photocatalytic degradation of some organic dyes under solar light irradiation using tio2 and zno nanoparticles

nanoparticles of the zno and tio2 were synthesized and the physicochemical properties of the compounds were characterized by ir, x-ray diffraction (xrd), scanning electron microscopy (sem) and transmission electron microscopy (tem). the xrd patterns of the zno and tio2 nanoparticles could be indexed to hexagonal and rutile phase, respectively. aggregated nanoparticles of zno and tio2 with spherical-like shapes were observed with particle diameter in the range of 80-100 nm. these nanoparticles were used for photocatalytic degradation of various dyes, rhodamine b (rhb), methylene blue (mb) and acridine orange (ao) under solar light irradiation at room temperature. effect of the amount of catalyst on the rate of photodegradation was investigated. in general, because zno is unstable, due to incongruous dissolution to yield zn(oh)2 on the zno particle surfaces and thus leading to catalyst inactivation,the catalytic activity of the system for photodegradation of dyes decreased dramatically when tio2 was replaced by zno.