Naslov
The Influence Of Additives On The Crystallization Of The Hematite From Dense Akaganaite Aqueus Suspensions

Autori
Žic, Mark ; Ristić, Mira ; Musić, Svetozar

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
XXI. Hrvatski skup kemičara i kemijskih inženjera – Knjiga sažetaka / Novak, Predrag ; Pičuljan, Katarina ; Smolec, Sonja - Zagreb : Hrvatsko društvo kemijskih inženjera i tehnologa (HDKI), 2009, 293-293

ISBN
978-953-6894-38-3

Skup
XXI. Hrvatski skup kemičara i kemijskih inženjera

Mjesto i datum
Trogir, Hrvatska, 19.04.2009. - 22.04.2009

Vrsta sudjelovanja
Poster

Vrsta recenzije
Nije recenziran

Ključne riječi
a-Fe2O3; b-FeOOH; morphology; adsorption

Sažetak
Hematite (a-Fe2O3) is widespread mineral in nature (rocks, sediments, soils). It is also important material in many technological applications. Chemical and physical properties of a-Fe2O3 depend on the route of chemical synthesis. In the present work, the hydrothermal crystallization of a-Fe2O3 from dense b-FeOOH suspensions was investigated. a-Fe2O3 particles in the form of double spheres with the ring were formed at 160 oC for 24 h. The orientation effect of a-Fe2O3 subunits in double spheres with the ring was observed. a-Fe2O3 double spheres with the ring also showed two narrow particle size distributions. b-FeOOH transformed to a-Fe2O3 by the dissolution/repreciptation mechanism. The influence of inorganic anions on the phase composition, size and morphology of the particles during the transformation b-FeOOH to a- Fe2O3, was also investigated. With increased concentration of phosphate anion the crystallization of a-Fe2O3 was strongly suppressed. Tendency to the formation of ferrihydrite was noticed. The size and morphology of a-Fe2O3 particles were strongly influenced with added ammonium amidosulphonate (AAS). Up to 24 h of autoclaving the peanut-type a-Fe2O3 particles of good uniformity were obtained. They consisted of laterally arrayed primary a-Fe2O3 particles. Porosity of peanut-type a-Fe2O3 particles was visible. With prolonged autoclaving time up to 72 h and starting concentration 0.1 M AAS, a gradual formation of interconnected (with neck) double cupolas was observed. The cross-section of these cupolas showed that they consisted of linear chains of small interconnected a-Fe2O3 particles directed from the center towards the surface of cupola.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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