Heterogeneous Crystallization Research Articles

Heterogeneous Nucleation Regulation Amends Unfavorable Crystallization Orientation and Defect Features of Antimony Selenosulfide Film for High-Efficient Planar Solar Cells.

Antimony selenosulfide (Sb2(S,Se)3) has obtained widespread concern for photovoltaic applications as a light absorber due to superior photoelectric features. Accordingly, various deposition technologies have been developed in recent years, especially hydrothermal deposition method, which has achieved a great success. However, device performances are limited with severe carrier recombination, relating to the quality of absorber and interfaces. Herein, bulk and interface defects are simultaneously suppressed by regulating heterogeneous nucleation kinetics with barium dibromide (BaBr2) introduction. In details, the Br adsorbs and dopes on the polar planes of cadmium sulfide (CdS) buffer layer, promoting the exposure of nonpolar planes of CdS, which facilitates the favorable growth of [hk1]-Sb2(S,Se)3 films possessing superior crystallinity and small interface defects. Additionally, the Se/S ratio is increased due to the replacement of S/Se by Br, causing a downshift of the Fermi levels with a benign band alignment and a shallow-level defect. Moreover, Ba2+ is located at grain boundaries by coordination with S and Se ions, passivating grain boundary defects. Consequently, the efficiency is increased from 7.70% to 10.12%. This work opens an avenue towards regulating the heterogeneous nucleation kinetics of Sb2(S,Se)3 film deposited via hydrothermal deposition approach to optimize its crystalline orientation and defect features.

Templated Nucleation of Clotrimazole and Ketoprofen on Polymer Substrates.

The use of different template surfaces in crystallization experiments can directly influence the nucleation kinetics, crystal growth, and morphology of active pharmaceutical ingredients (APIs). Consequently, templated nucleation is an attractive approach to enhance crystal nucleation kinetics and preferentially nucleate desired crystal polymorphs for solid-form drug molecules, particularly large and flexible molecules that are difficult to crystallize. Herein, we investigate the effect of polymer templates on the crystal nucleation of clotrimazole and ketoprofen with both experiments and computational methods. Crystallization was carried out in toluene solvent for both APIs with a template library consisting of 12 different polymers. In complement to the experimental studies, we developed a computational workflow based on molecular dynamics (MD) and derived descriptors from the simulations to score and rank API-polymer interactions. The descriptors were used to measure the energy of interaction (EOI), hydrogen bonding, and rugosity (surface roughness) similarity between the APIs and polymer templates. We used a variety of machine learning models (14 in total) along with these descriptors to predict the crystallization outcome of the polymer templates. We found that simply rank-ordering the polymers by their API-polymer interaction energy descriptors yielded 92% accuracy in predicting the experimental outcome for clotrimazole and ketoprofen. The most accurate machine learning model for both APIs was found to be a random forest model. Using these models, we were able to predict the crystallization outcomes for all polymers. Additionally, we have performed a feature importance analysis using the trained models and found that the most predictive features are the energy descriptors. These results demonstrate that API-polymer interaction energies are correlated with heterogeneous crystallization outcomes.

Mechanistic investigation of nucleation kinetics in heterogeneous ice crystallization: the role of cooling rate, surface energy, surface nanostructure, and wetting state

The mechanism of nucleation in heterogeneous ice crystallization is important but remains unclear in spite of decades-long research. This study aims at investigating the nucleation kinetics in heterogeneous ice crystallization through molecular dynamics simulations, and comprehensively elucidating the effect of cooling rate, surface energy, surface nanostructure, and wetting state on the nucleation behaviours. More than 300 cases were simulated using monatomic water (mW) model based on a modified Stillinger-Weber (SW) potential. The dynamic nucleation and crystallization behaviours, along with the evolution of the largest ice nucleus, total ice clusters, kinetic energy, and interaction energy between nanodroplet and substrate, were investigated. Increasing the cooling rate and higher surface energy could promote the ice nucleation, but may lead to a tendency to transform into metastable interfacial ice and 4-coordinated molecule types, and create ice-free layer near the substrate due to the strong interaction strength. What's more, the effect of size match between the accessible width and ice lattice constant depends on the wetting states. In Cassie-Baxter state, the size match effect could promote the ice nucleation, while in Wenzel state it is not pronounced and decreasing the contact area by increasing the nanogroove width would inhibit the nucleation process. This work will be valuable in understanding the mechanism of nucleation kinetics in heterogeneous ice crystallization and provide guidance in promoting or inhibiting ice formation.

