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Identifier

000364248

Title

Χημική σύνθεση νανοκόνεων οξειδίου του ψευδαργύρου από υδατικά διαλύματα και μελέτη της φωτοκαταλυτικής τους απόδοσης για τη διάσπαση υδατικού διαλύματος του μπλε του μεθυλενίου

Alternative Title

Chemical synthesis of zinc oxide powder samples from aqueous solutions and study of their photocatalytic activity for the degradation of methylene blue

Author

Ηλιάδης, Ιωάννης Αντ.

Thesis advisor

Δημάδης Κωνσταντίνος

Abstract

This MSc dissertation studies the synthesis of ZnO powder samples, via the sol–gel and citrate gel methods using ZnAc and Zn (NO₃)₂, as precursors, but also via Aqueous Chemical Growth (ACG) a simple, environmentally‐friendly chemical method at low temperatures (95 ^οC). The synthetic as well as commercial ZnO samples are examined regarding their structural and morphological characteristics via XRD, SEM and RAMAN. Concerning the ZnO samples prepared by the sol‐gel and citrate gel methods at 400‐900 ^οC, ACG samples at 95 ^οC present completely different morphology but also high crystallinity. Synthetic samples, correspond to the hexagonal P6(3)mc ZnO wurtzite structure, while admixtures or other phases of ZnO are not present. Synthetic and commercial ZnO powders are also examined for their photocatalytic activity, which leads to discoloration and degradation of Methylene Blue (MB) aqueous dye solutions. This examination has to do with the structural factors of samples as crystallinity and morphology but also with the effect of experimental conditions as the power and the wavelength of the radiation that enters in the volume of the solution. Therefore, at the process of the photocatalytic experiments a batch reactor, two lamps TQ 150 and TQ 150 Z1 and three wrappings (Quartz, Duran 50 and M380) are used. The results show that photocatalytic process indeed occurs by the activation of the catalyst (even in small concentration 0,2 gr/L or 200 ppm) from the radiation and further oxidation of MB aqueous dye solution. In many cases, the attribution of degradation of MB aqueous dye solution using synthetic ZnO powders is close to this using commercial ZnO powder catalyst. Finally, measurements of total organic carbon (TOC) are performed. From this procedure the effectiveness of photocatalytic activity (using ZnO as catalyst) in the reduction of organic matter of MB aqueous dye solution is estimated. Results show that the reduction of organic matter follows in general the discoloration of dye solution but needs more irradiation time, i.e, at least 10hr.

Language

Greek

Subject

Batch Reactor

Photocatalysis

Total Organic Carbon

ZnO

Αντιδραστήρας Αδιάλειπτης Ροής

Ολικός Οργανικός Άνθρακας

Φωτοκατάλυση

Issue date

2010-01-26