A high-performance synthetic micro-mesoporous activated carbon obtained from virgin and recycled PVDC with exceptional biobutanol separation performance

The effective recovery of biobutanol from fermentation vapor streams hinges on the development of highly selective adsorbents that can efficiently capture butanol in the presence of excess water. This paper addresses this challenge through the synthesis and characterization of tailored activated carbons. Using a high-purity polyvinylidene chloride (PVDC) precursor, in both virgin and recycled forms, a series of carbons were prepared by varying the duration of physical CO2 activation process (up to 26 h). The study establishes a clear link between these synthesis conditions and the resulting porous structure. All synthesized activated carbons displayed Type V water adsorption isotherms proving a high degree of hydrophobicity which further enhanced with increased activation time and burn-off. The nature of butanol adsorption was strongly linked to the pore structure; materials with shorter activation times and lower burn-off exhibited Type I isotherms indicative of micropore filling, while those with longer activation times and wider pores showed Type V isotherms, reflecting a cooperative adsorption mechanism. The derived activated carbons demonstrated a very high adsorption capacity for butanol vapor (0.9 g/g at 200 Pa and 40°C), significantly higher than values reported in literature for other adsorbents. Dynamic breakthrough experiments using a mixed butanol-water vapor stream validated the enhanced separation performance with a dynamic capacity very close to the equilibrium capacity. The material obtained from recycled PVDC showed excellent adsorption properties, superior to commercial benchmark materials, opening perspectives for the valorization of waste PVDC into a renewable, high grade functional porous solid.