Titanium Transfer Lines

Standardization of the Titanium Chloride Solution Drain any standing titanium chloride (TiCl3) from the feed lines and buret, and refill with fresh solution. Add 3.0 g of Ferrous Ammonium Sulfate to a wide-mouth Erlenmeyer flask followed by 200 mL of water, 25 mL of 50% sulfuric acid, 25 mL of 0.1 N Potassium Dichromate Solution (by pipet), and 2 or 3 boiling chips. Boil the solution vigorously on a hot plate for 30 s to remove dissolved air, then quickly transfer the flask to the titration apparatus, securely connect the stopper assembly, and start the carbon dioxide flow and stirrer. Pass carbon dioxide over the solution for 1 min before beginning the titration. 

The reaction between 1 equiv. of the sterically bulky COT" (GOT" = l,4-bis(trimethylsilyl)cyclooctatetraene) ligand and TiCl3(THF)3 did not result in the clean formation of an analogous compound to 160.119 Instead, a mixture of the Ti(n) species (COT")2Ti, the mixed valence Ti(m)/Ti(iv) species (COT")Ti 2(/x-Gl)3 166 and the asymmetric Ti(m) dimeric species (GOT")Ti(/x-Gl) 2(THF) 167 were formed in yields of 15%, 30% and 50%, respectively. X-ray crystallography confirmed that only one of the Ti centers in 167 coordinates to a molecule of THF, although this THF was released when 167 was warmed to 80 °G in vacuo. The EPR spectrum of 167 confirmed that the two Ti centers contained unpaired electrons while that of 166 was consistent with a GOT" Ti(m) species. No unusual line broadening was observed in the EPR spectra of 166 when it was cooled this suggested that the EPR relaxation time was relatively fast compared to any electron transfer between the two titanium centers. 

The mass is cooled and leached in the bucket with 400 ml. of cold water. An iron pestle is used to break up lumps and improve contact. The resulting slurry is filtered rapidly using a Buchner funnel, a fast filter paper, and a paraffin-lined filter flask. The well-compressed filter cake is washed with 100 ml. of water, added in three or four portions. The combined filtrate and wash liquor is transferred to a polyethylene bottle for storage. About 65 to 75% of the titanium from the original mineral is present in the solution. 

Some work has been reported on deposition of hydroxyapatite under hydrothermal conditions, that is much above 100 °C. This includes a study by Liu, Savino and Yates (2011) who coated hydroxyapatite on titanium, stainless steel, aluminium and copper substrates by a seeded hydrothermal deposition method. The deposition strategy included an electrochemical reaction to form quickly a thin layer of HAp seed crystals. Subsequent hydrothermal crystal growth from the seed layer resulted in dense and durable HAp films. In a typical hydrothermal synthesis, a solution of Na2EDTA (0.20 M) and Ca(NOs)2 (0.20 M) was prepared in 15 ml water and a solution of (NH4)2HP04 (0.12 M) in 15 ml water was prepared in a second container. The two source solutions were mixed together after the pH of each solution was raised to 10.0 with ammonium hydroxide. The resulting combined solution was stirred at room temperature for about 20 min and then transferred to a Teflon-lined stainless steel pressure vessel of 40 ml internal volume. 

The first step to the preparation of the mesoporous titania oxide samples is adding dropwise 0.05 moles titanium ethoxide in 60ml aqueous acidie solution (pH = 2). After furAer stirring (lOOrpm) for Ih, the mixture is transferred into a teflon-lined autoclave, and heated at 60°C for 48 hours. The final samples are dried at 60°C in vacuum. 

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