1,721,654 research outputs found
Assessing the Performance of Continuous-Flow Microbial Fuel Cells and Membrane Electrode Assembly with Electrodeposited Mn Oxide Catalyst
Get PDFMicrobial fuel cells (MFCs) are considered promising energy sources whereby chemical energy is converted into electricity via bioelectrochemical reactions utilizing microorganisms. Several factors affect MFC performance, including cathodic reduction of oxygen, electrode materials, cell internal and external resistances, and cell design. This work describes the effect of the catalyst coating in the air-cathode membrane electrode assembly (MEA) for a microbial fuel cell (MFC) prepared via electrodeposition of manganese oxide. The characterization of the synthesized air-cathode MFC, operating in a continuous mode, was made via electrochemical impedance spectroscopy (EIS) analyses for the determination of the intrinsic properties of the electrode that are crucial for scalability purposes. EIS analysis of the MFCs and of the MEA reveals that the anode and cathode contribute to polarization resistance by about 85% and 15%, respectively, confirming the high catalytic activity of the Mn-based air cathode. The maximum power density of the Mn-based cathode is about 20% higher than that recorded using a Pt/C electrode
Bibliometric analysis on the papers dedicated to microplastics in wastewater treatments
Get PDFThe presence of microplastics (MPs) in the environment is becoming a problem for soils and seas, as well as for the food chain of animals and humans. The scientific community has been called upon to contribute to solving the problem and several papers have been published, especially in the last decade. The aim of this work is to carry out a bibliometric analysis of the scientific literature dedicated to the problem of MPs, highlighting its course over the years, and to identify the sectors to which the research could be profitably addressed. The VOSviewer software has been used to perform the analysis of the data in which specific maps were used to represent the network of the relationships among countries, journals, organizations, authors, and keywords related to the investigated topic and subtopics. The results of the survey demonstrated that during the investigated range of time, most attention has been paid to the individuation of the MPs, and to marine pollution, while a gap seems to exist in the possible advanced oxidation processes specifically addressing the degradation of MPs and their derivates
Photoelectrocatalytic degradation of harmful compounds
No full textAbstract Photoelectrocatalytic (PEC) processes are among the hybrid or combined processes that are receiving great attention in this latter period. Thanks to the possible exploitation of renewable energies, the use of electricity is no longer the weakest point of the electrochemical processes, and therefore their exploitation is regaining the deserved attention. The combination of electrocatalytic (EC) and photocatalytic (PC) processes, which occurs in the PEC processes, can be considered as a useful means that in perspective will be able to use the synergies of the two processes in an economically and environmentally sustainable way: all research is in fact aimed at the realization of systems that exploit solar energy in the so-called Solar PEC Processes
Computational modelling as a design tool for bioelectrochemical systems
Get PDFDesign of bioelectrochemical systems (BESs) needs to consider complex biological, physicochemical, and electrochemical phenomena, as well as aspects related to mass, charge and momentum transfer. Experimental optimisation of such complex systems will be too expensive in terms of time and cost, so that a model-based approach is a necessary route in BES design. In this work, the relevance of modelling in the literature on BESs is quantitatively assessed, and the main pros and cons of the different models of BES are identified. Among the different models, computational bioelectrochemical models (CBMs) are the most promising, the main potential and drawbacks of CBMs are then discussed, and the issues open for future research are indicated
Modelling of photo-electrocatalytic behaviour of TiO2 nanotubes under solar light irradiation
Get PDFA mathematical model of the photo-electrochemical processes occurring during irradiation with solar light has been implemented, to evaluate the optimal geometry of TiO2 nanotubular structures for the different applications. The model accounts for generation and recombination of charge carriers, as well as for transport phenomena in solid phase. Electrochemical reactions at the surface and chemical processes in liquid phase are also modelled. The solar irradiation has been discretised in the UV and visible range, and adsorption coefficients as a function of the wavelength have been used. The model has been solved for oxidation of water, as well as for oxidation of organic compounds with different reactivity. The effect of such variables as light intensity, electric potential and reactivity of the organic compounds on space distribution of charge carriers in solid phase, oxygenated radicals and organic compounds in liquid phase, have been determined. The model provides a versatile tool to assess the performances of nanotubular electrodes at microscale and makes possible the optimal design of the nanostructure
