Banca de DEFESA: ISLANNY LARISSA OURIQUES BRASILEIRO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : ISLANNY LARISSA OURIQUES BRASILEIRO
DATE: 16/12/2022
TIME: 09:45
LOCAL: Online via Google Meet
TITLE:

DEVELOPMENT OF ZnO/g-C₃N₄ AND ZnFe₂O₄/g-C₃N₄ HETEROJUNCTIONS FOR PHOTODEGRADATION OF EMERGING ORGANIC CONTAMINANTS

KEY WORDS:

ZnO/g-C₃N₄ heterojunction, ZnFe₂O₄/g-C₃N₄ heterojunction, Cefazolin, Reactive Black 5, Heterogeneous Photocatalysis, Scheme Z, Experimental design, Kinetic study.  

PAGES: 168
BIG AREA: Engenharias
AREA: Engenharia Química
SUBÁREA: Processos Industriais de Engenharia Química
SPECIALTY: Processos Inorgânicos
SUMMARY:

In recent years there has been growing concern about the contamination of water by emerging contaminants - substances that are not completely degraded by conventional processes of water and wastewater treatments and are not biodegradable. For this reason, several techniques have been developed to efficiently treat such compounds. In this work, different heterojunctions of ZnO/g-C₃N₄ and ZnFe₂O₄/g-C₃N₄ in different mass proportions of g-C₃N₄ (10, 50, and 80 %) were synthesized through a simple method of mixing, sonication and heat treatment. The influence of the amount of g-C₃N₄ in the heterojunctions as well as the influence of the type of zinc-based catalyst on the structural, morphological, optical, and photocatalytic properties of the materials were investigated. The XRD, FTIR, and SEM/EDS results confirmed the achievement of the desired heterojunctions. The incorporation of g-C₃N₄ was relevant in modifying the textural and optical properties of the heterojunctions produced. The 50-Zn/gCN heterojunction showed better photocatalytic degradation of the antibiotic cefazolin (78 %) and the dye RB5 (95 %) in 120 min of the experiment, when compared with the pure materials and with the other heterojunctions. In addition, it exhibited faster reaction kinetics and good photostability. The best photocatalytic performance presented by this material can be attributed to the real synergistic effect between ZnO and g-C₃N₄, which promoted relevant interaction in a possible mechanism of Z scheme type, as verified in the PL analysis. The results of the experimental design showed that the catalyst concentration and the pH are the variables that most influence the cefazolin photodegradation, whereas for RB5, all the evaluated variables were significant for 95% confidence. 50-Zn/gCN exhibited 100% degradation for both contaminants evaluated in 90 min of reaction for cefazolin and in 10 min for RB5, under the following conditions: catalyst concentration 0.5 g L^-1, contaminant concentration 5 mg L^-1 and pH 2.5. Adsorption played a key role in the photodegradation of RB5. However, the degradation of the dye (adsorbed and remaining in the solution) and the regeneration of the catalyst surface were due to photocatalysis. The Z-scheme mechanisms for the photocatalytic reactions of cefazolin and RB5 have been adequately proposed, in which the photogenerated holes in the valence band of ZnO and the electrons in the conduction band of g-C₃N₄ were the main degradation pathways of cefazolin and RB5, respectively. The evaluated heterojunction showed good photostability for both contaminants. Finally, the promising character of 50-Zn/gCN synthesized for application in photocatalytic reactions mediated by sunlight for the degradation of contaminants of different classes, as well as the possibility of its use as an efficient alternative to minimize water pollution caused by overuse of medication during the COVID-19 pandemic. 

COMMITTEE MEMBERS:
Presidente - 2929066 - ANDRE LUIS LOPES MORIYAMA
Externa ao Programa - 1271737 - CAMILA PACELLY BRANDÃO DE ARAÚJO - nullExterna à Instituição - MAITÊ MEDEIROS DE SANTANA E SILVA - UFRN
Externa à Instituição - REGINA DE FÁTIMA PERALTA MUNIZ MOREIRA - UFSC
Externa à Instituição - VIVIAN STUMPF MADEIRA - UFPB