硝酸锂改性钛系离子筛的制备及其吸附性能

Preparation and adsorption performance of titanium based lithium ion sieve improved by LiNO3

钛系锂离子筛具有较高的锂吸附容量和稳定性,对其制备工艺及性能进行改进研究具有重要意义。使用硝酸锂和碳酸锂混合物作为锂源,与二氧化钛在500℃下进行固相反应,生成层状钛酸锂;使用0.2 mol·L^-1盐酸对其酸洗24 h,得到了锂离子筛吸附剂;采用X射线衍射、扫描电镜、粒度分析、N2吸附-脱附方法等,对其性能进行了表征;通过锂离子的吸附实验,确定了吸附和再生性能;探究了该新型吸附剂的锂离子吸附机理。结果表明:吸附过程是单分子层化学吸附;经过改性,离子筛颗粒更加细小,孔体积和比表面积更大,结构完整;在70 mg·L^-1的Li^+溶液中,吸附量为25.01 mg·g^-1,准二级吸附速率常数为0.2762 g·(mg·h)^-1,吸附速率较之未改性提高了54.56%;该离子筛对浓度为11.6 mg·L^-1的Li^+溶液,其锂去除率可以达到99.77%。

Titanium based lithium ion sieves have excellent lithium adsorption capacity and stability,and the improvement studies on its preparation and character are of great importance.A mixture of LiNO3 and Li2CO3 was used as the lithium source to synthesize laminar Li2TiO3 through the solid state reaction at 500℃,and lithium ion sieves were prepared after being put it in 0.2 mol·L^-1 hydrochloric acid pickling solution for 24 h.Physicochemical properties of the ion sieves were characterized by X-ray diffraction(XRD),scanning electronmicroscopy(SEM),particle size distribution analysis and nitrogen adsorption-desorption measurements.Adsorption,regeneration properties of the ion sieves and adsorption mechanism were investigated.It is revealed that adsorption process conforms to the monomolecular and chemical adsorption.Furthermore,micro-scale particles with higher pore volume and higher specific area were obtained after modification.Adsorption capacity and pseudo-second-order kinetic constant of 25.01 mg·g^-1 and 0.2762 g·(mg·h)^-1,respectively,were obtained by pouring the lithium ion sieves in the solution of 70 mg·L^-1 for 24 h.Hence,the increase in adsorption rate of 54.56%was observed.The removal rate of Li^+(99.77%)can be reached using this ion sieves in the solution of concentration of 11.6 mg·L^-1.