Solid-Liquid Extraction Leaching

Solid-Liquid Extraction Leaching

Leaching is a process that involves removing substances from a solid by way of a liquid. This liquid is better known as a solvent—a chemical substance that is used to dissolve other substances.

Although you may not be familiar with the details of leaching, you likely engage with this extraction method on a daily basis, or at least use products with ingredients that come from leaching. For example, many edible oils such as sunflower seed oil, olive oil, and more are possible with solid-liquid extraction, otherwise known as leaching.

The Process of Leaching

Water is known as the “universal solvent,” since it does an excellent job of dissolving a variety of substances. We use water every day, and many of us every morning when we brew our morning cup of coffee or tea. The hot water we combine with coffee grounds extracts the caffeine and other materials from the grounds to successfully make our morning cup of joe. This is a great example of leaching in our everyday lives.

The following factors influence the rate of extraction:

  • Particle size of the solid
  • Solvent used
  • Temperature of the solvent
  • Agitation of the fluid 

In most cases, a high temperature is necessary to facilitate a faster chemical reaction. However, some products undergo leaching in cold fluids. Cold brew coffee is likely the most well-known example, where coffee grounds sit in cold water for about 20 hours.

Solvents Used for Leaching

While water is a great solvent for extraction, it isn’t the only one. There are a variety of solvents that extractors can choose to use depending on the substance they are trying to extract.

One of the most popular industrial leaching processes is the extraction of cannabidiol (CBD) and other compounds from cannabis plants. Once removed, CBD and other desirable compounds are used as additives in lotions, tinctures, beauty products, and much more.

Here are a few of the most common solvents used for industrial leaching:

  • Butane
  • Propane
  • Ethanol
  • Acetone
  • Methanol
  • n-Hexane

For extracting substances from metals, higher strength solvents such as sodium hydroxide or potassium cyanide are used.

Looking to Purchase Supplies?  

If you’re preparing to leach any substance, Extraction Grade Solvents can provide you with the products you need! Browse our website to view our extensive inventory of solvents available to buy in bulk. Choose from 5-gallon to 55-gallon pail options, which will help cut down on packaging waste, bringing your company closer to zero waste.

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