Self-cleaning, superhydrophobic, and antibacterial cotton fabrics with chitosan-based composite coatings

The development of cotton fabrics with special properties such as superhydrophobicity, self-cleaning, oil/water separation, anti-bacterial activity and blood repellency without compromising its intrinsic properties such as flexibility, breathability, comfort, and biodegradability is quite challenging task. In this study, a simple and environmentally friendly approach was used to fabricate superhydrophobic cotton fabric by introducing chitosan-based composite coatings over cotton fabric. The surface properties of the cotton samples were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy. The prepared cotton fabrics showed excellent superhydrophobicity with a water contact angle of 154.4° and also possess excellent antibacterial activity against Gram positive and negative bacteria with inhibition zone of 16 mm and 22 mm in disk diffusion method and shake flask method results revealed that the chitosan-PAni-ZnO-STA coated cotton effectively inhibits the bacterial growth. Furthermore, the self-cleaning, blood repellency and oil-water separation performance of cotton fabric were also performed to examine the feasibility of as-modified cotton in both environmental and clinical applications.

Cation Exchange Membranes and Process Optimizations in Electrodialysis for Selective Metal Separation: A Review

The selective separation of metal species from various sources is highly desirable in applications such as hydrometallurgy, water treatment, and energy production but also challenging. Monovalent cation exchange membranes (CEMs) show a great potential to selectively separate one metal ion over others of the same or different valences from various effluents in electrodialysis. Selectivity among metal cations is influenced by both the inherent properties of membranes and the design and operating conditions of the electrodialysis process. The research progress and recent advances in membrane development and the implication of the electrodialysis systems on counter-ion selectivity are extensively reviewed in this work, focusing on both structure-property relationships of CEM materials and influences of process conditions and mass transport characteristics of target ions. Key membrane properties, such as charge density, water uptake, and polymer morphology, and strategies for enhancing ion selectivity are discussed. The implications of the boundary layer at the membrane surface are elucidated, where differences in the mass transport of ions at interfaces can be exploited to manipulate the transport ratio of competing counter-ions. Based on the progress, possible future R&D directions are also proposed.

Hybrid composite membranes of chitosan/sulfonated polyaniline/silica as polymer electrolyte membrane for fuel cells

A series of novel ionic cross-linked chitosan (CS) based hybrid nanocomposites were prepared by using polyaniline/nano silica (PAni/SiO₂) as inorganic filler and sulfuric acid as an ionic cross-linking agent. The CS-PAni/SiO₂ nanocomposites show enhanced mechanical properties and improved oxidative stabilities. These nanocomposites can be effectively used as environmental friendly proton exchange membranes. Incorporation of PAni/SiO₂ into CS matrix enhances water uptake and facilitates the phase separation which enables the formation of hydrophilic domains and improves the proton transport. Moreover, the doped polyaniline also provides some additional pathways for proton conduction. The membrane containing 3wt% loading of PAni/SiO₂ in chitosan (CS-PAni/SiO₂-3) exhibits high proton conductivity at 80°C (8.39×10^-3Scm^-1) in fully hydrated state due to its excellent water retention properties. Moreover, methanol permeability of the ionic cross-linked CS-PAni/SiO₂ nanocomposite membranes significantly reduces with the addition of PAni/SiO₂ nano particles. The CS-PAni/SiO₂-3 composite membrane displays the best overall performance as a polymer electrolyte membrane.

Structural and electrochemical studies of heterogeneous ion exchange membranes based on polyaniline-coated cation exchange resin particles

Polyaniline was deposited on polystyrene sulfonated divinyl benzene resin by varying polymerization time to fabricate heterogeneous PVC matrix membranes.