KINETIC STUDIES OF PHOTOCATALYTIC DECOMPOSITION OF ERIOCHROME BLACK T IN BUFFER SOLUTIONS AT VARIUOS pHs UNDER HIGH PRESSURE MERCURY LAMP IRRADIATION

Photocatalytic decomposition of an azo dye, Eriochrome Black T using anatase titanium dioxide (99.9%) at buffer pHs of 7, 8, 10 and 12 in aqueous solution has been carried out. The effect of the various operating agents such as initial concentration of dye, catalyst amount and reaction time on photocatalytic decomposition has been investigated in a photoreactor cell containing 400W high pressure mercury lamp as irradiation source to derive the optimum conditions in each pH. Spectrophotometric method revealed that the compound almost completely degraded. The photodegradation of compound obeys a pseudo-first-order kinetics based on Langmuir-Hinshelwood model at all considered pHs. The observed rate constants(k(obs)) of photocatalytic degradation were found to be 5.50x10(-3), 7.40x10(-3), 5.10x10(-3) and 5.7 x 10(-3) for buffer pHs of 7, 8, 10 and 12 respectively. Furthermore, the Langmuir-Hinshelwood rate constants, k(r) and adsorption constants, K(A) for the titled compound at various buffer pHs are reported.