Studies on nucleation and crystal growth kinetics of plutonium(IV) oxalatex

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Chuanbo Li ◽  
Bo Wang ◽  
Xiang Li ◽  
Taihong Yan ◽  
Weifang Zheng
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
Nucleation Rate ◽  
Crystal Growth Rate ◽  
Acid Solutions ◽  
Dilution Ratio ◽  
Secondary Nucleation ◽  
Supersaturation Ratio ◽  
Crystal Growth Kinetics ◽  
Kinetics Of

Abstract A new method is developed to calculate the dilution ratio N of the two reactant solutions during nucleation rate determination. When the initial apparent supersaturation ratio S N  = f(N) in the dilution tank is controlled between 1.66 and 1.67, the counted nuclei is the most, both nuclei dissolving and secondary nucleation avoided satisfactorily. Based on this methoed, Plutonium(IV) oxalate is precipitated by mixing equal volumes of tetravalent plutonium nitrate and oxalic acid solutions. Experiments are carried out by varying the supersaturation ratio from 8.37 to 22.47 and temperature from 25 to 50 °C. The experimental results show that the nucleation rate of plutonium(IV) oxalate in the supersaturation range cited above can be expressed by the equation R N  = A N exp(−E a /RT)exp[−B/(ln S)2], where A N  = 4.8 × 1023 m−3 s−1 , and E a  = 36.2 kJ mol−1, and B = 20.2. The crystal growth rate of plutonium(IV) oxalate is determined by adding seed crystals into a batch crystallizer. The crystal growth rate can be expressed by equation G(t) = k g exp(−E’ a /RT) (c − c eq) g , where k g  = 7.3 × 10−7 (mol/L)−1.1(m/s), E’ a  = 25.7 kJ mol−1, and g = 1.1.

Studies on nucleation and crystal growth kinetics of uranium(IV) oxalate

2020 ◽  
Vol 108 (3) ◽  
pp. 185-193
Author(s):  
Chuanbo Li ◽  
Yongzhi Ning ◽  
Taihong Yan ◽  
Weifang Zheng
Keyword(s):  
Crystal Growth ◽  
Nucleation Rate ◽  
Oxalic Acid Solution ◽  
Supersaturation Ratio ◽  
Tetravalent Uranium ◽  
Reaction Solution ◽  
Crystal Growth Kinetics ◽  
Uranium Nitrate ◽  
Kinetics Of ◽  
Homogeneous Mechanism

AbstractAn improved apparatus is used for nucleation measurements according to Nielsen’s method. A new method is proposed to calculate the dilution ratio N of the reaction solution during nucleation rate determination. With the rule, when the initial apparent supersaturation ratio S′ = f(N) in the dilution tank is controlled from 1.2 to 2.7, crystal nucleus dissolving and secondary nucleation can be avoided satisfactorily. Experiments are realized by varying the supersaturation ratio from 26.0 to 297.5 and temperature from 30 °C to 50 °C. Uranium(IV) oxalate is precipitated by mixing equal volumes of tetravalent uranium nitrate and oxalic acid solution. The experimental results show that the nucleation rate of uranium(IV) oxalate in the supersaturation range as show above is characterized by the primary homogeneous mechanism and can be expressed by the equation ${R_N} = {A_N}{\rm{exp}}( - {E_a}/RT){\rm{exp}}[ - B/{({\rm{ln }}S)^2}],$ where AN = 1.9 × 1027 m−3s−1, Ea = 71.2 kJ mol−1, and B = 34.3. The crystal growth rate can be expressed by the equation $G(t) = {k_g}{\rm{exp(}} - {E^{\prime}_a}/RT{\rm{)(}}c - {c_{{\rm{eq}}}}{{\rm{)}}^g},$ where kg = 7.1 × 105 (mol/L)−0.98 (m/s), ${E^{\prime}_a} = 33.1 \ {\rm{ kJ \ mo}}{{\rm{l}}^{ - 1}},$ and g = 0.98. The results indicate that the crystal growth of tetravalent uranium(IV) oxalate is controlled by the BCF model.

Crystal-growth kinetics of protein single crystals along capillary tubes in the gel-acupuncture technique

1999 ◽  
Vol 55 (2) ◽  
pp. 577-580 ◽  
Author(s):  
Abel Moreno ◽  
Manuel Soriano-García
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
Capillary Tube ◽  
Crystal Growth Rate ◽  
Equilibrium Studies ◽  
Acta Cryst ◽  
Average Growth ◽  
X Ray Crystallography ◽  
Growing Cell ◽  
Kinetics Of

In attempts to obtain protein crystals of a sufficient size for structural studies, lack of knowledge of the physicochemical properties of protein solutions and of their crystal-growth behaviour lead to a bottleneck for drug design as well as for X-ray crystallography. Most formal investigations on crystal-growth phenomena have been focused on equilibrium studies, where the protein is soluble, and on the kinetics of crystal growth, which is related to both nucleation and crystal-growth phenomena. The aim of this work is to measure the crystal-growth rate along a capillary tube used as a growing cell. These experiments were carried out using the gel-acupuncture technique [García-Ruiz et al. (1993). Mater. Res. Bull. 28, 541–546; García-Ruiz & Moreno (1994). Acta Cryst. D50, 484–490; García-Ruiz & Moreno (1997). J. Cryst. Growth, 178, 393–401]. Crystal-growth investigations took place using lysozyme and thaumatin I as standard proteins. The maximum average growth rate obtained in the lower part of the capillary tube was about 35 Å s−1 and the minimum average growing rate in the upper part of the capillary tube was about 8 Å s−1. The crystal-growth rate as a function of the supersaturation was experimentally estimated at a constant height along the capillary tube.

