Enzyme-based Process Technology For Pitch Control In Thermomechanical Pulp From Pinus Massoniana

Thermomechanical pulp(TMP)pitch is a complex mixture containing fatty acids,resin acids,sterol esters and triglycerides.In papermaking process,these compounds often cause pitch trouble,which coud make the paper machine shutdown and cause other serious harm to the process.So it's very important to explore new enzymes'effects on pulp about the remove of pitch and fiber modification.In this dissertation,the Pinus massoniana pulp was respectively treated using the Panus conchatus XS117 laccase in the presence of HBT and a novel coupled perhydrolase-chemical oxidation technology,then extracted the pitch by soxhlet extraction,and for gas chromatogramphy/mass spectrometry(GC/MS)analysis,besides,the kappa number and whiteness of the Pinus massoniana pulp and the pulp treated with enzymes were determined;At the same time,the pulp fiber was analyzed by ATR-FTIR(Attenuated total reflection flourier transformed infrared spectroscopy)and SEM(Scanning electron microscope).The main results were as follows:1.Laccase-HBT and perhydrolase could make various components of pitch degrade with varying degrees.After treatment with laccase-HBT,hexadecanoic acid,dehydroabietic acid,cholesterol,stigmasterol,cholesteryl oleate and glyceryl triheptadecanoate in the Pinus massoniana TMP were not found,octadecanoic acid were removed by 8.62%;After perhydrolase treated,stigmasterol,cholesteryl oleate and glyceryl triheptadecanoate in Pinus massoniana TMP were not found,the removal rate of hexadecanoic acid was 62.19%,and octadecanoic acid,tetradecanoic acid and cholesterol were respectively removed by 50.07%,49.13%and 45.64%.2.After treatment with laccase-HBT,the kappa number of pulp decreased by 10.74%,and the whiteness improved by 7.62%ISO;After perhydrolase treated,the kappa number of pulp decreased by 10.65%,and the whiteness improved by 10.68%ISO;ATR-FTIR analysis showed that after laccase treated,the pulp fiber 's intensity of absorption peak was almost unchanged,after perhydrolase treated,the stretching vibrations of O-H and C=O decreased,which showed that perhydrolase could oxidize the C=O of cellulose,hemicelliulose and the side chain of lignin.SEM showed that lignin was covered on the fiber surface without two kinds of enzymes treated,the surface of control pulp was relatively smooth,and the fiber was too hard to forminterwoven network structure.For the fiber treated with enzymes,showing a rough and wrinkled surface,which indicated that much of the surface lignin was greatly removed from the fiber surface,thus improving the ability to interweave fibers.