Role of TiO₂ Anatase Surface Morphology on Organophosphorus Interfacial Chemistry

Abstract

Optimization of physicochemical properties of TiO 2 anatase for organophosphorus remediation remains challenging. One approach is to use anatase nanofibers, prepared from hydrothermally synthesized titanates. Charge densities and potentials of anatase nanofibers were determined from atomic force microscopy force−curve measurements using the modified Derjaguin, Landau, Verwey, Overbeek theory, which includes roughness and hydration forces, in the pH range 4−9. Calculated values were −0.007 to −0.03 C m −2 and −70 to −150 mV, respectively. In contrast, at neutral pH, the magnitudes of diffuse layer surface charge densities and potentials have a minimum in anatase nanoparticles. These observations and zeta-potential results suggest that nanofiber surfaces are more acidic compared with nanoparticles. This is consistent with nanofibers having ∼3-fold higher adsorption for organophosphorus methyl parathion (pH ≈ 7). The resulting adsorption includes contributions from (1) charge accumulation at local coordination sites caused by the morphological roughness; (2) greater crystallographic nanoscale variations; and (3) active site competition between parent and daughter species. The structural features of nanofibers have potential applications in catalysis and sequestration of organophosphorus compounds.

Application of Reverse Micelle Sol–Gel Synthesis for Bulk Doping and Heteroatoms Surface Enrichment in Mo-Doped TiO2 Nanoparticles

“…The ζ-potential measurements (Figure 5) show that the bare TiO 2 has a Point of Zero Charge (PZC) of 3.6, that is, a value lower than usual for TiO 2 : for instance, Degussa P25 (with particle size between 20 and 40 nm) has a PZC around 6.2–6.9 [43,44]; for pure TiO 2 NPs (with diameter in the range of 14–33 nm), a PZC of 6.8 [45] was reported; Allard et al found a PZC of 6.1 with commercial anatase NPs (with a diameter of ca. 20 nm) [46]; Al-Hetlani et al found a PZC of 5.98 for smaller anatase NPs (around 7.2 nm [47]); and Huijun et al reported a PZC of 6.2 for anatase NPs (5–10 nm) [48]. The much lower value of PZC reported here may be ascribed, rather than to the size of TiO 2 NPs, to the type of synthesis [49,50] that probably favors the formation of a very acidic surface, in agreement with previous work [43].…”

A New Insight into Coating’s Formation Mechanism Between TiO2 and Alendronate on Titanium Dental Implant

“…The topological analysis of the charge density distibution was performed by the Bader’s quantum theory of atoms in molecules [ 54 ] by using AIMALL software (version 17.01.25) [ 55 ]. The (TiO 2 ) 10 nanocluster was used as a model for all possible molecular implant surface/alendronate interaction predictions [ 56 , 57 ]. Detail description of the modeling, as well as results ( Tables S1–S4 ), are given in Supplementary Materials .…”

Bioactive Coating on Titanium Dental Implants for Improved Anticorrosion Protection: A Combined Experimental and Theoretical Study

“…The experimental findings were corroborated by means of DFT calculations based on effects of cholecalciferol (D3 vitamin) as well as glycerol as its alcoholic solvent in pharmaceutical composition of vitamin D3 solution. The small (TiO 2 ) 10 nanocluster served as a credible model for all possible molecular Ti-implant surface/bioactive molecule interaction predictions [26,27]. There is a possibility that the presence of other kinds of Ti-implant surface/molecule interactions (due to the presence of glycerol solvent) except the (TiO 2 ) 10 -cholecalciferol interaction could be responsible for influencing the coating formation mechanism.…”

“…All calculations were performed by means of quantum chemical calculations at the density functional theory (DFT) level using the Gaussian 09 program (revision D1) [25]. The small (TiO 2 ) 10 nanocluster served as a credible model for all possible molecular surface/bioactive molecule interaction predictions [26,27]. The M06 functional designed by Truhlar's group was selected [28][29][30].…”