Experimental validation of a developed waste puffed rice material for CO₂ reduction under controlled real-life indoor conditions

This study presents a comprehensive comparative evaluation of prevailing indoor air purification technologies including mechanical ventilation, activated carbon filtration, ultraviolet (UV) disinfection, ionization systems, and emerging approaches such as activated biomass, transparent filters, active living walls, and photocatalytic oxidation. The evaluation, grounded in a multi-criteria assessment framework, examines each method's performance, energy consumption, and practical feasibility within enclosed built environments. The analysis identifies significant limitations across existing strategies, particularly in the sustainability and CO₂ reduction efficacy of activated biomass systems. To bridge these gaps, a novel bio-based purification medium, developed from thermally puffed and chemically functionalized waste rice, was experimentally assessed within a controlled 1 × 1 m environmental chamber designed to replicate real-life classroom conditions. The material demonstrated a CO₂ removal efficiency exceeding 40%, achieving a reduction from 1001 ppm to 684 ppm over a four-hour exposure period. These findings substantiate the material’s potential as a low-cost, renewable, and passive purification solution, offering a scalable approach to improving indoor air quality in energy-conscious architectural settings.