• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.43 no.2
• /
• pp.1-8
• /
• 2011

The presence of high silica in bamboo hinders the use of this material for production of rayon grade pulp. Research has been carried out to overcome this deficiency and improve quality of rayon grade pulp with the modification in pulping and bleaching process. Effect of acid boosted water prehydrolysis, sulphuric acid pre-treatment of unbleached pulp, chlorination stage at lower pH and treatment of bleached pulp with $SO_2$ water were evaluated. Acid boosted water prehydrolysis of chips reduces prehydrolysis time by 50 minutes as compared to water prehydrolysis. Treatment of unbleached pulp with sulphuric acid reduces ash, acid insoluble, silica, calcium and iron contents of the pulp by 56, 31, 82, 84 and 60% respectively. The addition of acid, increase in kappa factor in $C_D$ stage and combination of both were effective in removing silica in the pulp. Treatment of final bleached pulp with $SO_2$ water removes silica to a great extent and improves optical properties of the pulp as compared to $H_2SO_4$ or PAA. Pretreatment of the pulp with acid and modification in the bleaching process can reduce silica substantially and improve the quality of rayon grade bamboo pulp.

• Journal of Korean Society of Forest Science
• /
• v.98 no.3
• /
• pp.305-310
• /
• 2009

Yellow poplar was selected a promising biomass resources for bio-ethanol production through alkali prehydrolysis, enzymatic saccharification and fermentation using commercial cellulase mixtures (Celluclast 1.5L and Novozym 342 mixtures) and fermenting yeast. In alkali prehydrolysis, 51.1% of Yellow poplar biomass remained as residues, which chemical compositions were 82.2% of cellulose, 17.6% of xylan and 2.0% of lignin. In alkali prehydrolysis process, 96.9% of cellulose, 38.0% of xylan and 5.7% of lignin were remained. Enzymatic saccharification by commercial cellulases led to 87.0% of cellulose to glucose and 87.2% of xylan to xylose conversion. Produced glucose and xylose were fermented with fermenting yeast (Saccharomycess cerevisiae), which resulted in selective fermentation of glucose only to bio-ethanol. Residual monosaccharides after fermentation were consisted to 0.4-1.4% of glucose and 92.1-99.5% of xylose. Ethanol concentration was highest for 24 h fermentation as 57.2 g/L, but gradually decreased to 56.2 g/L for 48 h fermentation and 54.3 g/L for 72 h fermentation, due to the ethanol consumption by fermenting yeast.

• Journal of the Korean Ceramic Society
• /
• v.30 no.12
• /
• pp.987-992
• /
• 1993

In order to synthesize the heat resistance ceramics of LAS system, we studied on preparing the fine powder with homogeneity by sol-gel method using metal alkoxide. Various results were obtained depending on the composition and process. When the amount of H2O added at initial stage is higher than 10mol/$\ell$, and when the amount of catalyst is 0.1mol/$\ell$, the particle size of synthesized hydrate becomes finer. On condition that partial prehydrolysis time of TEOS is more than 50 hours, the monosized fine powder is obtained(below 1${\mu}{\textrm}{m}$).

• Applied Chemistry for Engineering
• /
• v.10 no.7
• /
• pp.963-968
• /
• 1999

The global environmental problems have been caused by the release of CFCs. Therefore, methods for safe destruction of recoverd CFCs will be eventually needed. The objective of this study was to develop and test a catalyst operating at a mild condition for the decomposition of CFC-113. In this work, catalytic oxidative decomposition of CFC-113 was carried out over aerosol $TiO_2/SiO_2(ATS)$ catalysts prepared by the sol-gel method. All ATS catalysts(Ti/Si mol ratio=1, 2, 2.33, 4) showed high initial activity. However, the deactivation of ATS catalysts was found that more remarkable due to an attack of fluorine and the destruction of ATS structure(Si-F reaction) from analyses of SEM-EDX, XRD than $TiO_2/SiO_2(ATS)$ catalyst prepared by the precipitation method. ATS catalysts prepared by more acidic prehydrolysis condition were found to have still more activity and longer life-time by increasing of acidity. The activity of ATS catalyst also depend on the content of $TiO_2$. There was reason that the acidity of the ATS catalyst was increased with the increased content of $TiO_2$ from 50 to 80 mol %. Solid superacid catalyst ($ATX/SO_4{^{2-}}$) modified with $H_2SO_4$ solution was prepared for high activity and lower deactivation. The reaction of $ATS/SO_4{^{2-}}$ catalyst also exhibited even higher activity and lower deactivation than the original ATS catalyst. It is suggested that the addition of the sulphate species clearly inhibit the deactivation.

