p-phenylenediammonium-smectites as adsorbents with colorimetric detection ability for phenols in water

The ion exchange of p-phenylenediammonium and sodium-smectites (montmorillonite and synthetic saponite) resulted in the formation of p-phenylenediammonium radical cation and its dimer by the electron transfer from p-phenylenediammonium to smectites, as revealed by the color change (from colorless to green) as well as the visible absorption spectra. The p-phenylenediammonium-saponite thus obtained adsorbed phenols from aqueous solutions. The basal spacing of the p-phenylenediammonium-saponite increased upon the uptake of phenols, indicating a change in the microstructure. The uptake of phenols into the p-phenylenediammonium-saponite from aqueous solutions occurred through the formation of indoaniline dyes, as revealed by the color change from green to purple (for phenol) or purple-blue (for 2,4-dichlorophenol) as well as the absorption spectra. On the contrary, phenols were not intercalated into the interlayer space of the p-phenylenediammonium- montmorillonite.