Preparation Of Manganese Oxide Composites And Its Application In Wastewater Treatment

Sulfide found in wastewaters and industrial off-gases is a toxic and highly corrosive pollutant.The air-cathode fuel cell has great potential for simultaneous elemental sulfur(S0)and electricity recoveries from sulfide.Here,manganese oxide(MnOx)is in-situ synthesized on graphite felt(GF)surface in a solvothermal system at different ethanol/water(E/W)volume ratios,and the prepared MnOx/GF composites are used as the anodes of air-cathode fuel cell for spontaneous sulfide electrochemical oxidation.The performance of these MnOx/GF composite anodes is comprehensively evaluated in term of sulfide removal,sulfur recovery and electricity production efficiencies.The results show that the manganese oxide loading on the GF presents as MnO2 at E/V ratio of 0/10.When the E/W ratiois greater than 3/7,the obtained manganese oxides are all Mn3O4 and its particle size and loading on the GF decrease with the increase of ethanol concentration.The Mn3O4/GF composite prepared at E/W ratio of 3/7 has a great potential in catalyzing the electrochemical oxidation of sulfide in the air-cathode fuel cell.Compared with GF,the Mn3O4/GF composite anode shortens the time for complete sulfide oxidation from 120 h to 60 h.Meanwhile,the sulfur recovery efficiency and coulombic efficiency are as high as 78.4%and 71.5%,respectively.MnOx/Graphite felt composite electrode prepared by solvothermal method was allied with cathodic electro-Fenton and anodic oxidation to degrade methylene blue(MB).Taking decolorization rate and TOC as the evaluating indicator,the degradation performance of cathodic elctro-Fenton method,anodic oxidation method and combined method on MB were analyzed.It could be seen that the higher valence of manganese oxide supported on the carbon felt,the better the degradation effect of MB performed.The order of the activity is MnO2/GF>Mn3O4/GF>MnO/GF.Five successive batch cycles decolorization of MB show the good reproducibility of MnO2/GF electrode.In addition,MnOx/GF composites as anode play a major role in the degradation of MB.The low energy cost and application of low-priced carbonaceous anode endow the oxidation process with great potential for use in the remediation of MB.