TY - JOUR
T1 - Sorption of H3BO3/B(OH)4- on calcined LDHs including different divalent metals
AU - Qiu, Xinhong
AU - Sasaki, Keiko
AU - Osseo-Asare, Kwadwo
AU - Hirajima, Tsuyoshi
AU - Ideta, Keiko
AU - Miyawaki, Jin
N1 - Funding Information:
Financial support was provided to KS by Funding Program for Progress 100 in Kyushu University. This study was partially supported by the New Energy and Industrial Technology Development Organization (NEDO) under the Innovative Zero-emission Coal-fired Power Generation Project.
Publisher Copyright:
© 2015 Elsevier Inc.
PY - 2015/5/1
Y1 - 2015/5/1
N2 - LDHs with different divalent metals (Zn-LDH, Mg-LDH and Ca-LDH) have been synthesized and produced calcined LDHs (Zn-CLDH, Mg-CLDH and Ca-CLDH) for borate removal. Based on XRD, SEM, BET, 27Al NMR, CO2-TPD, and 11B NMR, detailed characterization of different CLDHs before and after reaction with the boron species was systematically performed. The surface area, basicity and the particle charge of the different CLDHs, which are related to the hydration and regeneration, were markably influenced by the nature of the divalent metals. Transformation of crystal phases and the types of boron species adsorbed by the different CLDHs varied as time changed. The regeneration of Ca-CLDH required the shortest time. However, Ca-LDH decomposed to release Ca2+ ions, forming ettringite with borate. Zn-CLDH also rapidly transformed into Zn-LDH. During this reconstruction, B(OH)4- was intercalated into the interlayer of Zn-LDHs, which is the predominant mechanism of borate removal by Zn-CLDH. Increase in the initial pH caused a competition between borate and OH- so that the removal efficiency of borate by Zn-CLDH decreased. For Mg-CLDH, surface complexation and electrostatic attraction were included in the first stage, immobilizing boric acid into Mg(OH)2 and attracting borate as interlayer anionic species into the new forming Mg-LDHs in the second stage.
AB - LDHs with different divalent metals (Zn-LDH, Mg-LDH and Ca-LDH) have been synthesized and produced calcined LDHs (Zn-CLDH, Mg-CLDH and Ca-CLDH) for borate removal. Based on XRD, SEM, BET, 27Al NMR, CO2-TPD, and 11B NMR, detailed characterization of different CLDHs before and after reaction with the boron species was systematically performed. The surface area, basicity and the particle charge of the different CLDHs, which are related to the hydration and regeneration, were markably influenced by the nature of the divalent metals. Transformation of crystal phases and the types of boron species adsorbed by the different CLDHs varied as time changed. The regeneration of Ca-CLDH required the shortest time. However, Ca-LDH decomposed to release Ca2+ ions, forming ettringite with borate. Zn-CLDH also rapidly transformed into Zn-LDH. During this reconstruction, B(OH)4- was intercalated into the interlayer of Zn-LDHs, which is the predominant mechanism of borate removal by Zn-CLDH. Increase in the initial pH caused a competition between borate and OH- so that the removal efficiency of borate by Zn-CLDH decreased. For Mg-CLDH, surface complexation and electrostatic attraction were included in the first stage, immobilizing boric acid into Mg(OH)2 and attracting borate as interlayer anionic species into the new forming Mg-LDHs in the second stage.
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U2 - 10.1016/j.jcis.2014.12.093
DO - 10.1016/j.jcis.2014.12.093
M3 - Article
AN - SCOPUS:84921465560
SN - 0021-9797
VL - 445
SP - 183
EP - 194
JO - Journal of Colloid and Interface Science
JF - Journal of Colloid and Interface Science
ER -