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

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.

Enhanced Assembling of N-and-K-Riched Macroalgae as Carbon Adsorbent for CO2 Capture with Ni(NO3)2/KOH as Co-Catalysts.

Porous-activated carbons have drawn great attention due to their important role in CO2 capture. Ni(NO3)2/KOH, as co-catalysts under different temperatures, were studied to obtain porous graphitized carbon from Sargassum horneri feedstock. The results indicated that the properties of the porous graphitized carbon generated at 850 °C were greatly enhanced, showing a large specific surface area of 1486.38 cm3·g-1 with narrowly distributed micropores (~0.67 nm) and abundant functional groups, which endowed high CO2 uptake; moreover, the high CO2 uptake was mainly attributed to the synergistic effect of Ni(NO3)2 and KOH, both in chemical modification and pore formation. The fitted values of the four kinetic models showed that the double exponential model provided the best description of carbon adsorption, indicating both physical and chemical adsorption. It is worth noting that carbon could be reused four times in the adsorption/desorption procedure in this research with good stability. This work focuses on the high-value-added comprehensive utilization of macroalgae, which not only is important for high-performance adsorbent preparation but also has positive benefits for the development and utilization of macroalgae resources.