聚氯乙烯锂离子筛膜的制备及其在卤水中的锂吸附性能

Preparation of polyvinyl chloride lithium ion sieve membrane and its lithium adsorption properties in brine

锂离子筛的成型技术对于其在卤水中的工业化生产应用具有重要意义。以聚氯乙烯(PVC)为成膜材料,聚甲基丙烯酸甲酯(PMMA)和聚乙烯吡咯烷酮(PVP_(k30))为改性剂,制备了负载Li_(1.6)Mn_(1.6)O_(4)的PVC锂离子筛前驱体膜,研究了膜经稀盐酸抽锂后得到的PVC锂离子筛膜对锂的吸附性能及循环吸附解吸性能等,并对离子筛膜进行了吸附动力学及吸附等温模型分析。结果表明:PVC浓度为10wt%,PMMA的添加量为6wt%,PVP_(k30)的添加量为2wt%,Li_(1.6)Mn_(1.6)O_(4)含量为20wt%联用时,制得的离子筛膜吸附量为1336.30 mg/m^(2)。经0.1 mol·L^(−1)HCl溶液解吸,约2 h时解吸达到平衡,锰的溶损率为0.56%左右。在卤水中进行了10次循环吸附解吸过程,吸附量降至1294.16 mg/m^(2),吸附量仅损失了3%。在含有多种复杂离子如Na^(+)、K^(+)、Mg^(2+)和Ca^(2+)的卤水中,锂离子筛膜对Li^(+)有很高的选择性。说明该PVC锂离子筛膜结构稳定,循环利用性能优异,有利于其工业化应用。PVC锂离子筛膜的吸附过程更符合伪二级动力学方程及Langmuir吸附等温模型,说明该吸附过程的吸附类型为单分子层化学吸附。膜状的离子筛对于从盐湖卤水等液态锂资源中提取锂具有很大的开发潜力。

Lithium ion sieve formation technology for Li+recovery industrial production and application from brine is very important.Polyvinyl chloride(PVC)-Li_(1.6)Mn_(1.6)O_(4) lithium ion sieve precursor membrane was prepared by blend of Li_(1.6)Mn_(1.6)O_(4) with PVC,polymethyl methacrylate(PMMA)and polyvinylpyrrolidone(PVP_(k30)).After the precursor membrane was treated with HCl solution it can uptake lithium.A series of experiments for examining its adsorption and cyclic performance were carried out.The adsorption isotherm model and the adsorption kinetics of PVC lithium ion sieve membrane were analyzed.The results showed that the adsorption capacity of PVC lithium ion sieve membrane was 1336.30 mg/m^(2)when the concentration of PVC was 10wt%,the content of PMMA was 6wt%,the content of PVP_(k30) was 2wt%,and the amount of loading of Li_(1.6)Mn_(1.6)O_(4) was 20wt%.After treated with 0.1 mol·L^(−1)HCl for 2 h,the lithium extraction reached equilibrium and the dissolution loss rate of Mn^(2+)was about 0.56%.After 10 cycles of adsorption and desorption in brine,the Li^(+)adsorption capacity was lost only 3.0%(from 1336.30 mg/m^(2)to 1294.16 mg/m^(2)).The PVC lithium ion sieve membrane showed great selectivity for Li+in brine containing a variety of complex ions such as Na^(+),K^(+),Mg^(2+)and Ca^(2+).The PVC lithium ion sieve membrane has stable structure and excellent recycling performance,which is conducive to its industrial application.The PVC lithium ion sieve membrane accords with the pseudo second order kinetic equation and Langmuir adsorption isotherm model,indicating a monolayer chemisorption.It is potential to be used in enrichment and recovery of lithium from salt lake brine and other liquid lithium sources.