Magnetically Recoverable Ag-TiO₂ Photocatalyst/TiO₂@ Bacillus Research On Treatment Of Xanthate Wastewater

The butyl xanthate(xanthate)present in the mineral processing wastewater seriously harms the ecological environment around the mine,and its treatment is imminent.At present,the treatment of xanthate wastewater at home and abroad mainly includes physical,chemical,photocatalytic,and microbiological methods.Compared with other methods,the photocatalytic method and the microbial method have the advantages of low cost,large processing capacity,and simple process.Because TiO₂ has the special properties of stable chemical properties and good light corrosion resistance,it is often used as a photocatalyst,but its low utilization rate of visible light and difficulty in recycling have always been the root causes of poor wastewater treatment effects and high costs.Therefore,modifying TiO₂ and supporting it on a carrier that is easy to recycle helps to improve the photocatalytic performance and recycling rate.This study improved the photocatalytic performance of TiO₂ by means of modified loading and microbial methods,thereby effectively improving the wastewater treatment capacity.Fly ash magnetic beads(FAMB)are obtained by magnetic separation and separation from fly ash.In addition to the characteristics of fly ash,they also have magnetic characteristics and are easy to recycle.After modification,they can be used as ideal carriers and adsorption materials.In this study,fly ash magnetic beads were magnetically separated from fly ash,and were treated with 2.5 mol/L Na OH in a 60?water bath for 24 h.After cleaning,they were used as carriers to prepare Ag-TiO₂-FAMB photocatalyst by sol-gel method;The effects of photocatalyst dosage,initial p H value of wastewater,initial concentration of xanthate,light intensity and other conditions on the degradation of xanthate and the kinetic law were respectively explored;XRD,SEM,EDS,VSM,UV-vis diffuse reflection were used to characterize the samples in the test;Determine the active species that play a role in the photodegradation of xanthate by the Ag-TiO₂-FAMB photocatalyst through the free radical quenching test;The degradation mechanism of Ag-TiO₂-FAMB photocatalyst photodegradation of xanthate was explored by UV full spectrum scanning and ion chromatography.The test results of Ag-TiO₂-FAMB photocatalyst photodegradation of xanthate wastewater show that the synthesized Ag-TiO₂ is scaly and uniformly supported on the surface of fly ash magnetic beads;The response of the photocatalyst to visible light shifted to 475 nm;The amount of photocatalyst,the initial p H value of wastewater,the initial concentration of xanthate,and the intensity of light.The photodegradation process of xanthate conforms to the pseudo-first-order kinetic equation,and the optimal conditions are 3.0 g/L,p H=5.0,10 mg/L,and 250W,respectively.Under the best test conditions,the degradation rate of xanthate reaches 98.5%after 30 h of light;The photocatalyst recovered by an external magnetic field was used repeatedly for 5 times under the condition of 30 h of light,and the degradation rate of xanthate remained above 83.8%;In the process of photocatalytic degradation of xanthate,superoxide radical(·O₂^-)is the main active species.Although the microbiological method has certain advantages,it has the disadvantage of a long treatment cycle.Microorganisms can provide abundant template resources for the synthesis of various materials.If they are used to synthesize TiO₂ by mineralization,together with the photocatalysis of TiO₂ and the assimilation of microorganisms,the wastewater treatment time can be effectively shortened and the treatment effect can be improved.In this study,butyl titanate was used as a base to synthesize TiO₂@Bacillus using Bacillus,and the conditions of TiO₂@Bacillus bacteria liquid concentration,butyl titanate dosage,initial concentration of xanthate,initial p H value of wastewater,light intensity and other conditions were respectively explored Influence on the degradation of xanthate and its kinetics;In the experiment,SEM,EDS,XRD,FT-IR were used to characterize the samples;The degradation mechanism of TiO₂@Bacillus photodegradation of xanthate was explored by UV full spectrum scanning and ion chromatography.The results of the photodegradation of xanthate waste water by TiO₂@Bacillus bacteria showed that:TiO₂@Bacillus mineralized synthetic TiO₂ is amorphous;The concentration of TiO₂@Bacillus bacteria solution,the dosage of butyl titanate,the initial concentration of xanthate,and the initial p H value of wastewater conform to the pseudo-first-order kinetic equation in the process of photocatalytic degradation of xanthate.The optimal conditions are90 m L/L?150?L/L?10 mg/L?p H=8.0,respectively.Under the above optimal conditions and light intensity of 250 W,the degradation rate of xanthate was 96.3%after 72 h of illumination;In the process of photodegradation of xanthate by TiO₂@Bacillus,the effect of each part is as follows:assimilation>TiO₂ photocatalysis>adsorption.Both Ag-TiO₂-FAMB photocatalyst and TiO₂@Bacillus can effectively degrade xanthate wastewater.The S element in xanthate transforms SO₄^2-in the photodegradation process,and the xanthate is finally degraded into CO₂,H₂O,SO^2- and other small molecules.