Nucleation Induction Time Research Articles

Impact of Surfactant and Surfactant-Polymer Interaction on Desupersaturation of Clotrimazole

The impact of surfactants on supersaturation of clotrimazole solutions was systematically evaluated. Four clinically relevant surfactants, sodium dodecyl sulfate, vitamin E TPGS, Tween 80, and docusate sodium were studied. The induction time for nucleation and rate of desupersaturation were determined at a supersaturation ratio of 90% amorphous solubility. Measurement was also performed in the presence of predissolved hydroxypropyl methylcellulose acetate succinate to study the effect of surfactant-polymer interaction on desupersaturation. The 4 surfactants showed varied effects on desupersaturation. From supersaturation maintenance perspective, in the presence of hydroxypropyl methylcellulose acetate succinate, the rank order for the 4 surfactants was found to be: docusate sodium > vitamin E TPGS > sodium dodecyl sulfate > Tween 80. Given the importance of maintaining supersaturation and varied effect of surfactants on nucleation kinetics and desupersaturation rate, a careful examination of active pharmaceutical ingredient, polymer and surfactant interaction on an individual basis is recommended for selecting an appropriate surfactant for use in amorphous solid dispersion formulation.

Modeling of hydrate-based CO2 capture with nucleation stage and induction time prediction capability

Gas hydrate technology is a promising approach for carbon capture. However, due to the multi-physics and multi-scale complexity of the process, this technology is not sufficiently understood for real-life scale applications. In particular, further fundamental studies of the hydrate formation mechanisms and rate are needed to achieve relevant insights into the process design and intensification. High-fidelity numerical models are crucial to capture and explain the dominant physicochemical mechanisms involved in the process. This paper presents a new variation of the shrinking core model (SCM) that can capture the practically observed features of the carbon dioxide (CO2) hydration process, including the nucleation phase behavior and induction time, which have not been exploited previously. Accordingly, the most significant contribution of the current work to the literature is the proposal and demonstration of an efficient and rapid predictive tool for the CO2 hydrate nucleation process. Moreover, a model-based estimation of the induction time, as a critical parameter in CO2 hydrate rate estimation and control, is presented. Additionally, the temperature history profile over the nucleation and growth phases is simulated and compared against experimental data from the literature. The proposed model offers an in-depth and rationale analysis tool compared to the primary forms of the SCM and other models in which the nucleation stage has been compromised for the sake of mathematical modeling and numerical solution simplicity. The proposed concept is generic enough to be used for CH4 hydration process too.

Reduction of Fouling and Scaling by Calcium Ions on an UF Membrane Surface for an Enhanced Water Pre-Treatment

The control of fouling and scaling on heat and mass transfer surfaces is of major importance in processes as superficial water treatments, since it also improves the efficiency of the whole process from an energy saving point of view. The aim of the paper is to present the experimental results obtained in the inhibition of the fouling and scaling by calcium ions on an ultrafiltration membrane surface, by using citric acid as an additive. The last is an environmentally friendly additive−a so-called “green additive”, which may represent a reliable alternative to phosphorous and nitrogen based compounds typically used as inhibitors, since it has the characteristics of being non-toxic, non-bio accumulating, and biodegradable. The experimental plant is made of a tangential flow system on a lab scale equipped with a flat sheet ultrafiltration polymeric membrane, whose cut-off is 650 nm. In the first series of experiments, the effect of water hardness and its fouling effect due to calcium ions on membrane permeability has been measured in the range of potable waters. Then, the scaling effect of high calcium concentration in solution (supersaturated conditions) has been quantified by measuring the increase in weight of the membrane, with and without the addition of citric acid as an additive; moreover, the retarding effect of citric acid has been evaluated through the measurement of the induction times for the nucleation of calcium sulfate dihydrate (used as model scalant for fouling). Experiments have been carried out at two different supersaturation ratios (S = 2.25–2.60), at room temperature, in the absence of any additive, and with a citric acid concentration varying in the range 0.01 to 0.50 g/L. Experimental results have shown that the addition of citric acid in solution delays the induction times for gypsum crystals nucleation; moreover, it mitigates the phenomenon of membrane fouling and reduces the pressure drops by allowing an acceptable permeate flow for a longer duration.

