The determination of bubble size distribution is a prerequisite for the study of gas-liquid two-phase flow characteristics in electrolytic cells.Here the departure diameter of hydrogen bubbles and oxygen bubbles and t...The determination of bubble size distribution is a prerequisite for the study of gas-liquid two-phase flow characteristics in electrolytic cells.Here the departure diameter of hydrogen bubbles and oxygen bubbles and their detachment process from a nickel wire electrode during water electrolysis are studied using high-speed photography.The results show that in industrial alkaline environment,the departure diameters of most hydrogen bubbles and oxygen bubbles are generally smaller than 60μm and 250μm with the current density ranges from 0.15 to 0.35A/cm^(2).The adhesion force of hydrogen bubbles on a nickel wire is found to be so weak that they can separate with a tiny size.The diameters of oxygen bubbles conform to normal distribution,and its distribution range widens with the increase of current density.The theoretical analysis show that the comprehensive conversion rate of current-to-bubble is unexpectedly low especially at low current densities,which may be attributed to the loss of gas components caused by bubble detachment mode.The majority of oxygen bubbles detach by a sudden bounce after coalescence,which may bring strong disturbance to the concentration boundary layer.This also indicates the coalescence-induced bubble departure mode may occupy a dominant position in the electrolyzers.展开更多
The purpose of this research was to fmd out effectiveness of chloride solid membrane electrode of coated wire system compared to solid membrane electrode of composite system, the Nernstian response and character＇s po...The purpose of this research was to fmd out effectiveness of chloride solid membrane electrode of coated wire system compared to solid membrane electrode of composite system, the Nernstian response and character＇s potential response （detection limit, selectivity and response time）. The chloride ISEs （ion selective electrodes） in this research were the solid membrane chloride ISEs based AgC1. There were two types of chloride ISEs that were developed, namely the chloride ISEs of coated wire and composite systems. Both types of electrodes were characterized. The selectivity was done by comparing Esel of the chloride standard solutions and Esel of the interference ions （Br- and I-）. The measurement of chloride ions in water samples was done by using the coated wire chloride ISE, the composite chloride ISE and the Mohr method. We compared the result of the two chloride ISE methods to that of standard method for chloride determination （Mohr） by using F-test and Post Hoc Test LSD （least significant difference） and Duncan. Analysis by using F-test and Post Hoc Test （LSD and Duncan） and characterization results of both the methods showed that coated wire chloride ISE was more effective compared to composite chloride ISE. Nemstian response was 59.83 mV/decade, linier range measurement was 10-1-10-5 M, limit detection was 1.23 × 10-5 M, response time along was 25 s and interfering ion was 10-4 M Br-.展开更多
Coated wire sensor for potentiometric determination ofDAP （dapoxetine HCI） in pure form and in biological fluidsbased on DAP-TPB （dapoxetine-tetraphenyl borate） as the sensing element in the presence of DOP （dioc...Coated wire sensor for potentiometric determination ofDAP （dapoxetine HCI） in pure form and in biological fluidsbased on DAP-TPB （dapoxetine-tetraphenyl borate） as the sensing element in the presence of DOP （dioctylphthalate） as the plasticizing solvent mediator was prepared. The best performance was obtained with a membrane composition of 10.0% （w/w） ion-pair, 45.0% DOP （w/w） and 45.0% PVC （w/w）. The electrode showed a Nemstian response （with a slope of 58.70 mV decade-1） for the concentration range of 4.2 × 10-5-1.0 ×10-2 mol/L. It illustrates a relatively fast response time in the whole concentration range （-15 s） in a pH range of 3.0-7.5. The selectivity coefficients were determined in relation to several inorganic and organic species. DAP is determined successfully in pure solutions and in biological fuids using the standard additions and petentiometric titrations methods.展开更多
The current distributions over carbon steel under iron red alkyd primer exposed to 3.5% sodium chloride solution were mapped using the wire beam electrode （WBE）. The electrochemical impedance spectroscopy （EIS） of...The current distributions over carbon steel under iron red alkyd primer exposed to 3.5% sodium chloride solution were mapped using the wire beam electrode （WBE）. The electrochemical impedance spectroscopy （EIS） of the WBE was carded out to analyze the performance of coating delamination and corrosion behavior of carbon steel beneath defective coating. The EIS data revealed that protective capability of coating decreased with immersion time and the degree of cathodic delamination showed a rapid rise. The current density distribution of WBE indicated that cathodic sites was located at the defect at the beginning of immersion and gradually spread into the intact coating. The cathodic regions were distinguished from the anodic area and distributed over the WBE. The changes of cathodic sites could reflect the deterioration process of defective coating. The cathodic area ratio was a more useful parameter than the cathodic delamination degree to evaluate the coating cathodic delamination. The polarity reversals of electrodes at the defect and beneath coating were observed. A simple discussion of relationship between the blister and the polarity reversal was made from a standpoint of electrochemical distribution. WBE method was able to map and record the changes of local cathodic sites beneath defective coating in real time, which could provide more detailed information about the local degradation of coating.展开更多
