Pregled bibliografske jedinice broj: 316180
57Fe MÖSSBAUER, FT-IR AND FE SEM INVESTIGATION OF THE FORMATION OF HEMATITE AND GOETHITE AT HIGH pH VALUES
57Fe MÖSSBAUER, FT-IR AND FE SEM INVESTIGATION OF THE FORMATION OF HEMATITE AND GOETHITE AT HIGH pH VALUES // Croatian-Slovenian Crystallographic Meeting, Book of Abstracts / Cetina, Mario ; Popović Stanko (ur.). (ur.).
Zagreb: Hrvatska akademija znanosti i umjetnosti (HAZU) ; Hrvatska Kristalografska Zajednica, 2007. str. 45-45 (predavanje, međunarodna recenzija, sažetak, znanstveni)
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Naslov
57Fe MÖSSBAUER, FT-IR AND FE SEM INVESTIGATION OF THE FORMATION OF HEMATITE AND GOETHITE AT HIGH pH VALUES
Autori
Žic, Mark ; Ristić, Mira ; Musić, Svetozar
Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni
Izvornik
Croatian-Slovenian Crystallographic Meeting, Book of Abstracts
/ Cetina, Mario ; Popović Stanko (ur.). - Zagreb : Hrvatska akademija znanosti i umjetnosti (HAZU) ; Hrvatska Kristalografska Zajednica, 2007, 45-45
Skup
SIXTEENTH CROATIAN-SLOVENIAN CRYSTALLOGRAPHIC MEETING
Mjesto i datum
Petrčane, Hrvatska, 13.06.2007. - 17.06.2007
Vrsta sudjelovanja
Predavanje
Vrsta recenzije
Međunarodna recenzija
Ključne riječi
alpha-FeOOH; alpha-Fe2O3; FT-IR; Mossbauer
Sažetak
The ferrihydrite suspensions were precipitated at high pH values, and crystallizations of alpha-Fe2O3 and alpha-FeOOH were monitored by Mössbauer and FT-IR spectroscopies and thermal field emission electron microscopy. alpha-Fe2O3 crystallization in dense ferrihydrite suspension at 160 oC was a fast process governed by the dissolution/reprecipitation mechanism. Between 40 and 60 min of crystallization traces/small amounts of alpha-FeOOH precipitated and dissolved, so that between 6 and 24 h only platelet-like alpha-Fe2O3 particles were present. On the other hand, the kinetics of crystallization in a dense ferrihydrite suspension at RT was slow and upon 90 days of ageing alpha-FeOOH an end-product was detected. These alpha-FeOOH particles were strongly elongated along the crystallographic c-axis. alpha-FeOOH particles were also obtained as a single phase at 160 oC, but with decreased Fe3+ concentrations (0.1 or 0.05 M FeCl3). These particles also showed a strong lateral aggregation and the formation of a dendritic microstructure. The crystallization process in a dense ferrihydrite suspension was strongly influenced by ultrasound energy. The application of ultrasound energy of 141 W cm-2 for 2 h induced a coalescence-like effect in the ferrihydrite suspension, as observed by FE SEM. With ultrasound energy increased up to 424 W cm-1 the crystallization of alpha-Fe2O3 particles was observed. The geometrical shape of these alpha-Fe2O3 particles was poor compared with those crystallized in the absence of ultrasound.
Izvorni jezik
Engleski
Znanstvena područja
Kemija
POVEZANOST RADA
Projekti:
098-0982904-2952 - Sinteza i mikrostruktura metalnih oksida i oksidnih stakala (Ristić, Mira, MZOS ) ( CroRIS)
Ustanove:
Institut "Ruđer Bošković", Zagreb