Determination of Solubility and Nucleation Kinetics of Valnemulin Hydrochloride Solvate

Dissolution and nucleation are the two indispensable processes to be investigated in order to understand crystallization behavior of a compound. In this study, the crystalline valnemulin hydrochloride water–ethanol solvate (VHWES) was successfully prepared by the solution crystallization method. The solubility of VHWES in ethanol + water binary solvents was measured at eight different temperatures from 278.15 to 313.15 K using a static analytical method, and these solubility data was correlated by several different thermodynamic models. The model parameters were calculated and analyzed based on the difference between calculated results and measured solubility data. It was found that the results correlated by thermodynamic models are in good agreement with the measured solubilities. Furthermore, the nucleation process of VHWES in the ethanol + water (molar ratio of 1:1) system was investigated in detail. The induction times of nucleation and metastable zone width were measured at various temperatures under different supersaturations, and interfacial energies were calculated using classical nucleation theory. The results reveal that homogeneous nucleation predominates under high supersaturation while heterogeneous nucleation predominates under low supersaturation.

Calcium sulphate crystallisation in the presence of mesoporous silica particles: Experiments and population balance modelling

A population balance model is used to investigate the effect of mesoporous silica particles on calcium sulphate crystallisation in a stirred batch crystalliser. The model accounts for nucleation, growth, agglomeration, breakage, and particle-assisted nucleation, and the model equations are solved numerically using the method of classes over a logarithmic, non-uniform mesh. The crystallisation process is characterized experimentally using electrical conductivity to track the ion concentration and laser diffraction to measure the steady-state crystal size distribution obtained at the end of the experiments. The experiments are carried out over a range of temperatures, initial supersaturations, particle pore diameters, and particle loadings. The model is first fitted to experimental data obtained in the absence of particles to determine kinetic parameters of the nucleation, growth, agglomeration, and breakage for pure calcium sulphate crystallisation. Varying pore diameter did not influence the catalytic effect of the particles, however, particle loading was found to significantly decrease the nucleation induction time. The model was extended to account for the presence of particles by fitting two additional mechanisms. The first proposed a particle-assisted nucleation where nuclei are produced via heterogeneous crystallisation, then detach by particle-particle collision that is second-order with respect to particle loading. The second proposed that the crystal breakage frequency increases linearly with particle loading. Good agreement with the experimental data is demonstrated over the range of conditions examined.

Influence of sediment media with different particle sizes on the nucleation of gas hydrate

In order to identify the effect of the particle size of sediment media on the nucleation of gas hydrate (hereinafter referred to as hydrate), we conducted gas hydrate nucleation kinetics experiments on six types of sediment media by using the high-pressure visualized reactor to measure the nucleation induction time of hydrates in sediment media with different particle sizes, based on the size of hydrate-bearing sediments in the Shenhu sea area of the South China Sea. Besides, the nucleation pattern of hydrates in sediment media was analyzed using the probability distribution function. Then, considering the effect of capillarity on the liquid-gas interfacial tension in the pores of sediments, a theoretical model for the pore radius of sediment-nucleation induction time of hydrates was established based on the Kashchiev model in combination with the Arrhenius equation. Finally, the calculation results of the theoretical model were compared with the experimental results. The following results were obtained. First, sediment media with larger particle sizes can help effectively shorten the nucleation induction time of hydrate and increase the concentration degree of induction time. Second, it is deduced from the theoretical model formula that, due to the interfacial tension of pores in the sediment, the nucleation induction time of hydrate increases and then decreases with the increase of sediment particle size, and there is a critical particle size. Third, there is a non-positive correlation between the sediment particle size and the change of hydrate formation difficulty. Within a certain range, the hydrate formation difficulty decreases gradually with the increase of sediment particle size. The research results provide a technical support for the exploration of marine gas hydrate deposits.

Crystallization Inhibition Properties of Cellulose Esters and Ethers for a Group of Chemically Diverse Drugs: Experimental and Computational Insight.