Effect of potential and chlorides on photoelectrochemical removal of diethyl phthalate from water
Get PDFRemoval of persistent pollutants from water by photoelectrocatalysis has emerged as a promising powerful process. Applied potential plays a key role in the photocatalytic activity of the semi-conductor as well as the possible presence of chloride ions in the solution. This work aims to investigate these effects on the photoelectrocatalytic oxidation of diethyl phthalate (DEP) by using TiO2 nanotubular anodes under solar light irradiation. PEC tests were performed at constant potentials under different concentration of NaCl. The process is able to remove DEP following a pseudo-first order kinetics: values of kapp of 1.25 × 10−3 min−1 and 1.56 × 10−4 min−1 have been obtained at applied potentials of 1.8 and 0.2 V, respectively. Results showed that, depending on the applied potential, the presence of chloride ions in the solution affects the degradation rate resulting in a negative effect: the presence of 500 mM of Cl− reduces the value of kapp by 50 and 80% at 0.2 and 1.8 V respectively
Photoelectrochemical oxidation of phenol with nanostructured TiO2-PANI electrodes under solar light irradiation
No full textThe photoelectrochemical removal of phenol from aqueous solution under solar light with polyaniline-modified TiO2electrodes has been investigated. Nanotubular TiO2electrodes (NTs) have been obtained by anodization of Ti; the coating with polyaniline (PANI) has been obtained with a three-step approach: (i) functionalization of NTs by electroreduction of 4-nitrobenzendiazonium salt, (ii) electrochemical reduction of the nitro group to amine, (iii) galvanostatic electropolymerisation of aniline. The results of galvanostatic electrolyses under simulated solar light are presented, degradation of phenol with TiO2was achieved and the trends of concentration with time follow a pseudo-first order kinetics. As a comparison, also unmodified NTs have been tested. The results depend on the initial concentration of reactant, with 300 mg dm−3of phenol and applying a current density i = 0.18 mA cm−2, the reaction rate with NT-PANI was more than double of that obtained with NTs. Moreover, the presence of PANI increases the conductivity of the electrode, which in turn depolarizes the cell. Hydroquinone and oxalic acid have been detected as main intermediates, which are distributed depending on the experimental conditions and kind of electrodes: the relevant data have been modelled assuming an in-series reaction scheme and pseudo first order kinetics
Assessing an electrochemical process for the treatment of tar-containing wastewater with hydrogen recovery
Get PDFBiomass gasification generates syngas with low carbon emissions but produces tar-contaminated wastewater that challenges environmental sustainability. This study explored using an alkaline electrolysis process with a DSA anode to remove organic pollutants from the effluent of a wet scrubber in a biomass gasification plant's syngas clean-up system. The effect of current density (16, 80, 160 mA cm−2), area-to-volume ratio (0.03 and 0.15 cm−1), and organic load on the process performances was assessed by monitoring total organic carbon, chemical oxygen demand and UV–Vis analyses; the phenolic fraction was also analysed with 4-aminoantipyrine colorimetric method. A kinetic analysis with zero-order and pseudo-first-order kinetic models was done for the relevant parameters, and the kinetic constants (kapp) were evaluated under all the explored conditions. Results showed lower organic loads (higher dilution), as well as increasing current densities, have a beneficial effect on the phenol removal and mineralisation, achieving up to 50 % mineralisation in 8 h with 1:100 wastewater at 160 mA cm−2 and 0.15 cm−1. Also, reducing the area-to-volume ratio leads to slower mineralisation processes. On the other hand, adopting low current densities with high organic loads lead to 100 % instantaneous current efficiency, in which the oxygen evolution reaction is fully suppressed, and pure hydrogen is produced. Insights into the economic aspects of the process in terms of energy per order and energy per mass were given: the energy consumption for the most favourable condition is 15.95 kWh kg−1, corresponding to 960 kWh m−3 and a total cost of 72 € m−3
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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