title: Organosolv extraction of lignin from hydrolyzed almond shells and application of the delta-value theory.
abstract: The solubility of lignin from hydrolyzed almond (Prunus amygdalus) shells in different acetone, ethanol and dioxane-water mixtures and conditions (extraction time and temperature) was studied. The concept of the solubility parameter (delta-value) was applied to explain the effect of organic solvent concentration on lignin solubility. The organic solvent-water mixture that led to the highest lignin extraction was composed of a 75% vol. of organic solvent for all the solvent series investigated (acetone, ethanol and dioxane). Moreover, the best lignin extraction conditions were a temperature of 210 degrees C and an extraction time of 40 min for the acetone and ethanol series, and 25 min for the dioxane series. The delta-value of the hydrolyzed almond shell lignin [14.60 (cal/cm(3))(1/2)] and that of the organic solvent-water mixtures was calculated. The experimental delignification capacity of the aqueous organic solvents clearly reflected the proximity of their delta-value to that of lignin. The hydrogen-bonding capacity of the solvent-water mixtures was also taken into account.
authors.affiliation: Department of Chemical Engineering, Faculty of Chemistry, University of Murcia, Campus of Espinardo, 30071 Murcia, Spain. quesamed@um.es
authors.forename: Joaquín
authors.initials: J
authors.lastname: Quesada-Medina
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: López-Cremades
authors.forename: Pilar
authors.initials: P
authors.lastname: Olivares-Carrillo
mesh_terms: D018533:Biomass; D005591:Chemical Fractionation / Q000379:methods*; D006868:Hydrolysis; D008031:Lignin / Q000737:chemistry / Q000302:isolation & purification*; D008956:Models, Chemical; D009930:Organic Chemicals / Q000737:chemistry*; D027861:Prunus / Q000737:chemistry*; D012995:Solubility; D012997:Solvents / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D009930:Organic Chemicals; D012997:Solvents; D014867:Water; D008031:Lignin