A greener processing method could make metal-organic frameworks (MOFs) more practical for removing heavy metals from industrial wastewater, according to researchers at the University of Birmingham. The team found that freeze-drying a previously developed water-based MOF increased material yield, reduced estimated energy demand and lowered estimated production costs while maintaining the material’s lead-removal performance.

The MOF was developed to recover rare earth elements and heavy metals from industrial waste streams. Unlike conventional MOF production methods that can require substantial solvents or energy, the Birmingham team’s approach uses a scalable water-based process. The resulting material is produced as pellets rather than fine powder, making it easier to handle in wastewater-treatment applications. Tests using real-world water samples showed effective lead removal with low copper leaching.

In the latest work, published in Green Chemistry, researchers led by Swaroop Chakraborty evaluated freeze-drying as a post-processing step. The technique increased isolated yield more than threefold and reduced estimated electricity demand per gram by about 74%. Estimated lab-scale production costs fell from about $19/g with conventional processing to just over $5/g.

The freeze-dried material also removed more than 90% of lead from solution within the first hour and maintained high removal performance across four consecutive treatment batches. The material retained its principal structural features after seven days of exposure to air, freshwater-like conditions and artificial seawater.

The researchers are seeking industrial partners in mining, electronic waste and water treatment to license the technology for specific applications or co-develop pilot-scale trials under real-world conditions. University of Birmingham Enterprise has filed a patent application covering the method.