Determination of limiting current density for different electrodialysis modules

2014 ◽  
Vol 68 (3) ◽  
Author(s):  
Natália Káňavová ◽  
Lubomír Machuča ◽  
David Tvrzník
Keyword(s):  
Ammonium Nitrate ◽  
Flow Velocity ◽  
Current Density ◽  
Nitrate Concentration ◽  
Nitrate Solution ◽  
Limiting Current ◽  
Linear Flow ◽  
Limiting Current Density ◽  
Ammonium Nitrate Solution ◽  
Linear Flow Velocity

AbstractLimiting current density of ammonium nitrate solution in laboratory-, pilot-, and industrial-scale electrodialysis modules were determined to provide a method for the prediction of the limiting current density of ammonium nitrate solutions at any conditions. The current-voltage curve was measured in each case and the limiting current density was evaluated using the dependence of the derivative, dI/dU, on the electric current, I. The limiting current was determined as a current at which the derivative dI/dU equals zero. The developed method enables not only the prediction of the limiting current density but the limiting cut and limiting flux can be determined concurrently at any linear flow velocity of the diluate and inlet ammonium nitrate concentration. It could help to prevent working in the overlimiting region and to avoid undesirable decrease of current efficiency and pH changes. The limiting cut is the maximal cut that can be obtained at certain linear flow velocity and module geometry irrespective of the inlet ammonium nitrate concentration and it is very useful information when designing a new electrodialysis unit for specific application.

Influence of linear flow velocity and ion concentration on limiting current density during electrodialysis

2020 ◽  
Vol 175 ◽  
pp. 334-340
Author(s):  
Kyung Jin Min ◽  
Eun Joo Oh ◽  
Gabin Kim ◽  
Joo Hyeong Kim ◽  
Jun Hee Ryu ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Current Density ◽  
Ion Concentration ◽  
Limiting Current ◽  
Linear Flow ◽  
Limiting Current Density ◽  
Linear Flow Velocity

scholarly journals Ammonia removal from fertilizer plant effluents by a coupled electrostatic shielding based electrodialysis / electrodeionization process

2013 ◽  
Vol 14 (4) ◽  
pp. 468-476
Keyword(s):  
Electric Field ◽  
Ammonium Nitrate ◽  
Current Density ◽  
Pure Water ◽  
Nitrate Solution ◽  
Ionic Current ◽  
Ammonia Removal ◽  
Fertilizer Plant ◽  
Ammonium Nitrate Solution ◽  
A Current

Electrically and ionically conducting graphite powder beds interposed between the anode and cathode inside an electrolytic setup are used as intermediate bipolar electrodes. The beds cause electric field discontinuity by eliminating the applied electric field locally within their mass and act as electrostatically shielded zones – ion and ionic current sinks and thus ion concentrating compartments, whereas the adjacent compartments become ion depleting compartments. The ion sinks were implemented in a coupled electrostatic shielding electrodialysis/electrodeionization process to remove ammonium nitrate from fertilizer plant wastewaters. The batch wise operated electrostatic shielding electrodialysis of a solution containing 1310 mg L-1 ammonium nitrate produced in 28 min at a current density of 15-30 A m-2 a concentrate ammonium nitrate solution which could be recycled to the fertilizer plant unit and a diluate containing 50 mg L-1 ammonium nitrate. The diluate was subsequently used as feed in the electrostatic shielding electrodeionization process to produce pure water of a NH4 + and NO3- ion concentration of less than 1 mg L-1 respectively with a flow rate of 5.51x10-4 dm3 s-1 and a current density of 50 A m-2.

The Removal of Uranium From Simulated Ammonium Diuranate Filtrate by Nanofiltration

2017 ◽  
Author(s):  
Yuan Zhongwei ◽  
Wang Runci ◽  
Yan Taihong ◽  
Zheng Weifang
Keyword(s):  
Ammonium Nitrate ◽  
Uranium Concentration ◽  
Nitrate Concentration ◽  
Nitrate Solution ◽  
Testing Device ◽  
Permeate Flux ◽  
Ammonium Diuranate ◽  
Ammonium Nitrate Solution ◽  
Crossflow Velocity ◽  
Very High

In this study, a simulated ammonium diuranate filtrate (ADUF) which was obtained by adding uranyl nitrate to a 35 g/L ammonium nitrate solution to adjust the uranium concentration to about 50 mg/L was treated by a nanofiltration process. Experiments were carried out on a plate membrane testing device with a trans-membrane pressure (TMP) range of 0.5 ∼ 3.0 MPa, a crossflow velocity range of 10 ∼ 50 cm/s and a temperature range of 5 ∼ 35 °C. The results show that NF270 membrane has good rejection property for uranium and excellent permeability for ammonium nitrate. The ammonium nitrate concentration in the permeate is about 32 g/L which means the reject ratio of ammonium nitrate is only about 10%. Though NF270 membrane shows good uranium rejection property, the corresponding permeate flux is very high. When the trans-membrane pressure is 1.5 MPa, the uranium reject ratio is 96.8% and the the corresponding permeate flux is about 80 L/(m2·h). It indicates a bright application prospect of nanofiltration process in the treatment of ADUF.

scholarly journals Flow velocity and cell pair number effect on current efficiency in plating wastewater treatment through electrodialysis

2020 ◽  
Vol 26 (2) ◽  
pp. 190502-0
Author(s):  
Kyung Jin Min ◽  
Joo Hyeong Kim ◽  
Eun Joo Oh ◽  
Jun Hee Ryu ◽  
Ki Young Park
Keyword(s):  
Heavy Metals ◽  
Current Efficiency ◽  
Flow Velocity ◽  
Removal Efficiency ◽  
Limiting Current ◽  
Toxic Substances ◽  
Linear Flow ◽  
Design Elements ◽  
Cell Pair ◽  
Linear Flow Velocity

