Adsorption of cationic ‘gemini’ surfactants at the TiO₂/solution interface

Abstract

Adsorption isotherms of cationic pyridinium surfactants at the solid/liquid interface were obtained on aqueous dispersions of titanium dioxide as a function of the electrification features of the adsorbent. The surfactants, prepared in the laboratory, were a symmetric 'gemini-like' dimer (1,1 -bidodecyl-4,4 -bipyridinium chloride) and its related simple monomeric salt (1-dodecyl-4-methylpyridinium chloride). X-ray photoelectron spectroscopy analyses were performed both on the bare adsorbent and in the presence of the adsorbates. The XPS regions of Ti 2p, O 1s, N 1s and C 1s were specifically investigated. The nature of the interactions supporting the adsorption and the molecule orientation/co-area are discussed in the light of the different experimental evidence.

Growth of TiO2 nanocrystals in the presence of alkylpyridinium salts: the interplay between hydrophobic and hydrophilic interactions

“…Results from XPS characterization, although performed in ex situ conditions, are reported to closely match the adsorption data from solution, 12 -15 and in the case of organic adsorbates the analysis of the C 1s peak structure offers precious indications concerning the features of the adsorption. 13,14 The spectra of a pure TiO 2 precursor, aged at pH 8 in the absence of the surfactant, and of the pure DPC and CPC salts have also been obtained for the sake of comparison.…”

Surface Stabilization of Nano-sized Titanium Dioxide: Improving the Colloidal Stability and the Sintering Morphology

“…The O 1s core-level spectra of as precipitated UMP and SMP are shown in Figure 7a and b. The main peak (A) binding energies of 530.25 eV for UMP and 529.69 eV for SMP are within the range that is characteristic of metal oxides (Moulder et al, 1992) and specifically for O 1s in TiO 2 (Babelon et al, 1998;Ardizzone et al, 2002). Therefore, peak A may be assigned with O in TiO(OH) 2 .…”

“…The regions of C 1s, O 1s and Ti 2p were specifically investigated with 0.05 eV energy step and ±0.05 eV accuracy. The obtained binding energies were compared to values from Handbook of X-ray Photoelectron Spectroscopy (Moulder et al, 1992) and to values that were reported in the literature (Wu et al, 2000;Go¨pel et al, 1984;Babelon et al, 1998;Ardizzone et al, 2002;Morris et al, 2000).…”

“…Peak C is of Ti in TiO(OH) 2 . Ti 2p 3/2 binding energies vary quite significantly, depending on the preparation procedure (Wu et al, 2000;Go¨pel et al, 1984;Babelon et al, 1998;Ardizzone et al, 2002). The binding energies, characteristic of TiO 2 , are in the $458.6-459.2 eV range (Moulder et al, 1992).…”

Contribution of 1H NMR to the investigation of the adsorption of cationic Gemini surfactants with oligooxyethylene spacer group onto silica

“…Moreover, the adsorption studies concerned mainly gemini surfactants with a polymethylene spacer, referred to as 12-s-12, [13][14][15][16][17][18][19][20]. The lack of such studies has hindered progress in the application of gemini surfactants to the formulation of solidliquid dispersions, mineral flotation, pollutant removal and other industrial processes [21][22][23].…”