Chemical analysis – biomass to product

Cellulose is essential in bio-based products, so process chemicals must not leave harmful residues. Contaminants from bleaching, cooking and dewatering need to be controlled. Targeted analyses of residual chemicals, pH and chlorine contamination ensure quality and sustainability. Typical samples include lime, liquors, soap, tall oil, backwater and methanol. A special package is available for incrustation risk. Careful monitoring supports safe, circular cellulose products free from harmful substances.

Jonas Forsberg

Wood & pulp

Analyses include fibre content, residual alkali, sulphur compounds, oxalate, chlorides, metals, carbohydrates, lignin, tall oil, terpenes, hydroxy and volatile acids, plus dry matter and ash.

Scaling risk increases with high extractive levels, causing operational issues and maintenance costs. Key parameters to monitor include carbonate, sulphate, oxalate, calcium, sodium, aluminium, silicon and dry matter to optimise processes and prevent scaling.

Metal analyses include calcium, copper, iron, magnesium, manganese, potassium, sodium, cadmium and lead. For broader or more sensitive multi-element analysis, ICP-OES is used to quantify multiple metals simultaneously in process liquors, solids, extracts and ash. Common ICP-OES targets are aluminium, barium, cobalt, chromium, phosphorus, silicon and zinc.

Gas analyses include components such as hydrogen sulphide (H₂S), carbon dioxide (CO₂), sulphur dioxide (SO₂) and other volatile organic and inorganic substances. These analyses are important for monitoring emissions, ensuring process control and meeting environmental requirements.

Inorganic compounds are analysed using highly sensitive methods to identify salts, metals, oxides and anions, even at very low concentrations. Both qualitative (identification) and quantitative (concentration) analysis are offered. Instrumental methods such as GC-MS, HPLC, ICP-MS and FTIR enable detection down to ppm and ppb levels, which is crucial for trace analysis and residue control.

Microanalysis of particles and deposits: Using SEM-EDS, we can analyse solid particles, spots and incrustations to determine their composition and origin.

Jonas Forsberg

Process liquids

Black liquor from the kraft pulp process contains organic and inorganic components that are analysed to optimise recovery, energy efficiency and process balance. Key parameters include fibre content, residual alkali, sulphur compounds, total sulphur, oxalate, chlorides, metals, carbohydrates, lignin (including molecular weight), tall oil and terpenes, hydroxy and volatile acids, as well as dry solids and ash.

White and green liquor: White liquor is used directly in the cooking process, while green liquor is an intermediate stage in the recovery cycle. To maintain a stable and efficient chemical balance, precise analyses are required for alkali content (total, active and effective), carbonates, sulphur components (sulphide, sulphite, sulphate and thiosulphate), total sulphur, potassium and sodium levels, chlorides and metal content.

Process water: In process water from the pulp industry, it is essential to analyse parameters that affect process stability, efficiency and final product quality. Key factors include anion content and cation demand, carboxylic and uronic acids, total ASA (alkenyl succinic anhydride), carbohydrates, lignin and the amount of optical brightener.

White water is analysed for anions, cation demand, carboxylic and uronic acids, ASA, carbohydrates, lignin, optical brightener and starch. Lime is checked for free lime content, metal levels (Na, Mg, Ca, Mn, Fe, Al, Si, P, S) and acid-soluble sodium. Tall oil is assessed for acid number, neutral substances, fatty and resin acids, water and ash content, as well as total sulphur and sodium. Soap is analysed for theoretical tall oil yield, alkali, calcium, dry content and calorific value.

Methanol and impure condensate analyses focus on methanol, water, ammonium, total nitrogen, TRS (hydrogen sulphide, methyl mercaptan, dimethyl sulphide, dimethyl disulphide) and total sulphur. Terpenoids, including monoterpenes such as α-pinene, β-pinene, 3-carene and limonene, as well as mono-, sesqui- and diterpenoids, are also assessed. GC-MS screening identifies volatile compounds affecting odour, quality and environmental impact.

Jonas Forsberg

Organic substances

Organic acids and related substances are analysed to assess decomposition and process quality. Common acids are levulinic acid, ethanol, glycerol, lactic acid, formic acid and acetic acid, while furan derivatives such as HMF and furfural indicate carbohydrate decomposition. Components can also be quantified in black liquor to evaluate the cooking process.

Organic compounds and extractives are analysed in forest raw material, process liquids and by-products. The focus is on lignans, fatty and resin acids, sterols, steryl esters, triglycerides, as well as process chemicals such as anthraquinone. Rosin is assessed for its impact on bonding and odour. Carbon and sulphur compounds, including methanols, aldehydes, thiophenes and disulphides, are also included due to their significance for process performance and environmental impact.

Organic acids are analysed to assess degradation and process quality. Common examples include levulinic acid, ethanol, glycerol, lactic acid, formic acid and acetic acid, while HMF and furfural indicate carbohydrate breakdown. Components can be quantified in black liquor to evaluate the cooking process.

Scaling

Scaling: High levels of extractives increase the likelihood of deposits, which can cause operational disturbances and costly maintenance. It is therefore essential to analyse key parameters such as carbonate, sulphate, oxalate, calcium, sodium, aluminium, silicon and dry solids to optimise the process and prevent scaling problems.

Microanalysis of particles and deposits: Using SEM-EDS, we can analyse solid particles, spots and scaling to determine their composition and origin.

RISE

Textile

Viscosity measurement is used to assess molecular weight and degradation in cellulose-based textiles, particularly during recycling. Fibre analysis using light microscopy provides information on fibre type and dimensions, while SEM reveals morphology and defects. Metal content is determined using ICP-OES or ICP-MS; common metals include copper, zinc, chromium, lead, nickel, cadmium, iron, aluminium, sodium and potassium. Metal analysis is important for environmental and health considerations, as well as for evaluating recyclability.