Influence of Magnetic Field on Adsorption of Polyacrylic Acid (PAA) on SiO2

Resumo

The aim of this study was to investigate the influence the magnetic field on the adsorption of polyacrylic acid (PAA) on the silica (SiO₂) surface as well as on the zeta potential of the PAA/SiO₂ system. The magnetic field influences the amount of PAA adsorbed on silica. The highest adsorption of PAA was observed at pH 9 and the lowest at pH 3. This tendency is opposite to that for the adsorption of PAA on SiO₂ in the absence of the magnetic field. This discrepancy occurs because magnetic field generates dipoles in the polymer macromolecules due to the presence of delocalized electrons in the ionized carboxylic groups. Consequently, the PAA molecules undergo polarization, which implies their adsorption on the negatively charged surface of silica. It was also observed that the magnetic field influences the zeta potential of the PAA/SiO₂ system by changing the conformation of the adsorbed macromolecules accompanied by changes in the position of the slipping plane.