New adsorbents from Ti(OPrn)4 by the sol-gel process: Synthesis, characterization and application for removing some heavy metal ions from aqueous solution

New adsorbents were synthesized by the sol-gel process from the product of a hydrolysis reaction and its coated form of titanium(IV)-n-propoxide for removing some heavy metal ions from aqueous solution. Titanium(IV)-n-propoxide was uncatalyst hydrolyzed with different amounts of water at room temperature and was found to react in a 1:1.6 ratio (mole of Ti:mole of H2O). It was found that the condensation following the hydrolysis reflection was alcohol condensation. The hydrolysis-condensation product was characterized in detail by GC. Karl-Fischer coulometric titrator, NIR-spectroscopy, FT-IR spectroscopy, TG-DTA and elemental analysis. The hydrolysis-condensation product of titanium(TV)-n-propoxide was calcinated at 900degreesC after drying at 100degreesC and some of this product was coated with hydrolyzed NH2-functional silanes [3-(2-aminoethylamino)ethylamino)propyl-trimethoxy silane] (Amino-and [3-(2-aminoethylamino)propylmethyldimetoxysilane] (Amino-2), separately. Adsorption capacities of uncoated and NH2-functional silane coated hydrolysis-condensation products for Fe3+, Cu2+ and Pb2+ ions in aqueous solution were investigated by FAAS. It was observed that the extent of adsorption was influenced significantly by the type and concentrations of coating materials, e.g., Amino-1 coated adsorbent prepared in methyl alcohol as 50% (w/w) and 100% (without methyl alcohol) adsorbed 90-67% and 100% of Fe3+, respectively. while the uncoated form adsorbed only 5%. The adsorption isotherm was determined and the data were analyzed according to the Freundlich model.