Resumo

MENDOZA-REYES, León G. et al. Novel D2EHPA-polysiloxane-based Sorbent for Titanium (IV) Extraction and Separation. J. Mex. Chem. Soc [online]. 2011, vol.55, n.2, pp.72-78. ISSN 1870-249X.

In this work the synthesis, characterization and evaluation of a novel sorbent material used for the solid-phase extraction of titanium (IV) from hydrochloric acid medium is described. The material was prepared by the sol-gel route incorporating bis(2-ethylhexylphos-phoric acid) (D2EHPA) as extractant within a polymeric matrix based on polysiloxanes and characterized through FTIR-ATR, XRD, ²⁹Si and ³¹P NMR, TGA and DSC. In studies of titanium sorption and desorption in batch mode several factors related with the extraction and back-extraction operations were evaluated, such as: contact time, titanium concentration, nature and composition of the aqueous media, and extractant concentration in the sorbent. The maximum sorption was observed at 30 min of contact time in a 1 mol L^-1 HC1 + 0.1% KC1 medium, while the maximum desorption was observed at 60 min in a 1.5 mol L^-1 H₂SO₄ + 20% v/v H₂O₂ medium when titanium concentration was 70 mg L^-1. Under optimal conditions the recovered percent of titanium was nearly 90%. In addition, the characterization of the extraction equilibrium was performed. The selectivity of the method was studied adding Al(III), Fe(III) and V(V) to the extraction medium. A high selectivity for Ti over Al and Fe was observed, even at high concentrations of the interferents; 50% of Ti, only 7%o of Fe, 3% of Al and less than 1% of V were recovered under the established conditions. The method was finally applied for titanium recovery from a certified fly ash sample generated from a municipal incineration plant.

Palavras-chave : titanium (IV); solid-phase extraction; polysiloxanes.