Abstract :
A commercial detergent whose major components are an anionic surfactant and a fluorescent whitening agent can be
photodegraded in aqueous TiO2 dispersions under irradiation with concentrated sunlight in the presence of air. The
degradation process followed apparent first-order kinetics in terms of the total sunlight energy impinging on the photoreactive
system. The effects of (a) TiO2 loading, (b) circulation flow rate, and (c) pH of the reactant solution on the
kinetics of decomposition of the detergent were examined. Under the prevailing conditions, the optimal operational
parameters for this detergent were, respectively: TiO2 loading, 6 gl 1; circulation flow rate, 4.9 lmin 1; and pH, 4.9.
The rate of increase of the surface tension was greater than the rate of decrease of the concentration of the detergent.
This study adds to our knowledge base in the effective use of sunlight irradiation to detoxify wastewaters containing
undesirable detergents.
2004 Elsevier Ltd. All rights reserved.
