Composite membranes of sulfonated poly (Ether ether ketone) with active carbon: Composite preparation and investigation of their properties for potential application for co2 electrochemical reduction

Authors of this work acknowledge funding from European Union`s Horizon 2020 Research and Innovation Program project under grant agreement No 768789.In this study, synthesis of sulfonated poly(ether ether ketone) (SPEEK) was performed using sulfonation method with concentrated sulfuric acid. Polymer with three degrees of sulfonation was obtained: 0.87; 0.82 and 0.74. Composite membranes were synthesized with an activated carbon. Ultrasonication method was used in order to achieve homogeneity of distribution of the additive in polymer solution and then in polymer membranes. Membranes with various content of the additive were made: 0; 0.15; 0.3; 0.5; 0.6; 0.8; 1.0; 2.0 and 3.0 %. Swelling degree, water uptake, proton conductivity, isoelectric point, thermal properties and surface morphology of the membranes were analyzed. Proton conductivity was determined using impedance analysis with two electrode system and through-plane configuration. Two methods were used: differential and single membrane method. Differential method is proposed to have significant advantage as it reduces contact resistance, which otherwise is difficult to control and evaluate. Surface zeta potential of membrane surface was investigated, and membranes have shown variation of the potential. Isoelectric point was determined for the membranes with DS 0.82 and carbon content 0 % and 0.5 %, and it was found to be at pH 4. Water uptake and swelling degree of the membranes was studied, and active carbon content was found to not have major influence on those properties, but higher content of sulfonic groups leads to increased water uptake and swelling degree. Thermogravimetric analysis showed slightly better thermal properties of membranes with the additive, compared to the blank membranes, which can be related to differences in the water uptake. Surface of the membrane was investigated using scanning electron microscopy, and no considerable defects were observed.Horizon 2020 No 768789; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

Promocijas darbs

Elektroniskā versija nesatur pielikumusŠajā promocijas darbā tika izstrādātas jaunas analītiskās metodes, izmantojot nanoplūsmas šķidrumu hromatogrāfiju (nano-LC) un Orbitrap masspektrometriju, lai noteiktu dažādus ķīmiskos piesārņotājus pārtikā un vidē. Tika veikts literatūras apskats par jaunākajiem nano-LC metožu pielietojumiem pārtikas nekaitīguma un vides analīžu jomā, uzsverot analizējamo savienojumu, matricu un analītisko metodoloģiju daudzveidību. Tika izstrādātas kvantitatīvas analītiskās metodes mikotoksīnu, pirolizidīna alkaloīdu, farmaceitisko savienojumu, populācijas veselības stāvokļa biomarķieru un perfluorētu savienojumu noteikšanai. Tika novērtētas dažādas nano-LC instrumentālās konfigurācijas, tostarp šķīdinātāja pievienošana pēc kolonnas. Ir izmantotas dažādas paraugu sagatavošanas pieejas, tostarp cietfāzes ekstrakcija, ātra, viegla, lēta, efektīva, izturīga un droša (QuEChERS) ekstrakcija un dilute-and-shoot pieeja. Tika izstrādāta mērķa jonu skrīninga metode, izmantojot selektīvus fragmentu jonus, kas ir specifiski pirolizidīna alkaloīdiem sadursmju izraisītas disociācijas apstākļos. Uzlabotā polāru savienojumu izdalīšana ar apgrieztās fazes nano-LC kolonnu ir demonstrēta biomarķieru un farmaceitisko savienojumu analīzē, paraugam pievienojot tetrabutilamonija bromīdu kā jonu pāra reaģentu. Izstrādātās nano-LC metodes tika pielietotas mikotoksīnu, pirolizidīna alkaloīdu un perfluorētu savienojumu noteikšanai pārtikas produktos no Latvijas veikaliem, kā arī tika pētīta farmaceitisko vielu un biomarķieru sastopamība notekūdeņos no dažādām Latvijas pilsētām. NANOPLŪSMAS ŠĶIDRUMA HROMATOGRĀFIJA, ORBITRAP MASSPEKTROMETRIJA, ĶĪMISKIE PIESĀRŅOTĀJI, NOTEKŪDEŅU EPIDEMIOLOĢIJA, MĒRĶA JONU SKRĪNINGS.In this doctoral thesis, novel analytical methods employing nanoflow liquid chromatography (nano-LC) and Orbitrap mass spectrometry were developed to determine various chemical contaminants in food and the environment. A literature review has been conducted on recent applications of nano-LC methods in the field of food safety and environmental analysis, highlighting the variety of analytes, matrices, and analytical methodologies. Quantitative analytical methods for determining mycotoxins, pyrrolizidine alkaloids, pharmaceuticals, population-health related biomarkers, and perfluorinated compounds were developed. Different nano-LC instrumental setups were evaluated, including post-column solvent addition. A variety of sample preparation techniques was applied, including solid-phase extraction, quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction, and dilute-and-shoot approach. A target ion screening approach was developed using selective fragment ions specific to pyrrolizidine alkaloids. Improved retention of ionic and highly polar compounds on reversed-phase nano-LC column has been demonstrated in the analysis of biomarkers and pharmaceuticals by the in-sample addition of tetrabutylammonium bromide as an ion pair reagent. The developed nano-LC methods were applied to study the occurrence of mycotoxins, pyrrolizidine alkaloids, and perfluorinated compounds in food from the Latvian market, and the occurrence of pharmaceuticals and biomarkers in wastewater from the wastewater treatment plants of different cities in Latvia was studied. NANOFLOW LIQUID CHROMATOGRAPHY, ORBITRAP MASS SPECTROMETRY, CHEMICAL CONTAMINANTS, WASTEWATER-BASED EPIDEMIOLOGY, TARGET ION SCREENIN

