Study Of The Treatment Of The Oil-Containing Emulsified Wastewater With The Hierarchical Porous Biomass Carbon-Based Electrode

Oily emulsified wastewater as a special kind of organic wastewater,contains not only a large number of oily substances,but also many kinds of additives such as surfactants,alcohol cosolvents,bacteriostatic agents,antirust agents and so on.It poses a serious threat to the environment and human health.Demulsification is usually the pretreatment stage of wastewater for subsequent wastewater treatment.In this paper,birch biomass carbon-based materials with the advantages of metal doping,good electrical conductivity,graded porous structure and high specific surface area were synthesized by hydrothermal and high temperature carbonization.The material is used as an integral electrode to combine electrochemical technology with adsorption technology for the treatment of various oil-containing emulsified wastewater by electrosorption.The specific research results are as follows:（1）The electrodes were characterized by using SEM,TEM,XRD,XPS,BET and other physical characterization methods.The hierarchical porous and mesoporous nature of the electrode was shown.the specific surface area of 387 m² g^-1 was determined,and the doping Fe and Ni metal elements in trace amounts were displayed.The graphene model(C₅₄H₁₈)and biomass model(C₅₇H₁₆O₈),as well as the electrode models under different acid and alkaline conditions,were also to microscopically analyze the mechanism of electrode emulsion breaking and contaminant removal.（2）Treatment of toluene emulsion wastewater and toluene microemulsion wastewater using biomass carbon-based material electrodes:the demulsification ability of the electrode increases with the enhancement of voltage.When treating the low concentration toluene emulsified wastewater,it can demulsify in 2.0 h at 1.5 V and obtain more than 99%toluene removal rate.Moreover,it can use solar energy to demulsification and remove oil.The demulsification method has the advantages of high efficiency demulsification and oil removal,low energy consumption and clean energy.The electrode can also be used to treat toluene emulsion wastewater stabilized by different types of surfactants as well as toluene microemulsion.Finally,the mechanism of electrode electrosorption for emulsion demulsification and oil removal was demonstrated by experiments,density functional theory calculations.（3）Treatment of emulsified wastewater from cutting fluid in copper processing industry using biomass carbon-based material electrode:it was demonstrated that the demulsification effect of metal-doped electrode（Fe Ni/CW electrode）was much better than that of non-metal-doped electrode（CW electrode）.The presence of metal ions in the wastewater inhibited the demulsification effect,prolonged the emulsion demulsification time,reduced the COD（chemical oxygen demand）removal rate,increased the SEC（specific energy consumption）,etc.,and the degree of inhibition was greater for Zn²⁺than that for Cu²⁺.Decreasing the demulsification voltage and increasing the concentration of oil phase would increase the demulsification time and decrease the removal rate of metal ions.The water hardness(i.e.,Ca²⁺concentration)of the cutting fluid dilution water would reduce the emulsion demulsification effect.However,the presence of Cu²⁺enhanced the demulsification effect of Ca²⁺containing wastewater,and the Fe Ni/CW electrode using electrolytic Cu Cl₂ solution could promote the demulsification effect of emulsified wastewater containing Ca²⁺.It is demonstrated that the electrode doped with copper can promote the Ca²⁺containing wastewater demulsification.Finally,the mechanism of electrode for emulsion demulsification and oil removal and metal ion removal from cutting fluid wastewater was discussed through experimental and model analysis.（4）Treatment of microemulsion wastewater from cutting fluid in copper processing industry using biomass carbon-based material electrode:the presence of cations will increase the demulsification time and reducing the COD removal rate,etc.,so it cannot achieve the effect of demulsification in a short time,especially hard water inhibits demulsification.The demulsification experiments and cyclic voltammetry experiments of microemulsion wastewater showed the mechanism of demulsification and oil removal almost exactly similar to its cutting fluid emulsion wastewater,with the difference that the electrode can remove the co-solvent that stabilizes the microemulsion by adsorption and redox,and increase the instability of microemulsion to promote demulsification.