Photocatalytic mineralisation of methylene blue using buoyant TiO2-coated polystyrene beads

The photocatalysed mineralisation of methylene blue has been carried out using TiO2 coated onto naturally buoyant polystyrene beads. Titanium dioxide is coated onto polystyrene using a thermal treatment procedure. The coated beads show high mechanical stability as well as impressive photocatalytic activity. Thermogravimetric analysis of the beads, post-treatment, indicates that there is no destructive degradation of the Polystyrene support by the photocatalytic process. The catalyst activity remains appreciably high for up to 10 successive runs. For the buoyant particles, suspension is only possible for situations where pulsatile mixing is applied. Reaction rates in this system are found to increase with increase both in the catalyst loading and the pulsing conditions. (C) 2000 Elsevier Science S.A. All rights reserved.