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An integrated biorefinery process based on acidic leaching, alkaline treatment and concentrated sulfuric acid hydrolysis was set up for the simultaneous recovery of lignin, hemicelluloses, silica, and cellulose nanocrystals (CNCs) from Arundo donax and rice husk. These fractions can serve as viable source of bio-chemicals with potential high-value applications. A chromatographic and spectroscopic characterization demonstrated that a combined acidic-alkaline treatment enhanced the degradation of lignin-carbohydrates complexes releasing lignin and hemicelluloses in higher yield and purity than the sole alkaline treatment. The remaining cellulose rich solid was bleached through a totally chlorine free process, and then hydrolyzed for cellulose nanocrystals isolation. A. donax cellulose nanocrystals were extracted and characterized for the first time in literature. Moreover, from rice husk, pure amorphous silica was obtained almost in 90% yield and 99% purity, avoiding incineration. In term of mass balance, it was possible to refine the investigated biomasses for the production of lignin, hemicelluloses, silica and CNCs in almost 40% overall yield. more...

The recalcitrance of lignocelluloses toward enzymatic hydrolysis necessitates pretreatments. Ionic liquid pretreatment with 1-allyl-3-methylimidazolium chloride ([amin]Cl) was applied to risk husk and cellulose-containing fractions were recovered from the ionic liquid solutions by acidic, alkaline, and alkaline-acidic regeneration respectively. Enzymatic hydrolysis of the recovered materials was carried out and results demonstrated that: (i) acidic regeneration was not substantial to ensure enhanced enzymatic digestibility; (ii) alkaline regeneration increased the enzymatic hydrolysis; (iii) alkaline-acidic regeneration led to an almost complete hydrolysis of the carbohydrate fraction. The obtained results were rationalized by means of chromatographic analyses of soluble fractions collected after the different regeneration processes: the removal of hemicellulose, which increased going from the acidic to the alkaline-acidic regeneration, seemed to play a crucial role in enhancing the rice husk saccharification. more...

Novel processing methods and product concepts are required to extend the role of lignin for future biomass and biofuel applications in emerging platforms such as the biorefinery. The possible strategies of lignin valorisation are focused into two main directions, namely the selective functionalisation of the lignin polymer or in its oxidative depolymerization to get polyfunctional monomeric compounds. Here we report a panel of biocatalysis, organometallic catalysis, biomimetic catalysis and plasma oxidation processes developed by our research group for the activation of the environmental friendly oxidants oxygen and hydrogen peroxide in the oxidative functionalisation of lignin and lignin model compounds. © 2010 Elsevier B.V. All rights reserved. more...

Anaerobic erosion bacteria can slowly degrade waterlogged wood, causing a loss of cellulose and hemicellulose. During this process, lignin can also be altered. For this reason, the chemical characterization of waterlogged archaeological wood is crucial for both the elucidation of the degradation processes and also the development of consolidation and conservation procedures. The complex structure of wood makes it practically impossible to dissolve wood in its native form in conventional molecular solvents. Ionic liquids can provide a homogeneous reaction medium for wood-based lignocellulosic materials. Highly substituted lignocellulosic esters and phosphite esters can be obtained under mild conditions by reacting pulverized wood dissolved in ionic liquid with either acyl chlorides or dioxaphospholanes in the presence of pyridine. As a result, the functionalized wood develops an enhanced solubility in molecular solvents, allowing for a complete characterization by means of spectroscopic and chromatographic techniques. In this study, archaeological woods and reference sound woods of the same taxa (Quercus and Arbutus unedo), along with the corresponding extracted lignin, were fully characterized by means of phosphorus NMR spectroscopy, two dimensional NMR spectroscopy and GPC analysis. The samples were collected from the Site of the Ancient Ships of San Rossore (Pisa, Italy), where many shipwrecks dating from 2nd century BC to 5th century AD have been discovered. The results highlighted a deeper and faster depolymerization of the polysaccharide matrix against a limited degradation of the lignin fraction. The use of innovative solvent system as the ionic liquid [amim]Cl enables to highlight chemical and morphologic changes in wood composition avoiding further degradation. more...

Historical or archaeological wooden objects are generally better conserved in wet environments than in other contexts. Nevertheless, anaerobic erosion bacteria can slowly degrade waterlogged wood, causing a loss of cellulose and hemicellulose and leading to the formation of water-filled cavities. During this process, lignin can also be altered. The result is a porous and fragile structure, poor in polysaccharides and mainly composed of residual lignin, which can easily collapse during drying and needs specific consolidation treatments. For this reason, the chemical characterization of archaeological lignin is of primary importance in the diagnosis and conservation of waterlogged wood artifacts. Current knowledge of the lignin degradation processes in historical and archaeological wood is extremely inadequate. In this study lignin extracted from archaeological waterlogged wood was examined using both Py-GC/MS, NMR spectroscopy and GPC analysis. The samples were collected from the Site of the Ancient Ships of San Rossore (Pisa, Italy), where since 1998 31 shipwrecks, dating from 2nd century BC to 5th century AD, have been discovered. The results, integrated by GPC analysis, highlight the depolymerization of lignin with cleavage of ether bonds, leading to an higher amount of free phenol units in the lignin from archaeological waterlogged wood, compared to sound lignin from reference wood of the same species more...

The present paper deals with a laboratory-scale study of anaerobic treatment of two commercial mixtures (LS2, LT7) of alcohol ethoxylates with 8-14 carbon atoms and 2 and 7 ethoxy groups. Tests were carried out in batch, with a 2 g 1-1 single dose, and in semibatch, with daily 0.2 g 1-1 doses. The behaviour of the tested mixtures was different: anaerobic sludge adsorption was the main removal process for LS2, while adsorption was less significant and biodegradation was more important for LT7. These differences appeared to be mainly related to the ethoxy portion length determining the extent of biodegradability and adsorption. © 2002 Elsevier Science Ltd. All rights reserved. more...

The present paper deals with a laboratory-scale study of anaerobic treatment of two commercial mixtures (LS2, LT7) of alcohol ethoxylates with 8-14 carbon atoms and 2 and 7 ethoxy groups. Tests were carried out in batch, with a 2 g 1-1 single dose, and in semibatch, with daily 0.2 g 1-1 doses. The behaviour of the tested mixtures was different: anaerobic sludge adsorption was the main removal process for LS2, while adsorption was less significant and biodegradation was more important for LT7. These differences appeared to be mainly related to the ethoxy portion length determining the extent of biodegradability and adsorption. © 2002 Elsevier Science Ltd. All rights reserved. more...

Conjugates containing benzoyl residues bound to poly-l-lysine (l-PLL) and l-lysine were prepared. The characterization was performed by UV spectrophotometry, 1H NMR, size-exclusion chromatography (HPSEC) and circular dichroism. The principal component analysis method was used in order to evaluate the relationships among the retention time in HPSEC and several parameters of the substrates. The results of this approach suggest that the set of experimental variables give different significant information. A molecular dynamics calculation of a model of these conjugates shows folding of the polypeptide backbone upon derivatization with the 4-methylbenzoyl group. Multivariate analysis and molecular dynamics simulations are important tools for the interpretation of the physicochemical characteristics (including those involved in separation science) of hapten-polypeptide and hapten-protein conjugates used in clinical chemistry and in biotechnology. more...