scholarly journals Minimum seed crystal size for secondary nucleation of potassium alum in a stirred-vessel crystallizer.

1990 ◽  
Vol 23 (6) ◽  
pp. 691-696 ◽  
Author(s):  
Noriaki Kubota ◽  
Masato Fujiwara
Keyword(s):  
Crystal Size ◽  
Seed Crystal ◽  
Secondary Nucleation ◽  
Potassium Alum ◽  
Stirred Vessel

Continuous Precipitation of Lead Iodide

1994 ◽  
Vol 59 (7) ◽  
pp. 1503-1510
Author(s):  
Stanislav Žáček ◽  
Jaroslav Nývlt
Keyword(s):  
Growth Rate ◽  
Particle Size ◽  
Crystal Size ◽  
Crystal Growth Rate ◽  
Laboratory Model ◽  
Lead Iodide ◽  
Secondary Nucleation ◽  
Equimolar Ratio ◽  
Continuous Precipitation ◽  
The Mean

Lead iodide was precipitated from aqueous solutions of 0.015 - 0.1 M Pb(NO3)2 and 0.03 - 0.2 M KI in the equimolar ratio using a laboratory model of a stirred continuous crystallizer at 22 °C. After reaching the steady state, the PbI2 crystal size distribution was measured sedimentometrically and the crystallization kinetics was evaluated based on the mean particle size. Both the linear crystal growth rate and the nucleation rate depend on the specific output of the crystallizer. The system crystallization constant either points to a significant effect of secondary nucleation by the mechanism of contact of the crystals with the stirrer blade, or depends on the concentrations of the components added due to the micromixing mechanism.

Batch Crystallization with Crystals Attrition

1993 ◽  
Vol 58 (8) ◽  
pp. 1855-1860 ◽  
Author(s):  
Jaroslav Nývlt ◽  
Stanislav Žáček
Keyword(s):  
Mathematical Model ◽  
Calcium Sulfate ◽  
Crystal Size ◽  
Theoretical Description ◽  
Secondary Nucleation ◽  
Batch Crystallization ◽  
Batch Time ◽  
The Mean

The dependence of the mean crystal size of the products from batch crystallizers on the batch time occasionally exhibits a maximum, which can be explained by secondary nucleation due to the attrition of crystals. A kinetic equatation of nucleation, comprising a term for crystal attrition, can be used for the theoretical description of such behaviour. A mathematical model of a batch crystallizer with crystal attrition has been verified on the calcium sulfate precipitation.

scholarly journals Continuously monitored lactose crystallization in a vibrated bed

2019 ◽  
Vol 22 ◽  
Author(s):  
Gustavo Araújo Teixeira ◽  
Fabio Ferreira Batista ◽  
Ricardo Amâncio Malagoni ◽  
José Roberto Delalibera Finzer
Keyword(s):  
Stainless Steel ◽  
Vibration Frequency ◽  
Crystal Size ◽  
Cheese Whey ◽  
Dense Phase ◽  
Secondary Nucleation ◽  
Vibratory System ◽  
Reflectance Measurement ◽  
Vision Measurement ◽  
Focused Beam

Abstract The aim of this work was to evaluate the crystal size distribution (CSD) and microscopy of the crystalline phase in isothermal lactose crystallization, using a high seeding concentration (dense phase). In-line monitoring was carried out using Focused Beam Reflectance Measurement (FBRM) and Particle Vision Measurement (PVM) probes in a stainless steel trunk-conical shaped jacketed crystallizer. The vibratory shaking system consisted of two perforated discs coupled to a movable axle. A conventional crystallization unit, with a three-blade propeller attached to a stainless steel shaft, was used for comparison. Concentrated cheese whey, purified with an organic coagulant, and commercial lactose solutions were used. Crystallization was improved in the high-purity solutions. Microparticles and/or aggregates appeared before seeding, mainly in the purified cheese whey solution, in which there are impurities. Secondary nucleation was present in both the vibratory agitation and conventional rotary agitation systems, being intensified by increases in agitation. Crystallization in a vibratory system should be carried out with a vibration frequency of 250 rpm, since an increase to 400 rpm reduced the amount of larger crystals.

