Preparation,Visible Light Photocatalytic Properties And Biotoxicity Of ZnS-In₂S₃

ZnS-In2S3 composite photocatalysts with special morphology,strong adsorption properties and low biotoxicity were prepared by hydrothermal method under mild conditions.The disadvantages of single material ZnS which can not respond to visible light and potential biotoxicity and the high cost of indium source for single material In2S3 were solved.Using tetracycline which caused serious environmental pollution as a target pollutant,the photocatalytic performance of ZnS-In2S3 was discussed.The toxicity of ZnS-In2S3 to normal human liver cells was studied by MTT colorimetry.The main results were as follows:1.A series of Zn3(1-x)S3(1-x)-In2xS3x composite photocatalysts with different x values(x=0,0.1,0.2,0.3～1.0)were prepared.The optimum preparation parameters were determined,such as the value of x(0.3),the hydrothermal temperature(80℃)and the hydrothermal time(12 h).2.The performance of ZnS-In2S3 was characterized by BET,XRD,SEM,TEM,ICP,XPS and UV-Vis DRS.The results demonstrated that the specific surface area of ZnS-In2S3 gradually enlarged with the increase of indium content.The composite with the size of 1-3um displays the spherical structure,which formed by self-assembly of In2S3 nanofibers or nanosheets is the main body,and the ZnS particles with a diameter of 3 0nm are embeded In2S3.The actual value of Zn and In content ratio of composite is close to the theoretical value of x(Zn3(1-x)S3(1-x)-In2xS3x).ZnS only responds to ultraviolet light,moreover,the absorption edge of the composite occurs red-shifted significantly with the introduction of In3+.3.ZnS-In2S3 exhibited a good effect on the removal of tetracycline,and the optimum test conditions are established,which the initial concentration of tetracycline was 30mg/L,the dosage of catalyst was 1.5g/L,the initial pH value was 7.The removal efficiency of ZnS-In2S3 to tetracycline reached 95.73%at the optimum experimental parameters under visible light for 40min,and accordingly the removal efficiency of TOC came up to 82.75%,and the removal efficiency was close to 100%in natural light.4.The toxic effect of ZnS and ZnS-In2S3 on L-02 cells was detected by MTT.The inhibitory effect of L-O2 was dependent on dose and time.ZnS had an obvious inhibitory effect on L-O2,while ZnS-In2S3 had a low inhibitory effect.In this paper,the mechanism of the biological toxicity of ZnS-In2S3 to cells is speculated,and it may be illumination that produces reactive oxygen species(h+,·O2-,·OH,·OOH,H2O2)have an damage to lipid,protein,nucleic acid and so on,or Zn2+ released from ZnS-In2S3 is connected with the biological macromolecular active sites or electron donors,Thus,the normal physiological metabolism of cells is disrupted.