Selective adsorption of monovalent cations in porous electrodes

2020 ◽  
Vol 22 (43) ◽  
pp. 25184-25194
Author(s):  
Kenji Kiyohara ◽  
Yuji Yamamoto ◽  
Yusuke Kawai
Keyword(s):  
Pore Size ◽  
Applied Voltage ◽  
Selective Adsorption ◽  
Porous Electrodes ◽  
Monovalent Cations ◽  
Hydrated Ions

Selective adsorption of hydrated ions in porous electrodes is controlled by the pore size and the applied voltage.

scholarly journals Advancement of Measurement Techniques for Tunable Resistive Pulse Sensing

2021 ◽  
Author(s):  
◽  
Eva Weatherall
Keyword(s):  
Surface Charge ◽  
Pore Size ◽  
Applied Voltage ◽  
Particle Surface ◽  
Streaming Potential ◽  
Pore Surface ◽  
Size Distributions ◽  
Ζ Potential ◽  
Resistive Pulse ◽  
Tunable Resistive Pulse Sensing

<p>Tunable resistive pulse sensing (TRPS) is a particle-by-particle analysis technique combining the Coulter principle with size-tunable pores. TRPS can be used to characterize biological and synthetic particles 50 nm - 20 µm in diameter. Information is obtained from the resistive pulse signal, a transient change in ionic current observed when a particle passes through the pore. TRPS has been shown to provide excellent resolution and accuracy for measuring particle size and concentration as well as providing information about particle charge. TRPS is therefore applicable to many industrial and fundamental research areas involving aptamers, drug delivery particles, extracellular vesicles and other biological particle types. Advancement of this technology requires a better understanding of the technique, particularly in the area of particle surface charge measurement and this Thesis helps to provide that understanding.  In this work, firstly particle ζ-potential measurement using TRPS was investigated. A number of different measurement methods are presented and the uncertainties associated with each method are outlined. The ζ-potential for a variety of particles with different surface charges were measured in a range of electrolytes.  Particle ζ-potential measurements were then improved upon with the addition of streaming potential measurements to measure the pore surface charge. The ζ-potential of the pore surface, which makes a significant contribution to particle ζ-potential calculations, was measured using a set up which works alongside the qNano. Streaming potential measurements were also used to investigate changes in the pore surface charge following application of number of different chemical coatings. The volume of data collected and detail of analysis in this work (including uncertainties) is unprecedented in TRPS ζ potential measurements.  Biphasic pulses arising from the charge on the particles were investigated. The pulse is conventionally resistive, but biphasic pulses which include both resistive and conductive components are significant for less than 50 mM salt concentrations when measuring 200 nm particles. The experimental variables investigated include the concentration of the electrolyte, particle charge, pore size, applied voltage, and the direction of particlemotion. Conductive pulse size was seen to decrease with increasing electrolyte concentration and pore size and increase with applied voltage. A linear relationship was found between conductive pulse magnitude and particle surface group density. The influence of direction of motion on conductive pulses was consistent with concentration polarization of an ion selective pore. Biphasic pulses were also seen to affect conventional TRPS particle size measurements.  Finally, size distribution broadening due to varying particle trajectories was investigated. Pulse size distributions for monodisperse particles became broader when the pore size was increased and featured two distinct peaks. Relatively large pulses are produced by particles with trajectories passing near to the edge of the pore. Other experiments determined that pulse size distributions are independent of applied voltage but broaden with increasing pressure applied across the membrane.</p>

scholarly journals Advancement of Measurement Techniques for Tunable Resistive Pulse Sensing

2021 ◽  
Author(s):  
◽  
Eva Weatherall
Keyword(s):  
Surface Charge ◽  
Pore Size ◽  
Applied Voltage ◽  
Particle Surface ◽  
Streaming Potential ◽  
Pore Surface ◽  
Size Distributions ◽  
Ζ Potential ◽  
Resistive Pulse ◽  
Tunable Resistive Pulse Sensing

<p>Tunable resistive pulse sensing (TRPS) is a particle-by-particle analysis technique combining the Coulter principle with size-tunable pores. TRPS can be used to characterize biological and synthetic particles 50 nm - 20 µm in diameter. Information is obtained from the resistive pulse signal, a transient change in ionic current observed when a particle passes through the pore. TRPS has been shown to provide excellent resolution and accuracy for measuring particle size and concentration as well as providing information about particle charge. TRPS is therefore applicable to many industrial and fundamental research areas involving aptamers, drug delivery particles, extracellular vesicles and other biological particle types. Advancement of this technology requires a better understanding of the technique, particularly in the area of particle surface charge measurement and this Thesis helps to provide that understanding.  In this work, firstly particle ζ-potential measurement using TRPS was investigated. A number of different measurement methods are presented and the uncertainties associated with each method are outlined. The ζ-potential for a variety of particles with different surface charges were measured in a range of electrolytes.  Particle ζ-potential measurements were then improved upon with the addition of streaming potential measurements to measure the pore surface charge. The ζ-potential of the pore surface, which makes a significant contribution to particle ζ-potential calculations, was measured using a set up which works alongside the qNano. Streaming potential measurements were also used to investigate changes in the pore surface charge following application of number of different chemical coatings. The volume of data collected and detail of analysis in this work (including uncertainties) is unprecedented in TRPS ζ potential measurements.  Biphasic pulses arising from the charge on the particles were investigated. The pulse is conventionally resistive, but biphasic pulses which include both resistive and conductive components are significant for less than 50 mM salt concentrations when measuring 200 nm particles. The experimental variables investigated include the concentration of the electrolyte, particle charge, pore size, applied voltage, and the direction of particlemotion. Conductive pulse size was seen to decrease with increasing electrolyte concentration and pore size and increase with applied voltage. A linear relationship was found between conductive pulse magnitude and particle surface group density. The influence of direction of motion on conductive pulses was consistent with concentration polarization of an ion selective pore. Biphasic pulses were also seen to affect conventional TRPS particle size measurements.  Finally, size distribution broadening due to varying particle trajectories was investigated. Pulse size distributions for monodisperse particles became broader when the pore size was increased and featured two distinct peaks. Relatively large pulses are produced by particles with trajectories passing near to the edge of the pore. Other experiments determined that pulse size distributions are independent of applied voltage but broaden with increasing pressure applied across the membrane.</p>

scholarly journals Electrochemical removal of zinc and nickel ions from wastewater using porous electrodes

