LiCl·2Al(OH)3·nH2O/PVDF杂化膜的制备及提锂性能

Preparation of hybrid LiCl·2Al(OH)3·nH2O/PVDF membrane and its lithium uptaking

以氯化锂、氯化铝为原料,采用"一步法"制备LiCl·2Al(OH)3·nH2O型铝基锂吸附剂.将LiCl·2Al(OH)3·nH2O与聚偏氟乙烯(PVDF)混合,采用相转化法成功制备了具有锂吸附性能的杂化膜.探究了吸附剂负载量、膜厚对杂化膜特性以及吸附性能的影响,并探究了杂化膜的循环使用性能.实验结果表明,当LiCl·2Al(OH)3·nH2O质量分数为12%时,膜孔中出现团聚现象,同时吸附剂的增多提升了杂化膜的亲水性,水通过膜的阻力增大,使杂化膜通量降低;当杂化膜组成为质量分数16%PVDF-10%LiCl·2Al(OH)3·nH2O时,杂化膜在动态循环吸附2 h后,吸附容量达280 mg/m2,基本达到饱和,当脱附时长为120 min时,脱附量基本达到平衡;同时,增加刮膜厚度有利于提高铝基锂吸附剂杂化膜吸附/脱附容量;铝基锂吸附剂杂化膜10次连续吸附解吸后,其吸附容量仍能保持第一次的85.3%,说明制备的杂化膜具有一定的循环耐用性.

Aluminum-based lithium adsorbent[LiCl·2 Al(OH)3·nH2O]was synthesized with LiCl andAlCl3 by one-step method.The hybrid membrane with lithium adsorption property was successfully prepared by the phase conversion method of LiCl·2 Al(OH)3·nH2O and PVDF.The effects of the loading amount of the adsorbent and membrane thickness on the characteristics and the adsorption performance of the hybrid membrane were investigated.The results show that when the content of LiCl·2 Al(OH)3·nH2O is 12%,there is agglomeration in the membrane pore structure,and the increase of adsorbents improves the hydrophilicity of hybrid membrane,strengthens the resistance of water membrane,and reduces the flux of hybrid membrane;when the composition of hybrid membrane is 16%PVDF-10%LiCl·2 Al(OH)3·nH2O,the adsorption capacity(280 mg/m2)of hybrid membrane basically reaches saturation after dynamic cycle adsorption for 2 h,and the desorption capacity is basically reached equilibrium when the desorption time is 120 min;increasing the thickness of the scraped membrane is conducive to improving the adsorption/desorption capacity;after 10 consecutive adsorption/desorption,the adsorption capacity of the hybrid membrane can still maintain 85.3%of the original one,indicating that the membrane has certain cycle durability.