TY - JOUR
T1 - Influence of silicate on the structural memory effect of layered double hydroxides for the immobilization of selenium
AU - Tian, Quanzhi
AU - Guo, Binglin
AU - Sasaki, Keiko
N1 - Funding Information:
This research was supported to KS by the Japan Society for the Promotion of Science (JSPS) KAKENHI (No. JP19H00883 ) and to TQ by the China Scholarship Council (No. 201706420068 ).
Publisher Copyright:
© 2020 Elsevier B.V.
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2020/8/5
Y1 - 2020/8/5
N2 - The influence of silicate on the structural memory effect of layered double hydroxides (LDHs) has been rarely reported. In this study, five kinds of calcined LDHs (CLDHs) were synthesized and used as adsorbents for the sorption of selenium with or without silicate, under the initial pH 10 and 13, respectively, characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), infrared spectroscopy (IR), nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), and N2 adsorption-desorption isotherm. The results indicated that silicate can significantly affect the phase transformation of CLDHs, and the sorption amounts of selenite and selenate dramatically decreased in the presence of silicate. Specifically, silicate can react with MgO and Al2O3 in CLDHs to generate magnesium silicate hydrate and geopolymer-like substance which were covered on the surface of particles, blocking the hydroxylation of metal oxides. However, higher pH suppressed the interaction between MgO and silicate and enhanced the formation of geopolymer-like substance, which promoted the regeneration of LDHs. Al in CLDHs plays a critical role in the regeneration of LDHs. Besides, the ternary oxides (CLDH-2, Mg2Al0.75Fe0.25-oxide; CLDH-3, Mg2Al0.5Fe0.5-oxide) possessed larger specific surface areas (127.7 and 158.2 m2/g) and consequently presented more resistance to the effect of silicate.
AB - The influence of silicate on the structural memory effect of layered double hydroxides (LDHs) has been rarely reported. In this study, five kinds of calcined LDHs (CLDHs) were synthesized and used as adsorbents for the sorption of selenium with or without silicate, under the initial pH 10 and 13, respectively, characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), infrared spectroscopy (IR), nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), and N2 adsorption-desorption isotherm. The results indicated that silicate can significantly affect the phase transformation of CLDHs, and the sorption amounts of selenite and selenate dramatically decreased in the presence of silicate. Specifically, silicate can react with MgO and Al2O3 in CLDHs to generate magnesium silicate hydrate and geopolymer-like substance which were covered on the surface of particles, blocking the hydroxylation of metal oxides. However, higher pH suppressed the interaction between MgO and silicate and enhanced the formation of geopolymer-like substance, which promoted the regeneration of LDHs. Al in CLDHs plays a critical role in the regeneration of LDHs. Besides, the ternary oxides (CLDH-2, Mg2Al0.75Fe0.25-oxide; CLDH-3, Mg2Al0.5Fe0.5-oxide) possessed larger specific surface areas (127.7 and 158.2 m2/g) and consequently presented more resistance to the effect of silicate.
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U2 - 10.1016/j.jhazmat.2020.122674
DO - 10.1016/j.jhazmat.2020.122674
M3 - Article
C2 - 32335282
AN - SCOPUS:85083446221
SN - 0304-3894
VL - 395
JO - Journal of Hazardous Materials
JF - Journal of Hazardous Materials
M1 - 122674
ER -