Response Surface Analysis of Fenobucarb Removal by Electrochemically Generated Chlorine

The aim of the present study was to investigate the electrochemical formation of active chlorine and its subsequent use for the degradation of the pesticide fenobucarb. Initially, the process of electrochemical active chlorine production was investigated using an electrochemical flow-cell with a Ti/RuO2 plate electrode. The contribution of four main factors (chloride concentration, current density, the retention time of chloride in the cell (flow rate), and initial pH of inlet solution) to form active chlorine was determined by a central composite design (CCD). The influence of the four variables was statistically significant, and the contributions of flow rate, chloride concentration, pH, and current density were found to be 37.2%, 33.59%, 18.28%, and 10.93%, respectively. A mathematical model was established to predict and optimize the operating conditions for fenobucarb removal in the NaCl electrolysis process. The main transformation products (seven compound structures) were detected by liquid chromatography coupled with high-resolution mass spectrometry (LC–HRMS). The results of the model and transformation products indicated that fenobucarb was degraded due to direct oxidation on the electrode surface, and indirectly by active chlorine and other radicals present during the NaCl electrolysis process.

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Chemical–Electrochemical Process Concept for Lead Recovery from Waste Cathode Ray Tube Glass

Materials ◽

10.3390/ma14061546 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1546

Author(s):

Árpád Imre-Lucaci ◽

Melinda Fogarasi ◽

Florica Imre-Lucaci ◽

Szabolcs Fogarasi

Keyword(s):

Flow Rate ◽

Current Density ◽

Complete Recovery ◽

Electrochemical Process ◽

Operating Conditions ◽

General Effect ◽

Optimal Operating ◽

Recirculation Flow ◽

Lead Recovery ◽

Cathode Ray Tube

This paper presents a novel approach for the recovery of lead from waste cathode-ray tube (CRT) glass by applying a combined chemical-electrochemical process which allows the simultaneous recovery of Pb from waste CRT glass and electrochemical regeneration of the leaching agent. The optimal operating conditions were identified based on the influence of leaching agent concentration, recirculation flow rate and current density on the main technical performance indicators. The experimental results demonstrate that the process is the most efficient at 0.6 M acetic acid concentration, flow rate of 45 mL/min and current density of 4 mA/cm2. The mass balance data corresponding to the recycling of 10 kg/h waste CRT glass in the identified optimal operating conditions was used for the environmental assessment of the process. The General Effect Indices (GEIs), obtained through the Biwer Heinzle method for the input and output streams of the process, indicate that the developed recovery process not only achieve a complete recovery of lead but it is eco-friendly as well.

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Physical Parameters Affecting on the Electrode Performance for Proton Exchange Membrane Fuel Cells (PEMFCs)

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1105.320 ◽

2015 ◽

Vol 1105 ◽

pp. 320-324

Author(s):

Chebbi Rachid ◽

Wan Ramli Wan Daud ◽

Beicha Abdellah ◽

Mohd Ambar Yarmo

Keyword(s):

Power Density ◽

Flow Rate ◽

Current Density ◽

Pressure Ratio ◽

Air Flow ◽

Proton Exchange ◽

Operating Conditions ◽

Physical Parameters ◽

Electrode Performance ◽

Hydrogen Flow

Physical parameters effects are considered as sticking point to increase and decrease the electrode performance for PEMFCs, which is related to the electrode structural degradation under diverse operating conditions, such as various air and hydrogen pressures, humidifier temperatures, and air and hydrogen flow rates. The operating for electrode prepared with 20 wt% Pt loaded 0.3 mgPt/cm2 in single cell (25 cm2) showed that diverse parameters as pressures, humidifier temperatures, flow rate of air /hydrogen have an effects on the electrode performance. Results show better power density for high pressure, high air flow rate, and for low humidifier temperature, low H2 flow rate. The increase in pressure ratio results increases in the current density and power density from 91.96 to 99.96 mA/cm2 and from 32.56{mW/cm2} to 35.48 {mW/cm2} for an air/H2 ratio of 1/0.5 bar and 3/2 bar, respectively. The hydrogen and air flow with the stoichiometry coefficient ratio 2/1 is the best value to achieve better performance by a flow rate of 0.3 L/min for H2 and 0.6 L/min for air, which correspond to a current density and power density of 103.96{mA/cm2} and 31.56{mW/cm2}.

