A solvent is a molecule that has the ability to dissolve other molecules, known as solutes. Solvents can be in the form of a solid, liquid or gas. The molecules of the solvent pull the solute molecules apart.
When this occurs, these molecules become evenly distributed throughout the solvent, creating a homogeneous mixture that cannot be separated physically unless heat or another chemical process is applied.
Here is where solvent distillation systems come into play. Through the application and removal of heat, the solvent distillation process separates a liquid or vapor mixture of two or more substances into its component fractions of desired purity.
How does a solvent distillation unit work and make this process happen? Below we will explore the process, what solvents will work in the unit and how solvent distillation is just one part of a bigger picture that emphasizes sustainability in industry today.
The Process Explained
The solvent distillation recovery process is based on the fact that the vapor of a boiling mixture is richer in low boil point components. After the vapor cools and condenses, the liquid condensate is ready to be sold back into industry.
Here is how a solvent distillation unit works:
- A company will generate and transport its hazardous waste to a solvent distillation facility. After arriving at the facility, a fingerprint analysis is conducted. This identifies the waste and sorts it.
- Liquid drums in the unit are pumped and filtered, after which solvents are pumped to the distillation unit. It is here that volatilized solvent vapors expand into the fractionation column of the unit.
- A heat exchanger cools off the solvent.
- After cooling, solvents are directed to a finished product tank.
- Workers then package the product into drums and totes for distribution back into industry.
There is typically a portion of the original mixture that does not vaporize. This portion remains at the bottom of the recovery still and can be recovered and used as an alternative fuel source in some industries.
A wide variety of solvents are acceptable for use in a solvent distillation unit. This allows several different types of manufacturers to take advantage of this sustainable process.
The most commonly recycled solvents used in a solvent distillation unit include:
- Aliphatic: Mineral spirits and naphthas
- Aromatics: Toluene and xylene
- Halogenated hydrocarbons: Fluorocarbons, methylene chloride, perchloroethylene, trichloroethylene and 1,1,1 trichloroethane
- Alcohols: Isobutyl alcohol, isopropyl alcohol, N-butyl alcohol and methanol
- Ketones: Acetone, methyl isobutyl ketone and methyl ethyl ketone
- Esters: Ethyl acetate
Other solvents can be found in our eBook, Acceptable Waste Codes Guide. This eBook provides a complete list of acceptable waste codes Temarry Recycling receives to give you a better idea of whether your facility can take advantage of solvent distillation.
At Temarry Recycling, solvent distillation is one component of a Closed Loop Recycling system that ensures nothing is wasted.
This full-circle system combines solvent distillation with a waste to energy process and water treatment process.
Here’s how it works:
- The waste to energy process converts high BTU organic solids to steam to be used as energy on-site.
- The solvent distillation process uses the steam from the waste to energy process as energy to power the solvent recovery stills. Spent solvents are re-manufactured and sold back into industry for their original solvent properties.
- The water treatment process extracts usable water from industrial hazardous wastes. This treated water is used on-site for industrial needs, including the waste to energy equipment and a cooling tower.
Compared to an open loop system, a closed loop system keeps materials at their highest utility and value always. A closed loop is restorative and regenerative by design, whereas an open loop system typically recycles materials that are then used for a different purpose.
Although solvent distillation can play an important role in returning solvents back to industry, when it is part of a closed loop recycling system, this process plays an even stronger role in reducing hazardous waste and keeping materials at their highest value.
Advantages In Industry
Sustainable companies have an advantage in industry, and the solvent distillation process offers many of these same benefits.
For example, incorporating sustainable practices like solvent distillation can improve a company’s image, help a company stay ahead of ever-changing federal and state regulations, and save costs. In fact, contrary to what some believe, sustainable practices help conserve resources, which leads to a reduction in costs.
For companies looking for ways to achieve high levels of sustainability and have an advantage in their industries, solvent distillation may be one of the most cost-effective and environmentally-friendly methods.