This study examines corn stalk biochar (CSB)-enhanced mortar as an innovative material for carbon capture and CO
2 sequestration. CSB, a renewable agricultural byproduct, was incorporated into cement mortar at varying concentrations (2.5% to 75%), and its effects on the mortar’s physicochemical properties,
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This study examines corn stalk biochar (CSB)-enhanced mortar as an innovative material for carbon capture and CO
2 sequestration. CSB, a renewable agricultural byproduct, was incorporated into cement mortar at varying concentrations (2.5% to 75%), and its effects on the mortar’s physicochemical properties, its ability to support algal growth, and the CO
2 absorption capacity of the algae were analyzed. Characterization of CSB showed a high carbon content (62.3%), significant porosity, and a large surface area (680.3 m
2 g
−1), making it ideal for gas capture. At low concentrations (2.5%), CSB slightly improved the mortar’s compressive strength and density. However, higher CSB levels (5% to 75%) led to significant reductions (
p < 0.05) in strength and density, while water absorption increased. CO
2 sequestration monitored from algal growth studies revealed that both
Chlorella sp. (TISTR 8262) and
Scenedesmus sp. (TISTR 9384) thrived on CSB-enhanced mortars. At a 75% CSB concentration,
Scenedesmus sp. achieved a 24.2-fold increase in biomass by day 12, outperforming
Chlorella sp., which showed a 26.6-fold increase. CO
2 absorption also improved with biochar. Mortars with 75% CSB achieved an 86% CO
2 absorption ratio without algae, while adding algae boosted this to nearly 100%, highlighting the synergistic effect of biochar and algal photosynthesis. Higher CSB levels accelerated CO
2 absorption stabilization, reaching saturation by day 8 at 75% CSB.
Scenedesmus sp. showed slightly higher CO
2 absorption efficiency than
Chlorella sp., reaching peak absorption earlier and maintaining greater efficiency. Higher CSB concentrations accelerated CO
2 absorption, indicating that biochar–mortar mixtures, particularly when combined with algae, provide a promising solution for enhancing carbon capture and sequestration in green infrastructure.
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