Bioplasticsinthelimelight

A journey through the curious world of bioplastics. They may cause a revolution over the next few years, in fact they probably already have, just quietly

BY STEFANO BERTACCHI

What happens when you combine sustainability, technology, and science? Often new opportunities arise, leading to developing solutions for current and future problems. But what happens when all that is combined with legislation, marketing, consumers, and the Internet? A whole lot of confusion, and often the risk of spreading disinformation to the general public who can easily fall prey to misinterpretation or fall into intentional traps when they try to understand what nobody is explaining. The best way, then, to tackle this issue (whatever this issue might be) is to be properly informed. Even more so when it is regarding scientific issues. And bioplastics represent one such case. The introduction of laws in Italy to govern biodegradable bags for fruit and vegetable produce (Italian Law no. 123/2017, introduced on January 1, 2018) triggered an apocalypse on the Internet in the early days of that year. Political accusations, economic conjecturing, people at supermarkets who put the price label on every single tomato to avoid buying bags: anything, basically. And this disconnected reaction, though exaggerated, is also attributable to those who, from lawmakers to large-scale retail trade, did not hold the consumer’s hand through the transition, even though they had known about it since August 2017, resulting in an information gap full of fragmented or incorrect information. The upside is that everyone, all of a sudden, begun to be interested in the issue of biodegradable bags and bioplastics, despite, at least at first, there being one down side. Then, as is often the case for the discussion that pops up on the Internet, the talk went away in just a few weeks. The message remains, however, that consumers are not being informed, and it is very important for this not to happen, given that this technology then ends up in the hands of the consumers themselves. Indeed, if consumers don’t know that the item they are holding goes in organic waste, it is unlikely they will throw it in the right waste bin, making all those efforts of producing a biodegradable material useless. The purpose of this article is, therefore, to lead the reader on a journey through the curious world of bioplastics, which might soon cause a revolution, one that has probably already begun in almost complete silence.

The European Bioplastics association defines bioplastic as a plastic material that is biobased, biodegradable, or that features both properties. This definition is the one lawmakers usually consider when drawing up various regulations, but it is unlikely to resolve many perplexities. Especially because it is taken for granted that the definition “biomass” and “biodegradable” leave room for interpretation. To simplify, biomass is intended to mean a renewable resource, in the majority of cases of vegetable origin, that can quickly regenerate, thanks to the free energy

Plastic is now a common material, especially in the food industry. Its extensive use in disposable items, such as water bottles, has accelerated accumulation in the environment

The biodegradability of some bioplastics facilitates the dissipation of abandoned manufactured items in the environment, reducing their impact. This should not make us want to starting throwing bags in the street!

of the sun. The process by which plants grow is possible thanks to photosynthesis, which enables plants to capture the carbon dioxide present in the atmosphere and produce new biomass. Clearly, even the origin of crude oil lies in nature since it derives from living beings, however its regeneration time is not compatible with its use, because we cannot wait millions of years for it to reform. As a result, it is a depleting resource, which is actually considered non-renewable. It is important to clarify this concept for consumers, especially when they are convinced that oil is a “non-natural” substance, as opposed to a biomass, just for this reason. In any event, we well know how problematic the use of oil as a resource is from an environmental standpoint, because its extraction and refining have an important impact on ecosystems, despite, over the years, technology drastically reducing the direct anthropic effect. Therefore, in this case, bio-based bioplastics aim to resolve the problem of using fossil resources, replacing the origin of plastic itself. Another problematic aspect of conventional petrochemical plastic, as noted, is its build-up in the environment, because of the almost non-existent biodegradability of the material. The incredible resilience of plastic is paradoxically an anathema, like a new King Midas touch that turns everything touched into gold, but that then is cursed by its own power. This is where biodegradable bioplastics come into play, which, essentially, dissipate into the environment, as if by magic. Obviously, it is not magic, because microorganisms are behind their disappearance. In combination with atmospheric agents, temperature, and humidity, they decompose this type of bioplastic, literally “eating it for their own growth.” So, translated into practical terms, if you are very distracted and leave a biodegradable bioplastic item in the park after your picnic, you’ll not want to do it again, but at least you’ll know that it will disappear much more quickly than regular plastic. Exactly how long this will take depends on a number of factors, such as the type of bioplastic, its thickness and shape, as well as environmental factors, which vary according to the location. In any event, it takes decades, which is not however long when compared to the hundreds - if not thousands - of year conventional plastic takes to decompose. But at this point, quite rightly, some readers might wonder what biocompostable means. Contrary to what many people think, is not synonymous with biodegradable. Biocompostable, in fact, is that particular object that can be disposed of in the organic fraction of municipal solid waste (OFMSW, or FORSU in Italian). This is because, subsequently, organic waste is processed in the composter: a “machine” that speeds up the biodegrading process, fully disintegrating a small coffee cup in just a few months. The concepts of biodegradability and compostability have been greatly simplified here. In reality, they vary greatly in terms of time and environmental conditions, all described in standard EN 13432. It is necessary, therefore, to be careful to distinguish the two elements, because they refer to two different destinies for plastic. In any case, these messages must be correctly handled by the consumer in order for them to know where to dispose of the material. Also because throwing away a biodegradable item in the plastic container causes problems for plastic recycling. When it comes to recycling, because bioplastics are polymers, they can be recycled, but only when they are properly collected: obviously, once they are sent to the composter, they disappear (in the literal sense of the word). Now the confusion stems from the fact that plastic derived from biomass is automatically biodegradable, while, on the other hand, plastic deriving from petrochemicals is naturally “ugly and bad” and pollutes the environment, without ever seeing a chance of redemption. If only it were that simple. In reality it is not, but, paradoxically, this makes the discussion very interesting. Unfortunately, all this creates confusion around bioplastics, especially in the consumer’s eyes. It is therefore necessary to analyse all possible combinations, unearthing properties and unique features.