Determination of electrical conductivity of poly(ether ether ketone) membranes with different degree of sulfonation

Darbā ir veikta poli(ēter ētera ketona) sulfonēšana un ir iegūti paraugi ar dažādām sulfonēšanas pakāpēm, no kurām tika izgatavotas membrānas. Sulfonēšanas pakāpe tika noteikta ar titrēšanas metodi. Izmantojot impedances metodi, tika noteikta sulfonēta poli(ēter ētera ketona) membrānu elektrovadītspēja atkarībā no sulfonēšanas pakāpes. Membrānas tika analizētas ar rentgendifraktometrijas metodi un termogravimetrijas metodi.In this study poly(ether ether ketone) was sulfonated and membranes with different degree of sulfonation were made and membranes with different degree of sulfonation were obtained. Titration method was used to determine the degree of sulfonation. Impedance method was used to determine electrical conductivity of sulfonated poly(ether ether ketone) membranes depending on different degree of sulfonation. Membranes were also analysed with X-ray diffractometry and thermogravimetric analysis

Investigation of properties of SPEEK composite membranes for application in electrochemical CO2 converters

Šajā darbā ir veikta sulfonēta poli(ēter ēter ketona) (SPĒĒK) sintēze ar sulfonēšanas pakāpēm 0,87; 0,82; 0,74. No iegūtā SPĒĒK tika izgatavotas kompozītmembrānas ar atšķirīgu aktīvās ogles saturu: 0; 0,15; 0,3; 0,5; 0,6; 0,8; 1,0; 2,0; 3,0 %. Iegūto membrānu īpašības tika izpētītas ar dažādām metodēm. Kompozītmembrānām tika noteikta ūdens uzņemšana un uzbriešanas pakāpe. Impedances analīzi veica ar diferenciālo un vienas membrānas metodi. Tika pētītas arī virsmas dzeta potenciāla izmaiņas. Kompozītmembrānu termiskās īpašības analizēja ar termogravimetrisko metodi. Membrānu virsmas morfoloģiju pētīja ar skenējošās elektronu mikroskopijas metodi. SPĒĒK membrāna tika notestētas CO2 elektroķīmiskajā pārveidotājā.In this study sulfonated poly(ether ether ketone) (SPEEK) was synthesized with 0,87; 0,82; 0,74 degrees of sulfonation. SPEEK composite membranes with active carbon were prepared with 0; 0,15; 0,3; 0,5; 0,6; 0,8; 1,0; 2,0; 3,0 % carbon content. Some properties of the composite membranes were investigated. Water uptake and swelling degree were determined. Surface zeta potential of the membranes was investigated. Thermogravimetric analysis method was used to investigate thermal properties of the membranes. Surface morphology was studied using scanning electron microscopy. SPEEK membrane was tested in CO2 electrochemical reduction cell

Investigation of properties of SPEEK composite membranes for application in electrochemical CO2 converters

Šajā darbā ir veikta sulfonēta poli(ēter ēter ketona) (SPĒĒK) sintēze ar sulfonēšanas pakāpēm 0,87; 0,82; 0,74. No iegūtā SPĒĒK tika izgatavotas kompozītmembrānas ar atšķirīgu aktīvās ogles saturu: 0; 0,15; 0,3; 0,5; 0,6; 0,8; 1,0; 2,0; 3,0 %. Iegūto membrānu īpašības tika izpētītas ar dažādām metodēm. Kompozītmembrānām tika noteikta ūdens uzņemšana un uzbriešanas pakāpe. Impedances analīzi veica ar diferenciālo un vienas membrānas metodi. Tika pētītas arī virsmas dzeta potenciāla izmaiņas. Kompozītmembrānu termiskās īpašības analizēja ar termogravimetrisko metodi. Membrānu virsmas morfoloģiju pētīja ar skenējošās elektronu mikroskopijas metodi. SPĒĒK membrāna tika notestētas CO2 elektroķīmiskajā pārveidotājā.In this study sulfonated poly(ether ether ketone) (SPEEK) was synthesized with 0,87; 0,82; 0,74 degrees of sulfonation. SPEEK composite membranes with active carbon were prepared with 0; 0,15; 0,3; 0,5; 0,6; 0,8; 1,0; 2,0; 3,0 % carbon content. Some properties of the composite membranes were investigated. Water uptake and swelling degree were determined. Surface zeta potential of the membranes was investigated. Thermogravimetric analysis method was used to investigate thermal properties of the membranes. Surface morphology was studied using scanning electron microscopy. SPEEK membrane was tested in CO2 electrochemical reduction cell