Study On Photocatalytic Degradation Of Xanthate In Bi₂o₃ Suspension Under Visible Light

Xanthate is an organic flotation reagent, which is commonly used in the flotation of non-ferrous metal sulfide minerals. This paper drawed lessons from the advanced techniques (photocatalytic oxidation) in water processing to study the degradation effect and regulation of xanthate.In this paper, Bi2O3 powders were prepared by coprecipitation and characterized by X-ray Diffraction(XRD), Particle Size analysis and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). The effect of heat treatment on the crystalline structure,grain size and photocatalytic activity of Bi2O3 powders were examined. The results show that Bi2O3 powders calcinated at 500℃has the best photocatalytic activity.It can effectively degrade xanthate under visible light, and this process has advantages of mild reaction conditions, convenient operation procedure, and less energy consumption.The photocatalytic degradation behaviors of butylxanthate in Bi2O3 suspension under visible light has been studied in this paper. Some influencing factors of degradation such as illumination time,the addition of Bi2O3,pH value of solution and butylxanthate concentration were investigated under visible light(λ≥420nm) irradiation.The results indicated that the illumination time and the dosage of Bi2O3 on the degradation of butylxanthate were most significant. The degradation rate of xanthate increase with the increase of illumination time, but the rate did not changed significantly after 180min.The dosage of Bi2O3 can also produce certain effect on the degradation rate of butylxanthate,and the optimum dose was 1.67g/L.The initial concentration of the aqueous of butylxanthate was also an important factor.The photodegradation efficiencies fall with the increase of the initial concentration of butylxanthate.The rate of xanthate degradation did not changed obviously with the different value of pH,and the degradation rates were more than 94%.The proper reaction condition was decided by the experiment.When the concentration of the aqueous of butylxanthate was 50mg/L at the initial pH7.0,the dosage of Bi2O3 was 1.67g/L,the degradation rate of butylxanthate reached 98.32% and the removal rate of CODCr can be higher than 82% after 180min. Kinetic researches indicated that the degradation process of butylxanthate obeyed the L-H model.The rate reaction constant and the Langmuir adsorption constant were 2.897mg/(L-min) and 4.272×10-2L/mg respectively.The mechanisms on the photocatalytic degradation of butylxanthate by catalyst Bi2O3 were analyzed by infrared analysis(IR) and ultraviolet-vis light analysis (UV-Vis).The results of IR showed that the degradation pathway of xanthate was adsorbed and then was degraded by Bi2O3.The results of UV wavelength scan showed that a small amount of mediate product was generated in the process of butylxanthate degradation.