Functionalizing a Polyelectrolyte Complex with Chitosan Derivatives to Tailor Membrane Surface Properties

Self-Assembled CMC/UiO-66-NH2 Membrane with Anti-Crude Oil Adhesion Property for Highly Efficient Oil-Water Separation

Developing the high-anti-fouling membrane has kept continuous attention in oil/water emulsion treatment. However, the majority of works on anti-fouling membranes mainly focused on low-viscosity oils, which greatly limited the development and application of a membrane to face the real crude oil wastewater. Inspired by the hydrophilicity of sodium carboxymethyl cellulose (CMC) and zirconium base metal-organic frame (Zr-MOF), an anti-oil-fouling CMC/UiO-66-NH₂ composite membrane was constructed by a self-assembly method. Profiting from the hydrophilicity and micro-nanostructure of the CMC/UiO-66-NH₂ layer, the obtained CMC/UiO-66-NH₂ membranes displayed underwater superoleophobicity and desired oil resistance. It could display the effective separation capability with 1282 ± 62 to 6160 ± 81 L/(m²·h·bar) and above 99.08% toward the different light oil emulsions. More importantly, the CMC/UiO-66-NH₂ membrane displayed ultralow crude oil adhesion behaviors toward the crude oil emulsions, which could achieve a considerably high flux (746 ± 60 to 5224 ± 87 L/(m²·h·bar)). Furthermore, electrostatic interaction and physical enwinding-wrapping between CMC and UiO-66-NH₂ also endowed the composite membranes with outstanding stability. After immersing the as-prepared membranes into the harsh environments for 24 h, the membranes still maintained high underwater-oil contact angles (UWOCA > 155°) and separation ability (oil rejection was above 99.0%). Therefore, CMC/UiO-66-NH₂ composite membranes could demonstrate promising prospects in real oily emulsion treatment.

The key to maximizing the benefits of antimicrobial and self-cleaning coatings is to fully determine their risks

Antimicrobial and self-cleaning nanomaterial coatings have attracted significant research attention in recent years due to the growing global threat of infectious diseases, the emergence of new diseases such as COVID-19, and increases in healthcare-associated infections. Although there are many reportedly successful coating technologies, the evaluation of antimicrobial performance is primarily conducted under simple laboratory conditions without adequate testing under real environmental conditions that reflect practical use and more importantly, reveal unintended outcomes. Furthermore, there is no standardized evaluation methodology to assess the long-term stability or the consequences associated with coating deterioration, such as the ecological impacts of nanomaterials or the proliferation of antibiotic-resistant bacteria/genes. In this review, we propose a precautionary framework that integrates a rigorous assessment of potential risks and limitations of nanomaterial coatings for antimicrobial applications as intrinsic to a comprehensive evaluation of their benefits. In addition, we summarize some emerging coating technologies as promising strategies to minimize unintended risks and enhance performance.