Green Science Alliance Made Quantum Dot from Plastic Wastes

KAWANISHI-CITY, Japan, Nov. 11, 2025 /PRNewswire/ -- Green Science Alliance is the Green Tech Startup company to develop cutting-edge materials and technologies for sustainable, carbon neutral society in energy and environmentally friendly field. 

This time, Dr. Ryohei Mori at Green Science Alliance has successfully synthesized carbon quantum dots from plastic wastes.

Quantum dots are extremely tiny man-made nanoparticles typically between 10 to 10000 atoms or molecules (1 to 9 nanometers) in diameter, which is smaller than 1/10000th the width of a human hair.  They are sometimes called artificial atoms or molecules.  At this size range, the energy levels of electrons are no longer continuous and are separated due to the physical phenomenon known as the quantum confinement effect. The electronic characteristics of quantum dots are determined by quantum confinement effect depending on their chemical composition, size, shape so that the wavelength of emission light depends on those characteristics.  The unique properties of quantum dot can be utilized for solar cell, display, bio imaging, photonic crystal, laser, LED, artificial photosynthesis and quantum dot computer etc…

Environmental problems such as global warming, climate change, water pollution and scarcity and deforestation etc… are serious issues caused by population growth. In particular, plastic pollution is becoming a devastating level that destroys ecosystems.

Approximately 8.3 billion tons of plastic produced in the world between 1950 and 2015, about 6.3 billion tons have been disposed as waste.  Out of these plastic waste amount, approximately 79% (about 4.9 billion tons) is landfilled, and 12% is incinerated.  Therefore, only 9% of plastics have been recycled.  In 2019, the total amount of plastic waste generated globally was 353 million tons. It is predicted that by 2050, the total weight of plastic in the ocean will exceed the weight of fish.

Meanwhile, the impact of extremely small plastic pieces referred to as microplastics and nanoplastics, is enormous. Microplastics and nanoplastics have already been found everywhere on Earth, from the summit of mount Everest to the bottom of the Mariana Trench. Nanoplastics are already entering into our bodies through our breathing air and the food we eat, and thus, there are concerns about potential adverse health effects.  Recent research reports that these nanoplastics could increase the risk of heart attack and stroke, cause inflammatory reactions in the digestive system, and have negative effects on the immune response.  Thus, it is important to promote using biodegradable plastics or recycling plastics.

The type of plastic recycling can be largely divided into 3 categories.

1. Material Recycling: Waste plastics are melted by high temperature and re-made into plastic (resin) pellets as raw materials.  Container, bench, pallet, building materials, sheet are made by this procedure for example. 
   
   
2. Chemical Recycling: A method of recycling waste plastic into chemical raw materials by chemical decomposition. Plastic waste are decomposed into gas, oil and can be utilized as raw materials for hydrogen, methanol, resin monomer, reducing agent etc…
   
   
3. Thermal Recycling: Utilizing generated thermal energy when waste plastics are incinerated. They can be used as power generation, heat source, hot water production etc…  Remained solid residue after incineration can be used as raw material for cement, solid fuel (RPF, RDF) etc…

Above are the major 3 process of waste plastic recycling although 90% of waste plastics are either landfilled or incinerated as described above. 

However, plastic recycling costs money and especially for material recycling, it would be difficult to maintain the recycled plastic quality and properties. If plastic wastes contain dirt, impurities or mixed plastics, then it would be difficult to recover as recycled plastics. For those reasons, the ratio of plastic recycling remains lower than 10 % compared to all disposed plastic waste in the world.  

As such, it will be a great achievement if one could develop new method to convert plastic wastes into something valuable and useful. In this regard, Dr. Ryohei Mori made quantum dots from plastic wastes. Prepared quantum dots are a kind of carbon quantum dots and can be applied to sensor, bio-imaging, catalyst, LED, for energy industry and for agriculture etc…owing to its unique optical properties and physicochemical characteristics.  He will continue research of application of this plastic wastes derived carbon quantum dots.

Contact:
Ryohei Mori
81-90-85282305
[email protected]

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SOURCE Green Science Alliance Co., Ltd.