The stability of photoactive kaolinite/TiO2 composite

Nanoparticles are increasingly used in many applications. However, not only their positive properties are important but also their potential impact on environment. This article deals with the stability and potential toxicity of photoactive composite kaolinite/TiO2 with verified photoactive properties. Clay mineral kaolinite, calcined kaolinite and dried or calcined composite containing of photoactive oxide TiO2 were studied by leaching test, aquatic toxicity tests and molecular modeling. Materials were leached in deionized water and acidic or basic extraction agents. The conductivity, pH, and leached elements were determined in leachates. Desmodesmus subspicatus or Chlorella vulgaris were used to the algal toxicity tests and the inhibition of growth was monitored. Changes in clay mineral and photoactive composite were evaluated on the basis of leached elements and results of aquatic toxicity tests.