التحفيز الضوئي لاختزال أيون الكروم السداسي بوساطة ثاني أوكسيد التيتانيوم بالوسط المائي

الملخص EN

The work include the study of photocatalytic reduction of ion Cr (VI)that is consider a main source of environmental pollution were investigated using titanium dioxide (Rutile or Anatase) in aqueous solution.

Results show that this harmfull (toxic) ion is converted with different speed to non toxic ion Cr (III).The speed of the photoconversion processes depends on many factors such as, solution acidity, temp., initial ion concentration, TiO2 load and type (anatase or rutile), the presence of dissolved oxggen gas and finally the insensity of incident light kinetic.

studies show that the rate of reduction of Cr6+ is 1.5  10-3 mM/min.

It was found that the rate of the reactions are first order reactions were and the specific rate constant and adsorption constant were deduced adopting the Langmuir - Hinshelwood (L-H) relation for the catalytic- heterogeneous reaction.

The values of the specific rate constant (K) for the photoreduction processes of ion is found in consistent with that calculated from the logarithmatic plots of the ion concentration left after photoreactions versns reaction times.

From L-H equation, the adsorption constants obtained for Cr6+ 0.043 mM-1.The values of the apparent quantum yields was also deduced for Cr6 +equal to 0.26.

The specrophometric, ion- chromatography, pH measurements and conductivity techniques were used in the present work in order to elucidate the types of the products and the photo reaction mechanisms.