ENZYMATIC RECYCLING OF WASTE COOKING OILS FOR THE PLASTIC INDUSTRY

Project Information

REWIND

Grant agreement ID: 101031186

DOI

10.3030/101031186

Project closed

EC signature date 29 April 2021

Start date 1 April 2022

End date 31 March 2024

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 171 473,28

EU contribution

€ 171 473,28

Coordinated by

UNIVERSITA DEGLI STUDI DI BARI ALDO MORO
Italy

Periodic Reporting for period 1 - REWIND (ENZYMATIC RECYCLING OF WASTE COOKING OILS FOR THE PLASTIC INDUSTRY)

Reporting period: 2022-04-01 to 2024-03-31

Summary of the context and overall objectives of the project

Plastics are fundamental in our everyday life due to their extreme versatility. They find application in a wide range of fields (e.g. packaging, transport, electronics, construction, agriculture). The term bio-based plastics describes organic polymers that are synthetically or semi-synthetically produced from biomass. Globally, only 1% of the 300 Mton/y of produced plastics comes from renewable resources. The market of bio-based plastics is increasing and it is estimated that in 2030 40% of the entire plastic production will be covered by bio-based plastics. Although, common bio-based plastics are thought to be biodegradable, recent studies on industrial and domestic compostability have shown differences in the biodegradation of specific bioplastics, such as Polylactic acid (PLA).
Buio-based plastics are commonly produced from virgin resources, that could increase the overexploitation of soils and the loss of biodiversity.
The use of renewable resources derived from by-products and waste could be of great interest for the society in order to improve the presence of sustainable alternatives that could reduce the need for virgin resources. According to circular economy, it is necessary to valorize waste products to encourage their further potential, instead of using them for bioenergy and biofuels. Use of renewable materials from waste can improve the sustainability of bio-based plastics. Vegetable oils, and in particular WCO, represent a promising feedstock for sustainable chemicals and polymeric structures due to their high availability and biodegradability. Cooking oils contain saturated and unsaturated fatty acids in the form of triglycerides. After their end-of-life, WCO are either disposed of or transformed into biofuel through physical and or chemical approaches, such as esterification and hydroprocessing. Enzymes possess high specificity and act at milder conditions compared to commonly used metal catalysts. Enzymatic transformation, in one-pot reactions, can reduce the use of harsh chemicals and the production of by-products, which means less need for further purification.

The REWIND project have the following objectives:
• O1: Multistep biocatalytic synthesis of hydroxy fatty acids and their oligomers and polymers.
• O2: Chemical, physical, mechanical and biological characterization of the oligomers and polymers.
• O3: Sustainability assessment to evaluate the environmental impact of the product’s life compared to that of
chemically produced polymers and biodiesel production.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The project allowed the valorization of waste cooking oils (WCO) into polymers through different approaches.
The main steps of the valorization was the enzymatic transformation of waste cooking oils into hydroxy fatty acids. In order to do that the feedstock was first studied for the possibility to be transformed into hydroxy fatta acid compared to other feedstocks and if any contaminants present in the mixture could hinder the activity of certain enzymes.
in order to do so, a chemo-enzymatic approach was carried out to transform WCO into the following intermediates:
- Chemical hydrolysis for the production of free fatty acids
- Enzymatic hydration for the production of saturated and unsaturated hydroxy fatty acids
- Chemical hydrogenation for the reduction of unsaturated hydroxy fatty acids into saturated hydroxy fatty acids
- Chemical esterification for the production of hydroxy fatty acid methyl esters
- Chemical polymerization for the production of the polyester poly(10-hydroxy stearic acid) methyl ester

The next step of the process was the identification of the optimal conditions for the creation of a one-pot hydrolysis-hydration reaction using a lipase and hydratase enzymes. This approach was used and optimized through design of experiment (DoE) to improve the feasibility of the work.
After the identification of the conditions for the hydration reactions by the Escherichia coli whole-cell biocatalyst containing the recombinant Oleate hydratase from Elizabethkingia meningoseptica, the one-pot enzymatic cascade reaction was carried out in the presence of the enzyme Candida rugosa lipase, which is a well-known lipase for the hydrolysis of triglycerides.
The experiments allowed to identify the differences of yield using different feedstocks (WCO, olive pomace oil, sunflower oil, olive oil and olive mill wastewater), identifying different perfomance for biocatalytic transformation and production of hydroxy fatty acids.
These 2 approaches were used and compared to assess their sustainability.

The hydroxy fatty acids produced from the enzymatic transfomation of WCO were compared to the hydroxy fatty acids which are present in castor oil to identify differences in performance for polymerization reactions.
The use of enzymes as catalyst for polymerization reaction allowed to produce specific polymers. In particular polymers from castor oil and from WCO were able to be produced with enzymes and with the conventional catalyst dibutyltin oxide.
The polymers produced were characterized by their thermal properties and for the biodegradability to identify possible applications in the plastic industry.
Moreover, from castor oil we were able to produce unsaturated polyesters which are able to be further modified to permit the production of thermosets.
The latter were produced using a thiol-ene reaction using a photoinducer and UV light. This enabled the production of specific thermosets and further characterization by chemical, thermal and hydrophobiciy analysis.

The hydroxy fatty acids were also used to produce fatty acid starch esters that are currently used as packaging materials.
This process used native potato starch as polymer for the grafting of fatty acids and hydroxy fatty acids for the production of different materials which contained a different degree of substitutions which allowed the production of specifc features.
The materials were tested for the chemical, thermal and hydrophobicity analysis.


The researcher has founded a start-up company (REWOW srl) which is currently working on the exploitation of the results.
The Dissemination of the results was carried out during scientific conferences (such as IFIB 2022, IFIB 2023 and BIOCAT 2022) and during outreach activities (such as the European Researchers' Night, MakerFaire 2022 and MakerFaire 2023). Moreover the researcher requested services from the European Results Booster for Dissemination and Exploitation activities.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The use of waste resources is of high interest which could have great socio-economic impact.
Waste cooking oils (WCO) are renewable resources and their use for the production of different project is of great interest.
Other European projects (e.g. Waste2Func) are using this feedstock for the production of surfactants by microbial fermentation and the production of companies for the commercialization of these materials.
This shows a great interest for the society and the economy on the use of waste resources to produce molecules and products which could be included in circular bioeconomy and on industrial symbiosis models.
The identification of the need for certain feedstocks, such as WCO, can be of great importance to improve the collection of these materials and to reduce the negative impact that these by-products could have on the environment and on the economy.

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