Crystallization kinetics for the system CuSO4-ZnSO4-H2O forming solid solutions

1986 ◽  
Vol 51 (11) ◽  
pp. 2473-2480 ◽  
Author(s):  
Jaroslav Nývlt ◽  
Věra Šnoblová ◽  
Miloslav Karel
Keyword(s):  
Solid Solution ◽  
Growth Rate ◽  
Crystal Growth ◽  
Fluidized Bed ◽  
Solid Solutions ◽  
Nucleation Rate ◽  
Diffusion Mechanism ◽  
Crystal Growth Rate ◽  
Component System ◽  
Metastable Zone

The three-component system CuSO4-ZnSO4-H2O forms three types of solid solution. Metastable zone widths measured for selected solution compositions at two cooling rates were used to calculate the kinetic parameters of nucleation. The rate of crystal growth was measured by the fluidized bed method. The results show that the addition of Zn2+ to a solution of CuSO4 increases both the nucleation and crystal growth rates, whereas Cu2+ added to a solution of ZnSO4 retards the nucleation rate and slightly increases the rate of crystal growth. The nucleation rate (the metastable zone width) is substantially more sensitive to the addition of a second component than is the rate of crystal growth. The crystal growth rate is controlled by a diffusion mechanism.

scholarly journals Co-Crystallization Kinetics of 2:1 Benzoic Acid–Sodium Benzoate Co-Crystal: The Effect of Templating Molecules in a Solution

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 812
Author(s):  
Freshsya Zata Lini ◽  
Dhanang Edy Pratama ◽  
Tu Lee
Keyword(s):  
Growth Rate ◽  
Free Energy ◽  
Crystal Growth ◽  
Energy Barrier ◽  
Crystal Growth Rate ◽  
Supramolecular Assemblies ◽  
Solution Phase ◽  
Crystal Habit ◽  
Free Energy Barrier ◽  
Kinetics Of

The addition of dissolved templating molecules in crystallization will create “supramolecular assemblies” within the solution, serving as “anchor points” for the solute molecules to nucleate and grow. In this work, nucleation and crystal growth kinetics of 2:1 benzoic acid (HBz)–sodium benzoate (NaBz) co-crystallization with or without templates in a solution were analyzed by monitoring the concentration of the mother liquor during cooling crystallization. The results showed that the addition of the dissolved 2:1 or 1:1 HBz–NaBz co-crystals as templating molecules could reduce the critical free energy barrier of 2:1 HBz–NaBz co-crystal during its nucleation, but did not significantly affect the order of crystal growth rate. On the other hand, the critical free energy barrier of the nucleation process was increased if dissolved NaBz was used as a templating molecule, while a significant rise in the order of crystal growth rate occurred. The crystal habit obtained from the NaBz-templated system was needle-like, suggesting that sodium–sodium coordination chains of NaBz supramolecular assemblies in the solution phase were responsible for creating elongated crystals. Conversely, a large prismatic crystal habit found in non-templated and 2:1 and 1:1 HBz–NaBz co-crystal-templated systems implied that those templating molecules formed sparsely interconnected supramolecular assemblies in the solution phase.

scholarly journals Reactive Crystallization Kinetics of K2SO4 from Picromerite-Based MgSO4 and KCl

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1558
Author(s):  
Abad Albis ◽  
Yecid P. Jiménez ◽  
Teófilo A. Graber ◽  
Heike Lorenz
Keyword(s):  
Crystal Growth ◽  
Nucleation Rate ◽  
Length Distribution ◽  
Analytical Techniques ◽  
Nucleation And Growth ◽  
Solution Temperature ◽  
Secondary Nucleation ◽  
Primary Nucleation ◽  
Reactive Crystallization ◽  
Kinetics Of

In this work, the kinetic parameters, the degrees of initial supersaturation (S0) and the profiles of supersaturation (S) were determined for the reactive crystallization of K2SO4 from picromerite (K2SO4.MgSO4.6H2O) and KCl. Different reaction temperatures between 5 and 45 °C were considered, and several process analytical techniques were applied. Along with the solution temperature, the crystal chord length distribution (CLD) was continuously followed by an FBRM probe, images of nucleation and growth events as well as the crystal morphology were captured, and the absorbance of the solution was measured via ATR-FTIR spectroscopy. In addition, the ion concentrations were analyzed. It was found that S0 is inversely proportional to the reactive crystallization temperature in the K+, Mg2+/Cl−, SO42−//H2O system at 25 °C, where S0 promotes nucleation and crystal growth of K2SO4 leading to a bimodal CLD. The CLD was converted to square-weighted chord lengths for each S0 to determine the secondary nucleation rate (B), crystal growth rate (G), and suspension density (MT). By correlation, from primary nucleation rate (Bb) and G with S0, the empirical parameters b = 3.61 and g = 4.61 were obtained as the order of primary nucleation and growth, respectively. B versus G and MT were correlated to the reaction temperature providing the rate constants of B and respective activation energy, E = 69.83 kJ∙mol−1. Finally, a general Equation was derived that describes B with parameters KR = 13,810.8, i = 0.75 and j = 0.71. The K2SO4 crystals produced were of high purity, containing maximal 0.51 wt% Mg impurity, and were received with ~73% yield at 5 °C.

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