Research on the photocatalytic degradation of dyes and other organic pollutants become an interesting topic in the last two decades. Under UV irradiation, investigation and optimization of various experimental parameters were done for the photocatalytic degradation of fast green dye (FG) in the presence of titanium dioxide (TiO2) suspension. Initial dye concentration, photocatalyst dosage, and solution pH were the study parameters. Results showed that the rate at which FG dye degraded was accelerated by increasing the TiO2 dose. However, the degradation rate was adversely impacted by the rise in FG dye content from 3 to 9 mg/L. It was found that the highest percentage of color removal occurred when the pH of the medium was 6.5. FG was found to be degraded process reached equilibrium in 50 minutes using TiO2 photocatalyst, proving that it is an effective catalyst for the process. Additionally, the kinetics of FG dye degradation was studied, and it was followed by the pseudo first-order kinetics.

This work investigates the electro-catalytic degradation of alizarinblack dye in an electrochemical cell using Fe as anode and Al as cathode. The influence of initial dye concentration, effect of salt, pH, change of temperature and effectofchange of applied voltage have been studied in addition, the influence of semiconductor dose has studied as well. In the current work roughly total removal of 70 mg/L of dye occurred in 16 min only. The results showed that effect of both electrolyte concentration and applied voltage was positive if combined together and the rate of degradation in neutralmedium was the best for degradation of Alizarin black dye.

he photo-catalytic degradation of Toluidine Blue dye (TB) in aqueous suspension solution has been studied utilizing fluorescence light and using Zinc oxide (ZnO) as a semiconductor at variety working factors. The studied parameters were concentration of dye, semiconductor dose and the influence of pH. The result shows that expanding of ZnO dose from 20 to 60 mg/L increases the removal rate of TB dye. On the other hand, the adding of concentration from 5 to 15 mg/L show negative effect on the rate of photo-degradation. It has been denoted that the percentage of dye degradation come to the peak value at high acidic medium. 11 % of TB dye was adsorbed, in dark condition, by ZnO. In addition, the kinetics of degradation has been examined and the degradation was found to take after pseudo-first order kinetic model.

The adsorption of Acid Alizarin Black (AAB) dye (C.I. 21725) on zinc oxide was investigated in this study. The adsorption was carried out under different operating conditions. The operating conditions were contact time, adsorbent dosage (10, 30, 50, 70 and 100 mg), initial dye concentration (10, 20, 30, 40, 50, 60 and 70 mg/L), the pH of the solution (2, 4, 6, 7, 8, 10 and 12) and temperature (20, 30, 40, 50 and 60°C). The removal percentage of dye on ZnO decreases from 67% to 54% with increase in initial dye concentration from 10 to 70 mg/L, respectively. It was found that the increasing of ZnO dosage enhanced the dye removal. The increasing of temperature insignificantly enhanced the removal of dye. The study reports that the best pH of solution for the adsorption of AAB on ZnO were 7 and 8. The adsorption data have been analysed using Langmuir, Freundlich and Temkin. It is indicated that the adsorption of dye onto ZnO was endothermic. The uptake process of AAB obeyed the pseudo second order kinetic expression. Removal of Acid Alizarin Black Dye from Aqueous Solution by Adsorption Using Zinc Oxide. Available from: https://www.researchgate.net/publication/297032256_Removal_of_Acid_Alizarin_Black_Dye_from_Aqueous_Solution_by_Adsorption_Using_Zinc_Oxide [accessed Mar 9, 2016].