion process through the Chit-composite layer and the roughness of the metallic electrode surface

Preparation, Characterization and Gas Permeation Investigation of Resorcinol-Formaldehyde Polymer or Carbon Xerogels/Tubular Ceramic Composites

New very stable composites prepared by deposition of resorcinol-formaldehyde polymer (RF-) or carbon (C-) xerogels into walls of commercial porous tubular ceramics (TiO2-ZrO2 and αAl2O3-γAl2O3) were obtained by a sol-gel process followed by a drying and a pyrolytic (only for C-xerogel/ceramic composites) step. They were characterized by nitrogen adsorption-desorption, SEM and XRD, and tested for gas (H2, CH4, CO2 and CO) separation applications. Additional morpho-structural information about the open-interconnected ultramicropore structure of composites was found by gas permeation investigation. Interesting results for H2 permeance was obtained especially for RF-polymer/ceramic composites respecting Knudsen diffusion mechanism of gas permeance: H2 > CH4 > CO > CO2. The coexistence of Knudsen and surface diffusion mechanisms were confirmed

Carbon Aerogel as Electrode Material for Improved Direct Electron Transfer in Biosensors Incorporating Cellobiose Dehydrogenase

High mesoporous carbon aerogels (CA) were prepared by a sol-gel method, followed by supercritical drying with liquid CO2 and pyrolysis under inert atmosphere. The morphological and structural characteristics (surface area, pore size distribution and pore volume) of CA were examined by using N2 adsorption/desorption isotherms, TEM, SEM and AFM measurements. CA, dispersed in a chitosan (Chi) solution, was immobilized on the surface of a glassy carbon (GC) electrode aiming to prepare an amperometric transducer able to improve the direct electron transfer (DET) between Phanerochaete chrysosporium cellobiose dehydrogenase (PcCDH) and the electrode. The resulting GC/CA-Chi/PcCDH biosensor was optimized with regards to the loading of CA and PcCDH, as well as pH of the buffer solution. The electroanalytical parameters of the optimized biosensor (maximum current responses (Imax), apparent Michaelis-Menten constants (KM)) were estimated from amperometric calibration curves for lactose. The remarkably high sensitivity towards lactose (133.7±0.2 µA cm−2 mM−1) at the GC/CA-Chi/PcCDH electrode recommends the GC/CA-Chi electrode as an efficient transducer for PcCDH based biosensors, exploiting DET

Preparation, Characterization and Gas Permeation Investigation of Resorcinol-Formaldehyde Polymer or Carbon Xerogels/Tubular Ceramic Composites

New very stable composites prepared by deposition of resorcinol-formaldehyde polymer (RF-) or carbon (C-) xerogels into walls of commercial porous tubular ceramics (TiO2-ZrO2 and αAl2O3-γAl2O3) were obtained by a sol-gel process followed by a drying and a pyrolytic (only for C-xerogel/ceramic composites) step. They were characterized by nitrogen adsorption-desorption, SEM and XRD, and tested for gas (H2, CH4, CO2 and CO) separation applications. Additional morpho-structural information about the open-interconnected ultramicropore structure of composites was found by gas permeation investigation. Interesting results for H2 permeance was obtained especially for RF-polymer/ceramic composites respecting Knudsen diffusion mechanism of gas permeance: H2 > CH4 > CO > CO2. The coexistence of Knudsen and surface diffusion mechanisms were confirmed