Soil is one of the basic elements of the ecosystem, one of the most important natural resources of the country, and also the material basis of human survival. Soil pollution can be divided into two major categories of inorganic and organic pollution; its repairing technology started in the late 1970s, and has been rapidly developing. Technology of photocatalytic degradation of soil is a new type of deepen chemical repairing technology applied in soil pollution, and it can be applied to the repairing process of polluted soil with pesticides and other organic pollutants and heavy metal ions.

 

Soil heavy metal pollution is a serious problem at home (China) and abroad, heavy metals in the polluted soil are mainly from atmospheric heavy metal deposition, pesticide and fertilizer application, irrigation, fertilizer sludge, heavy metal waste dumps and other ways. The most terrible thing is that, the damage and pollution it brings out in the soil is basically an irreversible process, because microorganisms in the soil can not break down these heavy metals, on the contrary, they through the accumulation or conversion to become more toxic compounds, or even enter the body through the food chain and endanger human health.

 

Photocatalytic oxidation technology of WO₃ photocatalyst can absorb the energy of sun light to produce hydroxyl and superoxide radicals, and turns the in the organic pollutants in the soil into non-toxic or low toxicity compound; the same time, it has efficient removal on the heavy metal pollution. Like the common inorganic contaminants of chromium ions (Cr⁶⁺) which has the highly carcinogenic, studies have indicated that, under the acidic conditions, WO₃ as a photocatalyst can effective turn chromium ions of +6 into +3, and make its toxic greatly reduced. Photocatalytic technology with its mild reaction conditions, not bring out a secondary pollution to environment, and use solar energy as a light source, in particular WO₃ with the wide band gap of 2.4eV~2.8eV which can respond to visible light, and thus to have a very broad prospects and good development potential.