It sounds like they are causing incomplete burning of the plastic to generate the wax molecule. They say it may be financially viable because of the value of a tonne of plastic vs a tonne of soap, but do you not lose some of the weight by burning it? What about the conversion from the wax to soap?

What biproducts are being created here from the burning? Probably some form of gas? Carbon dioxide?

The soap that is created, is this biodegradable?

Does the process lead to incomplete conversion, creating soap full of microplastics?

It seems to be pretty early stages so the researchers may not even know the answers.

[–] absGeekNZ 1 points 1 year ago

Early stages, but it looks viable from the simplicity of it. That and you don't have to separate out the two types of plastic that they tested on.

The "burning" is in a sealed environment using "temperature-gradient thermolysis"; this is a type of thermal degradation that doesn't introduce oxygen but uses heat directly. Similar to how a cracking tower works in the conversion of crude -> useful hydrocarbons. Really the burning in the article was used as a metaphor.

Biodegradability will depend a lot on the final product that is being made, this process makes a precursor chemical phase.

There will almost certainly be incomplete conversion, there will have to be a purification step before it is fed into the next process. The real questions here are:

What percentage contaminant is present?
How hard (costly) is it to purify?
What is the waste product and can it be fed back into the cycle to be re-processed?
What temperature does the thermolysis occur at? (higher = costlier)
What is the temperature gradient? (bigger difference = costlier)
Does running this at higher/lower pressure increase efficiency?
How does this product compare to virgin material from crude oil -> the same precursor?

There are a lot more questions I could come up with, but the fact that the process is relatively simple and can take multiple types of plastic is what I found really exciting.