The metastable zone width of ammonium aluminium sulphate and mechanisms of secondary nucleation

1982 ◽  
Vol 47 (4) ◽  
pp. 1184-1188 ◽  
Author(s):  
Jaroslav Nývlt
Keyword(s):  
Seed Crystal ◽  
Fluid Shear ◽  
Secondary Nucleation ◽  
Aluminium Sulphate ◽  
Metastable Zone Width ◽  
Zone Width ◽  
First Case ◽  
Measuring Vessel ◽  
Metastable Zone ◽  
Contact Mechanism

The metastable zone width of aqueous solution of ammonium aluminium sulphate was measured as a function of the cooling rate. The measurements were carried out a) in the absence of seed crystal, b) with one seed crystal at a fixed position in the flowing solution, and c) with one seed crystal moving freely on the bottom of the measuring vessel. The results obtained distinctly differ for the three measurements, providing evidence that primary nucleation took place in the first case, secondary nucleation induced by the surface-layer mechanism combined with fluid shear occurred in the second case, and the contact mechanism of secondary nucleation operated in the third case.

scholarly journals Effect of Impurity Ions on Solubility and Metastable Zone Width of Lithium Metaborate Salts

Crystals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 182
Author(s):  
Dan Li ◽  
Yong Ma ◽  
Lingzong Meng ◽  
Yafei Guo ◽  
Tianlong Deng ◽  
...  
Keyword(s):  
Sodium Chloride ◽  
Regression Method ◽  
Linear Regression Method ◽  
Laser Technique ◽  
Secondary Nucleation ◽  
Metastable Zone Width ◽  
Zone Width ◽  
Lithium Metaborate ◽  
Impurity Ions ◽  
Metastable Zone

The metastable zone width (MZW) of lithium metaborate salts at various concentrations was determined using the laser technique. The solubility data for lithium metaborate salts was nearly the same in the presence of NaCl at various concentrations. The MZW of lithium metaborate salts decreased when the stirring rate increased, but increased remarkably with increasing cooling rates and an increasing concentration of sodium chloride. The apparent secondary nucleation order for lithium metaborate salts was obtained using the Nývlt’s approach. The apparent secondary nucleation order m of lithium metaborate salts is 4.00 in a pure LiBO2−H2O system with an improved linear regression method. The m for lithium metaborate salts was enlarged in the system LiBO2−NaCl−H2O.

scholarly journals The Metastability and Nucleation Thresholds of Ibuprofen in Ethanol and Water-Ethanol Mixtures

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Abdur Rashid ◽  
Edward T. White ◽  
Tony Howes ◽  
James D. Litster ◽  
Ivan Marziano
Keyword(s):  
Water Content ◽  
Propanoic Acid ◽  
Secondary Nucleation ◽  
Metastable Zone Width ◽  
Zone Width ◽  
Primary Nucleation ◽  
Metastable Zone ◽  
The Times ◽  
Induction Times ◽  
Supersaturated Solutions

To investigate the crystallization of ibuprofen [((RS)-2-(4-(2-methylpropyl) phenyl) propanoic acid)] from ethanol and water-ethanol mixtures it is necessary to know the nucleation limits of its solutions. In the absence of crystals, nucleation will seldom occur below the PNT (primary nucleation threshold). If crystals are present, nucleation will seldom occur until below the lower SNT (secondary nucleation threshold). Below the SNT, crystals will still grow with negligible nucleation. PNT and SNT values (expressed as relative supersaturationσ) have been measured at 10, 25, and 40°C for ibuprofen in ethanol and in a range of mixtures of different ethanol (E)/water (W) ratios. The induction times were determined from observing the times to nucleate for a range of different supersaturated solutions at a given temperature andE/Wratio. As expected, lowering the supersaturation leads to longer induction times. In ethanol, the SNT values are small and thus the secondary metastable zone width (MSZW) is relatively narrow with a 1 h SNT relative supersaturation typically aboutσ~ 0.05. The 1 h PNT values are much larger with values forσaround 0.3. In aqueous ethanolic mixtures at 25°C, both the PNT and SNT decrease as the water content increases.

Effect of thermal history of aqueous solutions of KCl on the metastable zone width

1984 ◽  
Vol 49 (3) ◽  
pp. 559-569 ◽  
Author(s):  
Jaroslav Nývlt
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Thermal History ◽  
Equilibrium Solubility ◽  
Metastable Zone Width ◽  
Zone Width ◽  
Preceding Experiment ◽  
History Of ◽  
Metastable Zone ◽  
The Given

The metastable zone width of an aqueous solution of KCI was measured as a function of the time and temperature of overheating above the equilibrium solubility temperature. It has been found that when the experiments follow close upon one another, the parameters of the preceding experiment affect the results of the experiment to follow.The results are interpreted in terms of hypotheses advanced in the literature to account for the effect of thermal history of solution. The plausibility and applicability of these hypotheses are assessed for the given cause of aqueous solution of a well soluble electrolyte.

scholarly journals Solubility and Seeded Metastable Zone width of functional sugar L-arabinose

2015 ◽  
Vol 35 (1) ◽  
pp. 51-57 ◽  
Author(s):  
Biao Hu ◽  
Kai Huang ◽  
Xinlin Zhang ◽  
Pingjun Zhang ◽  
Shujuan Yu
Keyword(s):  
Metastable Zone Width ◽  
Zone Width ◽  
Metastable Zone
Sign in / Sign up

Export Citation Format

Share Document