Amorphous solid dispersions are widely used to enhance the oral bioavailability of poorly water-soluble drugs. Polymeric additives are commonly used to delay crystallization of the drug from the supersaturated solutions formed upon ASD dissolution by influencing the nucleation and growth of crystals. However, there is limited evidence regarding the mechanisms by which polymers stabilize supersaturated drug solutions. The current study used experiments and computational modeling to explore polymer-drug interactions in aqueous solutions. Nucleation induction times for supersaturated solutions of nine drugs in the presence of five newly synthesized cellulose-based polymers were evaluated. The polymers had carboxylic acids substituents with additional variations in the side-chain structure: (1) one with a single side chain and a carboxylic acid termination, (2) three with a branched side chain terminated with a carboxylic and an alcohol group (varying the cellulose linkage and the length of the hydrocarbon side chain), and (3) one with a branched side chain with two carboxylic acid end groups. The polymers with a short side chain and one carboxylic acid were effective, whereas the polymers with the two carboxylic acids or a long hydrocarbon chain were less effective. Atomic force microscopy experiments, evaluating polymer adsorption onto amorphous drug films, indicated that the effective polymers were uniformly spread across the surface. These results were supported by molecular dynamics simulations of a polymer chain in the presence of a drug aggregate in an aqueous environment, whereby the effective materials had a higher probability of establishing close contacts and more negative estimated free energies of interaction. The insights provided by this study provide approaches to design highly effective polymers to improve oral drug delivery.

Effect of embedding sodium acetate trihydrate on the Ag anode in an electrical nucleation cell of a supercooled latent heat storage material

Electrical nucleation was investigated by using a Ag anode with sodium acetate trihydrate crystals embedded on the surface in a supercooled aqueous solution of sodium acetate (45–54 wt%) as a latent heat storage device. Rapid electrical nucleation was achieved by applying a direct-current voltage of greater than 1.4 V. When the voltage was set to greater than 1.8 V, the induction time of the electrical nucleation increased as the number of operations increased. The Ag anode life increased when the voltage was less than 1.8 V. When the voltage was 2.0 V, the anode resistance increased as the number of operations increased, with the anode surface deteriorating and forming silver oxide. The repeat life of electrical nucleation at voltages less than 1.8 V was about two times longer than that at voltages greater than 1.8 V. The repeat performance of electrical nucleation and the stability of the supercooled solution were found to depend on the surface roughness, Ra, of the Ag anode. The Ra value was optimized to be in the range 0.6 ≤ Ra ≤ 1.0 µm.

Methane Hydrate Nucleation within Elastic Confined Spaces: Suitable Spacing and Elasticity Can Accelerate the Nucleation.

Elastic materials are candidates for process intensification of gas storage by forming gas hydrate. In this work, molecular dynamics simulations of hydrate nucleation in elastic silica double layers were performed to study the effect of elastic confined spaces on hydrate formation. It is found that in narrow confined spaces, hexagonal rings dominated the hydrogen bond network of water molecules established rapidly by a multisite nucleation mechanism. With molecules added, a bilayer water structure was formed finally because elastic space can adapt the volume expansion. In medium and wide confined spaces, hydrates were formed from a series of "pseudo cages" which are considered as precursors of complete hydrate cages. Moreover, the induction time for nucleation was a minimum when the elasticity of the silica layer changes: nucleation is fastest in the weak-elastic system. When the elasticity increases, it becomes hard to adapt the volume expansion during nucleation and also difficult to nucleate in very weak-elastic systems because of the fluctuation of the layers.

Crystallization from Supersaturated Solutions: Role of Lecithin and Composite Simulated Intestinal Fluid.

The overall purpose of this study was to understand the impact of different biorelevant media types on solubility and crystallization from supersaturated solutions of model compounds (atazanavir, ritonavir, tacrolimus and cilnidipine). The first aim was to understand the influence of the lecithin content in FaSSIF. As the human intestinal fluids (HIFs) contain a variety of bile salts in addition to sodium taurocholate (STC), the second aim was to understand the role of these bile salts (in the presence of lecithin) on solubility and crystallization from supersaturated solutions, METHODS: To study the impact of lecithin, media with 3mM STC concentration but varying lecithin concentration were prepared. To test the impact of different bile salts, a new biorelevant medium (Composite-SIF) with a composition simulating that found in the fasted HIF was prepared. The crystalline and amorphous solubility was determined in these media. Diffusive flux measurements were performed to determine the true supersaturation ratio at the amorphous solubility of the compounds in various media. Nucleation induction times from supersaturated solutions were measured at an initial concentration equal to the amorphous solubility (equivalent supersaturation) of the compound in the given medium. It was observed that, with an increase in lecithin content at constant STC concentration (3mM), the amorphous solubility of atazanavir increased and crystallization was accelerated. However, the crystalline solubility remained fairly constant. Solubility values were higher in FaSSIF compared to Composite-SIF. Longer nucleation induction times were observed for atazanavir, ritonavir and tacrolimus in Composite-SIF compared to FaSSIF at equivalent supersaturation ratios. This study shows that variations in the composition of SIF can lead to differences in the solubility and crystallization tendency of drug molecules, both of which are critical when evaluating supersaturating systems.

