In this article photocatalytic degradation of orange G dye was carried out using titanium dioxide nanoparticles under UV irradiation. The amount of photocatalyst, concentration of orange G dye, effect of light intensity and effect of PH were studied as variables. The highest photocatalytic degradation of orange G dye was observed at 0.14 gm/100cm 3 of titanium dioxide nanoparticles and 15ppm of dye. Orange G dye photocatalytic degradation was favorable in the PH 6.4 and 8.22 mW/cm 2 light intensity. Photocatalytic degradation of orange G dye follow the first order of reaction .photocatalytic degradation of orange G dye has been studied using different concentrations of titanium dioxide nanoparticles suspended in an aqueous solution of orange G dye irradiated by 125 watts ultraviolet radiation in a vessel reactor at room temperature, with 10 cm 3 /min air bubble has been passed through the solution .Photocatalytic degradation of orange G dye presence of light and catalyst is essential for the degradation. Increasing dye concentration resulted in decreased photocatalytic degradation efficiency. The percentage efficiency of degradation reactive blue equals 93.98 % .The activation energy has been calculated it was found equal to 22.29 ±1 kJ.mol-1. All experiments are determined using UV-visible spectrophotometer analyser.

The organic pollutant methyl violet dye photocatalytic degradation has been investigated using the UV irradiation and TiO2 as a catalyst. The degradation process included the study of the initial dye concentration, light intensity, catalyst weight, the effect of intensity of light, and effect of temperature to approach the best conditions for the optimum photo-degradation efficiency of dye. The optimum photocatalytic degradation of methyl violet dye was at 0.15 g/100cm3 of dosage mass of TiO2 and 10 ppm of the dye. Photocatalytic degradation of methyl violet dye was at 9 mW/cm2light intensity. The percentage efficiency of degradation methyl violet dye equals 97.46%.

Six novel aromatic azo dyes were synthesized from 4-amino-2-nitrobenzoic acid with phenol, catechol, resorcinol, hydroquinone, salicylic acid and acetylsalicylic acid with very good yield. These azo dyes confirm by FTIR, CHNS and study the photo stability used TiO2 and ZnO. The photocatalytic degradation of novel aromatic azo dyes was investigated using TiO2 and ZnO as a catalyst under 125 watts UV lamp. A series of experiments was performed to reaching to the optimum condition of degradation. The photocatalytic degradation of azo dye follows the first order reaction. In all experiments photocatalytic degradation of the azo dye has been studied using different weight of TiO2 and ZnO suspended in an aqueous solution of azo dye irradiated by irradiated by 125–UV lamp in 100 cm3 a vessel reactor at room temperature with 10 cm3/min air bubble has been passed through the solution. In addition, all result was measured using UV-Visible spectrophotometer.

The new azo dye [4-(4-hydroxy-2-methylnaphthyl)diazenyl]benzoic acid was synthesized by the reaction of 2-methyl-1-naphthol with p-amino benzoic acid. The photcatalytic degradation of azo dye has been investigated by using zinc oxide and cadmium sulfide. This degradation was carried out by the irradiation of aqueous suspended solutions containing different concentrations of this dye using 0.11 g/100 mL of metal oxide (semiconductors) ZnO and CdS. A mercury lamp 125 W in a Pyrex photoreaction cell of 100 mL at room temperature was used as an irradiation source. The effect of the catalyst on the photocatalytic degradation of the prepared dye was studied via several experiments at different conditions, where they involve the effect of the catalyst mass and the effect of the dye concentrations. The irradiated solutions were studied using UV-Vis spectrophotometer. It has been the performance of photocatalytic system that using ZnO was observed to be better than cadmium sulfide system for degrade the azo compound from its aqueous solution.                     KEY WORDS: Photocatalytic, Degradation, Semiconductors, Zinc oxide; Cadmium sulphide, Azo dye   Bull. Chem. Soc. Ethiop. 2020, 34(3), 463-469. DOI: https://dx.doi.org/10.4314/bcse.v34i3.3

Global water pollution caused via dye and pollutants have been reported to need touched an alarming level. These hazardous pollutants pose important threats to ecosystem , humans , due to their carcinogenicity, mutagenicity and toxicity. Different method needed to removal of dyes from waste water, like chemical oxidation, extraction, physical adsorption, electrochemical treatments and zonation. Though, these methods conventional are constrained via little efficiency great cost ,stability, and harmful formation through-produces. Wastewater from production dyestuff is one of the main pollutants water. Different ways have been useful for the remediation of water contaminated. In the present study, the utilize of low-cost, abundantly available, greatly efficient and simply obtained ecofriendly adsorbents like clay and activated carbons have been reported as an alternative to the current expensive ways of dye removal from aqueous solution. .About of the methods depend of the several will yield from (AC). kind of AC is useful: (1) it acts as a dye adsorbent, not only in straight forward methods of the adsorption but too in AC-improved clotting and filtration membrane methods; (2) it strong produces of the oxidizing agents (typically, radicals (_OH)) in electro chemical oxidation dye; (3)it catalysis _OH production in (AOPs); (This reviews kind of clay and AC in dye de-colorization, assesses the possibility of each AC-altered de colorization method and discusses perspectives on future research.