BACKGROUND: Glycerol (Gly) a by-product from biodiesel production was impregnated onto the surface of expanded vermiculite (EV) and reacted to produce a highly efficient absorbent to remove oils spilt on water. RESULTS: Expanded vermiculite was impregnated with glycerol at EV/Gly ratios of 1/1, 1/2, 1/3 and 1/4, and treated at 380, 480, 580 or 700 degrees C. Electrospray ionization mass spectroscopy, thermogravimetry, BET surface area, Hg porosimetry and Raman analyses indicated that residual NaOH from the biodiesel process catalyzed the polymerization of glycerol. At higher temperatures the polymer decomposed to form a carbon layer covering the EV surface. These materials were investigated for the removal of three different oils, i.e. diesel, soybean and engine oil spilt on water. CONCLUSION: This work showed that glycerol from biodiesel production can be used directly to produce a highly efficient absorbent to remediate oil spill accidents. The results obtained showed a remarkable increase on oil removal efficiency with a strong decrease on water absorption. (C) 2009 Society of Chemical Industry