Mononuclear hydrolysis of titanium (IV) from partition equilibria

Synthesis of Uniform Anatase TiO2 Nanoparticles by Gel–Sol Method

“…The solubility of hydrous TiO 2 is known to be virtually constant above pH 4, but sharply increase below pH 3 (5,8,9,39). The constant solubility above pH 4 may suggest the dominance of the neutral complex, Ti(OH) 4 , and it seems evident that the dominant species in HClO 4 solutions in the pH range, at least, from 1 down to 0 is Ti(OH) 2+ 2 (or TiO 2+ ) from the measurements based on cation-exchange methods (3)(4)(5)(6)(7).…”

“…Relevant textbooks (39), reviews (40,41), and data books (42)(43)(44) are also available. The measurements are based on ion-exchange elution (3), batchwise ion exchange (4-7, 17, 21), ion-exchange chromatography (8,13,25), liquidliquid extraction (9,10,29,32,34,37), potentiometry (14,20,23), dialysis (8,31), solubility measurement (5,8,9,11,29,30,32), spectrophotometry (37,38), radiochemical paper electrophoresis (7), NMR (33), etc. For studying the solution chemistry of hydroxo complexes, the pH control has been performed by using inert acids and bases, such as perchloric acid and sodium hydroxide.…”

The role of surface electrification on the growth and structural features of titania nanoparticles

“…17,18 Above pH 4, the dominance of the neutral soluble species Ti(OH) 4 is reported. 18 During the hydrothermal step dissolution-reprecipitation mechanisms can be expected to take place with Ostwald ripening processes leading to a decrease in the sample surface area (compare S xer ¼ 270 m 2 g À1 for the un-aged precursor with the average of 220 m 2 g À1 of the present samples, see data in Table 1). In the case of the neutral and alkaline pH, the dissolution and re-adsorption of the neutral complexes do not modify the electrification features of the particles.…”

Extração líquido-líquido de ferro(III) e titânio(IV) pelo ácido bis-(2-etil-hexil) fosfórico (D2EHPA) em meio de ácido sulfúrico

“…Soluções de abertura clorídrica aquecidas à ebulição provocam a hidrólise do Ti(IV) precipitando o TiO 2 . [18][19][20] A hidrólise é facilitada pela adição de H 2 SO 4 . 20 Este processo não elimina completamente o Fe do precipitado.…”

“…Além disso, tanto a extração como a reextração do Ti e do Fe são feitas em condições experimentais bem mais brandas que os processos convencionais relatados na literatura. 1,4,8,[18][19][20][21][22] Contudo, as soluções de reextração contêm o íon F -, grave poluente ambiental, exigindo manipulação cuidadosa, mesmo levando-se em contra que a faixa de pH de trabalho (4,5-10) está fora da condição considerada corrosiva (pH < 2 ou > 12,5), e que o processo é conduzido à temperatura ambiente. O reciclo dessas soluções não apenas reduz o consumo de insumos, mas também representa um cuidado ambiental.…”