• Applied Chemistry for Engineering
• /
• v.8 no.6
• /
• pp.920-926
• /
• 1997

The catalytic glycolysis process is the method of chemical recycling where the polyol and carbamate compounds recovered by transesterification reaction are reused to produce new polyurethane foams. In this work, ethylene glycol, diethylene glycol, and 1,4-butanediol were used to decompose polyurethane foams and various metallic acetates were provided as catalysts. The catalytic glycolsis of polyurethane foams was taken place in the reaction temperature of $180{\sim}200^{\circ}C$. The reaction rates of catalytic glycolysis reaction were indicated by the viscosity of the reaction products at different reaction times. IR and GPC analysis showed the types and the molecular weight distributions of the products. The catalytic glycolysis was profitable for using ethyleneglycol at high temperature. The activities of the catalysts are suitable for K, Na, Tl acetate, and the products are composed of comparatively high-contained amine compounds and carbamate compounds. In the case of Sr acetate and Quinoline, the reaction rate was somewhat low. However, the content of polyol was high and the content of the side-products was low. The foams which were prepared by blending up to 20wt% of recovered polyol with virgin polyols showed better physical properties in tensile strength, hardness, tear strength, and compressive strength compared to those of polyurethane foams from virgin polyol.

• Resources Recycling
• /
• v.28 no.4
• /
• pp.30-36
• /
• 2019

In this study, Li powder was recovered from the by-product of LNO ($Li_2NiO_2$) process, which is the positive electrode active material of waste lithium ion battery, through the $CO_2$ thermal reaction process. In the process of recovering Li powder, the $CO_2$ injection amount is 300 cc/min. The $Li_2NiO_2$ award was phase-separated into the $Li_2CO_3$ phase and the NiO phase by holding at $600^{\circ}C$ for 1 min. After this, the collected sample:distilled water = 1:50 weight ratio, and after leaching, the solution was subjected to vacuum filtration to recover $Li_2CO_3$ from the solution, and the NiO powder was recovered. In order to increase the purity of Ni, it was maintained in $H_2$ atmosphere for 3 hours to reduce NiO to Ni. Through the above-mentioned steps, the purity of Li was 2290 ppm and the recovery was 92.74% from the solution, and Ni was finally produced 90.1% purity, 92.6% recovery.

• Microbiology and Biotechnology Letters
• /
• v.50 no.3
• /
• pp.414-421
• /
• 2022

In this study, we isolated Weizmannia ginsengihumi LGHNH (KCTC 14462BP) from 30-year-old wild Panax ginseng C.A. Meyer and elucidated the characteristics of the isolated bacterium and its industrial potential as an anti-aging material. W. ginsengihumi LGHNH was investigated to produce indole-3-acetic acid (IAA), a plant growth-promoting hormone (1.38 ㎍/ml to 2.22 ㎍/ml). We also confirmed the existence of bioconversion activity via the comparison of the ginsenoside content before and after fermentation. As for the converted minor ginsenoside, Rg2(R), Rg4, Rg6, Rg3(S), Rg3(R), Rk1, Rg5, Rh1(R), Rk3 and Rh4 are known to have high bioavailability and various skin effects. We measured mitochondrial membrane potential and ATP biosynthesis to elucidate W. ginsengihumi LGHNH cultured product (WCP) as an anti-aging material. As a result, the mitochondrial membrane potential in HaCaT cells with UVB decreased to 39.3% compared to the unirradiated group, but was recovered to 57.3% and 58.1% by 0.001% (v/v) and 0.01% (v/v) WCP, respectively. In addition, we measured mitochondrial ATP biosynthesis. It decreased to 94.3% compared to the unirradiated group with UVB, but was recovered to 105.3% and 105.7% by 0.001% (v/v) and 0.01% (v/v) WCP.

• Journal of Powder Materials
• /
• v.21 no.4
• /
• pp.286-293
• /
• 2014

The electrochemical properties of cells assembled with the $LiNiO_2$ (LNO) recycled from cathode materials of waste lithium secondary batteries ($Li[Ni,Co,Mn]O_2$), were evaluated in this study. The leaching, neutralization and solvent extraction process were applied to produce high-purity $NiSO_4$ solution from waste lithium secondary batteries. High-purity NiO powder was then fabricated by the heat-treatment and mixing of the $NiSO_4$ solution and $H_2C_2O_4$. Finally, $LiNiO_2$ as a cathode material for lithium ion secondary batteries was synthesized by heat treatment and mixing of the NiO and $Li_2CO_3$ powders. We assembled the cells using the $LiNiO_2$ powders and evaluated the electrochemical properties. Subsequently, we evaluated the recycling possibility of the cathode materials for waste lithium secondary battery using the processes applied in this work.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.28 no.5
• /
• pp.300-305
• /
• 2015

$WO_3$, $SiO_2$, and $TiO_2$ films with hydrophilic property are deposited by rf-magnetron sputtering. Their wettability is strongly depends on the presence or absence of the oxygen plasma etching on the glass substrates. The $TiO_2$ film of 50 nm-thick on the plasma etched glass shows a water contact angle (WCA) below $5^{\circ}$ which means a super-hydrophilic surface. However, WCA values are gradually degraded when the films are exposed under atmosphere, especially $WO_3$. In order to improve hydrophilic property, the degraded films can be again recovered by UV illumination for 10 sec using UV-light and the $TiO_2$ film shows a super-hydrophilic surface about $3^{\circ}$.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.35 no.4
• /
• pp.260-264
• /
• 2013

