Facile synthesis of hierarchical porous carbon from crude biomass for high-performance solid-phase microextraction

Porous materials have great prospective applications for solid-phase microextraction (SPME) technology because of their large specific surface area and pore volume. In this study, a hierarchical porous carbon (HPC) was synthesized by simple hydrothermal reaction and potassium hydroxide (KOH) activation of crude biomass and found to be an efficient adsorbent for SPME of organic pollutants. Results show that the as-prepared HPC has a partly graphitic amorphous-like structure with ultrahigh specific surface area (2551 m²/g), high pore volume (1.53 cm³/g), good pore size distribution (PSD) (mesopore/micropore ratio of 68%), and great thermal stability (>450 °C). When we utilized it as SPME fiber coating, the extraction capacities for chlorobenzenes (CBs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and phthalates (PAEs) were, respectively, 1.13-39.46, 2.40-7.78, 1.34-36.02, and 1.50-1.83 times higher than those of a commercial polydimethylsiloxane (PDMS) fiber. Under the optimized extraction conditions, an analytical method for CBs with low detection limits (0.01-0.24 ng/L), good repeatability (1.00%-4.93% for intra-day, 1.11%-6.94% for inter-day), and great reproducibility (1.48%-8.91%, n = 3) was developed. Moreover, we evaluated the practicality of the developed method for environmental water sample and obtained satisfactory recoveries (86.21%-104.34%). The findings provide a novel and promising HPC from crude biomass using a low-cost and facile synthetic route for SPME applications.