Preparation Of Magnetic Montmorillonite And Its Adsorption Properties For Tetracycline And Ciprofloxacin

Clay minerals are natural materials widely existed in nature.They can be used as adsorbent owing to their special pore structure.Due to the fact that solid-liquid is always difficult to separate after water treatment,therefore,solvothermal method is used to synthesize magnetic clay composites in one step to solve the problem.Two sorts of antibiotics,tetracycline?TC?and ciprofloxacin?CIP?,were selected as indicative pollutants.The development and application of adsorption materials were explored by studying their adsorption properties on magnetic clay materials.?1?Five kinds of clay materials?rectorite,volcanic rock,vermiculite,montmorillonite,diatomite?were selected as adsorbents to investigate their adsorption of TC and CIP in water body.The adsorbent with the best adsorption capacity was selected.Experiments have shown that montmorillonite is the adsorbent with excellent performance.?2?The magnetic montmorillonite?CoFe₂O₄/MMT?composite was prepared by one-step solvothermal method.The structure and properties of the material were characterized by FTIR,XRD,SEM,BET and VSM.The results showed that some CoFe₂O₄ particles entered the layer of montmorillonite,and some partially distributed on the surface of montmorillonite.At the same time,it also has high magnetization saturation strength and low remanence value,indicating that it has superparamagnetic properties.After the adsorption experiment,solid-liquid separation can be quickly achieved with the help of external magnetic field.?3?Using the prepared magnetic montmorillonite as adsorbent,the changes of adsorption capacity of TC and CIP under different factors,such as solution pH,adsorption time,initial concentration,temperature and ionic strength,were investigated.Adsorption kinetics,adsorption isotherms and adsorption thermodynamics simulations were carried out in this paper.The results showed that the adsorption of TC and CIP by magnetic montmorillonite was consistent with the pseudo-second-kinetic model and the Langmuir-Freundlich model;the adsorption process of TC and CIP by magnetic montmorillonite was spontaneous and the entropy increased.In addition,the adsorption process of TC was endothermic,and the adsorption process of CIP was exothermic.?4?Photocatalytic degradation experiments were carried out and it was found that magnetic montmorillonite has certain photocatalytic activity.Calcination was used to regenerate magnetic montmorillonite,and the regeneration rate can still reach up to 80%after regeneration for three times.?5?The effect of magnetic montmorillonite on the adsorption behavior of TC in soil was explored,it was found that magnetic montmorillonite would compete with soil for adsorption,and its adsorption for TC is far stronger than soil.Tetracycline would be preferentially adsorbed by magnetic montmorillonite.Therefore,the pollutants will be immobilized and stabilized avoiding further pollution.