Floatable magnetic aerogel based on alkaline residue used for the convenient removal of heavy metals from wastewater

[Display omitted] •First report magnetic aerogel spheres based on alkaline residue/alginate composite to remove heavy metal ions.•Mechanical strength of the composite aerogel spheres increased 10 times.•Possess excellent floating persistence, feasible separability and good recycling stability.•Faici...

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Published in:Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 399; p. 125760
Main Authors: Wang, Shao-Jie, Bu, Huaitian, Chen, Huo-Jun, Hu, Tian, Chen, Wen-Zhao, Wu, Jin-Hua, Hu, Han-Jian, Lin, Min-Zhao, Li, Yongtao, Jiang, Gang-Biao
Format: Journal Article
Language:English
Published: Elsevier B.V 01-11-2020
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Summary:[Display omitted] •First report magnetic aerogel spheres based on alkaline residue/alginate composite to remove heavy metal ions.•Mechanical strength of the composite aerogel spheres increased 10 times.•Possess excellent floating persistence, feasible separability and good recycling stability.•Faicile fabrication, easy industrialized production, efficient adsorption to Cd(II), satisfying recyclability. The present work introduces a novel strategy for preparation of a recyclable aerogel absorbent for heavy metal purification of industrial wastewater. The absorbent (Fe3O4/SA-AR) is based on a combination Fe3O4, alginate (SA) and industrial alkaline residue (AR) waste, forming a cost-efficient and easily recyclable spherical aerogel. The magnetic aerogel spheres of the Fe3O4/SA-AR are light-weight with a loose porous structure and a mechanical strength 10 times that of conventional SA aerogels, thus sustaining up to 20 cycles of compression-relaxation. This excellent structure stability guarantees long-term integrity and floatability of the aerogel spheres in water. Adsorption experiments on the heavy metal Cd(II) suggested that equilibrium was approached within 2 h. The maximum adsorption capacity was 38.83 mg/g, higher than reported for conventional SA aerogel absorbents. After 5 cycles of adsorption–desorption, the aerogel spheres still maintained an adsorption efficiency of 90%, and had good stability and reusability. Studies on kinetic and adsorption isotherm models showed that the adsorption of Cd(II) to Fe3O4/SA-AR correlated well with the pseudo-second-order kinetic model and the Langmuir isotherm model. FTIR, SEM-EDS and XPS analyses indicated that the adsorption of Cd(II) to the Fe3O4/SA-AR aerogel was mainly driven by formation of OH complexation, electrostatic adsorption and ion exchange. In summary, this work suggests a new route for synergetic resource utilization of value-less and pollutive alkaline residual for the removal of heavy metals in wastewater.
ISSN:1385-8947
1873-3212
DOI:10.1016/j.cej.2020.125760