Plastic pollution is a big problem. Improper management of plastic waste can have a negative impact on the environment, wildlife and public health.

Likewise, food waste is an economic, humanitarian and environmental crisis. One third of the food produced today is wasted. Meanwhile, global food production is gradually increasing, raising concerns about food waste disposal, the best example being fruit and vegetable waste (FVW). A viable option is to establish an FVW refining platform to introduce the waste stream into the production of biodegradable biobased plastics.

This new study has developed a new strategy to address these concerns. A scientist from Singapore’s Nanyang Technological University has turned fruit and plastic waste into ultra-thin material for solar-powered water purification.

The material made from recycled fruit waste has exceptional light-to-heat conversion efficiency and can be used in equipment to purify dirty water. The scientist mainly used fruit waste such as coconut husks and orange and banana peels to make Mxenes.

Mxenes are electrically conductive compounds that have similar properties to graphene. However, unlike graphene, MXenes are made of elements other than carbon, giving them better light-to-heat conversion properties. They are stronger than steel and lightweight: the properties that allow them to replace conventional materials in industrial applications such as energy storage, optics and sensors.

This is where Asst Prof Ang comes in with his simple method of carbonizing fruit peels to make MXenes.

The prototype has an average light-to-heat conversion efficiency of 90%, which is ~30% higher than that of the commercial solar absorber. As a result, water production is ~50% higher than commercial ones.

The MXenes material can be reused because it does not come into direct contact with seawater. Only a thin layer of MXenes material is needed to go on top of the water absorber (i.e. air-laid paper).

He claimed, “The air-laid paper is like ’tissue paper,’ which is cheap. During the day, when there is sunlight, the salt from the seawater will typically crystallize on the air-laid paper. At night, however, that crystallized salt dissolves back into the sea, making it silent solar device becomes environmentally sustainable.

“The synthesis process is three times cheaper than commercial methods because the resource we use (fruit waste) is free.”

Mxene materials
MXenes materials (L) deposited on the water absorber (i.e. air-laid paper), as shown in the figure on the right (Nanyang Technological University)

prof. Ang plans to use the material in solar stills, which use sunlight to distill dirty water, energy storage and battery production.

Conventional distillation is only possible in industrialized countries due to high infrastructure and energy costs. Compared to current distillation techniques, Asst. Prof. Ang’s solar energy is still more affordable, portable and environmentally friendly.

Magazine reference:

  1. Marliyana Aizudin, Ronn Goei et al. Sustainable development of graphite-carbon nanosheets from plastic waste with efficient photothermal energy conversion for enhanced solar evaporation. Journal of Materials Chemistry A. DOI: 10.1039/D2TA02092K