Development of Titanium Dioxide (TiO2)-immobilized Buoyant Photocatalyst Balls Using Expanded Polystyrene (EPS)

: A new immobilization technique of nanoscale TiO 2 powder to expanded polystyrene (EPS) balls with temperature-controlled melting method was developed, and the photocatalytic activity of TiO 2 powder-embedded EPS balls were evaluated using methylene blue (MB) solution under ultraviolet irradiation ( λ = 254 nm). Based on the scanning electron microscope (SEM) images and associated energy-dispersive X-ray spectroscopy (EDX) analysis, the components of the intact EPS balls were mainly carbon and oxygen, whereas those of TiO 2 -immobilized EPS balls were carbon, oxygen, and titanium, indicating that relatively homogenous patches of TiO 2 and glycerin film were coated on the surface of EPS balls. Based on the comparison of degradation efficiencies of MB between intact and TiO 2 -immobilized EPS balls under UVC illumination, the degradation efficiencies of MB can be significantly improved using TiO 2 -immobilized EPS balls, and surface reactions in heterogeneous photocatalysis were more dominant than photo-induced radical reactions in aqueous solutions. Thus, TiO 2 -immobilized EPS balls were found to be an effective photocatalyst for photodegradation of organic compounds in aqueous solutions without further processes (i.e., separation, recycling, and regeneration of TiO 2 powder). Further study is in progress to evaluate the feasibility for usage of buoyant TiO 2 -immobilized EPS to inhibit the excessive growth of algae in rivers and lakes.