Preparation of activated charcoal from Acrocomia aculeata for purification of pretreated crude glycerol

Activated charcoal was prepared from Acrocomia aculeata (macaúba) endocarp by ZnCl 2 activation and then used for the adsorptive purification of pretreated crude glycerol (CG) containing pigments, such as β-carotene. The pretreatment of glycerol involved filtration of the K 3 PO 4 formed by the addition of H 3 PO 4 to the crude glycerol containing KOH. A mixture of 1.38:1 w/w of ZnCl 2 : Acrocomia aculeata pulp was heated at 120 °C with stirring for 24 h. The mixture was activated by heating at 600 °C for 3 h. The activated charcoal was cooled to 25 °C, washed with a 1:1 mixture of methanol and water (100 mL) and heated at 150 °C for 2 h. The surface properties of the activated charcoal (surface area 627 m 2 g −1 , pore volume 0.39 m 3 g −1 , Bronsted sites 118.23 μmol g −1 , and Lewis sites 104.86 μmol g −1 ) and the adsorption capacity for impurities in H 3 PO 4 -pretreated crude glycerol were investigated. The activated charcoal exhibited the most suitable surface properties for the purification of pretreated crude glycerol, attaining a 95.99% glycerol concentration (by GC) using 10 g/L with gravity filtration through a column at room temperature over a 48-h period. The purified glycerol was characterized by GC/MS, 1 H- and 13 C-NMR, and DSC and TG analyses. The activated charcoal was regenerated by washing with methanol and hexane and heating to 150 °C for 5 h. The activated charcoal could be re-used three times to remove all of the pigments before it was necessary to re-activate the charcoal by heating with ZnCl 2 .