• Journal of Korean Society of Environmental Engineers
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• v.30 no.12
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• pp.1273-1280
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• 2008

This study sought to establish the optimum operating condition for the recovery of caustic (NaOH) solution from mercerization in textile process. As main factors, the silt density index (SDI) evaluation of ceramic membrane for the application of nanofiltration/reverse osmosis (NF/RO) membrane, the recovery yield measurement of caustic solution for the application of polymeric membrane, the optimum condition of chemical cleaning for the membrane regeneration, the optimum removal condition of total organic carbon (TOC), turbidity, color, and the permeate flux of ceramic membrane/polymeric membrane combined process were investigated. As results, ceramic ultrafiltration (UF) in the first step and nanofiltration (NF) in the second step were found to be suitable for the removal of total suspended solid (TSS), residual organics, turbidity including color, and the recovery of caustic solution from caustic wastewater stream in mercerization process. When only the ceramic UF membrane was used, the rejection efficiency of both of TSS and turbidity was more than 99.0%, and the color and TOC were rejected about 74.7% and 49.2%, respectively. Meanwhile, the combined membrane precess of UF and NF membranes showed even more efficient removal abilities and thus more than 99.9% of TSS and turbidity, 87.7% of color, and 78.2% of TOC were removed. In particular, 91.3% of NaOH was successfully recovered with 83.7% of total volume in the combined membrane process. With this regard, a clean caustic solution was obtained in a high purity, which can be reused for mercerization process, expecting to offer economical benefits.

• Journal of the Korean Ceramic Society
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• v.24 no.2
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• pp.186-192
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• 1987

ZrO2 powders having high purity were prepared from domestic zircon sand using the caustic fusion method and the soda ash sintering process. In the caustic fusion method, ZrO2 recovery was reached to 96% when 100/140 mesh zircon was reacted with NaOH at the NaOH/Zircon mole ratio 6 and at 650$^{\circ}C$ for 2 hours. And in the soda ash sintering process, ZrO2 was recovered to 88.5% when -325 mesh zircon was reacted with Na2CO3 at the Na2CO3/Zircon mole ratio 1.1 and 1050$^{\circ}C$ for 2 hours. In both cases, Zr component was extracted to ZrOCl2, subsequently crystallized to ZrOCl2$.$8H2O to increase the purity, and converted to ZrO2 by precipitation. And to increase the sinter ability of powder, Cl- ion was removed and strong agglomeration was avoided by methanol distribution of Zr(OH)4 precipitates.

• Resources Recycling
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• v.21 no.2
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• pp.41-46
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• 2012

An investigation on the recovery of nickel from spent electroless plating solutions has been performed using the electrowinning method. For this aim, nickel in spent electroless plating solutions was separated as nickel hydroxide through the addition of caustic soda. Nickel hydroxide was completely dissolved with sulfuric acid and an electrolysis was performed for electrowinning of nickel from nickel solutions. As a result, it was found that more than 99% of nickel in spent electroless plating solutions could be precipitated as nickel hydroxide above pH 10 with the addition of caustic soda. As far as the current efficiency in electrowinning of nickel was concerned, it was decreased with increase in the current density.

• Journal of Korea Soil Environment Society
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• v.2 no.2
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• pp.73-79
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• 1997

Removal of the Arsenic components from the closed mine tailings has been attempted by the alkali-leaching method. Two tailings collected from the Daduck and Yuchon mine which were already closed many years ago were leached with caustic soda solutions. The Arsenic components in the leach liquor resulted from the alkali treatment of tailings could be removed fairly well in the form of insoluble calcium-Arsenic compound by the precipitation with calcium chloride. As a result, the extraction of about 60~90% Arsenic from the tailings could be obtained depending on the leaching conditions and the influence of temperature and the slurry density on the extraction of Arsenic was also found to be very small at the NaOH concentration more than 0.5N. In addition, it seemed that a caustic soda solution over 0.5N NaOH could be used repeatedly for the leaching of tailings since the consumption of NaOH was not so great in a leaching of them. As far as the precipitation of Arsenic components was concerned, more than 99% of Arsenic could be precipitated within 10 minutes by the addition of 2wt% CaC12 in to the leach liquor.

