• Journal of Magnetics
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• v.20 no.3
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• pp.241-245
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• 2015

A study on the preparation of nickel oxide nanoparticles using electron beam irradiation is described. Nickel nanoparticles were synthesized with nickel chloride hexahydrate as a metal precursor and different sodium hydroxide concentrations using electron beam irradiation. The effects of sodium hydroxide concentration and electron beam absorbed doses were investigated. The samples were synthesized at different sodium hydroxide concentrations and with absorbed doses of 100 to 500 kGy at room temperature. Synthesized nanoparticles were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) and a vibrating sample magnetometer (VSM). The nanoparticle morphologies seemed to be non-spherical and aggregated. The 1:1 molar ratio of nickel chloride hexahydrate and sodium hydroxide showed a higher purity and saturation magnetization value of 13.0 emu/g. The electron beam absorbed dose was increased with increasing nickel nanoparticle nucleation.

• Asian-Australasian Journal of Animal Sciences
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• v.1 no.2
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• pp.65-71
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• 1988

This study reports light and electron microscope examination of rumen fungal colonization of alkali-treated roughage feeds incubated in decron bags in the rumen of cannulated sheep for varying time intervals. Six roughages, pre-treated with ammonium hydroxide or sodium hydroxide at 4% (w/w) level were examined together with untreated control samples. Alkali pre-treatment was associated with an earlier and more pronounced fungal colonization than all control roughages. Sodium hydroxide pre-treatment was significantly more effective than ammonium hydroxide in improving the susceptibility of roughages to rumen fungal colonization and studies by SEM showed that the pre-treatment permitted greater penetration of feeds by fungi. Sodium hydroxide pre-treatment also significantly increased dry matter disappearance from feed held in Dacron bags in the rumen with all feeds except Lucerne stem. It is not known to what extent fungal activity contributed to increased breakdown of the feeds.

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.05a
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• pp.50-50
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• 1994

• Journal of the Korean Wood Science and Technology
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• v.49 no.1
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• pp.14-22
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• 2021

The objective of this study was to investigate the effect of alkali-washing with different sodium hydroxide concentrations on the chemical compositions of steam-treated Betung bamboo strand. Strands were subjected to steam treatment at 126 ℃ for 1 h under 0.14 MPa pressure and followed by washing with 1-5% sodium hydroxide solution for 30 sec. The alteration of structural and non-structural chemical components content of bamboo strands was evaluated. Steam and washing treatments with various concentrations of sodium hydroxide solution considerably reduced the extractive content of bamboo strands, and the cell wall chemical components of the strand in the small degree. FTIR analysis showed noticeable changes in peaks related to hemicellulose and lignin. The relative crystallinity increased significantly after steam and washing treatment with sodium hydroxide up to 3% concentration. SEM Images showed smooth and clean strands surface after washing with 3% sodium hydroxide.

• Resources Recycling
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• v.32 no.3
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• pp.38-44
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• 2023

Leaching tests were conducted using sulfuric acid and sodium hydroxide solutions to remove impurities from domestic graphite concentrate. As a result of the leaching experiment using sulfuric acid solution and sodium hydroxide solution, respectively, the difference of removal efficiency was insignificant when the concentration of sodium hydroxide or sulfuric acid was 2 mol/L or more. The fixed carbon content increased with increasing the temperature in the sulfuric acid solution leaching, while it remains constant above 150℃ in sodium hydroxide solution. For the repeated sequential leaching tests, the leaching conditions were 2 mol/L NaOH, 200℃, 1 hour in the sodium hydroxide solution leaching and 2 mol/L H₂SO₄, 100℃, 1 hour in the sulfuric acid solution leaching, respectively. When sulfuric acid leaching followed by sodium hydroxide solution leaching was repeated 5 times, the fixed carbon increased to 99.95% and ash content decreased to 0.048%, while the fixed carbon increased to 99.98% and ash content was reduced to 0.018 when sodium hydroxide solution leaching followed by sulfuric acid solution leaching was repeated 5 times.

