Simultaneous Degradation Of Reactive Brilliant Blue And Bioelectricity Generation Using A Persulfate-cathode Microbial Fuel Cell

An anthraquinone dye Reactive Brilliant Blue KN-R was taken as targetpollutant, zero-valent iron (Fe0) and ferrous iron (Fe2+) activated persulfate (PDS)was used to degrade the KN-R as contrast systems, this paper investigated atwo-chamber MFC using Fen(Fe0and Fe2+) activated PDS as the cathode solutionsto degrade KN-R and recover electricity simultaneously under different initial pH,Fenand PDS dosage. The results are shown below:（1） In Fe2+/PDS system, the KN-R degradation process could be divided intofast and slow stages, which followed the first order reaction kinetics model. TheKN-R degradation rate was increased first and decreased later with increase of initialpH and Fe2+dosage, however increased with improvement of initial PDSconcentration. In Fe0/PDS system, the KN-R degradation process followed the firstorder reaction kinetics model within180min. The initial pH and Fe2+dosage hadless effect on the KN-R degradation. Maximum KN-R degradation occurred atneutral condition (pH=7), was93.12%. The speed of degradation increased with theconcentration of the initial Fe0dosage. The degradation reaction rate constant was0.0414min-1at Fe0=448mg/L and PDS=2mmol/L.（2）In order to achieve the best running state of MFC, anode HRT anddifferent cathode electron acceptor were studied firstly. The power density had themaximum was312.17mW/m2, when PDS was used as the cathode electron acceptorand HRT was18h. Then the Fe2+/PDS and Fe0/PDS systems were taken as thecathode solutions to degrade KN-R and produce electricity simultaneously. In the Fe2+/PDS-MFC system, the second-order reaction kinetics model could represent thedegradation process of KN-R, effectively. The same as the Fe2+/PDS system, theFe2+/PDS–MFC system did not break the initial pH and Fe2+dosage on the KN-Rdegradation, but it would increase the PDS consumption. When the initial pH was5,the KN-R was almost degraded. The power generation was restrained by initial pHmore than the Fe2+dosage. With increasing of PDS, the electrogenesis capacityenhanced. The maximum power density was294.07mW/m2at present of pH=3,PDS=2mmol/L, Fe2+=1mmo/L.In the Fe0/PDS-PDS system, the same as the Fe0/PDS system, the degradationprocesses of KN–R also followed the first-order kinetics equation. In addition, it waslittle influenced by pH value, Fe0dosage and PDS concentration. The research canobtain a high degree of KN-R degradation rate under the condition of the variousparameters of the present study and the degradation rate of pollutants was obviouslyhigher than that of in Fe0/PDS system. Compare with the Fe0/PDS system, the KN-Rdegradation reaction rate increased4.26-7.39times under the condition of the sameFe0dosage. The electricity generation capacity is lower than the Fe2+/PDS-MFCsystem and is largely influenced by various parameters. At the optimum conditions,the KN-R degradation rate was98.98%and the power density was127.66mW/m2inthe presence of pH=3, PDS=1mmol/L, Fe0=28mg/L.(3) This study examined the removal rate of TOC and the spectrum degradationof KN-R under the optimum condition in the four systems. Results showed that inthe system of Fe0/PDS–MFC, TOC removal rate reached the maximum. TOCremoval rate in Fe2+/PDS system is higher than that of in the Fe2+/PDS–MFC system.The reason is that activation rate of PDS with SO4–·is less in the former, whichresults in the less mineralization rate of pollutants within a limited time. Theanalysis from the UV-vis spectroscopy of KN-R degradation process showed thatSO4–·generated in the system destroy conjugated system of2-sulfonic acid-1,42amino anthraquinone and discolor the reactive brilliant blue KN–R. And then reacts with anthraquinone structure and benzene ring structure, causing ring openingreaction.