Preparation And Property Of A New Type Lithium Ion Sieve

Lithium and its compounds are widely used,mainly applied to traditional glass,ceramics,new type high-energy batteries,medical,aerospace technology,functional materials and nuclear fusion power,etc.Lithium resources in China,mainly exists in liquid solution,such as lithium resources in the salt lakes account for about 80%of the total,which are mainly distributed in the qinghai-tibet plateau.Therefore,the lithium extracted from liquid lithium resources is given more and more concern and attention by scholars both at home and abroad.Currently,most studied in the ion sieve are mainly including lithium manganese lithium ion sieve and titanium lithium lithium ion sieve from salt lake brine,however there is some serious problem with these,such as manganese/titanium dissolving loss,which isn’t conducive to industrial application.Thus,solving the dissolving loss is the most important issue currently facing.In this experiment,we will introduce the niobium in the study of lithium ionic sieve to prepare lithium ionic sieve adsorbents which are low loss rate and high adsorption.A new type of lithium ion-sieve HNbO₃,which has ultra-low loss rate,was prepared through eluting LiNbO₃ with nitric acid,using Li₂CO₃ and Nb₂O₅ as raw materials by a solid state reaction.Characterize its physical properties by X-ray diffraction technique（XRD）and scanning electron microscope（SEM）,discuss the adsorption charateristic of ionic sieve,and analyze the influence of the elution time on lithium elution rate and niobium dissolving rate.The results show that the mole ratio of lithium niobate and calcination temperature both have an impact on the crystal structure of lithium niobate compounds LiNbO₃ and saturated adsorption amount of the corresponding lithium ionic sieve.The saturated adsorption capacity of Ionic sieve samples showed a trend of increaseing before falling with lithium niobate molar ratio increasing,which is identical to the calcination temperature.And lithium niobate molar ratio is 1,and calcination temperature is 723 ℃.Washing LiNbO₃ with 75 mL 8 mol/L HNO₃ for 6 d,it was found that lithium elution rate was 83%,and the soluble loss rate of niobium was negligible,which solved the problem of itself ion loss.The saturated adsorption capacity is about 16 mg/g in a mixed simulation mixture containing Li+.The adsorption process fitted pseudo-second-order kinetic equation and the Langmuir isotherm equation,which suggest the adsorption process belongs to monolayer adsorption and mainly chemical adsorption.In addition,precursor LiNb_1-xM_xO₃（M = Mn,Ti;0≤ x ≤1.0）was prepared by doping two metal elements such as Mn,Ti based on LiNbO₃,and its corresponding ionic sieve could be prepared after nitric acid eluting.The effect of doping with a small amount of Mn,Ti metal elements in the crystal structure of complex oxide ionic sieve isn’t obvious,and the difference of the XRD pattern is also not quite clear.With the increase of doping amount in the precursor,lithium elution rate increases,and the soluble loss rate of Nb iremains relatively stable,keeping at 0,and Ti soluble loss rate decreases after the first rising trend.Meanwhile,the saturated adsorption capacity（Q）of ionic sieve（H-X）were gradually increased.