Analyses - process chemicals & materials

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

• 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: To understand the charge balance and potential impact on precipitation and flocculation processes.  
Carboxylic acid and uronic acid content: These organic acids affect the ion balance and can influence chemical consumption in subsequent steps.  
ASA (alkenyl succinic anhydride, total content): Important for evaluating the use of sizing agents and their effectiveness.  
Carbohydrates (total content): Provides an overview of the organic content and any losses of valuable components.  
Lignin content: Affects colour, purity, and downstream purification needs.  
Amount of optical brightening agent: Determines how much optical brightening agent is present and affects optical brightness.

White water: anion content, cation demand, carboxylic acid content, uronic acid content, ASA (total), carbohydrates (total), lignin content, amount of optical brightener and starch content.

Lime: amount of free lime, metal content (sodium, magnesium, calcium, manganese, iron, aluminium, silicon, phosphorus, sulphur) and acid soluble sodium.

Tall oil: acid number, neutrals (non-saponifiables), composition of fatty and resin acids, water content, ash content, total sulphur and total sodium.

Soap: Tall oil (maximum theoretical yield in soap), lye content, calcium (important for e.g. scales), dry matter and calorific value.

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.

RISE can analyze gases such as sulfur and pollutants. We 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?

Metals analysed

• Calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg) and manganese (Mn) 
  These analyses are conducted according to SCAN-CM 38. The metals occur naturally in wood raw material or are introduced via process chemicals. 
• Potassium (K) and sodium (Na) 
  Analysis according to SCAN-CM 63. These alkali metals play a central role in lye balance and the salt load of the boiler system. 
• Cadmium (Cd) and lead (Pb) 
  Analysis according to SCAN-CM 54. These heavy metals normally occur at very low levels but are strictly regulated due to their toxicity and environmental impact.

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) – may indicate impact from chemicals, filter media or equipment. 
• Barium (Ba) – occurs in certain processes and can contribute to precipitations along with sulphate ions. 
• Cobalt (Co) and chromium (Cr) – relevant for process monitoring and equipment wear. 
• Phosphorus (P) – central in the analysis of certain additives, e.g. in dispersion adhesives or biological by-products. 
• Silicon (Si) – important in analyses of fillers, ash content or silicon-related precipitations.
• Zinc (Zn) – can occur as a contaminant from coatings or chemicals and affects microbiological growth as well as surface properties.

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.