• 한국문화재보존과학회:학술대회논문집
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• 2004.10a
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• pp.66-71
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• 2004

When waterlogged wood dries up, it shrinks largely. And it is hard to recover original shape. Therefore it happens to lose the value of wood remains frequently. This paper studied how far dried waterlogged wood can recover original shape. Shape recovering course and extent are thoroughly investigated after waterlogged wood of Pinus densiflora, Quercus serrata and Styrax japonica oven-dries and instills varieties of test solution. At 1- step, oven-dried samples infiltrated by chlorous acid sodium or sodium hydroxide solution. At 2- step, wood tissues of samples were swelled by the fast decompression after infiltrating $CO_2-supercritical$ fluid at high pressure. The study investigated the possibility of shape recovering in waterlogged wood. Shape recovering rate is different with solution and wood species. Sample of sodium hydroxide solution doesn't swell anymore when using $CO_2-supercritical$ fluid. In general, the sample of sodium hydroxide solution has higher Shape recovering rate than $CO_2-supercritical$ fluid solution treated by chlorous acid sodium.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.6
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• pp.26-33
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• 2012

This paper reported on the effect of blended activator on the physical properties of alkali-activated slag mortar. Five different activators(caustic alkalis) were used: sodium hydroxide(NaOH, A Case), calsium hydroxide($Ca(OH)_2$, B Case), magnesium hydroxide($Mg(OH)_2$, C Case), aluminum hydroxide($Al(OH)_3$, D Case), and potassium hydroxide(KOH, E Case). We blended five caustic alkalis with sodium carbonate($Na_2CO_3$). The dosage of five caustic alkalis was 3M and sodium carbonate was 1M, 2M and 3M. The result of flow and setting time was decrease as the dosage of sodium carbonate increase. But the compressive strength was increase as the dosage of sodium carbonate increase. It was shown that there is a good effect of blended caustic alkalis with sodium carbonate in alkali-activated slag mortar.

• Journal of the Korean Chemical Society
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• v.16 no.4
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• pp.249-256
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• 1972

Hadong-Kaolin was treated with aqueous sodium hydroxide solution. The crystalline structure was studied by X-ray powder diffraction method. The optimum conditions for various crystal formation were as follows: Crystal Concentration Temp. reating time Halloysite 1~4 N NaOH $60^{\circ}C$ 0.5${\sim}$4 hr Sodium A zeolite 0.5${\sim}$2 N NaOH 80${\sim}$$100^{\circ}C$ 6${\sim}$20 hr Hydoxysodalite > 4 N NaOH 80${\sim}$$100^{\circ}C$ > 4 hr The ratio of $Na_2O to SiO_2$ for crystallizing sodium A zeolite was 0.5-1.5. The $Ca^{++}$ ion exchange capacity of produced sodium A zeolite for 0.2 N $CaCl_2$ solution at $25^{\circ}C$ was amounted to 65% of theoretical value.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.199-200
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• 2019

The purpose of the research is assessing the possibility of strength recovery for mortar added with accidently high amount of fly ash. For compressive strength at 28 day, the sample painted with sodium hydroxide showed higher compressive strength than the sample painted with calcium hydroxide. Regarding the curing conditions, the curing temperature 65℃ provided better conditions than the curing temperature 20℃ in aspect of solution penetration depth and reactivity of fly ash. In the case of drying after saturation, the case painted with sodium hydroxid 65℃ showed the clearest engrossing mark.

• Journal of the Korea Concrete Institute
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• v.24 no.6
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• pp.745-752
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• 2012

This paper studies the effect of the compressive strength for combined alkali-activated slag mortars. The effect of activators such as alkali type and dosage factor on the strength was investigated. The alkalis combinations made using five caustic alkalis (sodium hydroxide (NaOH, A series), calcium hydroxide ($Ca(OH)_2$, B series), magnesium hydroxide ($Mg(OH)_2$, C series), aluminum hydroxide ($Al(OH)_3$, D series), and potassium hydroxide (KOH, E series)) with sodium carbonate ($Na_2CO_3$) were evaluated. The mixtures were combined in different dosage at 1M, 2M, and 3M. The study results showed that the compressive strength of combined alkali-activated slag mortars tended to increase with increasing sodium carbonate. The strength of combined alkali-activated slag mortars was better than that of control cases (without sodium carbonate). The result from scanning electron microscopy (SEM) analysis confirmed that there were reaction products of calcium silicate hydrate (C-S-H) and alumina-silicate gels from combined alkali-activated slag specimens.