Fabrication of polyamide nanofiltration membrane with tannic acid/poly(sodium 4-styrenesulfonate) network-like interlayer for enhanced desalination performance.

The traditional polyamide composite nanofiltration membranes have high selectivity and low water permeance, so it is necessary to find strategies to raise the permeance. Herein, a novel polyamide nanofiltration membranes with high permeance were fabricated by coating a loose hydrophilic network-like interlayer, where tannic acid (TA) with pentapophenol arm structure binds to poly(4-styrenesulfonate) (PSS) polymer through hydrogen and ionic interactions. The effects of the network-like TA/PSS interlayer on surface morphology, surface hydrophobicity, and the interfacial polymerization mechanism were investigated. The outcomes demonstrated that the TA/PSS interlayer can offer a favorable environment for interfacial polymerization, enhance the hydrophilicity of the substrate membrane, and delay the release of piperazine (PIP). The optimized TFC-2 presents pure water flux of 22.7 ± 2.8 L m-2 h-1 bar-1, Na2SO4 rejection of 97.1 ± 0.5 %, and PA layer thickness of about 38.9 ± 2.5 nm. This provides new strategies for seeking to prepare simple interlayers to obtain high-performance nanofiltration membranes.

Preparation of an intelligent film based on chitosan/oxidized chitin nanocrystals incorporating black rice bran anthocyanins for seafood spoilage monitoring.

A novel intelligent film was developed by immobilizing 1%, 3% and 5% black rice bran anthocyanins (BACNs) into oxidized-chitin nanocrystals (O-ChNCs)/ chitosan (CS) matrix. The ultraviolet-visible spectrum of BACNs solutions showed color variations from red to greyish green in a range of pH 2.0-12.0. Fourier transform infrared spectrum and atomic force microscope of the films showed that O-ChNC and BACNs were well dispersed into the CS matrix. Although the incorporation of BACNs decreased the mechanical and barrier properties of the CS/O-ChNCs/BACNs (COB) films, it endowed the COB films with excellent UV-barrier, antioxidant and pH sensitivity character. The results of the application trial showed that the COB films containing 3% of BACNs (COB-3) were able to monitor the spoiling of fish and shrimp by visible color changes. Therefore, the developed COB-3 films could be used as an intelligent food packaging for monitoring animal-based protein food spoilage.