Abstract: In order to degrade the flotation agent ethyl xanthate remaining in the beneficiation wastewater， a composite photocatalytic material Co-g-C3N4/La-TiO2 was prepared by the sol-gel method. The morphology， crystal structure， photochemical properties and surface chemical properties of the samples were characterized by SEM， XRD， UV-Vis， PL and XPS spectrum.The effects of catalyst dosage， simulated wastewater pH， initial concentration of ethyl xanthate and time on the photocatalytic effect were studied. Free radical capture experiments have also been carried out to determine the active groups that play a role in the photocatalysis process. The results showed that La and Co in Co-g-C3N4/La-TiO2 exist in the form of La3+ and Co2+. The band gap decreases and the absorption band edge was red-shifted， thus the photocatalytic efficiency is high. Under the conditions of catalyst dosage of 1 g/L， ethyl xanthate concentration of 60 mg/L， and pH of 10， the degradation rate of ethyl xanthate reached 99.1% after 60 minutes of photocatalysis reaction. Holes （h+）， hydroxyl radicals （·OH） and superoxide radicals （·O2-） all have a great contribution to the degradation of ethyl xanthate during the process of photocatalytic oxidative， and the degree of contribution is ranked as ·OH＞h+>·O2-.

Key words: ethyl xanthate, titanium dioxide, graphite phase carbon nitride, metal doping, photocatalytic oxidation