Search

This study provided a new idea for the preparation of magnetic nanoparticles using organic rectorite as a carrier, and a novel magnetic adsorbent, chitosan/organic rectorite-Fe 3 O 4 composite microspheres (CS/χOREC-Fe 3 O 4 ), was synthesized. The structure and physical properties of CS/χOREC-Fe 3 O 4 were characterized by XRD, SEM, TEM, FT-IR, TG, M s and XPS and its adsorption properties for removal of 3 mg/L heavy metal ions under different conditions were also investigated. The results showed that the CS/χOREC-Fe 3 O 4 microspheres exhibited excellent adsorption capacity for removing metal ions compared with the corresponding OREC-Fe 3 O 4 or chitosan alone. The adsorption process was fitted to Langmuir model and pseudo-second-order kinetic model. The E a and ΔG revealed that the adsorption of Cu (II) and Cd (II) proceeded with a low potential energy and all the adsorption processes were spontaneous. Further recycle experiments exhibited the adsorption capacity of adsorbent still maintained above 55% after the 4th cycle. All results implied that CS/χOREC-Fe 3 O 4 could be used as a promising adsorbent. [ABSTRACT FROM AUTHOR]

Chitosan/rectorie (CTS/REC) nano-hybrid composite microsphere was prepared by changing the proportion of CTS/REC with 2:1, 3:1 and 4:1. Compared with the pure cross-linking chitosan microsphere, the nano-hybrid composite microsphere was proved to have better sorption capacity of Cd(II), Cu(II) and Ni(II), especially 2:1(CTS/REC-1). The adsorption behavior of the microsphere of Cd(II), Cu(II) and Ni(II) was investigated in single and binary metal systems. In single system, the equilibrium studies showed that the adsorption of Cd(II), Cu(II) and Ni(II) followed the Langmuir model and the pseudo-second-order kinetic model. The negative values of (Δ G ) suggested that the adsorption process was spontaneous. In binary system, the combined action of the metals was found to be antagonistic and the metal sorption followed the order of Cu(II) > Cd(II) > Ni(II). The regeneration studies indicated that EDTA desorbed Cd(II), Cu(II) and Ni(II) from cross-linking microspheres better than HCl. The FT-IR and XPS spectra showed that coordination bonds were formed between Cd(II), Cu(II) and Ni(II) and the nitrogen atoms of cross-linking CTS/REC nano-hybrid composite microspheres. [ABSTRACT FROM AUTHOR]

In this study, magnetic particles were prepared using organic rectorite as a carrier, and then a novel magnetic adsorbent named chitosan/organic rectorite-Fe 3 O 4 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 Δ G , Δ H , and Δ S 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. [ABSTRACT FROM AUTHOR]