The new sorbents have three times the capacity to absorb carbon dioxide from the air than existing ones. The sorbent also converts carbon dioxide into sodium bicarbonate, or baking soda, which can be safely retained in the oceans when exposed to seawater. According to the International Energy Agency, 18 plants that extract carbon dioxide directly from the air are currently operating in Canada, Europe and the United States (IEA). In these pilot scale plants, carbon dioxide is captured using amine-based liquids or solids. After the materials are heated to release the carbon dioxide for use or storage, the sorbent is made ready for reuse.
Carbon Dioxide Capture Techniques
However, with today's technology, a ton of CO₂ can be captured for only a few hundred dollars. According to the IEA, costs must come down before direct air capture (DAC) can be used widely enough to help reduce carbon emissions worldwide to zero by 2050.
Increasing the ability of a sorbent to absorb CO₂ at a concentration of 400 parts per million in air is one technique for doing this. Arup K. SenGupta, an environmental engineer at Lehigh University, and his team passed a copper chloride solution through resin beads containing polyamine groups to create a high-capacity sorbent.
The nitrogen atoms in the amines form a bond with the copper ions, turning the beads blue. The copper-modified beads captured about 5 moles of CO₂/kg, three times more than untreated beads and most other known solid sorbents when atmospheric air was pushed through a column filled with them. CO₂ and water vapor in the air react to form bicarbonates that bind to the copper-nitrogen complex. This reaction is triggered by positively charged copper ions.
The scientists then passed the seawater through the colon. Sodium bicarbonate, which can be released into the sea, is formed when copper ions replace bicarbonate ions with chloride in salt found in salt water. According to SenGupta, the oceans could serve as an important carbon dioxide sink.
According to him, the higher capacity of the new sorbent should result in lower DAC costs. He envisions onshore or offshore facilities where air and water from the sea flow through columns filled with sorbent. The water containing the baking soda is then discharged into the ocean. If we achieve a large capacity, it will cost less than $100 per tonne of CO₂. For direct air capture to be used globally, we need a technique that can extend to underdeveloped or poor countries.
David Keith, a Harvard University physicist and creator of the DAC initiative Carbon Engineering, argues that the material's ability to load carbon is remarkable. But if you want to keep the cost down, you need to speed up how fast the material absorbs carbon dioxide. “Fast kinetics are required for effective air capture, otherwise the cost of the air contact system will increase,” he says.
Source: cen.acs.org/environment
Günceleme: 21/03/2023 12:49