Magnetic Poly(glycidyl methacrylate) Microspheres with Grafted Polypyrrole Chains for the High-Capacity Adsorption of Congo Red Dye from Aqueous Solutions

Abstract

In this study, novel magnetic poly(glycidyl methacrylate) (PGMA) microspheres with grafted polypyrrole chains (magnetic PGMA-g-PPy) were developed for the high-capacity adsorption of Congo red (CR) from aqueous solutions. The magnetic PGMA-g-PPy was synthesized by the typical dispersion polymerization method and the ring-opening reaction of epoxy groups, producing abundant hydroxyls for the grafting polymerization of pyrrole in the presence of FeCl3 as an oxidizing agent on the surface of the microspheres. The characterization results showed that magnetic PGMA-g-PPy was successfully fabricated. The adsorption equilibrium data of the adsorbents could be well fitted by the Langmuir isotherm model, showing a high maximum adsorption capacity of 502.5 mg/g for CR. The adsorption followed pseudo-second-order kinetics with a fast speed. The adsorbents had no leaching of Fe in the solution at pH 1.0–11.0 for 24 h. The adsorption process was strongly pH-dependent and weakly ionic-strength-dependent. Furthermore, the magnetic microspheres could be easily regenerated, rapidly separated from the solution, and reused for wastewater treatment. The results suggest that magnetic PGMA-g-PPy microspheres are a promising efficient adsorbent for the removal of CR from wastewater.