Exjobbsförslag från företag

Detta är ett uppsatsförslag hämtat från Nationella Exjobb-poolen. Klicka här för att komma tillbaka till samtliga exjobbsförslag.

Förslaget inkom 2007-08-21

Minimising the sulphur content of kraft lignin

OBS! ANSÖKNINGSTIDEN FÖR DETTA EXJOBB HAR LÖPT UT.
Aim
The aim is to determine how the sulphur exists in kraft lignin and how to minimize the sulphur content.

Background
Lignin is a phenolic macromolecule. The precise structure is not known, but lignin is commonly divided into three types depending on the substituents in the phenol ring; p-hydroxyphenyl, guaiacyl and syringyl. The amount of these basic structures as well as the degree of branching differs between sources including morphological origin. About 20 – 30% of the wood is lignin, the amount in softwoods in general being higher than in hardwoods.
During kraft pulping, the lignin is partly degraded and most of it dissolved into the black liquor, where the lignin constitutes the main organic part. Today the black liquor is evaporated and combusted in the recovery boiler for production of energy and for recovery of process chemicals. However, in spite of the efficient process, the recovery boiler has become a bottleneck for production increase. In addition, there is also a growing interest in exploiting more of the wood of economical and environmental reasons. A new process to recover the lignin in the black liquor has open a possibility for using lignin as a fuel in a broader sense, but also to refine lignin for other applications such as chemicals and materials.
Lignin isolated from black liquor commonly contains sulphur. The sulphur content is an obstacle for combustion of lignin in small scale units lacking purification of the gaseous emissions. Besides of sulphur, the ash content reduces the value of lignin for other applications such as raw material source for carbon fibre production.

Task
The experimental part, which will be preceded by a literature survey, will include extractions, separation and characterisation of kraft lignin, previously isolated from black liquor. The results and the literature information will be compiled in a report (in English) and summarized in an oral presentation.

This work is mainly intended for students interested in organic and analytical chemistry and who want to take part in the development towards utilising lignin for new applications.


For further information please contact

Elisabeth Sjöholm
STFI-Packforsk, Chemical Analysis
Phone: 08 6767 448
Mobile:0768 767448
[email protected]

  GÅ TILL XJOBB.NU FÖR FULLSTÄNDIG INFO OM DETTA EXJOBB




Informationen om uppsatsförslag är hämtad från Nationella Exjobb-poolen.