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Research on Bio-mechanical Pulping of Corn Stalk Barks

Author: WangFangFang
Tutor: HuangFeng
School: Shandong Institute of Light Industry
Course: Pulp and Paper Engineering
Keywords: corn stalk barks selective degradation biomechanical pulp Trametes hirsuta lg-9
CLC: TS743
Type: Master's thesis
Year: 2011
Downloads: 34
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Abstract


Corn stalk barks contain 37.62% nitric acid-ethanol cellulose and their weight-average fiber length is 0.987, so they are more suitable for using as paper-making materials than the whole corn stalk. Besides, to avoid the high electric consumption of mechanical pulping and environmental pollution caused by chemical pulping in current pulping and paper-making industry, the thesis adapted the new lignocellulosic materials—corn stalk barks as raw material to carry out the research on biomechanical pulping.Four stains that produced colored reaction were isolated from planted ground of corn at ChangQing district in Jinan by Bavendamm-PDA plate. Among the five stains obtained from the state key laboratory of microbial technology in Shandong university, Bavendamm-PDA plate of Phanerochaete chrysosporium-25 and Phanerochaete chrysosporium-14 was negative, that of Trametes hirsuta lg-9,Trametes versicolor,Irpex lacteus was positive. The experiment of degradation of corn stalk barks by the nine strains showed that the sequence of selective degradation on corn stalk barks was: Trametes hirsuta lg-9 > Sd > P.C.-14 > P.C.-25 > Trametes versicolor>Sc.The strongest selective degrading strains on corn stalk barks isolated—Trametes hirsuta lg-9 was applied to corn stalk barks biomechanical pulping. Mechanical pulpling of corn stalk barks was performed after pretreated in no-exogenous air or aeration by different age inoculums gained by different cultivated method. The results indicated that in no-exogenous air, the strength of pulp made from corn stalk barks treated by young age inoculums was superior to samples treated by old age inoculums; with regard to the same age inoculums, the strength of sample treated by solid static cultivated inoculums excelled those treated by liquid shaking cultivated inoculums. In continuous aeration, further research was required due to the discrimination of the beating degree. When corn stalk barks were inoculated by solid static inoculums, the weight loss in no-exogenous air was less than that in continuous aeration and its strength property was also better than the latter. While corn stalk barks were treated by liquid shaking cultivated inoculums, the outcome was opposite. Pretreatment by Trametes hirsuta lg-9 caused the decrease of brightness and light scattering coefficient of corn stalk barks mechanical pulp and the increase of light absorption coefficient. And the energy consumption of corn stalk barks after treated by Trametes hirsuta lg-9 in the two-stage refining condition studied reduced from 70% to 85%. In addition, the research discovered the positive linear correlation between the strength property of biomechanical pulp of corn stalk barks pretreated by Trametes hirsuta lg-9 and the ratio of increment of fine caused by beating to increment of water retention value was significant.The research of effect of pretreatment time on biomechanical pulping of corn stalk barks treated by Trametes hirsuta lg-9 indicated during the course of pretreatment of corn stalk barks, Trametes hirsuta lg-9 produced xylanase, cellulase, and laccase and the sequence of yield of enzyme was: xylanase>cellulase>laccase. The ratio of producing enzyme increased quickly in early period, slowed down in middle period, and decreased in last stage. And the pretreatment by Trametes hirsuta lg-9 caused change of pH of the fermentation system. The result of energy consumption estimation during refining indicated the electric consumption constantly reduced with time, and ifα=0.1 was chosen as th significant level, there was no correlation between the energy consumption and yield of enzyme produced in the course of pretreatment, but there was linear correlation between the energy consumption and the relative absorption intensity of 3414cm-1 and 1653cm-1 in infrared spectrum of corn stalk barks pretreated by Trametes hirsuta lg-9. The reason why led to the reduction of strength of corn stalk barks biomechanical pulp by Trametes hirsuta lg-9 as pretreatment time was that the continuous accumulation of cellulase brought about the depolymerization of cellulose, and eventually caused the decrease ofα-cellulose content. The pretreatment by Trametes hirsuta lg-9 raised the number of aliphatic carbonyl group and carbonyl group conjugated to benzene ring, so the light absorption coefficient of corn stalk barks biomechanical pulp by Trametes hirsuta lg-9 increased, and finally pulp brightness decreased. During the pretreatment of corn stalk barks by Trametes hirsuta lg-9, the degradation of the guaiacyl unit was more than that of the syringyl unit, and in early period the degradation of crystalline region predominated, while in latter period the degradation of amorphous region was principal. Microscopic observation of corn stalk barks pretreated by Trametes hirsuta lg-9 revealed invasion of hypha of Trametes hirsuta lg-9 began with epidermal cell and gradually penetrated into parenchymas and vascular bundles.

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CLC: > Industrial Technology > Light industry,handicrafts > Paper Industry > Pulping process > Pulping
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