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RISS 인기검색어
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- 저자 : ( Yeongran Hong ) (검색결과 3 건)
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Gold Recovery using Porphyrin-based Polymer from Electronic Waste: Adsorbent Regeneration and Reuse
( Jieun Sona ),( Cafer T. Yavuz ),( Yeongran Hong ),( Thien Nguyen ),( Jong-in Han ) 한국폐기물자원순환학회(구 한국폐기물학회) 2019 ISSE 초록집 Vol.2019 No.-
Due to the rapid development of innovations, the amount of discarded electrical or electronic equipment, called electronic wastes, have been gradually increased over the world and as a consequence, the treatment of the wastes brought a great attention to many researchers. Despite its small amount, precious metals in electronic wastes have large potential values as a future secondary source of metals. However, separation and refining of these metals are complicated and none of them are chosen to be commercialized. As one of the promising adsorbents, porphyrin-based porous polymer, named COP-180, has been developed for the selective adsorption and separation of gold. Although the characteristics and adsorption abilities of COP-180 has been deeply investigated, the strategies on the desorption and recovery of adsorbed gold and the regeneration of the polymer are still unknown. Herein, a hydrometallurgical method for efficient gold desorption and recovery from COP-180 was suggested. Chloride, thiosulfate and thiourea, which are typical non-cyanide gold leaching solutions, were evaluated for gold desorption from the polymer. Leaching solution of thiourea in acidic condition provided the best desorption performance. The results of FTIR analysis showed that the structure of COP-180 was maintained during desorption with thiourea, while changes of structures were detected with acid chloride solution as it supported the suitability of thiourea in either gold desorption or adsorbent regeneration. The ratio of adsorbed gold over the polymer was varied to analyze its effect on desorption efficiency. The less amount of gold was adsorbed on the polymer, the higher gold desorption efficiency was obtained. More than 98% of the adsorbed gold was desorbed from COP-180 by the treatment of 0.1M of thiourea for 2 hours at 50°C. The regeneration and reusability of the adsorbent was evaluated in three consecutive cycles. All these present works suggested that the desorption method via acid thiourea can offer a workable way of efficient gold recovery and regeneration of the adsorbent.
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Kim, Jeonga,Kim, Kyeong Rak,Hong, Yeongran,Choi, Sunyoung,Yavuz, Cafer T.,Kim, Jin Woong,Nam, Yoon Sung American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.24
<P>Metal recovery from electronic waste and industrial wastewater has attracted increasing attention to recycle precious metals and inhibit the emission of hazardous heavy metals. However, the selective recovery of precious metals with a large quantity is still very challenging because wastewater contains a variety of different cations while precious metal ions are relatively scarce. Here, we introduce a simple method to selectively increase the adsorption of gold ions using tannin-coated porous polymer microspheres through photochemical reduction. Mesoporous poly(ethylene glycol dimethacrylate-<I>co</I>-acrylonitrile) microspheres with an average pore diameter of 13.8 nm were synthesized and used as an adsorbent matrix. Tannic acid (TA) was deposited onto the internal pores of the polymer matrix by simple immersion in an aqueous milieu. TA coatings increased the maximum number of adsorbed gold ions by 1.3 times because of the well-known metal ion chelation of TA. Under light illumination, the maximum number of adsorbed gold ions dramatically increased by 6.1 times. We examined two distinct mechanisms presumably involved in the enhanced adsorption: the photooxidation of TA and plasmon-induced hot electrons. Moreover, TA-coated microspheres exhibited remarkable selectivity for gold ions among competing metal ions commonly found in waste resources. This work suggests that the photochemically activated TA can serve as an excellent adsorbent for the selective and efficient recovery of gold ions from wastewater.</P> [FIG OMISSION]</BR>
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