The effect of in-situ local damage of uniform porous corrosion products on the localised corrosion of carbon steel is investigated using the wire beam electrode technique(WBE)combined with morphology characterisation ...The effect of in-situ local damage of uniform porous corrosion products on the localised corrosion of carbon steel is investigated using the wire beam electrode technique(WBE)combined with morphology characterisation and electrochemical tests.The WBE measurements demonstrate that the localised corrosion is enhanced by the in-situ local removal of porous corrosion products,supported by the morphology characterisation and electrochemical tests.The enhanced localised corrosion does not originate from the damaged wire in WBE where the corrosion products are removed but from the other undamaged wires,which is reported for the first time.A mechanism is proposed that the intensive anodic polarisation effect of the damaged wire on the undamaged wires could account for the enhanced localised corrosion,which is due to the protective corrosion products newly formed on the damaged surface and the increase in the potential of damaged wire.展开更多
Potentiometric electrodes were developed for the rapid determination of proguanil hydrochloride in pure samples, pharmaceutical preparations and spiked serum and urine samples using PVC membrane,screen printed（SPE）,...Potentiometric electrodes were developed for the rapid determination of proguanil hydrochloride in pure samples, pharmaceutical preparations and spiked serum and urine samples using PVC membrane,screen printed（SPE）, coated wired（CWE）, carbon paste（CPE） and modified carbon paste（MCPE）electrodes based on the ion-exchanger of proguanil with phosphotungestic acid（Pr-PT） as a chemical modifier. The prepared electrodes showed Nernestian slopes of 59.7, 58.1, 58.5, 58.5 and 57.0 for the PVC,SPE, CWE, CPE and MCPE for the proguanil ions in a wide concentration range of 1.0 ＊ 10^-5–1.0 ＊ 10^-2mol L^-1 at 25°C with detection limits of 7.94 ＊ 10^-6, 1.0 ＊ 10^-5, 1.0 ＊ 10^-6, 7.07 ＊ 10^-6 and 2.5 ＊ 10^-6 mol L^-1, respectively. The prepared electrodes exhibited high proguanil selectivity in relation to several inorganic ions and sugars and they could be successfully utilized for its determination in pure solutions, pharmaceutical preparations and serum and urine samples using the direct potentiometry and standard addition methods with very good recovery values.展开更多
The initial corrosion evolution of marine structural steel in tidal zone is studied using wire beam electrode(WBE).The electrochemical experiment results show that the WBE in the high and middle tidal zones are in the...The initial corrosion evolution of marine structural steel in tidal zone is studied using wire beam electrode(WBE).The electrochemical experiment results show that the WBE in the high and middle tidal zones are in the anodic dissolution state for less time than that in the low tidal and immersion zones.The fitting results of WBE experiment provide the boundary conditions for the partitioned cellular automata(PCA)model,which is adopted to simulate the initial corrosion evolutions of steel in the tidal zone.The proposed independent variable of the electrolyte concentration(ρ),corrosion probability(P_(c)),passivation probability(P_(p)),and movement direction probability(P_(m))on the corrosion behavior of steel are studied.The calculated results demonstrate that ρ and P_(m)can well characterize the corrosion evolutions of the steel in ocean tidal zones.This model is effective in predicting the corrosion evolution of marine structural steel in tidal zone.It provides a new method for predicting the corrosion evolution of marine structural steel in tidal zone.展开更多
The study aimed to explore the cathodic protection of the defect areas of 75 wt.%zinc-rich coatings(ZRCs)under immersion and atmospheric thin liquid film conditions using a wire beam electrode(WBE).Besides,electrochem...The study aimed to explore the cathodic protection of the defect areas of 75 wt.%zinc-rich coatings(ZRCs)under immersion and atmospheric thin liquid film conditions using a wire beam electrode(WBE).Besides,electrochemical impedance spectroscopy,scanning electron microscopy,and surface morphology analysis were used.Under both experimental conditions,high ZRCs content polarised the entire electrode to the protective potential range,thereby reversing the polarity of the defect area steel substrate to cathodic to prevent corrosion.The higher concentration of dissolved oxygen in the surface liquid film and coating activated the zinc powder faster and provided a higher cathodic protection current for the defect area under the atmospheric liquid film condition.Therefore,WBE corrosion potential shifted more negative under the atmospheric liquid film condition,thereby conveying longer-lasting cathodic protection and reducing the corrosion rate of the defect area steel substrate.Compared with the traditional sheet electrode,WBE can provide the current distribution and change information of cathodic protection at the local defects on the ZRCs surface,thereby providing a reliable test and a method for evaluating heterogeneous corrosion and cathodic protection.展开更多
基金support by the National Key R&D Program of China(2022YFB4202201)Ordos-Tsinghua Innovative&Collaborative Research Program in Carbon Neutrality,Science and Technology Department of Jiangsu Province under Grand BE2022040Support Plan for Young Excellent Talents of the Department of Energy and Power Engineering,Tsinghua University.
