TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The clay material contains more than 10% of amorphous material as determined by quantitative X-ray diffraction analysis of the mineral phases of the clay material. The clay material has an aluminum content, calculated as alumina (Al2O3), of less than 15 wt.%; and contains magnesium, calculated as magnesium oxide (MgO), in an amount of less than 7 wt.%. The clay material has a sediment volume in water after 1 hour of less than 15 ml/2g; and a cation exchange capacity of more than 40 meq/100. The crude biodiesel contains more than 0.2 wt.% glycerol. Preferred Method: In the method, no water washing step is performed on the crude biodiesel. The method obtains biodiesel by alcoholysis of a triglyceride. EXAMPLE - A crude biodiesel (500-800 g) obtained by alcoholysis of crude soybean oil with methanol were placed into a flask, and respective test and comparative adsorbents. The test/comparative adsorbents including silicon dioxide (SiO2) of 70.6/61.7, ferric oxide (Fe2O3) of 2.8/5.7, aluminum oxide (Al2O3) of 9.8/12, magnesium oxide (MgO) of 4.1/2.3, calcium oxide (CaO) of 1.4/4.1, potassium oxide (K2O) of 1.5/0.6, sodium oxide (Na2O) of 0.26/0.2, titanium oxide (TiO2) of 0.25/0.6, and sulfur trioxide (SO3) of 0/6.2 was used. The test adsorbent exhibiting dry sieve residue on 45 mu m of 49%, dry sieve residue on 63 mu m of 35%, apparent weight of 292 g/l, methylene blue adsorption of 106 mg/g, moisture content of 8%, pH of 7.6, cation exchange capacity of 52 meq/100 g, BET surface of 208.4 m2/g, micro-pore area of 32.1 m2/g, external surface of 176.3 m2/g, micro-pore volume of 0.016 cm3/g, cumulative pore volume for pore diameter of 1.7-300 nm of 0.825 cm3/g, average pore diameter of 16.4 nm, sediment volume of 5.5 ml/2 g was used. The comparative adsorbent exhibiting dry sieve residue on 23 mu m of 35%, apparent weight of 550 g/l, moisture content of 16%, pH of 4, cation exchange capacity of 50 meq/100 g, and sediment volume of 6 ml/2 g was used. The mixture was heated to 60degrees C in a water bath for 1 hour with stirring. The samples were filtered to remove the adsorbents and the purified biodiesel was analyzed. The test/comparative samples showed free glycerol (%) of 0.013/0.021, total glycerol (%) of 0.081/0.32, and acidity index (mg KOH/g oil) of 0.107/0.21, respectively. By addition of test adsorbents the amount of glycerol and total glycerol as well as the acidity index can be reduced in the bio-diesel sample compared to comparative adsorbent. The purification results in residual amounts for glycerol and total glycerol that were below the limits of specifications according to ASTM D 6751.