Degradation Of Acid Orange7in Aqueous Solution By Zero-valent Aluminum

Since the varieties of dyes becoming more and more miscellaneous，and towarding to thedirections of anti-photolysis, anti-oxidation, anti-biological oxidation, the treatment of dyewastewater increasingly more and more difficultly. Many researches had been carried outabout dye wastewater treatment in many countries. To effectively address the shortcomings oftraditional techniques, the advanced oxidation processes (AOPS) was investigated because ofits enormous potential and unique advantages. The most significant feature of AOPs is thehydroxyl radical (·HO) for the primary oxidant to react with the organic compounds,oxidative decomposition of organic matter so as to achieve the final product degradation untilCO2and H2O purposes.Oxidation-reduction potential of the zero-valent aluminum (E0=-1.67V) is lower than theFe0, It’s can be used as a effective strong reducing agent. Under acidic conditions, zero-valentaluminum can produce·HO which has a strong oxidation of organic pollutants in water by thereduction of dissolved oxygen. In addition, the reaction system is simple, mild conditions andlow cost, so it is a promising advanced oxidation process. A typical azo dye Acid Orangepollutants (AO7) was investigated in this paper. From the experimental feasibility factors,such as the perspective of the practical application of zero-valent aluminum H+/O2system andzero-valent aluminum H+/O2combined ultrasound system (ZVAl-US) to carry out thefollowing studies:(1) The feasibility of the method, influence factors and strengthen about the AO7wastewater removal under system of zero-valent aluminum H+/O2were discussed. Resultsshowed that in acid solution (pH <3.5), the system has a excellent removal effect on AO7. Atthe condition that pH is2.5, aluminium powder concentration is20g/L, initial AO7concentration is20mg/L and temperature is20℃, removal rate of AO7reached96%within40minutes. In the process of reaction, temperature, dosage of aluminum powder, the additionof ferrous iron in a certain range were positive correlation with the degradation of AO7; pH,intial concentration of wastewater and the addition of EDTA were negative correlation withthe degradation of AO7rate. (2) The different processes, sole ZVAl, sole US, and US-ZVAl, were carried out as thecontrol experiments for the degradation of AO7. And further studied about the influencefactors of ZVAl-US system to remove AO7was carried. The results showed that the coupledUS-ZVAl process was much more effective than ZVAl reaction or ultrasound irradiationalone. When aluminum powder addition is2g/L, ultrasound power is300W, and the initialpH value is2.5, removal rate of AO7reached87%within30minutes. In ZVAl-UScoordination system, increase of the amount of aluminium powder and reasonable increase ofpower were good for the degradation of AO7; And increase of the pH, higher concentration ofwastewater would reduce the degradation of AO7rate.(3) Regarding the actual dyeing wastewater from a printing house of Jinan as theresearch object, explored the effect of ZVAl-US system to degrade actual azo dye wastewater.In optimal conditions, the actual dye wastewater which had been diluted10times weredegraded, and the results showed that the degradation rate of dye wastewater reached79%and COD removal rate reached60%within2hours. The phenomenon proved that ZVAl-USsystem has good degradation effect for actual azo dye wastewater.