Adsorption Ability Of Clay Minerals To Heavy Metal Ions

At present,wastewater,sewage discharged by various production enterprises and mining of large-scale deposits have caused serious heavy metal ion pollution,which poses a threat to human living environment.The special molecular structure and irregular crystal defects of clay minerals lead to their good adsorption properties for heavy metal ions and have broad application prospects.Three representative clay minerals,bentonite（mainly montmorillonite）,kaolin（mainly kaolinite）and illite,were selected as experimental materials.Through a series of static adsorption experiments,the effects of three clay minerals on Cu²⁺,Pb²⁺and Cd²⁺in simulated industrial wastewater solution were investigated in turn.The adsorption capacity of bentonite,kaolin and illite was compared by measuring the adsorption capacity of the same heavy metal ions on three clay minerals.In addition,in view of the fact that there are many different heavy metal ions in the actual industrial wastewater,this paper also studied the separation of heavy metals through experiments.The competitive adsorption characteristics of bentonite,kaolin and illite were determined,and the adsorption selectivity of Cu ²⁺,Pb ²⁺,Cd ²⁺was determined.The adsorption stability of used bentonite,kaolin and illite to heavy metal ions was studied.The results show that under the same experimental conditions,kaolin is the weakest,illite is slightly stronger,bentonite has the strongest adsorption capacity for heavy metal ions;different clay minerals also have selective adsorption for heavy metal ions;the selectivity of kaolin and illite is Pb²⁺>Cu²⁺>Cd²⁺;the selectivity of bentonite is Cu²⁺>Cd²⁺>Pb²⁺;in a certain range,increasing the use of adsorbents,increasing the pH value of the solution and the adsorption environment temperature,prolonging the adsorption process time can improve the adsorption efficiency of clay minerals to heavy metal ions in varying degrees;the adsorption of heavy metal ions on kaolin conforms to Langmuir adsorption model,illite to heavy gold The adsorption of metal ions conforms to Langmuir adsorption model,the adsorption of heavy metal ions by bentonite conforms to Freundlich adsorption model,and the adsorption of heavy metal ions by three clay minerals conforms to quasi-second-order kinetic model.