Bio & Medicine

A novel approach to effective wastewater treatment: Carbon nanotube membranes that are cross-stacked and super-aligned

Layer partition innovation has been broadly perceived as a more profitable innovation, inferable from its high treatment effectiveness, low impression, and solid emanating quality. However, membrane fouling has hampered its continued, sustainable growth. Although numerous modification strategies have been employed in recent decades to enhance antifouling performance, the resulting membranes typically have a more complex surface chemistry, making it difficult to control membrane fouling.

The extremity of particles basically decides their atomic connection. Because their electric dipole moment is close to zero, nonpolar membranes may be better at antifouling because pollutants can’t get on the membrane’s surface. However, previous studies on membrane fabrication and modification rarely took into account such a fundamental interaction mechanism.

Additionally, prior research on membrane preparation has not sufficiently addressed the issue of nonpolar materials. Despite the fact that carbon nanotubes have been progressively utilized for film creation, the possible valuable impacts of their nonpolar component have been scarcely researched. Although vertically aligned CNT membranes were developed in a few studies, their limited pore size and porosity make them unsuitable for micro- or ultrafiltration processes.

To address these boundaries, specialists from Beijing Ranger Service College and Tsinghua College arranged a nonpolar super-adjusted CNT (SACNT) film with a layer-by-layer cross-attaching system. Their research reveals that the chemistry of the SACNT membrane surface is simple and inert, potentially preventing membrane fouling caused by covalent bonding.

The nonpolar cross-stacked super-aligned carbon nanotube membrane for efficient wastewater treatment will be published online in Frontiers of Environmental Science and Engineering in 2023. In addition, the SACNT membranes achieved significantly higher selectivity when compared to commercial membranes.

In this review, the exploration group observed that the surface science of the SACNT films is basic and latent, subsequently possibly killing the covalent-holding-prompted layer fouling. Furthermore, the SACNT films showed commonplace nonpolar wetting conduct, with high contact plots for polar fluids (water: 124.9°–126.5°; formamide: 80.0°–83.9°), but nonpolar diiodomethane has low contact angles (18.8°–20.9°). Their study produced a structure that was smoother, more uniform, and had a higher permeability than commercial membranes. In municipal wastewater treatment, the SACNT membrane increased cleaning efficiency by 2.3 times and achieved 99.2% oil/water separation efficiency.

Using nonpolar carbon nanotubes as the raw material and a layer-by-layer cross-stacking technique, this study successfully proposed a novel nonpolar SACNT membrane. In addition to offering a novel solution to the issue of membrane pollution in membrane separation technology, this work also enhances the effectiveness of municipal sewage treatment and waste water recovery, both of which have numerous potential fields of application.

More information: Shuang Zhang et al, Nonpolar cross-stacked super-aligned carbon nanotube membrane for efficient wastewater treatment, Frontiers of Environmental Science & Engineering (2022). DOI: 10.1007/s11783-023-1630-3

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