Electrodialysis has been used for treating toxic substances such as heavy metals and minimizing secondary environmental pollution problems effectively. However, electrodialysis depends on the operating parameters as well as fluid dynamics and electrical properties. This study provides design elements for the treatment of heavy metal-containing wastewater by electrodialysis. We found that the limiting current density (LCD) is proportional but not completely linear to the diluate concentration over a threshold value. In contrast, it is linear to the linear flow velocity for the whole range. As the number of cell pairs increases, because linear flow velocity and LCD increase, the removal efficiency of heavy metals also increases. Therefore, for highly concentrated wastewater, increasing the linear flow velocity, the applied voltage, and the number of cell pairs can effectively improve removal efficiency. It was found that the current efficiency is as low as 17% when the removal efficiency of heavy metals exceeds 95%. Thus, it is necessary to select an operating range that optimizes the operating and initial investment costs for the effective removal of heavy metals using electrodialysis.

scholarly journals Limiting Current Density of Oxygen Reduction under Ultrathin Electrolyte Layers: From the Micrometer Range to Monolayers

2021 ◽  
Vol 8 (4) ◽  
pp. 712-718
Author(s):  
Xiankang Zhong ◽  
Matthias Schulz (née Uebel) ◽  
Chun‐Hung Wu ◽  
Martin Rabe ◽  
Andreas Erbe ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Current Density ◽  
Limiting Current ◽  
Limiting Current Density

scholarly journals Demineralization of Rehydrated Cheese Whey by Electrodialysis. Effects of deashing rates and solid concentration on limiting current density.

1991 ◽  
Vol 17 (5) ◽  
pp. 1006-1011 ◽  
Author(s):  
Yasunobu Hiraoka ◽  
Akira Tomizawa ◽  
Tatsuki Oguchi ◽  
Etsuko Suzuki ◽  
Masanobu Koutake
Keyword(s):  
Current Density ◽  
Cheese Whey ◽  
Limiting Current ◽  
Solid Concentration ◽  
Limiting Current Density

Degradation of Materials Based on Alkali-Activated Blast-Furnace Slag after Exposure to Aggressive Environments

2021 ◽  
Vol 325 ◽  
pp. 131-136
Author(s):  
Iveta Plšková ◽  
Petr Hrubý ◽  
Libor Topolář ◽  
Michal Matysík
Keyword(s):  
Blast Furnace ◽  
Ammonium Nitrate ◽  
Sodium Sulfate ◽  
Blast Furnace Slag ◽  
Nitrate Solution ◽  
Ammonium Nitrate Solution ◽  
Degradation Of Materials ◽  
Non Destructive ◽  
Furnace Slag ◽  
Alkali Activated

The paper summarizes partial results of a study of degradation of materials based on alkali-activated blast-furnace slag (AAS) and comparative on cement CEM III/A 32.5 R after exposure to aggressive environments. It further specifies the possibilities for utilising destructive and non-destructive techniques to determine the progress of degradation and characterizes the degree of their correlation. After 28 days of ageing in a water environment, the produced test specimens (40×40×160 mm beams) were placed in aggressive media (ammonium nitrate solutions; sodium sulfate, rotating water) and after subsequent 28, 56 and 84 days of degradation were subjected to testing. Testing comprised both a destructive form (determination of compressive strength and flexural strength) and a selected non-destructive technique (Impact-echo method). The partial outputs were supplemented by the results acquired from monitoring weight changes. In addition, the development of Ultrasonic Pulse Velocity in relation to the progress of the degradation processes was also monitored. While the exposure of both test specimens to water and sodium sulfate did not result in any significant changes, the exposure to the ammonium nitrate solution exhibited rapid signs of degradation associated with a significant reduction in functional characteristics.

Polarization Characteristics to Wear Ratio of Anti-Fouling Paint

2015 ◽  
Vol 1110 ◽  
pp. 179-184
Author(s):  
Kyung Man Moon ◽  
Dong Hyun Park ◽  
Yun Hae Kim ◽  
Tae Sil Baek
Keyword(s):  
Current Density ◽  
Corrosion Potential ◽  
Wear Test ◽  
Life Time ◽  
Point Of View ◽  
Limiting Current ◽  
Limiting Current Density ◽  
Wear Ratio ◽  
Polarization Characteristics ◽  
Lower Variation

Recently, anti-fouling paints which does not include the poison components such as tin (Sn) free, copper (Cu) free have been increasingly developed in order to decrease the contamination of marine environment. Moreover, the wear ratios of these anti-fouling paints are very important problem to prolong their life time in economical and environmental point of view. In this study, four types of anti-fouling paints as self-polishing type were investigated on the relationship between their polarization characteristics and wear ratios. Relationship between wear ratio and variation ratio of polarization resistance measured in corrosion potential was not well matched with each other. However, there was a good agreement between the wear ratio and variation ratio of diffusion limiting current density, for example, the higher or the lower variation ratio of diffusion limiting current density, wear ratio also increased or decreased respectively. Consequently, it is suggested that we can qualitatively expect the life time and wear degree of anti-fouling paint by only measuring the polarization characteristics before the wear test is practically performed in the field.Keywords: Anti-fouling paint, Self-polishing type, Polarization characteristics, Wear ratio, Diffusion limiting current density, Corrosion Potential

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