• 펄프종이기술
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• 제29권3호
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• pp.43-50
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• 1997

The purpose of this study was to decrease pollutants of effluents from KP bleaching. Multistage bleaching that combined with O, Eo, and C/D stage was conducted, after optimum bleaching conditions of O, Eo, and C/D stage were determined. Moreover the properties for bleached pulps and pollution level of bleaching effluent were measured by each standard method. Due to increase on the brightness and delignification of pulps by O, Eo, and C/D stage bleaching. It was possible that bleaching sequences were reduced from five stage to four stage. In addition to, OC/DEoD and OC/DEopD bleaching sequences had higher brightness than CEDED bleaching sequence. The pulps bleached by O and Eo stage had higher in tensile index than conventional bleaching sequences with the similar results in burst and tear index. While each bleaching sequences had little differences, bleaching sequences with Eo stage had higher in physical properties than with Eop stage. The pollution level measured by Chemical Oxygen Demand(COD), Biochemical Oxygen Demand(BOD) and Color of bleaching effluents were much lower in combined bleaching sequences of O, Eo and C/D stage than that of CEDED sequence. Particularly, a pollution index of bleaching effluents generated by C/DEoDEB and OC/DEopDED bleaching sequences were lower than that from the other bleaching sequences.

• 펄프종이기술
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• 제33권3호
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• pp.84-99
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• 2001

This study was carried out to acquire basic data necessary for the use of rice-straw chemical pulp. It investigated the proper bleaching conditions when rice-straw chemical pulp(alkaline sulfite-${Na_2}{S_2}{O_4}$) was bleached using the various kinds of bleaching agents by the two-stages bleaching methods. And, physical properties of pulps bleached with eight kinds of two-stages bleaching methods were tested. The results of this study were as follow; 1. The first-stage bleaching was conducted under the proper conditions with chlorine(C). And then, the proper conditions related to the calcium chlorite(H), hydrogen peroxide(P) and sodium hydrosulfite(Y) bleaching as the second-stage bleaching were investigated. The proper conditions of CH stage were determined to be 0.3% concentration of calcium chlorite, $30^{\circ}C$ of reaction temperature and 20min. of reaction time. For CP stage, the proper conditions of concentration of hydrogen peroxide, reaction temperature and reaction time were 1.5%, $60^{\circ}C$ and 90min., respectively. And for CY stage, the proper conditions were 0.5% concentration of sodium hydrosulfite, $40^{\circ}C$ of reaction temperature and 90min. of reaction time. 2. The first-stage bleaching was conducted under the proper conditions with chlorine dioxide(D). And then, the proper conditions related to the calcium chlorite(H), hydrogen peroxide(P) and sodium hydrosulfite(Y) bleaching as the second-stage bleaching were investigated. The proper conditions of DH stage were determined to be 0.5% concentration of calcium chlorite, $25^{\circ}C$ of reaction temperature and 5min. of reaction time. For DP stage, the proper conditions of concentration of hydrogen peroxide, reaction temperature and reaction time were 1.0%, $70^{\circ}C$ and 90min., respectively. And for DY stage, the proper conditions were 0.3% concentration of sodium hydrosulfite, $50^{\circ}C$ of reaction temperature and 20min. of reaction time. 3. The first-stage bleaching was conducted under the proper conditions with calcium chlorite(H). kAnd then, the proper conditions related to the hydrogen peroxide(P) and sodium hydrosulfite(Y) bleaching as the second-stage bleaching were investigated. The proper conditions of HP stage were determined to be 0.3% concentration of hydrogen peroxide, $30^{\circ}C$ of reaction temperature and 60min. of reaction time. For HY stage, the proper conditions of concentration of sodium hydrosulfite, reaction temperature and reaction time were 2.5%, $60^{\circ}C$ and 30min., respectively. 4. When the rice-straw chemical pulps were bleached with eight kinds of two-stages bleaching methods in the proper conditions mentioned above, respectively, the final brightnesses after CH, CP, CY, DH, DP, DY, HP, and HY bleachings were 62.0, 74.3, 61.4, 58.9, 66.9, 62.9, 50.4 and 60.1, respectively. And strengthes of pulps bleached with DP and DH methods were comparatively higher than those of pulps bleached with other bleaching methods.

• 펄프종이기술
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• 제29권2호
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• pp.36-45
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• 1997

Newly bleaching sequence using oxygen, ozone and hydrogen peroxide has introduced to avoid pollution hazards from chlorinated organic compounds, because chlorine dioxide substitution bleaching was produced a little chlorinated organic substance. Oxygen-type chemicals replaced for chlorine has attracted much research attention. Bleachability of ozone was improved at low temperature and high pulp consistency. In third bleaching followed OZ bleaching, addition of O2 and NaBH4 in alkali extraction was effective than only alkali extraction. Bleachability of pulps in ozone bleaching(Z) was improved at higher consistency and lower temperature The addition O2 and NaBH4 in alkali extraction after OZ bleaching sequence improved brightness, when compared to those obtained by only alkaline extraction. Pulps bleached by ECF bleaching sequences such as OZEoD and OZEopD was obtained by 90% ISO brightness. The brightness of pulp bleached by TCF sequences with the ozone dosage of 1.6% was approached to target brightness (88~90%ISO). Pulps bleached Z stage combined bleaching sequence was reduced the viscosity to a little greater extent. However, physical properties of pulps was not great different compared to those bleached by conventional bleaching sequences. A pollution index of bleaching effluente by ozone combined bleaching sequences was lower than by conventional bleaching sequence, but somewhat higher than multistage bleaching sequences combined C/D stage.