Efficient and selective CO2 capture at low concentration from CH4 or N2 using Zn-MOF@AFP composite

The synthesis of structured CO2 adsorbents with high separation selectivity, strong stability, and low cost to meet industrial needs is very challenging. Here, we synthesized an ultra-stable Zn-MOF (Zn2(3-amion-1,2,4-triazolate)2(oxalate), Zn2(Atz)2Ox), and adopted an efficient in-situ growth strategy to produce millimeter-sized spherical Zn2(Atz)2Ox@AFP (Amino-Functionalization Poly(acrylates), AFP) composite. Due to the heterogeneous crystallization induced by the nanoscale crystal seeds and the confined space of AFP, the three-dimensional (3D) Zn2(Atz)2Ox bulk crystals transformed into 2D nanosheets with higher CO2 adsorption efficiency and faster kinetics. Zn2(Atz)2Ox@AFP has a high affinity for CO2 (2.05 mmol g−1 at 0.05 bar and 313 K) while exhibiting an inhibitory effect for N2 (only 0.051 mmol g−1 at 1.0 bar and 313 K), leading to an excellent ideal adsorbed solution theory (IAST) selectivity (2990 for CO2/N2 (5/95, v/v)). Interestingly, Zn2(Atz)2Ox@AFP exhibits a unique gating effect on CH4 adsorption, which further extends its application range to natural gas purification. Dynamic breakthrough experiments confirmed that Zn2(Atz)2Ox@AFP can selectively capture CO2 in the simulated CO2/N2 (5/95) and CO2/CH4 (5/95) mixed gases.

Long-Term Inhibiting Salt Crystallization on Photothermal Sheet by a Superhydrophobic CNT Composite Coating

Heterogeneous crystallization resulted in low conversion efficiency and short service life has become one of the important challenges of desalination. Here, a fluoro-modified CNT@epoxy composite coating is developed to durably inhibit salt crystallization of photothermal sheet even in highly concentrated salt water. Typically, it can have stable evaporation efficiency of [Formula: see text] without salt crystallization after continuously being operated for 40 cycles under one solar intensity in the 20[Formula: see text]wt.% NaCl solution. That is mainly due to the Cassie state superhydrophobicity that can large increase the heterogeneous nucleation barrier quite close to the homogeneous one in salt water. This study expects to solve the existing problems of complex structure and short service time of seawater desalination units.

Crystallization of FeC Iron Monocarbide During Peritectoidal Transformation of the Lamellar Eutectoid of Ledeburite White Eutectic Cast Iron

The previously unknown process of homogeneous and heterogeneous crystallization of FeC iron monocarbide and its co-crystallizations with ε-carbide Fe2C from a supersaturated solid solution based on ε-carbide Fe2C or polycarbide quasi-eutectic formed in the process of peritectoid decomposition during prolonged heating (isothermal annealing) of the lamellar eutectoid ledeburite in cast eutectic white iron has been investigated. Crystallization of 2D monolayers of FeC monocarbide allotropes in the form of translucent extended and elastic crystalline nanofilms has been experimentally proved. The carbide phases in white cast iron can be characterized as a single isomorphic and isostructural quasi-carbide solid solution, which structurally crystallizes as a mixture of carbide phases as a quasi-eutectic, in which the carbon content is free to vary widely without indentification of the carbide phases proper. The decomposition product of the lamellar eutectoid as a result of peritectoid transformation during isothermal annealing is polycarbide with a gradient crystal lattice of solid solutions corresponding in carbon concentration to this or that carbide.

