Chemistry and Chemical Engineering Research Center of Iran, Tehran, P.O. Box: 14335-186, Iran.
Chemistry and Chemical Engineering Research Center of Iran, Tehran, P.O. Box: 14335-186, Iran.
J Environ Manage. 2020 May 1;261:110189. doi: 10.1016/j.jenvman.2020.110189. Epub 2020 Mar 2.
The removal of styrene from wastewater by pervaporation was investigated by using composite PDMS membranes filled with reduced graphene oxide on PES support layers. Graphene oxide was synthesized through modified Hummers' method and then chemically reduced. The filler was characterized by TEM, SEM, XRD, and AFM. The top layers with different PDMS molecular weights were cast on the PES supports, which were prepared by phase inversion method. The characterizations of prepared membranes were investigated by SEM, AFM, contact angle measurement, TGA, and DSC. It was observed that presence of the filler in the polymeric matrix controls the swelling of the membrane and enhances its solubility parameter in favor of styrene. Moreover, it significantly improves the thermal stability of the membranes. The mechanism of separation in the process was found to be affected mainly by enhancing in the membrane's solubility rather than in its diffusivity. The pervaporative performance of prepared membranes showed their great affinity toward styrene so that the separation factor of the optimum membrane (M2/S) was increased about 250% (600.4 in comparison to 241.4 for the unfilled membrane) while its total flux was decreased from 772.5 g m.hfor the unfilled membrane to 321.9 g m.h. Increasing the molecular weight of PDMS lowered the optimal rGO content due to the complexity of the diffusion path and occupation of free volume by longer polymer chains. Accordingly, a lower total flux (124.7 g m.h for high MW compared to 718.0 g m.h for low MW) and higher separation factor (822.5 for high MW compared to 230.8 for low MW) were yielded for the same filler content (0.1 wt% rGO).
采用填充还原氧化石墨烯的聚二甲基硅氧烷（PDMS）复合膜，通过渗透汽化法从废水中去除苯乙烯。氧化石墨烯通过改良的 Hummers 法合成，然后进行化学还原。通过 TEM、SEM、XRD 和 AFM 对填充剂进行了表征。采用相转化法制备了聚醚砜（PES）支撑层，在其上浇铸了具有不同 PDMS 分子量的顶层。通过 SEM、AFM、接触角测量、TGA 和 DSC 对制备的膜进行了表征。结果表明，填充剂在聚合物基质中的存在控制着膜的溶胀，提高了其在苯乙烯中的溶解度参数。此外，它还显著提高了膜的热稳定性。分离过程中的分离机制主要受到膜的溶解度而不是扩散率的增强的影响。所制备的膜的渗透蒸发性能表明，它们对苯乙烯具有很大的亲和力，因此最佳膜（M2/S）的分离因子增加了约 250%（600.4 与未填充膜的 241.4 相比），而其总通量从未填充膜的 772.5 g·m-2·h-1降低至 321.9 g·m-2·h-1。由于扩散路径的复杂性和长聚合物链占据自由体积，PDMS 的分子量增加会降低最佳 rGO 含量。因此，对于相同的填充剂含量（0.1wt% rGO），总通量（高 MW 为 124.7 g·m-2·h-1，低 MW 为 718.0 g·m-2·h-1）较低，分离因子（高 MW 为 822.5，低 MW 为 230.8）较高。
