Study On Photoelectrocatalytic Inactivation Of Escherichia Coli By Modified MoS₂ Electrode

Photoelectrocatalytic oxidation technology?PEC?has attracted attention as a new type of disinfection technology.Photoelectrocatalytic oxidation technology is an electric-assisted photocatalytic technology and belongs to the category of advanced oxidation technology.The technique promotes the separation of photogenerated electrons and holes by applying an external bias to the material,improves the quantum efficiency of photocatalysis,and accelerates the inactivation of pathogenic microorganisms.Nano-MoS₂ electrodes were successfully prepared by hydrothermal method.The electrodes were modified by high temperature air oxidation.The effects of different thermal oxidation temperatures on the properties of the materials were investigated.The physicochemical properties of the modified MoS₂ electrode were analyzed by multi-scale characterization methods such as absorbance,crystal form,microstructure,crystal phase,elemental composition and valence state.The photoelectrochemical properties of the material?photocurrent change,linear sweep voltammetry,and electrochemical impedance?were tested.The results show that the thermally oxidized modified MoS₂ electrode material exhibits strong photocurrent effect,higher carrier mobility and photoelectric performance under visible light?400?800 nm?irradiation at 250 ?.E.coli is selected as the indicator microorganism for testing the bactericidal effect.The effects of material toxicity,illumination,applied bias voltage,electrolyte concentration and initial concentration of bacteria solution on photoelectrocatalytic bactericidal effect were investigated.The mechanism of photoelectrocatalytic sterilization was further studied.The test results showed that the bactericidal rate of E.coli solution with an initial concentration of 106CFU/m L could reach 99.9999% after 0.1 mol/L sodium chloride as the electrolyte under 0.5 V external bias.The effects of free radical trapping agent,dissolved oxygen concentration and electrolyte type on sterilization showed that the photoelectrocatalytic inactivation of Escherichia coli by modified MoS₂ electrode was completed by a variety of free radicals and could destroy the cell structure of E.coli.An opto-electrochemical reactor for use with solar cells has been developed which has the characteristics of continuous operation,larger photoanode area and more water treatment.The optimal parameters for reactor operation were determined by examining the effects of bias voltage,cathode position,bacterialspecies,light intensity,and coexisting pollutants on the sterilization effect.The applied bias voltage was 1.5 V,sodium chloride concentration was 0.1 mol/L,and light intensity was 74 m W/cm²,the electrode spacing is 5 cm,and the initial concentration of 10⁶ CFU/m L of the E.coli bacterial solution reacts for 6 h under the above conditions to achieve an inactivation rate of 99.99%.The stability of the electrode material after sterilization was analyzed by XPS,XRD and Raman characterization.