以TiO2和LiOH·H2O为原料,经水热反应、煅烧后得到纳米级别锂吸附剂前驱体Li2TiO3.用盐酸将Li+洗脱后得到纳米级别锂吸附剂H2TiO3.通过XRD、SEM、动力学测试等手段考察煅烧温度、煅烧时间对吸附剂的结构和洗脱吸附性能的影响,用拟一级和拟二级动力学方程对吸附过程进行拟合,并用Langmuir和Freundlich等温线方程拟合吸附平衡数据.结果表明:在773 K下煅烧2 h制备的吸附剂对锂离子吸附容量最高达到36.16 mg/g,并且具有极快的洗脱和吸附速率;洗脱5 h时,锂洗脱率为98.8%,吸附速率常数达到0.0339 g/(mg·h);吸附动力学符合拟二级动力学方程,吸附平衡数据符合Freundlich方程,锂离子对镁离子的分离因子达到154.17.
Nano scale H2TiO3 adsorbent was obtained by acid-modifying adsorbent precursor Li2TiO3, which was synthesized by calcining products of hydrothermal reaction between TiO2 and LiOH·H2O. The effects of calcination time and calcination temperature on structure and ion-exchange properties were investigated via XRD, SEM and kinetic experiment. The pseudo- first and second order rate equations were used to investigate the adsorption process, and the Langmuir and Freundlich adsorption isotherm equations were fitted by the equilibrium data. The results show that the verified optimal calcination temperature and time are 773 K and 2 h, respectively. For such prepared adsorbent, the maximum adsorption capacity reaches 36.16 mg/g, the adsorption kinetic constants is 0.0339 g/(mg·h) and the extraction rate of lithium is 98.8% after 5 h. Moreover, the adsorption process obeys a pseudo-second order equation, and the equilibrium data fits well to the Freundlich model. The separation coefficient of Li+ to Mg2+ reaches 154.17.
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