• Title/Summary/Keyword: Chemical Recycling

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Basic Study for the Recycling of Phosphogypsum (인산부생석고(燐酸副生石膏)의 재활용(再活用)을 위한 기초연구(基礎硏究))

  • Park, Woon-Kyoung;Song, Young-Jun;Lee, Jung-Mi;Lee, Gye-Seung;Kim, Youn-Che;Shin, Kang-Ho;Yoon, Sin-Ae;Park, Charn-Hoon
    • Resources Recycling
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    • v.15 no.2 s.70
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    • pp.58-68
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    • 2006
  • This study is carried out for the purpose of investigating the property of phosphogypsum, and suggesting the proper recycling system for it. The chemical composition, mineralogical composition, particle size distribution and shape of phosphogypsum were investigated. The size distribution and constitution of impurities, distribution of heavy metals are also investigated. In conclusion, the grade and yield of recoverable phosphogypsum were discussed.

Study on Recycling of Scraps from Process of Silicon-single-crystal for Semiconductor

  • Lee, Sang-Hoon;Lee, Kwan-Hee;Hiroshi Okamoto
    • Proceedings of the IEEK Conference
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    • 2001.10a
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    • pp.705-710
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    • 2001
  • So for the quartz-glassy crucible wastes which was used for pulling up silicon-single-crystal ingot have simply reused for refractory raw-materials, or exhausted. This study is concerned on the advanced recycling-technology that is obtained by the proper micro-particle preparation process in order to fabricate fine amorphous silica filler for EMC (Epoxy Molding Compound). Therefore, this paper will deal with the physical, chemical and thermal pre-treatment process for efficient impurity removal and with the proper micro-particle process for producing the amorphous silicafiller. In view of the results, if the chemical, physical and thermal pre-treatment process for efficient elimination of impurity was passed, the purity of wasted fused glassy crucible is almost equal to the its of first anhydrous quartz glass. Thus, it was understood that this wasted fused glassy crucible was sufficient value of recycling, though it was damaged. When the ingot was fabricated, Phase transformation of crystallization by heat treatment (heat hysteresis phenomenon) was not changed. So, it was understood that as fused silica in the amorphous state, as It is, recycling possibility was very high

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Physical Properties of Polymer Composite Recycling Recycled Aggregate (순환골재를 재활용한 폴리머 복합재료의 물성)

  • Hwang, Eui-Hwan;Jeon, Jong-Ki
    • Applied Chemistry for Engineering
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    • v.20 no.1
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    • pp.67-74
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    • 2009
  • Nowadays, recycling of recycled aggregates from the waste concrete is seriously demanded for the protection of environment and the shortage of aggregates owing to the large scale construction project. In this study, for the development of polymer composite recycling recycled aggregates from the waste concrete, twenty five specimens of the polymer composite were prepared with the five levels of replacement ratios of recycled aggregates (0, 25, 50, 75, 100%) and polymer-cement ratios (0,5, 10, 15, 20%), respectively. For the evaluation of the performance of polymer composite specimens, various physical properties such as compressive and flexural strengths, water absorption, hot water resistance, total pore volume and porosity were investigated. As a result, physical properties of polymer composite were remarkably improved with an increase of polymer cement ratios, but greatly decreased with the replacement ratios of recycled aggregates.

Recycling Technology of Crosslinked-Polymers Using Supercritical Fluid (초임계 유체를 이용한 가교고분자 재활용기술)

  • Koo, Chong-Min;Yu, Si-Won;Baek, Bum-Ki;Cho, Hang-Kyu;Lee, Youn-Woo;Hong, Soon-Man
    • Elastomers and Composites
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    • v.47 no.2
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    • pp.111-120
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    • 2012
  • Industrial wastes of crosslinked polymers have been burned or disposed of in landfills because there is no recycling technology due to their insoluble and infusible network chain structure. However, recycling of cross-linked polymers has been taken a growing attention because of issues of environmental pollution and of resources conservation. In this paper, uprising recycling technologies of crosslinked polymers using supercritical fluid are reviewed.

Ligand Effect in Recycled CNT-Pd Heterogeneous Catalyst for Decarboxylative Coupling Reactions

  • Kim, Ji Dang;Pyo, Ayoung;Park, Kyungho;Kim, Gwui Cheol;Lee, Sunwoo;Choi, Hyun Chul
    • Bulletin of the Korean Chemical Society
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    • v.34 no.7
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    • pp.2099-2104
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    • 2013
  • We present here an efficient and simple method for preparation of highly active Pd heterogeneous catalyst (CNT-Pd), specifically by reaction of dichlorobis(triphenylphosphine)palladium ($Pd(PPh_3)_2Cl_2$) with thiolated carbon nanotubes (CNTs). The as-prepared CNT-Pd catalysts demonstrated an excellent catalytic activity for the carbon-carbon (C-C) cross-coupling reactions (i.e. Suzuki, Stille, and decarboxylative coupling reactions) under mild conditions. The CNT-Pd catalyst could easily be removed from the reaction mixture; additionally, in the decarboxylative coupling of iodobenzene and phenylpropiolic acid, it showed a six-times recyclability, with no loss of activity. Moreover, once its activity had decreased by repeated recycling, it could easily be reactivated by the addition of phosphine ligands. The remarkable recyclability of the decarboxylative coupling reaction is attributable to the high degree of dispersion of Pd catalysts in CNTs. Aggregation of the Pd catalysts is inhibited by their strong adhesion to the thiolated CNTs during the chemical reactions, thereby permitting their recycling.