Annealing-Induced Heterogeneous Crystallization of Topologically Confined SPEEK Thin Films

Annealing-Induced Heterogeneous Crystallization of Topologically Confined SPEEK Thin Films

Heterogeneous crystallization of Chlorzoxazone for modulating the physicochemical properties of crystals

The polymer on modulating the crystal's habit is an evolving research in pharmaceutical crystallization. This study demonstrates the crystal habit modification of chlorzoxazone (CHZ) by heterogeneous crystallization (HC) in the binary solvent acetonitrile-ethanol (A-E (1:1)) in the presence of polyvinylpyrrolidine (PVP) at concentrations of 0.50, 0.75, and 1.00 wt%. The A-E (1:1) and PVP in HC experiments influenced to change the shape of crystals from needle to plate shape and reduced the crystal size producing a lower aspect ratio (in the range of 1.5–2.3). In the presence of PVP, the CHZ size distribution is 65–78 μm which tends to enhance the powder flow-ability of CHZ crystals and as the PVP concentration increases, the nucleation rate decreases. The solubility of size-reduced CHZ crystals at different pH is found to be improved by 1.2–1.4 times. Hence, HC is deemed effective in modifying the physicochemical attributes of CHZ.

Recovery of copper sulfate from acidic mine waters by membrane crystallization

The recovery of valuable resources from acid mine waters has attracted high interest in moving forward to a circular economy approach. In this work, acidic solutions were processed by a MCr process for the first time, allowing the recovery of copper in the form of copper sulfate crystals. PP and PTFE membranes were investigated at different temperatures (40–80 °C), showing a remarkable water flux decrease over time due to a severe accumulation of crystals on the surface of both PP and PTFE membranes, favoring the heterogeneous crystallization of CuSO4 on the membrane surface instead to the acid solution bulk. The flowrate and acid concentration were also evaluated to find operational conditions that can control crystal accumulation. The high accumulation of crystals was observed for all operating conditions except for a highly acidic condition of 100 g/L acid, where the membrane visually responded by repelling the crystals accumulation on the surface. The membranes were wholly characterized, observing a dramatic impact on the membrane morphology. Results show that copper crystallization by membranes is challenging. Still, considering new membrane materials, operating conditions could allow the process's feasibility.

Scaling behavior in membrane distillation: Effect of Biopolymers and Antiscalants

Fouling and scaling are inherent characteristics of membrane-based separation. They lead to a reduced membrane throughput. In the case of membrane distillation (MD), they can possibly result in pore wetting and irreversible failure to sustain the mass transfer interface. Most prior research on understanding fouling and scaling uses indirect measurements (flux) or ex-situ analyses methods (such as SEM and EDX), which limit the outcomes to indirect qualitative conclusions. Particularly, studying scaling tends to be more challenging due to the complexity of the experiments and the method of investigation; it is imperative to distinguish the contributions from the bulk phase and heterogeneous nucleation. In this work, we established a non-invasive, in-situ, real-time imaging experimental apparatus to study the scaling mechanism. Our experimental setup assisted us in distinguishing distinct phases of scaling during the filtration tests. We studied the scaling mechanism of various single-component systems (sodium chloride, strontium sulfate, calcium sulfate, and calcium carbonate) in vacuum MD filtration. The effect of natural organic matter and antiscalants on gypsum scaling were systematically investigated. Overall, organic fouling on the membrane surface expedited heterogeneous crystallization while decelerating crystal growth in the bulk phase. For instance, deposited humic acid (HA) on the membrane surface promoted gypsum heterogeneous nucleation on the membrane surface due to the interactions between HA carboxylic functional groups and calcium ions. The adsorption of HA on the salt crystal also decelerated crystal growth in the bulk phase. Antiscalants delayed and decelerated both crystal nucleation and crystal growth. PAA, a polycarboxylate antiscalant at 5 ppm, was found to effectively delay the onset of nucleation and crystal growth in the bulk phase, while phosphorous antiscalants at 5 ppm only delayed the onset of nucleation in the bulk phase with a negligible influence on crystal growth. Real-time, in-situ, and non-invasive monitoring shed light on the scaling mechanism and can further be used to identify mitigation strategies.

