Preparation And Photocatalytic Properties Of Hollow Spherical Cadmium Sulfide Composites

Sulfide ore resources are essential basic raw materials in the process of social development and economic operation.The development of mineral resources has not only created huge economic benefits,but also brought certain impact on the environment.Among them,the wastewater of mineral processing is the main factor causing the deterioration of mine environment.The residual collectors in the wastewater have a long-term impact on the soil,animals and plants around the mine,and ultimately endanger human health.Xanthate is the most widely used collector in the flotation process of sulfide ores.As a new wastewater treatment technology developed in the 1980s,photocatalysis is considered to be an ideal method for treating mineral processing wastewater due to its advantages of environmental protection,high efficiency and no secondary pollution.Cadmium sulfide（Cd S）is a common semiconductor material,which has been widely studied in the field of photocatalysis due to its simple preparation method,excellent photocatalytic performance and availability of visible light.However,the disadvantages of small specific surface areas,rapid recombination of photogenerated electron-hole pairs and easy to be photocorroded seriously limit the application of Cd S.In this paper,we prepared Cd S hollow spheres by template method.Furthermore,to improve the photocatalytic performance of Cd S hollow spheres we prepared Cd S/PANI/MWCNTs and Cd S/CN composite photocatalysts by doping and constructing heterojunction,respectively.The photocatalysts were used to treat the butyl xanthate（SBX）simulated wastewater,and the photocatalytic degradation performance and mechanism of SBX were also discussed.The research contents and results of this paper are as follows:（1）The Cd S nanoparticles were deposited on the Si O₂microspheres by hydrothermal method,and the Cd S hollow spheres were prepared after the Si O₂was etched in strong alkaline solution.The SEM,TEM and TEM-EDS tests showed that the Cd S hollow spheres were successfully prepared.（2）To increase the active sites of the reaction and inhibit the photocorrosion of Cd S,MWCNTs and PANI were successfully loaded and coated on Cd S hollow spheresl,respectively,then Cd S/PANI/MWCNTs composite photocatalysts were obtained.By changing the wavelength of the simulated light source,it was determined that Cd S/PANI/MWCNTs had the highest catalytic efficiency under ultraviolet light.The photocatalytic degradation experiments of SBX solution were carried out under ultraviolet light to evaluate the photocatalytic performance of Cd S/PANI/MWCNTs.The optimum experimental conditions for SBX solution degradation were obtained by investigating the amount of Cd S/PANI/MWCNTs composite,the amount of MWCNTs doped and the coating time of PANI.The mechanism of photocatalytic degradation of SBX by Cd S/PANI/MWCNTs was discussed based on the performance characterization of the materials.（3）To increase the utilization of visible light,improve the separation of photogenerated carriers and inhibit the photocorrosion of Cd S,Cd S/CN photocatalysts with Z-type heterojunction was prepared by solid dispersion method.Then through its photocatalytic degradation efficiency of SBX under visible light,the optimal ratio of Cd S in Cd S/CN composite photocatalyst was explored.When the catalyst dosage was 35 mg and degrades 100 m L of SBX simulated wastewater with a concentration of 20 mg·L^-1,the photocatalytic efficiency of Cd S/CN heterojunction reached to 99.0%.Meanwhile,the repeatability experiments showed that the Cd S/CN heterojunction had good stability.A series of performance experiments and the possible photocatalytic mechanism of Cd S/CN composite were discussed.