An Application of High-Power Ultrasound to Rubber Recycling

  • Hong, Chang-Kook;Isayev, A.I.
    • Elastomers and Composites
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    • v.38 no.2
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    • pp.103-121
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    • 2003
  • The application of powerful ultrasound to rubber recycling is a very recent field of study. An ultrasonic field creates high frequency extension-contraction stresses by acoustic cavitation. The breakdown of rubber network occurs primarily around pulsating cavities due to the highest level of strain produced by high-power ultrasound. Stronger reductions of cross-link density were observed at a higher pressure, indicating an important role of pressure during ultrasonic recycling. Visible bubbles were observed during ultrasonic treatment as a proof of acoustic cavitation. Shearing effect has a significant influence on improving the efficiency of ultrasonic treatment. After the ultrasonic treatment, the cross-link densities of NR/SBR blends were lower than those of NR and SBR due to the reduced degree of unsaturation and chemical reactions. Carbon black fillers increase the probability of bond scission during ultrasonic treatment, due to the restricted mobility. The mechanical properties of ground tire rubber (GRT)/HDPE blends were improved by ultrasonic treatment and dynamic revulcanization. Ultrasonic treatment of GRT in the presence of HDPE matrix was found to give better mechanical properties due to the chemical reactions between rubber and plastic phases.

Technical Trends in the Patents and Papers for the Recycling of Organic Residues from Waste Printed Circuit Boards (특허(特許)와 논문(論文)으로 본 폐(廢)PCB 유기계(有機界) 잔유물(殘留物) 재활용(再活用) 기술(技術) 동향(動向))

  • Lee, Dai-Soo;Shin, Sera;Cho, Young-Ju;Cho, Bong-Gyoo
    • Resources Recycling
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    • v.22 no.2
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    • pp.71-77
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    • 2013
  • Electronic products such as appliances, computers, and cellular phones have printed circuit boards (PCBs) in common and the PCBs in the waste electronic products contain valuable metals and organic resins. In Korea, recovery and recycling of the organic resins as well as the valuable metallics from the wastes are required indeed as the most of resources are being imported from abroad. In this article, the patents and papers for the recycling of organic residues from the waste PCBs were collected and analyzed. The open patents of USA (US), European Union (EP), Japan (JP), and Korea (KR) and SCI journals from 1979 to 2012 were investigated. The patents and journals were collected using key-words and filtered by the definition of the technology. The patents and journals were analyzed by the years, countries, companies, and technologies and the technical trends were discussed in this paper. It is showed sluggish relatively activity of published papers and patent applications for polymer manufacturing technology in local and abroad.

Recycling Technique of Nano TiO2-Coated Silica-bead (나노광촉매가 코팅된 실리카 비드의 재생 연구)

  • Do, Young-Woong;Ha, Jin-Wook
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.10 no.11
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    • pp.3269-3273
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    • 2009
  • In this study, recycling methods of nano $TiO_2$-coated silica-bead were conducted in order to solve a deactivation problem of bead that had been invented for decomposition of pollutants in aqueous solution. Surface cleansing was selected as the recycling method for used beads. The surface cleansing was done with four different solutions such as distilled water, surfactant, acetone, and ethyl alcohol(ethanol). The recycling process consists of cleansing and calcination. After cleaning the used (deactivated) beads, calcination was done at $100^{\circ}C$, $200^{\circ}C$ and $300^{\circ}C$ for 30 minutes, respectively. This process was repeated three times. The activity of the recycled bead was measured by photo-degradation of methylene blue. The result shows that acetone cleansing and calcination at $100^{\circ}C$ for 30 minutes was the most efficient recycling method.

Physical and Chemical Properties of Waste LCD Glass as Raw Materials for the Production of Foamglass (발포유리 제조원료로서 폐 LCD유리의 물리화학적 특성)

  • Lee, Chul-Tae;Lee, Jinsoo;Jang, Moonho;Lee, Sunyoung
    • Applied Chemistry for Engineering
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    • v.20 no.3
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    • pp.266-272
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    • 2009
  • Physical and chemical properties of waste LCD glass were investigated to test the feasibility of feed materials for the production of foamed glass. For this study, chemical analysis, thermal analysis, rheological consideration with the viscosity change under high temperature and thermal expansion coefficient were carried out and the trial production of foamed glass as; in spherical and block type also attempted. All results showed waste LCD glass would be a good feed material for the production of foamed glass and foaming technology of LCD glass would be an effective recycling alternative.