Synthesis and characterization of multi-walled carbon nanotubes-supported dibenzo-14-crown-4 ether with proton ionizable carboxyl sidearm as Li super(+) adsorbents

A new preparation method for solid-supported crown ethers (CE) as lithium ion (Li super(+)) adsorbents is presented. Hydroxy-dibenzo-14-crown-4 ether (HDB14C4) was immobilized on multi-walled carbon nanotubes (MWCNTs) through the following steps: (1) MWCNTs were oxidized to generate carboxyl groups...

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Bibliographic Details
Published in:Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2015-03, Vol.264, p.89-98
Main Authors: Torrejos, Rey Eliseo C, Nisola, Grace M, Park, Myoung Jun, Shon, Ho Kyong, Seo, Jeong Gil, Koo, Sangho, Chung, Wook-Jin
Format: Article
Language:English
Subjects:
Adsorbents
Adsorption
Carbon
Ethers
Nanostructure
Ring opening
Synthesis
Uptakes
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Summary:A new preparation method for solid-supported crown ethers (CE) as lithium ion (Li super(+)) adsorbents is presented. Hydroxy-dibenzo-14-crown-4 ether (HDB14C4) was immobilized on multi-walled carbon nanotubes (MWCNTs) through the following steps: (1) MWCNTs were oxidized to generate carboxyl groups (COOH) as functionalization sites for (2) epoxide-terminated linkers. The (3) subsequent epoxide ring opening resulted in the attachment of HDB14C4 and generation of a hydroxyl group in which (4) proton ionizable COOH sidearm was etherified as an optional post CE functionalization step. From this synthesis route, two types of adsorbents were produced: type 1 as MWCNTs with neutral HDB14C4 (steps 1-3) and type 2 as MWCNTs with HDB14C4-COOH sidearm (steps 1-4). Functional group titration and gravimetry revealed that the performed reaction steps efficiently modified the MWCNTs which were strongly supported by FTIR and TGA results. Raman and TEM analyses revealed the preservation of structural integrity of the MWCNTs after functionalization. Between the two materials, the presence of a COOH sidearm in CE of type 2 adsorbent significantly enhanced the Li super(+) uptake at pH >=7. A Langmuir-type of Li super(+) adsorption occurred in type 2 adsorbent. Competitive ion adsorption results revealed that type 2 preferred Li super(+) uptake than other metal ions as shown in the sequence: Li super(+) > Na super(+) > Mg super(2+) > Ca super(2+), K super(+), Sr super(2+). Overall results suggest that the developed synthesis route can effectively produce solid-supported CEs which can be used for precious metal ions recovery.
ISSN:1385-8947
DOI:10.1016/j.cej.2014.11.036