Photocatalytic Reduction Reaction And Kinetics Of Cr??? Removal By Fe³⁺/TiO₂

In recent years,with the development of electroplating,leather making and textile industry,a great deal of poisonous and harmful chromium containing wastewater has been produced.The toxic Cr(?)in chromium containing wastewater was 100 times higher than that of Cr(?).Wastewater containing Cr(VI)was harmful to people's health.It can cause mutation,teratogenicity and carcinogenicity in serious case.Therefore,it was a hot research to find a cheap and efficient method for the treatment of wastewater containing Cr(?).Based on this,Fe3+/TiO2 was used as photocatalyst to study photocatalytic degradation of Cr(VI)by Fe3+/TiO2 degradation.It provided a theoretical reference and technical support for the removal of Cr(VI)in wastewater.Firstly,the catalyst Fe3+/TiO2 was prepared by ultrasonic impregnation.The preparation conditions of catalyst Fe3+/TiO2(concentration of Fe3+,calcination time and calcination temperature)were studied.Characterization and analysis of the structure and properties of the catalyst;Then,the effects of Fe3+/TiO2 on the photocatalytic reduction of Cr(VI)were studied.The effects of reaction time,pH value of solution,initial concentration of Cr(VI),dosage of Fe3+/TiO2 and hole scavenger,Finally,the kinetics of the photocatalytic reduction of Cr(VI)by Fe3+/TiO2 was calculated,and the apparent reaction rate constant of the photocatalytic reduction of Cr(VI)by Fe3+/TiO2 was calculated.The results showed that the optimum preparation conditions of catalyst Fe3+/TiO2 were as follows:the concentration of Fe3+ in the impregnating solution was 0.75 g/L,the calcination time was 150 min,and the calcination temperature was 450 ?.X-ray diffraction analysis showed that Fe3+/TiO2 did not show obvious crystal structure change,and Fe3+ supported on the catalyst surface.The particle size analysis showed that the size of the Fe3+/TiO2 particle size did not change significantly.The optimum experimental conditions for photocatalytic degradation of Cr(?)by Fe3+/TiO2 degradation were studied.Solution pH = 5,initial concentration of Cr(?)C0=1 mg/L,Lthe dosage of Fe3+/TiO2 was 2 g/L,and the amount of methanol was 10 mmol/L.The analysis showed that the pH value of the solution showed a slowly increasing trend in the reaction process,while the amount of Fe3+ precipitation in water was less.The results show that the photocatalytic reduction efficiency of Fe3+/TiO2 is higher than that of TiO2,and the amount of catalyst is reduced.The optimum pH is from 1 to 5,which is in accordance with the idea of low carbon energy saving.Finally,the initial reaction rate constant of Cr(?)the dosage of Fe3+/TiO2 and the pH value of the solution on the photocatalytic reduction of Cr(VI)by Fe3+/TiO2 were studied by the established reaction kinetics model.The apparent response rate constant is obtained.(1)when the dosage of Fe3+/TiO2 catalyst was less than 2 g/L,the pH value of the solution was less than 5.Apparent total reaction rate constant:k = 5.7018 × 10-6 C0-0.053 n0.967CH+-0.045(2)when the dosage of Fe3+/TiO2 catalyst was less than 2 g/L,the pH value of the solution was more than 5.Apparent total reaction rate constant:k = 1.3 8159 × 10-4 C0-0.053 n0.967 CH+0.150(3)when the dosage of Fe3+/TiO2 catalyst was more than 2 g/L,the pH value of the solution was less than 5.Apparent total reaction rate constant:k = 1.29688 ×10-4C0-0.053n-0.119CH+-0.045(4)when the dosage of Fe3+/TiO2 catalyst was more than 2 g/L,the pH value of the solution was more than 5.Apparent total reaction rate constant:k=3.14244 ×10-4C0-0.053nn-0.119CH+0.150...