Advances in Leaching Agents for Indirect CO₂ Mineralization

Area of Science:

• Materials Science and Engineering
• Environmental Science and Technology
• Chemical Engineering

Background:

• Industrial solid waste contains metals reactive with CO2, offering potential for CO2 mineralization.
• CO2 mineralization is a key Carbon Capture, Utilization, and Storage (CCUS) technology for permanent CO2 storage and waste valorization.
• Indirect mineralization selectively leaches calcium (Ca2+) from solid waste for conversion into valuable calcium carbonate (CaCO3).

Purpose of the Study:

• To systematically review the progress of indirect CO2 mineralization, focusing on leaching agents.
• To analyze the mechanisms, advantages, and limitations of different leaching agent categories.
• To identify challenges and future research directions for industrial implementation.

Main Methods:

• Categorization of leaching agents into acid-base, ammonium salt, and multifunctional organic types.
• Review of mechanisms for Ca2+ leaching and CO2 mineralization for each agent type.
• Analysis of factors affecting leaching efficiency, selectivity, reagent recovery, and CaCO3 properties.

Main Results:

• Acid-base agents are efficient but corrosive and poorly recyclable.
• Ammonium salt agents are selective and recyclable but cause ammonia emission and reagent loss.
• Multifunctional organic agents (amino acids, chelating agents) show advantages in efficiency, stability, and crystal control, but face high costs and safety concerns.

Conclusions:

• Leaching agent performance is critical for the industrialization of indirect CO2 mineralization.
• Multifunctional organic agents offer significant potential but require cost reduction and enhanced environmental safety evaluation.
• Future research should focus on optimizing organic agent design and safety assessments to enable widespread industrial application.