• 펄프종이기술
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• 제36권1호
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• pp.37-42
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• 2004

ECF and TCF bleaching methods are favored in bleaching plants over the world due to the increasing environment constraints. However, interaction of main stages(D and O stage) in ECF bleaching have not been understood completely yet. The degradation of holocellulose as a carbohydrate model compound was investigated by SEC(size exclusive chromatography) to estimate the change of its molecular weight distribution after O and D stage combination treatment. The molecular weight distribution of holocellulose was observed in two divisions(higher and lower molecular portions). It was also shown that DO sequence was more effective than OD, and DOD or ODO was more effective than DO. D stage had a little effect on the degradation of holocellulose, while the degradation of holocellulose increased as the time of the first O stage increased.

• 펄프종이기술
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• 제46권1호
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• pp.1-10
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• 2014

Xylanase (X) derived from Aurreobasidium pullulans and laccase-mediator system (LM) using Trichophyton sp. LKY-7 laccase (TrL) and N-hydroxy-2-pyridone analogue (NHP) as a mediator were applied in hardwood kraft pulp (HwKP) bleaching. The individual and the synergistic effects of X and LM stage were investigated in the enzymatic bleaching of HwKP. Also, the effects of subsequent alkaline extraction (E) and alkaline/hydrogen peroxide treatment (P) were examined. In X or LM treatment alone, an appreciable bleaching effect of HwKP was not observed, whereas subsequent E or P stage enhanced the increase of brightness and the decrease of kappa number. Especially, P stage significantly enhanced the bleaching effect of pulp. Bleaching of HwKP with XLM sequentially gave significantly higher pulp brightness and lower kappa number than that obtained after the treatment of HwKP with X+LM simultaneously. When HwKP was sequentially treated with XLM followed by P stage, the brightness increased by about 11% ISO and the kappa number decreased by about 3.6 in comparison with the initial pulp. Xylanase and laccase were strongly inactivated by NHP both in the absence and the presence of pulp.

• 분석과학
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• 제14권3호
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• pp.266-273
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• 2001

염소표백공정을 포함하고 있는 펄프 제지폐수 배출시설의 폐수 중 다이옥신류의 배출 특성 및 형성 메카니즘을 규명하기 위해 표백공정 전 후단에서 배출되는 산성 원폐수를 채취 분석하였다. 표백공정 전단 및 후단에서 배출되는 퓨란류(PCDFs)와 다이옥신류(PCDDs)는 약 2:3의 비율로 배출되었으며, 표백공정 전당에 비해 후단에서는 1,2,3,7,8 - 오염화다이옥신(PeCDD)을 제외한 2,3,7,8-치환이성체들의 배출농도가 증가된 것으로 조사되었다. 특히, 2,3,7,8-사염화퓨란(TCDF)은 0.0322ng/L에서 0.1580ng/L 약 5배, 팔염화다이옥신(OCDD)은 0.0794ng/L에서 0.5745ng/L로 7배 배출농도가 증가된 것으로 조사되었으며, 표백공정중 이들 이성체가 주로 형성 배출되어 전형적인 펄프 제지 제조시설의 다이옥신 배출패턴을 나타내고 있는 것으로 나타났다.

• 펄프종이기술
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• 제29권1호
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• pp.52-61
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• 1997

This study was aimed to decrease AOX(Adsorbed Organic Halide Compounds) by applying bleaching methods of A(HNO$_3$ ＋ NaNO$_2$) and $D^{(H/L)}$(dual pH chlorine dioxide bleaching) to conventional OCEDED bleaching stages. And so we investigate the effects of NSA treatment and the influence of production rate of ion species in chlorine dioxide and pulp mixtures according to various pH as well as dual pH on pulp bleaching. Finally the effects of AOC_DED^{(H/L)}ED^{(H/L)}$ bleaching stage were investigated by measuring AOX, brightness, kappa number and viscosity of pulps. A stage was treated by using 4% $HNO_3$ and 0.05~2.0% $NaNO_2$ on pulp and $D^{(H/L)}$ stage was like that pulp mixed with chlorine dioxide solution was adjusted at pH 7.0 and reacted in pulp cosistency 3%, S~20min, $70^{\circ}C$, and then successively for 160~175min at pH 4.0. It was found that suitable $NaNO_2$ addition rate was at 0.6% where the brigtness of pulp was most higher and pulp viscosity was not decreased much. Chlorate ($CIO_3$) was decreased according to pH increase but chlorite($CIO_2$) was highly decreased according to pH increase. And chloride was slightly increased with pH increase. The applying of A and D^{(H/L)}$ bleaching stages to some various multiple bleaching stages ($AOC_DED^{(H/L)}/EopD^{(H/L)} etc.$) had good results that brightness was increased more 2~3% ISO than conventional method(OCEDEopD), but viscosity was dropped by only 1~2cps.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.2
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• pp.381-386
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• 2006

