LOW-ENERGY CARBON CAPTURE WITH ZEOLITE MOLECULAR SIEVES: A STUDY OF CASCADE FILTER EFFICIENCY IN CCS PROTOTYPES

• Cascade ZMS adsorption achieved an average CO₂ capture efficiency of 88% • Water-facilitated CO₂ capture enhanced adsorption under ambient conditions • The CCS prototype operated at low energy consumption of 129.4 kJ/mol CO₂ • Cascade configuration enabled stable stage-wise CO₂ concentration reduction Electricity demand remains a key barrier to scalable carbon capture and storage (CCS), while energy reporting for adsorption-based prototypes is often inconsistent across operating conditions. This study targets decentralized emission control in built environments (e.g., small engines and local exhaust sources) by evaluating a low-energy, open-air CCS prototype based on a four-stage cascade Zeolite Molecular Sieve (ZMS) 5A filter (116 g per stage; 464 g total) coupled with water-facilitated CO₂ capture. Exhaust from a 125 cc gasoline engine (50,000 ppm CO₂ inlet) was processed using a 120 W blower. The water-drop flow was optimized from 700 to 1,900 mL/min, yielding a maximum capture efficiency of 96.6% at 1,416 mL/min. Under this operating condition, five repeated trials reduced CO₂ from 50,000 ppm to 5,924 ppm, corresponding to 44,076 ppm captured and an average overall capture efficiency of 88.2%. The average electrical energy consumption was 64.88 Wh over a 0.53 h measurement window, resulting in an Energy Consumption Index (ECI) of 1.47 mWh/ppm. These results provide a transparent concentration-based energy metric for comparing ZMS cascade CCS performance and support practical development of modular low-energy mitigation technologies for the built environment.