介孔石墨相氮化碳载银聚醚砜膜制备及性能研究

膜污染一直是膜分离应用中的主要问题。将不同量的介孔石墨相氮化碳载银(m-g-C₃N₄/Ag)以共混法引入铸膜液中, 通过相转化法制备聚醚砜(PES)纳米复合膜, 系统研究了m-g-C₃N₄/Ag的添加对纳米复合膜形貌、过滤、抗菌、光催化和抗污染性能的影响。结果表明, m-g-C₃N₄/Ag的添加可以改善纳米复合膜的断面结构及表面亲水性。与纯PES膜相比, 纳米复合膜纯水通量随着掺杂量的增加显著提高, 各个样品对蛋白质的截留率均在90%以上, 表明m-g-C₃N₄/Ag的添加在不影响截留性能的前提下, 可以显著提高纳米复合膜的过滤性能。纳米复合膜的抗菌性能随着m-g-C₃N₄/Ag含量的增加而提高, 其中对铜绿假单胞菌的抗菌效果明显高于大肠杆菌。纯PES膜在光照下几乎不发生光降解。相比之下, 所有添加m-g-C₃N₄/Ag的纳米复合膜在可见光照射下均呈现良好的光催化性能, 且光催化活性随着m-g-C₃N₄/Ag的增加而逐渐增强。其中m-g-C₃N₄/Ag添加量最高的纳米复合膜显示出最明显的光催化作用, 在120 min内甲基橙的脱色率可达63%。通过四步过滤实验对所有膜的综合抗污染性能进行表征, 可知所有纳米复合膜通量恢复率均显著高于纯PES膜。水洗和可见光照射后所有膜的膜通量恢复率皆进一步提高。综上所述, 添加m-g-C₃N₄/Ag可以显著提高聚醚砜膜的抗菌性、可见光下光催化降解染料性能, 进而改善其综合抗污染性能。

Preparation and Property of Polyethersulfone Ultrafiltration Membranes with Mesoporous-graphitic-C3N4/Ag

Membrane fouling is still the major problem for the application of membrane separation. In this study, different amounts of silver doped mesoporous graphitic carbon nitride (m-g-C₃N₄/Ag) were introduced into casting solution by blending. The polyethersulfone (PES) nanocomposite membrane was prepared via the phase-inversion method. The impacts of m-g-C₃N₄/Ag addition on the morphology, filtration, antibacterial, photocatalytic, and antifouling properties of nanocomposite membrane were systematically studied. The results showed that the addition of m-g-C₃N₄/Ag can improve the cross-section structure of the nanocomposite membrane as well as its surface hydrophilicity. Compared with pure PES membrane, the pure water flux of the modified nanocomposite membrane increased significantly with the increase of doping amount. The protein rejection rates of all samples were over 90%, indicating that the addition of m-g-C₃N₄/Ag can significantly improve the filtration performance of the nanocomposite membrane without sacrificing the rejection performance. The anti-bacterial activity of the nanocomposite membranes was improved with the increase of m-g-C₃N₄/Ag content in which the anti-bacterial activity to P. aeruginosa was much more significant than that to E. coli. The pure PES membrane almost had not photodegradation under light irradiation. By contrast, all nanocomposite membranes exhibited good photocatalytic properties under visible light irradiation, and the photocatalytic activity improved with increase of m-g-C₃N₄/Ag. The nanocomposite membrane in which the m-g-C₃N₄/Ag content was the highest that showed the optimal photocatalysis, and the decolorization rate of methyl orange reached 63% in 120 min. The comprehensive antifouling performances of all membranes were characterized by four-step filtration experiments. It can be seen that the flux recovery ratio (FRR) of all nanocomposite membranes is much higher than that of PES membrane. The FRR of all membranes was further increased after washing with water and irradiating with visible light. In summary, the addition of m-g-C₃N₄/Ag can endow the PES membrane with the antibacterial and the photocatalytic properties under visible light irradiation, thereby improving its comprehensive antifouling performance.