Plastic waste and rising levels of carbon dioxide (CO2) in the atmosphere are among the top environmental concerns facing humanity today. Therefore there is a demand for economical alternatives for CO2 capture.
A team from Rice University has developed a new chemical technique that converts hard-to-treat plastic waste into an effective carbon dioxide absorber (CO2) for industry. The technique is a variation of the current plastic recycling process based on pyrolysis.
To make the material, the researchers ground plastic waste into a powder, mixed it with potassium acetate and heated it to 600 degrees Celsius (1,112 degrees Fahrenheit) for 45 minutes to optimize the pores, which most are about 0.7 nanometers wide. . Higher temperatures led to larger pores. Heating plastic waste in the presence of potassium acetate produced particles with nanoscale pores that trap carbon dioxide molecules.
These porous particles can retain up to 18% of their own weight in CO2 at room temperature. Heating it to about 75 degrees Celsius (167 degrees Fahrenheit) releases carbon dioxide trapped in the pores, regenerating about 90% of the material’s bond sites. The sorbent can then be reused.
The captured CO2 could eventually be used in the production of products such as fuels or building materials. The process also produces a wax by-product which can be recycled into detergents or lubricantsthe researchers said.
While typical chemical recycling does not work for polymer wastes with low fixed carbon content to generate a CO2 sorbent, including high and low density polyethylene and polypropylene, the main components of municipal waste, these plastics work particularly well. to capture CO2 when treated with potassium. acetate.
“Point sources of CO2 emissions, such as power plant exhaust stacks, can be fitted with this material derived from plastic waste to remove huge amounts of CO2 that would normally be released into the atmosphere,” said said James Tour. “It’s a great way to tackle one problem, plastic waste, and another problem, CO2 emissions.”