New Technique Uses Plastic Waste To Sequester CO2 Emissions

Two of our biggest environmental problems are the tons of unusable plastic waste and the tons of carbon dioxide (CO2) which are released into the atmosphere in smokestack emissions. A new process is claimed to use the former to trap the latter, Ben Coxworth reported for New Atlas.

Photo Insert: Most of the pores in each particle are about 0.7 nanometers wide.

Currently being developed by a team at Rice University, the technique is a variation on an existing pyrolysis-based plastic-recycling process – pyrolysis is defined as the thermal decomposition of materials at elevated temperatures in an inert atmosphere.

The procedure begins with plastic waste being ground into a powder, after which it's mixed with potassium acetate – that's the unique part – and then heated at 600 ºC (1,112 ºF) for 45 minutes. Doing so renders the plastic powder into sorbent particles filled with nanoscale pores, which are very effective at trapping airborne carbon dioxide molecules.

Each particle can indefinitely store up 18 percent of its own weight in CO2 at room temperature. When heated to around 75 ºC (167 ºF), though, it releases the trapped carbon dioxide, which could conceivably be used in the production of products like fuels or building materials.

The sorbent particle can then be reused since approximately 90 percent of its pores are reopened as the CO2 is released. A paper on the research was recently published in the journal ACS Nano.

When the particles are initially created, a wax byproduct is also produced, which could be utilized in detergents or lubricants. While commonly used plastics such as polypropylene or high- and low-density polyethylene are typically difficult to chemically recycle, they're ideal for conversion to CO2-capturing particles.

The scientists estimate that the cost of using filters made of the sorbent to remove CO2 from flue gas streams would be about $21 a ton.

By contrast, an existing process that utilizes compounds known as amines to remove CO2 from natural gas streams reportedly costs $80 to $160 per ton. What's more, it is believed that the sorbent should last longer than the amines.

WEEKLY FEATURE : MVP Group Keeps Lights On During Pandemic