TY - JOUR
T1 - Synthesis and selenate removal of magnesium–aluminum-layered double hydroxide particle using magnesium oxide
AU - Tsuchiya, K.
AU - Fuchida, Shigeshi
AU - Tokoro, C.
N1 - Funding Information:
We appreciate the cooperation of Organo Corporation in this study. Part of this work was performed at the Waseda Research Institute for Science and Engineering and Research Organization for Open Innovation Strategy, Waseda University. The morphology analysis was performed by Materials Characterization Central Laboratory and Kagami Memorial Research Institute for Materials Science and Technology, Waseda University. The pore-size distribution analysis was supported by the National Institute for Materials Science. We thank Edanz Group ( https://jp.edanz.com/ac ) for editing a draft of this manuscript.
Publisher Copyright:
© 2022, The Author(s) under exclusive licence to Iranian Society of Environmentalists (IRSEN) and Science and Research Branch, Islamic Azad University.
PY - 2022
Y1 - 2022
N2 - High levels of selenium (Se) sometimes exist in wastewater from coal-fired power plants and mining operations; however, reduction of the Se level to the effluent standard (10 µg dm−3, Japan) is difficult to achieve. Magnesium (Mg)–aluminum (Al)-layered double hydroxides (Mg–Al LDHs) are good adsorbents for hexavalent selenium (Se(VI)), but they tend to have low sedimentation rates. Here, we evaluated the Se(VI)-removal performance (1–50 mg dm−3) and sedimentation rate of a LDH produced from magnesium oxide (MgO) and aluminum (Al) (MgO–Al LDH). To investigate the best conditions for LDH synthesis, three MgO–Al LDHs were compared: MOAL-1 produced by simultaneously mixing MgO and Al in the solution; MOAL-2 produced by adding MgO to the solution and then mixing Al with the suspension after 20–120 min; and MOAL-3 produced by adding MgO to the solution, adding Al to the suspension after 60 min, and then reacting for a further 1–48 h. Morphological analysis showed that the MgO–Al LDH particles were larger (10–250 µm) than general Mg–Al LDH secondary particle aggregates (1–10 µm), which resulted in 8.6–11 times higher sedimentation rate. In addition, the sedimentation rate of MOAL-2 was higher than that of MOAL-1. This could result from the lower amount of fine Mg–Al LDH secondary particle aggregates in MOAL-2 (13%) than in MOAL-1 (28%), which could prevent sedimentation. For MOAL-3, the sedimentation rate gradually increased with increasing reaction time after Al addition, and most of the particles were sedimented within 30 min after reaction for 48 h. X-ray diffraction and pore-size distribution analysis indicated that this could be because of increased crystallization and aggregation during the extended reaction. In conclusion, extending the MgO hydration time and/or MgO–Al reaction time during Mg–Al LDH synthesis is expected to produce Mg–Al LDHs with good Se(VI)-removal performance. Graphical Abstract: [Figure not available: see fulltext.]
AB - High levels of selenium (Se) sometimes exist in wastewater from coal-fired power plants and mining operations; however, reduction of the Se level to the effluent standard (10 µg dm−3, Japan) is difficult to achieve. Magnesium (Mg)–aluminum (Al)-layered double hydroxides (Mg–Al LDHs) are good adsorbents for hexavalent selenium (Se(VI)), but they tend to have low sedimentation rates. Here, we evaluated the Se(VI)-removal performance (1–50 mg dm−3) and sedimentation rate of a LDH produced from magnesium oxide (MgO) and aluminum (Al) (MgO–Al LDH). To investigate the best conditions for LDH synthesis, three MgO–Al LDHs were compared: MOAL-1 produced by simultaneously mixing MgO and Al in the solution; MOAL-2 produced by adding MgO to the solution and then mixing Al with the suspension after 20–120 min; and MOAL-3 produced by adding MgO to the solution, adding Al to the suspension after 60 min, and then reacting for a further 1–48 h. Morphological analysis showed that the MgO–Al LDH particles were larger (10–250 µm) than general Mg–Al LDH secondary particle aggregates (1–10 µm), which resulted in 8.6–11 times higher sedimentation rate. In addition, the sedimentation rate of MOAL-2 was higher than that of MOAL-1. This could result from the lower amount of fine Mg–Al LDH secondary particle aggregates in MOAL-2 (13%) than in MOAL-1 (28%), which could prevent sedimentation. For MOAL-3, the sedimentation rate gradually increased with increasing reaction time after Al addition, and most of the particles were sedimented within 30 min after reaction for 48 h. X-ray diffraction and pore-size distribution analysis indicated that this could be because of increased crystallization and aggregation during the extended reaction. In conclusion, extending the MgO hydration time and/or MgO–Al reaction time during Mg–Al LDH synthesis is expected to produce Mg–Al LDHs with good Se(VI)-removal performance. Graphical Abstract: [Figure not available: see fulltext.]
KW - Layered double hydroxide
KW - Magnesium–aluminum-layered double hydroxide
KW - Sedimentation
KW - Selenate
KW - Wastewater treatment
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U2 - 10.1007/s13762-022-04653-3
DO - 10.1007/s13762-022-04653-3
M3 - Article
AN - SCOPUS:85142654400
SN - 1735-1472
JO - International Journal of Environmental Science and Technology
JF - International Journal of Environmental Science and Technology
ER -