Influence of Structurally Related Impurities on the Crystal Nucleation of Curcumin

In this work, the influence of the structurally related impurities, demethoxycurcumin (DMC) and bisdemethoxycurcumin (BDMC) on the primary nucleation of curcumin (CUR) has been investigated in propan-2-ol. The induction time for nucleation was measured at different CUR driving forces and impurity concentrations 0.10 mmol·dm–3, 0.30 mmol·dm–3, and 0.60 mmol·dm–3 and the results are analyzed by the classical nucleation theory (CNT). The nucleation rate for the impure systems was noticeably lower than the nucleation rate of the pure system, and the times of growth to visibility were much longer for the impure systems. The pre-exponential factors are clearly lower for the impure system compared to the pure CUR system, while the increase in the solid–liquid interfacial energy is small. Density functional theory and metadynamic molecular modeling reveal that the 1:1 bonding between CUR and an impurity molecule is stronger than to another CUR molecule, thus suggesting that the developing CUR nucleus has to overc...

The Nucleation Rate of Single O2 Nanobubbles at Pt Nanoelectrodes.

Nanobubble nucleation is a problem that affects efficiency in electrocatalytic reactions since those bubbles can block the surface of the catalytic sites. In this article, we focus on the nucleation rate of O2 nanobubbles resulting from the electrooxidation of H2O2 at Pt disk nanoelectrodes. Bubbles form almost instantaneously when a critical peak current, inbp, is applied, but for lower currents, bubble nucleation is a stochastic process in which the nucleation (induction) time, tind, dramatically decreases as the applied current approaches inbp, a consequence of the local supersaturation level, ζ, increasing at high currents. Here, by applying different currents below inbp, nanobubbles take some time to nucleate and block the surface of the Pt electrode at which the reaction occurs, providing a means to measure the stochastic tind. We study in detail the different conditions in which nanobubbles appear, concluding that the electrode surface needs to be preconditioned to achieve reproducible results. We also measure the activation energy for bubble nucleation, Ea, which varies in the range from (6 to 30)kT, and assuming a spherically cap-shaped nanobubble nucleus, we determine the footprint diameter L = 8–15 nm, the contact angle to the electrode surface θ = 135–155°, and the number of O2 molecules contained in the nucleus (50 to 900 molecules).

An investigation on gas hydrate formation and slurry viscosity in the presence of wax crystals

Clarifying the interaction effect between hydrate and wax is of great significance to guarantee operation safety in deep water petroleum fields. Experiments in a high‐pressure hydrate slurry rheological measurement system were carried out to investigate hydrate formation and slurry viscosity in the presence of wax crystals. Results indicate that the presence of wax crystals can prolong hydrate nucleation induction time, and its influence on hydrate growth depends on multiple factors. Higher stirring rate can obviously promote hydrate growth rate, while its influence on hydrate nucleation induction time is complicated. Higher initial pressure will promote hydrate formation. Gas hydrate slurry shows a shear‐thinning behavior, and slurry viscosity increases with the increase of wax content and initial pressure. A semiempirical viscosity model showing a well‐fitting is established for hydrate slurry with wax crystals by considering the aggregation and breakage of hydrate particles, wax crystals, and water droplets. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3502–3518, 2018

Polymer⁻Surfactant System Based Amorphous Solid Dispersion: Precipitation Inhibition and Bioavailability Enhancement of Itraconazole.

The rapid release of poorly water-soluble drugs from amorphous solid dispersion (ASD) is often associated with the generation of supersaturated solution, which provides a strong driving force for precipitation and results in reduced absorption. Precipitation inhibitors, such as polymers and surfactants, are usually used to stabilize the supersaturated solution by blocking the way of kinetic or thermodynamic crystal growth. To evaluate the combined effect of polymers and surfactants on maintaining the supersaturated state of itraconazole (ITZ), various surfactants were integrated with enteric polymer hydroxypropyl methylcellulose acetate succinate (HPMC AS) to develop polymer–surfactant based solid dispersion. The supersaturation stability was investigated by in vitro supersaturation dissolution test and nucleation induction time measurement. Compared to the ASD prepared with HPMC AS alone, the addition of d-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS) exhibited a synergistic effect on precipitation inhibition. The results indicated that the TPGS not only significantly reduced the degree of supersaturation which is the driving force for precipitation, but also provided steric hindrance to delay crystal growth by absorbing onto the surface of small particles. Subsequently, the formulations were evaluated in vivo in beagle dogs. Compared with commercial product Sporanox®, the formulation prepared with HPMC AS/TPGS exhibited a 1.8-fold increase in the AUC (0–24 h) of ITZ and a 1.43-fold increase of hydroxyitraconazole (OH-ITZ) in the plasma. Similarly, the extent of absorption was increased by more than 40% when compared to the formulation prepared with HPMC AS alone. The results of this study demonstrated that the ASD based on polymer–surfactant system could obviously inhibit drug precipitation in vitro and in vivo, which provides a new access for the development of ASD for poorly water-soluble drug.

