Poly(p-phenylenediamine)/maghemite composite as highly effective adsorbent for anionic dye removal

Poly(p-phenylenediamine)/maghemite (PPDA/γ-Fe2O3) composites were prepared by the oxidative polymerization of p-phenylenediamine with ammonium peroxodisulfate as an oxidizing agent in the presence of γ-Fe2O3 nanoparticles. Morphology of the prepared composites was examined by the scanning and transmission electron microscopies. X-ray diffraction and EDX were used to study crystallinity and chemical composition, respectively. TGA demonstrated that only 7 and 45 wt% of γ-Fe2O3 were incorporated into PPDA prepared with 25 and 50 wt% of γ-Fe2O3, respectively. Adsorption property of the composites was examined towards the anionic dye, Reactive Black 5. The adsorption results were fitted to different kinetics and isotherm models. The highest adsorption capacity (Qmax) was estimated to be 223 mg g−1 in case of PPDA with the highest specific surface area (70.6 m2 g–1) prepared with 25 wt% of γ-Fe2O3. Qmax of neat PPDA was estimated to be 185.2 mg g−1 and 123.2 mg g−1 for PPDA prepared with 50 wt% of γ-Fe2O3. In addition to the enhancing of the adsorption capacity, the incorporation of γ-Fe2O3 particles provided an easy separation of the composites from the adsorption medium.