文摘The determination of bubble size distribution is a prerequisite for the study of gas-liquid two-phase flow characteristics in electrolytic cells.Here the departure diameter of hydrogen bubbles and oxygen bubbles and their detachment process from a nickel wire electrode during water electrolysis are studied using high-speed photography.The results show that in industrial alkaline environment,the departure diameters of most hydrogen bubbles and oxygen bubbles are generally smaller than 60μm and 250μm with the current density ranges from 0.15 to 0.35A/cm^(2).The adhesion force of hydrogen bubbles on a nickel wire is found to be so weak that they can separate with a tiny size.The diameters of oxygen bubbles conform to normal distribution,and its distribution range widens with the increase of current density.The theoretical analysis show that the comprehensive conversion rate of current-to-bubble is unexpectedly low especially at low current densities,which may be attributed to the loss of gas components caused by bubble detachment mode.The majority of oxygen bubbles detach by a sudden bounce after coalescence,which may bring strong disturbance to the concentration boundary layer.This also indicates the coalescence-induced bubble departure mode may occupy a dominant position in the electrolyzers.
文摘The purpose of this research was to fmd out effectiveness of chloride solid membrane electrode of coated wire system compared to solid membrane electrode of composite system, the Nernstian response and character＇s potential response （detection limit, selectivity and response time）. The chloride ISEs （ion selective electrodes） in this research were the solid membrane chloride ISEs based AgC1. There were two types of chloride ISEs that were developed, namely the chloride ISEs of coated wire and composite systems. Both types of electrodes were characterized. The selectivity was done by comparing Esel of the chloride standard solutions and Esel of the interference ions （Br- and I-）. The measurement of chloride ions in water samples was done by using the coated wire chloride ISE, the composite chloride ISE and the Mohr method. We compared the result of the two chloride ISE methods to that of standard method for chloride determination （Mohr） by using F-test and Post Hoc Test LSD （least significant difference） and Duncan. Analysis by using F-test and Post Hoc Test （LSD and Duncan） and characterization results of both the methods showed that coated wire chloride ISE was more effective compared to composite chloride ISE. Nemstian response was 59.83 mV/decade, linier range measurement was 10-1-10-5 M, limit detection was 1.23 × 10-5 M, response time along was 25 s and interfering ion was 10-4 M Br-.
文摘Coated wire sensor for potentiometric determination ofDAP （dapoxetine HCI） in pure form and in biological fluidsbased on DAP-TPB （dapoxetine-tetraphenyl borate） as the sensing element in the presence of DOP （dioctylphthalate） as the plasticizing solvent mediator was prepared. The best performance was obtained with a membrane composition of 10.0% （w/w） ion-pair, 45.0% DOP （w/w） and 45.0% PVC （w/w）. The electrode showed a Nemstian response （with a slope of 58.70 mV decade-1） for the concentration range of 4.2 × 10-5-1.0 ×10-2 mol/L. It illustrates a relatively fast response time in the whole concentration range （-15 s） in a pH range of 3.0-7.5. The selectivity coefficients were determined in relation to several inorganic and organic species. DAP is determined successfully in pure solutions and in biological fuids using the standard additions and petentiometric titrations methods.
基金supported by the National Natural Science Foundation of China (Grant No. 51131005)
文摘The current distributions over carbon steel under iron red alkyd primer exposed to 3.5% sodium chloride solution were mapped using the wire beam electrode （WBE）. The electrochemical impedance spectroscopy （EIS） of the WBE was carded out to analyze the performance of coating delamination and corrosion behavior of carbon steel beneath defective coating. The EIS data revealed that protective capability of coating decreased with immersion time and the degree of cathodic delamination showed a rapid rise. The current density distribution of WBE indicated that cathodic sites was located at the defect at the beginning of immersion and gradually spread into the intact coating. The cathodic regions were distinguished from the anodic area and distributed over the WBE. The changes of cathodic sites could reflect the deterioration process of defective coating. The cathodic area ratio was a more useful parameter than the cathodic delamination degree to evaluate the coating cathodic delamination. The polarity reversals of electrodes at the defect and beneath coating were observed. A simple discussion of relationship between the blister and the polarity reversal was made from a standpoint of electrochemical distribution. WBE method was able to map and record the changes of local cathodic sites beneath defective coating in real time, which could provide more detailed information about the local degradation of coating.