Electric-Field-Assisted Protein Crystallization in Continuous Flow

Crystallization is an attractive method for separation and purification of large biomolecules such as proteins due to inherent advantages related to product composition, stability, and process throughput. However, the lack of control over the nucleation and growth of protein crystals complicates design and operation. Electric fields have been used to improve control over the location and induction time of protein nucleation in small batches. To adopt electric-field-assisted protein crystallization as a separation and purification method, a novel device based on continuous flow is presented. The application of continuous flow allows for a large surface-to-volume ratio to be exploited for the electrode design and aligns with the current trend in the (bio)pharmaceutical industry toward continuous manufacturing. The device features millimeter-sized channels with coplanar electrodes to study the influence of nonuniform electric fields on protein crystallization in continuous flow. The results demonstrate that ...

Crystal Nucleation of Tolbutamide in Solution: Relationship to Solvent, Solute Conformation, and Solution Structure.

The influence of the solvent in nucleation of tolbutamide, a medium-sized, flexible and polymorphic organic molecule, has been explored by measuring nucleation induction times, estimating solvent-solute interaction enthalpies using molecular modelling and calorimetric data, probing interactions and clustering with spectroscopy, and modelling solvent-dependence of molecular conformation in solution. The nucleation driving force required to reach the same induction time is strongly solvent-dependent, increasing in the order: acetonitrile<ethyl acetate<n-propanol<toluene. The combined DFT and MD modelling results show that in acetonitrile, ethyl acetate and n-propanol the nucleation difficulty is a function of the strength of solvent-solute interaction, with emphasis on the interaction with specific H-bonding polar sites of importance in the crystal structure. A clear exception from this rule is the most difficult nucleation in toluene despite the weakest solvent-solute interactions. However molecular dynamics modelling predicts that tolbutamide assumes an intramolecularly H-bonded conformation in toluene, substantially different from and more stable than the conformation in the crystal structure, and thus presenting an additional barrier to nucleation. This explains why nucleation in toluene is the most difficult and why the relatively higher propensity for aggregation of tolbutamide molecules in toluene solution, as observed with FTIR spectroscopy, does not translate into easier nucleation. Thus, our combined experimental and molecular modelling study suggests that the solvent can influence on the nucleation not only via differences in the desolvation but also through the influence on molecular conformation.

Inorganic fouling mitigation by salinity cycling in batch reverse osmosis

Enhanced fouling resistance has been observed in recent variants of reverse osmosis (RO) desalination which use time-varying batch or semi-batch processes, such as closed-circuit RO (CCRO) and pulse flow RO (PFRO). However, the mechanisms of batch processes' fouling resistance are not well-understood, and models have not been developed for prediction of their fouling performance. Here, a framework for predicting reverse osmosis fouling is developed by comparing the fluid residence time in batch and continuous (conventional) reverse osmosis systems to the nucleation induction times for crystallization of sparingly soluble salts. This study considers the inorganic foulants calcium sulfate (gypsum), calcium carbonate (calcite), and silica, and the work predicts maximum recovery ratios for the treatment of typical water sources using batch reverse osmosis (BRO) and continuous reverse osmosis. The prediction method is validated through comparisons to the measured time delay for CaSO4 membrane scaling in a bench-scale, recirculating reverse osmosis unit. The maximum recovery ratio for each salt solution (CaCO3, CaSO4) is individually predicted as a function of inlet salinity, as shown in contour plots. Next, the maximum recovery ratios of batch and conventional RO are compared across several water sources, including seawater, brackish groundwater, and RO brine. Batch RO's shorter residence times, associated with cycling from low to high salinity during each batch, enable significantly higher recovery ratios and higher salinity than in continuous RO for all cases examined. Finally, representative brackish RO brine samples were analyzed to determine the maximum possible recovery with batch RO. Overall, the induction time modeling methodology provided here can be used to allow batch RO to operate at high salinity and high recovery, while controlling scaling. The results show that, in addition to its known energy efficiency improvement, batch RO has superior inorganic fouling resistance relative to conventional RO.

