| As a kind of aminoglycoside antibiotics,gentamicin was widely used in the inhibition of bacterial infections.However,with the abuse of gentamicin,more and more gentamicin in the form of the parent or its metabolites were discharged into the environment,causing serious environmental pollution and potential health threats.Montmorillonite has been widely used in the field of environmental protection because of its excellent adsorbability and ion exchange properties.However,it is still a blank in the application of the control of aminoglycoside antibiotics.In this study,hydroxyl-Fe pillared montmorillonites and hydroxyl-Fe/Al pillared montmorillonites were prepared by the raw material,montmorillonite K10 with hydroxyl-Fe and hydroxyl-Al pillaring reagent.X-ray diffraction(XRD),Fourier Transform infrared spectroscopy(FT-IR),Thermogravimetric Analysis(TG-DSC),X-ray photoelectron spectroscopy(XPS),scanning electron microscope(SEM)and so on were used to characterize the K10 and pillared montmorillonite.The adsorption properties and adsorption mechanism were discussed at the same time.The results of the modified conditions influencing the montmorillonite structure showed that:with the increasement of the molar ratio,d(001)of two kinds of pillared montmorillonites were increased,The interlayer domain was amplified and the metal pillar reagent had evolved and rearranged because of hydrolysis products of Fe and Al in different stages and Keggin structure.And d(001)of Fe/Al pillared montmorillonites were generally higher than that of Fe pillared montmorillonites.The contents of Fe and Al increased,the binding energy of had changed.the thermal stability enhanced,etc..Under the same conditions(pH = 6.5),the optimum molar ratio of Fe pillared montmorillonites was 1.5 and the hydroxyl-Fe/Al pillared montmorillonites optimum molar ratio was 0.1,which were much higher than unmodified montmorillonite K10.The maximum adsorption amount(Fe/Al 0.1-mont)was greater than the sum of OH/Al-mont and 1.50H/Fe-mont,and the adsorption efficiency of 1+1>2 was achieved.According to Langmuir model,the Fe/Al 0.1-mont maximum adsorption amount would be 120 mg/g.The law that K10 and pillared montmorillonites influenced by pH was similar,the optimum pH was 9,pH?9,with the increasement of pH,adsorption amount gradually increased;pH>9,adsorption amount decreased.On the one hand,it owed to the electrostatic interaction of montmorillonite and gentamicin cations(Gen+);On the other hand,it was related to the electrochemical state of gentamicin in different pH conditions.Mechanism research showed that the adsorption included gentamicin adsorbed by ion exchange into the mineral layer,and the chemical adsorption on the surface:In addition,The mechanism of two types of pillared montmorillonites adsorbing gentamicin would be slightly different.Fe pillared montmorillonite was easily blocked up,interlayer structure collapsed during the adsorption,Oxygen made the greatest contribution to the adsorption of surface negative charge mobile;but in hydroxyl-Fe/Al pillared montmorillonites,iron had made the greatest-contribution,and uniform pore size and the stability of interlayer structure could be still remained after adsorption. |
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