Photocatalytic materials for water treatment and antimicrobial applications
Date
2024-07-09
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Abstract
Kasvav rahvastikutihedus on põhjustanud nii saasteainete kui võimalike patogeensete bakterite kogunemise keskkonda. Ühe lahendusena on soovimatute saasteainete ja patogeensete bakterite lagundamiseks pakutud välja fotokatalüüs – protsess, mille käigus keemilised reaktsioonid aktiveeritakse fotokatalüsaatori pinnal valguse toimel. Reaktsioonide käigus fotokatalüsaator ise ei lagune ning reeglina on fotokatalüsaator ka inertne ja kahjutu keemiline ühend.
Käesolevas doktoritöös keskenduti titaandioksiidil (TiO₂) ja tsinkoksiidil (ZnO) põhinevate fotokatalüütiliste materjalide väljatöötamisele vee puhastamiseks ja antimikroobsete katete valmistamiseks. Töö esimeses osa keskenduti vee puhastamiseks kasutatavatele fotokatalüütilistele osakestele. Selleks sünteesiti magnetiliselt fotokatalüsaatorid, kombineerides TiO₂-P25 magnetise vaskferriidiga. Fotokatalüsaator lagundas herbitsiidi 2,4-D ning fotokatalüsaatorit oli võimalik veest kinni püüda ning taaskasutada.
Lisaks uuriti akrüülmaatriksis olevaid ZnO ja ZnO/Ag nano- või mikrosuuruses osakestel põhinevaid fotokatalüütilisi antimikroobseid pinnakatteid vineeril ja roostevabal terasel. Seesugused pinnakatted näitasid laboritingimustes paljutõotavat fotokatalüütilist ja mikroobide vastast aktiivsust. Lisaks säilitasid pinnakatted oma efektiivsuse pärast simuleeritud kulumist.
Viimasena uuriti kaubanduslikke TiO₂-põhiseid fotokatalüütilisi aknaklaase BIOCLEAN® ja SaniTise™. Nendest viimasel on väidete järgi nii fotokatalüütiline kui antibakteriaalne aktiivsus. Uuringus leiti, et SaniTise™ pind oli fotokatalüütilisem ja antibakteriaalsem kui BIOCLEAN® oma.
Käesolev doktoritöö rakendab mitmekülgset lähenemist fotokatalüütiliste materjalide väljatöötamiseks ja nende komplekseks iseloomustamiseks suurendades arusaamist materjali koostisest ja võimalikust kasutamisest. Jätkuvad uuringud selles valdkonnas võivad sillutada teed keskkonnasõbralikele fotokatalüütilistele süsteemidele väljatöötamiseks vee puhastamiseks ja antimikroobsetele kateteks.
Urbanization have increased levels of harmful pollutants and antibody-resistant microbes in our environment. Now photocatalysis has emerged as an alternative and promising sustainable solution for water cleaning and disinfection. During the reactions photocatalyst itself does not decompose and is an inert nontoxic compound. This thesis focuses on developing photocatalytic materials based on titanium dioxide (TiO₂) and zinc oxide (ZnO) for water purification and antimicrobial coatings. Firstly, the focus was on the photocatalytic particles used for water purification. For this purpose, magnetically recoverable photocatalysts were synthesized by combining TiO₂–P25 with magnetic copper ferrite. The photocatalyst effectively degraded a commonly used herbicide (2,4-D), and was successfully recovered and reused. After that, the focus shifted towards the development of photocatalytic antimicrobial coating based on ZnO and Ag-doped ZnO. Nano- or microsized particles of ZnO and ZnO/Ag were embedded to an acrylic matrix and applied onto plywood or stainless steel. These coatings exhibited promising photocatalytic activity and photo-induced antibacterial activity in laboratory conditions. Furthermore, ZnO-based acrylic matrix coatings preserved their photocatalytic and antibacterial efficiency after simulated wear and tear. Lastly, the commercial photocatalytic window glass based on TiO₂ coatings, BIOCLEAN® and SaniTise™, were investigated. It has been claimed that SaniTise™ has also antimicrobial functionalities. Analyses showed that SaniTise™ demonstrated higher photocatalytic and antibacterial activity than BIOCLEAN®. Overall, the approach used in this thesis was designed to encompass different aspects of the development and application of photocatalytic materials, enhancing the understanding of material composition and possible use. Continued research in this field can pave the way for eco-friendly photocatalytic systems for water treatment and antimicrobial coatings.
Urbanization have increased levels of harmful pollutants and antibody-resistant microbes in our environment. Now photocatalysis has emerged as an alternative and promising sustainable solution for water cleaning and disinfection. During the reactions photocatalyst itself does not decompose and is an inert nontoxic compound. This thesis focuses on developing photocatalytic materials based on titanium dioxide (TiO₂) and zinc oxide (ZnO) for water purification and antimicrobial coatings. Firstly, the focus was on the photocatalytic particles used for water purification. For this purpose, magnetically recoverable photocatalysts were synthesized by combining TiO₂–P25 with magnetic copper ferrite. The photocatalyst effectively degraded a commonly used herbicide (2,4-D), and was successfully recovered and reused. After that, the focus shifted towards the development of photocatalytic antimicrobial coating based on ZnO and Ag-doped ZnO. Nano- or microsized particles of ZnO and ZnO/Ag were embedded to an acrylic matrix and applied onto plywood or stainless steel. These coatings exhibited promising photocatalytic activity and photo-induced antibacterial activity in laboratory conditions. Furthermore, ZnO-based acrylic matrix coatings preserved their photocatalytic and antibacterial efficiency after simulated wear and tear. Lastly, the commercial photocatalytic window glass based on TiO₂ coatings, BIOCLEAN® and SaniTise™, were investigated. It has been claimed that SaniTise™ has also antimicrobial functionalities. Analyses showed that SaniTise™ demonstrated higher photocatalytic and antibacterial activity than BIOCLEAN®. Overall, the approach used in this thesis was designed to encompass different aspects of the development and application of photocatalytic materials, enhancing the understanding of material composition and possible use. Continued research in this field can pave the way for eco-friendly photocatalytic systems for water treatment and antimicrobial coatings.
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