Abstract:

Polyvinylidene fluoride(PVDF)/graphene oxide(GO) nanocomposite membranes, which were made of PVDF naocomposites with different content of super hydrophilic graphene oxide(GO) nanosheets, were assessed for long term application in a membrane bioreactor(MBR) system.Critical flux, MBR performance, membrane resistance, and anti-fouling properties were intensively studied.Surface hydrophilicity of PVDF/GO membranes was improved with presence of surficial oxygen-containing groups up to 29.33%(GO=3%).PVDF/GO membranes showed similar anti-fouling to PVDF control membrane, however, PVDF/GO(GO=3%) membrane required only one cleaning with cleaning cycle 4 times longer than PVDF control.PVDF/GO membrane had lower membrane resistance than PVDF control and significant reduction in irreversible fouling resistance.As an example, PVDF/GO(GO=3%) membrane had about 9% of irreversible fouling resistance of PVDF control.Antifouling improvement of PVDF/GO membrane was further shown by EPS study that much lower EPS intensities were observed with a reduction of 59.98%(GO=1%) and 69.57%(GO=3%) in comparison to PVDF control.Scanning electron microscopy(SEM) and confocal laser scanning microscope(CLSM) results showed that cake layer on nanocomposite membrane became looser and thinner with the increase of GO content.Part of PVDF/GO(GO=3%) membrane surface was exposed, resulting in high stable permeability over a long period of time.

Key words: membrane, environment, nanomaterials, graphene oxide, hydrophilic modification, fouling

摘要：

利用强亲水性氧化石墨烯（GO）作为添加剂，自制了PVDF/GO复合微滤膜，并将其应用于MBR系统中，进行长期应用研究。研究发现，共混膜的表面性质得到改善，其表面含氧基团达到29.33%（GO=3%）；共混膜与PVDF膜对污染物的去除效果相近，但共混膜（GO=3%）仅进行了一次清洗，清洗周期是PVDF的4倍；PVDF/GO共混膜的膜阻力要低于PVDF膜，并且共混膜的不可逆污染阻力显著下降，其数值仅仅是PVDF膜的9.0%（GO=3%）；EPS分析发现，共混膜表面的EPS浓度明显减少，其降幅分别达到59.98%（GO=1%）和69.57%（GO=3%），抗污染性能显著提高；通过SEM与CLSM分析发现，随着氧化石墨烯加入量的提高，共混膜表面形成了滤饼层变得疏松，厚度也变薄，甚至露出了部分膜表面（GO=3%），保证了共混膜稳定的渗透率。

关键词: 膜, 环境, 纳米材料, 氧化石墨烯, 亲水改性, 膜污染