• Membrane and Water Treatment
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• v.7 no.5
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• pp.417-431
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• 2016

Poly(vinylidene fluoride) (PVDF) powder was treated with aqueous sodium hydroxide to obtain partially defluorinated fluoropolymers with expected properties such as improving hydrophilicity and fouling resistance. Raman spectrum and FT-IR results confirmed the existence of conjugated carbon double bonds after alkaline treatment. As the concentration increased, the degree of defluorination increased. The morphology and structure of membranes were examined. The permeation performance was investigated. The results showed that membrane's hydrophilicity increased with increase of the percentage of alkaline treated PVDF powder. Moreover, in terms of the water contact angle, it decreased from $92^{\circ}$ to a minimum of $68^{\circ}$; while water up take increased from 128 to 138%. Fluxof pure water and the cleaning efficiency increased with the increase of alkaline treated PVDF powder. The fouling potential also decreased with the increase of the percentage of alkaline treated PVDF powder. The reason that makes blending PVDF show different characteristics because of partial defluorination, which led the formation of conjugated C = C bonds and the inclusion of oxygen functionalities. The polyene structure followed by hydroxide attack to yield hydroxyl and carbonyl groups. Therefore, the hydrophilicity of blending membrane was improved. The SEM and porosity measurements showed that no obvious variations of the pore dimensions and structures for blend membranes were observed. Mechanical tests suggest that the high content of the alkaline treated PVDF result in membranes with less tolerance of tensile stress and higher brittleness. TGA results exhibited that the blend of alkaline treated PVDF did not change membrane thermal stability.

• Journal of the Korean Wood Science and Technology
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• v.29 no.4
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• pp.67-78
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• 2001

Two species(Quercus mongolica, populus euramericana) of hardwood chips were subjected to steam explosion 25 kg/$cm^2$, for 6 min. The exploded woods were treated by the single or multi-stage chemical process with sodium hydroxide, sodium hypochlorite and sodium chlorite. The multi-stage treatment of exploded wood can be successfully removed lignin. Enzymatic hydrolysis rate of substrate varied from 25% for exploded wood to about 80% for the multi-chemical treated exploded wood. The enzymatic susceptibility was different among wood species. The multi chemical treatment of the exploded wood resulted in the high rate of glucose in the enzymatic hydrolyzate. Cellulase adsorption increased at high lignin content of substrates, while crystallinity, pore area and specific surface area of substrates did not affected enzyme adsorption. According to the proposed pretreatment and saccharification process in this study, it can be acquired about 37~40 kg of glucose from 100 kg of hardwood.

• Journal of Dairy Science and Biotechnology
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• v.41 no.4
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• pp.203-210
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• 2023

Bacterial contamination negatively affects the quality, functionality, and safety of dairy products. Adherent populations of bacteria, referred to as biofilms, grow on the surfaces of dairy processing equipment and are the primary cause of dairy contamination. In addition, microorganisms present in the farm environment and dairy factory can contaminate the Clear-In-Place (CIP) line through raw milk transport pipes; therefore, exhaustive management is required. In dairy manufacturing facilities, biofilm formation is controlled using CIP systems that primarily require sodium hydroxide and nitric acid. However, the leakage or incomplete removal of these potently active compounds can be harmful to humans. In the present study, we compared the eradication of Escherichia coli and other bacteria using commercially available combinations of sodium hypochlorite (NaClO) and citric acid, which are recognized by the Korean Ministry of Food and Drug Safety (MFDS) as food disinfectants. When considered in the CIP system of the field manufacturing process, E. coli was not detected (compared to detection before treatment), and other bacteria were detected at 0-32 culture-forming units (CFU)/cm². The residual amount of chlorine ions after CIP treatment was similar to that in tap water, and there was no significant difference in the overall components of the fermented dairy products. Therefore, the NaClO/citric acid CIP system can be safely applied in dairy manufacturing processes.

