RESUMO
In this study, magnetic particles were prepared using organic rectorite as a carrier, and then a novel magnetic adsorbent named chitosan/organic rectorite-Fe3O4 intercalated composite microspheres (CS/Mt-OREC microspheres) was synthesized. The microspheres were characterized by XRD, FT-IR, TEM, SEM and VSM. The effects of adsorbent dosage, initial pH, contact time, temperatures, initial concentrations of methylene blue (MB) and methyl orange (MO) were studied. The adsorption process followed the pseudo-second-order kinetics, and the intra-particle diffusion was one but not the only rate-limiting step. The adsorption equilibrium data can be well described by Langmuir model. Thermodynamic parameters such as ΔG, ΔH, and ΔS were estimated to understand the adsorption mechanism of dyes. Moreover, CS/Mt-OREC microspheres were successfully regenerated using NaOH and HCl, and could be easily separated from aqueous solution in magnetic field.
RESUMO
Silver nanoparticles (Ag NPs) were synthesized rapidly in one pot via the Tollens reaction, in which quaternized chitosan (QCS) and rectorite (REC) acted as the reducing and stabilizing agent, while other chemical reducing and stabilizing agents and the surfactant were not included. X-ray diffraction, scanning electron microscopy and transmission electron microscopy results showed that spherical Ag NPs with uniform sizes were obtained, the layers of clay were peeled and thus exfoliated QCS/REC/Ag NP (QCRAg) nanocomposite was achieved. Moreover, Ag NPs dispersed well in the exfoliated nanocomposite matrix, some Ag NPs even entered into the interlayer of REC. QCRAg nanocomposites showed strong antimicrobial activity; the lowest minimum inhibitory concentration against Staphyloccocus aureus was only 0.0001% (w/v). The study reveals that the obtained QCRAg nanocomposites have great potential for biomedical applications.
