Impact Of The Interaction Between Hematite And Clay On Environmental Fate Of Organic Pollutants

The mineral composition of soil is complex,and the interaction between various minerals jointly determines the fate of pollutants in soil.Among them,the coexistence of clay minerals and hematite has been widely reported.Therefore,based on based on the above findings,Fe₂O₃-HNTs,Fe₂O₃-Kao and Fe₂O₃-Mt were synthesized by co-precipitation method to simulate the interaction of halloysite,kaolinite and montmorillonite.XRD,TEM,XPS,FTIR and sample color were used to show the characterizations of samples.And Methylene blue,phenol,norfloxacin,sulfadiazine sodium,oxytetracycline and 2,4-dichlorophenol were used as probe molecules to study the effect of the interaction between clay minerals and hematite on the adsorption of organic pollutants by clay minerals and the degradation of organic pollutants by activated hydrogen peroxide of hematite.And the influence of this interaction on the environmental fate of organic pollutants was understand.The main research results are as follows:（1）According to XRD,TEM,XPS,FTIR and sample color results,hematite was uniformly dispersed on the surface of clay minerals,which resulting the low crystallinity of hematite.The results of acid solution experiment showed that the effect of halloysite dispersing hematite was the strongest.（2）After loaded hematite,the methylene blue adsorption capacity of halloysite,kaolinite and montmorillonite were slightly less than raw material,which was due to the existence of the hematite hindered the contact between methylene blue and clay minerals surface.But the adsorption characteristics are not changed.Halloysite,kaolinite and montmorillonite before and after loading hematite,the adsorption process of methylene blue were in line with the Langmuir adsorption isotherm and second-order kinetics.（3）The dispersion effect of halloysite on hematite effectively promoted the ability of hematite to activate hydrogen peroxide to degrade methylene blue.The experimental results of influencing factors showed that the dosage is 0.5 g·L-1 and the initial pH value is 3,the removal rate of methylene blue with 1.0 mM could reach 100%at 299 K.In the presence of hematite,the adsorption of Methylene blue by halloysite could also be gradually degraded with increasing time,but the degradation rate was low.EPR characterization,hydroxyl radical quantification and quenching experiments showed that hydroxyl radical was the main active species for degradation in this system.（4）Comparison experiments of adsorption and degradation of other organic pollutants by Fe₂O₃-HNTs further proved that the interaction between hematite and halloysite would hindered the adsorption of organic pollutants by halloysite,and promoted the rate of degradation of organic pollutants by activated hydrogen peroxide of hematite.