Building a bigger and better solvent still | Chemical & Engineering News
Volume 95 Issue 13 | p. 8 | Concentrates
Issue Date: March 27, 2017

Building a bigger and better solvent still

Chemists aim to prevent waste and save money with a versatile, safety-conscious midscale automated lab system
Department: Science & Technology
Keywords: green chemistry, distillation, solvent
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These homemade distillation stills offer the benefits of saving money and preventing lab waste.
Credit: Stefan Böhmdorfer
A photo shows a pair of distillation columns in a lab fume hood.
 
These homemade distillation stills offer the benefits of saving money and preventing lab waste.
Credit: Stefan Böhmdorfer
[+]Enlarge
Graduate student Slavica Hell (left) poses with Böhmdorfer and one of their new stills; the automated control panel is shown on the wall at right.
Credit: Courtesy of Stefan Böhmdorfer
A photo of Slavica Hell and Böhmdorfer in front of a pair of distillation columns in a lab fume hood.
 
Graduate student Slavica Hell (left) poses with Böhmdorfer and one of their new stills; the automated control panel is shown on the wall at right.
Credit: Courtesy of Stefan Böhmdorfer

Most labs have a small still for quickly purifying solvents. But for Stefan Böhmdorfer and his colleagues at the University of Natural Resources & Life Sciences in Austria, that wasn’t enough. The researchers carry out a lot of chromatography and realized they had much to gain by purifying and reusing their solvents, rather than paying someone to cart them away for recycling. The team had a hard time finding a commercially available still that could do everything they wanted, including handling between 2-L bench-scale and 30-L pilot-scale amounts, having fully solvent-resistant components, and offering precise control over separating solvent fractions. So the researchers decided to build their own system. That’s not a new idea, but the team spared no detail in designing its system to handle solvents of all polarities and a wide range of boiling points and to collect fractions automatically (Org. Process Res. Dev. 2017, DOI: 10.1021/acs.oprd.7b00007). The researchers built two stills for 6-L batches inside a walk-in fume hood. The basic setup includes a 10-L round-bottom flask, a 100-cm-long/30-mm-diameter packed column, a condenser, drying tubes, and collection vessels. Temperature sensors and electronically controlled valves enable the automated fraction collection and also serve as a safety feature to shut the system down if something starts to go wrong. The distilled solvents are typically of higher purity than the analytical-grade solvents the group was buying. “I am convinced that a lot of research groups are facing the same situation of having larger amounts of easily redistillable solvents and can decide to build their own device,” Böhmdorfer says.

 
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