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Performance Investigation of Electrochemical Assisted HClO/Fe2+ Process For The Treatment of Landfill Leachate

10.21203/rs.3.rs-888579/v1 ◽

2021 ◽

Author(s):

Zhihong Ye ◽

Fei Miao ◽

Hui Zhang

Keyword(s):

Current Density ◽

Landfill Leachate ◽

Chloride Concentration ◽

Ammonia Nitrogen ◽

Active Chlorine ◽

Bulk Liquid ◽

Applied Current ◽

Promising Alternative ◽

Applied Current Density ◽

Chlorine Generation

Abstract The feasibility of removal of COD and ammonia nitrogen (NH4+-N) from landfill leachate by electrochemical assisted HClO/Fe2+ process is demonstrated for the first time. The performance of active chlorine generation at the anode was evaluated in Na2SO4/NaCl media, and a higher amount of active chlorine was produced at greater chloride concentration and higher current density. The probe experiments confirmed the coexistence of hydroxyl radical (·OH) and Fe(IV)-oxo complex (FeIVO2+) in the HClO/Fe2+ system. The influence of initial pH, Fe2+ concentration and applied current density on COD and NH4+-N abatement was elaborately investigated. The optimum pH was found to be 3.0, and the proper increase in Fe2+ dosage and current density resulted in higher COD removal due to the accelerated accumulation of ·OH and FeIVO2+ in the bulk liquid phase. Whereas, the NH4+-N oxidation was significantly affected by the applied current density because of the effective active chlorine generation at high current, but was nearly independent of Fe2+ concentration. The reaction mechanism of electrochemical assisted HClO/Fe2+ treatment of landfill leachate was finally proposed. The powerful ·OH and FeIVO2+, in concomitance with active chlorine and M(·OH) were responsible for COD abatement and active chlorine played a key role in NH4+-N oxidation. The proposed electrochemical assisted HClO/Fe2+ process is a promising alternative for the treatment of refractory landfill leachate.

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Stabilization of the Speed of the Hydraulic Motor Through Throttle Compensation for Volume Losses

International conference KNOWLEDGE-BASED ORGANIZATION ◽

10.2478/kbo-2020-0126 ◽

2020 ◽

Vol 26 (3) ◽

pp. 126-130

Author(s):

Krasimir Kalev

Keyword(s):

Flow Rate ◽

Hydraulic Drive ◽

Pressure Change ◽

Operating Conditions ◽

Drive System ◽

Inlet Pressure ◽

Schematic Diagram ◽

Hydraulic Characteristics ◽

Hydraulic Motor ◽

Flow Through

AbstractA schematic diagram of a hydraulic drive system is provided to stabilize the speed of the working body by compensating for volumetric losses in the hydraulic motor. The diagram shows the inclusion of an originally developed self-adjusting choke whose flow rate in the inlet pressure change range tends to reverse - with increasing pressure the flow through it decreases. Dependent on the hydraulic characteristics of the hydraulic motor and the specific operating conditions.

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Designs of InGaN Micro-LED Structure for Improving Quantum Efficiency at Low Current Density

Nanoscale Research Letters ◽

10.1186/s11671-021-03557-4 ◽

2021 ◽

Vol 16 (1) ◽

Author(s):

Shiqiang Lu ◽

Jinchai Li ◽

Kai Huang ◽

Guozhen Liu ◽

Yinghui Zhou ◽

...