2021 ◽  
Author(s):  
Qazi Sabir
Keyword(s):  
Applied Voltage ◽  
Electrochemical Cell ◽  
Operating Conditions ◽  
Porous Electrodes ◽  
Nickel Ions ◽  
Porous Aluminum ◽  
Liquid Flux ◽  
Flow Through ◽  
Simulated Wastewater ◽  
Aluminum Plates

Simulated wastewater containing Ni++ and Zn++ was treated using an electrochemical cell. Porous aluminum cathode and porous stainless steel anode were used in a flow-through configuration. For porous catholdes, both aluminium foam and corrugated aluminum plates having perforations were used. To study the effects of applied voltage and volumetric liquid flux on the removal of Ni++ and Zn++, the electrochemical cell was operated for 48 hours at different applied voltages of 5, 10, 15, 20 and 25 V, and at different volumetric liquid fluxes both in the laminar (0.00471 and 0.00943 m³.m-².s-¹) and turbulent regimes (0.01414, 0.01886 and 0.02357 m³.m-².s-¹). For the maximum removal of both nickel and zinc ions, the optimum applied voltage and volumetric liquid flux were found to be 12 V and 0.02357 m³.m-².s-¹, respectively; under these operating conditions, the concentrations of Ni++ and Zn++ in the simulated wastewater were reduced by 85.5% and 98%, respectively. Operating beyond an applied voltage of 12 V, the removal of Zn++ was slightly improved and achieved a maximum value of 99.05% at 25 V; however, an opposite trend was observed in case of Ni++ removal, which finally decreased to 56% at 25 V., because of the excessive precipitation of Ni++ as nickel hydoroxide.

scholarly journals Polysulfone Influence on Au Selective Adsorbent Imprinted Membrane Synthesis with Sulfonated Polyeugenol as Functional Polymer

Membranes ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 390
Author(s):  
Muhammad Cholid Djunaidi ◽  
Nor Basid Adiwibawa Prasetya ◽  
Arini Khoiriyah ◽  
Pardoyo Pardoyo ◽  
Abdul Haris ◽  
...  
Keyword(s):  
Metal Ions ◽  
Pore Size ◽  
Selective Adsorption ◽  
Mixed Solution ◽  
Membrane Synthesis ◽  
Functional Polymer ◽  
Membrane Selectivity ◽  
Mixed Solutions ◽  
Selective Adsorbent ◽  
Imprinted Membrane

An ionic imprinted membrane (IIM) was synthesized using sulfonated polyeugenol, derived from eugenol, as its functional polymer and polysulfone as its base membrane for the selective adsorption of Au(III). This study aims to determine the adsorption of Au(III) metal ions using IIM compared with the non-imprinted membrane (NIM) and to figure out the membrane selectivity towards Au(III) in mixed solutions of Au/Cd, Au/Cu, and Au/Fe. IIM has a pore size of 0.767 μm while the non-imprinted membrane (NIM) has a pore size of 0.853 μm. The best adsorption result was obtained in the variation of the membrane with the addition of 3.84 g of polysulfone that had pores according to the size of Au. The selectivity results of the Au/Cd mixture solution in NIM and IIM were 17.802 and 36.265. In the mixture of Au/Cu, the NIM and IIM selectivity was 2.386 and 6.886, and in the mixed solution of Au/Fe, the selectivity of NIM and IIM was 0 and 8.489. Thus, the selectivity of IIM towards Au is bigger than NIM.

Effects of Applied Voltages on Micro-Arc Oxidized Coatings of Magnesium Alloy AZ91D in Aluminate Solution

2010 ◽  
Vol 154-155 ◽  
pp. 471-474 ◽  
Author(s):  
Wei Yi Mu ◽  
Rui Xue Luo ◽  
Zheng Xian Li ◽  
Ji Hong Du ◽  
Zheng Ping Xi
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Pore Size ◽  
Applied Voltage ◽  
Significant Variation ◽  
Aluminate Solution ◽  
Alloy Az91d ◽  
Lower Porosity ◽  
Micro Arc Oxidation

Micro-arc oxidation coatings were prepared on magnesium alloy AZ91D substrates at the different applied voltages in aluminate solution. The morphologies, phase components, and corrosion resistances of the coatings were investigated. The effect of the applied voltages on the microstructure and corrosion resistance of the coatings was also discussed. The results indicate that the coatings are uniform in thickness, and mainly composed of MgAl2O4 and MgO. There were many residual discharging channels on the coatings surface. The coatings improved the corrosion resistances of magnesium alloy AZ91D considerably. With the increase of the applied voltage, the thickness and the MgAl2O4 content of the coatings increase, while no significant variation is observed in the MgO content. The coatings surface becomes lower porosity and larger pore size with increasing of the applied voltage. In addition, the corrosion resistances of the coatings on magnesium alloy AZ91D surface are obviously superior to the magnesium alloy AZ91D substrate in the 3.5 wt. % NaCl solutions, and the effect is more remarkable at higher voltage.

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