Analyses – Process chemicals and materials [in cellulose industry]

In the process water from the pulp industry, it is important to analyse several parameters to be able to assess its impact on the stability, efficiency of the process and the quality of the final product.

Examples of important analysis points include:

• Fibre content (total)
• Residual alkali
• Sulphide ion, sulphite ion, sulphate ion and thiosulphate ion
• Total sulphur content
• Oxalate content
• Chloride content
• Metal content
• Carbohydrates (total, polymeric and free monomers)
• Lignin (total and molecular weight distribution)
• Quantity of tall oil and terpene content
• Hydroxy acids and volatile acids
• Dry matter and ash content

White liquor and green liquor characterisation:

• Alkali content (total, active and effective)
• Carbonate content
• Sulphide, sulphite, sulphate and thiosulphate
• Total sulphur content
• Potassium and sodium content
• Chloride content
• Metal content

A high concentration of extractives increases the risk of incrustation on process equipment, which can lead to operational disturbances, reduced heat transfer efficiency and costly maintenance. It is therefore important to analyse key parameters such as carbonate, sulphate, oxalate, calcium (total and dissolved), sodium, aluminium, silicon and dry matter content to optimise process conditions and prevent scaling problems.

In the process water from the cellulose industry, it is important to analyse several parameters to assess its impact on the stability, efficiency, and quality of the final product. Examples of key analysis points include:

• Anion content and cation demand
• Carboxylic acid and uronic acid content  
• ASA (alkenyl succinic anhydride, total content)
• Carbohydrates (total content)
• Lignin content  
• Amount of optical brightening agent

Measuring white water in the pulping process is crucial to optimise fibre recovery and reduce chemical consumption. Control of lime, tall oil and soap is important to maintain chemical balance, improve dewatering and maximise by-product recovery. We can analyse the compounds in:

• White water
• Lime
• Tall oil
• Soap

In addition to basic process parameters, an in-depth chemical analysis is required to optimise the pulping process and control the environmental impact. Important indicators are methanol and water content, ammonium and total nitrogen concentration, and total reduced sulphur (TRS), including hydrogen sulphide, methyl mercaptan, dimethyl sulphide and dimethyl disulphide. Total sulphur content should also be carefully monitored.

Terpenoids such as α-pinene, β-pinene, 3-carene and limonene are analysed to assess the impact on odour, chemistry and the environment. Total levels of mono-, sesqui- and diterpenoids are included. For a complete picture, GC-MS screening of other volatile organic compounds that may affect process and product is performed.

Analysing gases such as sulphur and other pollutants is important to ensure environmental compliance, prevent corrosion and optimise purification processes in pulp production. RISE can analyze and identify:

• Inorganic molecules and of compounds
• Qualitative/quantitative analysis
• Low detection limits
• Dot microanalysis
• Lignans
• Extractive substances - fatty and resin acids, sterols incl. betulinol, steryl esters and triglycerides
• Anthraquinone
• Rosin
• Carbon compounds
• Sulfur compounds

Organic acids: levulinic acid, ethanol, glycerol and lactic acid, formic acid, acetic acid, the furan derivatives hydroxymethylfurfural (HMF) and furfural. We also measure organic acids in black liquors. It is also possible to analyze organic compounds with HPLC.

Do you need analyzes for REACH Regulation?

Analysing metals in the pulping process is important to detect contamination, protect equipment and ensure product quality.

Metals that can be analysed

• Calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg) and manganese (Mn) 
• Potassium (K) and sodium (Na) 
• Cadmium (Cd) and lead (Pb) 

Metals analysed with ICP-OES 

When a broader or more sensitive multi-element analysis is required, we apply ICP-OES, a highly sensitive technique that allows for the simultaneous quantification of multiple metals in a single sample. The method is suitable for the analysis of both process liquids, solid materials, extracts and ash fractions. 

• Aluminium (Al)
• Barium (Ba) 
• Cobalt (Co) and chromium (Cr)
• Phosphorus (P)
• Silicon (Si) 
• Zinc (Zn)

Viscosity measurement of textile materials

Viscosity is a critical parameter for assessing the molecular weight and degradation state of cellulose-based textiles, particularly in recycling processes or regenerated fibre streams.

Fibre analysis by microscopy

To characterise fibre structure, identify fibre blends, or investigate defects and degradation, we use advanced microscopy techniques.

Light microscopy and polarised light microscopy are employed to identify fibre types and measure fibre diameter, surface roughness, and length distribution. Scanning Electron Microscopy (SEM) provides high-resolution images of fibre morphology, revealing surface structures, cracks, deposits, or contaminants. These methods are particularly valuable in comparative material studies, failure analysis, or the development of technical textiles.

Metal analysis in textiles

Textiles may contain metals for various reasons – as components of dyes, functional additives (e.g., antibacterial agents), or as residues from manufacturing and finishing processes.

Using ICP-OES or ICP-MS, we can quantify metal content in textile samples with very high sensitivity. Common analytes include copper, zinc, chromium, lead, nickel, cadmium, iron, aluminium, sodium, and potassium, depending on the material and production methods. Metals in textile materials are of particular interest from environmental and health perspectives, especially in consumer products or when evaluating recyclability and circularity.