Matrix optimisation for hazardous organic waste sorption

Organophilic clays have proven to be interesting intermediates for the definitive stabilization of hazardous organic waste in cement matrix. In the present work, the influence of quaternary ammonium salt structure on the organophilic clay load capacity and the interaction type with the organic waste were investigated. Commercial organophilic montmorillonite clays, containing an ammonium quaternary salt with methyl and long chain aliphatic groups or both aliphatic and aromatic (benzyl) groups, were selected for the experiments. X-ray diffraction (XRD) and FT-IR spectroscopy were used to investigate the pollutant–organoclay interactions. An aromatic amine, i.e. 2-chloroaniline, was chosen as a model pollutant. Sorption isotherms, on organoclays exchanged with ammonium quaternary salts containing the aromatic group, showed a significant increase of the sorbed waste quantity in comparison with those obtained from ammonium quaternary salts with aliphatic groups. The distribution coefficient Kd, estimated on the basis of experimental data, could be explained with dispersive interactions, partially reversible, as resulted from the leaching experiments carried out after sorption process.