Ali NabaviOMAR ABDULHAMID ALI FALLATAH2022-05-302022-05-30https://drepo.sdl.edu.sa/handle/20.500.14154/52672A continuous release of CO2 reduces air quality in enclosed environments such as spacecraft and International Space Station atmospheres. Poor air quality leads to health issues; therefore, CO2 removal systems are used. This thesis presents a critical review of the current carbon dioxide removal systems used to remove the CO2 created by the metabolic processes of the crew. The CO2 removal systems for space applications use sorbent materials to absorb CO2; some of these sorbents will be discussed here. Sorbent materials are classified into two groups: chemisorption and physisorption. Each group has its carbon capture process for space applications, including LiOH carbon dioxide scrubber unit, regenerable CO2 removal system (RCRS), and four-bed molecular sieve (4BMS). The advantages, disadvantages, and challenges of each unit are also discussed. Moreover, how to achieve a reliable and sustainable life support system that can capture the CO2 and utilise it to get water and oxygen as the final products is presented. The 4BMS with a closed loop is the ideal system for CO2 removal with a grade 544 (13X) zeolite sorbent.en