Confinement effect of network-structured carbon dots/cellulose nanofiber/magnesium hydroxide for enhanced heavy metal ions capture and immobilization.

To solve pollution problem of heavy metal ions (HMIs) and recover them for sustainable development, a high-efficient-sewage treatment agent, carbon dots/cellulose nanofiber/Mg(OH)2 (CCMg), has been fabricated via a simple hydrothermal method. A variety of characterizations show that cellulose nanofiber (CNF) formed a layered-net structure. Hexagonal Mg(OH)2 flakes of about 100 nm has been attached on CNF. Carbon dots (CDs) around 10-20 nm in size were produced from CNF and distributed along CNF. The extraordinary structural feature endows CCMg with high removal performance towards HMIs. The up-taken capacities reach 992.8 and 667.3 mg g-1 for Cd2+ and Cu2+, respectively. The composite bears excellent durability in treating wastewater. Notably, the qualification of the drinking water can be satisfied while applying CCMg to handle Cu2+ wastewater. The mechanism of removal process has been proposed. Practically, Cd2+/Cu2+ ions were immobilized by CNF due to the space confinement effect. It achieves the facile separation and recovery of HMIs from the sewage, and more importantly, eliminates the risk of secondary contamination.

Van der Waals enhanced interfacial interaction in cellulose/zinc oxide nanocomposite coupled by graphitic carbon nitride.

In-depth understanding of interfacial property is the key to guiding the synthesis of biomass composites with desired performance. However, the exploration is of great challenge due to limitations of experimental techniques in locating hydrogen, requiring large/good crystals and detecting a weak interaction like van der Waals (vdW). Herein, we experimentally and computationally investigated the composite cellulose/zinc oxide/g-C3N4. Hydrothermal synthesis afforded cellulose/ZnO, and then fabricated the ternary composite by adding g-C3N4 under ultrasonic condition. Three components are found to co-exist in the composite, and the ZnO nanoparticle is attaching to cellulose and coupling with g-C3N4. These experimental findings were corroborated by relativistic DFT calculations. The interfacial coupling is elaborated as contributions of dative bonds, hydrogen bonds and vdW interaction. The vdW is increased by a factor of 4.23 in the ZnO/g-C3N4 interface. This improves electron-hole separation and offers prospective application of the composite in photocatalysis, antibacteria and gas sensing.

Experimental and first-principle computational exploration on biomass cellulose/magnesium hydroxide composite: Local structure, interfacial interaction and antibacterial property.

The specification of the local structure and clarification of interfacial interactions of biomass composites is of tremendous significance in synthesizing novel materials and advancing their performance in various demanding applications. However, it remains challenging due to the limitations of experimental techniques, particularly for the manner that biomass composites commonly have hydrogen bonds involved in the vicinity of active sites and interfaces. Herein, the cellulose/Mg(OH)2 nanocomposite has been synthesized via a simple hydrothermal approach and examined by density functional theory (DFT) calculations. The composite exhibits a layered morphology; Mg(OH)2 flakes are around 50 nm in size and well-dispersed. They either anchor onto the cellulose surface or intercalate between layers. The specific composite structure was confirmed theoretically, in line with XRD, SEM and TEM observations. The interfacial interactions were found to be hydrogen bonding. The average adsorption energy per hydroxyl group was computed to be within -0.47 and -0.26 eV for a composite model comprising three cellulose chains and a two-layered Mg(OH)2 cluster. The combined computational/experimental results allow to postulate the antibacterial mechanism of the nanocomposite.