• The Journal of Engineering Geology
• /
• v.29 no.2
• /
• pp.163-183
• /
• 2019

We investigated acid mine drainage (AMD) of Bongyang abandoned coal mine, Danyang, Chungbuk Province with emphasis on geochemical contaminants in AMD and precipitates using chemical analyses, XRD, SEM, IR, and $^{27}Al$ NMR. Water chemistry changes with pH and oversaturation of chemical species. According to calculation of saturation index, the AMD is saturated with various Fe, Al minerals. Orange or orcher precipitates are composed of schwertmannite and goethite, associated with Leptothrix orchracea bacteria, whereas whitish precipitates are composed mostly of alumimous minerals such as basaluminite with poor crystallinity. The whitish precipitates include trace $Al_{13}$-Tridecamer. It is important to control the precipitation and solubility of aluminous species for ensuring remediation and control for the AMD discharged from the Bongyang abandoned coal mine.

• The Journal of Engineering Geology
• /
• v.29 no.4
• /
• pp.579-598
• /
• 2019

We investigated geochemical contaminants and Fe, Al behavior in precipitates of acid mine drainage (AMD) from the Donghae abandoned coal mine, Taebaek, Gangwon Province using aqueous chemical analyses, XRD, IR, and ²⁷Al NMR, Our results showed that water chemistry changed with pH and Eh, and saturation indices of chemical species in the AMD. According to saturation calculated by visual MINTEQ, the AMD was saturated with various Fe-, Al-oxyhydroxide minerals. Reddish brown precipitates are composed of schwertmannite, ferrihydrite, and goethite, whereas whitish precipitates are composed mostly of alumimous minerals such as poorly crystallized basaluminite with trace Al₁₃-Tridecamer. It is important to apply active treatment methods rather than simple storage pond and to control the precipitation and solubility of iron species and aluminous species for ensuring remediation and control for the AMD discharged from the Donghae abandoned coal mine.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.35D no.11
• /
• pp.55-61
• /
• 1998

Organic light emitting devices from a single layer thin film with a hole transport polymer, poly(N-vinylcarbazole) (PVK) doped with 2-(4-bi phenyl)-5-(4-t-butyl-phenyl) -1,3,4-oxadiazole (Bu-PBD) as electron transporting molecules and Coumurine 6(C6), 1,1,4,4-tetraphenyl-1,3-butadiene (TPB), Rhodamine B as a emitter dye were fabricated. The sing1e layer structure and the use of soluble materials simplify the fabrication of devices by spin coating technique. The active layer consists of one polymer layer that is simply sandwiched between two electrodes, indium-tin oxide (ITO), and aluminum. In this structure, electron and hole inject from the electrodes to the PVK : Bu-PBD active layer. Respectively, Blue, green and orange colored emission spectrum by the use of TPB, C6, Rhodamine B dye emitted at 481nm, 500nm and 585nm were achieved during applied voltages. PVK materials can be useful as the host polymer to be molecularly doped with other organic dyes of the different luminescence colors. And EL color can be tuned to the full visible wavelength.

• Applied Chemistry for Engineering
• /
• v.29 no.4
• /
• pp.461-467
• /
• 2018

In this study, $(n-BuCp)_2ZrCl_2$, was supported on $SiO_2/MgCl_2$ binary support. Before supporting the catalyst, the $SiO_2/MgCl_2$ binary support was surface treated with three different alkyl aluminum compound, namely trimethylaluminum, triethylaluminum, and ethylaluminum sesquichloride. The synthesized surface-treated $SiO_2/MgCl_2$ supported metallocene catalysts were used for the copolymerization of ethylene and 1-hexene. Their catalytic properties and performances were analyzed through BET, XPS analysis, ICP-AES analysis, and FE-SEM. While the resulting copolymers were analyzed through DSC analysis, GPC analysis, 13C-NMR analysis, and FE-SEM. The analysis of synthesized surface-treated $SiO_2/MgCl_2$ supported metallocene catalysts showed that the Zr content of these catalysts is relatively lower compared to that of the catalyst supported on $SiO_2$. This could be attributed to the reduction in the surface area of $SiO_2$ due to the presence of recrystallized $MgCl_2$ and alkyl aluminum. Furthermore, they exhibited a better copolymerization activity compared to that of $SiO_2$ supported catalyst, particularly the EASC-surface treated binary support, which has the highest activity of 1.9 kg PE/($mmol-Zr^*hr$) because EASC acts as a strong Lewis acid. It could also be observed that the larger the ligand of alkyl aluminum used, the rougher the particle surface of the resulting polymer.