Many different types of bleaching chemicals and processes have been globally used for deinked pulp. Besides chlorine-free bleaching chemicals, hydrogen peroxide, and sodium dithionite that could be used without restriction for almost all types of fibers, chlorine-containing chemicals such as chlorine dioxide and sodium hypochlorite have also used throughout the world. Even though hydrogen peroxide is commonly used in newsprint, it could not effectively increase brightness. Experimental evaluation on the possibility of using formamidine sulfinic acid (FAS), a reducing agent, for bleaching a wood-containing deinked pulp has been carried out in this study. The effect of bleaching efficiency for FAS on operational conditions and chemical concentrations compaired to hydrogen peroxide in one and two stages was studied. FAS bleaching showed higher brightness at high temperature and low consistency, and vice versa for peroxide one. Bleaching with sodium silicate and DTPA in FAS and peroxide stage showed better results than cases without them. Sodium silicate and chelant seemed minimize the influence of transition metal ions, including manganese and iron ions, which induce both bleaching agents to decompose. As a result, FAS as a reducing agent seems more effective than hydrogen peroxide for increasing brightness and reducing yellowness. FAS and FAS sequence seemed more efficient than the other two stages of bleaching sequences with regard to the best brightness level obtained. When bleaching was conducted with FAS, COD load was just about one-third compared to peroxide, and brightness stability of the bleached pulp appeared better than peroxide after UV light irradiation.

• 펄프종이기술
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• 제31권5호
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• pp.86-94
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• 1999

Alkaline peroxide bleaching of chemi-mechanical pulp is a very complicated system where various process factors affect the bleacing performance and pulp properties. Traditional onefactor-at a time method is ineffective and costly infinding the optimal bleaching conditions. In this study, statistical experimental design and multiple regression method wre used to investigated the interactions among various bleaching factors and to find out the possbile maximal brightness development during one stage alkaline peroxide bleacing of TMP. The TMP was made from 10% Korean red pine and 90% Korean spruce and had an initial brightness of 54.5% ISO. the TMP was pretreated with EDTA(0.5% on O.D. pulp, 3% pulp consistency, 30$^{\circ}C$ for 60 minutes) and bleached in a 2 L Mark V Quantum Reactor at 750 rmp, 7.5% of bleaching consistency and with 0.05% magnesium sulfate addition. The ranges of chemical factors studied , based on oven-ried pulp, were 1-5% for hydrogen peroxide, 1-4% for sodium hydroxide and 1-4% for sodium silicate. The rages of reaction temperature and time were 50-90$^{\circ}C$ and 40-180minutes respectively. Interactions of hydrogen peroxide with alkali , time with temperature ature, alkali with time and silicate with temperature were found to be significant which means that hydrogen peroxide bleaching will be favored at stable concentration of perhydroxyl ion, relatively short time and low temperature, and high level of silicate. Mathematical model which has good predictability for target brightness in one stage peroxide bleaching can also be established easily. Base ion the model, maximal brightness of 70% ISO was found to at 50$^{\circ}C$ and 50 minutes by chemical additions of 5% for hydrogen peroxide, 3.2-3.4% for sodium hydroxide and 4% for silicate based on O.D. pulp. However, this result might not be suitable for situation where furnishes are different from ours, or different pretreatment is used, or bleaching carried out at different pulp consistency. In these cases it will be good to re-investigate the process by a similar methodology as was used in this study.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 1999년도 추계학술발표논문집
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• pp.180-186
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• 1999

Alkaline peroxide bleaching of (chemi) mechanical pulp is a very complicated system where various process factors affect the bleaching performance and pulp properties. Traditional on-factor-at a time method is ineffective and costly in finding the optimal bleaching conditions. In this study statistical experimental methods which include three steps. I. e. screening, response surface modeling and optimization, were used to find the conditions for maximal brightness development during one stage alkaline peroxide bleaching of TMP which had an initial brightness of 54.5% Elerpho. The TMP was pretreated with EDTA(0.5% on O. D. pulp. consistency, $30^{\circ}C$ for 60 minutes) and bleached in a 2L Mark V Quantum Reactor at 750rpm, 7.5% of bleaching consistency and with 0.05% magnesium sulfate addition. The ranges of other factors studied were 1~5% hydrogen peroxide on O. D plup, 1~4% sodium hydroxide on O. D pulp and 1~4% sodium silicate on O. D pulp, reaction temperature 50~$90^{\circ}C$ and reaction time 40~180minutes. A models with good predictability was established and the maximal brightness after one stage bleaching was found to be 70% Elerpho at $50^{\circ}C$, 50 minutes 5% hydrogen peroxide on O. D. pulp 3.2~3.4% sodium hydroxide on O. D. pulp 3.2~3.4% sodium hydroxide on O. D pulp and 4% silicate on O. D pulp. However further studies on other pulp properties such as strength and brightness stability shall be carried out in order to find out the optimal bleaching conditions.