Synthesis and characterization of polybenzimidazole/silica nanocomposites

In this study, thermal and morphological properties of montmorillonite polybenzimidazole composite (MMT/ABPBI) were primarily investigated. The morphology and structure of MMT/ABPBI composites were characterized by Fourier transformed infrared spectrometer (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA-DTG) techniques. At low MMT loading, exfoliation was the predominant mechanism of MMT dispersion. At high MMT loading, non-intercalated microcomposite morphology was partially favoured in expense of the intercalated nanocomposite. Thermal degradation of nanocomposite occured in three stages with various mass percent losses. In the second stage of thermal degradation, the onset temperature of degradation for the MMT/ABPBI nanocomposites was lower than that of ABPBI polymer. In the last stage, the improvement in thermal stability by the introduction of MMT into the ABPBI was different from the second stage. The activation energy for degradation of ABPBI increased from 62,6 kJ/mol to 77,7 kJ/mol after loading of 5 % modified montmorillonite (mMMT) content into ABPBI matrix under air atmosphere. Batch adsorption experiments were carried out for the removal of phosphate species from aqueous solution using poly(2,5-benzimidazole) (ABPBI) as adsorbent. The physicochemical properties of adsorbent were investigated by FT-IR, TGA and SEM methods. The activation energy for degradation estimated by Kissinger method for ABPBI was found to be 29 kJ/mol in static air atmosphere. The effects of initial phosphate concentration, pH and contact time parameters onto the adsorption of phosphate species from aqueous solutions were investigated. The Langmuir monolayer adsorption capacity of ABPBI was calculated as 87,90 mg/g. The Pseudo-first-order, Pseudo-second-order kinetic and the intra-particle diffusion models were used to describe the kinetic data and rate constants were evaluated.