Analysis of the Influence of Heterogeneous Crystallization Principles on the Formation of Structure and Properties of Foamed Glass

Analysis of the Influence of Heterogeneous Crystallization Principles on the Formation of Structure and Properties of Foamed Glass

Enhanced the simultaneous removal and recovery of phosphorus in induced crystallization coupled biological phosphorus removal process

Remove and recovery of phosphorus from wastewater is expected to be a promising strategy to solve the shortage of phosphorus resources and control the water environment pollution. In this study, induced crystallization coupled biological phosphorus removal (IC-BPR) process was established to achieve simultaneous removal and recovery of phosphorus in wastewater. The effects of side stream ratio (SSR) on the removal and recovery efficiency of phosphorus and the microbial community structure were explored. The results indicated that the SSR of 40% was optimal to phosphorus removal and recovery in the IC-BPR. The total phosphorus removal efficiency was 94.23% under the SSR of 40%, of which the phosphorus removal efficiency by IC accounted for 74.87%. And the total phosphorus recovery efficiency was 67.29%. The particle size and crystal structure analysis of the crystallized products indicated that the increase of SSR was conductive to heterogeneous crystallization. Furthermore, typical polyphosphate accumulation organisms (PAOs), including Rhodocyclaceae, Acinetobacter, and Dechloromonasin, were enriched under the side stream ratio of 40%. And functional genes related to amino acid transport and metabolism, energy production and conversion were activated. The above results indicated that the IC could significantly enhance the removal and recovery of phosphorus under a suitable SSR condition. It will provide important reference for wastewater treatment coupled phosphorus resource recovery technology.

Heterogeneous seed-assisted FAPbI3 crystallization for efficient inverted perovskite solar cells

A heterogeneous seed-assisted FAPbI3 crystallization facilitated by the 2,4-diaminopyrimidine (DAP) molecule, was employed to promotes the highly-crystalline α-FAPbI3 film, significant increasing the efficiency of inverted device to 25.29%.

Competition between homogeneous and heterogeneous crystallization of CaCO3 during water softening

Homogeneous and heterogeneous crystallization of CaCO3 simultaneously occur in seed-induced crystallization during water softening, while suppressing homogeneous crystallization is necessary due to the production of fine particulates that poorly precipitate. However, homogeneous crystallization is difficult to distinguish from heterogeneous crystallization. Consequently, a central focus in improving water softening is understanding their competing activities. In this study, a novel method for distinguishing homogeneous and heterogeneous calcium carbonate crystallization is described that utilizes magnetite as seed particles. Results showed that saturation index (SI) was the primary driver of both homogeneous and heterogeneous crystallizations. Heterogeneous crystallization was preferentially promoted at low SI, while homogeneous crystallization was promoted at high SI. The highest suppression effect to homogeneous crystallization occurred at SI of about 1.01. Seed dosage and mean particle size were the primary parameters related to the competition of the crystallization types. Higher seed dosage and smaller seed particle sizes promoted heterogeneous crystallization and suppressed homogeneous crystallization. Due to the good adaptability of heterogeneous crystallization at low SI, the absorption of CO2 from the air into the solutions also improved the efficiency of hardness removal. The introduction of seed particles did not change crystalline product phases, with calcite being the only observed phase and possessing rhombohedral forms with highly regular and smooth edges. Water softening pilot test results showed that SI of 1.5 was more favorite for CaCO3 layer formation on seed surface and hardness removal in comparison with SI of 1.0 and 2.0. Overall, the results from this study demonstrate that the introduction of seed particles is a promising approach to suppress the homogeneous crystallization of CaCO3. Moreover, these results can serve as a framework for improved seed-induced crystallization during water softening.

