硝酸锂改性钛系离子筛的制备及其吸附性能

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、N ₂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%。

Preparation and adsorption performance of titanium based lithium ion sieve improved by LiNO 3

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 LiNO ₃ and Li ₂CO ₃was used as the lithium source to synthesize laminar Li ₂TiO ₃ 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.