From plastic waste and clay to useful materials
Advanced materials often start with purified laboratory chemicals, which can be expensive. But some of the ingredients we need can come from cheaper sources, including materials we already throw away.
A second life for plastic
PET is the plastic used in many drinks bottles. It can be broken down into terephthalic acid, a building block for some metal-organic frameworks (MOFs), which are crystals full of tiny pores.
We have used recycled PET from plastic waste to make light-activated materials for cleaning water. One degraded 95% and 99% of two industrial dyes after four hours, with only a small change in performance after four consecutive tests. Another was designed to break down the antibiotic tetracycline.
Catalysts from clay
Halloysite is a natural clay containing silicon and aluminium. These are also the elements needed for porous supports such as Al-SBA-15, whose regular channels help molecules to reach a catalyst.
We used halloysite as the source of silica and aluminium to make a silver-based catalyst for removing sulfur from fuel. Under sunlight at 70 °C, it removed 98.66% of a stubborn sulfur compound called dibenzothiophene from a model fuel.
Why it matters
Using waste and abundant natural materials could lower costs and make better use of resources, while also making use of plastic that might otherwise be discarded. These are laboratory results. Real waste varies from batch to batch, so proving consistent quality at larger scale is an important next step.
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