Name: crystal formation through supersaturation
Uploaded: 2025-05-22T09:05:36.000Z
Duration: 1 min 25 s
Channel: JoVE

Crystallization is a phase transformation process where crystals are formed from a source like a cooling saturated solution.
Crystallization begins with primary nucleation, which starts from a clear solution without any pre-existing crystals to aid the process. It is divided into homogeneous and heterogeneous types.
During heterogeneous nucleation, the crystals form on nucleating surfaces like dust particles. In contrast, homogeneous nucleation takes place in a clear solution without any heterogeneous particulates.
During secondary nucleation, the growth occurs due to parent crystals like those introduced through seeding.
Nucleating clusters that reach the critical cluster size grow to form larger crystals, whereas those with smaller radii undergo dissolution.
Crystal growth occurs when the ratio of concentration and solubility of the solute in the solvent, or the supersaturation ratio, S, exceeds one. Increasing the solute concentration through solvent evaporation or decreasing the solubility of the solute by reducing the temperature increases the value of S.
Crystallization is commonly used for manufacturing active pharmaceutical ingredients.&#160;

kristalgroei: principes van kristallisatie

Crystal Growth: Principles of Crystallization

Kristallisatie is een fase transformatieproces waarbij kristallen worden neergeslagen uit een oververzadigde oplossing of uit andere bronnen worden gevormd. Tijdens kristallisatie rangschikken atomen of moleculen zichzelf in een goed gedefinieerd, stijf kristalrooster om de energie te minimaliseren.

Het initiëren van kristallisatie omvat het manipuleren van de concentratie van de opgeloste stof en de temperatuur van de oplossing. Omdat kristalgroei optreedt wanneer de verhouding tussen concentratie en oplosbaarheid van de opgeloste stof in het oplosmiddel, de oververzadiging verhouding, S, groter is dan één, moet de oplossing worden geconcentreerd en moet de temperatuur laag genoeg zijn. Omdat kristallisatie actief plaatsvindt, verhoogt het verhogen van de concentratie van de opgeloste stof door verdamping van het oplosmiddel of het verlagen van de oplosbaarheid van de opgeloste stof door het verlagen van de temperatuur, de waarde van S, wat het proces bevordert. Een andere belangrijke factor bij de kristalgroei is de afkoelsnelheid, die een essentiële rol speelt in de grootte en morfologie van de kristallen. Langzame afkoeling leidt tot grotere kristallen, terwijl snelle afkoeling resulteert in kleine kristallen.

Het fysieke kristallisatieproces omvat twee stappen: kiemvorming en kristalgroei. Tijdens kiemvorming initieert het oplosmiddel de willekeurige accumulatie van de opgeloste moleculen, waardoor clusters worden gevormd die uiteindelijk het eerste kristal vormen dat de kern of het zaad wordt genoemd. Als kristalkernen worden gevormd uit een oplossing die geen al bestaande kristallen bevatten, worden ze primaire kiemvorming genoemd. Primaire kiemvorming vindt plaats via homogene of heterogene mechanismen. Tijdens heterogene kiemvorming vormen de kristallen zich op oppervlakte-actieve stoffen zoals stofdeeltjes. Aan de andere kant vindt homogene kiemvorming plaats, in een heldere oplossing zonder heterogene deeltjes. Bij secundaire kiemvorming vindt groei plaats vanuit ouderkristallen zoals die welke door middel van zaaien worden geïntroduceerd. Tijdens de tweede fase van kristallisatie, kristalgroei, sluiten steeds meer opgeloste moleculen zich aan bij de stijve roosterstructuur van het zaad, waardoor uiteindelijk de kristalgrootte toeneemt tot macroscopische schaal. Zodra de kristallen zijn gevormd en de oplossing is afgekoeld tot kamertemperatuur, wordt de oplossing gefiltreerd met behulp van vacuümfiltratie en worden de gescheiden kristallen gedroogd en opgeslagen.

Kristallisatie wordt vaak gebruikt als scheidings- en zuiveringsstap in de farmaceutische en chemische industrie. Het wordt ook vaak gebruikt in de voedingsindustrie om suiker, zout, kunstmatige zoetstoffen en andere kristallijne smaakmakers te vervaardigen.

Kristalgroei: principes van kristallisatie

Crystallization is a phase transformation process in which crystals are precipitated from a supersaturated solution or formed from other sources. During ...

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crystal formation through supersaturation

Crystal formation through supersaturation begins when a solution contains more dissolved solute than it can normally hold. In crystallization, atoms or molecules line up into a rigid crystal lattice so the system can lower its energy. To start the process, the solute concentration and the solution temperature must be adjusted so the supersaturation ratio, S, is greater than one.

Supersaturation can be increased in two main ways. One method is to concentrate the solution by evaporating the solvent. Another method is to lower the temperature, which reduces the solubility of the solute. Cooling rate also matters. Slow cooling usually produces larger crystals, while rapid cooling tends to form smaller ones.

Crystallization happens in two stages: nucleation and crystal growth. During nucleation, solute molecules gather into small clusters until the first crystal, called the nucleus or seed, appears. If the nuclei form in a solution with no pre-existing crystals, the process is primary nucleation. Primary nucleation can be homogeneous in a clear solution or heterogeneous on particles such as dust.

In secondary nucleation, growth begins from parent crystals, such as those added during seeding. During the crystal growth stage, more solute molecules attach to the rigid lattice of the seed, making the crystal larger. After the crystals form and the solution returns to room temperature, the mixture is filtered by vacuum filtration. The crystals are then dried and stored.

This separation method is widely used in the pharmaceutical and chemical industries. It also has major uses in the food industry. Sugar, salt, artificial sweeteners, and other crystalline seasonings are often made this way.

Crystal Formation Through Supersaturation

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Crystal formation through supersaturation begins when a solution contains more dissolved solute than it can normally hold. In crystallization, atoms or molecules line up into a rigid crystal lattice so the system can lower its energy. To start the process, the solute concentration and the solution temperature must be adjusted so the supersaturation ratio, S, is greater than one. Supersaturation can be increased in two main ways. One method is to concentrate the solution by evaporating the...

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key terms and concepts

Learn how supersaturation, cooling rate, nucleation, and crystal growth shape crystal formation, and why crystallization is used to separate and purify materials.

Crystal Formation Through Supersaturation | JoVE K12

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Crystal Formation Through Supersaturation

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