Search results for "Renewable Energy"
showing 10 items of 2318 documents
Start-up and Operation of Laboratory-Scale Thermophilic Upflow Anaerobic Sludge Blanket Reactors Treating Vegetable Processing Wastewaters
1997
Thermophilic anaerobic treatment of hot vegetable processing wastewaters was studied in laboratory-scale UASB reactors at 55°C. The high-strength wastewater streams, deriving from steam peeling and blanching of carrot, potato and swede were used. The reactors were inoculated with mesophilic granular sludge. Stable thermophilic methanogenesis with about 60% COD removal was reached within 28 days. During the 134 day study period the loading rate was increased up to 24 kg COD m−3 day−1. High treatment efficiency of more than 90% COD removal and concomitant methane production of 7·3 m3 CH4 m−3 day−1 were achieved. The anaerobic process performance was not affected by the changes in the wastewat…
Experimental alteration of granitic rocks: Implications for the evolution of geothermal brines in the Upper Rhine Graben, Germany
2020
Abstract Geothermal energy exploitation in the Upper Rhine Graben (URG) chiefly has targeted faults and fractures within or connected with the crystalline basement, where hot fluids of c. 200 °C circulate at depths of c. 5 km. Formation fluids of the crystalline basement are highly saline, NaCl-dominated brines, whereas shallow crystalline basement water ( The trace element concentrations of the leachates are hereby related to the composition and stability of minerals in the rocks and can be directly linked to the proposed and observed dissolution processes at the different temperatures. In experiments with pure water at 70 °C, representing the recharge or infiltration conditions, water-roc…
Application of a Novel Refinement Method for Accurate Determination of Chemical Diffusion Coefficients in Electroactive Materials by Potential Step T…
2005
We describe application of a novel refinement method for an accurate determination of the chemical diffusion coefficient, D, and the generalized kinetic parameter, A, from experimental potentiostatic intermittent titration technique (PITT) data suited for a variety of electrochemically doped electroactive polymers and inorganic intercalation host materials. The proposed, simple, two-step refinement procedure, based on earlier derived analytical expressions for the PITT response, is exemplified by the analysis of chronoamperometric responses to small-amplitude potential perturbation for p- and n-doped poly(fluorenone-bithiophene) (PFDOBT-HH) thin film electrode. The initial p-doping and the …
Reduced grey brookite for noble metal free photocatalytic H2evolution
2021
Herein we introduce for the first time a reduced “grey” brookite TiO2 photocatalyst, produced by thermal hydrogenation of brookite nanoparticles, that shows a remarkable noble metal free photocatalytic H2 evolution. Its activity is substantially higher than that of other TiO2 polymorphs, i.e. anatase or rutile, comparably sized and activated by hydrogenation under optimized conditions. Along with brookite powders, an oriented brookite single crystal was investigated as a defined surface to confirm the effects of the hydrogenation treatment. By a combination of electron paramagnetic resonance (EPR), electron and X-ray characterization techniques applied to the powders and single crystal, we …
Stabilizing nanostructured lithium insertion materials via organic hybridization: A step forward towards high-power batteries
2014
Abstract Herein, we present the electrochemical characterization of carbon-coated TiO 2 nanorods, obtained by carbonizing RAFT (reversible addition fragmentation chain transfer) polymerization derived block copolymers anchored on anatase TiO 2 nanorods. These carbon-coated TiO 2 nanorods show an improved electrochemical performance in terms of first cycle reversibility, specific capacity, cycling stability, and high rate capability. More importantly, however, the structural disordering observed in the uncoated TiO 2 nanorods by means of galvanostatic and potentiodynamic cycling as well as ex situ XRD analysis, does not occur for the carbon-coated material. Preventing this structural disorde…
Photoelectrochemical characterization of anatase-rutile mixed TiO2 nanosponges
2016
This work studies the influence of using hydrodynamic conditions during anodization on the morphology and electrochemical properties of anatase/rutile mixed TiO2 nanotubes (Reynolds number, Re = 0) and nanosponges (Re > 0). To this purpose different techniques were used, such as: microscopy techniques (Field-Emission Scanning Electron Microscope, FE-SEM, and Confocal Laser-Raman Spectroscopy), Electrochemical Impedance Spectroscopy (EIS), Mott Schottky (MS) analysis and photoelectrochemical water splitting tests. This investigation demonstrates that the morphology of TiO2 nanostructures may be greatly affected due to the hydrodynamic conditions and it can be adjusted in order to increase th…
Photocatalytic Selective Oxidation of 5-(Hydroxymethyl)-2-furaldehyde to 2,5-Furandicarbaldehyde in Water by Using Anatase, Rutile, and Brookite TiO2…
2013
5-(Hydroxymethyl)-2-furaldehyde (HMF) was selectively oxidized to 2,5-furandicarbaldehyde (FDC) in; aqueous medium by using home prepared (HP) anatase, rutile, and brookite TiO2 nanoparticles. HP samples were prepared via a sol-gel method by using TiCl4 as the TiO2 precursor. Commercial TiO2 catalysts were also used for, comparison. All samples were characterized by BET specific surface area, XRD, TGA, and SEM, and the reactivity results showed that HP catalysts are predominantly amorphous and give rise to selectivities toward FDC more than twice that of commercial and well crystallized catalysts.
Generalized power-angle control for grid-forming converters: A structural analysis
2022
Several control schemes have been recently proposed and studied as grid-forming controls for power converters. In all these schemes, the power-angle control loop is the part which defines the fundamental capabilities of the grid-forming control: that control loop governs in fact the inherent synchronization mechanism of the power converter, the power sharing with the other generation sources in the system and the oscillatory characteristics of the converter-based resource. This article introduces a general formulation for the power-angle control characterizing the grid-forming concept for power converters. The generalized power-angle control is based on a polynomial fraction formulation, an…
Gas assisted mechanical expression (GAME) for the selective recovery of lipophilic and hydrophilic compounds from olive kernel
2017
Abstract This work is devoted to valorize olive kernel; a by-product produced during olive oil extraction process. For this purpose, aqueous liquid solid extraction (LSE), mechanical expression (ME), supercritical CO2 (SC-CO2) and gas assisted mechanical expression (GAME), processes were compared when applied separately or consequently (ME + GAME), in terms of total phenolic compound (TPC) and oil recovery yields. Results showed that although the high extraction yields of TPC using LSE (61.4 ± 1.3%), the extraction process is economically not viable. However, it was demonstrated that applying ME (1 h at 30 MPa) followed by GAME (1 h at 30 MPa ME and 10 MPa SC-CO2 pressures) allowed recoveri…
ZnO nanorods covered with a TiO2 layer: simple sol–gel preparation, and optical, photocatalytic and photoelectrochemical properties
2015
In this work, composite core–shell ZnO/TiO2 materials were fabricated by deposition of TiO2 layers via a sol–gel method onto ZnO nanorods hydrothermally grown on an ITO electrode. Two approaches to the sol–gel procedure resulted in strongly different morphologies and thicknesses of the deposited TiO2 layer, as shown in electron microscopy studies. The decrease of the optical band gap energies of the ZnO/TiO2 composites by about 0.2–0.3 eV with respect to the TiO2 nanoparticles and ZnO nanorods was determined from UV-Vis diffuse reflectance spectra. The photocatalytic activities of the systems were determined by investigation of the decolorization of Methylene Blue (MB) in aqueous solution, …