New insights on humic acid-zeolite surface interactions

The sorption ability of humic acids (HA) by zeolitic tuffs has been investigated at neutral pH and room temperature by batch sorption tests, using a phillipsite/chabazite-bearing tuff, a frankly chabazitic tuff and a clinoptilolite-rich tuff, both in the raw and Ca-enriched forms. These latter forms have been obtained by cation exchange at room temperature or by joint cation exchange/thermal treatment. For all the tuffs analyzed, the joint treatment gave rise to samples with higher calcium content and superior sorption ability. Moreover, the sorption capacity was higher for phillipsite-bearing tuff and increased, for all the samples, with the contact time between the solid phase and the humic acids solution, reaching an equilibrium state after several weeks. The Langmuir parameters of the sorption isotherms showed that the phillipsite/chabazite-rich tuff in its Ca-enriched form exhibited after a few days sorption properties better than or at least comparable to those observed for a commercial activated carbon.

The sorption ability of humic acids (HA) by zeolitic tuffs has been investigated at neutral pH and room temperature by batch sorption tests, using a phillipsite/chabazite-bearing, a frankly chabazitic tuff and a clinoptilolite-rich tuff. both in the raw and Ca-enriched forms. These latter forms have been obtained by cation exchange at room temperature or by joint, cation exchange/thermal treatment. For all the tuffs analyzed, the joint treatment gave rise to samples with higher calcium content and superior sorption ability. Moreover, the sorption capacity was higher for phillipsite-bearing tuff and increased, for all the samples, with the contact time between the solid phase and the humic acids solution, reaching all equilibrium state after several weeks. The Langmuir parameters of the sorption isotherms showed that the phillipsite/chabazite-rich tuff in its Ca-enriched form exhibited after a. few days sorption properties better than or at least comparable to those observed for a commercial activated carbon.