Activation Of Peroxymonosulfate By Iron-saturated Montmorillonite For Elimination Of Atrazine

Advanced oxidation process（AOPs）shows excellent degradation ability in the field of refractory pollutants in water environment.Due to the stronger redox potential and high selectivity,sulfate radical（SO4·^-）AOPs（SR-AOPs）based on activated peroxymonosulfate（HSO₅^-,PMS）has received more and more attention.Various Fe-based catalysts are widely used for PMS activation due to their environmental friendliness and low cost.However,it is only suitable for acid pH value,slow conversion rate of Fe（III）to Fe（II）,and excessive leakage of iron ions limit its wide application.The above disadvantages can be effectively avoided by fixing the iron-based catalyst to the carrier material.In this experiment,Fe-saturated montmorillonite（Fe-MMT）was obtained by loading Fe³⁺onto the surface and lamellar space with sodium montmorillonite（MMT）as the carrier material.Use it as a catalyst to activate PMS.Compared with MMT,Fe-MMT has higher iron content,larger specific surface area and pore volume.In addition,the introduction of iron ions changes the ordered interlayer structure of natural MMT,and the fe-mmt structure is more loose and the interlayer spacing is enlarged.The adsorption capacity of the two materials to the target contaminant（ATZ）and their ability to activate PMS were investigated.It was found that Fe-MMT could not only effectively activate PMS to degrade ATZ,but also effectively adsorb ATZ.In the process of adsorption and catalysis,Fe-MMT shows good reusable performance,accompanied by a very small amount of iron ion leakage.The adsorption and catalytic properties of Fe-MMT are greatly affected by the amount of Fe-MMT the initial ATZ concentration and the initial pH value of the system.In the range of 0.1-1.0 mm,the PMS dosage has no significant influence on the oxidation efficiency of the system.The increase of ion strength of the system or the presence of some inorganic anions will lead to the decrease of adsorption sites and catalytic sites in Fe-MMT,leading to the weakening of adsorption and catalytic properties.However,the presence of Cl^-and low concentration of HCO₃^-would significantly increase the degradation efficiency of ATZ.Natural macromolecular organic humic acid has little effect on the adsorption and oxidation properties of the system.Under the background of natural water,Fe-MMT/PMS system can still effectively degrade ATZ,but the adsorption performance of Fe-MMT is greatly reduced.Fe-MMT/PMS system can effectively degrade different types of organic pollutants,but Fe-MMT only shows adsorption effect on some organic pollutants.Finally,the adsorption mechanism of Fe-MMT on ATZ and the activation mechanism of PMS were proposed through experiments.Fe-MMT mainly adsorbs ATZ by hydrogen bond formed by hydration around interlayer Fe³⁺.It was inferred from the experiment that the mechanism of electron accelerated transfer between layers of montmorillonite accelerated the recycling and regeneration between Fe³⁺and Fe²⁺,thereby activating PMS to produce sulfate radical and hydroxyl radical degradation ATZ.