High-Aspect-Ratio Titanium Oxide Nanotubes Anodized in KH2PO4/NH4F/Citric Acid Electrolytes

Titanium of 99.7% purity was anodized in 1M potassium phosphate monobasic (KH2PO4) water solution with 0.15M NH4F. Titanium oxide nanotubes were fabricated at anodization potential of 20 V and 4.64 pH. To control the pH of the solution, we have added weak acid such as citric acid because it has three dissociation constants (pKa) of 3.09, 4.75, and 5.41. Citric acid was very useful to control the pH of the 1M KH2PO4 water electrolyte solution within 3 to 5. The diameter and length of the titanium oxide nanotubes were independent on anodization time. The diameter of 120 nm and length of 2.8 μm at anodization time of 5 hrs were observed by field emission scanning electron microscope (FESEM). Undesired thin oxide layer blocking the top of titanium oxide nanotubes was wiped out by increasing the anodization potential with the multi step voltage by 1 V reached to 25 V. The titanium oxide nanotubes having a very large surface area are very attractive for the battery, gas sensor, photocatalytic application, and biomaterials.

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Titanium Oxide Nanotubes: Synthesis of Anatase Phase, Characterization and Photocatalytic Application

Revista Virtual de Química ◽

10.5935/1984-6835.20130045 ◽

2013 ◽

Vol 5 (4) ◽

Cited By ~ 2

Author(s):

J. T. Filho ◽

A. M. Rocco

Keyword(s):

Titanium Oxide ◽

Anatase Phase ◽

Titanium Oxide Nanotubes ◽

Photocatalytic Application ◽

Phase Characterization

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Titanium oxide nanotube arrays prepared by anodic oxidation

Journal of Materials Research ◽

10.1557/jmr.2001.0457 ◽

2001 ◽

Vol 16 (12) ◽

pp. 3331-3334 ◽

Cited By ~ 1548

Author(s):

Dawei Gong ◽

Craig A. Grimes ◽

Oomman K. Varghese ◽

Wenchong Hu ◽

R. S. Singh ◽

...

Keyword(s):

Titanium Oxide ◽

Anodic Oxidation ◽

Hydrofluoric Acid ◽

Layer Structure ◽

Porous Alumina ◽

Pure Titanium ◽

Nanotube Arrays ◽

Titanium Sheet ◽

Anodization Time ◽

Titanium Oxide Nanotubes

Titanium oxide nanotubes were fabricated by anodic oxidation of a pure titanium sheet in an aqueous solution containing 0.5 to 3.5 wt% hydrofluoric acid. These tubes are well aligned and organized into high-density uniform arrays. While the tops of the tubes are open, the bottoms of the tubes are closed, forming a barrier layer structure similar to that of porous alumina. The average tube diameter, ranging in size from 25 to 65 nm, was found to increase with increasing anodizing voltage, while the length of the tube was found independent of anodization time. A possible growth mechanism is presented.

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Overcoming Hard Water Antagonistic to Glyphosate or Imazethapyr with Water Conditioners

Notulae Scientia Biologicae ◽

10.15835/nsb629300 ◽

2014 ◽

Vol 6 (2) ◽

pp. 244-249

Author(s):

Akbar ALIVERDI ◽

Ali GANBARI ◽

Mohammad-Hassan RASHED MOHASSEL ◽

Mehdi NASSIRI-MAHALLATI ◽

Eskandar ZAND

Keyword(s):

Magnetic Field ◽

Citric Acid ◽

Ammonium Nitrate ◽

Ammonium Sulfate ◽

Potassium Phosphate ◽

Hard Water ◽

Weak Acid ◽

Distilled Water ◽

Water Conditioning ◽

Acid Herbicides

Carrier water quality may affect the activity of weak acid herbicides when concentrations of some cations are high. A dose-response experiment on glyphosate and imazethapyr activity, which were carried by the carrier types of distilled water and hard water, against jimsonweed were conducted to compare the water conditioning chemicals ammonium sulfate, ammonium nitrate, citric acid and potassium phosphate, with magnetized carrier as a new method. A magnetic field of 0.7 Tesla was applied to prepare the magnetized carrier. With the exception of potassium phosphate with imazethapyr, the activity of glyphosate and imazethapyr was significantly increased in the presence of the water conditioning methods when distilled water was used as the carrier. Ammonium sulfate was the most effective method. The activity of both herbicides was decreased when applied with hard water carrier. Potassium phosphate was not effective at reducing the antagonism of cations in the hard water carrier. In glyphosate, the performance of water conditioning methods in softening hard water carrier could be ranked as follows: ammonium sulfate (2.52-fold) > magnetized carrier (2.12-fold) ≥ citric acid (1.64-fold) ≥ ammonium nitrate (1.39-fold) > potassium phosphate (0.96-fold). In imazethapyr, this order was as follows: ammonium sulfate (2.99-fold) > ammonium nitrate (2.66-fold) > magnetized carrier (1.81-fold) ≥ citric acid (1.64-fold) > potassium phosphate (1.10-fold).

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