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ZnO nanopowders were prepared by solution combustion method (SCM). The ZnO nanopowders synthesized using Zn(OH) 2 and glycine as an oxidant and a fuel (with fuel/oxidant ratio, F/O=0.8), showed excellent crystalline and photocatalytic characteristics. In order to evaluate the photocatalytic reactivity of the prepared ZnO nanopowder, it was tried to decompose total organic carbon (TOC) from aqueous phenol solution. Several kinds of TiO 2 nanopowders were also tried to compare the photocatalytic reactivity. Surprisingly, SCM ZnO nanopowder shows 1.6 fold higher destruction rates of the organic pollutant than P-25 TiO 2 nanopowder that is known as a kind of standard photocatalyst.

ZnO nanopowders were prepared by solutioncombustion method (SCM). The SCM ZnO nanopowders were treated by five different dispersants. They were used as photocatalysts to remove Ag + ions from used photographic developing solutions. The Ag + ion removal rates by the dispersed SCM ZnO nanopowders were then compared with those by other photocatalyst powders such as commercial ZnO(Junsei, Japan), P25 TiO 2 (Degussa, Germany) and TiO 2 powder prepared by homogeneous precipitation process at low temperature (HPPLT). The dispersion of SCM ZnO nanopowders in the solution enhanced the Ag + ion removal rate up to about 13 folds compared with P25 TiO 2 nanopowders and 2 folds to SCM ZnO nanopowders without dispersion. Sodium hexametaphosphate was the most effective dispersant among them.

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Nano-sized ZnO powder was prepared by "solution-combustion method (SCM)." The ZnO powder using Zn(OH)2 and glycine as an oxidant and a fuel (F/O = 0.8), showed good powder characteristics, such as average grain size of 30 nm and the specific surface area of 120 m2/g. and it was used as a semiconductor photocatalyst to remove Cu ions from aqueous Cu-EDTA solution. The result was then compared with other semiconductor photocatalyst powders such as titanium dioxide (TiO2) powder (P25, Degussa) and TiO2 powder prepared by homogeneous precipitation process at low temperature (HPPLT). The SCM ZnO nanopowder showed excellent photocatalytic properties. The Cu++ ions were completely removed from the solution within 90 min. However, for the other two powders, no complete removal of the ions was observed within the reaction time of 180 min. The ZnO powder synthesized at the fuel/oxidant ratio of 0.8, showed higher PL intensity at UV region than the other photocatalytic powders. The superior photoreduction ability of SCM ZnO nanopowder might be due to its excellent UV absorption capacity.