关键词： Electrochemical impedance spectroscopy  

摘要： Electrochemical impedance spectroscopy (EIS) is an experimental technique that is frequently used in electrochemistry. While measuring EIS spectra is relatively simple, the interpretation of the data is hindered if the electrochemical system under study is not linear, causal, stable, and time-invariant. These requirements can be assessed by applying the Kramers-Kronig relations or Hilbert transform (HT) to the EIS data. Here, we develop a new probabilistic approach to compute the HT of impedance spectra. The method, called the Gaussian process Hilbert transform (GP-HT), leverages Gaussian processes that are constrained to comply with the HT. The GP-HT, which is an infinite-dimensional generalization of previously developed Bayesian HT, is used to predict the credible intervals of the real part of the EIS spectrum from its imaginary component. The quality of the measurements can then be assessed by benchmarking the prediction against the real part of the experimental EIS spectrum. It is foreseen that, as a new approach for calculating the HT, the GP-HT will stimulate more research on the probabilistic interpretation of the EIS and its consistency.

关键词： BiVO4   Doping   Heterojunction   Molybdenum   Photoconversion   Water oxidation  

摘要： Metal-doping is widely used to enhance charge generation and reduce carrier recombination of BiVO4 for catalyzing water oxidation. In this work, different Mo-doping levels are applied to synthesize Mo-doped BiVO4 (MBVO) on conductive glasses. Molybdenum plays multiple roles of dopant, structure-confined mediator, and sources for forming additional semiconductor. The MBVO with lower Mo-doping levels presents bi-layered structure with nanowire overlayer and nanorod underlayer, which can develop facile one-dimensional charge-transfer paths and efficient heterojunction. With preferable design of nanowire and nanorod layers, the high light absorption, small charge-transfer resistance and high carrier density are attained for MBVO with 1% Mo-doping, which shows the highest photocurrent density of 2.5 mA/cm(2) at 1.23 V-RHE, smallest onset potential of 0.22 V-RHE and highest maximum photoconversion efficiency of 2.20%. This work carefully illustrates the function of molybdenum and firstly constructs the unique bi-layered structure for MBVO to display outstanding photoelectrochemical performance for catalyzing water oxidation. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

关键词： Sugar beet wastewater   Electrooxidation   Electrochemical peroxidation   Response surface methodology   Reaction rate constant  

摘要： Sugar production is a water intensive process that produces a large amount of wastewaters with high concentration of chemical oxygen demand (COD), mostly consists of organic carbon compounds. Conventional treatment methods are limited to provide the necessary treatment of effluent COD to meet the regulatory limits prior to discharge. The treatment performance of electro-oxidation (EO) and electrochemical peroxidation (ECP) for organic removal were investigated in a laboratory scale study. The experimental conditions were optimized for both EO and ECP using Box-Behnken Design (BBD) and the models provided highly significant quadratic models for both treatment methods. The effects of pH, H2O2 dosage, current density, and operation time were investigated using BBD. The results showed that EO could remove 75% of organics at optimum conditions of pH 5.3;current density of 48.5 mA cm(-2);and operation time of 393 min. The predicted values were in reasonable agreement with measured values. ECP could remove total and soluble COD and total and dissolved organic carbon by 65, 64, 66, and 63%, respectively at optimum conditions of H2O2 dosage of 21 mL L-1;current density of 48 mA cm(-2);and operation time of 361 min. The methods were compared based on removal efficiency and energy consumption during operation. (C) 2019 Elsevier Ltd. All rights reserved.

关键词： Zinc oxide  

摘要： O-Polar ZnO(0001) single crystals and ZnO and Mg-doped ZnO (MgZnO) films which were subsequently deposited on the ZnO crystals by a pulsed laser deposition (PLD) method were electrochemically investigated through the interfaces with ionic liquid (IL) in a vacuum. The sample surfaces were confirmed to be atomically clean and flat by reflection high energy electron diffraction (RHEED) observation, prior to their electrochemical measurements. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were then performed, and the donor density, flat band potential of these ZnO samples, and the electric double layer capacitance at the IL/ZnO interfaces were successfully evaluated. The flat band potentials of ZnO and MgZnO films were found to shift to more negative potentials relative to those of the single crystal ZnO, with different values for thicker films, respectively. Some possible origins of the different flat band potentials between ZnO and MgZnO films, and their film thickness dependence of the flat band potential will be discussed in this paper.

关键词： Electro-oxidation   Urea   Mixed metal oxide   Energy consumed   Box-Behnken design   Optimization  

摘要： The present study investigates the electro-oxidation (EO) treatment of urea containing wastewater using mixed metal oxide (MMO) anodes. Box-Behnken design (BBD) was employed to analyze the effects of various operational process parameters like current density (j), NaCl dose (n), treatment time (t) and pH in an EO reactor in batch mode. The performance of the treatment process was evaluated in terms of % degradation and energy consumption. Under optimum conditions, the experimental results showed that more than 94.78% of degradation of urea was achieved. Electro-oxidation has effectively reduced the TOC (90%) under optimum conditions. Attempts were made to integrate the two process electro-oxidation and photocatalysis i.e. Photoelectrocatalysis within the same treatment unit for the enhanced degradation of target pollutant. The electro-oxidation process with mixed metal oxide anode has also attained a significant removal of nitrogen by transforming into the NO3- and NH4+ through the formation of OH center dot and reactive chlorine species. Characterization techniques like SEM-EDX and XRD have confirmed the durability of mixed metal oxide anodes even after 90 recycles of the experimental run. The total operating cost for electro-oxidation treatment of urea under optimized conditions is found to be 0.78 $/m(3). (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

