Turn Waste Golden Tide into Treasure: Bio-Adsorbent Synthesis for CO₂ Capture with K₂FeO₄ as Catalytic Oxidative...

Converting Sargassum horneri (SH)-a harmful marine stranding that can cause golden tide-to highly porous bio-adsorbent material (via one-step catalytic oxidative pyrolysis with K₂FeO₄) can be a strategically useful method for obtaining low-cost materials suitable for CO₂ capture. In this manuscript, the behavior of different mass ratios of K₂FeO₄/SH precursor acting on the surface physicochemical properties of carbon materials are reported. The results suggest that specific surface area and total pore volume first increased to the mass ratio of K₂FeO₄/carbon precursor, then decreased. Among the samples prepared, the highest specific surface area was obtained with a K₂FeO₄/SH precursor ratio of 1:4 (25%-ASHC), and the CO₂ adsorption performance was significantly increased and faster compared with the original biochar. The fitted values of the three kinetic models showed that the double exponential model provided the best description of carbon adsorption, indicating both physical and chemical adsorption; 25%-ASHC also exhibited excellent cyclic stability. The improved CO₂ adsorption performance observed after K₂FeO₄ activation is mainly due to the increase in material porosity, specific surface area, and the enrichment of nitrogen and oxygen functional groups.