Design and synthesis of bio-medical carbon materials from biomass: impact of lignocellulose on carbon structure

Abstract

Turning farm and forestry wastes into high-performance activated carbons first demands a clear link between what the biomass is made of and how it responds to heat. In this study, we analysed nine common residues whose polysaccharide-to-lignin ratios span almost one order of magnitude, pyrolysed them at 450, 700, and 950 °C under N₂, and, for the most lignin-rich (coconut shell) and the most polysaccharide-rich (corn cob) samples, added a CO₂ activation step. A U-shaped trend emerged at pyrolysis temperatures of 450 and 700 °C, where both the lignin-rich and the polysaccharide-rich ends of the series produced more surface area than the mid-range materials. However, this relationship inverted at 950 °C, with the lignin-rich coconut shell char exhibiting a much higher surface area than its polysaccharide-rich counterparts. After pyrolysis at 950 °C, coconut-shell char reached 554 m² g⁻¹, whereas corn-cob char levelled off at 136 m² g⁻¹. Introducing CO₂ activation magnified this gap: the specific BET surface area (SBET) jumped to 1451 m² g⁻¹ for coconut shell but rose only to 218 m² g⁻¹ for corn cob. The data show that low polysaccharide-to-lignin ratios favour gradual aromatisation and tight micropore retention, while high ratios cause early devolatilisation and a fragile skeleton that coarsens during gasification. Together, these insights yield a practical map for matching feedstock, temperature, and desired surface area: lignin-rich woods can deliver ultramicroporous carbons (>1400 m² g⁻¹) suited to biomedical adsorption and supercapacitors, whereas polysaccharide-rich herbs offer moderate areas with more oxygenated sites for catalytic supports, streamlining the path from raw biomass to application-ready activated carbons.

Date of Award	15 Jul 2026
Original language	English
Awarding Institution	University of Nottingham
Supervisor	Cheng Heng Pang (Supervisor), Edward Lester (Supervisor), Qingxin Zhang (Supervisor) & Chung Lim Law (Supervisor)