• 펄프종이기술
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• 제33권1호
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• pp.73-79
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• 2001

Stricter environmental demands have increased the need to replace conventional C/D bleaching sequence by chlorine-free sequence. Permanganate is well known as a powerful oxidant and have been used industrially in variable fields. However, it has considered to be difficult to use permanganate as a bleaching reagent because of its strong oxidative effect decreasing the viscosity of pulps extremely. We have tried to use permanganate as a bleaching reagent for KP under the mild condition and it was clear that pernanganate oxidized lignin remained in pulps selectively and increased pulp brightness decreasing K number of pulps with small degradation of cellulose. We have employed the neutral condition in the permanganate bleaching process in this study. In this case, permanganate was converted to manganese dioxide after bleaching reaction. The manganese dioxide is remained in the treated pulp fibers because of its insolublity in water. So it was required to reduction the manganese oxide to manganese ion by using reductants with acid. In this paper, we proposed to use oxalic acid as a reducing reagent converting manganese oxide to manganese ion after bleaching reaction. Oxalic acid plays the role as a reductant and a acid, so post-treatment after bleaching became to be easy by using oxalic acid. On the study using lignin model compounds, it was clear that permaganate react with phenols firstly, after that oxalic acid reduce the manganese oxide to manganese ion in the mixture of permanganate, phenols and oxalic acid. Several lignin model compounds ($\textit{p}$-hydroxybenzaldehyde, vanillin, syringaldehyde, veratraldehyde) are selected to elucidate the effect of substituents on reaction rate and its mechanism with permanganate including oxalic acid in this study. Except for veratraldehyde, the rate of oxidative degradation of phenolic compounds by permanganate with oxalic acid are higher than neutral condition. Especially, the degradation rate of $\textit{p}$-hydroxybenzaldehyde are strongly dependent on pH of reaction mixture. On the other hand, the degradation rate of veratraldehyde are decreased with decreasing pH and main degradation product is veratric acid. This result indicate that pH of bleaching liquor should be kept over 2 to degrade of non-phenolic lignin in the pulps effectively in permanganate bleaching.

• 한국응용곤충학회지
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• 제45권3호
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• pp.363-369
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• 2006

고농도 탄산가스 충전을 통한 식품 해충 방제에서 식품 포장재질과 노출시간이 화랑곡나방과 거짓쌀도둑거저리의 사망률에 미치는 영향을 조사하였다. 사용된 식품포장 재질은 3겹크라프트지(KKK), 2겹 크라프트-1겹 라미네이트 코팅지(KLK), 2겹크라프트-1겹 HD 코팅지였다(KHK). 탄산가스 농도가 85% 로 충전된 실험구(직경 1.2 m)에 투입 하루 후각 재질의 봉투($9.8{\times}9.8cm$) 내 탄산가스 농도는 KKK($26.67{\pm}0.58%$)에서 다른 재질 봉투에 비해 유의하게 높았다. 화랑곡나방과 거짓쌀도둑거저리의 사망률은 KKK 재질의 봉투에서 다른 재질에 비해 유의하게 높았다. 실제 식품보관 창고($9{\times}4{\times}3m$)에서 대형 포대(20 kg)를 대상으로 한 실험에서도 유사한 결과를 얻었다. 포장재질의 영향은 화랑곡나방 보다 내성이 강한 거짓쌀도둑거저리에서 두드러졌다. 화랑곡나방과 거짓쌀도둑거저리의 사충률은 누적 농도시간 (${\int}_{0}^{t}c{\times}tdc{\approx}{\sum}$농도${\times}$시간)에 회귀하였다. 이 결과를 토대로 탄산가스 충전에 의한 방제효과를 식품포장 재질, 식품의 종류, 누적농도시간과 연관하여 고찰하였다.

• Journal of Microbiology and Biotechnology
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• 제22권12호
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• pp.1636-1643
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• 2012

Enzymatic pre-bleaching by modification of pulp fibers with xylanases is an attractive approach to reduce the consumption of toxic bleaching chemicals in the paper industry. In this study, an alkaliphilic endoxylanase gene was isolated from metagenomic DNA of a structurally stable thermophilic lignocellulose-degrading microbial consortium using amplification with conserved glycosyl hydrolase family 10 primers and subsequent genome walking. The full-length xylanase showed 78% sequence identity to an endo-${\beta}$-1,4-xylanase of Clostridium phytofermentans and was expressed in a mature form with an N-terminal His6 tag fusion in Escherichia coli. The recombinant xylanase Xyn3F was thermotolerant and alkaliphilic, working optimally at $65-70^{\circ}C$ with an optimal pH at 9-10 and retaining >80% activity at pH 9, $60^{\circ}C$ for 1 h. Xyn3F showed a $V_{max}$ of 2,327 IU/mg and $K_m$ of 3.5 mg/ml on birchwood xylan. Pre-bleaching of industrial eucalyptus pulp with no prior pH adjustment (pH 9) using Xyn3F at 50 IU/g dried pulp led to 4.5-5.1% increase in final pulp brightness and 90.4-102.4% increase in whiteness after a single-step hypochlorite bleaching over the untreated pulp, which allowed at least 20% decrease in hypochlorite consumption to achieve the same final bleaching indices. The alkaliphilic xylanase is promising for application in an environmentally friendly bleaching step of kraft and soda pulps with no requirement for pH adjustment, leading to improved economic feasibility of the process.