Research On O₃/nano-TiO₂ Photocatalytic Degradation Of Sodium Dodecylbenzene Sulfonate

The radioactive washing wastewater which contains organic substances is characterized as low-level radioactivity and large volume.The traditional physical methods for the treatment of this kind of low-level radioactive washing wastewater will generate large amount of secondary radioactive waste,and the existing chemical methods have disadvantages of poor efficiency.In this paper,a new technology of photocatalytic oxidation based on O3/nano-TiO2 was used to degrade the typical surfactant sodium dodecyl benzene sulfonate(SDBS).The effects of rediaoctivity on the degradation of nuclear washing wastewater containing SDBS were investigated by adding splintered nuclides 90Sr and 137Cs+.Additionally,the degradation and mineralization mechanism of this technology were further discussed.In the experiment of disposal of SDBS by photocatalytic oxidation based on O3/nano-TiO2,the effects of the initial concentration of SDBS solution,pH,illumination time,ozone input,and splintered nuclides Sr2+and Cs+on the degradation of SDBS were studied.and the best experimental conditions for degrading of SDBS(SDBS removal rate of 99.95%)was obtained.The conditions were as follows:solution concentration was 300 mg/L,pH=9.0,UV power was 42 W,O3 flow was 0.3 L/min,reaction temperature was 20?.Furthermore,we found that the addition of higher activity splice nuclides 90Sr and 137Cs+has little influence on the removal rate CODand SDBS.The structures and compositions of the intermediate and the final products were characterized by Fourier transform infrared(FT-IR),UV—visible spectrum(UV-vis),Thermogravimetric analysis(TGA).Powder X-ray diffraction(XRD).X-ray photoelectron spectroscopy(XPS),X-ray diffraction fluorescence(XRF),elemental analysis and mass spectrometry(MS).And the degradation mechanism of SDBS through photocatalytic oxidation based on O3/nano-TiO2 was analysized by the quantum chemical density functional theory.The intermediate products included 4-dodecyl-6hydroxyl cycclohexanol-2,4-diene-1 sodium(molecular weight 366).4-dodecyl ring has-3,5-diene-1,2-glycol(molecular weight 280),and(2Z,4Z)-3--dodecyl ring has-2,4diene dicarboxylic acid(molecular weight 310).The final products included extremely small amount of SDBS and the inorganic salt,such as sodium bicarbonate and sodium dithionite.The degradation and mineralization mechanisms of the present technology were given.In conclusion,a new technology of photocatalytic oxidation based on O3/nano-TiO2 was proven to be successful in degrading the typical surfactant sodium dodecyl benzene sulfonate(SDBS).This technology brought not only high degradation rate but also high COD removal rate,indicating its big potential in the treatment of nuclear radioactive washing wastewater.To remove surfactant SDBS in radioactive washing wastewater,the photocatalytic technology based on O3/nano-T1O2 has not been reported utill now.