Application of sorbents in DAC technology for urbanCO۲ emission reduction; a review

This review explores how Direct Air Capture (DAC) technology can reduce CO₂ emissions in urbanareas, focusing on the sorbents that enable this process. DAC operates similarly to plants'photosynthesis by capturing CO₂ from the atmosphere. This technology is especially beneficial incities, where emissions are significantly high due to vehicles and industrial activities. For DAC to beeffective and scalable, it is crucial to identify suitable sorbents that can efficiently trap and concentrateCO₂.The review draws from various scientific sources to examine liquid and solid sorbents, includingalkaline solutions, amine-based solvents, metal complexes, activated carbon, zeolites, and metalorganicframeworks (MOFs). Each sorbent's strengths and limitations are discussed to understand itseffectiveness in DAC applications.Liquid sorbents, such as those based on alkaline solutions and amines, capture CO₂ well but havedrawbacks like high energy requirements for regeneration, corrosion issues, and potentialenvironmental impacts. In contrast, solid sorbents, including activated carbon and MOFs, tend to bemore energy-efficient during regeneration and demonstrate strong CO₂ trapping capabilities, althoughthey may be sensitive to moisture. Recent advances in sorbent design, including surface modificationsand composite materials, hold promise for further enhancing performance.Conclusively, DAC shows significant potential for lowering CO₂ levels in cities; however, technicaland financial challenges must be addressed for large-scale implementation. Continued research isessential, and with further innovation, DAC could become a vital tool in combating climate change.