Photocatalytic Iodometry over Naked and Sensitized Zinc Oxide

Abstract

Photocatalytic oxidation of iodide ion in the aqueous suspension of zinc oxide
and its sensitization with riboflavin has been done . Irradiation of reaction mixture
was done by used each of visible , and ultraviolet radiation. The concentration of
iodine formed was determined by spectrophotometric method . According to this
method the amount of product formed was finding by a suitable calibration curve and
measuring the absorbance at ( 350 nm) . The reaction was done at three different
temperatures 293,298 and 303 K. Effect of temperature on the rate of reaction was
used in calculation of activation energy which was about (24 kJ. mol-1 ). Langmuir-
Hinshilwood(LH) kinetic model was applied for the reaction as it first order in its
kinetics which gives reaction rate constant of (1.4*10-6 sec-1 ) and equilibrium
adsorption constant of (2.5 * 104 l.mol-1).The results showed that sensitized zinc oxide
was more active that naked form . Also used ultraviolet light was more efficient then
visible light . The efficiency of reaction increased with elevation in the temperature
of reaction .Also the basisity of solution was increased with the development of
reaction