Synthesis of polyamide-6: Characterization and application to the removal of heavy metals by clays

Abstract

Using maghnite as an inorganic reinforcement, polyamide-6-based nanocomposites (PA6/Mag-CTA) have been synthesized. Maghnite is a type of laminar clay, which is distinguished by a significantly higher SiO₂/Al₂O₃ ratio than other clays in the world. It is likely that the interfacial cations of maghnite form active sites during the reaction, and thus give it a catalytic behaviour. This work focuses on the preparation and characterization of polyamide-6/organic clay nanocomposites. The effect of the nature of organo-modified clay, and the preparation method have been studied to assess their structural, morphological and thermal properties, as well as their mechanical properties. Diverses compositions de PA6-Mag-CTA ont été élaborées en intégrant 1, 3, 5 et 7% de Mag-CTA. The formation of polyamide-6 has been confirmed by X-ray diffraction (XRD), spectroscopy (IR), thermogravimetric analysis (TGA), scanning and transmission electron microscopy (TEM,SEM) , atomic force microscopy (AFM). The results obtained provide evidence of intercalation of salt molecules within the clay layers, as well as good interaction with the polymer, showing the presence of intercalated and exfoliated structures. The nanocomposites show better thermal stability compared to virgin polyamide-6, which is examined by thermogravimetric analysis (TGA). An evaluation of the mechanical properties of the nanocomposites is carried out as a function of clay loading and PA6 matrix type. The Young's modulus and yield strength are measured in order to define the mechanical behaviour. PA6 filled with 5% Maghnite has better mechanical performance; this is due to the dispersed state of the Mag-CTA in the PA6 matrix. The improvement of the efficiency of the process adequate to the retention of the maximum of toxic elements and the effects of the initial pH of a solution and the contact time on the adsorption efficiency are studied.