Chemical modification of controlled-pore silica with N-propylsalicylaldimine

Two controlled-pore silica phases were prepared with a sol-gel precursor from a sodium silicate solution. N-Propylsalicylaldimine was immobilized on these silica species to be used as chelating ion exchangers (IE11 and IE2). The monomer phase was also prepared for comparison. The N-propylsalicylaldimine moiety was detected by Fourier transform infrared and ultraviolet in both the ion exchangers and the monomer phases. 1H-NMR and mass spectrometry of the monomer also confirmed the structure. The capacity (C) of the ion exchangers was dependent on the porosity of the ion exchanger (C-1E11 = 0.36 mmol of Cu/g and C-IE2 = 0.026 mmol of Cu/g). The uptake behavior of IE11 toward some metal ions was studied, and log distribution coefficient (k(d)) was within the range of 2.19-5.16. Also, thermogravimetric and differential thermogravimetric analysis data were used to study the kinetics of the thermal decomposition process of IE11. Some thermodynamic parameters for the ion exchanger were calculated by the application of the rate theory of the first-order reaction. (C) 2003 Wiley Periodicals, Inc.