To explore the interactions of nanoparticles and bioresources and elucidate their effects on the morphology of the resulting composite, hierarchically structured cellulose@ZnO composites have been synthesized by an environmentally friendly hydrothermal method in one step. First, self-assembly induces the formation of hierarchical three-level structures, including cellulose/ZnO nanofibers, layers, and microfibers. Then, ZnO microparticles deposit onto the surface of the third-level cellulose/ZnO microfibers and accomplish the fabrication of a cellulose@ZnO composite, which eventually defines the hierarchical morphology of synthesized materials. The self-assembly mechanism was comprehensively examined. The electrostatic attraction between cellulose and ZnO, not hydrogen bonding, was found to be the main driving force for the formation of the first-level structure. A density functional theory study was conducted to support the self-assembly mechanism by optimizing the cellulose/ZnO structures at the molecular level, computing the corresponding thermodynamic energies and examining the spectroscopic properties. A hierarchically structured cellulose@ZnO composite is found to enhance the antibacterial activities. The diameters of the inhibition zone were found to be 48.8 and 45.5 mm against the Gram-positive bacterium Staphylococcus aureus (S. aureus) and the Gram-negative bacterium Escherichia coli (E. coli), respectively. This study is expected to improve food packaging materials while utilizing our newly synthesized cellulose@ZnO composite.

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The ZnO/Ag/cellulose composite (ZAC) with excellent photocatalytic activity of degrading benzene and phenol in VOCs has been successfully synthesized. EDS, TEM, XPS and UV-vis analyses show that the ZAC is a ternary composite. It is composed of Ag, ZnO and cellulose, where the cellulose works as the substrate to anchor the other two components. The X-ray diffraction patterns find well-crystallized ZnO nanoparticles. Multiple PL peaks in the visible region measured for ZAC, imply rich defects on ZnO. It is observed that Ag nanoparticles are mainly attached on ZnO in the composite, which would raise the separation efficiency of photogenerated electrons and holes. Photocatalytic degradation shows that ZAC is able to decompose almost 100% phenol and 19% benzene in VOCs under UV light irradiation (6 W) which is almost no harm to human body. Due to the renewable cellulose, our ternary composite ZAC imparts low-cost, easily recycled and flexible merits, which might be applied in the indoor VOCs treatment.

Highly toxic divalent cadmium causes serious environmental issues. To quickly monitor and/or efficiently remove this potentially toxic metal ion as well as to explore its interfacial chemistry with metal oxides, a sulfur and carbon co-doped titania (S/C-TiO 2 ) composite is synthesized via a facile sol-gel method with the assistance of sodium lignosulphonate (SLS). The prepared composite displays a well-crystallized TiO 2 nanostructure comprising the anatase phase. Both S and C, which are derived from the SLS template, are found to enter the TiO 2 lattice. The S/C-TiO 2 composite exhibits a porous structure with a wide pore size distribution. The newly synthesized composite shows adsorption capability for the potentially toxic metal Cd(II). The adsorption process requires <5 min to reach equilibrium. The measured equilibrium adsorption capacity is 19.42 mg g −1 , which is twice as high as that of bare TiO 2 . The removal efficiency is as high as 97%. Moreover, the materials are suitable for contaminated solutions over a wide range of pH values and various initial cadmium concentrations. A mechanism for the enhanced adsorption behavior is also proposed.