• YAKHAK HOEJI
• /
• v.45 no.1
• /
• pp.23-28
• /
• 2001

Hydrotalcite was prepared by reacting with sodium carbonate, magnesium hydroxide and aluminum chloride solutions in this study. The optimum synthesis conditions based on the yield of the product were established by applying Box-Wilson experimental design. It was found that the optimum synthesis conditions of hydrotalcite were as follows ; reacting temperature : 63~9$0^{\circ}C$, concentration of reactant solution : 18.20~19.82%, molar concentration ratio of two reactants [Mg(OH)$_2$] / (AICl$_3$.6$H_2O$) : 6.0, temperature of washing water : 29.0-34.4$^{\circ}C$, drying temperature : 56-77.6$^{\circ}C$. The physicochemical properties of hydrotalcite as medicine were studied by use of chemical analysis, bulk volume test and acid consuming capacity measurements.

• Resources Recycling
• /
• v.28 no.4
• /
• pp.23-29
• /
• 2019

In order to recover pure alumina from balck dross, precipiatation experiments were done to the NaOH leaching solution of mechanically activated black dross. In this work, hydrogen peroxide was added to the synthic solution as a precipitating agent. Among some variables, the concentration of $H_2O_2$ and the volume ratio of $H_2O_2$ to solution showed a remarkable effect on the precipitation of aluminum hydroxide. At the optimum conditions, most of the aluminate was precipitated. Calcination of the aluminum hydroxide at $1200^{\circ}C$ led to the formation of ${\theta}$ and ${\alpha}$-alumina. The charactistics of the synthesized activated alumina was measured by XRD and EDS. The average particles size of the alumina was $3.73{\mu}m$.

• Journal of the Korean Wood Science and Technology
• /
• v.31 no.1
• /
• pp.46-51
• /
• 2003

The feasibility of using bleaching treatments for removing fungal stain was evaluated on heavily stained raiadta pine sapwood. Sodium chlorite and sodium hypochlorite appeared to destain fungal discoloration by providing proper treatment conditions (chemical concentration, treatment temperature, and treatment time), while hydrogen peroxide did not remove fungal stain under the bleaching regimes evaluated. The addition of sodium silicate and sodium hydroxide in the hydrogen peroxide solution as a buffer could remove fungal discoloration completely; however, the color of wood surface turned faint green after bleaching, thereby reducing the lightness of bleached samples. The results suggest that hydrogen peroxide bleaching could be a feasible method for removing fungal discoloration of stained radiata pine sapwood, although further research is needed to solve the problem of color change after bleaching. Also, further tests under field conditions are recommended.

• Journal of the Society of Naval Architects of Korea
• /
• v.61 no.1
• /
• pp.51-60
• /
• 2024

Hi Air Korea and Hanwha ocean are currently developing an Onboard Carbon dioxide Capture System (OCCS) to absorb CO₂ emitted from ship's engine using a sodium hydroxide(NaOH) solution, and converting the resulting salt into a solid form through a chemical reaction with calcium oxide (CaO). The system process involves the following steps; 1)The reaction of CO₂ gas absorption in water, 2)The reaction between carbonic acid (H₂CO₃) and NaOH solution to produce carbonate or bicarbonate, and 3)The reaction between carbonate or bicarbonate and CaO to form calcium carbonate (CaCO₃). And ultimately, the solid material, CaCO₃, is separated and discharged using a separator. The OCCS has been installed on an ship and the test results have confirmed significant reduction effects of CO₂ in the ship's exhaust gas. A portion of the exhaust gas emitted from the engine was transferred to the OCCS using a blower. The flow rate of the transferred gas ranged from 800 to 1384 m³/hr, and the CO₂ concentration in the exhaust gas was 5.1 vol% for VLSFO, 3.7 vol% for LNG and a 12 wt% NaOH solution was used. The results showed a CO₂ capture efficiency of approximately 42.5 to 64.1 vol% and the CO₂ capture rate approximately 48.4 to 52.2kg/hr. Additionally, to assess the impact of the discharged CaCO₃on the marine ecosystem, we conducted "marine ecotoxicity test" and performed Computational Fluid Dynamics (CFD) analysis to evaluate the dispersion and dilution of the discharged effluent.

• Korean Chemical Engineering Research
• /
• v.43 no.2
• /
• pp.324-329
• /
• 2005

The efficiency of reducing nitric oxide using urea combined with alkali salt additives is reported in this study. The inlet concentration of NO is 500 ppm with air flow rates of 3 and 5 L/min. Reduction of NO was studied from 650 to $1,050^{\circ}C$ with urea concentrations of 0.3 to 1 mol/L. The efficiency for the reduction of NO increased by 44% when urea is added alone. A further increase in efficiency was observed in the presence of NaOH as additive in fact, the efficiency was increased by more than 25% and 75% when 0.5 mol/L and 1 mol/L NaOH were added with the urea. The efficiency for the reduction of NO increased with all additives, but descended in the order NaOH, $Na_2CO_3$, $NaNO_3$, HCOONa, and CHCOONa. The maximum efficiency of NaOH and $Na_2NO_3$ are 74% and 73%, respectively. All these additives did not alter the comparatively wide operating temperature window for reducing NO. However, sodium compounds do not shift the maximum NO concentration towards lower temperatures when the NO removal activity enhances.

