Fenton And Electro-fenton Technology For Treatment Of Heterocyclic Organic Wastewater With Modified Catalyst

Removal of refractory organics from industry wastewaters was difficult by biological process. Advanced oxidation processes (AOPs) are efficient for its fast reaction speed, high purification efficiency, less secondary pollution and wide application. Fenton process, which uses iron ions as homogeneous catalyst and hydrogen peroxide as oxidizing reagent, has attracted more and more attention for its relatively stable, simplicity, mild condition, and suitability for practical application although the reaction mechanism still need more in-depth studies. The dynamics of multiple organics pollutants degradation should be investigated for the results of laboratory scale studies differ greatly in complex system problems.This paper focused on dynamic behavior studies of Fenton and electro-Fenton process treatment of the single and dual organics pollutants in the aqueous phase to reveal the Fenton reaction characteristics in treating multiple organic pollutant substrates. The main resluts were as followed:(1) To investigate the dynamic behaviors of Fenton process, methyl orange and Congo red were selected as simulation target pollutant respectively. The kinetics modeling indicated the Fenton oxidation reaction of the targeted pollutants followed the pseudo first-order reaction. Variation of the rate constants was not obvious in the temperatures ranging from30℃to60℃. The process has a wide range of temperature adaptation. The heterogeneous Fenton catalyst based on activated carbon were made by solution immersion method. The decoloration efficiency of0.028mmol/L methyl orange solution could reach90%above even pH increased from2.0to5.0. The concentration of Fe2+could maintain1.5mmol/L above during the procedure.(2) Electro-Fenton oxidation simulation using methyl orange as the target pollutant was also studied. The Ag-Fe bimetal wires cathode were fabricated by solution immersion method using the iron scraps of a mechanical processing factory. The concentration of H2O2generated by Ag-Fe bimetal wires cathode was46.9%more than the graphite plate cathode in this research experimental conditions. The concentration of Fe2+by Ag-Fe bimetal wires cathode was10.6times as graphite plate cathode. The Ag-Fe bimetal wires cathode could enhance the efficiency of electro-Fenton reaction. Internal Circulation Batch Electro-Fenton Reactor (ICBR) had been used for these bimetal wires cathodes. In the same conditions the kinetics reaction constant of ICBR was5.39times as the the kinetics reaction constant of ordinary squaree electrolytic cell reactor. This ICBR was stable and efficient in treating the targeted pollutant.(3) Fenton process to treat the dual organics pollutants in the aqueous phase was studied with phenol-methylene blue and sodium dodecyl sulfate (SDS)-methyl orange as model pollutant respectively. The results indicated that the presence of phenol reduced Methylene Blue discoloration rates. The-OH was thought to be more effective towards phenol oxidation instead of methylene blue for the high steric resistance of hydrosulfuryl in methylene blue. The degradation rate decreased with concentration of phenol increased. SDS could reduce the methyl orange degradation rate during the Fenton process. The ion-associate complex compounds of SDS and methyl orange maybe formed in aqueous phase,-OH tended to degraded SDS instead of target pollutant methyl orange. The degradation rates of methyl orange were reduced by SDS during Fenton process when the concentration of SDS was below CMC (Critical Micelle Concentration). The results indicated that degradation process was affected by the second compounds in the system. The characteristic of dual degradation process was related to the molecular structures of compounds.(4) Treatment of furfural industry wastewater by Fenton and Electro-Fenton processes was investigated in this study using the reactor with10L volume. Results indicated that Fenton process was suitable for industrial pretreatment for its high efficiency degradation and mild conditions. On the optimum experiment results, the Fenton-coagulation-PACT process had been established to treat furfural wastewater. The COD of furfural industry wastewater could decrease from13000mg/L to1900mg/L when the initial mass ratio of FeSO4, H2O2and COD reached2:1:10with reaction1hour. The performance was stable during the experiment and effluents reached the second grade standard of GB8978-1996. The drug cost of this process to treat furfural wastewater has reached the Y4.96per ton furfural industry wastewater. This process also showed the advantages of lower capital construction costs and economic benefits.Results of the research had enriched the theory of Fenton advanced oxidation technology. It also provided the science references to process control of Fenton technology in industrial wastewater treatment.