• Journal of the Korean Electrochemical Society
• /
• v.19 no.4
• /
• pp.141-147
• /
• 2016

In this study, homo and copolymers of 2,2,6,6-tetramethyl-4-piperidyl methacrylate(TMA) and synthesized styrene derivative, 2,2,6,6-tetramethylpiperidine-4-vinylbenzyl ether(TVBE) were obtained by radical polymerization and oxidized to produce corresponding polymer radicals. The polymer radicals were mixed with carbon black, binders and coated onto Al current collector. The battery performance is then characterized by fabricating coin cells. As results, the polystyrene based organic radicals show lower oxidize efficiency and discharge capacity than methacrylate based one. However, the former shows better capacities from discharge experiments performed at $60^{\circ}C$ which suggests a possible way to overcome the high temperature fade out of performance in usual organic radical batteries. Also as expected, an excellent C-rate performance is observed in all the cells consisted of organic polymer radicals.

• Journal of the Mineralogical Society of Korea
• /
• v.15 no.4
• /
• pp.273-282
• /
• 2002

Al-pillared montmorillonite was synthesized from Na-saturated montmorillonite which was prepared by ionic substitution from Ca-montmorillonite of the Jabut mine, Gyeongiu City d(001), surface areas, and dehydration and ionic substitution properties have been compared for both Ca-montmorillonite and Al-pillared montmorillonite. d(001) spacings of Ca-montmorillonite and Al-pillared montmorillonite were 15.1 $\AA$ and $18.3\AA$, respectively. Dehydration took place before $350 ^{\circ}C$ in Ca-montmorillonite, whereas linealy up to $550^{\circ}C$ in Al-pillared montmorillonite. BET surface areas are 5～6 times larger in Al-pillared montmorillonite ($192 \m^2$/g) than Camontmorillonite. Ca-montmorilonite shows high selectivity for $Na^{＋}$ /, whereas Al-pillared montmorillonite for $Ca^{2＋}$ . The former shows decreasing d(001) spacing with increasing substitution of $Na^{＋}$ and irregular interstratified structure at high substitution of $Ca^{2＋}$ /, whereas the latter shows linear decreasing pattern in d(001) spacing with increasing $Ca^{ 2+}$.

• Journal of Korean Society of Water and Wastewater
• /
• v.38 no.4
• /
• pp.233-242
• /
• 2024

This study evaluates the potential of various coagulants to enhance the efficiency of total phosphorus removal facilities in a sewage treatment plant. After analyzing the existing water quality conditions of the sewage treatment plant, the coagulant of poly aluminium chloride was experimentally applied to measure its effectiveness. In this process, the use of poly aluminium chloride and polymers in various ratios was explored to identify the optimal combination of coagulants. The experimental results showed that the a coagulants combination demonstrated higher treatment efficiency compared to exclusive use of large amounts of poly aluminium chloride methods. Particularly, the appropriate combination of poly aluminium chloride and polymers played a significant role. The optimal coagulant combination derived from the experiments was applied in a micro flotation method of real sewage treatment plant to evaluate its effectiveness. This study presents a new methodology that can contribute to enhancing the efficiency of sewage treatment processes and reducing environmental pollution. This research is expected to make an important contribution to improving to phosphorus remove efficiency of similar wastewater treatment plant and reducing the ecological impact from using coagulants in the future.