TECHNICAL LIGNINS : Physico-chemical characterisations

General informations

In the frame of the Biorerefinery concept application to pulp mills, CTP has developped a strong expertise in technical and industrial lignins, since 2010.

In additions of lignin isolation and purification competences (ie Tailor-made lignin isolation – Laboratory and pilot scale productions), the IntechFibre team, with the support of the analytical Laboratory, proposed several analytical tools to qualify the lignin samples, especially for their applications.

Thus, a complete product specification sheet can be fulfilled to:

• Kraft and soda lignins, lifgnosulfonates organosolve lignins, as well as hydrolytic lignins (ie from 2dG biorefineries).
• Dry or wet powders, lignin in suspension or in solution (in aqueous or organic solvent).

Involved in ISO committees, CTP takes part in the new work item projects, and have proven methods.

Laboratory testings

Purity and contaminants

• Dry matter content according to NF EN ISO 638 (2008) – oven drying method at 105°C,
• Lignin content: Acid Insoluble Lignin content (AIL, or Klason Lignin) and Acid Soluble Lignin (ASL) according to the NWIP-ISO / ISO-DIS 21436 (2020) issued from respectively Tappi T22 om02 and Tappi UM250,
• Minerals contents according to ISO 1762 (2019) – Ash contents on ignition at 525°C,
• Sodium and potassium contents by ICP-OES dosage, according to ISO 11 885 (2007) - after mineralisation with HCl/HNO3 under micro-waves,
• Carbohydrates composition according to NWIP-ISO / ISO-DIS 21437 (2020) and issued from SCAN CM71 (2009) based on acid hydrolysis and HPLC analysis of monosaccharides (Glu, Man, Gal, Xyl, Ara),
• Organic sulphur content, after minerals sulphurous components determination by HPLC Dionex, and compared to the total sulphur by ICP-OES.

Macro-structure

• Particles size distribution and D50 determination of lignin powders or suspension, by image analysis using Malvern-Sysmex FPIA 3000,
• Molecular weight distribution with Mw, Mp, Mz determination and polydispersity evaluation (DP) using SEC-LiCl/DMAc-UV system and/or SECNaOH-UV system,
• Aromatic H, G, and S units composition and S/G ratio by Pyr-GC/MS using Pyrola 2000 Pt filament pyrolyser.

Functionality

• Sulfonic (-SO3-), carboxylic (-COOH) and phenolic (-OHAr) groups determination by potentiometric dosage using TnBAH (expressed in mmol/g);
• Total phenols in EtOH/water solution by Folin-Ciocalteu dosage express in eq. vanillin or mmol of OHAr/g.

Energy values and thermal properties

• Elemental analysis (CHONS) and O/C vs H/C ratios, using VarioMicroCube Elementar;
• High Heating Value (HHV) measurement using calorimetric bomb according to NF EN ISO 1928, and calculation of Low Heating Value (LHV);
• Glass temperature transition (Tg) measurement using a DSC Q2000-TA Instrument.

Usage properties and application testings

• Anti-oxidant capacity using DPPH test, expressed in IC50 (% of a solution at 10 g/L),
• Water solubility testings of lignin suspension after centrifugation/filtration,
• pH of an aqueous lignin suspension at 10% (w/v).