Kapok Fibre Oil Absorption and Environmental Applications

Kapok fibre's hollow tubular structure (lumen diameter 15–30 µm, wall thickness 1–2 µm, aspect ratio 200–500) and hydrophobic wax surface (contact angle 130–140°) enable oil absorption capacity of 30–40 g oil/g fibre for diesel and crude oil, making it the highest natural fibre oil absorbent known. Oil absorption rate of 95% in 60 seconds versus 85% for polypropylene nonwoven at equivalent basis weight. Oleophilic-hydrophobic selectivity enables oil-water separation with 90–96% oil removal efficiency from oil-water mixtures at 1:10 oil-water ratio (ASTM F726). After oil absorption, kapok is squeezed and reused 10–20 times retaining >80% capacity. Pyrolysis activation at 400–600°C increases surface area from 2 to 400–800 m²/g (BET), enhancing heavy metal adsorption (Pb²⁺, Cu²⁺) at 150–300 mg/g capacity for water treatment applications.