• Journal of the Korean Chemical Society
• /
• v.42 no.5
• /
• pp.539-548
• /
• 1998

Multidentate N,O-containing ligands, such as N,N'-bis(2-hydroxybenzyl)-ethylenediamine(BHED), N,N'-bis(2-hydroxybenzyl)-propylenediamine(BHPD), N,N'-bis(2-hydroxybenzyl)-diethylenetriamine(BHDT), N,N'-bis(2-hydroxybenzyl)-triethylenetriamine(BHTT) and N,N'-bis(2-hydroxybenzyl)-tetraethylenepentaamine (BHTP) were synthesized by reduction of the imine group of Bis(salicylidene)-ethylendiamine(BSED), Bis (salicylidene)-propylenediamine(BSPD), Bis(salicylidene)-diethylentriamine(BSDT), Bis(salicylidene)-triethylenetetraamine(BSTT) and Bis(salicylidene)-tetraethylenepentaamine(BSTP). Proton dissociation constants of the ligands and stability constants of transition metal(Ⅱ) ion complexes with BHED, BHPD, BHDT, BHTT, and BHTP were determined by potentiometic titration. The sequence of stability constants $(logK_{ML})$ of complex increases as BHED Zn(Ⅱ) which follows the Irving-Williams series.

• Journal of the Korean Vacuum Society
• /
• v.20 no.5
• /
• pp.374-380
• /
• 2011

Carbon coils could be synthesized on nickel catalyst layer-deposited silicon oxide substrate using $C_2H_2$ and $H_2$ as source gases and $SF_6$ as an additive gas under thermal chemical vapor deposition system. The characteristics (formation density and morphology) of as-grown carbon coils according to the injection stage of $SF_6$ gas incorporation were investigated. A continuous injecting of $SF_6$ gas flow could give rise to many types of carbon coils-related geometries, namely linear tub, micro-sized coil, nano-sized coil, and wave-like nano-sized coil. However, the limitation of the geometry as the nano-sized geometries of carbon coils could be achieved by the incorporation of $SF_6$ in a short time (1 min) during the initial deposition stage. A delayed injection of a short time $SF_6$ gas flow can deteriorate the limitation of the geometries. It confirms that the injection time and its starting point of $SF_6$ gas flow would be very important to determine the geometries of carbon coils.

• Resources Recycling
• /
• v.20 no.6
• /
• pp.63-70
• /
• 2011

Enviromental friendly leaching process for the recovery of cobalt and copper from the cobalt concentrate was investigated by organic acids as a leaching reagent. The experimental parameters, such as organic acid type, concentrations of leachant, time and temperature of the reaction as well as the solid to liquid ratio were tested to obtain the optinum conditions for the leaching of cobalt and copper. The results showed that citric acid was the most effective leaching reagent among the organic acids used in this experiment. About 99% of cobalt, 95% of copper and 70% of nickel was dissolved by 2.0 M of citric acid. Addition of 3.0 vol.% of hydrogen perioxide was effective to enhance the leaching efficiency and the optinum temperature was found to be about $70^{\circ}C$.

• Applied Chemistry for Engineering
• /
• v.10 no.2
• /
• pp.218-224
• /
• 1999

Continuous ion exchange characteristics of the synthetic coolant contained Ni, Co and Ag ions of low concentration in acidic-oxidizing conditions have been studied to suggest the guideline for the optimum operation of mixed-bed demincralizer during the shutdown period of a pressurized water reactor (PWR). In the effect of the form of cation resins on the removal capacity of metal ions, the performance of a $H^+$-form resin was about 6% higher than that of a $Li^+$-form resin. Mixed-bed of cation and anion resins in comparison with nonmixed-bed of them, had no affected on the removal capacity of metal ions but very slightly increased the slope of breakthrough curves of metal ions. In the effect related to acidic-oxidizing conditions of the coolant, the addition of boric acid very slightly decreased the slope of breakthrough curves of metal ions, while the addition of hydrogen peroxide slightly decreased the removal capacity of metal ions.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.30 no.6
• /
• pp.1-6
• /
• 2002

Micro engine that includes Micro scale combustor is fabricated. Design target was focused on the observation of combustion driven actuation in MEMS scale. Combustor design parameters are somewhat less than the size recommended by feasibility test. The engine structure is fabricated by isotropic etching of the photosensitive glass wafers. Electrode is formed by electroplating of the Nickel. Photosensitive glass can be etched isotropically with almost vertical angle. Bonding and assembly of structured photosensitive glass wafer from the engine. Combustor size was determined to be 1mn scale. Piston in cylinder moves by fuel injection and reaction. In firing test, adequate engine operation including ignition, flame propagation and piston motion was observed. Present study warrants further application research on MEMS scale internal combustion power units.

