Study On The Application Of Bismuth Molybdate In The Removal Of Environmental Pollutants

In this thesis,various Bi2MoO6 nanostructures were prepared by different methods,including nanoparticles,hollow nanospheres and nanosheets.Combined with XRD,SEM,TEM and UV-vis DRS,the photoelectric chemical,catalytic or adsorption properties of the samples were studied.The application of Bi2MoO6 material in removing environmental pollutants was studied.Finally,the internal mechanism of Bi2MoO6 material was analyzed.The specific research content is as follows:A highly efficient and recyclable fractional microsphere Bi2MoO6(BMO)adsorbent was synthesized by solvothermal method using cetyltrimethyl ammonium bromide(CTAB)as surfactant.Taking methylene blue(MB)as the target pollutant,the adsorption kinetics,adsorption isothermal and adsorption thermodynamics of MB on BMO were systematically investigated.The adsorption mechanism of MB on BMO was chemical adsorption.When MB was at low concentration,it was mainly diffused controlled adsorption,and when MB was at high concentration,it was saturated monomolecular layer adsorption.And the adsorption process is spontaneous and random increase.The adsorption mechanism was studied by XRD,FTIR,XPS and UV-vis DRS.It was found that BMO layered microspheres synthesized by solvothermal method not only have rough surfaces but also abundant surface defects,such as surface vacancy defects,surface dangling bonds and non-moving charges.These surface defects can be equivalent to negative surface charges,which can enhance the adsorption of dyes such as MB by BMO through electrostatic interaction.The optimal adsorption conditions were predicted by Box-Behnken Design(BBD)in Response surface method(RSM),ph=2.56,T=10℃,C BMO=0.8 g L-1In this work,we have elucidated the pH-induced structural evolution of Bi2MoO6 photocatalyst based on a hydrothermal synthesis route.With increasing the pH value of precursor solution,it brings about the synthesis of pure Bi2MoO6 at pH 2-5,Bi2MoO6-Bi4MoO9 mixture at pH 7-9,pure Bi4MoO9 at pH 11 and pure α-Bi2O3 at pH 13.The photocatalytic performances between the samples were compared via the degradation of methylene blue(MB)under irradiation of simulated sunlight.The Bi2MoO6 sample synthesized at pH 2 was shown to exhibit the highest photodegradation performance among the samples.The underlying photocatalytic mechanism and degradation pathways of MB were systematically analyzed.In addition,the photocatalytic activity of Bi2MoO6 photocatalyst in different acid-base environments was tested,and the study showed that OH-was conducive to the formation of active species.The degradation of 16 organic pollutants showed that Bi2MoO6 could degrade most of the organic pollutants,which expanded the application of Bi2MoO6 photocatalyst in real life.Bi2MoO6 nanosheets were derived via a hydrothermal synthesis route.the photocatalytic activity of photocatalysts was improved by stress-induced polarization.Simulated sunlight,ultrasonic and both of them were used to drive the photocatalysis,piezocatalysis and piezo-photocatalysis to degradation of MB,MV,EY,FA,RhB and TC.The results showed that the degradation efficiency of Bi2MoO6 nanosheets on various organic dyes and antibiotics was significantly higher than that of photocatalysis or piezoelectric catalysis alone.Combining with XRD,FTIR,XPS and other characterization methods,it is found that periodic polarization makes electrons and holes move in opposite directions,which inhibits the recombination of electron-hole pairs.In addition,taking a typical organic dye methylene blue(MB)as an example,the effects of various factors on its degradation efficiency,possible degradation pathways,and toxicity evaluation of degradation by-products were studied.The application of Bi2MoO6 in removing environmental pollutants has been enhanced.