• Proceedings of the Membrane Society of Korea Conference
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• 1997.06a
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• pp.93-104
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• 1997

The objective of this study is to develop a method to reduce arsenic concentrations in contaminated water. This work is also aimed at increasing the specificity of membrane separation processes. Arsenic in contaminated waters is often present in the form of negatively charged oxyanions. These are relatively small molecules which cannot be separated directly by ultrafiltration. Oxyanions can be captured by polyelectrolytes and separated by ultrafiltration. Results will be presented on the use of two polyelectrolytes; polyethylenimine (PEI) and poly-diallyl dimethyl ammonium chloride (DADMAC) at various feed concentrations. A semi-continuous process utilizing PEI in a circulation loop was tested. The restfits indicate that better than 99.6 % recovery (permeate concentration < 0.001 $\mu$g/L) can be achieved based on an initial arsenic concentration of 300 $\mu$g/L. The results indicate that this treatment method is suitable as a main treatment process for drinking water or a polishing step after arsenic precipitation.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.11
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• pp.729-734
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• 2012

During chlorination processes dissolved organic nitrogen (DON) can form toxic nitrogenous disinfection byproducts and organic chloramines which have little or no bactericidal activity. DON needs to be removed before chlorination processes to reduce the formation of those products. This study investigated the removal of DON from surface water and reclaimed water by coagulation with aluminum sulfate (alum) and a cationic polymer (polyDADMAC). Removal characteristics of dissolved organic carbon (DOC) and ultraviolet absorbance at 254 nm ($UVA_{254}$) were compared with that of DON. Coagulation with alum removed DON, DOC, and $UVA_{254}$ with similar trends, but the removal of $UVA_{254}$ was highest. A dual coagulation strategy of alum and cationic polymer improved the removal of DON. Coagulation with cationic polymer alone was not effective due to its narrow range of charge neutralization. DON in reclaimed water was easier to remove than that in surface water, and higher molecular weight fraction (>10,000 Da) of DON was preferentially removed.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.43 no.5
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• pp.60-67
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• 2011

Hemicelluloses pre-extracted from Korean mixed wood chip were investigated as a wet-end additive. Hemicelluloses dissolved in hot water and alkali solution were isolated by ethyl alcohol precipitation from pre-extractives. They showed molecular weight of 9,000 ~ 27,000 g/mol as revealed by size exclusion chromatography. The reduction of molecular weight through hot water extraction was caused by autohydrolysis. Chemical composition of the hemicelluloses were analyzed with high-performance liquid chromatography and UV-Vis spectroscopy. As the surface charge of isolated hemicelluloses were negative, the adsorption of hemicelluloses onto softwood unbleached kraft pulp fiber was promoted by poly-DADMAC. The physical properties of handsheets increased as the molecular weight of hemicellulose increased. On the other hands, the optical property decreased with hemicellulose adsorption.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.35 no.3
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• pp.21-28
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• 2003

It is essential to use base papers having proper surface characteristics in coating operation for improving coated paper quality and coater runnability. To fulfill these purposes surface sizing of coating base stock with anionic oxidized starch is commonly practiced. It is suggested that use of cationic starch for surface sizing rather than conventional oxidized starch will improve coated paper quality since cationic starch penetrates less into paper structure because of its strong electrostatic interaction with anionically charged paper surface. Strong interaction of cationic surface sizing starch with anionic coating color is expected to promote rapid immobilization of the coating color and improve coating holdout and optical property. The immediate objective of this study was to examine the influence of surface sizing starches on the properties of coated papers. Structural characteristics of the coatings formed on the substrate surface sized with cationic and anionic starches were examined. To enhance the efficiency of cationic surface sizing starch on coated paper properties, strongly charged cationic polymers were added to the surface sizing starch and its effect on coated paper properties was evaluated. Results showed that opacity and light scattering coefficient of coated paper were higher when base paper surface sized with cationic starch was used. Addition of less than 1% of cationic poly-DADMAC to the cationic surface sizing starch improved the opacity of coated paper significantly.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.4
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• pp.71-77
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• 2010

