Study On The Preparation Of Porous Ti/TiO₂/CdS-CNT/C₃N₄ Photoelectrode And Photoelectric Catalytic Degradation Of Tetracycline

In recent years,domestic and international scholars researched about modifying porous Ti/TiO₂ photoelectrode with various methods.At the same time,they combined the electric catalytic technology with other techniques to deal with organic wastewater.Although,great achievements had been made about the photo-electrocatalytic degradation of the medical wastewater using Ti/TiO₂ photoelectrode,it can be only excitated by less than 387 nm wavelength ultraviolet,which just absorbed small amounts of natural light.This wok mainly studies the modification,optimization of Ti/TiO₂ photoelectrode mainly using CdS,carbon nanotubes?CNT?and C₃N₄ and the photoelectric catalysis performance testing with some characterization methods.It is difficult to deal with the pharmaceutical waste-water such as antibiotic waste-water in industrial treatment,or the treatment effeciency was lower.Because of this,this paper set tetracycline as target pollutants in order to research influence factors and the best drgradation conditions of tetracyclines.Firstly,in terms of the electrode preparation,the porous Ti/TiO₂/CdS-CNT/C₃N₄photoelectrode were successfully fabricated via anodic oxidation method,chemical electrodeposition and dip-coating method,respectively.Secondly,in terms of characterization,the morphology,crystal structure and elements of the photoelectrodes were characterized by scanning electron microscopy?SEM?,X-ray diffraction?XRD?,energy-dispersive spectroscopy?EDS?and X-ray photoelectron spectroscopy?XPS?respectively.The cyclic voltammetry?CV?,electrochemical impedance spectroscopy?EIS?,linear sweep voltammograms curves?LSV?,mott-schottky?MS?and chronoamperometric curves were applied to research the oxidation-reduction quality,resistance,carriers concentration and photocurrent stability respectively.Addtionally,the service lifetime of electrodes were measured in accelerated life test.The photo-electrocatalytic?PEC?performance of the photoelectrodes were evaluated in the degradation experiment of methylene blue.Compared with the Ti/TiO₂ and Ti/TiO₂/CdS-CNT electrode,the Ti/TiO₂/CdS-CNT/C₃N₄ electrode possesses smaller grain size on the surface,more uniform crystal morphology,lower resistance,bigger photocurrent density,oxygen evolution potential and photogennerated carriers concentration and performed higher PEC activity.Moreover,the genneration of much holes and·OH can promote the PEC degradation of organic pollutants.Particularly,electrode with C₃N₄ can further increase·OH generation capacity in degradation process.Finally,in terms of the practical application,Ti/TiO₂/CdS-CNT/C₃N₄ electrode was used to treat simulative tetracycline wastewater which was studied in five degradation factors(current density,solution pH,light intensity,initial concentration,concentration of electrolyte.The results showed that when 100 mg/L tetracycline was treated under the conditions of the current density of 10 mA/cm²,105 W/cm² light intensity,solution pH=11,0.06 mol/L Na₂SO₄electrolyte,photo-electrocatalytic degradation of tetracycline will work best.At the same time,the spectral scanning statutory of tetracycline degradation situation within 1 h was analyzed,and the COD removal rate of the tetracycline solution were studied.Results showed that the degradation capacity of tetracycline using Ti/TiO₂/CdS-CNT/C₃N₄ electrode can be more than 90%under the optimized reaction conditions.