scholarly journals A perspective on the growth-only zone, the secondary nucleation threshold and crystal size distribution in solution crystallisation

CrystEngComm ◽  
2016 ◽  
Vol 18 (3) ◽  
pp. 369-378 ◽  
Author(s):  
Terence L. Threlfall ◽  
Simon J. Coles
Keyword(s):  
Size Distribution ◽  
Crystal Size ◽  
Crystal Size Distribution ◽  
Solubility Curve ◽  
Secondary Nucleation ◽  
Metastable Zone

The metastable zone between the solubility curve and the crystallisation curve can be divided into two regions, separated by the secondary nucleation threshold.

scholarly journals SECONDARY NUCLEATION OF K-ALUM BY MIN-IMUM SIZE SEEDS IN A STIRRED VESSEL

1977 ◽  
Vol 10 (1) ◽  
pp. 35-39 ◽  
Author(s):  
KEN TOYOKURA ◽  
JUNICHI MOGI ◽  
IZUMI HIRASAWA
Keyword(s):  
Secondary Nucleation ◽  
Stirred Vessel

Effect of Seed Crystal Size on the Properties of Silicalite-1 Membranes Synthesized in a Fluoride Containing Medium

2017 ◽  
Vol 50 (5) ◽  
pp. 345-350 ◽  
Author(s):  
Lingfang Qiu ◽  
Izumi Kumakiri ◽  
Kazuhiro Tanaka ◽  
Xiangshu Chen ◽  
Hidetoshi Kita
Keyword(s):  
Crystal Size ◽  
Seed Crystal

scholarly journals Al-ZSM-5 Nanocrystal Catalysts Grown from Silicalite-1 Seeds for Methane Conversion

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 485
Author(s):  
Hyun Su Kim ◽  
Su Kyung Kang ◽  
Haoxiang Zhang ◽  
Elsa Tsegay Tikue ◽  
Jin Hyung Lee ◽  
...  
Keyword(s):  
Rapid Growth ◽  
Methane Conversion ◽  
Crystal Size ◽  
Reaction System ◽  
Seed Crystal ◽  
Catalyst Stability ◽  
Synthesis Time ◽  
Seed Crystals ◽  
Synthesis Conditions ◽  
Methane Dehydroaromatization

This study evaluated Al-ZSM-5 nanocrystals grown from silicalite-1 seed crystals as catalysts for the methane dehydroaromatization (MDA) reaction. Silicalite-1 seed crystals sized between 30 and 40 nm were used to grow Al-ZSM-5 under various synthesis conditions. The size of Al-ZSM-5 was significantly affected by the Si/Al ratio (SAR), synthesis time, and silica nutrients/seed crystal ratio (NSR). Larger crystals were obtained with an increased SAR in the synthesis sols. Gradual growth of Al-ZSM-5 occurred with synthesis time, although the growth in crystal size ceased at 5 h of synthesis at 120 °C, indicating the rapid growth of Al-ZSM-5 aided by the silicalite-1 seeds. Precise tuning of Al-ZSM-5 size was possible by changing the nutrient/silicalite-1 seed ratio; a higher NSR led to larger crystals. Two representative Al-ZSM-5 crystals with SARs of 35 and 140 were prepared for catalyst testing, and the crystal sizes were tailored to <100 nm by controlling NSR. The MDA reaction was conducted in the presence of the prepared Al-ZSM-5. The catalyst size exhibited distinct differences in catalyst stability, while the SAR of catalysts did not produce noticeable changes in the catalyst stability of the Al-ZSM-5 crystals and commercial zeolites in this reaction system.

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