Inhibition of jarosite heterogeneous crystallization on anglesite via in-situ formation of competitive substrate

Heterogeneous crystallization is a common occurrence during the formation of solid wastes. It leads to the encapsulation of valuable/hazardous metals within the primary phase, presenting significant challenges for waste treatment and metal recovery. Herein, we proposed a novel method involving the in-situ formation of a competitive substrate during the precipitation of jarosite waste, which is an essential process for removing iron in zinc hydrometallurgy. We observed that the in-situ-formed competitive substrate effectively inhibits the heterogeneous crystallization of jarosite on the surface of anglesite, a lead-rich phase present in the jarosite waste. As a result, the iron content on the anglesite surface decreases from 34.8% to 1.65%. The competitive substrate was identified as schwertmannite, characterized by its loose structure and large surface area. Furthermore, we have elucidated a novel mechanism underlying this inhibition of heterogeneous crystallization, which involves the local supersaturation of jarosite caused by the release of ferric and sulfate ions from the competitive substrate. The local supersaturation promotes the preferential heterogeneous crystallization of jarosite on the competitive substrate. Interestingly, during the formation of jarosite, the competitive substrate gradually vanished through a dissolution-recrystallization process following the Ostwald rule, where a metastable phase slowly transitions to a stable phase. This effectively precluded the introduction of impurities and reduced waste volume. The goal of this study is to provide fresh insights into the mechanism of heterogeneous crystallization control, and to offer practical crystallization strategies conducive to metal separation and recovery from solid waste in industries.

Effect of nucleating agent additions on gahnite based glass-ceramic glazes

The effect of ZrO2 and TiO2 addition in gahnite-based glass-ceramic glazes was investigated by equimolar nucleating agents substituting 5 mol% SiO2. The effect of this substitution on thermal behavior was studied by means of differential thermal analysis and hot stage microscopy. The sintering behavior of samples changed with the type of nucleating agent added. Compacted samples sintered between 850 and 1200 °C for 2 min at 40°Cmin−1 heating and cooling rate for determining the crystallization sequence with using X-ray diffraction. Prepared glaze samples fired at 1180 °C for 6 min in the industrial roller kiln. Total firing time is 58 min from cold to cold. The effect of nucleating agent additions of gahnite-based glass-ceramic glazes was investigated by X-ray diffraction, scanning electron microscopy, spectrophotometer, and gloss meter. Glaze without nucleating agents shows heterogeneous surface crystallization from the frit surface to the inside with dendritic gahnite growth. With the nucleating agent, volume crystallization was seen with phase separation or seeding effect, which depends on the type of nucleating agent. Glaze with TiO2 has two different morphology; one region has fine gahnite crystals below 100 nm, and another region has clusters of nano gahnite crystals in flake-like morphology. ZrO2 provides fine gahnite crystallization, which is smaller than 80 nm. While ZrO2 added glaze is translucent, the other glazes are opaque due to different crystal sizes. It is observed that nano crystallization has a positive effect on pore swelling behavior due to its high crystal surface area. With the addition of the ZrO2 and TiO2, fine-sized nanocrystalline gahnite based glass-ceramic glazes can be obtained for the first time in industrial fast-firing conditions.

Chemical composition-dependent hygroscopic behavior of individual ambient aerosol particles collected at a coastal site

Abstract. This study investigated the hygroscopic behavior of individual ambient aerosol particles collected at a coastal site of Jeju Island, South Korea. The size of the particles changes along with the phase transitions during humidification and dehydration processes, and the chemical compositions of the particles were determined by optical microscopy and scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM-EDX), respectively. Of the 39 particles analyzed, 24 were aged sea spray aerosols (SSAs), with diverse mixing ratios of Cl− and NO3-. The ambient SSAs exhibited multiple deliquescence and efflorescence transitions that were dominantly influenced by NaCl, NaNO3, MgCl2, Mg(NO3)2, and organic species covering the surface of the aged SSAs. For Cl-rich SSAs with X(Na,Mg)Cl>0.4, although some particles showed very slow water uptake at low relative humidity levels (RH ≃30 %), two major transitions were observed during the humidification process. The first was at RH ≃63.8 %, regardless of their chemical compositions, which is the mutual deliquescence relative humidity (MDRH) level; and the second was at RH 67.5 % to 73.5 %, depending on their chemical compositions, which are the final deliquescence relative humidity (DRH) levels. During the dehydration process, the Cl-rich SSAs showed single-stage efflorescence at RH 33.0 % to 50.5 %, due to simultaneous heterogeneous crystallization of inorganic salts. For Cl-depleted SSAs with X(Na,Mg)Cl<0.4, two prompt deliquescence transitions were observed during the humidification process. The first was at MDRH 63.8 %, and the second was at RH 65.4 % to 72.9 %. The mutual deliquescence transition was more distinguishable for Cl-depleted SSAs. During the dehydration process, step-wise transitions were observed at efflorescence RH levels (ERH 24.6 % to 46.0 % and 17.9 % to 30.5 %), depending on their chemical compositions. Additionally, aged mineral particles showed partial or complete phase changes with varying RH due to the presence of SSAs and/or NO3- species. In contrast, non-reacted mineral and Fe-rich particles maintained their size during the entire hygroscopic process. The mixture particles of organic and ammonium sulfate (AS) exhibited lower deliquescence and efflorescence RH levels compared to pure AS salt, highlighting the impact of organic species on the hygroscopic behavior of AS. These findings emphasize the complexity of atmospheric aerosols and the importance of considering their composition and mixing state when modeling their hygroscopic behavior and subsequent atmospheric impacts.

