{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/104883"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/104883","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Capacitive deionization performance of bi-tortuous activated carbon electrodes coated with asymmetrically charged polyelectrolytes","abstract":"Capacitive deionization (CDI) is an electrochemical desalination technology in which porous carbon electrodes are polarized to reversibly store ions from a brackish water feed in electrical double layers in the electrodes. CDI is an attractive alternative to commonly used brackish water desalination technologies like reverse osmosis and thermal distillation due to its low energy consumption and potential for energy recovery. Electrode morphology and characteristics impact the desalination performance of CDI. Few of the CDI performance metrics like equivalent circuit resistance and charge efficiency also greatly impact CDI operation and performance. Planar composite CDI electrodes exhibit poor energetic performance due the resistance associated with salt depletion and tortuous diffusion in the macroporous structure. In this work, we investigate the impact of bi-tortuosity on desalination performance by etching macroporous patterns along the length of activated carbon porous electrodes in a flow-by CDI architecture. Capacitive electrodes were also coated with thin asymmetrically charged polyelectrolytes to improve ion-selectivity while maintaining the bi-tortuous (BT) macroporous channels. Under constant current operation, the equivalent circuit resistance in CDI cells operating with bi-tortuous electrodes was approximately 2.2 times less than a control cell with unpatterned electrodes, leading to significant increases in working capacitance (20 – 22 to 27 – 28 F g-1), round-trip efficiency (52 – 71 to 71 - 80%), charge efficiency (33 – 59 to 35 – 67%), which led to improvements in salt adsorption capacity, rate, and most importantly, the thermodynamic efficiency of salt separation (1.0 - 2.0 to 2.2 – 4.1 %). These findings demonstrate that the use of bi-tortuous electrodes is a novel approach of reducing impedance to ionic flux in CDI. In summary, the heightened performance of fb-CDI with coated BT electrodes elucidates that both ESR and 𝜂𝐶𝐸 are key indicators of energy efficiency desalination.","abstract_html":"Capacitive deionization (CDI) is an electrochemical desalination technology in which porous carbon electrodes are polarized to reversibly store ions from a brackish water feed in electrical double layers in the electrodes. CDI is an attractive alternative to commonly used brackish water desalination technologies like reverse osmosis and thermal distillation due to its low energy consumption and potential for energy recovery. Electrode morphology and characteristics impact the desalination performance of CDI. Few of the CDI performance metrics like equivalent circuit resistance and charge efficiency also greatly impact CDI operation and performance. Planar composite CDI electrodes exhibit poor energetic performance due the resistance associated with salt depletion and tortuous diffusion in the macroporous structure. In this work, we investigate the impact of bi-tortuosity on desalination performance by etching macroporous patterns along the length of activated carbon porous electrodes in a flow-by CDI architecture. Capacitive electrodes were also coated with thin asymmetrically charged polyelectrolytes to improve ion-selectivity while maintaining the bi-tortuous (BT) macroporous channels. Under constant current operation, the equivalent circuit resistance in CDI cells operating with bi-tortuous electrodes was approximately 2.2 times less than a control cell with unpatterned electrodes, leading to significant increases in working capacitance (20 – 22 to 27 – 28 F g-1), round-trip efficiency (52 – 71 to 71 - 80%), charge efficiency (33 – 59 to 35 – 67%), which led to improvements in salt adsorption capacity, rate, and most importantly, the thermodynamic efficiency of salt separation (1.0 - 2.0 to 2.2 – 4.1 %). These findings demonstrate that the use of bi-tortuous electrodes is a novel approach of reducing impedance to ionic flux in CDI. In summary, the heightened performance of fb-CDI with coated BT electrodes elucidates that both ESR and 𝜂𝐶𝐸 are key indicators of energy efficiency desalination.","abstract_has_math":false,"creators":["Bhat, Akash Pundalik"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Environ Engr in Civil Engr","degree_department":null,"school":null,"contributors":["Cusick, Roland D."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2019,"date_issued":"2019-08-23T19:58:04Z","date_published":"2019-08-23T19:58:04Z","updated_at":"2026-07-22T22:24:42Z","subjects":["Capacitive deionization","bi-tortuous electrodes","polyelectrolyte coating"],"languages":["en"],"rights":["Copyright 2019 Akash Bhat"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/104883","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Cusick, Roland D."]},{"key":"dc:creator","label":"Author","values":["Bhat, Akash Pundalik"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2019-08-23T19:58:04Z","2019-04-23","2019-05"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Environ Engr in Civil Engr"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Capacitive deionization","bi-tortuous electrodes","polyelectrolyte coating"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2019 Akash Bhat"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/104883"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Capacitive deionization (CDI) is an electrochemical desalination technology in which porous carbon electrodes are polarized to reversibly store ions from a brackish water feed in electrical double layers in the electrodes. CDI is an attractive alternative to commonly used brackish water desalination technologies like reverse osmosis and thermal distillation due to its low