Sorption of benzene derivatives onto a humic acid-zeolitic tuff adduct.

The sorption of some benzene derivatives: o-xylene, toluene, phenol, benzyl alcohol, resorcinol and hydroquinone onto a zeolitic tuff-humic acid adduct (PCT-ImHA) was analysed by batch technique at 25 °C and neutral pH. PCT-ImHA was prepared by binding leonardite-extracted humic acids (HA) to a zeolitic tuff sample rich in phillipsite and chabazite and enriched with Ca2+ by cation exchange (Ca-PCT). The HA calcium salts were gently mixed with wet Ca-PCT; then, the mixture was heated at 330 °C for 1.5 h. An adduct with almost 2% of HA was obtained. The experimental data were well fitted by the Langmuir adsorption isotherm and showed that saturation capacity (qMax) increased with the octanol-water repartition coefficient (KO-W). The comparison with previous data on sorption onto immobilised HA highlights that qMax values for PCT-ImHA are far higher than the sum of the contributions of the two separate components.