Sorption of aminonaphthalene and quinoline on amorphous silica

The sorption of quinoline and aminonaphthalene from aqueous solution on porous and nonporous amorphous silica was investigated. Amorphous silica was not a strong adsorbent of either compound; quinoline was adsorbed more strongly than aminonaphthalene. The adsorption of both compounds varied with pH, and temperature effects were significant, suggesting enthalpy contributions in the range of hydrogen bonding. The greater basicity of quinoline combined with the enhanced electron-donating priperties of the heteroatom nitrogen and the delocalized pi-bonded ring system were proposed to account for its stronger adsorption.