Treatment Of Diesel Oil Wastewater By Cathodic Modified Electric Fenton Process

Oily wastewater is recognized as industrial wastewater with high treatment difficulty.With the development of petrochemical industry,a large number of wastewater that can not meet the discharge requirements enter the water body.Traditional biological methods for the treatment of such wastewater are inefficient and ineffective.The technology still used in most parts of China can not meet the current and future environmental requirements.Scientists have done a lot of research experiments on this.Among them,the electro-Fenton method has attracted a lot of attention because of its high efficiency and fast reaction.In this paper,the electro-Fenton method was used to treat simulated diesel wastewater.Graphite electrode was chosen as cathode and iron electrode as anode.The optimal reaction conditions were investigated.The results showed that when the concentration of oily wastewater was 100 mg/L-1,pH=3,electrolytic voltage was 12 V,Na2SO4 concentration was 20 g/L and reaction time was 1 h.Through orthogonal experiment,the influence degree of each factor is as follows:initial oil concentration>pH value>electrolytic voltage>electrolyte concentration.Under the optimum experimental conditions,oil removal rate can reach 72%,COD removal rate can reach 70.13%.On the basis of graphite electrode and inspired by hydrogen peroxide fuel cell,nitric acid,phosphoric acid and ammonia hydrogen phosphate solution were selected to modify the graphite electrode in order to improve the hydrogen peroxide production and current efficiency of the electrode.Under the optimum reaction conditions,the yield of hydrogen peroxide of C(NP)electrode modified by 0.3mol·L-1HNO3 and H3PO4 mixed solution increased the most.Compared with the unmodified graphite gas diffusion electrode,the yield of hydrogen peroxide increased by 40.2%in 60 minutes.The graphite electrode had better treatment effect in treating oily wastewater.The reaction was carried out at 60m.The oil removal rate at in is 79.6%,which is about 10%higher than that at conventional graphite electrodes.The COD removal rate is 76.3%,which is about 6%higher than that of the unmodified electrode.At the same time,the modified process was preliminarily studied.Under the same experimental conditions,when the mass ratio of graphite to PTFE was 2:1,the catalytic activity of the electrode for the reduction of dissolved oxygen to produce hydrogen peroxide was the highest.The catalytic activity of the electrode for the reduction of oxygen to produce hydrogen peroxide can be greatly improved by calcining the electrode at 350?.At the same time,the physical strength of the electrodes increased significantly.The first-order reaction kinetics equation of treating simulated oily wastewater by graphite cathode electro-Fenton process is:In(C0/Ct)=0.0171t+0.0091,(the rate constant is 0.0171min-1,and the linear correlation coefficient is R2=0.9719).It conforms to the first order reaction kinetics model.The first-order reaction kinetics equation of treating simulated oily wastewater by electro-Fenton process with C(NP)modified cathode is ln(C0/Ct)=0.0184t+0.4118,(the rate constant is 0.0184min-1,and the linear correlation coefficient is R2=0.9187).It conforms to the first order reaction kinetics model.