纳米H_(2)TiO_(3)锂离子筛的制备及吸附性能研究

Preparation and adsorption performances of nano-H_(2)TiO_(3) lithium-ion sieve

以TiO_(2)和LiOH·H_(2)O为原料,Zr(NO_(3))_(4)·5H_(2)O为掺杂剂,采用高温固相和离子交换法制备了纳米H_(2)TiO_(3)锂离子筛。采用X射线衍射(XRD)、扫描电子显微镜(SEM)、N 2吸附脱附技术等手段对H_(2)TiO_(3)锂离子筛的晶型、形貌和孔结构进行了表征,并以H_(2)TiO_(3)为锂离子吸附剂,LiCl溶液为模拟卤水,研究了pH值、时间和温度对Li^(+)的吸附性能。结果表明,Zr^(4+)掺杂未引起Li 2TiO_(3)晶型变化,且掺杂后Zr-H_(2)TiO_(3)的BET比表面积(18.16 m^(2)/g)和孔体积(0.0712 cm^(3)/g)均有所增大。溶液pH值增大有利于Li^(+)吸附,当pH=12.15时Zr-H_(2)TiO_(3)的Li^(+)吸附容量为21.66 mg/g,高于H_(2)TiO_(3)的吸附容量(18.79 mg/g)。H_(2)TiO_(3)和Zr-H_(2)TiO_(3)吸附Li^(+)行为符合准二级动力学模型,以化学吸附为主,吸附反应的ΔH为正,表明吸附过程为吸热反应。

Zr^(4+)-Doped titanium lithium ion sieve was prepared by high temperature solid phase and ion exchange methods by using TiO_(2) and LiOH·H_(2)O as raw materials,and Zr(NO_(3))_(4)·5H_(2)O as doping modifier.X-ray diffraction(XRD),scanning electron microscopy(SEM),and N_(2) adsorption/desorption technologies were employed to characterize the crystalline,morphology and pore structure of the nano-H_(2)TiO_(3) lithium ion sieve.Taking H_(2)TiO_(3) as adsorbent and LiCl solution as simulated brine,the adsorption performances of pH value,reaction time and temperature for Li^(+) were studied.The results showed that Zr^(4+) doping did not cause the crystal type change of Li 2TiO_(3).The BET surface area(18.16 m^(2)/g)and pore volume(0.0712 cm^(3)/g)of H_(2)TiO_(3)increased after Zr^(4+) doping.The adsorption results showed that the increase of pH value was conducive to Li^(+) adsorption.The lithium adsorption capacity of Zr-H_(2)TiO_(3) is 21.66 mg/g when pH=12.15,which is higher than that of H_(2)TiO_(3) lithium-ion sieve(18.79 mg/g).The Li^(+) adsorption behavior of H_(2)TiO_(3)and Zr-H_(2)TiO_(3) conforms to the pseudo-second-order kinetic model,indicating that the process is chemisorption.The positiveΔH value of adsorption reaction indicated that the adsorption process was endothermic.