PHOTOCATALYST FOR DECOMPOSING NITRATE ION IN WATER AND DECOMPOSING AND REMOVING METHOD OF NITRATE ION

摘要

PROBLEM TO BE SOLVED: To decompose and remove nitrate ion contained in the under ground water, the river water, the water and sewage, the industrial waste water or the like with a small quantity of photoenergy. SOLUTION: Nitrate ion in water is high efficiently decomposed and removed allowing a photocatalyst for decomposing nitrate ion in water, which is expressed by a formula, Ar My B8-y O16 (in the formula, A represents one or more kinds of elements selected from the group consisting of K, Rb, Cs, Ca, Ba and Na, M represents a 2-valent or 3-valent metal element, N represents Ti or Sn, Where, when A represents Na element, M represents Cr. (x) and (y) are respectively 0.7<=x<=2.0 and 0.7<=y<=2.0) and is composed of a hollandite type crystalline phase, to contact with nitrate ion and a reducing agent in the water while irradiating with light.