SOURCE: Technology x Sustainability Weekly Update

As plastic is now unavoidable in society, one of the visitor experiences that formula D_ offers to teach children about waste and recycling is the Waste Wall. It presents common household items, such as cleaning products and food items sold in various types of packaging, on a recreation of supermarket shelves. Children interact with the experience by selecting an item from the shelves and scanning its bar code using the “supermarket’s” bar-code scanner to view information about its recycling potential – or, in many cases, how much of it will actually just end up in a landfill.

Versions of the Waste Wall, with supermarket products customized to a selection commonly found in the local community, are part of a larger sustainability visitor experience for children that is installed at the Two Oceans Aquarium in Cape Town, South Africa, and the Roper Mountain Science Center in South Carolina in the USA.

In this way we’ve been helping to do our part to educate children from a young age so that they start questioning where the plastic around them is coming from – and, crucially, where it is going.

Worms To The Rescue

The enzymes in wax-worm saliva can break down polyethylene. Wax worms are the larvae of wax moths (Galleria mellonella). The worms’ effect on polyethylene was first accidentally noticed in 2017 by molecular biologist Federica Bertocchini of the Spanish National Research Council (CSIC) and further research, which was published in October 2022 in Nature Communications, went on to determine that the cause was two enzymes. The discovery is particularly notable as polyethylene is the source of PE-HD (high-density polyethylene, or “plastic #2”), which is hard to recycle in some countries, and PE-LD (low-density polyethylene, or “plastic #4”), which is almost never recycled.

[Source: Smithsonian Magazine]

Breaking Down PVC

Polyvinyl chloride (PVC, or “plastic #3”) is a very common plastic used in hospital equipment, plumbing, housing building materials, and electrical wiring. However, it is almost never recycled because it releases hydrochloric acid when heated and it contains plasticizers, which can contaminate everything else in the recycling chain and whose phthalates can cause adverse health effects in humans. (Plasticisers are substances that are added to materials such as plastic to make them softer and more flexible.)

Researchers at the University Of Michigan in the USA have now devised an electrochemical method that actually uses the plasticizers to break down the PVC and because there is no heat involved the hydrochloric acid release can be controlled and the acid can be collected for industrial reuse, while the chloride ions that the method produces have pharmaceutical and agricultural applications. Although there is still additional material left over once the process is complete that doesn’t yet have a use, the research, which was published in Nature Chemistry in November 2022, is a promising start to tackling the PVC problem.

[Source: University Of Michigan]

Sustainable Science From A Solar Source

Researchers at the University Of Cambridge in the UK have been running tests in a unique sun-powered reactor they designed with two compartments – one for greenhouse gases and one for plastic – that can be used at the same time and which results in useful compounds that are created under normal pressures and temperatures.

In the greenhouse gas compartment, their tests with a light absorber made of lead-halide perovskites and three different catalysts that were embedded in it converted CO2 into syngas (synthesis gas), which is a component of sustainable liquid fuels; formic acid; and carbon monoxide, respectively. A copper and palladium alloy catalyst embedded in the perovskites in the plastic compartment converted polyethylene terephthalate (PET, or “plastic #1”) into glycolic acid, which occurs naturally in plants and is used in skin-care products.

Their research was published in January 2023 in Nature Synthesis. They will be conducting further research to see what else will result if you change the catalysts in the compartments, with an eye to forming more complex compounds.

[Source: University Of Cambridge]

Better Bricks

CRDC (Center For Regenerative Design And Collaboration) Global, which has experimental and production plants in multiple countries, including Costa Rica, the USA, and South Africa, has developed a process that can convert any waste labeled #1 to #7 into a product it calls RESIN8, thereby theoretically making it possible to eliminate

all plastic waste from landfills. RESIN8 is an aggregate that can take the place of sand in cement for concrete and asphalt that can be used in bricks and pavers, pre-cast cement, and pour-in-place cement.

The RESIN8 plant in Cape Town, South Africa, is planned to be upscaled to a full production plant in 2023 as the aggregate has been tested to South African standards by researchers at the Department Of Civil Engineering at Stellenbosch University, as well as an independent scientist and researcher Cyril Attwell.

[Source: CRDC Global, Forbes, and Concrete Trends]