Elucidating the impacts of initial supersaturation and seed crystal loading on struvite precipitation kinetics, fines production, and crystal growth

To reduce intra-plant nutrient cycling, and recover phosphorus (P) fertilizers from nutrient-rich sidestreams, wastewater utilities increasingly elect to employ struvite precipitation processes without a clear understanding of the inherent tradeoffs associated with specific design and operating decisions. Specifically, the impact of reactor conditions on struvite crystallization rate, and distribution between formation of fines particles and secondary growth onto large diameter seed crystals represent critical knowledge gaps limiting the predictive capabilities of existing process models. In this work, the relative impacts of initial supersaturation (Si), and seed loading, on P removal kinetics, and struvite solids distribution were investigated. In experiments conducted at different levels of initial supersaturation (1.7–2.4) and seed loading (0–25 g L−1), struvite fines represented the majority of phosphate solids formed in 10 of 12 conditions. While total P removal was dependent on Si, and primarily attributed to formation of fines, the concentration of struvite seed granules had a significant impact on the rate of P removal. Struvite seed granules increased the rate of precipitation by reducing induction time of primary nucleation of struvite fines. Secondary crystal growth represented the majority of struvite solids formed at high seed loading and low Si, but presented the tradeoff of low total removal and low rate of removal. To convey the significance of these findings on process modeling, we show how a prominent kinetic model with a first-order dependency on solid struvite concentration over-predicts P removal rate when total mass is dominated by large diameter seeds (0.9 mm). This works reveals the critical role of struvite fines in P removal, and highlights the need to account for their production and kinetic importance in struvite process design and operation.

Analysis of calcium carbonate polymorphs deposited in water piping system and the effect of tartaric acid additive

Calcium carbonate (CaCO3) formed in a water piping system was investigated in the presence of chemical additives tartaric acid (0.00 and 10.00 ppm) and various temperatures ((27 and 50ºC). The flow rate inside pipe (35 ml/min) were selected. Solutions of CaCl2 and Na2CO3 were prepared in water with equimolar to Ca2+ concentration of 3000 ppm. The induction time of scale nucleation varied from 24 min to 44 min. An increasing temperature of the solution resulted in more CaCO3 scale, mass, while the higher tartaric acid made the reduced mass of scales by 90%. SEM/EDS analysis verified CaCO3 with a plate like morphology. Also the XRPD Rietveld method provided the confirmation of a major phase of calcite and vaterite minerals followed by the minor of aragonite in the absence of tartaric acid and at room temperature. However, the presence of 10 ppm tartaric acid yielded the increasing result of calcite, while aragonite precipitation was hampered under the influence of tartaric acid. The presence of tartaric acid at increasing temperature of 50ºC could delay formation of calcite, whereas aragonite could be formed significantly. Thus the study showed the capacity of the tartaric acid in influencing CaCO3 crystallization.

Towards establishing a combined rate law of nucleation and crystal growth – The case study of gypsum precipitation

The main obstacle in the formulation of a quantitative rate-model for mineral precipitation is the absence of a rigorous method for coupling nucleation and growth processes. In order to link both processes, we conducted a series of batch experiments in which gypsum nucleation was followed by crystal growth. Experiments were carried out using various stirring methods in several batch vessels made of different materials. In the experiments, the initial degree of supersaturation of the solution with respect to gypsum (Ωgyp) was set between 1.58 and 1.82. Under these conditions, heterogeneous nucleation is the dominant nucleation mode. Based on changes in SO42− concentration with time, the induction time of gypsum nucleation and the following rate of crystal growth were calculated for each experiment. The induction time (6–104 h) was found to be a function of the vessel material, while the rates of crystal growth, which varied over three orders of magnitude, were strongly affected by the stirring speed and its mode (i.e. rocking, shaking, magnetic stirrer, and magnetic impeller). The SO42− concentration data were then used to formulate a forward model that couples the simple rate laws for nucleation and crystal growth of gypsum into a single kinetic model. Accordingly, the obtained rate law is based on classical nucleation theory and heterogeneous crystal growth.