About modification of foundry magnesium alloys

It is shown that the main modifiers of foundry magnesium alloys cannot create heterogeneous crystallization centers in melts during their solidification. Modification of alloy structures is an adsorption‑nanostructural process. It is shown that adsorbed hydrogen is a modifying element of the structures of foundry magnesium alloys. The mechanism of their modification consists in a large decrease in the concentration of adsorbed hydrogen in melts by significantly reducing the concentration of dissolved hydrogen.

A Graphene-Coated Silicon Wafer Plate Improves the Sensitivity and Reproducibility of MALDI-TOF MS Analysis of Proteins.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is widely used to analyze small and large molecules. However, proteins are difficult to analyze with MALDI-TOF MS in clinical applications because of their low ionization efficiency and heterogeneous crystallization with the matrix on the sample spots. Here, we investigate the potential of a customized graphene-coated silicon wafer (G/SiO2) plate for MALDI-TOF MS analysis of a clinically important protein, KPC-2, in comparison with a conventional stainless steel (SUS) plate. Our results demonstrate that the G/SiO2 plate outperforms the SUS plate in terms of sensitivity, reproducibility, and mass accuracy/precision across a wide range of molecular weights, even with highly complex samples. Furthermore, a five-day robustness test confirms the practical applicability of the G/SiO2 plate for the reliable identification of target protein(s) in MALDI-TOF MS analysis. Overall, our findings suggest that the use of the G/SiO2 plate holds great potential for improving the sensitivity and reproducibility of MALDI-TOF MS analysis for the identification of proteins, making it a promising tool for clinical applications.

The Influence of GGBFS as an Additive Replacement on the Kinetics of Cement Hydration and the Mechanical Properties of Cement Mortars

Granulated blast furnace slag (GBFS) is a byproduct of the iron production process. The objective of this study is to determine the effects of ground granulated blast furnace slag (GGBFS), used as a replacement admixture (0–40 wt.%) for ordinary Portland cement (OPC), on the setting time, the heat of hydration, and the mechanical properties of cement mortar. The influence of GGBFS as a replacement additive on the setting time shows that it has an accelerating effect on cement hydration. Calorimetric measurements were performed on the cement paste system to determine the effects of GGBFS on the hydration of OPC. Calorimetric measurements carried out show that the replacement of GGBFS in an amount up to 40 wt.% reduces the total heat of hydration by up to 26.36% compared to the reference specimen. The kinetic analysis performed on the calorimetric data confirms the role of GGBFS as an accelerator by shortening the time during which the process of nucleation and growth (NG), as the most active part of hydration, is reduced up to 2.5 h. The value of the Avrami–Erofee constant indicates polydispersity and heterogeneous crystallization. Mechanical tests of cement mortars were performed after 3, 7, 14, 28, 70, and 90 days of hydration and showed that replacement addition of GGBFS slightly reduced the mechanical properties in the early phase of hydration, while in the later phase of hydration it contributed to an increase in the mechanical properties.