Tez özetleri Astronomi ve Uzay Bilimleri Anabilim Dalı

Adsorption and Photocatalytic Degradation of Organic Compounds on Titanium-Dioxide

Adsorption and/or photo catalytic degradation of some organic compounds such as bioflavonoids and surfactants have been studied on TiO2 nanoparticles by means of spectrophotometric method.

The solutions of cetyl piridinium chloride (CPC) which is a cationic surfactant were contacted with TiO2 under dark and illuminated conditions to elucidate the effect of adsorption or photocatalitic degradation. Experiments conducted depending on time, TiO2 dosage and initial concentration of CPC show that adsorption phenomena affect on reaction mechanisms rather than photo catalitic degradation. Sequential desorption studies also confirmed that adsorption takes place on TiO2 nanoparticles. Amount of adsorbed surfactant increased with solution /solid ratio whereas an inverse effect was observed on distribution coefficients. A two-step adsorption isotherm was obtained which is a typical shape for surfactant adsorption.

The percentage of photo catalytic degradation of flavone attained upto 80% after illumination with sun light during 6 hours. Photo catalytic degradation was decreased to around 40% in the presence of tetraethyl ammonium-hydroxide (TEAOH). No degradation was observed under dark conditions or during the night. However, photo degradation restarted when the system was exposured to the light again and flavon was completely decomposed.

Similar behavior was also observed for hesperidin solutions in the presence and in the absence of TEAOH under the same conditions. Desorption studies also showed that photo catalytic degradation is dominant mechanism for hesperidin consumption. Langmuir-Hinshelwood equation was successfully applied to the kinetic data obtained for flavon and hesperidin.

On the other hand, experimental results obtained from dark and illuminated solutions exhibited that the retention mechanism of rutin on TiO2 is adsorption. A sharp increase observed in the distribution coefficients until a solution/solid ratio of 0.1 l/g slows down after this value. Kinetic data for rutin adsorption are well described by McKay equation.

X-ray diffraction (XRD) and Furrier transform infrared (FTIR) spectra of TiO2 treated and untreated with the organic substances were compared for illuminated and dark conditions. The results are well consistent with experimental observations.

AYDIN Elif
Danışman : Prof.Dr. F. Serpil GÖKSEL

Anabilim Dalı : Kimya

Programı : Organik Kimya

Mezuniyet Yılı : 2008

Tez Savunma Jürisi : Prof.Dr.F.Serpil GÖKSEL(Danışman)

Prof.Dr.Cemil İBİŞ

Prof.Dr. Mustafa BULUT

Prof.Dr.Süleyman TANYOLAÇ

Prof.Dr.Ayşe YUSUFOĞLU