• Proceedings of the Korean Fiber Society Conference
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• 2002.04a
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• pp.215-218
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• 2002

Poly(vinyl alcohol)(PVA)는 1924년 W. O. Herrmann과 W. Haehnel이 Poly(vinyl esters)를 caustic soda 용액에서 비누화하여 합성한 뒤 많은 연구 및 사용되어지고 있는 고분자이다. 환경친화적이고, 인체에 무해하여 인공관절, 콘택트 렌즈 등에 이용이 되고 있다. 특히 구조가 선형적이고 zig-zag구조를 가지기 때문에 고강도, 고탄성을 갖는 섬유의 제조가 가능한 소재이다[1]. PVA섬유의 제조는 용매를 이용한 습식방사 및 겔방사로 섬유를 제조한다. (중략)

• Korean Journal of Food Science and Technology
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• v.35 no.2
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• pp.201-205
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• 2003

The optimum autolysis conditions were investigated to prepare yeast autolyzate (extract) using yeast slurry collected from brewery plants. Brewers yeast slurry was washed with caustic soda to eliminate bitter hof substances attached to yeast cell walks. The pH of brewers yeast slurry was adjusted to 9.8 with caustic soda, and centrifuged at 3,000 rpm for 5 min. The supernatant was discarded, and the bottom cake was rehydrated and collected. Bitterness unit (BU) of washed yeast slurry was 24.1 BU, below the threshold value of 25.0. Yeast extract could be obtained from washed brewers yeast slurry at maximum yield up to 38% by autolyzing at pH 6.8 and $53^{\circ}C$ for 20 h.

• Resources Recycling
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• v.13 no.4
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• pp.11-16
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• 2004

In this study, treatment conditions for monazite concentrate in Hong-Cheon area deposit were studied with NaOH fritting decomposition and HCl leaching experiments. At condition of NaOH fritting decomposition, it was appropriate to adopt particle size of -200 mesh monazite, reaction temperature of about $460^{\circ}C$ and NaOH/TREO mole ratio of 6. In case of HCl leaching for decomposed product, it was appropriate to use hydrochloric acid of above 8N with leaching temperature of above $80^{\circ}C$, leaching time of 2 hrs and pulp density of about 10%. A rate of decomposition and leaching for monazite was above 90% under optimum conditions. Sodium phosphate compound was effectively recovered from NaOH decomposed solution, and mixed rare earth chloride solution was prepared with HCl leaching of decomposed product.

• Journal of the Korean Wood Science and Technology
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• v.51 no.6
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• pp.509-525
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• 2023

This study has delved into the evolution of Hanji-manufacturing molds and techniques from ancient times to the present, aiming to uncover the current state of traditional Hanji-making techniques. In the absence of records on Hanji-making, various ancient documents, rare books, and documents during the Japanese occupation period, among other artifacts and relics, were analyzed in this study. It was discovered that a sudden significant transformation occurred in the Hanji field during the Japanese occupation period. Soda ash and caustic soda were commonly used for the pretreatment of White bark. Furthermore, a chemical bleaching powder was introduced for the pretreated White bark. Additionally, manual beating of the bark was replaced by mechanical beating methods. While these changes brought convenience to papermakers, they also resulted in a deterioration of Hanji quality. Furthermore, it was revealed that the term "Hanji" has been in use since at least 1908. Furthermore, this study clarified that Heulimtteugi is not the only traditional Hanji-making method in Korea. Instead, there existed Korea's own traditional Gadoomtteugi method, at least up to the 1930s, before the Japanese-style Gadoomtteugi became common in Korea. Additionally, for the first time, this study raises the possibility of the adoption of mold-hanging techniques into Korea's Heulimtteugi method from foreign sources.

• Journal of Fashion Business
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• v.11 no.1
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• pp.125-135
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• 2007

Each cotton fiber is a unicellular hair collected from the seed of cotton plant. The fiber contains many convolutions along its length. Mercer was the first to suggest caustic soda treatment of cotton in commercial application. Mercerization has been commercially used since Lowe's suggestion to endow cotton with increased strength and affinity for dyes with additional properties such as fabric touch or luster. In this study, cotton fabric specimens were mercerized to investigate the changes in physical and mechanical properties pertaining to the hand or touch of fabrics. Physical properties were measured using the KES(Kawabata Evaluation System).

• Computers and Concrete
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• v.17 no.2
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• pp.255-269
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• 2016

The waste glass sludge is a waste produced in the glass industry. It is in a dust form and disposed with water. In the disposal process, various cohesive agents are incorporated in order to precipitate the glass particles efficiently. In this paper, we investigate the pozzolanic reaction of the waste glass sludge incorporating precipitation additives experimentally. The consumption of calcium hydroxide, the setting time and the compressive strength and the pore structure were tested for two different types of the waste glass sludge depending on whether precipitation additives were used. It was found that the waste glass sludge incorporating the precipitation additives had a higher pozzolanic potential than the reference waste glass sludge without precipitation additives.