energy consumption and potential for energy recovery. Electrode morphology and characteristics impact the desalination performance of CDI. Few of the CDI performance metrics like equivalent circuit resistance and charge efficiency also greatly impact CDI operation and performance. Planar composite CDI electrodes exhibit poor energetic performance due the resistance associated with salt depletion and tortuous diffusion in the macroporous structure. In this work, we investigate the impact of bi-tortuosity on desalination performance by etching macroporous patterns along the length of activated carbon porous electrodes in a flow-by CDI architecture. Capacitive electrodes were also coated with thin asymmetrically charged polyelectrolytes to improve ion-selectivity while maintaining the bi-tortuous (BT) macroporous channels. Under constant current operation, the equivalent circuit resistance in CDI cells operating with bi-tortuous electrodes was approximately 2.2 times less than a control cell with unpatterned electrodes, leading to significant increases in working capacitance (20 – 22 to 27 – 28 F g-1), round-trip efficiency (52 – 71 to 71 - 80%), charge efficiency (33 – 59 to 35 – 67%), which led to improvements in salt adsorption capacity, rate, and most importantly, the thermodynamic efficiency of salt separation (1.0 - 2.0 to 2.2 – 4.1 %). These findings demonstrate that the use of bi-tortuous electrodes is a novel approach of reducing impedance to ionic flux in CDI. In summary, the heightened performance of fb-CDI with coated BT electrodes elucidates that both ESR and 𝜂𝐶𝐸 are key indicators of energy efficiency desalination.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2019-08-22 without embargo terms","The student, Akash Bhat, accepted the attached license on 2019-04-19 at 13:06.","The student, Akash Bhat, submitted this Thesis for approval on 2019-04-19 at 13:10.","This Thesis was approved for publication on 2019-04-23 at 09:21.","DSpace SAF Submission Ingestion Package generated from Vireo submission #13786 on 2019-08-22 at 14:45:04","Made available in DSpace on 2019-08-23T19:58:04Z (GMT). No. of bitstreams: 2 BHAT-THESIS-2019.pdf: 1453808 bytes, checksum: c299907ca571236582e52e0cb72312da (MD5) LICENSE.txt: 4207 bytes, checksum: fdaaeece358be906748e639202880a37 (MD5) Previous issue date: 2019-04-23"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Capacitive deionization performance of bi-tortuous activated carbon electrodes coated with asymmetrically charged polyelectrolytes"]}]}],"canonical_facts":{"dc:contributor":["Cusick, Roland D."],"dc:creator":["Bhat, Akash Pundalik"],"dc:date":["2019-08-23T19:58:04Z","2019-04-23","2019-05"],"dc:description":["Capacitive deionization (CDI) is an electrochemical desalination technology in which porous carbon electrodes are polarized to reversibly store ions from a brackish water feed in electrical double layers in the electrodes. CDI is an attractive alternative to commonly used brackish water desalination technologies like reverse osmosis and thermal distillation due to its low energy consumption and potential for energy recovery. Electrode morphology and characteristics impact the desalination performance of CDI. Few of the CDI performance metrics like equivalent circuit resistance and charge efficiency also greatly impact CDI operation and performance. Planar composite CDI electrodes exhibit poor energetic performance due the resistance associated with salt depletion and tortuous diffusion in the macroporous structure. In this work, we investigate the impact of bi-tortuosity on desalination performance by etching macroporous patterns along the length of activated carbon porous electrodes in a flow-by CDI architecture. Capacitive electrodes were also coated with thin asymmetrically charged polyelectrolytes to improve ion-selectivity while maintaining the bi-tortuous (BT) macroporous channels. Under constant current operation, the equivalent circuit resistance in CDI cells operating with bi-tortuous electrodes was approximately 2.2 times less than a control cell with unpatterned electrodes, leading to significant increases in working capacitance (20 – 22 to 27 – 28 F g-1), round-trip efficiency (52 – 71 to 71 - 80%), charge efficiency (33 – 59 to 35 – 67%), which led to improvements in salt adsorption capacity, rate, and most importantly, the thermodynamic efficiency of salt separation (1.0 - 2.0 to 2.2 – 4.1 %). These findings demonstrate that the use of bi-tortuous electrodes is a novel approach of reducing impedance to ionic flux in CDI. In summary, the heightened performance of fb-CDI with coated BT electrodes elucidates that both ESR and 𝜂𝐶𝐸 are key indicators of energy efficiency desalination.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2019-08-22 without embargo terms","The student, Akash Bhat, accepted the attached license on 2019-04-19 at 13:06.","The student, Akash Bhat, submitted this Thesis for approval on 2019-04-19 at 13:10.","This Thesis was approved for publication on 2019-04-23 at 09:21.","DSpace SAF Submission Ingestion Package generated from Vireo submission #13786 on 2019-08-22 at 14:45:04","Made available in DSpace on 2019-08-23T19:58:04Z (GMT). No. of bitstreams: 2 BHAT-THESIS-2019.pdf: 1453808 bytes, checksum: c299907ca571236582e52e0cb72312da (MD5) LICENSE.txt: 4207 bytes, checksum: fdaaeece358be906748e639202880a37 (MD5) Previous issue date: 2019-04-23"],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/104883"],"dc:language":["en"],"dc:rights":["Copyright 2019 Akash Bhat"],"dc:subject":["Capacitive deionization","bi-tortuous electrodes","polyelectrolyte coating"],"dc:title":["Capacitive deionization performance of bi-tortuous activated carbon electrodes coated with asymmetrically charged polyelectrolytes"],"dc:type":["text"],"thesis:degree_discipline":["Environ Engr in Civil Engr"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["M.S."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:24:42Z"}