Keyword(s):

Quantum Efficiency ◽

Current Density ◽

Carrier Transport ◽

Defect Density ◽

Numerical Study ◽

Structure Design ◽

Operating Conditions ◽

Hole Injection ◽

Electron Blocking Layer ◽

Recombination Processes

AbstractHere we report a comprehensive numerical study for the operating behavior and physical mechanism of nitride micro-light-emitting-diode (micro-LED) at low current density. Analysis for the polarization effect shows that micro-LED suffers a severer quantum-confined Stark effect at low current density, which poses challenges for improving efficiency and realizing stable full-color emission. Carrier transport and matching are analyzed to determine the best operating conditions and optimize the structure design of micro-LED at low current density. It is shown that less quantum well number in the active region enhances carrier matching and radiative recombination rate, leading to higher quantum efficiency and output power. Effectiveness of the electron blocking layer (EBL) for micro-LED is discussed. By removing the EBL, the electron confinement and hole injection are found to be improved simultaneously, hence the emission of micro-LED is enhanced significantly at low current density. The recombination processes regarding Auger and Shockley–Read–Hall are investigated, and the sensitivity to defect is highlighted for micro-LED at low current density.Synopsis: The polarization-induced QCSE, the carrier transport and matching, and recombination processes of InGaN micro-LEDs operating at low current density are numerically investigated. Based on the understanding of these device behaviors and mechanisms, specifically designed epitaxial structures including two QWs, highly doped or without EBL and p-GaN with high hole concentration for the efficient micro-LED emissive display are proposed. The sensitivity to defect density is also highlighted for micro-LED.

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The influence of zinc electrode substrate, electrolyte flow rate and current density on zinc-nickel flow cell performance

Electrochimica Acta ◽

10.1016/j.electacta.2021.137890 ◽

2021 ◽

Vol 373 ◽

pp. 137890

Author(s):

David P. Trudgeon ◽

Adeline Loh ◽

Habib Ullah ◽

Xiaohong Li ◽

Vladimir Yufit ◽

...

Keyword(s):

Flow Rate ◽

Current Density ◽

Flow Cell ◽

Cell Performance ◽

Zinc Electrode ◽

Electrolyte Flow ◽

Zinc Nickel

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Photo-degradation of butyl parahydroxybenzoate by using TiO2-supported catalyst

Water Science & Technology ◽

10.2166/wst.2013.117 ◽

2013 ◽

Vol 67 (10) ◽

pp. 2141-2147 ◽

Cited By ~ 13

Author(s):

Patrick Atheba ◽

Patrick Drogui ◽

Brahima Seyhi ◽

Didier Robert

Keyword(s):

Flow Rate ◽

Photocatalytic Oxidation ◽

Supported Catalyst ◽

Operating Conditions ◽

Treatment Efficiency ◽

Optimal Operating ◽

Photo Degradation ◽

Photochemical Process ◽

Recirculation Flow ◽

High Treatment

The present work evaluates the potential of the photocatalysis (PC) process for the degradation of butylparaben (BPB). Relatively high treatment efficiency was achieved by comparison to photochemical process. Prior to photocatalytic degradation, adsorption (AD) of BPB occurred on the titanium dioxide (TiO2)-supported catalyst. AD was described by Langmuir isotherm (KL = 0.085 L g−1, qm = 4.77 mg g−1). The influence of angle of inclination of the reactor, pH, recirculation flow rate and initial concentration of BPB were investigated. The PC process applied under optimal operating conditions (recirculation flow rate of 0.15 L min−1, angle of inclination of 15°, pH = 7 and 5 mg L−1 of BPB) is able to oxidize 84.9–96.6% of BPB and to ensure around 38.7% of mineralization. The Langmuir–Hinshelwood kinetic model described well the photocatalytic oxidation of BPB (k = 7.02 mg L−1 h−1, K = 0.364 L mg−1).

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Flow Features Analysis of Throttle Notches of Proportional Direct Valve

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.189-193.2285 ◽

2011 ◽

Vol 189-193 ◽

pp. 2285-2288

Author(s):

Wen Hua Jia ◽

Chen Bo Yin ◽

Guo Jin Jiang

Keyword(s):

Fluid Flow ◽

Dynamic Behavior ◽

Flow Rate ◽

Discharge Coefficient ◽

3D Models ◽

Operating Conditions ◽

Flow Models ◽

Flow Features ◽

Rate Discharge ◽

Spool Valve

Flow features, specially, flow rate, discharge coefficient and efflux angle under different operating conditions are numerically simulated, and the effects of shapes and the number of notches on them are analyzed. To simulate flow features, 3D models are developed as commercially available fluid flow models. Most construction machineries in different conditions require different actions. Thus, in order to be capable of different actions and exhibit good dynamic behavior, flow features should be achieved in designing an optimized proportional directional spool valve.

