• Title/Summary/Keyword: Chemical Recycling

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Chemical Recycling Technology from Polyester Wastes (폴리에스터 폐자원의 화학적 재활용기술)

  • Han, Myung-Wan;Kang, Kyung-Suk;Song, Jae-Kyung
    • Elastomers and Composites
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    • v.47 no.2
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    • pp.96-103
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    • 2012
  • This paper reviews recent technologies for recycling poly (ethylene terephthalate) wastes. Wide application and non-biodegradability of the PET creates huge amounts of waste and disposal, leading to an environmental problem and economic loss. Chemical recycling can be a promising technology to deal with these problems by converting the waste into useful feedstock material for polyester production. Chemical recycling of polyethylene terephthalate are processes where the PET polymer chain is destructed by the impact of glycol (MEG) causing glycolysis, methanol causing methanolysis or water causing hydrolysis. After intensive purification polyester oligomers or the monomers MEG, dimethyl telephthalate (DMT) or purified terephthalic acid (PTA) are received which are re-used to produce polyester products.

Depolymerization of Waste Polyurethane from Automotive Seats (자동차 시트용 폐폴리우레탄의 해중합)

  • Min, Sung-Jin;Kong, Seung-Dae;Yoon, Cheol-Hun;Kang, An-Soo;Eom, Jae-Yeol;Shin, Pan-Woo;Lee, Seok-Woo
    • Journal of the Korean Applied Science and Technology
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    • v.18 no.2
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    • pp.103-110
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    • 2001
  • Resource recovery and recycling of materials and products, including polyurethanes is viewed as a necessity in today's society. Most urethane polymers are made from a polyol and a diisocyanate. these and be chemicals such as water, diamines or diols that react with isocyanate groups and add to the polymer backbone. The problems of recycling polyurethane wastes has major technological, economic and ecological significance because polyurethane itself is relatively expensive and its disposal whether by burning is also costly. In general, the recycling methods for polyurethane could be classified as mechanical, chemical and feedstock. In the chemical recycling method, there are hydrolysis, glycolysis, pyrolysis and aminolysis. This study, the work was carried out glycolysis using sonication ant catalyzed reaction. Different kinds of recycled polyols were produced by current method(glycolysis), catalyzed reaction and sonication as decomposers and the chemical properties were analyzed. The reaction results in the formation of polyester urethane diols, the OH value which is determined by the quantity of diol used for the glycolysis conditions. The glycolysis rates by sonication for the various glycols, increased as fallows: PPG

Current Status of Recycling of LED Waste (LED 폐자원의 재활용 현황)

  • Lee, Duk-Hee;Shin, Dongyoon;Kim, Tae-Hyung;Lee, Chan-Gi;Park, Kyung-Soo;Lee, Ki Woong;Lee, Jaeryeong
    • Resources Recycling
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    • v.28 no.2
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    • pp.14-22
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    • 2019
  • Development of technology makes LED an economical option because of lower energy consumption and better environmental impact. Because higher consumer demand the LED market is expanding rapidly due to its environment-friendly advantages. Expansion of LED application, development of various fusion technologies, the emergence of new markets, and the large-scale expansion of markets would lead to a large volume of e-waste generation with valorization potential. Currently, most of the generated waste being that landfilled and incinerated due to the absence of technology and management system. In this paper, we review the current status of LED waste recycling and analyzes the available recycling technologies.

Present Condition on the Recycling and Management for Waste Acids (폐산의 재활용 현황 및 관리 방안)

  • Sim, Yeon Ju;Kim, Eui Yong
    • Korean Chemical Engineering Research
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    • v.48 no.3
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    • pp.300-303
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    • 2010
  • Environmental issues on the waste emission and its treatment are of great interest in these days. In order to resolve the pollution problems, recycling the waste materials is generally recommended. Especially, emission of waste acids in designated sources is increasing every year. In this study, we focused on the effective recycling of the waste acids rather than treatments. Management systems of the waste acids are not systematically designed, and the quality of the waste regulation on the recycling product is unclear in domestic and foreign countries. We surveyed the present conditions on domestic waste emission and recycling of waste acids. For the final analysis of the recycling products, iron chloride, iron sulfate, copper cyanide, copper oxides, and cement copper are selected as candidates. We expect that this article would help establishing the systematic management system on treating the waste acid materials.