• Advances in environmental research
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• v.6 no.2
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• pp.147-158
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• 2017

This paper represents a set of experimental tests on remediation of nickel-contaminated kaolin by Electrokinetic method. For this purpose, we conducted unenhanced and EDTA-enhanced Electrokinetic tests in one, three, and five days of treatment. In unenhanced tests, we used deionized water as an electrolyte in the anode and the cathode compartments. In the EDTA-enhance tests, we used ethylenediaaminetetra acetic acid 0.1 Molar in the cathode and sodium hydroxide 0.1 Molar in the anode. The average nickel removal for unenhanced tests after three and five days of treatment was 19 and 23 percent, respectively. High buffer capacity of the soil is responsible for low removal efficiency in the unenhanced tests, which maintained pH close to the initial amount that restrained nickel as an adsorbed or precipitated forms. The average nickel removal for EDTA-unenhanced tests after three and five days of treatment was 22 and 12 percent, respectively. Lower ionic mobility of EDTA-Ni complex in comparison with $Ni^{+2}$, which is the main transportation mechanism for this complex, could be responsible for less removal efficiency in EDTA-enhanced test.

• Food Science and Preservation
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• v.17 no.1
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• pp.91-99
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• 2010

Extraction and bleaching of citric acid- and pepsin-soluble collagens (ASC and PSC, respectively) from shark (Isurus oxyrinchus) skin and muscle were investigated. The optimal sodium hydroxide concentration for extraction was 0.3 M and the optimal treatment time for removal of foreign material was 9 h. The optimal sodium hypochlorite level for bleaching of shark skin was 0.48% (w/v), and sodium hypochlorite was a better bleaching agent than acetone, hydrogen peroxide (10%, v/v), sodium sulfite (0.48%, w/v), sodium thiosulfate (0.48%, w/v), or sodium metabisulfite (0.48%, w/v). Optimal citric acid concentration and extraction time for ASC were 0.3 M and 72 h, respectively, whereas optimal conditions for extraction of PSC were treatment with 0.1 M citric acid containing 0.1% (w/v) pepsin for 24 h. Protein contents in ASSC (acid-soluble shark skin collagen), ASMC (acid-soluble shark meat collagen), PSSC (pepsin-soluble shark skin collagen), and PSMC (pepsin-soluble shark meat collagen) were 88.66%, 83.09%, 90.33%, and 84.81% (on a dry weight basis), respectively, similar to that of commercial marine collagen (88.86%). Net collagen contents of ASSC, ASMC, PSSC, and PSMC, calculated from hydroxyproline levels, were 70.31%, 25.70%, 83.09%, and 32.94%, respectively. The yields of freeze-dried ASSC, ASMC, PSSC,and PSMC were 57.22%, 53.85%, 23.28%, and 20.61%.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.32.1-32.1
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• 2009

현재 ITO를 대체할 재료로 투명 전도성 탄소나노튜브(carbon nanotube, CNT) 필름에 대한 연구가 진행 되고 있다. 이러한 연구에서 특히 CNT 필름의 투과도에 따른 전기저항을 향상시키기 위한 연구가 활발히 진행되고 있다. 본 연구에서는 단일벽 CNT (single-walled CNT)를 여러 가지 계면활성제로 최적 분산시킨 수용액으로부터 제조한 CNT 필름의 투과도에 따른 면 저항 (sheet resistance) 변화를 관찰하였다. 우선 계면활성제로 분산시킨 CNT 수용액을 알루미나 재질의 필터에서 정량적으로 진공 필터링하여 CNT 필름을 제조하였다. 알루미나 필터를 sodium hydroxide (NaOH) 수용액으로 용해시켜 제거함으로써 얻은 CNT 필름을 유리기판 위에 부착시켰다. 필름의 전기저항을 낮추기 위해 유리기판 위에 부착된 CNT 필름을 질산 (HNO3) 용액으로 처리하였다. Scanning electron microscopy, UV-Vis spectroscopy를 이용하여 각각 필름의 형상과 광 투과도를 분석하였고, 4-point probe로 면 저항을 측정하였다. 계면활성제로 분산시킨 CNT 필름 대부분의 면 저항은 질산 처리에 의해 감소하였다. 이는 CNT 표면에 코팅되어 있던 계면활성제가 질산에 의해 제거되었기 때문인 것으로 예상된다. 여러 계면활성제 중 sodium dodecyl benzenesulfonate로 분산시킨 CNT 필름이 산 처리 후에 가장 낮은 면 저항을 보였다. 그리고 Polyvinyl pyrrolidone (PVP)과 cetyltrimethylammonium bromide (CTAB)를 사용하여 제조한 CNT 필름의 면 저항이 가장 뚜렷한 감소를 보였다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.1
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• pp.15-21
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• 2023

