A facile method was developed for preparing size-controlled silver nanoparticles supported by pyrolytic carbon from microcrystalline cellulose (MCC). The pyrolysis of cellulose-AgNO₃ mixture caused the oxidation of cellulose, resulting in carboxyl groups to which silver ions can bind firmly and act as nuclei for the deposition of silver nanoparticles. The structure and properties of the obtained nanocomposite were characterized by using a scanning electron microscope (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) and X-ray diffraction (XRD). The results suggest that silver nanoparticles were integrated successfully and dispersed uniformly in the pyrolytic carbon matrix. The average particle size varied between 20 nm and 100 nm in correlation to the dose of silver nitrate and temperature of pyrolysis. The products showed high electric conductivity and strong antimicrobial activity against Escherichia coli (E. coli).

Fe-Al (hydr)oxide nano-/micro-particles were well grown and dispersed on a wheat straw template, which was characterized by a scanning electron microscope (SEM) with energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and a vibrating sample magnetometer (VSM). The adsorption mechanism of the biomass-based Fe-Al (hydr)oxide nanocomposite was studied by the adsorption isotherms, which followed the Langmuir model better than the Freundlich and Temkin models. In particular, a synergistic adsorption by the mixed Fe-Al (hydr)oxide nano-/micro-particles based on the wheat straw was found, with higher maximum adsorption capacity (Q₀) than that of the material containing only Fe₃O₄ or Al(OH)₃ nano-/micro-particles, which was most obvious when the mole ratio of Fe to Al was 1:1. The degree of this unusual effect was reasonably determined by the departure between the experimental and calculated maximum adsorption capacity (Q₀-Q₀(cal)), which showed that the synergistic effect was most pronounced when the mole ratio of Fe to Al was approximately 1:1. The good adsorption capacity of the mixed Fe-Al (hydr)oxide nano-/micro-particles and the good dispersity by the wheat straw matrix were combined in the biomass-based Fe-Al (hydr)oxide nanocomposite. The nanocomposite material showed high adsorption capacity for both fluoride (F^-) and arsenic (As(Ⅲ) and As(Ⅴ)), and had the advantage of magnetic separation by tuning its compositions.