Environmental toxicologists from the VU University Amsterdam conclude in the May edition of the journal Green Chemistry that the production of the biochemical substance FDCA from plant waste poses no extra risk to the soil environment in comparison with the current production of PET from petroleum.
The BE-Basic Foundation commissioned Chinese doctoral candidate Guang Chen, together with Nico Van Straalen and Dick Roelofs from the VU University Amsterdam, to examine the toxicity of three substances for the soil environment. These were terephthalic acid (TPA), a fossil raw material for the production of polyethylene terephthalate (PET) and the green raw material-based 2.5-furandicarboxylic acid (FDCA). The third chemical they examined was 5-hydroxymethylfurfural (HMF), which is required as an intermediate substance for the synthesis of FDCA.
Not toxic
According to Van Straalen, the results of the soil research show that FDCA and TPA are not toxic in normal soils. The environmental toxicologist believes that the risk for the soil comes mainly from the intermediate 5-hydroxymethylfurfural (HMF), which is formed during the synthesis of FDCA. HMF induces a large number of biotransformation enzymes in the micro organism, an indication of the conversion to a reactive intermediary product. HMF fortunately has a very short half life: the microorganisms break the chemical down within two days. This is shown by the fact that the reactivity of HMF can only be measured in sterilised soils.
A second toxicological investigation carried out by Biodetection Systems (BDS) in Amsterdam concentrated in particular on the possible endocrine-disrupting effect of FDCA. This is a known problem that occurs with many traditional plastic constituents. However, according to Bart van der Burg, innovation director at BDS, research on human cells has revealed no indications of endocrine disruption.
FDCA registered at ECHA
FDCA had already been registered earlier with the European Chemicals Agency (ECHA) in Helsinki by Avantium in the framework of the European chemicals regulations REACH. Companies that want to put biochemical substances on the market must provide ECHA with sufficient information to register the chemical, precisely like producers of petroleum-based chemicals. This obligation stems from REACH: Registration, Evaluation and Authorisation of Chemicals. The aim is to protect humans and the environment from the risks involved in the manufacture and use of chemical substances. Manufacturers and importers of chemicals must know and identify the risks of the use and the conditions under which these chemicals can be used safely. They are obliged to register these details with the ECHA, which evaluates them and, if necessary, proposes risk mitigation measures.
Softening agent
‘Files at ECHA currently do not contain any research into the possible endocrine-disrupting effect of the registered chemical,’ explains Van der Burg. ‘It has therefore been shown not to be demonstrable for FDCA, in contrast to a chemical like bisphenol A and many phtalates. Companies use these chemicals in the manufacture of different types of plastic. There is a great deal of discussion about this because some toxicologists believe that these chemicals pose a risk due to their endocrine-disrupting effect. The European Court of Justice has even ordered the European Commission, in a legal action brought by Sweden, to also identify and list the possible endocrine-disrupting effect in the evaluation of chemicals that have already been registered at ECHA.’
A spokesperson of Corbion argues that FDCA, also in view of the favourable toxicological properties, forms an important future bio building block for the production of PEF. ‘This involves a combination of FDCA with ethylene glycol. Here the terephthalic acid in PET is replaced by FDCA, creating a biobased polymer that can replace PET,’ explains the spokesperson.
Research has also shown that PEF scores better than PET on various parameters, according to this spokesperson. ‘Products keep for longer in PEF packaging due to the better barrier properties for gases, for example oxygen, in comparison with PET. What is more, products can be pasteurised in PEF packaging.’
Enzymes
Van Straalen concludes that the production of FDCA from lignocellulose is certainly no simple matter as yet. To be sure, the material can be obtained in large quantities from the residual streams from the production of sugar cane and palm oil, as well as from all kinds of fibre-rich plant material released as waste from agriculture and forestry, such as straw, wood and reeds. At the same time, it is interwoven with lignin molecules. ‘The bottleneck of the process is getting this lignocellulose to break down,’ explains Van Straalen. ‘Currently that is being done in an environmentally unfriendly way using lyes and acids. That is why we are researching the possibility of using enzymes for this purpose.’
However, according to Van Straalen we are still a long way from an industrial application, for example as material for plastic bottles. ‘But I can imagine that Corbion wants to get started on a pilot project, just as other companies in the public-private partnership also run pilot projects in various fields.’
The research currently taking place into FDCA contains various links that will build up the entire chain towards 100 percent biobased PEF. Both industry and science play important roles in this endeavour.
