Plazmonski Au/TiO2 fotokatalizatorji za oksidativno razgradnjo bisfenola A v vodni raztopini

Erhatič, Klemen (author), Plazl, Igor (mentor)

Zaradi rasti populacije, strogih zdravstvenih predpisov in ekonomskega razvoja se je potreba po vodi boljše kakovosti v zadnjih letih povečala. Tako je globalni cilj postalo odstranjevanje oziroma razgrajevanje nevarnih organskih onesnažil iz odpadnih vod. Med temi onesnažili so tudi bisfenoli, med katere med drugim spadajo bisfenol A (BPA), bisfenol F (BPF), bisfenol AF (BPAF) in bisfenol S (BPS). Ti bisfenoli spadajo med hormonske motilce in so škodljivi že v nizkih koncentracijah, zato jih je potrebno odstraniti iz odpadnih vod. Za odstranjevanje le-teh so najbolj primerni napredni oksidacijski procesi (AOPs), ki se jih zato zadnja leta intenzivno preučuje. Eden izmed naprednih oksidacijski procesov je tudi heterogena fotokatalitska oksidacija s katalizatorjem TiO2. Cilj magistrske naloge je bila sinteza plazmonskih fotokatalizatorjev na osnovi TiO2, na katerega smo želeli nanesti različne količine zlata, pripravljene katalizatorje pa uporabiti za fotokatalitsko odstranjevanje BPA v šaržnem reaktorju. Uporabili smo dve različni morfologiji TiO2 (nanodelci in nanopalčke). Pred uporabo za razgradnjo BPA smo katalizatorje preizkusili v reakcijah s tereftalno kislino (TA) in kumarinom (COUM), da smo preverili zmožnost tvorjenja OH radikalov. Učinkovitost fotokatalitske razgradnje smo ocenili s kemijskimi analiznimi metodami. S HPLC metodo smo preverjali koncentracijo BPA v vzorcih, vzetih med fotokatalitsko reakcijo, ter jih primerjali z začetno raztopino BPA. Dokazali, da se je BPA mineraliziral, ne pa vezal na površino katalizatorja. Rezultati analiz so pokazali, da z nanašanjem Au na katalizator ne vplivamo na njegovo morfologijo in se dejanske količine nanosa ujemajo z željenimi nanosi Au. Ko smo opravili razgradnjo BPA z vsemi katalizatorji, smo pri vsaki morfologiji izbrali katalizator, ki je bil najbolj učinkovit in z njim poskusili razgraditi BPF, BPAF in BPS, saj so to analogi BPA, ki se pogosto uporabljajo kot zamenjava za BPA. Katalizatorja, ki sta se najbolje izkazala, sta bila TNP + 2 % Au in TNR + 1 % Au. Razgradnja BPF je bila podobna kot pri BPA. BPAF in BPS sta izkazala višjo odpornost na reakcije z reaktivnimi kisikovimi specijami. Pri obeh katalizatorjih je bila razgradnja skoraj zanemarljiva. Razlog za odpornost je verjetno sama struktura molekul, zelo močna B – F vez v BF3 pri BPAF in dvojnih vezeh med O in S v sulfonilni skupini pri BPS molekuli. Iz dobljenih rezultatov lahko sklepamo, da je zamenjava BPA v industrijskih procesih z njegovimi analogi, kot sta BPAF in BPS, vprašljiva.

• Language: English
• Keywords: heterogena fotokataliza, AOP, Au nanodelci, TiO2, bisfenoli
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2020
• PID: 20.500.12556/RUL-119418
• COBISS.SI-ID: 29405443
• Publication date in RUL: 08.09.2020

Secondary language

• Language: Slovenian
• Title: Plasmonic Au/TiO2 photocatalysts for oxidative degradation of bisphenol A in aqueous solution

Abstract

Due to population growth, strict health regulations, and economic development, the need for better quality water has increased in recent years. Thus, the removal or decomposition of hazardous organic materials and pollutants from wastewater has become a global goal. These contaminants include bisphenols, including bisphenol A (BPA), bisphenol F (BPF), bisphenol AF (BPAF), and bisphenol S (BPS). These bisphenols are hormone disruptors and are harmful even in low concentrations, so they must be removed from wastewater. Advanced oxidation processes (AOPs) are the most suitable for their removal and have therefore been intensively studied in recent years. One of the advanced oxidation processes is also heterogeneous photocatalysis with a TiO2 catalyst. The aim of the master's thesis was the synthesis of plasmonic photocatalysts based on TiO2, to which we wanted to apply different loadings of gold, and the prepared catalysts were later used for photocatalytic removal of BPA in a batch slurry reactor. We also used two different morphologies of TiO2 (nanoparticles and nanorods). Before the catalysts were used to degrade BPA, they were tested in reactions with terephthalic acid (TA) and coumarin (COUM) to test the ability to form OH radicals. The efficiency of photocatalytic degradation was then evaluated by chemical analytical methods. The concentration of BPA in the samples taken during the photocatalytic reaction was checked by means of HPLC analysis and compared with the initial BPA solution. We demonstrated that BPA was mineralized rather than accumulated on the catalyst surface. The results of analyses showed that the application of Au to the catalyst does not affect its morphology and the actual loading amounts of Au correspond to the nominal values. After performing BPA degradation with all catalysts, we selected the catalyst with highest activity for each morphology and tried to degrade BPF, BPAF, and BPS over these solids, as these compounds are BPA analogs that are often used as a replacement for BPA. The best catalysts were TNP + 2% Au and TNR + 1% Au. The degradation of BPF was similar to that of BPA, because they are structurally similar. BPAF and BPS showed higher resistance to reactions with reactive oxygen species. For both catalysts, the degradation was almost negligible. The reason for the resistance is probably the structure of the molecules itself, the very strong B - F bond in BF3 moiety of BPAF and the double bonds between O and S in the sulfonyl group in the BPS.

• Keywords: heterogeneous photocatalysis, AOPs, Au nanoparticles, TiO2, bisphenols