Photocatalytic oxidation of organic pollutants on titania–clay composites

TiO2/Ca-montmorillonite composites were prepared by wet grinding in an agate mill. Positively charged TiO2 nanoparticles are bound to the surface of the negatively charged montmorillonite layers via heterocoagulation; the clay mineral is used as adsorbent and support for the photooxidation process. Aquatic solution of 0.5 mM phenol was degraded by irradiation with UV–VIS light (λ = 250–440 and 540–590 nm) in suspensions of TiO2–clay composites and significant photodegradation was observed at 40–60% TiO2/Ca-montmorillonite compositions. Synergistic effect was detected at solid/liquid interface for degradation of phenol and at solid/gas interface in the recycling flow reactors for photooxidation of ethanol and toluene vapors.