As we have already seen, one of the characteristics for defining bioplastic is that it is derived from renewable biomass, whether or not it is biodegradable. In fact, contrary to what one might think, there are some bio-based bioplastics that are not biodegradable, for example, bioPET, bioPP and bioPE. You read that correctly: the acronyms stand for polyethylene terephthalate, polypropylene and polyethylene, products we are all familiar with. “Bio” used as a prefix indicates the fact that they derive from biomass and not from petrochemical processes. To synthesize the monomer of polyethylene, or ethylene, a chemical process of

PlantBottle logo and, in particular, the version presented by Coca-Cola at the Milan Expo in 2015

dehydrating the ethanol can be done. And how to obtain ethanol? Very easily, just think of a wine glass you drank from at dinner, or the beer glass from the other evening with friends: both are alcoholic and contain ethanol. The starting point for its production can be from biomass, such as grapes or barley, whose sugar components are transformed into our favourite drinks. Even in this case, the “magic” is done by invisible conjurers, namely microorganisms: in particular yeast is able to ferment the above-mentioned sugars to produce ethanol, which is why it is called bioethanol. In fact, it is identical to ethanol obtained by petrochemical processes, but the prefix reminds us that it comes from biomass. Bioethanol is used as biofuel for socalled “flexi fuel” motors to replace petrol, but in this case, it can also be used as the initial base for plastic. It is mandatory, therefore, to thank yeast not only for beer, but also for other chemical substances that are not limited to polyethylene, because propylene and, as a result, bioPP, can be obtained from ethylene (at this point bioethylene). Similarly, as you can imagine, you can also “put your hands on” PET, as ethylene is one of the two monomers it is made from. This is how the PlantBottle brand (brand registered by The Coca-Cola Company) came about, a material made up of bioPET and

The author Stefano Bertacchi

PhD in Industrial biotechnology and post-doctoral researcher of the University of Milano Bicocca, Stefano Bertacchi develops bioprocesses based on residual biomasses, using natural or engineered microorganisms to synthesize molecules for industry, such as bioplastics. Science communicator, speaker and author of the books “50 grandi idee. Biotecnologie” (Dedalo, 2021), “Piccoli geni - Alla scoperta dei microrganismi” and “Geneticamente modificati - Viaggio nel mondo delle biotecnologie” (Hoepli, 2021 and 2017). used for some products by big global names, such as Coca-Cola and Ford. Currently, 30% of the most common bioPET is made up of bio-based material. Why 30%? Because, no surprise, it is the ethylene which we talked about before. Its “polymer companion” or terephthalic acid, is more complicated to obtain from renewable sources because of the presence of the inconvenient aromatic ring, which in nature is a bit of a double-bladed sword. One of the ways to synthesize it from renewable sources is to start with isobutanol, which in turn can be obtained by fermenting the sugars, similarly to ethanol. In this case we obtain bioPET that is 100% derived from renewable sources, and this is certainly a goal of the companies involved in the project. The first PlantBottle 100% was introduced during Expo 2015, in Milan. However, despite deriving from biomass, this bioPET is still a PET and its identification code remains 1; as a result, it can be thrown into plastic bins. This is despite being to all intents and purposes a bioplastic. It is impossible to distinguish between PET and bioPET, because it is literally the same molecule. The only way to do it is to analyse and date the atoms, which will determine if they derive from freshly synthesized biomass or from the organisms that died millions of years ago. For this reason, bioPET, bioPE (code 2 or 4), bioPP (code 5) can be recycled, but are not biodegradable. And here is where the confusion lies for the consumer who, thinking about “green” plastic derived from plants, automatically associates this element with being biodegradable. And they risk throwing a bottle in the organic waste bin that will not be broken down in the composter.

This Milanese saying basically means “be careful”, and it is what must be done with bioplastics. The warning is for everyone, not just the consumer but also the producer, who does need to rethink their marketing to underline the virtuous use of renewable biomasses in place of oil, but also to provide guidance on the correct disposal of the product post consumption. Non-biodegradable bioplastics like bioPET, bioPP and bioPE are indistinguishable to insiders, so it is no surprise that consumers cannot tell the difference. In any event, these bioplastics have the purpose of resolving one of the two problems of petrochemical plastics, namely the relative use of fossil resources. This is very important both for the environmental reasons mentioned as well as because of the socio-economic instability of oil. In addition to this, oil is a resource that is not distributed in a uniform manner, making it hard to source on a global scale. Biomasses, on the other hand, are available in a more or less uniform manner on all continents, facilitating local production of plastic, where necessary. The problem of final disposal is, however, unresolved. Despite this, we have filled the world up so much with PET that some microorganisms have become very quick at disposing this polymer, providing a valid starting point for developing new disposal systems. But this argument will be addressed in more detail in a future article. For now, we are only at the first act of the bioplastics show, appearing on the market and in the lives of people. In the second act, we will address biodegradable bioplastics, deriving from biomasses and/or oil. As is often the case, to fully understand the value of what we are about to see, it is best to first get to really know the leading actors. www.macplas.it