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Experimental Investigation and Modeling of Inertance Tubes

Journal of Fluids Engineering ◽

10.1115/1.1989369 ◽

2005 ◽

Vol 127 (5) ◽

pp. 1029-1037 ◽

Cited By ~ 6

Author(s):

L. O. Schunk ◽

G. F. Nellis ◽

J. M. Pfotenhauer

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Acoustic Power ◽

Operating Conditions ◽

Thermodynamic Efficiency ◽

Pulse Tube ◽

Design Charts ◽

Wide Range ◽

Pulse Tube Refrigerators

Growing interest in larger scale pulse tubes has focused attention on optimizing their thermodynamic efficiency. For Stirling-type pulse tubes, the performance is governed by the phase difference between the pressure and mass flow, a characteristic that can be conveniently adjusted through the use of inertance tubes. In this paper we present a model in which the inertance tube is divided into a large number of increments; each increment is represented by a resistance, compliance, and inertance. This model can include local variations along the inertance tube and is capable of predicting pressure, mass flow rate, and the phase between these quantities at any location in the inertance tube as well as in the attached reservoir. The model is verified through careful comparison with those quantities that can be easily and reliably measured; these include the pressure variations along the length of the inertance tube and the mass flow rate into the reservoir. These experimental quantities are shown to be in good agreement with the model’s predictions over a wide range of operating conditions. Design charts are subsequently generated using the model and are presented for various operating conditions in order to facilitate the design of inertance tubes for pulse tube refrigerators. These design charts enable the pulse tube designer to select an inertance tube geometry that achieves a desired phase shift for a given level of acoustic power.

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Investigation of Biotransformation Products of p-Methoxymethylamphetamine and Dihydromephedrone in Wastewater by High-Resolution Mass Spectrometry

Metabolites ◽

10.3390/metabo11020066 ◽

2021 ◽

Vol 11 (2) ◽

pp. 66

Author(s):

Juliet Kinyua ◽

Aikaterini K. Psoma ◽

Nikolaos I. Rousis ◽

Maria-Christina Nika ◽

Adrian Covaci ◽

...

Keyword(s):

Mass Spectrometry ◽

Wastewater Treatment Plants ◽

High Resolution Mass Spectrometry ◽

Transformation Products ◽

New Psychoactive Substances ◽

Batch Reactors ◽

Flight Mass Spectrometry ◽

Detection And Identification ◽

Wastewater Samples ◽

Set Up

There is a paucity of information on biotransformation and stability of new psychoactive substances (NPS) in wastewater. Moreover, the fate of NPS and their transformation products (TPs) in wastewater treatment plants is not well understood. In this study, batch reactors seeded with activated sludge were set up to evaluate biotic, abiotic, and sorption losses of p-methoxymethylamphetamine (PMMA) and dihydromephedrone (DHM) and identify TPs formed during these processes. Detection and identification of all compounds was performed with target and suspect screening approaches using liquid chromatography quadrupole-time-of-flight mass spectrometry. Influent and effluent 24 h composite wastewater samples were collected from Athens from 2014 to 2020. High elimination rates were found for PMMA (80%) and DHM (97%) after a seven-day experiment and degradation appeared to be related to biological activity in the active bioreactor. Ten TPs were identified and the main reactions were O- and N-demethylation, oxidation, and hydroxylation. Some TPs were reported for the first time and some were confirmed by reference standards. Identification of some TPs was enhanced by the use of an in-house retention time prediction model. Mephedrone and some of its previously reported human metabolites were formed from DHM incubation. Retrospective analysis showed that PMMA was the most frequently detected compound.

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