Calcium hydroxide root canal filing paste (vitapex) is widely used as canal filling paste for infected canal. However, chemical burn is possible because of the high alkali base of calcium hydroxide. A 57-year old woman was admitted to our clinic for consistent dull pain and paresthesia in the left upper lip, zygoma and buccal cheek area, which developed during an endodontic treatment of the left lateral incisor. Radiographic finding showed radiopaque material, which exits from the left incisor root apex, and was within the left canine and first premolar buccal soft tissue. The overfilled Vitapex extended to the soft tissue was surgically curetted. The result of the surgical curettage was favorable. Though slight hypoesthesia on the upper lip was still remained, paresthesia on zygomatic and buccal cheek area was completely recovered. As far as we know, this is the first case report of infraorbital nerve damage from overfilled Vitapex material.

• Resources Recycling
• /
• v.15 no.1 s.69
• /
• pp.20-27
• /
• 2006

PVC is the thermoplastic offering excellent material properties. PVC has been used in wide variety of applications, however, it causes environmental problems when it is discarded because of its high chlorine content. Since dechlorination reaction of PVC is taking place at relatively low temperature compared to the pyrolysis temperature of plastics, study on the dechlorination reaction has been carried out as a pre-treatment process. Twin screw reactor which shows excellent mixing capabilities is employed. Experimental variables are the first and second reactor temperature, PVC content in mixed plastics, viscosity of mixed plastics, feeding rate, rotational speed or the second reactor. Over $90\%$ of dechlorination ratio can be obtained under proper operation conditions. Chlorine gas evolved from reactor is absorbed in water and can be recovered as a hydrochloric acid. Analysis had been done on chlorine flows by taking material balance over realtor.

• Analytical Science and Technology
• /
• v.26 no.1
• /
• pp.11-18
• /
• 2013

Perchlorate ($ClO{_4}^-$) is the material that is used as propellants of rockets and material of explosive as a form of ammonium perchlorate salts. Ammonium perchlorate solution of high concentration is recovered from expired rocket through demilitarization process by the water-jet method. If people take perchlorate in food and water, it interferes with adsorption of iodide which is the substance needed to synthesize thyroid hormone in the thyroid gland. It has an bad influence upon disturbing pregnancy and synthesis of growth hormone. So the effective method is necessary to remove perchlorate anion in water. By considering economic aspect, we studied effective desorption (regeneration) of perchlorate anion from adsorbent with studies on removal and adsorption of perchlorate anion. Desorption experiment was conducted as batch type. Depending on various conditions (concentration, pH, cation anion form) elution, we evaluated amount, efficiency of desorption(amount of adsorption/desorption ${\times}$ 100). Also, research confirmed the efficiency of mixed resins between anion exchange resin and activated carbon and expected synergic effect from advantages of both adsorbents.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.05b
• /
• pp.8-11
• /
• 2001

In this study. the recovery of plasma induced damage in the etched PZT thin film with $O_2$ re-annealing have been investigated. The PZT thin films were etched as a function of $Cl_2/Ar$ and additive $CF_4$ into $Cl_{2}(80%)/Ar(20)%$. The etch rates of PZT thin films were $1600\dot{A}/min$ at $Cl_{2}(80%)/Ar(20)%$ gas mixing ratio and $1970\dot{A}/min$ at 30 % additive $CF_4$ into $Cl_{2}(80%)/Ar(20)%$. The etched profile of PZT films was obtained above 70 by SEM. In order to recovery properties of PZT thin films after etching, the etched PZT thin films were re-annealed at various temperatures in $O_2$ atmosphere. From the hysteresis curves, ferroelectrical properties are improved by $O_2$ re-annealing process. The improvement of ferroelectric behavior at annealed sample is consistent with the increase of the (100) and (200) PZT phase revealed by x-ray diffraction (XRD). From XPS analysis, intensity of Pb-O, Zr-O and Ti-O peak are increased and the chemical residue peak is reduced by $O_2$ re-annealing. The ferroelectric behavior consistent with the dielectric nature of TixOy is recovered by $O_2$ recombination during rapid thermal annealing process. From AFM images, it shows that the surface roughness of re-annealed sample after etching is improved.

• Proceedings of the Korean Institute of Resources Recycling Conference
• /
• 2005.10a
• /
• pp.83-96
• /
• 2005

PVC is the thermoplastic offering excellent material properties. PVC is used in wide variety of applications, however, it causes environmental problems when it is discarded because of its high chlorine content. Since dechlorination reaction of PVC is taking place relatively low temperature compared to the pyrolysis temperature of plastics, study on the dechlorination reaction has been carried out as a pre-treatment process. Twin screw reactor which shows excellent mixing capabilities is employed. Experimental variables are first and second reactor temperature, PVC content in mixed plastics, viscosity of mixed plastics, feeding rate, rotational speed of the second reactor. Over 90% of dechlorination rate can be obtained under proper operation conditions. Chlorine gas evolved from reactor is absorbed in water and can be recovered as a hydrochloric acid. Analysis had been done on chlorine flows by taking material balance over reactor.