• KSBB Journal
• /
• v.14 no.6
• /
• pp.707-712
• /
• 1999

We have produced new-structured oligosaccharides using mixed-enzyme reactor of dextransucrase from Leuconostoc mesenterides B-512FMCM and ${\alpha}$-amylase. When the concentrations of sucrose and starch were 10%(w/v) and 5%(w/v), respectively, the maximum yield of oligosaccharides with both dextransucrase(100U) and ${\alpha}$-amylase(1000U) was 66.4%. The activity of dextransucrase in mixed-enzyme reactor was increased about 2.5 times by acceptor reaction with starch hydrolyzates. As the activities of dextransucrase:${\alpha}$-amylase were increased from 20U:200U to 500U:5000U, the amount of polymer was increased and the yield of oligosaccharides was decreased. By the addition of sucrose into mixed-enzyme reactor following the prehydrolysis of starch with ${\alpha}$-amylase, the yield was increased up to 12% compared with that of mixed-enzyme reactor without the addition of starch hydrolyzate. New structured-oligosaccharides showed heat resistance up to 140$^{\circ}C$ and was stable in acidic condition at pH 3~6.

• Journal of environmental and Sanitary engineering
• /
• v.13 no.1
• /
• pp.16-25
• /
• 1998

Laboratory-scale experiment using anaerobic fluidized bed reactor was carried out to investigate the prehydrolysis step with caustic soda on the treatment efficiency of anaerobic sludge treatment, since the overall rate-limiting step for the complete anaerobic digestion of sludge was the hydrolysis step by extracellular bacterial enzymes of insoluble polymeric molecules. Reactors received a sludge which had not been pretreated, a 50-50 mixture of pretreated and untreated sludge, and the fully pretreated sludge. Hydraulic retention time of 10, 5, 2.5 days and 1 day were applied with an respective equivalent organic loading rate of 1.17, 2.23, 4.17, 11.24 gCOD/L/d. Reactor with the untreated sludge did not archieve adequate digestion even at the HRT of 5 days, and reactor, which received the 50-50 mixture, operated well at the HRT of 5 days, but began to show signs of unstable digestion at the HRT of 2.5 days. While, reactor, which was fed the hydrolyzed sludge, operated reasonably well at the 2.5 days, but was showing somewhat decrease in removal efficiencies. Results, therefore, have substantiated that the limiting reaction in the anaerobic treatment process is hydrolysis. The soluble COD did not significantly accumulate in the reactor as organic acid form, even when they were highly stressed. It was believed that this resistance to a build-up of organic acids and soluble COD behavior was mainly due to the maintenance of the methane bacteria in the fixed-film system which prevents washout as the organic loading increased. The anaerobic fluidized bed reactor was therefore effective for the digestion of waste activated sludge at short HRT.

• Asian-Australasian Journal of Animal Sciences
• /
• v.25 no.1
• /
• pp.66-74
• /
• 2012

The effects of exogenous fibrolytic enzymes (EFE; a mixture of two preparations from Trichoderma spp., with predominant xylanase and ${\beta}$-glucanase activities, respectively) on colonization and digestion of ground barley straw and alfalfa hay by Fibrobacter succinogenes S85 and Ruminococcus flavefaciens FD1 were studied in vitro. The two levels (28 and 280 ${\mu}g$/ml) of EFE tested and both bacteria were effective at digesting NDF of hay and straw. With both substrates, more NDF hydrolysis (p<0.01) was achieved with EFE alone at 280 than at 28 ${\mu}g$/ml. A synergistic effect (p<0.01) of F. succinogenes S85 and EFE on straw digestion was observed at 28 but not 280 ${\mu}g$/ml of EFE. Strain R. flavefaciens FD1 digested more (p<0.01) hay and straw with higher EFE than with lower or no EFE, but the effect was additive rather than synergistic. Included in the incubation medium, EFE showed potential to improve fibre digestion by cellulolytic ruminal bacteria. In a second batch culture experiment using mixed rumen microbes, DM disappearance (DMD), gas production and incorporation of $^{15}N$ into particle-associated microbial N ($^{15}N$-PAMN) were higher (p<0.001) with ammoniated (5% w/w; AS) than with native (S) ground barley straw. Application of EFE to the straws increased (p<0.001) DMD and gas production at 4 and 12 h, but not at 48 h of the incubation. EFE applied onto S increased (p<0.01) $^{15}N$-PAMN at 4 h only, but EFE on AS increased (p<0.001) $^{15}N$-PAMN at all time points. Prehydrolysis increased (p<0.01) DMD from both S and AS at 4 and 12 h, but reduced (p<0.01) $^{15}N$-PAMN in the early stage (4 h) of the incubation, as compared to non-prehydrolyzed samples. Application of EFE to barley straw increased rumen bacterial colonization of the substrate, but excessive hydrolytic action of EFE prior to incubation decreased it.