Analysis of brightness decrease originated from mixing of flexo printed ONP and OCC in ONP recycling process (플렉소 인쇄 신문지와 OCC 배합에 따른 ONP 탈묵펄프의 백색도 변화)

  • Ryu, Jeong-Yong;Song, Bong-Keun
    • Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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    • 2011.10a
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    • pp.119-123
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    • 2011
  • The application of flexo printed ONP and OCC leads to brightness decrease of deinked stock in ONP recycling system. The largest problems are due to accumulation of flexo ink & introduction of brown fibers. All these are emphasized by variations in the amount of flexo printed ONP and OCC in recovered ONP stock. Most of the brightness problems caused by flexo ink can be helped and solved by applying a proper polyelectrolytes as coagulation agent and flocculation agent. This requires exact evaluation of sedimentation or dissolved air flotation potentials of flexo ink and polyelectrolytes. Effect of bleaching chemical (H2O2) addition level on the increase of brightness of OCC included stock has been investigated by lab scale test.

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Investigation of Low-Cost, Simple Recycling Process of Waste Thermoelectric Modules Using Chemical Reduction

  • Kim, Woo-Byoung
    • Bulletin of the Korean Chemical Society
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    • v.34 no.7
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    • pp.2167-2170
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    • 2013
  • A low-cost and simple recycling process of waste thermoelectric modules has been investigated using chemical reduction methods. The recycling is separated by two processes, such as dissolving and reduction. When the waste thermoelectric chips are immersed into a high concentration of $HNO_3$ aqueous solution at $100^{\circ}C$, oxide powders, e.g., $TeO_2$ and $Sb_2O_3$, are precipitated in the $Bi^{3+}$ and $HTeO{_2}^+$ ions contained solution. By employing a reduction process with the ions contained solutions, $Bi_2Te_3$ nanoparticles are successfully synthesized. Due to high reduction potential of $HTeO{_2}^+$ to Te, Te elements are initially formed and subsequently $Bi_2Te_3$ nanoparticles are formed. The average particle size of $Bi_2Te_3$ was calculated to be 25 nm with homogeneous size distribution. On the other hand, when the precipitated powders reduced by hydrazine, $Sb_2O_3$ and Te nanoparticles are synthesized because of higher reduction potentials of $TeO_2$ to Te. After the washing step, the $Sb_2O_3$ are clearly removed, results in Te nanoparticles.

Development of Depolymerization Method on the Recycling of Waste Flexible Polyurethane Foam (연질 폐우레탄 폼의 재활용을 위한 해중합법 개발)

  • 엄재열;이병학;신판우;김용렬
    • Journal of Environmental Health Sciences
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    • v.28 no.2
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    • pp.41-49
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    • 2002
  • Resource recovery and recycling of materials and products including polyurethanes are viewed as a necessity in today's society. The problems of recycling polyurethane wastes has major technological, economic and ecological significance because polyurethane itself is relatively expensive and its disposal by burning is also costly. In general, the recycling methods for polyurethane could be classified as mechanical, chemical and physical. In the chemical recycling method, there ate hydrolysis, glycolysis, pyrolysis and aminolysis. This study was carried out glycolysis using new method such as sonication and catalyzed reaction. There are kinds of recycled polyols were produced by current method(glycolysis) but, this study were with catalyzed reaction and sonication as decomposers and the chemical properties were analyzed. The reaction results in the formation of polyester urethane diols and then the OH value which is determined by the quantity of diol used for the glycolysis conditions. The glycolysis rates by sonication and catalyzed reaction for the various glycols, increased as: PPG