الفهرس 
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Abstract
Titanate nanotubes exhibited a higher photocatalytic activity compared to anatase powders, titanate nanowires and titanate nanoparticles.
The degradation values show non linear dependence on methylene blue initial concentration and it decreases with the increa.se of its concentration.
For 5 ppm dye solution, at 0.2 g Ti02 nanowires/ 400 ml of dye solution and pH of 12.6 the percentage dye degradation of 97.8% was accomplished after 90 minutes of reaction time. This corresponds to 97.3 and 95% for 10 and 15 ppm dye solutions, respectively.
In case of Ti02 nanoparticles, the percentage dye degradation was 97.6, 97.2 and 93% at pH 12.6 and 0.2 g catalyst/400 ml of solution, for 5, 10 and 15 ppm dye solutions, respectively; all values are calculated after 90 minutes of reaction time.
In case ofTi02 nanotubes, the percentage dye degradation was 98.6,98.5 and 95.18% for solutions with initial dye concentrations 5, 10 and 15 ppm, respectively. These results are obtained at 0.2 g catalyst/400 ml of dye solution md pH value of 12.6.
The photocatalytic degradation of dye increased with increasing the pH value, sing 0.2g nanotubcs/400 ml of solution with 5 ppm solution, the percentage
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dye degradation was 98.6, 93.8 and 92.7: at pH values 12.6, 7 and lA, ~spectively. When using nanoparticles, the maximum degradation obtained as 94.6,56.6 and 42% at pH values 12.6,7 and lA, respectively. When using anowires, the percentage dye degradation were 97.8, 70 and 63% at pH values 12.6, 7 and 1.4, respectively. All tests are run on 5 ppm dye solution with catalyst concentration 0.2 g/ 400 ml of solution.
7. Investigation of the effect of catalyst concentration on the percentage degradation indicated that increasing the catalyst concentration (up to 0.2 g/400 ml of solution) increases the percentage dye concentration. For Ti02 nanotubes, percentage dye degradation of 96.2, 97.02 and 98.6 % was obtained when using catalyst concentrations 0.1, 0.15 and 0.2 g/ 400 ml dye solution, respectively. The conesponding values were 95.4, 96.6 and 97.8 % for nanowires and 94.6, 96.5, and 97.6 % for nanoparticles. All tests are run on 5 ppm solutions at pH 12.6.
8. The Response Surface Methodology ((RSM) is used to optimize the operating parameters affecting the photocatalytic degradation of methylene blue using artificial source ofUV . Using Ti02 nanowires, the optimum values were 8.63 ppm; 0.16 g/ 400ml of dye solution and 12.60 for initial concentration of dye, catalyst dosage, and pH value, respectively. In case ofTi02 nanotubes, the optimum \alues were 7.68 ppm dye solution, 0.19 g catalyst/ 400ml of dye solution and pH value 12.58.