Dry Wash

Ion Exchange Resins & Dry Wash Towers

Traditional biodiesel purification primarily utilized water washing to remove impurities. However, the water-centric approach has its drawbacks, such as wastewater generation and emulsification issues. Enter dry wash towers and ion exchange resins: these innovative methods offer a waterless solution to biodiesel purification, ensuring a higher-quality product with fewer environmental concerns.

Ion Exchange Resins

What are they? Ion exchange resins are polymers that can exchange specific ions within the polymer with ions in a solution that is passed over them. In biodiesel purification, they replace contaminants with harmless ions.

Application in Biodiesel Purification:

  • Soap Removal: Ion exchange resins effectively remove soap, a common byproduct in biodiesel production.
  • Catalyst Removal: Residual catalysts, often acidic or alkaline, are neutralized and captured by the resin.
  • Water & Methanol Removal: They can help in removing traces of water and methanol.


  • No Water Required: They eliminate the need for water in the purification process.
  • High Purity Levels: They can achieve more consistent and higher biodiesel purity compared to traditional methods.
  • Reduced Waste: Minimal wastewater generation reduces environmental impact and treatment costs.

Dry Wash Towers

How do they work? Dry wash towers are vessels filled with a specific type of absorbent material. As biodiesel is passed through these towers, impurities are absorbed by the material, leaving purified biodiesel to exit the tower.

Absorbent Materials Used

  • Ion Exchange Resins: These resins, when used in towers, can act as absorbents for impurities.
  • Natural Absorbents: Materials like diatomaceous earth or cellulosic materials can also be used.

Application in Biodiesel Purification

  • Removing Glycerin and Soaps: These impurities get adsorbed onto the tower material.
  • Eliminating Trace Methanol: Residual methanol is also captured as biodiesel passes through.


  • Water Conservation: The process doesn’t use water, thus conserving resources and avoiding wastewater issues.
  • Improved Biodiesel Quality: Consistent quality and higher purity levels are achieved.
  • Ease of Use: The setup is straightforward, and operations can be more comfortable than water wash systems.

Considerations for Using Ion Exchange Resins & Dry Wash Towers

  • Regeneration: Over time, ion exchange resins get saturated and require regeneration, which can be a process involving chemicals.
  • Initial Costs: The setup for dry wash towers, especially those using specialized resins, can have higher initial costs compared to traditional water wash systems.
  • Resin Selection: Depending on the impurities present, selecting the appropriate resin type is crucial for optimal purification.


Ion exchange resins and dry wash towers represent a leap forward in biodiesel purification. By sidestepping the complications of water washing, these methods offer a more sustainable, efficient, and effective means of producing high-quality biodiesel.