Abstract
A robust sol-gel process was developed for the synthesis of surface-functionalized titania nanocrystallites bearing unsaturated groups starting from molecular heteroleptic single-source precursors. Molecules and nanomaterials were thoroughly characterized by multinuclear liquid and solid-state nuclear magnetic resonance (NMR), infra-red (FT-IR, DRIFT) spectroscopies. Nitrogen adsorption-desorption (BET), thermogravimetric (TG) and elemental analyses demonstrated the reliability and the fine tuning of the surface functionalization in terms of ratio TiO2:ligand. The as-prepared materials were used as nano-adsorbents to remove mixture of 16 polycyclic aromatic hydrocarbon (PAHs) from aqueous solutions. Adsorption kinetic experiments were carried out for 24 h in solutions of one PAH [benzo(a)pyrene, 220 ppb] and of a mixture of sixteen ones [220 ppb for each PAH]. Most kinetic data best fitted the pseudo-second order model. However, in PAHs mixture, a competition process took place during the first hours leading to a remarkable high selectivity between light and heavy PAHs. This selectivity could be fine-tuned depending on the nature of the unsaturated group of the phosphonate framework and on the nanomaterial textures.
Highlights
Polycyclic aromatic hydrocarbons (PAHs) are a family of nonpolar neutral chemical compounds resulting from the condensation of several benzene rings ranging from two to three, to four and five and up to seven
We report the synthesis, characterization and properties of new hybrid nanotitania supports functionalized with a series of organophosphorus molecules (R–OPO2 H2 ) holding different unsaturated groups (R = vinyl, phenyl, naphtyl) and spacers
This was confirmed by doubling the volume of PAH aqueous solution, using solution, using 100 mL batches of 200 ppb PAH solution with 10 mg of the materials, whereupon the
Summary
Polycyclic aromatic hydrocarbons (PAHs) are a family of nonpolar neutral chemical compounds resulting from the condensation of several benzene rings ranging from two to three (light molecular weight PAHs, LMW PAHs), to four and five (medium molecular weight PAHs, MMW PAHs) and up to seven (heavy molecular weight PAHs, HMW PAHs). Studies dealing with the influence of the nature of the trapping organic molecule on adsorption properties towards PAH selectivity or affinity in mixture of LMW and HMW ones are scarce. We report the synthesis, characterization and properties of new hybrid (in this case organic-inorganic) nanotitania supports functionalized with a series of organophosphorus molecules (R–OPO2 H2 ) holding different unsaturated groups (R = vinyl, phenyl, naphtyl) and spacers. The performances of such π-stacking complexation sites will be compared in terms of selectivity, capacity and kinetic of adsorption in an aqueous mixture of 16 PAH molecules. The Titanium oxide will be our nano-support of choice, because of the simple “soft chemistry” preparation routes of crystallized nanoparticles of titanium oxide widely studied in the literature and in our laboratory [13]
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