Solvent Extraction vs. Solvent Distillation

Do you know the difference between solvent extraction and solvent distillation? Learn the basics of these two processes of chemical recovery.

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Solvent extraction is an extremely important process in many of today’s industries. It’s also a common method used to separate and purify elements, proving this process a helpful way to recovery different chemical components.

One of the most prominent industries to use solvent extraction is petrochemical refining. Petroleum that has been extracted comes with a lot of impurities and debris. In order to use petroleum, it has to be cleaned or extracted to purify the product using a special solvent.

What is Solvent Extraction?

Solvent extraction is a method where chemical compounds are isolated based on their solubilities. This process requires using a particular solvent in the form of fluid to separate and dissolve another substance.

Solvent extraction is used in many different industries from food to vegetable oils, perfume to manufacturing, mining to processing of minerals, pharmaceuticals, and cosmetics. The main purpose of solvent extraction is to isolate hazardous materials from the sediments and sludge or separate the useful components from debris. For instance, solvent in the petrochemical refining industry is applied to separate petrol impurities either by making them float or sink to the bottom for easy removal.

Solvent extraction is especially useful in the hazardous waste industry as this process will reduce the amount of hazardous waste that needs to be treated. Keep in mind that solvent extraction does not damage the compound extracted. All it does is separate compounds. Each compound is then extracted to be used for its various purposes depending on the industry.

What is Solvent Distillation?

Solvent distillation is the process of separation that involves the application of heat to separate liquid mixture of two or more substances.

A solvent mixture (spent solvent) is heated to the boiling point of the solvent. As a vapor, it’s then piped away to a new storage container where it will cool and re-condense to near virgin quality.

When the process is finished you are left with a pure, distilled solvent that can be reused. In the other container you’ll be left with the waste that must be disposed of accordingly.

Solvent distillation machines come in a variety of sizes, from small units that connect to just a few drums to massive facilities. While they may function a little differently based on size, their core components are essentially the same.

solvent waste and distillation machine

How Does Extraction Compare to Distillation?

The biggest difference between these two processes is this:

  • Solvent extraction: It purifies a substance whether it is in its liquid or solid phase
  • Solvent distillation: It purifies a substance only in its liquid phase

Applications of Distillation and Extraction

Distillation is commonly used in the petroleum industry and in the solvent industry. For instance, distillation is the favored method to separate acetic acid from acetone, benzene from toluene, and methanol and ethanol from water.

Extraction is commonly used in industries such as pharmaceuticals, fragrances, essential oils, and food products. It is the favored method that can safely isolate organic compounds such as nitrated aromatic compounds, phenol, and aniline from water.

Types of Solvent Extraction & Distillation

When it comes to the types of distillation or extraction used, there are many from vacuum to steam. However, the main difference in these types is the way compounds are separated from one another.

In solvent distillation, you have these types of techniques:

  • Vacuum distillation
  • Simple distillation
  • Zone distillation
  • Steam distillation
  • Fractional distillation
  • Air-sensitive vacuum distillation
  • Short path distillation

The most commonly used form of distillation is simple distillation and fractional distillation. The simple distillation process is used when two liquids have different boiling points whereas fractional distillation is used when two liquids have equivalent boiling points.

In the solvent extraction process, the most common types are:

  • Solid-liquid extraction- involves isolating a substance from a solid using a fluid solvent.
  • Liquid-liquid extraction is used to separate a substance from a liquid.

Is Solvent Extraction Environmentally Friendly?

It is extremely crucial for business and industries nowadays to use and adopt environmentally friendly practices in their manufacturing and processing journey. If businesses can adopt environmentally friendly initiatives even in one step of the manufacturing process, that alone can bring immense positive impact to the environment.

The simple answer is using environmentally friendly solvents will make the extraction process eco-friendly. For instance, water is the preferred liquid for environmentally friendly extractions.

As more and more businesses look for green solvent initiatives where water is not the best solution, bio solvents have come to the rescue. Bio solvents are derived from the processing of agricultural crops.

Another benefit of solvent extraction is that it consumes less energy compared to distillation.

Is Solvent Distillation Environmentally Friendly?

That said, solvent distillation when used as a part of the closed loop recycling and recovery system, has its environmental benefits as well. The closed loop recycling and recovery system allows businesses to collect waste to be treated and repurposed into a reusable product again and again.

Some businesses also look for ways to reduce waste produced by the solvent distillation process. For instance, solid wastes can be treated at a 1500-degree thermal magnitude to generate steam. This steam can be repurposed to power up solvent recovery system.

ANOTHER (BETTER) WAY

CleanPlanet partners with its customers to ensure they are maximizing their onsite chemical recycling. Our advanced solvent distillation technology allows our customers to recover more chemical than any other distillation unit. If you’re struggling with an underperforming distillation unit reach out to our team to see how we can help.

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