Preparation of ion-exchangeable nanobeads using suspension polymerization and their sorption properties for indium in aqueous solution

Abstract

Poly(vinylphosphonic acid-co-acrylic acid) nanobeads were synthesized using suspension polymerization, and their indium sorption properties were investigated. In the first part of this study, the nanobeads were prepared using suspension polymerization and the obtained nanobeads were characterized using Fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA) and scanning electron microscopy (SEM). Both the synthetic yield and ion-exchange capacity decreased and the water uptake increased with increasing vinylphosphonic acid (VPA) content. In the second part of the study, the sorption isotherms and thermodynamics of the sorption process were investigated. The maximum sorption predicted using the Langmuir sorption isotherm model was the greatest at a 0.5 molar ratio of VPA; therefore, the optimum conditions for the preparation of the nanobeads were a VPA-to-acrylic acid (AA) molar ratio of 0.5. The thermodynamic parameters (ΔGo, ΔHo and ΔSo) were calculated from the temperature-dependent sorption isotherms and indicate that the sorption process was spontaneous.