To utilize modified pulp fibers in papermaking system, it is necessary to evaluate the interaction between modified fibers and papermaking additives. Fluorescent whitening agent (FWA) is an important additive which has been widely used for production of writing and printing paper. We modified pulp fiber surface by Layer-by-Layer multilayering of polyelectrolytes, and investigated the interaction between these fibers and FWA used in internal addition or surface treatment. Pulp fiber with cationic surface charge showed a good affinity to internal FWA. For FWA in surface sizing agent, whiteness and brightness of paper was dependent on pickup weight and polyelectrolyte type. Pulp fibers with C-starch/PSS multilayer showed better optical properties than poly-DADMAC/PSS treatment. It indicated that polyelectrolyte type in Layer-by-Layer multilayering as well as a good affinity to FWA is important to get better whiteness and brightness.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.4
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• pp.53-60
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• 2007

LbL multilayering technology introduced by Decher is a nano technique that a substrate surface is layered by the successive deposition of polyelectrolytes with positive and negative charge. We investigated the electrochemical properties of LbL multilayered pulp fibers with poly-DADMAC and PSS. Three types of pulp-Hw-BKP, BCTMP and KOCC- were treated with polyelectrolytes. Zeta potentials of multilayered fibers ranged from +30 mV to +40 mV, depending on the intial zeta potential of pulp fibers and fines content. All kinds of pulp which were examined in this study, however, showed a similar zeta potential of -35 mV after layering with PSS. To obtain pulp fiber with a uniform and stable zeta potential, BCTMP and KOCC pulp fibers should be multilayered above 5 times. The addition level of polyelectrolytes had little influence on the zeta potential of pulp fibers.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.3
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• pp.15-22
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• 2008

Properties of pulp fibers can be modified by LbL multilayering technology. We evaluated the effect of stock composition on the polyelectrolyte multilayering performance of pulp fibers in this study. Stock composition was varied with pulp type and fines content. Three types of pulp-Hw-BKP, BCTMP and KOCC-were treated with polyelectrolytes of poly-DADMAC and PSS. Fines content of stock were controlled at 0, 10, 20, 30, and 40%. Zeta potential of pulp fibers and charge demand of filtrate were evaluated. The highest adsorption ratio was obtained for BCTMP because of its shortest fiber length and highest specific surface area. Higher fines content in the stock increased the adsorption ratio of polyelectrolyte onto pulp fiber and it required a higher amount of polyelectrolyte for charge neutralization. For the pulp stock with higher fines content, a higher level of polyelectrolyte and the increased layer number were required to modify and stabilize the electrochemical properties of pulp fibers.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.44 no.5
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• pp.8-13
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• 2012

The flexography ink has disadvantage in a deinking process because it tends to form too fine particles in alkali condition to be removed in flotation deinking. The influence of pH conditions on the particle size of phthalocyanine cyan ink used for flexo-printing was investigated to see the effect of pH conditions on flexography ink dispersion. Flexography ink particles prepared by grinding dried ink films were used in this experiment. Greater reduction of the ink particle size was noticed under alkaline pH condition, which was attributed to dissolution of resin component of the ink. Adsorption behavior of flexography ink onto pigment particles was examined using clay and talc as substrate pigments. Pretreatment of inorganic pigments with a cationic poly-DADMAC increased the surface adsorption of flexography ink particles, which improved the removal of the inks by centrifugal sedimentation of inorganic pigments. Most efficient removal of the ink particles was achieved when an optimal addition level of the cationic polymer was used for pretreatment of inorganic pigments, and this optimal addition level corresponds to the surface saturation point of the polyelectrolyte. Adsorption of flexography ink particles onto inorganic pigments improved the ink removal in flotation deinking since the pigment particles has the optimal particle size for flotation deinking.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.4
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• pp.201-207
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• 2017

