Research On Treating Methylene Blue By Modified Activated Carbon As Particle Electrode

As a new type of sewage treatment technology,the three-dimensional electrode method has the advantages such as high current efficiency,short mass transfer distance and small secondary pollution.It has a great significance in the treatment of difficult-biodegradable wastewater such as dye wastewater.Load-type particle electrodes were synthesized by impregnation method using Granular activated carbon(GAC)as the support and single metal oxide or composite metal oxide as the active component.The performances on methylene blue decolorization for different particle electrodes were investigated and the results showed that Mn-Co-Ce/GAC performed the best.Decolorization rate and COD removal efficiency with the three-dimensional electrode reached 94.31%and 65.11%,respectively.While for the two-dimensional electrode,the corresponding efficiencies of 58.52%and 23.15%were achieved.The effect of aeration conditions on the electrocatalytic oxidation was studied.The result showed that the aeration provided sufficient O2 for the three-dimensional electrode system,which significantly improved the degradation of methylene blue.By adding t-butanol,it demonstrated that OH played an important role in the degradation of methylene blue.The performances of Mn-Co-Ce/GAC particle electrode for the degradation of methylene blue under different reaction conditions(reaction time,plate spacing,applied voltage and auxiliary electrolyte concentration)were studied.Experimental results showed that the optimal operating conditions were as follows:the reaction time,the voltage,Na2SO4 concentration and electrode distance were 90 min,20V,0.15 mol·L-1 and 4 cm,respectively.The corresponding color and COD degradation rate reached about 80%and 50%after 30 cycles,which indicated that the Mn-Co-Ce/GAC particle electrode exhibited good stability on the degradation of methylene blue.The performance of the particle electrode on the degradation of methylene blue recovered greatly after regeneration.The color and COD degradation rate of methylene blue solution was 92.33%and 58.96%,respectively.The results of UV-Vis absorption spectroscopy and LC-MS(liquid chromatography-mass spectrometry)indicated that open-chain reaction of N,S heterocycle first occurred and then he substituted benzene or small molecule organic matter was generated.This showed that the Mn-Co-Ce/GAC particle electrode had a good degradation performance for on methylene blue.The BOD5/CODcr increased from 0.12 to 0.58,which indicated that the biodegradability of methylene blue solution was greatly improved after the treatment of three-dimensional electrode.The kinetic analysis showed that the decolorization of methylene blue followed first-order kinetics indicating that the methylene blue solution treated with Mn-Co-Ce/GAC particle electrode can achieve good decolorization in a short period of time.In comparison with two-dimensional electrode,using three-dimensional electrode consumed less energy.Treating on organic wastewater of high concentrations using three-dimenisional electrode is more conducive to saving energy.