It’s still greener

The chemical industry must become more environmentally friendly. But not every strategy is sustainable in the long term. Which approaches are useful.

The undesirable side effects of material prosperity are seldom as obvious as the colorful plastic mix of bottles, flip-flops and fishing nets that blemishes some holiday beaches. Most of the potentially harmful chemicals in the environment are invisible to the naked eye: flame retardants, for example, biocides, pesticides, medicines and long-lasting fluorochemicals that can be found in coated pans, jackets and baking paper and, as the Federal Environment Agency recently reported, in alarmingly high doses have been detected in the blood of children. Again and again, chemists find problematic substances where they don’t belong.

At some point Klaus Kümmerer from Leuphana University Lüneburg had enough of such finds. “I just didn’t feel like measuring the five thousandth pollutant in the six hundredth sampled area,” says the scientist. For 15 years he has been researching how chemistry can be made more sustainable from the ground up. Together with his team, for example, he chemically converted a heart drug, a beta blocker and an antibiotic so that they can be more easily broken down by microbes in the environment. Similar to how chemists once defused surfactants from detergents that had produced meter-high mountains of foam on the rivers in the early 1960s.

“Benign by Design” is the name of the concept of chemically assembling substances in such a way that they cause as little damage as possible to the environment. It is one of the twelve guiding principles of so-called green chemistry, which were developed 22 years ago by the US chemists Paul Anastas and John Warner. “Green” are also products and manufacturing processes that produce as little waste as possible, that use little energy and resources, or those from renewable sources. There are countless examples of the success of the concept today, says Julie Zimmerman from Yale University, USA, who works with Anastas. They range from batteries for electric cars to biofuels and gentle production methods for cancer drugs that generate little waste.

Planet plastic

“One of the biggest challenges is getting away from the concept of waste and seeing every ‘waste’ as a resource,” says Zimmerman. At the beginning of the year , her team reported in the journal Science on two examples that are already being implemented industrially. The wood waste material lignin from the paper industry is used, among other things, as a raw material for vanilla flavoring, and chemical building blocks for foams made of polyurethane can be obtained from the greenhouse gas carbon dioxide.

From Kümmerer’s point of view, the main ideas behind green chemistry are correct, but they often fall short. “They do not consider the entire material and product flows and how they could be reduced,” he criticizes. Metals that are increasingly in demand for digitization, for wind turbines and solar cells, or phosphorus for fertilizers, for example, are simply finite and thus resources that have to be managed well. “The first thing you should ask yourself about every chemical and every product is: Do I even need it?” He is convinced.

Fungal resistant wood could make fungicides superfluous in facade paints

For some functions there are definitely more sustainable, non-chemical alternatives. To protect wooden structures, for example, a roof overhang or fungus-resistant wood could make the use of fungicides in facade paints superfluous. “Only when it is clear that a chemical compound is needed does the question of how it can be produced most sustainably,” emphasizes the chemist. This also includes observing ethical and social criteria, such as the origin of the resources and the conditions under which they are obtained.

The example of biodiesel shows how much damage a narrowed view can be. Part of the fuel is obtained from vegetable oil instead of crude oil, i.e. from renewable raw materials. But rainforests have already been cleared and moors drained for the oils, which will continue to release carbon dioxide for centuries. Fields are also blocked for food production. “That does more harm than good,” said the Nobel Laureate in Chemistry, Hartmut Michel, recently at the virtual Lindau Nobel Laureate Meeting. In addition, the efficiency of photosynthesis, with which plants produce biomass from light and carbon dioxide, is extremely low at around one percent. It is more efficient to generate hydrogen with solar power,

As far as the circular economy is concerned, it is also worth taking a look at the details. ” Recycling is always associated with material losses, energy consumption and other waste materials,” says Kümmerer. The more substances there are in a material, the more difficult it will be to separate them again. Many plastics, for example, still contain dyes, flame retardants and plasticizers.

Innovative composite materials that are supposed to make cars lighter are also problematic. “They may help to save carbon dioxide, but in 20 years you will be there and have to see how you can recycle it,” said Kümmerer. The same problem arises today with innovations from the past, such as electrical appliances, wind turbines and solar cells. “Products and materials have to be planned much more so that they can be recycled,” demands the chemist. The simpler they are set up, the better.

Every innovation should immediately be critically questioned: Do you really need it?

Some substances cannot be put into the cycle, such as shampoo, cleaning agents or medication. Because sewage treatment plants often cannot collect them and around 80 percent of the world’s wastewater cannot be cleaned anyway, they should be designed in such a way that they decompose completely as quickly as possible.

For researchers like Zimmerman and Kümmerer, there is no question that government pressure and financial incentives are required to make the chemical industry more sustainable. New business models can also help. For example, so-called chemicals leasing, which has been promoted for several years by the United Nations Industry Department UNIDO together with Switzerland, Austria and Germany. Manufacturers or importers do not sell chemicals, but a service that also includes advice and the return of chemicals.

One example is car manufacturers who pay paint producers for the painted sheet metal area instead of the paint itself. “Then there is an incentive to achieve good quality with as little paint as possible,” explains Kümmerer. In hospitals, manufacturers of disinfectants can be paid for advice on the necessary hygiene standard instead of the chemicals. His team successfully tested this in a clinic in Worms, says Kümmerer. About half of the disinfectants could be saved.

Last but not least, the topic of sustainable chemistry is a compulsory part of the training. But this is still more the exception than the rule, also in Germany. Since March of this year, Leuphana University has been offering a part-time master’s degree in sustainable chemistry under Kümmerer’s leadership. The researcher asks his students to critically question every innovative product idea: What function should the product fulfill? What are the consequences if I produce 100,000 tons of it? Where does the material come from? How much do you lose And all of this beyond the first life cycle, says the scientist: “We need this kind of thinking.”

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