The preparation and thermal properties of chitosan/bentonite composite beads

The biopolymer composites are often used as remarkable adsorbents in treatment of wastewater due to their biodegradable and nontoxic nature. The chitosan/bentonite composite beads, in this study, were obtained by addition of clay into the polymer using solution process. The bentonite was modified with surfactant cetyltrimethyl ammonium bromide (CAB) before the composite preparation. The morphology of beads was examined by scanning electron microscopy (SEM). Thermal properties of the composite beads were studied by simultaneous thermogravimetry coupled with differential scanning calorimetry (SDT) and differential scanning calorimetry (DSC). TG results showed that the complex decomposition mechanism of the composites depends on the preparation procedure. It was observed that the concentration of NaOH used for composites precipitation affects the final structure of beads. The influence of preparation procedure on the glass transition temperature Tg of chitosan/bentonite samples was not found (Tg values for all samples were about 144 degrees C).