Phytic acid-doped polyaniline nanofibers-clay mineral for efficient adsorption of copper (II) ions

Abstract

Polyaniline (PANi)-clay hybrids are an important class of materials in the field of catalysis and adsorption. Owing to their unique structural properties such as self-assembly with functional materials, intercalation and surface functionalization, they have demonstrated to be more efficient candidates for environmental remediation than clay or polyaniline taken separately. Here, we report on the synthesis of phytic acid-doped PANI@montmorillonite (P-PANi@Mt) composite material via radical polymerization by varying the amount of Mt in the composite material. The formation of functional groups is detected by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy and Raman analysis, which is consistent with the anchoring of phytic acid into PANi chains. Furthermore, the BET measurements revealed that the incorporation of Mt reduced the specific surface area of P-PANi-Mt hybrid due to the coating of Mt surface by P-PANi. The obtained materials were assessed for their capacity to adsorb copper (II) ions in aqueous media. Under optimized experimental conditions, P-PANi and P-PANi@Mt1 composites were found to be the most effective materials for Cu2+ ion capture with adsorption capacities of 66.6 mg g−1 and 87 mg g−1, respectively. By increasing the amount of montmorillonite in the composite, the adsorption capacity decreased substantially. This result could be explained by the tendency of clay particles to aggregate in the PANi matrix and therefore hinder the availability of active sites. The adsorption isotherm processes fit well with the Langmuir model and the enhanced adsorption process was ascribed to the existence of plenty of phosphoric acid groups doped to PANi-coated on Mt layers.