• Korean Journal of Veterinary Research
• /
• v.10 no.1
• /
• pp.5-10
• /
• 1970

Due to the fact that an inactivated anthrax vaccine may lark its immunogenicity and stability of immunogen a number of spore vaccines were exclusively used worldwide. In these studies a number of important factors were emphasized to achieve the following: selection of non or less allergic strain of anthrax bacillus, capsulation of bacteria. obtaining of non sporulating but vegetative organisms, adequate inactivation of B. anthraccis by means of formalin, adsorption of immunogen to aluminum hydroxide gel. Non or less allergic strains of anthrax bacillus which is inactivated with formalin was selected by a hyperimmunization and shock test in rabbits. Obtaining capsular material and vegetative immunogen, a virulent anthrax organisms were cultivated on sodium bicarbonate medium with of without adding of l-alanine in which B, anthracis grew luxuriantly without forming spores. Inactivation was carried out at $37^{\circ}C$ water bath for 3 days after the bacterial culture was mixed with formalin, in a final concentration of two per cent of formalin. Aluminum hydroxide gel was added to the mixture of anthrax and blackleg bacterin. Vaccines were injected guinea pig via subcutaneous or intramusoular route and challenged after three weeks and the possibilities of protection was tested. Throughout the studies. the above mentioned vaccines possibly protected the vaccinated guinea pigs more than 80 per cent compared to that of the controls. This experimental results strongly suggest that the vaccine may possibly applicable to bovine.

• Applied Biological Chemistry
• /
• v.33 no.3
• /
• pp.223-230
• /
• 1990

Gelatinization properties of heat-moisture treated Olchal(japonica) and Hankangchalbyeo(j x indica) waxy rice starches were compared. The blue value, light transmittance of starch suspension and viscosity in sodium hydroxide solution were similar between two starches. Olchal starch showed lower water binding capacity, swelling power md peak viscosity by amylograph than Hankangchalbyeo starch. Upon heat-moisture treatments all above parameters were decreased. The critical sodium hydroxide concentration for gelatinization was increased by treatments. The initial pasting temperature of Olchal starch was higher than that of Hankarlgchalbyeo. All amylograph reference points increased by the treatments, except the maximum viscosity or 2l% moisture-treated Olchal starch. Starches treated at 18% moisture level showd the highest value of consistency index. The activation energy of consistency index for gelatinized Olchal starch was lower than that for Hankangchalbyeo starch. The heat-moisture treatments had no effect on activation energy.

• Journal of Korean Society of Environmental Engineers
• /
• v.28 no.6
• /
• pp.661-666
• /
• 2006

The compressive strength of a paste composed of a low-calcium Class F fly ash and alkaline activator solutions was investigated. These activator solutions, made with sodium hydroxide, water glass and water, have a very high $OH^-$ concentration. The composition of alkaline activator solution and temperature have been shown to notably influence the development of the compressive strength of the fly ash-cements paste. Compressive strength of 50 MPa could be achieved by curing of the fly ash at $60^{\circ}C$ for 48 hrs or $85^{\circ}C$ for 24 hrs. This study presented the optimum mixing ratio of Class F fly ash/sodium hydroxide/water glass as 25:8:2 in weight basis, and activator/fly ash as 0.6/1.0 for high strength paste.

• Nuclear Engineering and Technology
• /
• v.56 no.5
• /
• pp.1803-1812
• /
• 2024

The attractive properties of gadolinium-based nanoparticles as a positive contrast agent for magnetic resonance imaging (MRI) have piqued the interest of both researchers and clinicians. Nonetheless, due to the biotoxicity of gadolinium (III) ions' free radicals, there is a need to address this issue. Therefore, this research aimed to develop a biocompatible, dispersible, stable, hydrophilic, and less toxic cellulose nanocrystals/gadolinium oxide nanocomposite as contrast agent properties for MRI purposes. This study aimed to synthesize gadolinium oxide nanoparticles coated with cellulose nanocrystals with polyethylene glycol and sodium hydroxide (CNCs-PEG/NaOH)/Gd₂O₃ using the gamma irradiation method to reduce the particle size. The results showed that using a gamma irradiation dose of 10 kGy, quasi-spherical morphology with a size of approximately 5.5 ± 0.65 nm could be produced. Furthermore, the cytocompatibility of (CNCs-PEG/NaOH)/Gd₂O₃ nanocomposite synthesized was assessed through MTT assay tests on Hep G2 cells, which demonstrated good cytocompatibility without any cytotoxic effects within a concentration range of (10 ㎍/mL - 150 ㎍/mL) and had sufficient cellular uptake. Moreover, the T₁-weighted MRI of (CNCs-PEG/NaOH)/Gd₂O₃ nanocomposite revealed promising results as a positive contrast agent. It is envisaged that the gamma irradiation method is promising in synthesizing (CNCs-PEG/NaOH)/Gd₂O₃ nanocomposite with nanoscale for different applications, especially in the radiotherapy field.

• Fashion & Textile Research Journal
• /
• v.6 no.5
• /
• pp.660-666
• /
• 2004

This article describes the change of hand value of chitosan crosslinked cotton fabrics. The chitosan crosslinked cotton fabrics were manufactured by mercerizing process using epichlorohydrin(ECH) as crosslinkins agent, 2% aqueous acetic acid as a solvent of chitosan and ECH, and 20% aqueous sodium hydroxide as a mercerizing agent and crosslinking catalyst. Cotton fabrics were dipped in the mixed solution of chitosan and ECH, picked up by mangle, mercerized and crosslinked in NaOH solution, and finally wash and dry. Mechanical and physical properties of the chitosan crosslinked fabric were investigated using Kawabata Evaluation System(KES) and other instruments. Tensile energy and tensile strain were decreased with the increase of the concentration of chitosan. Tensile resilience, compression resilience bending rigidity, bending hysteresis, shear stiffness, shear hysteresis, coefficient of friction, geometrical roughness, compression linearity, compressional energy, and thickness were increased with the increase of the concentration of chitosan. On the other hand, bending rigidity, bending hysteresis, coefficient of friction, geometrical roughness, compressional resilience, and thickness were increased with the increase of the concentration of crosslinking agent(epichlorohydrin).