Abstract
► The m-CS/PVA HBs were prepared with inter- and intra-hydrogen bonds between chitosan and PVA. ► The adsorption capacity of Congo Red on the m-CS/PVA HBs was 470.1
mg
g
−1. ► The adsorption was endothermic in nature. ► The m-CS/PVA HBs could be employed as a low-cost alternative to other adsorbents. ► The m-CS/PVA HBs could be easily removed with an addition of a permanent magnet.
Novel magnetic chitosan/poly(vinyl alcohol) hydrogel beads (m-CS/PVA HBs) were prepared by an instantaneous gelation method and characterized by X-ray diffraction (XRD), vibrating sample magnetometry (VSM) and thermogravimetric analysis (TGA). Results of characterization indicated that m-CS/PVA HBs have been prepared successfully without damaging the crystal structure of Fe
3O
4 and their saturation magnetization were about 21.96
emu
g
−1. The adsorption capacity of Congo Red on the m-CS/PVA HBs was 470.1
mg
g
−1. The adsorption was well described by pseudo-second-order kinetics and Langmuir equation. Positive value of enthalpy change
(
Δ
H
∘
)
(13.32
kJ
mol
−1) showed that the adsorption was endothermic and physical in nature. The values of Gibbs free energy change
(
Δ
G
∘
)
were found to be −3.321
kJ
mol
−1 at 298
K for m-CS/PVA HBs, indicating the spontaneity of Congo Red adsorption. Therefore, the m-CS/PVA HBs could be employed as a low-cost alternative to other adsorbents in the removal of dyes from aqueous solution.