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( Khino J. Parohinog ),( Hiluf Fissaha ),( Erwin C. Escobar ),( John Edward L. Sio ),( Hern Kim ),( Grace M. Nisola ),( Wook-jin Chung ) 한국폐기물자원순환학회 2022 ISSE 초록집 Vol.2022 No.-
The temperature-responsive Pd<sup>2+</sup>-selective crown ether (Dithia-B18CE6) and N-Isopropylacrylamide (NIPAM) polymer brushes were grafted via SI-ATRP on the acid-stable multi-walled carbon nanotube (MWCNT) support material and was utilized as a Pd<sup>2+</sup>-selective adsorbent. The temperature-responsive composite adsorbent was characterized and tested to determine its Pd<sup>2+</sup> adsorption capacity and kinetics. The adsorbent has high selectivity towards Pd<sup>2+</sup> as compared to other cations present in the simulated catalytic converter leachate solution. Recyclability experiment was done by temperature-swing adsorption-desorption cycles for the capture and release of Pd<sup>2+</sup>. The results demonstrate that the Pd<sup>2+</sup>-selective temperature-responsive adsorbent is effective and suitable for the recovery of Pd<sup>2+</sup> from highly acidic sources.
Highly Selective Lithium Recovery from Brine using LNCM/Ag and LNMO/Ag Battery System
( Khino J. Parohinog ),( Chosel P. Lawagon ),( Grace M. Nisola ),( Wook-jin Chung ),( Seong Poong Lee ) 한국폐기물자원순환학회(구 한국폐기물학회) 2019 ISSE 초록집 Vol.2019 No.-
Lithium shortage is inevitable due its massive demand growth for use in electric vehicles (EVs) and various technologies. Therefore, recovery of lithium from other sources such as seawater, brine, and Li-containing wastewater has been gaining attention in energy-related fields. However, the challenge is to find an environmentally benign and energy-efficient processes with fast Li<sup>+</sup> production rate for sustainable Li<sup>+</sup> supply. Electrochemical Li<sup>+</sup> recovery from aqueous solutions is an attractive method as it provides fast recovery rate. However, several studies on this process are challenged with the stability of the materials in aqueous environment and large amount of energy needed entailing high production cost. Until recently, electrochemical related Li<sup>+</sup> extraction has yet to realize its feasibility for industrial-scale application. The success of electrochemical method relies on utilizing highly effective electrodes that can selectively capture Li<sup>+</sup> at a fast rate and at a competitive uptake capacity with minimal energy requirement. Delithiated Li<sub>1-x</sub>Ni<sub>1/3</sub>Co<sub>1/3</sub>Mn<sub>1/3</sub>O<sub>2</sub> (NCM) or Li<sub>1-x</sub>Ni<sub>0.5</sub>Mn<sub>0.5</sub>O<sub>4</sub> (NMO) paired with silver (Ag) were introduced as new electrochemical systems for Li<sup>+</sup> recovery from brine. Material and electrochemical characterizations confirm Li<sup>+</sup> selectivity and stability of NMO/Ag or NCM/Ag in aqueous phase. Using brine as Li<sup>+</sup> feed source, NMO/Ag or NCM/Ag electrochemically captured Li<sup>+</sup> and Cl- at an applied current (C-rate) and operation time (min step-1). Reversal of the current in a receiving solution prompted the release of LiCl. Under optimal conditions, NCM can produce 96.4% pure Li<sup>+</sup> from brine by expending 2.60 W·h mol<sup>-1</sup> Li<sup>+</sup> while NMO can produce 98.1% pure Li+and expending 1.30 - 1.50 W·h mol<sup>-1</sup> Li<sup>+</sup>. In cycled experiments (n = 20), NMO/Ag and NCM/Ag can selectively accumulate Li<sup>+</sup> from brine demonstrating its stability. These promising results indicate that both electrochemical systems can be developed for highthroughput Li<sup>+</sup> mining process with low energy requirement. This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education(2018R1D1A1B07048007).
( Khino J. Parohinog ),( Grace M. Nisola ),( Wook-jin Chung ),( Seong Poong Lee ) 한국폐기물자원순환학회(구 한국폐기물학회) 2019 ISSE 초록집 Vol.2019 No.-
Lithium recovery from seawater has gained significant attention as it can address the anticipated challenges in lithium supply shortages in the future. Due to the complex composition of aqueous Li+ sources, advanced materials need to be developed for selective Li<sup>+</sup> recovery. A multi-functional adsorbent which can effectively capture Li+ and can be regenerated is preferred. Herein, multi-functional composite adsorbents were successfully fabricated and used as a selective Li<sup>+</sup> adsorbent. Graphene oxide (GO) was used as a high aspect ratio support material. Magnetite (Fe<sub>3</sub>O<sub>4</sub>) was immobilized on GO to produce a GO support material with a magnetic property (magnetic graphene oxide of MGO). The MGO was functionalized with different types of diazonium salts to obtain a clickable MGO (Alkyne- MGO) or a hydroxyl-functionalized MGO (OH-MGO). The OH-MGO was reacted with phosphonitrilic chloride trimer (HCTP), glycidol, and sodium azide to synthesize a different type of clickable HCTP-MGO (N<sub>3</sub>-HCTP-MGO). 2-hydroxymethyl-12-crown-4 (OH-12CE4) was used as Li<sup>+</sup>-specific ionophore and was subjected to chemical modification to convert the material into an azide (N<sub>3</sub>- 12CE4) or an alkyne (Alkyne-12CE4). The modified CEs and clickable MGOs were reacted via azide-alkyne Huisgen cycloaddition click chemistry reaction to immobilize the CEs on the support affording different types of composite adsorbents: 12CE4-MGO (N<sub>3</sub>- 12CE4 + Alkyne-MGO) and 12CE4-HCTP-MGO (Alkyne-12CE4 + N<sub>3</sub>-HCTP-MGO). The synthesized composite adsorbents were characterized using Boehm Titration, Transmission Electron Microscopy (TEM), X-ray Diffraction Spectrometry (XRD), Raman Spectroscopy, and X-ray Photoelectron Spectroscopy (XPS). XPS results reveal the presence of the Fe<sub>3</sub>O<sub>4</sub> and the triazole formed during click chemistry reaction of the 12CE4. The adsorbent materials were systematically tested to determine the Li<sup>+</sup> adsorption capacity and adsorption kinetics. The selectivity of the composite adsorbents was tested using seawater as the feed solution. Repeated material adsorption-desorption experiments were done to determine the material stability. Thus, the integration of both magnetite and 12CE4 on the GO support material resulted to the Li<sup>+</sup>-selective, magnet-responsive composite adsorbents which are suitable for long-term Li+ adsorption application. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2018R1D1A1B07048007 and 22A20130012051(BK21Plus).