Using microwave irradiation as an intercalation method, quaternized chitosan/ organo – montmorillonite (QCS/OMMT) nanocomposites were prepared rapidly by intercalating quaternized chitosan (QCS) into the interlayer of organo – montmorillonite (OMMT) in 70 min. The structure and morphology of QCS/OMMT nanocomposites were characterized and their flocculation behavior was evaluated. FT – IR, XRD, TEM and zeta – potential results showed that QCS molecules and silicate layers of OMMT were connected by hydrogen bonds and electrostatic interaction, and the interlayer distances of all QCS/OMMT nanocomposites obtained by this microwave irradiation method were larger than those obtained by the conventional heating method, the largest interlayer distance reached 4.24 nm when the weight ratio of QCS to OMMT was 2:1. TGA results suggested that the thermal stability of the nanocomposites was higher than that of QCS. The flocculability of QCS/OMMT nanocomposites was evaluated by adding the nanocomposites into CaCO3 suspensions. Results showed that an optimum flocculability concentration of QCS/OMMT nanocomposites was only 0.005 mg/L, which was much lower than 15 mg/L of the common flocculant--cationic starch, indicating excellent flocculability of QCS/OMMT nanocomposites. In summary, microwave irradiation method was found to be a promising tool for preparing chitosan – based layered silicate nanocomposites, and the nanoocmposites showed excellent flocculating activity.
Keywords: Quaternized chitosan, organo-montmorillonite, nanocomposites, microwave irradiation, flocculation behavior, thermal stability, intercalation method
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