Frappa Mirko, Macedonio Francesca, Gugliuzza Annarosa, Jin Wanqin, Drioli Enrico
Institute on Membrane Technology, National Research Council of Italy (CNR-ITM), via Bucci 17/C, 87036 Rende, Italy.
State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, 30 Puzhou Road (S), Nanjing 211816, China.
Membranes (Basel). 2021 Apr 21;11(5):302. doi: 10.3390/membranes11050302.
Membrane crystallization (MCr) is a promising and innovative process for the recovery of freshwater from seawater and for the production of salt crystals from the brine streams of desalination plants. In the present work, composite polymeric membranes for membrane crystallization were fabricated using graphene and bismuth telluride inks prepared according to the wet-jet milling (WJM) technology. A comparison between PVDF-based membranes containing a few layers of graphene or bismuth telluride and PVDF-pristine membranes was carried out. Among the 2D composite membranes, PVDF with bismuth telluride at higher concentration (7%) exhibited the highest flux (about 3.9 L∙mh, in MCr experiments performed with 5 M NaCl solution as feed, and at a temperature of 34 ± 0.2 °C at the feed side and 11 ± 0.2 °C at the permeate side). The confinement of graphene and bismuth telluride in PVDF membranes produced more uniform NaCl crystals with respect to the pristine PVDF membrane, especially in the case of few-layer graphene. All the membranes showed rejection equal to or higher than 99.9% (up to 99.99% in the case of the membrane with graphene). The high rejection together with the good trans-membrane flux confirmed the interesting performance of the process, without any wetting phenomena, at least during the performed crystallization tests.
膜结晶（MCr）是一种很有前景的创新工艺，可用于从海水中回收淡水以及从海水淡化厂的盐水流中生产盐晶体。在本工作中，采用根据湿喷磨（WJM）技术制备的石墨烯和碲化铋油墨制备了用于膜结晶的复合聚合物膜。对含有几层石墨烯或碲化铋的聚偏氟乙烯（PVDF）基膜与纯PVDF膜进行了比较。在二维复合膜中，碲化铋浓度较高（7%）的PVDF膜表现出最高通量（在以5 M NaCl溶液为进料、进料侧温度为34±0.2°C、渗透侧温度为11±0.2°C进行的MCr实验中，通量约为3.9 L∙mh）。与纯PVDF膜相比, PVDF膜中石墨烯和碲化铋的限制作用产生了更均匀的NaCl晶体，特别是在少层石墨烯的情况下。所有膜的截留率均等于或高于99.9%（含石墨烯的膜截留率高达99.99%）。高截留率和良好的跨膜通量证实了该工艺在至少所进行的结晶测试期间具有令人感兴趣的性能，且无任何润湿现象。
