Effect of pH on the Viscosity of Titanium Dioxide Aqueous Dispersions with Carboxylic Acids

Abstract

Dispersions of titanium dioxide nanoparticles with terephthalic acid, isophthalic acid, salicylic acid, benzoic acid, and pyridine-2,5-dicarboxylic acid were prepared by aqueous grinding. The pH of the dispersions was adjusted by adding either HCl or NaOH, and the viscosity of the dispersions was measured. It was found that the viscosity of the system depends strongly on pH. The qualitative interpretation of the results based on the DLVO theory is presented. The evidence of the effect of bridging interactions on the viscosity of titanium dioxide-dicarboxylic acid dispersions is discussed.

Anatase nanoparticles surface modified with fused ring salicylate-type ligands (1-hydroxy-2-naphthoic acids): A combined DFT and experimental study

“…Tunesi and Anderson [18,23] claim that no adsorption was observed, while others [10,22,24,40] confirm the formation of bidentate chelate or bridging complexes, pointing out evidence of weak adsorption [22,40]. According to our FTIR results (spectra not presented) obtained for TiO 2 with benzoic acid added, we may conclude that, in the case of benzoic acid, binding through the carboxylate group does not exist.…”

“…In a typical TG-MS experiment, the sample was initially purged with gas at 30°C for 30 min and then heated at 10°C min À1 , up to 600°C. Along this temperature increase, the mass spectrometer was programmed to collect all masses characteristic for O 2 (m/z = 32, 16), H 2 O (m/z = 18, 17, 16) and CO 2 (m/z = 44, 28,22,16,12).…”

“…Ring frequencies m(C@C) are also affected by the new environment, indicating that the formation of the inner-sphere complex changes the electron distribution and symmetry of the ring [71]. It is reported that the charge transfer complex formed may be a bidentate mononuclear chelate and/ or a bidentate binuclear bridging complex [18][19][20][21][22][23][24]40,66,69,72].…”

“…In the last two decades, the surface modification of commercial TiO 2 (Degussa P25, d $ 30 nm) with benzene derivatives mainly catechol [11][12][13][14][15][16][17] and salicylic acid [18][19][20][21][22][23][24] has been studied. Several papers have investigated CT complex formation between catecholate [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] and salicylate [27,[36][37][38]40,41] type ligands and colloidal TiO 2 nanoparticles (d $ 45 Å), where the binding of modifiers induces the surface reconstruction of the nanoparticles.…”

Interactions between oligopeptides and oxidised titanium surfaces detected by vibrational spectroscopy

“…It has to be recalled that the main coordination modes of carboxylate groups in metal complexes are unidentate, bidentate chelating and bidentate bridging. [28] These coordination modes can be distinguished on the basis of the νCOO − value. In unidentate metal-carboxylate complexes, ν is higher than for the corresponding ionic species; bidentate complexes typically exhibit ν lower than those observed for unidentate complexes; and, in particular, for bidentate bridging complexes ν is close to the values found for ionic carboxylates, while being even lower for bidentate chelates.…”