| Environmental pollution caused by heavy metal ion in industrial wastewater hasaroused more and more people′s attention. Chitosan and its derivatives have widelybeen used in water treatment due to abundant resources, environmental-friendlycharacter and efficient adsorption capacity. In this paper, using chitosan as thesubstrate, a variety of methods were adopted to improve its strength and copper ionsadsorption properties.The crosslinked chitosan (CCTS), polyacrylamide/chitosan (PAM/CTS),chitosan/ZSM molecular sieve (CTS/ZSM) and chitosan/Y molecular sieve(CTS/Y) composite were prepared under microwave radiation. These compositeswere characterized with FTIR, TGA, XRD and Super field depth3-Dmicroscopy. The adsorption properties of copper ions onto these samples weredetailed studied. It was showed that compared with CCTS, the PAM/CTS, CTS/ZSM,CTS/Y had more great Cu (Ⅱ) adsorption capacity. The adsorption capacity of Cu (Ⅱ)onto CCTS, PAM/CTS, CTS/ZSM and CTS/Y decreased with the increase of theamount of crosslinking agent.When the ratio of PAM/CTS was0.3/0.5, the adsorption capacity of Cu (Ⅱ) ontoPAM/CTS reached the maximum. When the content of Y molecular sieve was6%andthe content of ZSM molecular sieves was4%, CTS/Y and CTS/ZSM hadthe maximum adsorption capacity.It was shown from kinetic studies that the pseudo-second order kinetic equationwas well fitted to copper ion adsorption to CCTS and PAM/CTS. Otherwise thepseudo-second order model could not explain the adsorption of Cu (II) onto CTS/Yand CTS/ZSM composites. For the whole adsorption process of CCTS, PAM/CTS,CTS/Y, CTS/ZSM, the intra-particle diffusion model was the main limiting step.Thermodynamic study showed that the Langmuir isotherm model gave better fits tocopper ions adsorption onto CTS, CCTS, PAM/CTS, CTS/Y and CTS/ZSM. Theadsorption of Copper ions on these samples was all favorable.Due to introduction of crosslinking structure and ZSM molecular sieve, chitosanmatrix had weakening ability of crystallization and low crystallization degree. And thethermal stability of CTS was improved. CTS/ZSM composite had certain reusability.Polyurethane/chitosan resin (PU/CTS) and chitosan/methyl cellulose/bentonitecomposite microspheres (CTS/MC/BC) were prepared using simple process. The adsorption properties of copper ions were investigated in detail. It was showedthat PU/CTS had rough surface and did not dissolve in acid, neutral and alkalinemedium. The Cu (Ⅱ) adsorption capacity of PU/CTS decreased with the increase ofPUP content. And the calculated adsorption capacity of copper onto unitCTS reached maximum when the ratio of PU/CTS was1:1.CTS/MC/BC microspheres had uniform size and rough surface. The adsorptioncapacity of copper on CTS/MC/BC has been improved because of adding of MC andBC and the optimal proportion was0.45gCTS/0.05gMC/15%BC. The pseudo-secondorder kinetic equation and Langmuir isotherm equation can be well fitted to copperion adsorption on PU/CTS and CTS/MC/BC. For the whole adsorption process,copper adsorption onto PU/CTS was controlled by intra-particle diffusion and copperadsorption onto CTS/MC/BC was controlled by liquid film diffusion. |
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