Hemp Hurd Activated Carbon Production

Hemp hurd activated carbon is produced by chemical activation with KOH (impregnation ratio KOH:hurd 2:1–4:1 by weight, carbonisation at 700–850°C under N₂, 60–90 min) or physical activation with CO₂ (850–900°C, 60–120 min activation). BET surface area of 800–2,200 m²/g, total pore volume 0.4–1.2 cm³/g, and micropore fraction 60–80% (pore diameter <2 nm) produce high-performance adsorbents for supercapacitor electrodes (specific capacitance 150–350 F/g at 1 M H₂SO₄), heavy metal removal (Pb²⁺ adsorption capacity 150–280 mg/g, Langmuir isotherm), and CO₂ capture (adsorption capacity 3.5–5.5 mmol/g at 0°C, 1 bar). Hemp hurd activated carbon specific capacitance of 300–350 F/g (optimised KOH activation) surpasses commercial coconut shell activated carbon (150–220 F/g) for supercapacitor applications. Production cost of €2–5/kg hemp activated carbon is competitive with coconut shell carbon (€3–6/kg) at equivalent performance. Growing demand for bio-based electrode materials in energy storage is driving interest in hemp hurd-derived carbon as a high-value by-product valorisation pathway.