The Adsorption Of Rare Earth Ions On The Surface Of Kaolin And The Effect Of Organic Acid On It:A DFT Study

Ion-adsorbed rare earth minerals are a kind of rare earth elements adsorbed in ionic state on the surface of clay minerals such as kaolin and have high medium and heavy rare earth content.They are important supporting resources for the development of high and new technology and have important strategic significance.In this study,CASTEP module of Materials Studio software is used for quantum chemical calculation to conduct DFT research on the adsorption process of rare earth ions on kaolin surface and the desorption process of rare earth ions strengthened by organic acids on kaolin surface.The main conclusions are as follows:The electron properties of kaolin cell and(001)and(00-1)surface were analyzed,and the band gap of kaolin was 5.096 eV.The band gap width was relatively large.The charge of different parts of kaolin cell structure was different.The atomic displacement of kaolin(001)surface is more obvious than that of(00-1)surface,and the activity of Kaolin surface O atom is greater than that of(00-1)surface O atom of the flat hydroxyl group than that of(001)surface O atom of the upright and inclined hydroxyl group.The geometric center of The O atom on the surface of kaolin(00-1)is the active site,and the O atom of the flat hydroxyl group on the surface of Kaolin(001)is the active site.The surface adsorption models of rare earth ions in kaolin(001)and(00-1)under ideal conditions were analyzed.The distance from the rare earth ions to the kaolin surface is reduced compared to the initial position.The order of adsorption energy is Eu less than Lu less than Y less than La less than H2 O.The order of absolute value of total distribution on(00-1)surface of kaolin is: La less than Eu less than Y less than Lu;on(001)surface of Kaolin,the order of absolute value of total distribution on rare earth is: La less than Eu less than Y less than Lu;the bond distribution between medium and heavy rare earth and O on kaolin surface is greater.The overlapping area of state density La was less than Y,less than Eu and less than Lu;pd hybridization occurred between La,Y and Kaolin surface O;SP hybridization occurred between Eu and Kaolin surface O;SPF hybridization occurred between Lu and Kaolin surface O.The effects of acetic acid,oxalate and lactic acid on the adsorption of Y,La,Eu and Lu rare earth ions on kaolin(001)and(00-1)were studied.Different rare earth ions are affected by organic acids on different surfaces to different degrees.The binding energy of medium and heavy rare earth ions with organic acids is always greater than that of light rare earth ions,regardless of the surface.In kaolin(001)surface,strengthen the result of leaching of acetic acid root and root approximate oxalate,lactic acid root,and greater than on the surface of kaolin(00-1),strengthen the effect of leaching root acetate and lactate spikes approximation,and greater than oxalic acid root,comprehensive,on the surface of the two improved leaching effect: acetic acid root greater than the lactic acid greater than the root oxalate.