Effect of Solution-pH on Methylene Blue Dye Adsorption on Hydrogen Titanate Nanotubes Processed via Hydrothermal Method

Facile synthesis of γ-Fe2O3 nanoparticles integrated H2Ti3O7 nanotubes structure as a magnetically recyclable dye-removal catalyst

“…32 The values of different parameters estimated aer tting the three equilibrium isotherm models, Fig. 32 In the present investigation, the equilibrium adsorption of MB on the surface of pure HTN and HTNF magnetic nanocomposites follows both the Langmuir and DKR models at the initial solution-pH of $10 which is in agreement with the reported trend. Evidently, the q m values obtained via the Langmuir and DKR models are observed to be in agreement with the experimentally observed values.…”

“…The decrease in q e at higher initial MB concentration has been attributed to the strong interaction of cationic MB molecules with the OH À ions within the solution which restricts the adsorption of latter on the surface of adsorbent, thus reducing the negative surface-charge developed on the surface of adsorbent under these test-conditions. 32 The MB adsorption capacity (q m ) is estimated to be 113, 99, 75, and 66 mg g À1 for the HTN, HTNF-5, HTNF-10, and HTNF-25 samples respectively. Within the investigated range of initial MB concentration, the MB dye-adsorption capacity of g-Fe 2 O 3 nanoparticles at the initial solution-pH of $10 is determined to be very small ($13 mg g À1 ) (also see Fig.…”

“…32 The values of different parameters estimated aer tting the three equilibrium isotherm models, Fig. 32 The values of different parameters estimated aer tting the three equilibrium isotherm models, Fig.…”

Hydrothermal synthesis of highly crystalline nanotubes/nanoplates of pure and silver-doped anatase-titania using acid-catalyst-modified sol–gel precursors

“…It is, thus, unambiguously confirmed that when the nanocrystalline anatase-TiO 2 processed via the CH 3 COOH-modified solgel method is used as a precursor during the hydrothermal processing, the final hydrothermal products (nanotubes/ nanoplates) also have the highly crystalline anatasestructure irrespective of the amount of Ag-doping. Since several investigations have already reported the formation of nanotubes of hydrogen titanate when the anatase-TiO 2 is used as a precursor [31][32][33][34]47], the formation of nanotubes/nanoplates of anatase-TiO 2 is striking and attributed here to the effect of precursor-modification due to its processing via the CH 3 COOH-modified sol-gel method.…”

“…However, there are no reports in the literature which demonstrate the processing of pure and doped highly crystalline anatase-TiO 2 nanotubes/nanoplates via the hydrothermal method using the acid-catalyst modified sol-gel precursors which can eliminate the thermal treatment. In our previous investigations [31][32][33][34], the pure nanocrystalline anatase-TiO 2 was used as a precursor which invariably transforms to the nanotubes of hydrogen titanate when subjected to the hydrothermal and subsequent washing-treatments. In view of this, the first major objective of the present investigation is to introduce a systematic procedure for demonstrating the effect of prior precursor-modification using an acid-catalyst on the development of highly crystalline pure and Ag-doped nanotubes/nanoplates of anatase-TiO 2 (instead of those of hydrogen titanante) via the hydrothermal method without the involvement of thermal treatment; while, the second major objective of the present investigation is to propose a possible mechanism for obtaining this new phase under the given processing conditions (that is, with the use of an acid-catalyst-modified sol-gel precursor and without the involvement of thermal treatment).…”