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Bioplastics: a clean alternative?

Can waste be turned into bioplastics?

Pure research Richard Robert, Journalist and Author
On February 2nd, 2021 |
3 mins reading time
Can waste be turned into bioplastics?
Grégory Nocton
Grégory Nocton
CNRS Research fellow in synthetic chemistry at École polytechnique (IP Paris)
Grégory Danoun
Grégory Danoun
CNRS Research fellow in synthetic chemistry at École polytechnique (IP Paris)
Key takeaways
  • Synthetic chemists Grégory Nocton and Grégory Danoun are developing new techniques for creating polymers from waste.
  • By isolating the basic building blocks of almost any substance, their current goal is to identify the best synthetic processes for producing these new materials.
  • They opted for waste as a sustainable resource that does not create competition with other processes.
  • The aim is to develop a range of solutions, so as not to be shackled to one, as with petroleum.

In the 20th cen­tu­ry, the avail­abil­i­ty of petro­le­um led organ­ic chemists to focus on a sin­gle source. The rise of bio-sourced mate­ri­als has widened the scope of research impact­ing the indus­tri­al sec­tor. Syn­thet­ic chemists Gré­go­ry Noc­ton (Insti­tut poly­tech­nique de Paris) and Gré­go­ry Danoun (CNRS) are turn­ing their atten­tion to waste. 

You are work­ing on new meth­ods of chem­i­cal syn­the­sis using raw mate­ri­als such as waste. How do these dif­fer from petroleum? 

Gré­go­ry Noc­ton. Indus­try stake­hold­ers would start by telling you about the avail­abil­i­ty of petro­le­um, its homo­gene­ity, vis­cos­i­ty and that of its deriv­a­tives. But for us chemists, the real dif­fer­ence lies in the sim­plic­i­ty of petro­le­um prod­ucts ver­sus the com­plex­i­ty of raw mate­ri­als such as food waste, wood chips and used plas­tic pack­ag­ing. The mol­e­cules in these mate­ri­als are rad­i­cal­ly different. 

Gré­go­ry Danoun. In chem­istry, we have a per­fect under­stand­ing of how to man­u­fac­ture poly­mers from petro­chem­i­cals, so basic research in this area presents few chal­lenges. But with raw mate­ri­als such as waste, we are using dif­fer­ent chem­i­cal reac­tions and a dif­fer­ent approach – so it is far more exciting! 

You are look­ing for ways to pro­duce poly­mers from waste. What is your approach? 

GN. In prin­ci­ple, chemists can break down any mate­r­i­al into its basic build­ing blocks, which can then be used as raw mate­ri­als. Alter­na­tive resources such as waste help us iso­late new build­ing blocks, from which we can syn­the­size new poly­mers with new and use­ful properties. 

GD. Biol­o­gists and micro­bi­ol­o­gists have already been explor­ing this using bac­te­ria and enzymes in process­es such as fer­men­ta­tion, open­ing up avenues of research. The role of chemists here is key. We need to under­stand how dif­fer­ent mol­e­cules in waste gen­er­ate chem­i­cal reac­tions. The fact that there are so many reac­tions just makes things more interesting! 

Wood waste, for exam­ple, con­tains a nat­ur­al poly­mer, lignin, which is also found in cere­al and paper waste. Food waste also con­tains an incred­i­ble range of mol­e­cules, with acids or fat­ty acids and so on. 

To extract use­ful mol­e­cules, we might break down car­boxylic acids, leav­ing us with the basic build­ing blocks, plus hydro­gen. This means oppor­tu­ni­ties for hydro­gen pro­duc­tion (we recent­ly obtained fund­ing for a strate­gic hydro­gen project). The build­ing blocks them­selves can also be used. 

Why not replace petro­le­um with some­thing like starch or sug­ar rather than waste? 

GN. Two rea­sons. First­ly, there is already a lot of indus­tri­al R&D into starch and sug­ar, they are now very much main­stream. Hence, if we want to offer some­thing new, we have to look into more com­plex problems. 

Sec­ond­ly, starch is main­ly made from corn and requires a lot of water. If we made poly­eth­yl­ene tereph­tha­late (PET) from corn, giv­en glob­al demand for plas­tic bot­tles, we would quick­ly run up against a resource prob­lem – and we’re not even address­ing com­pet­ing demand from the food sec­tor. It makes more sense to work with resources that will remain struc­tural­ly available. 

What can we expect in this area in the future? 

GD. Find­ing new ways of obtain­ing basic build­ing blocks is a fas­ci­nat­ing and fast devel­op­ing field. Some of the most inter­est­ing dis­cov­er­ies in the past ten years or so have been made in pho­to­chem­istry, where numer­ous process­es are com­bined using light. We are cre­at­ing reac­tions, try­ing to find new mul­ti­pur­pose catal­y­sers or, on the con­trary, high­ly spe­cif­ic ones aimed at one mol­e­cule in a stack of waste (anal­o­gous to high­ly spe­cif­ic enzymes in biology).

GN. We’re now try­ing to devel­op a wide range of meth­ods, and to break down sci­en­tif­ic bar­ri­ers. Diverse sources of raw mate­ri­als mean more sus­tain­able pro­duc­tion. We want to explore and uncov­er all pos­si­bil­i­ties. If we nar­row our focus, we could end up recre­at­ing the same prob­lems we now have with petro­le­um. Had we done this a hun­dred years ago the world would look very dif­fer­ent today!