To prepare zinc oxide powder, three types of sodium-based alkali precipitants such as NaOH, Na₂CO₃, NaOH/NaHCO₃ were compared to the differences in the manufacturing process of zinc oxide powder from zinc precipitate products like intermediates with the consideration of thermodynamic reaction. The prepared zinc precipitate products by the reaction with the sodium-based alkali precipitant were confirmed to respectively hydroxy zinc chloride (Zn₅(OH)₈Cl₂·H₂O) and zinc carbonate hydroxide (Zn₅(OH)₆(CO₃)₂·H₂O) from XRD analysis. Zinc oxide particles were compared in heat treatment at 800℃ according to sodium-based alkali precipitants. The mixed NaOH and NaHCO₃ of alkali precipitant reaction was contributed to synthesize the more uniform zinc oxide particles.

• Korean Journal of Food Science and Technology
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• v.7 no.3
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• pp.115-119
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• 1975

Imported seaweeds Gracilaria sp. and Gelidium sp. from the Philippines and Gracilaria sp. from Brazil were subjected to the examination of yield and quality of agar according to various pretreatment conditions. As pretreatment condition for alkali-treated Gracilaria sp. from the Philippines, $0.05{\sim}0.1%$ concentration of sulfuric acid was proper to obtain the higher yield of agar for which a reverse proportionality was shown between the acid concentration and the strength of extraction condition. Highest yield from Gelidium sp. from the Philippines was obtained by pretreating with 5% sodium hydroxide at $90^{\circ}C$ for one hour, followed by 0.1% sulfuric acid treatment. Gracilaria sp. from Brazil gave the highest yield of agar by pretreatments with 1% sodium hydroxide followed by 0.05% sulfuric acid, both at room temperature for one hour. Acid treatment of alkali-treated Gracilaria sp. from the Philippines brought about the decrease of total nitrogen, total sulfur and crude ash, the increase of jelly strength and no marked change in gelation point and gelation ability. In general, acid-treatment conditions to give rise to high yield of agar improved the quality of product.

• Journal of Environmental Science International
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• v.17 no.5
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• pp.565-571
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• 2008

The surface properties of activated carbon modified by acids and base were studied. The influence of the surface chemistry on the adsorption of benzene and acetone vapor on modified activated carbons has been investigated The modified activated carbons were obtained by treatment with acetic acid ($CH_3COOH$), nitric acid ($HNO_3$) and sodium hydroxide (NaOH). The modified activated carbons had similar porosity but different surface chemistry and adsorption characteristics. The total surface acidity (sum of functional groups) of activated carbon (AC-AN) treated by nitric acid was 2.6 times larger than that of activated carbon (AC) before the acid treatment. Especially, carboxyl group was much developed by nitric acid treatment. The benzene equilibrium adsorption capacity of AC-AN decreased 20% more than that of AC. However, the acetone equilibrium adsorption capacity of AC-AN increased 20% more than that of AC because of the large increase of carboxyl group and acidity.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10a
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• pp.83-84
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• 2003

The microstructure and tensile properties of ramie treated with NaOH and crosslinked with 1, 2, 3, 4-butanetetracarboxylic acid were characterised. X-ray diffraction and FTIR were used to study the crystalline structure o f the resultant ramie yarns. Results showed that the maximum change in the structure of the modified ramie took place at 16% NaOH, which would completely transform Cellulose I to Cellulose II. Also, the crystallinity index and fibre orientation decreased to the minimum value while the absorption properties were enhanced. The average degree of polymerization of the treated ramie yams slightly decreased after NaOH treatment.