摘要： INTRODUCTION Fluoride in drinking water is an inorganic anion and is among the most important elements for human health.1-3 The World Health Organization (WHO) guideline for the upper limit of fluoride in drinking water is between 1-1.5 mg.L-1.4 Excessive amounts result in various diseases such as dental and skeletal fluorosis, endocrine disruption, reproductive decline, immunopathy, decreasing intelligence quotient (IQ), and effects on hypertension as well as birth height and weight.5-11 Fluoride is found in the wastes and air from various industrial activities, especially electroplating, and the production of semiconductors, glass, steel, ceramics, and chemical fertilizers.1216 In Iran, the fluoride concentration in several areas is higher than 1.5 mg.L-1.17,18 Various methods are used to reduce the fluoride level in water.19-28 The electrochemical method has many advantages such as low operating cost, the capability of being used for a wide range of organic and inorganic pollutants, less contact time, and higher charged flocks entering the stilling basin.29 As a result of the health risks of high fluoride concentrations in drinking water and the mentioned benefits of the electrochemical process, the current study aimed to investigate the application of electrochemical processes to fluoride removal from artificially polluted water. According to the multiple linear regression model, to remove fluoride by the electrochemical process, the main effective factor on removing fluoride is the amount of electrical energy (P<0.001) while the initial concentration of fluoride has less effect on the removal efficacy (P=0.184). (ProQuest: ... denotes formula omitted.) Where: R = Fluoride removal efficiency E = electrical energy (kWh) Fjnjtjai = initial fluoride concentration (mg/L) CONCLUSION This research investigated the performance of the electrochemical process with aluminum electrodes, for fluoride removal from polluted water. At these current densities, the initial fl

关键词： Electro-oxidation process   Adsorption treatment   Ciprofloxacin   Caenorhabditis elegans   Detoxification   Environmental water  

摘要： Pharmaceutical-based contaminants are the major reasons for morbidity and mortality in aquatic animals and lead to several side effects and diseases in human community. Availability of proper, efficient, and cost-effective treatment technologies is still scarce. In this study, an efficient combined treatment technique (electrochemical oxidation and adsorption processes) was developed for the complete detoxification of most commonly used antibiotic, ciprofloxacin in aqueous solution. Electrochemical degradation of ciprofloxacin was performed using titanium-based tri-metal oxide mesh type anode, and the effective oxidative potential, electrolysis time, and pH for the degradation of ciprofloxacin were thoroughly evaluated. Sulfate, fluoride ions and toxic byproducts generated during electrochemical oxidation of ciprofloxacin were subsequently removed through a simple adsorption treatment using activated charcoal for 90 min. Further, the toxicity of the treated water was assessed with the nematode Caenorhabditis elegans species at different time intervals by observing the expressions of important stress-responsive genes viz., sod-3, hsp-16.2, ctl-1,2,3 and gst-4. The results exhibited that the combined process of electrochemical oxidation and adsorption treatment is simple, low-cost as well as effective to eliminate ciprofloxacin and its toxic byproducts in aqueous solution.

关键词： reverse osmosis concentrate   sanitary landfill leachate   anodic oxidation   electro-Fenton   electrocoagulation  

摘要： Electrochemical technologies have been broadly applied in wastewaters treatment, but few studies have focused on comparing the performance of the different electrochemical processes, especially when used to treat highly-polluted streams. The electrochemical treatment of a reverse osmosis concentrate of sanitary landfill leachate was performed by means of electrocoagulation (EC), anodic oxidation (AO) and electro-Fenton (EF) processes, and the use of different electrode materials and experimental conditions was assessed. All the studied processes and experimental conditions were effective in organic load removal. The results obtained showed that EC, with stainless steel electrodes, is the cheapest process, although it presents the disadvantage of sludge formation with high iron content. At high applied current intensity, AO presents the best treatment time/energy consumption ratio, especially if the samples' initial pH is corrected to 3. However, pH correction from natural to 3 deeply decreases nitrogen-containing compounds' removal. For longer treatment time, the EF process with a carbon-felt cathode and a BDD anode, performed at natural iron content and low applied current intensity, is the most favorable solution.

关键词： Indium-tin oxide   Electrochemistry   Dissolution reaction   Tungsten oxide   Electrochromism  

摘要： Recent work has shown that electrochromic WO3 films, backed by In2O3:Sn (ITO) and immersed in a lithium-ion-conducting electrolyte, can attain unprecedented electrochemical cycling durability after potentiostatic pretreatment at high voltage. Here we demonstrate that this intriguing feature is associated with changes in the properties of the ITO film. Specifically, we studied thin films of ITO and WO3/ITO immersed in an electrolyte of LiClO4 in propylene carbonate at potentials up to 6.0 V vs. Li/Li+ by cyclic voltammetry and impedance spectroscopy and present evidence that electrochemical reactions occur under these conditions. X-ray photoemission spectroscopy indicated that the ITO film was partly dissolved at high voltages and that the dissolution reaction promoted diffusion of In and Sn into the WO3 film.