Photodegradation of a real textile dyeing wastewater taken from Hilla textile factory in Babylon Governorate, Iraq have been investigated. Photocatalytic degradation was carried out over suspensions of titanium dioxide or zinc oxide under ultraviolet irradiation. Photodegradation percentage was followed spectrophometrically by the measurements of absorbance at λmax equal to 380 nm. The rate of photodegradation increased linearly with time of irradiation when titanium dioxide or zinc oxide was used. A maximum color removal of 96% was achieved after irradiation time of 2.5 hours when titanium dioxide used at 303K and 82% color reduction was observed when zinc oxide used for the same period and at the same temperature. The effect of temperature on the efficiency of photodegradation of dyestuff was also studied. The activation energy of photodegradation was calculated and found to be equal to 21 ± 1 kJ mol-1 on titanium dioxide and 24 ± 1 kJ mol-1 on zinc oxide.

The ternary NiO-CoO-MgO catalyst in three ratios 20:20:60, 25:25:50, and 30:30:40 for these component oxides respectively, were synthesized by co-precipitation method of their carbonates by addition of a precipitate agent in basic media, and then calcinated these carbonate to obtain of mixed oxides. The prepared catalysts were characterized by using Powder X-Ray Diffraction (PXRD), Fourier Infrared spectroscopy (FT-IR), and Atomic Force Microscopy techniques (AFM) were used for identification of the prepared catalysts. The result showed that the particle size of these catalyst ratios, were in the nano range and the smallest size was 25:25:50. The investigation of catalytic activity of prepared catalysts was done by photo decolorization of Celestine blue B dye from simulated industrial wastewaters in aqueous solution. The decolorization efficiency of dye reached 99.9% after irradiation time for 1 h. Study the effect of different reaction conditions such as the pH of the medium, the weight of semiconductor and temperature of mixture reaction were shown that the maximum degradation was observed in conditions at pH = 4, catalyst dosage = 0.08 g, and temperature = 303 K.

The spinel co-catalyst NiO-Mn2O3/ZnO2 in two different ratios (0.5:0.5:2) and (1:2:1) of the components oxides were prepared using coprecipitation method of their metal hydroxides. This method was performed in basic medium (pH 9), using sodium carbonate as a precipitated agent. The precipitated samples dried at 120 ºC overnight and then calcinated at 650 ºC for three hours. The prepared spinel co-catalyst was investigated using powder X-ray diffraction, Fourier transfer infrared spectroscopy, energy-dispersive X-ray spectroscopy and atomic force microscopy. According to spectroscopic studies and magnetic properties, the obtained co-catalyst was a normal spinel type. The catalytic activity of prepared co-catalysts was conducted by following photocatalytic degradation of Bismarck Brown G dye. From the obtained results, the best ratio of spinel catalyst was (0.5:0.5:2) optimized, which achieved a higher activity for removal percentage (97 %) dye.

The spinel semiconductor oxide found in the formula AB2O4 for normal spinel structure, where A is a divalent cation that usually occupy the tetrahedral sites and B is a trivalent cations that normally occupy the octahedral sites in the spinel cubic structure. Another type of spinel structure is an inverse has the form B(AB)O4, where B is a trivalent metal cation, half of this cation occupy the tetrahedral sites and another occupy the octahedral sites, A is divalent metal cation occupy an octahedral site in spinel [1,2]. The most interesting spinel structure materials in the magnetic and electrical field usually include iron and cobalt at various oxidation states [3-5]. The transition metal oxides which defined are compounds consist of oxygen atoms coalescence to transition metals [6,7] and used as a photocatalysis in wastewater treatment [8], these catalyst were capable of absorbing light and creating electronhole pairs that allow electronic transition in the reaction because of the formation of positive holes, which resulted from the transfer electron from the valence band to the conduction band of semiconductor by absorbing energy from UV light, visible light or both producing an electron/hole pair (e-CB/h + VB) which is able to reduce and/or oxidize compound and degrade of pollutants in aqueous solution by using solid heterogeneous catalyst such as mixed metal oxides, which have wide applications as catalyst

A modern and easy procedure performed using the spectrophotometric method and estimating of Ni (II) in alloy samples. Using a ligand 1-((4-(1-(2-hydroxyphenylimino) ethyl)phenyl)diazenyl)naphthalene-2-ol (HPEDN) and a synthesis of the azo-schiff reaction by reaction p-aminoacetophenone with 2-naphtol in first step and reaction of product with 2-aminonaphthol, Ligand and its complex were identification by using UV-Vis. Spectrophotometry (326nm for ligand (HPEDN), 516nm for complex(Ni-HPEDN)), FT-IR, 1H-NMR, and 13C-NMR. The optimal conditions in the complex composition were studied at pH=9, temperature 25°C, and time 15min. The best concentration was found for Ligand (2×10−4 M), Under optimum conditions concentration ranged from (1.1-7.1) μg/mL of Nickel(II) were obeyed Beer‘s Low, with Molar Absorptivity 0.2648×104L.mol−1.cm−1. Limit of Detection(LOD) and Limit of Quantification(LOQ)were 0.3928 and 1.3082μg.mL−1 respectively. The stoichiometric composition of the chelate is 1:2 (Ni:HPEDN). This method is Sensitive, accurate and rapid spectrophotometric method. The results obtained were compared with flame atomic absorption spectrometry method and results are in conformity.