• Journal of the Korean Electrochemical Society
• /
• v.10 no.1
• /
• pp.36-42
• /
• 2007

In general, the battery and the(electric) condenser are pictured as electrical energy storage devices. Although there were lots of inventions and utilizations of morden conveniences according to enormous growth of the science and technologies after the Industrial Revolution, a speed of technology development on these devices being closely used in civilized human lives and many electric or electronic systems as a core component are relatively slower to the other fields of technologies. Nevertheless, based on a remarkable progress of the material science and technologies for the last ten years, a new type of electrical energy storage device so called as 'electrochemical capacitors' are being developed and used practically. The electrochemical capacitors exhibit their own characteristics of much enhanced capacitance over the conventional condensers and also distinctively exhibit a longer lift time and higher power capability that the nickel hydrogen batteries and secondary batteries such as lithium ion and polymer batteries does not show up so for. Hence, in this paper, it is intended to introduce a fundamental understanding and updated technology trends on the electrochemical capacitors.

• Korean Journal of Materials Research
• /
• v.7 no.3
• /
• pp.234-243
• /
• 1997

The crystal structure of arc melted $ZrV_{x}Mn_{1-x}Ni_{1.0},\;ZrV_{x}Mn_{0.8-x}Ni_{1.2},\;ZrV_{x}Mn_{0.6-x}Ni_{1.4}$ alloys which are known to have AB2 type Laves structure was investigated. They had mixed phases of C14 and C15. The radius ratio ($r_{A}/r_{B}$) of atoms in A site to that of B site was found to be an important parameter in explaining the omposition dependence of the crystal structure The C15 structure showed a linear increase with the ratio in as-cast conditions. However, the annealed alloys revealed a definite ratio at which the stability of both phases are divided distinctly. The composition of the alloys could be closely controlled by maintaining the argon pressure in the chamber over 1 arm during arc melting. In contrast, the alloy ingot melted in VIM showed a significant loss of hln.

• Resources Recycling
• /
• v.13 no.4
• /
• pp.32-38
• /
• 2004

Recently, Orimulsion (a bitumen-in emulsion) has received increasing attention as an alternative fuel. Orimulsion combusion produces an ash rich in V, Ni and Mg which are processed to recover metals. As a basic study to recover V from Orimulsion ash, physico-chemcial properties and leaching behaviours were investigated. Orimulsion ash was fine size grains ($d_{50}$ 5.9 $\mu\textrm{m}$) with 16% V, 4 % Ni and 9% S. Vanadium was easily leached in water because Orimulsion ash was mainly constituted of metal sulfates. However, the increase of leaching temperature decreased the extraction percentage of vanadium because of hydrolysis of V(V) to vanadium pentoxide. The addition of sulfuric acid could increase the leaching percentage vanadium. In case of alkaline leaching for selective recovery of vanadium, the oxidzing agent such as $H_2$$O_2$ is required to improve the leaching per-centage

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.34 no.3
• /
• pp.92-97
• /
• 2024

To improve the efficiency of water splitting systems for hydrogen production, the high overvoltages of electrochemical reactions caused by catalysts in the oxygen evolution reaction (OER, Oxygen Evolution Reaction) must be reduced. Among them, LDH (Layered Double Hydroxide) compounds containing transition metal such as Ni, are attracting attention as catalyst materials that can replace precious metals such as platinum that are currently used. In this study, nickel foam, an inexpensive metallic porous material, was used as a support, and NiCo LDH (Layered Double Hydroxide) nanocrystals were synthesized through a hydrothermal synthesis process. In addition, changes in the shape, crystal structure, and water decomposition characteristics of the Mo-doped NiCo LDH nanocrystal samples synthesized by doping Mo to improve OER properties were observed.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.28 no.5
• /
• pp.211-216
• /
• 2018

The recovery of rare earth elements (REE) including La, Nd and Ce from spent batteries is important issues to reuse scarce resources. Herein, we present a simple recovery process to obtain lanthanum oxide ($La_2O_3$) from spent Ni-MH batteries, and demonstrate the conversion mechanism from $NaLa(SO_4)_2{\cdot}H_2O$ to $La_2O_3$. This strategy requires the initial preparation of $NaLa(SO_4)_2{\cdot}H_2O$ and subsequent metathesis reaction with $Na_2CO_3$ at $70^{\circ}C$. This metathesis reaction resulted in the crystalline lanthanum carbonate hydrate ($La_2(CO_3)_3{\cdot}xH_2O$) powder with plate-like morphology. On the basis of TGA result, the $La_2(CO_3)_3{\cdot}xH_2O$ powder was calcined in air at three different temperatures, that is, $300^{\circ}C$, $500^{\circ}C$, and $1000^{\circ}C$. As the calcination temperature increased, the morphology of powder was changed; prism-like ($NaLa(SO_4)_2{\cdot}H_2O$) ${\rightarrow}$ platelike ($La_2(CO_3)_3{\cdot}xH_2O$) ${\rightarrow}$ aggregated irregular shape ($La_2O_3$). Futhermore, XRD results indicated that the crystalline $La_2O_3$ could be synthesized after the metathesis reaction with $Na_2CO_3$, followed by heat-treatment at $1000^{\circ}C$, along with a change of crystallographic structures; $NaLa(SO_4)_2{\cdot}H_2O$ ${\rightarrow}$ $La_2(CO_3)_3{\cdot}xH_2O$ ${\rightarrow}$ $La_2O_3$.