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Validity test of UV absorption method for determination of dissolved lignin in pulping process filtrates
The chemical oxygen demand (COD) test is commonly used to indirectly measure the amount of organic compounds in water, and is often used in the pulp and paper industry when evaluating the washing efficiency. When analyzing COD compounds in water solution, the dissolved compounds are completely oxidized with Potassium dichromate in the presence of Mercuric sulfate. Because of environmental reasons and the roughness of the COD test other methods has been developed in order to analyze the impurity in a pulping process filtrate. One example is the determination of dissolved lignin by UV absorption at 280 nm.
In order to determine the COD content of a pulp sample the washable COD is leached into water solution under specified conditions and the resulting filtrate is analyzed. COD can be calculated from the dilution made and the amount of dry pulp used. The leaching conditions are specified in two different SCAN-standards as well as in three different internal Metso standards with variations.
This thesis work aims at testing the reliability of the UV absorption method. Filtrates from different wood species (for example pine, birch, eucalyptus, acacia, bagasse, straw) as well as filtrates with different pH, from different process stages should be studied. To be successful, the thesis worker needs to develop a deeper understanding of the behavior of dissolved organic compounds in filtrates and pulps (effect of time, temperature, pH and oxygen access) during storage. It is also of interest to find a unified standard for the extraction of soluble materials from the pulp sample. The thesis work can be divided into
• Literature search
• Preliminary experimental work
• UV absorption tests
• Report writing (English)
The thesis worker should have a Chemistry background for example a Master of Science Chemical Engineering. Experience of laboratory work as well as some insight into pulping processes is beneficial.
The thesis work will be performed at Metso Technology Center in Sundsvall, and is estimated to 20 weeks.
Andreas Averheim, Research Engineer, email@example.com, 060-16 52 23,073-356 0578
Enhet: Metso Fiber business line, Sundsvall
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