海胆球形锰酸锂修饰碳糊型锂离子选择电极的研究

Investigation on lithium ion-selective electrode based on sea-urchins spherical spinel LiMn2O4

建立了一种新的锂离子选择电极体系，以水热法的MnO2为原料制备海胆球形的尖晶石锰酸锂，以其为活性载体，采用压片技术制备了锰酸锂-碳糊电极（LMO-CPE），该电极对Li＋具有优良的电位响应特性。并探讨了响应机理，系统研究了电极组分配比、适用的pH值范围、检测下限、选择性系数等性能。实验结果表明：锰酸锂：乙炔黑：石蜡（质量分数比）=20∶50∶30时制备的LMO-CPE电极在1×10-5~1×10-1 mol/L范围内出现能斯特响应， pH=10时的响应性能最好，响应时间15 s以下，斜率可达到67．17 mV/dec，检测下限7．76×10-6 mol/L；采用混合溶液法测得Na＋和K＋选择性系数分别为1．02×10-3和1．97×10-3，Ca2＋、Mg2＋、Ba2＋的选择性系数在10-5数量级以下，该类电极对于其他碱金属和碱土金属离子有好的选择性。

A novel lithium ion-selective electrode constituted of a carbon paste electrode （CPE） modified with a Sea-urchins spherical spinel-type LiMn2O4 （LMO） has been investigated. The LiMn2O4 was prepared by MnO2 with Sea-urchins spherical which prepared with a common hydrothermal method. Experimental parameters, such as influence of the ratio of LiMn2O4 and paraffin oil, pH of the carrier solution and selectivity for Li＋against other alkali and alkaline-earth ions were investigated. The Li＋LMO-CPE with optimum composition exhibited a good linear response of 67.17 mV/dec in the range of 1×10-5~1×10-1 mol/L over a wide pH10 （NH3＆#183;H2O-NH4Cl buffer） and detection limit of 7.76×10-6 mol/L. Selectivity coefficients, Ki,j, have been determined for the LMO-CPE using a fixed interference methodology.Considering the interference of hydrogen ions, the K is 1.02×10-3,the K is 1.97×10-3. And the selectivity coefficients of Ca2＋、Mg2＋、Ba2＋are all less than 10-5 . Therefore, the LMO-CPE has a highly selectivity for lithium ion over alkali and alkline earth ions.