Enhancement photocatalytic activity of ZnO nanoparticles by silver doping with optimization of photodeposition method parameters.

The photocatalytic activity of silver-doped ZnO was tested by photocatalytic degradation of C.I. Acid Red 88 (AR88) as a model contaminant from monoazo textile dyes. Silver-doped ZnO was prepared by photodeposition (PD) method. Results show that silver-doped ZnO is more efficient than undoped ZnO at photocatalytic degradation of AR88. The PD method parameters such as irradiation time, calcination temperature and silver content of doping were effective on the photoactivity of silver-doped ZnO. Silver content had an optimum value of 0.5% for achieving high photocatalytic activity. In the real wastewater from a textile-dyeing factory color removal with pure and silver-doped ZnO after 18 min of irradiation were 45 and 90%, respectively.

The effect of particle size and crystal structure of titanium dioxide nanoparticles on the photocatalytic properties.

Titanium dioxide nanoparticles with different average diameter of particles (8, 18 and 27 nm) and different crystal structure (anatase and rutile) were used for degradation of C.I. Acid Red 88 (AR88) as a model compound. The degree of degradation of AR88 by TiO(2) nanoparticles under irradiation of UV-light (254nm) with TiO(2)-UV100 (8 nm diameter and 100% anatase) is lower than TiO(2)-Merck (27 nm diameter and 95% anatase). TiO(2)-P25 with structure of anatase and rutile (80:20) combination shows higher photoactivity than other samples such as TiO(2)-UV100 and TiO(2)-Merck. Kinetics of removal of AR88 with all of nanosized-TiO(2) particles is pseudo-first-order. The apparent reaction rate constant (k(ap)) for removal of AR88 in the presence of different nanosized-TiO2 particles decreases with increasing of AR88 initial concentration. For TiO(2)-P25 and TiO(2)-UV100 a linear relation and for TiO(2)-Merck a nonlinear relation between k(ap) and light intensity were obtained.