Synthesis, characterization, morphology and adsorption performance towards Cu +2 ions of nano-sized homopolymers of o -aminophenol poly( o -AP)

Nanostructures with different particles size of homopolymer o-aminophenol poly(OAP) were synthesized by redox polymerization initiated by FeSO4.7H2O as redox initiator and ammonium peroxydisulfate (APS) as an oxidant in different concentrations of aqueous solutions of hydrochloric acid. The influence of synthetic parameters such as acid concentration and the presence of redox initiator were investigated. The morphology and particles size were studied by transmission electron microscope (TEM) and scanning electron microscope (SEM). The results showed that the morphology and average particle size of polymeric nanoparticles according to SEM and TEM analyses were different based upon the conditions of the polymerization. It can be seen that 0.1 M and 0.5 M of HCl in the presence of FeSO4.7H2O showed nanospheres with average diameters 63.71 nm and 84.66 nm, respectively. However, poly(OAP) of nanospheres with the average diameter of 106.66 nm were obtained by the same method except that the polymerization was carried out in the dark. Finally, the last condition of polymerization in the absence of redox intiator (FeSO4) at 0.1 M HCl, it appeared as nanoreef structure with average diameter of 153.33 nm. The physico-chemical characterization of the prepared nanoparticles was carried out by Fourier transform infrared spectroscopy (FT-IR) and X-ray powder diffraction (XRD). Which FT-IR confirmed the structure of poly(OAP) nanoparticles in emeraldine form. The molecular weight was determined by gel permeation chromatography (GPC). The surface area of nanopolymer particles was determined also by Brunauer–Emmett–Teller (BET). The competition of the prepared nano-sized homopolymers particles towards the adsorption of copper ions from aqueous solutions was investigated. The results showed that the adsorption capacity was based on particle size of nanopolymers and their surface area. The adsorption capacity increased with decreasing the particle size. On the other hand the adsorption capacity increased with increasing the surface area of the prepared nano-sized homopolymers of poly(OAP). Which the nano-sized of poly(OAP) of particle size 63.71 nm had the highest adsorption capacity of Cu+2 ions with 60.4 mg/g