PDF Publication Title:
Text from PDF Page: 017
Membranes 2020, 10, 221 17 of 72 Membranes 2020, 10, x FOR PEER REVIEW 18 of 73 Figure 11. Typical current-voltage curve, appearance of electroconvective vortices and intensity of Figure 11. Typical current-voltage curve, appearance of electroconvective vortices and intensity of water molecule dissociation (Adapted from Bazinet and Castaigne [11]). water molecule dissociation (Adapted from Bazinet and Castaigne [11]). The main factors responsible for the development of electroconvection are the electric and/or The main factors responsible for the development of electroconvection are the electric and/or geometric heterogeneities of the membrane surface [78–81], the hydrophobicity of the surface and geometric heterogeneities of the membrane surface [78–81], the hydrophobicity of the surface and its its charge [82], the change in resin/inert binder ratio [77] as well as the concentration distribution charge [82], the change in resin/inert binder ratio [77] as well as the concentration distribution heterogeneity at the membrane/solution interface [72]. All these effects are synergistic and contribute to heterogeneity at the membrane/solution interface [72]. All these effects are synergistic and contribute the appearance of the tangential component of the electric force, which sets the volume of the solution to the appearance of the tangential component of the electric force, which sets the volume of the at the membrane surface in motion [9,52]. Hence, recently, it was observed that for relatively uniform solution at the membrane surface in motion [9,52]. Hence, recently, it was observed that for relatively distribution of widely spaced conducting areas, the vortex size near the membrane surface increased uniform distribution of widely spaced conducting areas, the vortex size near the membrane surface from about 50 to 200 μm for modified membranes; the vortex size being determined by the distance increased from about 50 to 200 μm for modified membranes; the vortex size being determined by the between two neighboring conducting areas [81]. distance between two neighboring conducting areas [81]. 3.4.3. Effects of Overliming Current Conditions on Electrodialytic Process Performances 3.4.3. Effects of Overliming Current Conditions on Electrodialytic Process Performances As demonstrated by recent studies, electroconvective vortices improve ED performances and/or As demonstrated by recent studies, electroconvective vortices improve ED performances and/or cost by (1) facilitating the transport of ions towards the surface of the ion exchange membrane, cost by (1) facilitating the transport of ions towards the surface of the ion exchange membrane, (2) (2) decreasing the surface of membrane needed for the same operation and (3) affecting fouling decreasing the surface of membrane needed for the same operation and (3) affecting fouling formation. Indeed, the electroconvective vortices have the effect of thinning the boundary layer at formation. Indeed, the electroconvective vortices have the effect of thinning the boundary layer at the the surface of the membrane and thus increasing the mass transfer of ion by agitation: the voltage surface of the membrane and thus increasing the mass transfer of ion by agitation: the voltage increase in the ED cell then results in an increase in intensity (Figure 11, overlimiting region) [9]. increase in the ED cell then results in an increase in intensity (Figure 11, overlimiting region) [9]. Besides the improvement in ion transfer, the ED operation with intensive current may reduce the Besides the improvement in ion transfer, the ED operation with intensive current may reduce the membrane area, which is considerably advantageous, since the costs of ion-exchange membranes membrane area, which is considerably advantageous, since the costs of ion-exchange membranes are are generally high; at an industrial scale, the cost of the IEMs and spacers contributes to 25–30% of generally high; at an industrial scale, the cost of the IEMs and spacers contributes to 25–30% of the the total cost of a new ED unit fully automated, but this relative percentage increases when the level total cost of a new ED unit fully automated, but this relative percentage increases when the level of of automation is decreased. On another hand, operating at overlimiting current densities may lead automation is decreased. On another hand, operating at overlimiting current densities may lead to to intense water dissociation at the membrane surface, which favors the deposition of organic and intense water dissociation at the membrane surface, which favors the deposition of organic and inorganic substances on it, fouling and scaling, respectively [65,83,84]: the cost of cleaning procedures inorganic substances on it, fouling and scaling, respectively [65,83,84]: the cost of cleaning procedures and membrane replacement may vary to 40–50% for the electrodialytic processes [85,86]. However, and membrane replacement may vary to 40–50% for the electrodialytic processes [85,86]. However, Bukhovets et al. [87] reported the influence of electroconvection on the prevention of organic fouling Bukhovets et al. [87] reported the influence of electroconvection on the prevention of organic fouling by the “washing” effect of the vortices, while Mikhaylin et al. [88] demonstrated the positive effect of by the “washing” effect of the vortices, while Mikhaylin et al. [88] demonstrated the positive effect of electroconvection on the attenuation of scaling on ion exchange membranes. electroconvection on the attenuation of scaling on ion exchange membranes. The overlimiting regime seems to be an advantageous solution to improve the efficiency of ED The overlimiting regime seems to be an advantageous solution to improve the efficiency of ED processes. However, several aspects must still be studied or taken into account before overlimiting processes. However, several aspects must still be studied or taken into account before overlimiting current conditions can be used at an industrial scale such as (1) electricity costs and production, current conditions can be used at an industrial scale such as (1) electricity costs and production, (2) energy consumption, (3) heat production by Joule effect and (4) impacts of water dissociation and vortices on the membrane integrity in the long term. Indeed, as demonstrated by Mikhaylin et al.PDF Image | Electrodialytic Processes
PDF Search Title:
Electrodialytic ProcessesOriginal File Name Searched:
membranes-10-00221.pdfDIY PDF Search: Google It | Yahoo | Bing
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
IT XR Project Redstone NFT Available for Sale: NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Be part of the future with this NFT. Can be bought and sold but only one design NFT exists. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Turbine IT XR Project Redstone Design: NFT for sale... NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Includes all rights to this turbine design, including license for Fluid Handling Block I and II for the turbine assembly and housing. The NFT includes the blueprints (cad/cam), revenue streams, and all future development of the IT XR Project Redstone... More Info
Infinity Turbine ROT Radial Outflow Turbine 24 Design and Worldwide Rights: NFT for sale... NFT for the ROT 24 energy turbine. Be part of the future with this NFT. This design can be bought and sold but only one design NFT exists. You may manufacture the unit, or get the revenues from its sale from Infinity Turbine. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Supercritical CO2 10 Liter Extractor Design and Worldwide Rights: The Infinity Supercritical 10L CO2 extractor is for botanical oil extraction, which is rich in terpenes and can produce shelf ready full spectrum oil. With over 5 years of development, this industry leader mature extractor machine has been sold since 2015 and is part of many profitable businesses. The process can also be used for electrowinning, e-waste recycling, and lithium battery recycling, gold mining electronic wastes, precious metals. CO2 can also be used in a reverse fuel cell with nafion to make a gas-to-liquids fuel, such as methanol, ethanol and butanol or ethylene. Supercritical CO2 has also been used for treating nafion to make it more effective catalyst. This NFT is for the purchase of worldwide rights which includes the design. More Info
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
Infinity Turbine Products: Special for this month, any plans are $10,000 for complete Cad/Cam blueprints. License is for one build. Try before you buy a production license. May pay by Bitcoin or other Crypto. Products Page... More Info
CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com (Standard Web Page)