Treatment of xanthate flotation reagent wastewater with La/NaTaO3 composite photocatalyst: Synthesis, degradation and mechanism study

As one of flotation reagents in mineral beneficiation process, xanthate is widely used in mining development activities. At the same time, it also caused the production and discharge of a large number of mineral processing reagent wastewater containing xanthate. Photocatalytic technology is a clean and efficient treatment method for this kind of wastewater. However, the previous research on photocatalytic treatment of wastewater containing xanthate mostly focused on how to improve the photocatalytic treatment effect. The structural characteristics and toxicological analysis of various product after xanthate molecular degradation in photocatalytic treatment are still slightly lacking yet. Therefore, in this study, firstly, lanthanum-doped sodium tantalate composite photocatalytic material was prepared, and its preparation process was optimized to improve its photocatalytic performance. On this basis, the molecular degradation mechanism of xanthate and the molecular toxicity analysis of the products in the process of photocatalytic treatment of synthetic wastewater containing three common xanthate components including Sodium ethyl xanthate, Sodium isopropyl xanthate and Sodium butyl xanthate were studied. The results show that the optimum hydrothermal reaction temperature and reaction time for preparing la-doped NaTaO3 composite photocatalytic materials are 160 °C and 14 h, respectively. Under these conditions, the composite with the best photocatalytic performance can be obtained when the doping ratio of La is 6 %. The composite catalytic material was used to treat three kinds of xanthate synthetic wastewater. According to the results of experiment and product mass spectrometry analysis, it is known that all three xanthates are oxidized to be peroxyxanthates, and then the peroxyxanthates are catalytically degraded into inorganic small molecules such as H2O and CO2. The toxicity analysis shows that the toxicities of the product molecules after degradation of the three xanthates are obviously lower than the original substances.