Sustainable synthesis of nanoporous carbons from agricultural waste and their application for solid-phase microextraction of chlorinated organic pollutants

Abstract

To guarantee the safety of water resources for humans, there is a high demand for the development of highly-efficient probes for solid-phase microextraction and analysis of trace organic pollutants. In this work, we greenly synthesized nanoporous carbons (NPCs) from oilseed rape straw via a facile hydrothermal treatment and potassium bicarbonate activation. Results showed that the NPCs had partly graphitic, amorphous-like structures with a high surface area (up to 1253 m² g⁻¹), large pore volume (up to 0.71 cm³ g⁻¹), high mesopore to total pore volume ratio (up to 29%) and great thermal stability (>400 °C). When the NPCs were utilized as a solid-phase microextraction fiber coating, the extraction efficiencies for chlorinated organic pollutants (COPs) were higher (1–38 times) than with a common commercial polydimethylsiloxane coating because of high surface adsorption energy, strong π–π stacking interactions and large mass transfer capacity. Using the most efficient NPC-8 coating, under optimum extraction conditions (desorption temperature, 290 °C; extraction temperature, 80 °C; extraction time, 25 min), an analysis method for trace COPs in water was developed with good linearity (0.9991–0.9998), high sensitivity (limits of detections, 0.08–0.64 ng L⁻¹), acceptable repeatability (RSDs of single fiber, 2.63–6.73%) and great reproducibility (RSDs of fiber-to-fiber, 2.22–7.12%). Finally, the NPC-8 coating was applied to a real environmental sample with satisfactory recoveries (86.66–103.27%).