A dithiocarbamate-modified cellulose material removed more than 99 per cent of lead from methanol effluent and about 91 per cent from DMF, reaching equilibrium within ten minutes.
Most technology for recovering metals from industrial waste assumes the waste is water. Ion-exchange resins, precipitation, adsorption onto activated carbon — the standard toolkit was built for aqueous solutions, and it works reasonably well in them. Organic solvents are a different problem, and a growing one, because an increasing number of manufacturing processes dissolve their metals in methanol, dimethylformamide and similar fluids rather than in water.
A study in ACS Applied Materials & Interfaces from teams at Kanazawa University, Fukushima University and Daicel Corporation reports a sorbent designed for exactly those streams, and tests it on one of the more awkward examples: the effluent left behind when a perovskite solar cell is recycled.
Sulphur that grabs metal
The material, designated DPE6, is cellulose — ordinary plant polysaccharide — chemically modified with dithiocarbamate groups. Dithiocarbamates contain two sulphur atoms arranged to bind metal ions strongly, and the chemistry is well established: dithiocarbamate compounds have been used as metal chelators and in rubber vulcanisation for decades. What is new here is grafting them onto a cellulose backbone to make a solid sorbent that functions in organic media.
The researchers confirmed the binding mechanism with three complementary techniques — infrared spectroscopy, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy — all of which pointed to the sulphur atoms as the site where metal ions are captured. Using three methods to converge on one mechanistic conclusion is good practice, and it matters for a sorbent, because a material that binds metals by an unidentified mechanism is hard to improve deliberately.
Performance against lead and nickel was tested across a range of solvents, and the headline practical figure is speed: sorption reached equilibrium within ten minutes. For an industrial process, contact time translates directly into reactor size and throughput, and ten minutes is fast enough to be compatible with continuous operation rather than requiring long batch soaks. Maximum capacity was highest in pure methanol and in DMF.
Why the solvent itself matters
The more interesting scientific contribution is a systematic study of how metal uptake varies with the type and properties of the surrounding organic solvent, rather than measuring performance in one liquid and declaring success.
That variation is not a nuisance to be averaged away. A solvent competes with the sorbent for the metal ion: a strongly coordinating liquid holds the metal in solution and makes it harder to capture, while a weakly coordinating one effectively hands it over. Solvent polarity, donor strength and the structure of the solvation shell around each ion all enter the calculation. A sorbent that works in methanol may fail in DMF for reasons that have nothing to do with the sorbent.
Which makes the perovskite result the significant one. Testing on lead-containing effluents from recycling used perovskite solar cells, DPE6 removed more than 99 per cent of the lead from methanol-based effluent and about 91 per cent from DMF-based effluent. The release states that commercially available sorbents struggle to achieve sufficient lead removal from DMF-based effluents, which is precisely where this material retained most of its capability.
The perovskite problem, stated plainly
Perovskite solar cells are among the most promising photovoltaic technologies in development, with laboratory efficiencies that have climbed remarkably fast. The highest-performing formulations contain lead. This is the field’s persistent difficulty: a technology intended to decarbonise electricity generation that distributes a potent neurotoxin across rooftops, with a service life after which the modules become waste.
Recycling is the obvious answer, and recycling perovskites generally means dissolving the active layer in an organic solvent — DMF being a common choice. That produces a lead-laden organic liquid which is itself hazardous waste unless the lead can be taken out. A sorbent that pulls 91 per cent of the lead from DMF addresses a bottleneck sitting directly in the path of an environmental technology, which is a more specific claim than most sorbent papers can make.
Ninety-one per cent is not, however, 99.9 per cent. Lead is regulated at low concentrations, and whether a single pass at 91 per cent is sufficient depends on where the stream started and where it has to end up — figures the release does not provide. Multiple passes are possible in principle; the release says nothing about whether the sorbent can be regenerated and reused, which is the economics of the whole approach.
What is disclosed, and what is not
This release is better documented than many on funding and worse on authorship. It names JSPS KAKENHI grants JP23K04094, JP25K22855, JP25H01197 and JP24K15337, and states that expenses for joint research with Daicel Corporation were borne by Daicel. It also discloses that Kanazawa University and Daicel jointly filed an international PCT patent application covering the technology.
That disclosure is worth having and worth noting. The commercial partner funded the research and co-owns a patent application on the result, which is an ordinary arrangement in applied materials chemistry and is exactly the sort of thing readers should be told. There is no formal conflict-of-interest statement, but the substance of one is present.
On the other side, the release names no authors whatsoever — only the three institutions involved. The sole individual listed is a media contact. There are no direct quotations from anyone, so none appear in this article, and the endnote below carries the paper title alone because no first or corresponding author is identified.
Several technical questions remain open. The work covers lead and nickel; the paper’s title speaks of critical metals more broadly, but the release reports no data on the rare-earth and platinum-group elements that term usually denotes. There is no information on selectivity between metals in a mixed stream, which matters if the aim is recovery rather than merely removal — a sorbent that takes up everything produces a mixed sludge, not a product. And no comparison data for the commercial sorbents said to underperform is given, so that claim rests on assertion.
What stands is a fast, mechanistically characterised sorbent built on a cheap renewable backbone, working in the solvents where the existing toolkit does not, demonstrated on a waste stream that a maturing solar technology is about to start producing in volume.
Notes
- “Dithiocarbamate-Functionalized Cellulose for High-Efficiency Separation of Critical Metals from Organic Effluents.” ACS Applied Materials & Interfaces, 8 July 2026. DOI: 10.1021/acsami.6c06734.
- Kanazawa University. “Novel technology for highly efficient recovery of critical metals from organic effluents.” EurekAlert!, 6 October 2026. https://www.eurekalert.org/news-releases/1146681.