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Comment by buildsjets | Hacker News Reader

Wait up. They propose to convert DDT trapped in the soil to benzene trapped in the soil? Is not benzene also a toxic and persistent soil pollutant (it is) where the typical remediation is to excavate the bad soil and landfill it? (it is)

https://www.waterboards.ca.gov/water_issues/programs/gama/do...

There was an old lady who swallowed a fly, she didn’t know why.

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Benzene is far more degradable than DDT. In fact the primary reason benzene causes cancer is because the human liver can metabolize it, producing the reactive carcinogen oxepin. It doesn't always degrade fast enough to prevent toxicity to humans or animals, but it doesn't last forever.

They're not leaving it in the soil. The benzene is extracted as a useful byproduct.

Yes, they are leaving it in the soil. Prove me wrong with data. It says nothing at all about extracting the waste benzene they created from the soil, neither in the linked article nor in the complete paper, which i did read. The paper specifically describes an in-situ process. If it were economically beneficial to extract benzene from contaminated soil for industrial use, we would already be doing that with the tens of thousands of existing benzene contaminated sites, not creating more of them.

> neither in the linked article nor in the complete paper, which i did read.

I'm having trouble finding the paper, can you link please?

Courtesy of another poster down-thread.

https://ethz.ch/content/dam/ethz/special-interest/chab/organ...

Isn't this the 2021 paper?

I can't find the 2025 which this article is supposed to be improving upon that work?

Or are we just resurfacing 2021 work all together?

[Edit]

Yes that is the 2021 paper, but this new announcement is supposed to improve that process but I can't find any sort of paper other than the Spark Award 2025 announcement[0]

[0] https://www.youtube.com/watch?v=NcMTOI25yb8

It's in the article:

> The reactor used by the researchers consists of an undivided electrolysis cell in which dimethyl sulfoxide (DMSO) is used as a solvent

They move the DDT from the soil to the solvent, which is the medium for electrolysis, not the soil itself.

> A much lower Lindane-soil ratio of 1 w%, where Lindane was extracted with the reaction solvent prior to the degradation, also afforded good yields for both benzene (76%) and dichloride (76%, Entry 4, Fig. 4D). This alternative pre-extraction protocol acts as a further proof-of-concept which might help the design of larger scale remediation processes in which undesired soil contamination with electrolyte and Mn catalyst can be prevented. Interestingly, the large-scale feasibility of an extraction approach has been demonstrated by the successful treatment of ca. 70,000 tons of HCH contaminated soils in the Netherlands in a full-scale soil washing plant, which achieved HCH removal efficiency of more than 99.7% (42).

Emphasis added

The DDT is soluble in DMSO, so it is already possible to separate from soil.

The problem has been that the DDT isn't really useful, so you're still left over with DDT tainted DMSO. Hence, most cleanup efforts focus on sequestration of soil.

The electrolysis step creates benzene and other hydrocarbons, making a useful byproduct. This means there's a better incentive to treat it rather than store it.

So, you’re essentially washing the soil in DMSO, and DDT is more soluble in DMSO? — curious, what does it take to wash all that soil?

Assuming it doesn't break down under electrolysis, the DMSO can be recovered, so you only use as much as you can process at a time.

It is apparently used in some battery chemistries, so I'd expect losses to be pretty low if the equipment is set up well.

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