INTRODUCTION: PHOTODEGRADATION IS DEGRADATION OF A PHOTODEGRADABLE MOLECULE CAUSED BY THE ABSORPTION OF PHOTONS, PARTICULARLY VISIBLE AND ULTRAVIOLET LIGHT. A COMMON PHOTODEGRADATION REACTION IS OXIDATION IN PRESENCE OF OXYGEN, OZONE OR OTHER OXIDIZING AGENT SUCH AS HYDROGEN PEROXIDE OR CHLORINE. THE DECOLORIZATION OF TEXTILE DYES AFTER PHOTODEGRADATION PROCESS IS A USEFUL WAY FOR WASTE WATER TREATMENT IN INDUSTRIAL PLANTS [1]. TEXTILE DYES ARE USED NOT ONLY IN THE TEXTILE INDUSTRY BUT ALSO USED IN MANY INDUSTRIAL FIELDS SUCH AS PAPER PRODUCTION, FOOD PROCESSING, AND COSMETICS. TEXTILE INDUSTRIES PRODUCE A LARGE NUMBER OF WASTE COLORFUL WATER THAT IS TOXIC AND NON BIOLOGICAL DEGRADABLE [2].

ZNO IS A SELF-EXCITATION SEMICONDUCTOR, ONE OF THE MOST IMPORTANT PROMISING MATERIALS WHICH HAVE BEEN APPLIED TO MANY FIELDS SUCH AS TRANSPARENT CONDUCTIVE CONTACTS, SOLAR CELLS, LASER DIODES, ULTRAVIOLET LASERS, THIN FILM TRANSISTORS, OPTOELECTRONIC AND PIEZOELECTRIC APPLICATIONS, SURFACE ACOUSTIC WAVE DEVICES AND PHOTOCATALYST [1]. RECENTLY, MICRO- AND NANOSTRUCTURED ZNO HAS BEEN OBTAINED BY USING VARIOUS PHYSICAL AND CHEMICAL TECHNIQUES [2]. ALSO OWING TO HIGH PHOTOCATALYTIC ACTIVITY, LOW COST AND ENVIRONMENTALLY FRIENDLY FEATURE, ZNO HAS BEEN WIDELY USED AS A PHOTOCATALYST. HOWEVER, DUE TO A WIDE BAND GAP OF 3.37 EV, POOR PHOTON ABSORPTION OF ZNO LIMITS ITS APPLICATION IN VISIBLE LIGHT PHOTOCATALYST [3]. IN ORDER TO SHIFT THE OPTICAL ABSORPTION OF ZNO INTO THE VISIBLE REGION, ONE POSSIBLE APPROACH IS TO DOPE TRANSITION METAL IONS INTO ZNO PHOTOCATALYST. METAL-DOPED ZNO NANOMATERIALS PERMIT TUNING OF CHEMICAL AND PHYSICAL PROPERTIES BY THE INCORPORATION OF THE DOPANT IN LATTICES OF ZNO [4].IN THIS WORK, TRANSITION METALS (MN, CO) DOPED ZNO NANOPOWDERS PREPARED BY A HYDROTHERMAL METHOD. THE PHASE AND MORPHOLOGY STUDIES HAVE BEEN CARRIED OUT BY XRAY DIFFRACTION, SCANNING ELECTRON MICROSCOPY (SEM) AND TRANSMISSION ELECTRON MICROSCOPY (TEM) RESPECTIVELY.ALL THE SAMPLES OF THE PRESENT INVESTIGATION ARE FOUND TO HAVE HEXAGONALWURTZITE STRUCTURE AND CRYSTALLITE SIZES ARE FOUND TO VARY FROM 25 NM TO 30 NM. DIFFERENT MOLAR RATIOS OF METAL CATION DOPING IN ZNO STRUCTURE IS TESTED.THE PHOTOCATALYTIC ACTIVITY OF M-DOPED ZNO WAS EXAMINED ON THE DEGRADATION OF THE METHYL ORANGE (MO). LOGIN CATIONS IN ZNO LATTICE STRUCTURE CHANGE IN THE ENERGY BAND GAP. THIS CAUSES THE USE FROM VISIBLE LIGHT INSTEAD OF UV LIGHT FOR THE ZNO PHOTOCATALYTIC ACTIVITY FOR DEGRADATION OF DYES IN WASTEWATER. ZNO0.9CO0.1O SHOW 99% DEGRADATION IN 60 MIN.