Polyelectrolyte aerogels with regeneration capacity for efficient removal of particulate matters

Preparation of silane-free porous structure hyperelastic phosphorylated chitosan sponge reinforced with bamboo activated carbon and its efficient PM2.5 removal

Chitosan (CS) based sponge shows important potential applications in adsorption, filtration, sensing, etc., which often requires good deformation-recovery ability that is usually achieved under the help of silane elastomers. Herein, a simple but innovative strategy was proposed that only bamboo activated carbon (BAC) was employed as the reinforcer to construct highly elastic phosphorylated chitosan (P-CS) sponge with through-hole structure like layer-support by freeze drying. In the system, the through-hole structure like layer-support was formed by directional freezing, where BAC as the "support" was fixed onto the P-CS "layer". When the through h-hole structure like layer-support is squeezed, the "support" could limit the bending of the "layer" and protect it to some extent. Therefore, the resulting P-CS/BAC composite sponge displays excellent elastic properties. Based on the through-hole structure, the P-CS/BAC composite sponge is well suited for PM2.5 filtration, achieving a filtration efficiency of 99.61 % and a low pressure drop of only 60 Pa. Besides, it has excellent flame retardance (LOI of 50.4 %) due to the synergistic effect of N and P of P-CS. The system could achieve highly elastic without any silane, meanwhile, its simple preparation and excellent performance endow it a great development prospect in air purification.

Self-supporting noncovalent Choline Alginate/Tannic acid/Ag antibacterial films for strawberry preservation

Packaging materials with peculiar antibacterial properties can shield off and inhibit microorganism proliferation, thus achieving packaging goals such as fresh-keeping, good hygiene, and biosafety. Especially, antibacterial films made of biocompatible substances have received wide attentions, which could effectively extend the shelf life, enhance food security, and guarantee economic benefits. Herein, a self-supporting hybrid antibacterial film was prepared based on non-covalently linked choline hydroxide (ChOH) and alginic acid (HAlg). Then tannic acid (TA) and silver ions were added to improve the mechanical and antimicrobial properties of this hybrid film. The rich hydroxyl groups from TA not only form multiple hydrogen bonds with ChAlg, but can also in situ reduce silver ions to silver nanoparticles, which were confirmed with various characterizations. In addition, the quantitative antibacterial test proved that the antibacterial rate was significantly improved after adding silver ions, reaching >60 %. In an actual storage test, we found that choline cation (Ch+) captured in antibacterial film by electrostatic interaction could achieve sustained release, i.e. sustainable bacteriostasis, and keep strawberries fresh for 48 h at room temperature. This work offers a new strategy for preparing antibacterial films via non-covalent weak interactions, explored an alternative antibacterial film for food packaging applications.

Nanostructured Bioaerogels as a Potential Solution for Particulate Matter Pollution

Particulate matter (PM) pollution is a significant environmental and public health issue globally. Exposure to high levels of PM, especially fine particles, can have severe health consequences. These particles can come from a variety of sources, including natural events like dust storms and wildfires, as well as human activities such as industrial processes and transportation. Although an extensive development in air filtration techniques has been made in the past few years, fine particulate matter still poses a serios and dangerous threat to human health and to our environment. Conventional air filters are fabricated from non-biodegradable and non-ecofriendly materials which can cause further environmental pollution as a result of their excessive use. Nanostructured biopolymer aerogels have shown great promise in the field of particulate matter removal. Their unique properties, renewable nature, and potential for customization make them attractive materials for air pollution control. In the present review, we discuss the meaning, properties, and advantages of nanostructured aerogels and their potential in particulate matter removal. Particulate matter pollution, types and sources of particulate matter, health effect, environmental effect, and the challenges facing scientists in particulate matter removal are also discussed in the present review. Finally, we present the most recent advances in using nanostructured bioaerogels in the removal of different types of particulate matter and discuss the challenges that we face in these applications.