Ex Cathedra Immobilization of 8-Hydroxyquinoline to Inorganic Carriers via a New Silane Coupling Reagent for Extractive Sample Cleanup of Iron(III)

摘要

By the use of a new silane coupling reagent, dimethyldichlorosilane (DMDCS), effective and instantaneous immobilization of 8-hydroxyquinoline (HQ) on an inorganic carrier (silica gel, SG) has been carried out for the facile synthesis of an extractor material (composition: {Si(OSi)(p=4)(H2O)(x=0.16)}(n=11)[-Si(CH3)(2)-NH-C6H4-N-N-HQ](z=4)25H(2)O; molar mass: 4010.3 g/mol). The material (thermal stability: <= 100 degrees C; chemical stability: <= 8 M HNO3) possesses a high Brunauer-Emmett-Teller surface area (BET-SA(Fe(III)): 1170 m(2)g(-1)), an appreciable preconcentration factor (PFFe(III) 145.1), and high breakthrough capacity (BTCFe(III) column exchange capacity, 269 mu molg(-1); Langmuir Q(0), 278.6 mu mol.g(-1)) for Fe(III). Along with these discernible analytical qualities, a high level of reusability (<800 cycles @ 95% recovery) reflects the material warranty. Fe(III), present as [Fe(OH)(H2O)(5)](2+) at the recommended pH (1.90 +/- 0.15), binds at the highest occupied molecular orbital (HOMO) of the sorbent (eta = 7.69 eV) through hardsoft binding with an appreciable binding energy (-14.2 eV). The breakthrough capacity (BTC 269278.6 mu molg(-1)) was found to be the product of the amount of extractor HOMO (280 mu molg(-1)) and the degree of polymerization of the adsorbed metal ion, x (i.e., BTC = [amount of HOMOextractor (mu molg(-1))] x x for monomeric (x = 1) and polymeric (x > 1) species). The findings reveal substantial improvement of Weetall-Hill immobilization of chelating ligands on inorganic carriers.