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Difference between Coprecipitation and Post Precipitation

Last updated date: 04th Mar 2024
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What is Coprecipitation and Post Precipitation: Introduction

Coprecipitation and post-precipitation are two phenomena that occur during the precipitation process in chemistry. Precipitation refers to the formation of solid particles from a solution due to the interaction of solutes with solvents or changes in temperature or concentration. Both coprecipitation and post-precipitation have practical implications in various fields, ranging from environmental monitoring to pharmaceutical research.

Coprecipitation: Coprecipitation happens when impurities or secondary components are incorporated into the precipitate along with the desired primary component. It occurs when these impurities are present in the solution and are trapped within the growing solid particles during the precipitation process. This phenomenon can significantly impact the purity and composition of the final precipitate.

Real-Life Example: An example of coprecipitation in real life can be seen in water treatment processes. When treating contaminated water to remove pollutants, such as heavy metals or organic compounds, precipitation techniques are often employed. During this process, metal ions or other impurities present in the water can become incorporated into the formed precipitate, reducing the effectiveness of the treatment. This unintentional coprecipitation can hinder the purification process and may require additional steps to remove the impurities and obtain a pure precipitate.

Post-Precipitation: Post-precipitation refers to the occurrence of precipitation reactions that take place after the initial formation of the primary precipitate. It happens when the conditions of the solution change, such as pH or temperature, leading to the formation of new solid particles. These particles can be different in composition from the primary precipitate and can significantly impact the final product.


Real-Life Example: In pharmaceutical synthesis, post-precipitation can occur during the purification and isolation of a desired drug compound. After the initial precipitation step, additional purification steps are often performed to remove impurities. These subsequent steps can involve changing the pH or temperature, which can induce post-precipitation reactions. The newly formed precipitates may consist of unwanted byproducts or impurities that need to be separated from the desired compound.

Understanding the concepts of during post precipitation is crucial for controlling the purity and composition of precipitated materials in various scientific and industrial processes. By studying these phenomena, scientists and researchers can develop strategies to mitigate the impact of impurities and optimize the precipitation processes for improved product quality.

Characteristics of Coprecipitation and Post Precipitation

Coprecipitation and post-precipitation are two distinct phenomena that occur during the precipitation process in chemistry. Understanding their characteristics is essential for controlling and optimising precipitation reactions.

Here are the key characteristics of coprecipitation and post-precipitation:

For Coprecipitation: 

Impurity Incorporation: Coprecipitation involves the incorporation of impurities or secondary components into the precipitate along with the desired primary component.

Simultaneous Precipitation: Impurities are present in the solution and are trapped within the growing solid particles simultaneously with the primary component's precipitation.

Influence on Purity: Coprecipitation can reduce the purity of the final precipitate, as impurities become incorporated into the solid structure.

Challenging to Control: Controlling coprecipitation can be challenging, as it depends on factors like the concentration of impurities, the rate of precipitation, and the physical properties of the precipitate.

Common in Complex Systems: Coprecipitation is more likely to occur in complex systems with multiple components, where interactions between different ions or molecules lead to impurity incorporation. 

For post-Precipitation: 

Secondary Precipitation: During post precipitation the formation of new solid particles after the initial primary precipitate has formed.

Changes in Solution Conditions: Post-precipitation occurs due to changes in solution conditions such as pH, temperature, or concentration, which induce the formation of new solid phases.

Different Composition: The newly formed precipitates in post-precipitation can have a different composition from the primary precipitate, leading to the presence of unwanted byproducts or impurities.

Impact on Product Quality: Post-precipitation can significantly impact the final product's purity, composition, and physical properties.

Controllable with Process Optimisation: By carefully controlling the conditions of the solution and precipitation parameters, post-precipitation can be minimized or eliminated to obtain a pure and desired precipitate.

Understanding the characteristics of coprecipitation and post-precipitation is crucial for researchers and scientists involved in various fields such as materials science, pharmaceuticals, environmental analysis, and chemical synthesis. By considering these characteristics, strategies can be developed to minimize impurity incorporation and optimize the precipitation process for desired product properties.

Applications of Coprecipitation and Post Precipitation

Coprecipitation and post-precipitation have numerous applications across various fields.

  • Coprecipitation is widely used in materials science for the synthesis of solid solutions, where desired elements are incorporated into the crystal lattice of a host material. This technique is valuable for tailoring the properties of materials, such as magnetic, optical, or catalytic properties. 

  • Coprecipitation is also employed in environmental science for the removal of pollutants from water or wastewater. By precipitating the pollutants along with suitable precipitating agents, their concentration can be significantly reduced.

  • Post-precipitation techniques are utilized to modify the properties of precipitates. For example, calcination can be used to enhance the crystallinity and stability of precipitates, while chemical reactions can be employed to introduce new functionalities or alter the composition of the precipitates.

Both coprecipitation and post-precipitation techniques play crucial roles in the development of advanced materials, environmental remediation, and the synthesis of functional nanoparticles with tailored properties.

Difference between Coprecipitation and Post Precipitation

S. No. 



Post Precipitation



Simultaneous precipitation of primary component and impurities

Formation of new solid particles after primary precipitation


Purity of Precipitate

Reduction in purity due to impurity incorporation

May affect the purity and composition of the final product 


Impurity Incorporation

Impurities are incorporated into the primary precipitate

New solid particles have different composition from the primary



Challenging to control due to complex factors

Controllable through optimization of solution conditions 



More likely in systems with multiple components

Can occur in various systems with changes in solution conditions


Coprecipitation and post-precipitation are techniques used to modify precipitates for various purposes. Coprecipitation involves the simultaneous precipitation of two or more substances, resulting in the incorporation of one substance into the crystal lattice of the other. This technique is commonly used to achieve solid solutions, doping, or to remove impurities from a solution.

On the other hand, post-precipitation refers to the modification of a precipitate after its formation. It involves subsequent treatments such as calcination, annealing, or chemical reactions to alter the composition, structure, or properties of the precipitate.

Both coprecipitation and post-precipitation offer control over the final characteristics of the precipitate, making them valuable in various fields, including materials science, chemistry, and environmental science.

FAQs on Difference between Coprecipitation and Post Precipitation

1. What is the difference between coprecipitation and post-precipitation?

Coprecipitation refers to the simultaneous precipitation of two or more substances from a solution, resulting in their incorporation into a solid precipitate. In contrast, post-precipitation involves subjecting a primary precipitate to additional treatments or reactions to modify its properties or achieve further purification.

2. How do coprecipitation and post-precipitation affect the composition of precipitates?

Coprecipitation can lead to the inclusion of impurities or other substances in the precipitate, altering its composition. In post-precipitation, subsequent reactions or treatments can result in the formation of new compounds or the removal of impurities, leading to a modified composition of the precipitate.

3. What are the advantages of coprecipitation and post-precipitation in various applications?

Coprecipitation offers advantages such as simultaneous removal of multiple contaminants, efficient purification, and controlled synthesis of composite materials. It is beneficial in environmental remediation, pharmaceutical formulation, and nanoparticle synthesis. Post-precipitation allows for further modification, purification, or tailoring of precipitates, offering advantages in catalyst preparation, material science, and waste treatment applications. It enables researchers to fine-tune the properties of precipitated materials and achieve specific desired characteristics.