基金the Opening Project of Material Corrosion and Protection Key Laboratory of Sichuan Province(No.2017CL18)。
文摘The effect of in-situ local damage of uniform porous corrosion products on the localised corrosion of carbon steel is investigated using the wire beam electrode technique(WBE)combined with morphology characterisation and electrochemical tests.The WBE measurements demonstrate that the localised corrosion is enhanced by the in-situ local removal of porous corrosion products,supported by the morphology characterisation and electrochemical tests.The enhanced localised corrosion does not originate from the damaged wire in WBE where the corrosion products are removed but from the other undamaged wires,which is reported for the first time.A mechanism is proposed that the intensive anodic polarisation effect of the damaged wire on the undamaged wires could account for the enhanced localised corrosion,which is due to the protective corrosion products newly formed on the damaged surface and the increase in the potential of damaged wire.
基金Cairo University for the financial support of this work
文摘Potentiometric electrodes were developed for the rapid determination of proguanil hydrochloride in pure samples, pharmaceutical preparations and spiked serum and urine samples using PVC membrane,screen printed（SPE）, coated wired（CWE）, carbon paste（CPE） and modified carbon paste（MCPE）electrodes based on the ion-exchanger of proguanil with phosphotungestic acid（Pr-PT） as a chemical modifier. The prepared electrodes showed Nernestian slopes of 59.7, 58.1, 58.5, 58.5 and 57.0 for the PVC,SPE, CWE, CPE and MCPE for the proguanil ions in a wide concentration range of 1.0 ＊ 10^-5–1.0 ＊ 10^-2mol L^-1 at 25°C with detection limits of 7.94 ＊ 10^-6, 1.0 ＊ 10^-5, 1.0 ＊ 10^-6, 7.07 ＊ 10^-6 and 2.5 ＊ 10^-6 mol L^-1, respectively. The prepared electrodes exhibited high proguanil selectivity in relation to several inorganic ions and sugars and they could be successfully utilized for its determination in pure solutions, pharmaceutical preparations and serum and urine samples using the direct potentiometry and standard addition methods with very good recovery values.
基金financially supported by the National Natural Science Foundation of China(Nos.51879292 and 51525903)the Guangdong International Science and Technology Cooperation Programme(No.2019A050510020)the 173 Project(No.2020-JCJQ-ZD-233-03),which cooperating with Northeastern University
文摘The initial corrosion evolution of marine structural steel in tidal zone is studied using wire beam electrode(WBE).The electrochemical experiment results show that the WBE in the high and middle tidal zones are in the anodic dissolution state for less time than that in the low tidal and immersion zones.The fitting results of WBE experiment provide the boundary conditions for the partitioned cellular automata(PCA)model,which is adopted to simulate the initial corrosion evolutions of steel in the tidal zone.The proposed independent variable of the electrolyte concentration(ρ),corrosion probability(P_(c)),passivation probability(P_(p)),and movement direction probability(P_(m))on the corrosion behavior of steel are studied.The calculated results demonstrate that ρ and P_(m)can well characterize the corrosion evolutions of the steel in ocean tidal zones.This model is effective in predicting the corrosion evolution of marine structural steel in tidal zone.It provides a new method for predicting the corrosion evolution of marine structural steel in tidal zone.
基金financially supported by the National Natural Science Foundation of China(Nos.21203034 and 51771057)the GF Research and Cultivation Project of Sun Yat-sen University(No.76110–18843406)the National Science and Technology Resources Investigation Program of China(No.2019FY101400)
文摘The study aimed to explore the cathodic protection of the defect areas of 75 wt.%zinc-rich coatings(ZRCs)under immersion and atmospheric thin liquid film conditions using a wire beam electrode(WBE).Besides,electrochemical impedance spectroscopy,scanning electron microscopy,and surface morphology analysis were used.Under both experimental conditions,high ZRCs content polarised the entire electrode to the protective potential range,thereby reversing the polarity of the defect area steel substrate to cathodic to prevent corrosion.The higher concentration of dissolved oxygen in the surface liquid film and coating activated the zinc powder faster and provided a higher cathodic protection current for the defect area under the atmospheric liquid film condition.Therefore,WBE corrosion potential shifted more negative under the atmospheric liquid film condition,thereby conveying longer-lasting cathodic protection and reducing the corrosion rate of the defect area steel substrate.Compared with the traditional sheet electrode,WBE can provide the current distribution and change information of cathodic protection at the local defects on the ZRCs surface,thereby providing a reliable test and a method for evaluating heterogeneous corrosion and cathodic protection.
