A Carbon Dioxide Absorption System Driven by Water Quantity

TL;DR

This paper introduces a water-controlled CO2 capture system using nanoporous materials and carbonate ions, which absorbs or releases CO2 based on humidity levels, supported by simulations and experiments.

Contribution

It presents a novel humidity-dependent CO2 absorption/desorption system and elucidates its working mechanism through simulations and experimental validation.

Findings

CO2 absorption occurs in dry conditions; desorption occurs when wet.

Pore size, cation spacing, surface hydrophobicity, and temperature influence efficiency.

The system offers a potential approach for direct air capture and negative emissions.

Abstract

A novel system containing nanoporous materials and carbonate ions is proposed, which is capable to capture CO2 from ambient air simply by controlling the amount of water (humidity) in the system. The system absorbs CO2 from the air when the surrounding is dry, whereas desorbs CO2 when wet. A design of such a CO2 absorption/desorption system is investigated in this paper using molecular dynamics and quantum mechanics simulations, and also verified by experiments. Its working mechanism is revealed as the reduction of free energy of the carbonate ion hydrolysis with the decrease of the number of water molecules in confined nano-pores. The influences of pore size, spacing of cations, surface hydrophobicity and temperature on CO2 capture efficiency are elucidated. The study may help to design an efficient direct air capture system and contribute to the negative carbon emission.