Application of Titanium Dioxide (TiO₂)-Embedded Buoyant Photocatalyst Balls Using Expanded Polystyrene.

A new immobilization technique of nanoscale TiO₂ powders to expanded polystryrene (EPS) balls with temperature-controlled melting method was validated for mass production, and the photocatalytic activity of TiO₂ powder-embedded EPS (TiEPS) balls using methylene blue (MB) solution with different concentrations under ultraviolet irradiation and under the natural solar light irradiation. Whereas MB molecules were weakly adsorbed onto the surface of both TiO₂ powders and supporting polymers without any specific interactions, the photocatalytic efficiency of TiEPS balls with UV ( =0.016~0.043 min) was greater through coupled reaction processes (adsorption, photolysis, and photocatalysis). After 5-min sonication, more TiO₂ powders on the TiEPS balls can be involved into the both adsorption and photocatalytic reactions of MB, and can increase the MB removal efficiencies. TiEPS balls can be reused for several consecutive runs without any significant decrease in photocatalytic activity until the recalcitrant contaminants were completely coated on the surface of TiEPS balls and loss of TiO₂ powders embedded on the surface of TiEPS balls was significant. Based on the aforementioned results, self-floating TiEPS balls manufactured from this simple and cost-effective melting method can be used to remove the organic contaminants and to inhibit the excessive growth of harmful algae in the stagnant water body.