This study was conducted to investigate the characteristics of the stream current detector (SCD) and charge analyzing system (CAS), which are well known as the automatic coagulant dosage determination instruments. When the SCD system was used, the current charge value set at pH 9.3 could not be used as the coagulant dosage when the pH of the raw water decreased to 5.7, and the current charge value corresponding to pH 5.7 was required to be reset. In case of CAS system, polydadmac is stable as a cationic titrant when the pH of the raw water ranged 9.3 to 6.0. And it was effective to use polydadmac as a cationic titrant for high turbidity water. The current charge of polydadmac was almost constant between pH 5 and 11, however, the difference in charge of alum is six times in this pH range. Therefore, when the pH of the raw water was changed, it seems that the coagulant used in the actual water treatment plant was as a good cationic titrant.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2002.05a
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• pp.108-108
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• 2002

고분자전해질들은 제지공정에서 건조지력제, 습윤지력제, 정착제, 보류제 등으로 널리 사 용되어지고 있으며, 이러한 고분자전해질들이 보유하고 있는 관능기의 종류와 분자량에 따라 각각의 다른 특성을 발현하게 된다. 이중 관능기의 종류와 비율에 따라 결정되는 중요한 특성 중 한가지가 전하밀도이며, 이러한 전하밀도는 제지공정에 사용할 때 습부공정에서 매우 중요 한 인자라 할 수 있다. 전하밀도는 고분자전해질의 분자구조와 단량체의 종류에 따라 다르며, 적용 pH의 조건에 따라 변화하게 된다. 3급 아민과 4급 암모늄을 관능기로 가진 고분자전해질 의 경우 pH에 따른 전하밀도의 변화는 이미 잘 알려져 있는 바,3급 아민을 작용기로 가진 양이 온성 고분자전해질은 pH 9에 도달하면 양전하를 완전히 상실하고,4급 암모늄을 작용기로 가진 양이온성 고분자전해질은 pH의 변화에 상관없이 양전하가 변하지 않는다고 보고되어 있다. 본 연구에서는 양이온성과, 양쪽이온성 고분자전해질들 중 Cationic PAM, Amphoteric P PAM, PolyDADMAC, Epoxide polyamide resin, Epi-DMA copolymer 등을 시 료로 사용하였 으며, 양이온성 관능기의 종류가 다른 고분자 전해질을 이용하여 pH 변화에 따른 전하밀도의 변화를 검토하였다. 또한 일반적으로 중성 초지공정의 pH 조건은 7.0 - 8.0이며, 이 pH 조건에 서 고분자전해질의 거동은 매우 중요하다고 할 수 있다. 따라서 양이온 관능기의 종류에 따른 고분자전해질들을 pH 7.8에서 보관시간에 따른 전하밀도의 변화를 조사하였으며, 전하밀도가 변화하는 양상에 따라 양이온성 관능기의 분자구조의 변화를 검토하였다. p pH 변화에 따른 전하밀도의 변화 결과로부터 3급 아민을 포함한 양이온성 고분자전해질 뿐만 아니라,4급 암모늄을 포함한 일부의 양이온성 고분자전해질 또한 알카리 조건에서 전하 밀도가 감소하며, 강한 얄차리 조건에서는 음이온성 고분자전해질로 변화하는 현상을 관찰할 수 있었다. 이상의 결과들로부터 약 알카리(pH 7.5 - 8.0) 조건 하에서도 시간의 변화에 따라 4 급 암모늄을 포함하는 고분자전해질의 전하밀도가 변화할 것이라 예측하였으며, 실험을 통해 그 사실을 확인하였다. 알카리 조건에서 전하밀도가 변하지 않는 4급 암모늄 고분자전해질과, 전하밀도가 변하는 4급 암모늄 고분자전해질의 분자구조를 비교해 볼 때, 그 원인은 4급 암모늄 의 관능기가 고분자 연쇄로부터 가수분해 되어 나타나는 현상으로 판단된다.