Gas treatment method, and gas treatment device

A gas treatment method comprising:

• an absorption step of bringing a gas to be treated, which contains carbon dioxide and a sulfur compound, into contact with an absorption liquid to be phase-separated by not only carbon dioxide absorption but also sulfur compound absorption, to cause the absorption liquid to absorb the carbon dioxide and the sulfur compound, wherein the absorption liquid is phase-separated into a first phase portion and a second phase portion by absorption of the carbon dioxide and the sulfur compound, and a content rate of the carbon dioxide and the sulfur compound in the first phase portion is higher than a content rate of the carbon dioxide and the sulfur compound in the second phase portion;
• a first release step of heating the first and second phase portions to a temperature equal to or higher than a temperature at which the carbon dioxide absorbed by the first and second phase portions is released from the first and second phase portions and lower than a temperature at which the sulfur compound absorbed by the first and second phase portions is released from the first and second phase portions, to release the carbon dioxide from the first and second phase portions;
• and
• a second release step of heating the first phase portion after the first release step to a temperature equal to or higher than a temperature at which the sulfur compound absorbed by the first phase portion is released from the first phase portion after releasing the carbon dioxide from the first phase portion in the first release step, to release the sulfur compound from the first phase portion.