عنوان مقاله [English]
Background and objectives:
One of the common problems in the papermaking process is compounds and unwanted by-products such as pitch, sticky and foreign pollution in paper that each of these materials may come from various sources. The wood as raw material for pulping is an agent of these problems; because wood have contained hydrophobic materials such as wax, lipids, fatty acids, resin acids, hydrocarbons and etc. Pitch is the term that produce in the papermaking process and leads to considerably problems. The main destructive impacts of pitch, including blocking and hang lace to felt dewatering or drying cylinders occurs that creates holes in the paper. Nowadays, some of the material to removal these problems on an industrial scale is used.
Material and methods: In this study, after obtaining extractive compounds from bleached and unbleached CMP pulp, pulp were treated by 0.2 units, equivalent of 0.001 g of esterase enzyme in the water condition (H2O) and consistency of 8% at 50 0C for 45 min with mechanical mixing. Enzyme treatment for the unbleached and bleached pulp was done as separation stage; therefore, the effect of enzyme treatments in pulps using gas chromatography-mass spectrometry (GC/MS) was studied.
Results: Generally, results of this study showed that treatment use with ethanol solvent, bleaching process leads to increasing the amount alkanes, 1 and 2 benzene di-carboxylic acid derivatives, alcohols, silica compounds and minor amounts of aldehydes and as well as lower the esters fatty acids, phenolic and ketones derivatives. There is also a trend in the presence of the enzyme except that ketones were not in pulp and fatty acids increased. Increase of silica compounds is due to three combinations of enzymes. In treatment with use of di-chloromethane solvent, bleaching process leads to increase of alkanes, ketones and silica compounds and reducing the fatty acids, esters of fatty acids, 1 and 2 benzene di-carboxylic acid derivatives, alkenes, aldehydes and phenolic derivatives. There is also a trend for the enzymes with the exception of aldehydes, alcohols, phenolic derivatives, ketones and amides not observed in any of the two pulp that of their destruction. In treatment with use of toluene solvent, the impact of bleaching as increasing of halo-alkanes, esters of fatty acids, 1 and 2 benzene di-carboxylic acid derivatives and aldehydes and reducing of alkanes and phenolic derivatives not observed. The use of enzymes in this solvent and in the unbleached pulp, high amounts of 1 and 2 benzene di-carboxylic acid derivatives, aldehydes and alcohols was presence in pulp.
Conclusion: According to the results obtained from GC/MS, it can be said that esterase enzyme has good performance relatively compared to solvents. As previously mentioned the deposition of extractives in pulp and paper equipment leads to reduce the run-ability of the papermaking machine, causing a tear in the paper and eventually disability of operations and is involved in major economic losses. Triglycerides wood, especially in the factories that used softwoods as raw material, play an important role in in the formation of pitch deposits. Therefore, the use of enzyme systems could have a key role in controlling of pitch.