Synergistic Degardation Of Dyeing Wastewater By Ultrasound-Fenton Method

Azo dyes wastewater is not only high chromatic, strong noxious, butalso difficult to degrade and easy to discompose to carcinogenic aromaticamine under deoxidization condition. So, azo dyes wastewater must betreated urgently. In this thesis, reactive-red X-3B solution, which has azodyes structure, was studied by Ultrasound-Fenton reagent techniques. Withthe degradation of reactive-red X-3B and the change of structure reflectedby UV spectrum as criteria, the influence of the technical conditions on thedisposal of reactive-red X-3B were systemically studied. Furthermore,decomposition mechanism of the azo dyes was studied and the ratio ofBiochemical Oxygen Demand to Chemical Oxygen Demand was used forthe dye's biodegradability study.Degradation of simulated reactive-red X-3B wastewater by ultrasonictechnology, Fenton reagent oxidation, and a combination of the twoprocesses was studied. It was found that the degradation by ultrasonictechnology or Fenton reagent oxidation alone was insignificant, with adegradation rate-of 5% and 45% respectively; while it was greatly improvedwhen the two processes were combined, with a degra.dation rate up to 90%,which showed that these two processes presented a good synergetic effect.The degradation of reactive-red X-3B by the combined two processes couldbe described by second-order kinetics model.The effect of many factors such as ultrasonic power, probe diameter, pH, temperature, concentration of FeSO₄ and H₂O₂ on the degradation ofreactive-red X-3B was investigated. The results showed that thetemperature had little or even an adverse effect on the degradation. Thedegradation rate was strongly pH dependent and increased with decreasingpH. On the contrary, the degradation rate was increased with increasingultrasonic power and FeSO₄ concentration, but it was increased slightlywhen FeSO₄ concentration was more than 0.045mmol/L, however, therewas an optimal H₂O₂ concentration for effective RR2 degradation.Furthermore, the orthogonal analyses were conducted to investigate suchsensitive effect factors as H₂O₂ concentration, FeSO₄ concentration,ultrasonic power and pH, and the optimum applicable parameters weredetermined.Finally, the ratio of Biochemical Oxygen Demand to Chemical OxygenDemand is used for the dye's biodegradability study. The result showed thatthe dye's biodegradability has been heightened after ultrasonic technologyand Fenton reagent acting on it.