Abstract
Developing bio-based adsorbents for efficient removal of heavy metal ions from water has attracted increasing attention due to their abundance, low cost, and sustainability. However, most of these adsorbents are in powdered or granular forms, suffering from difficult regeneration and poor recyclability. Here, we report a highly porous three-dimensional amino-functionalized wood aerogel for efficient heavy metal adsorption. The amino-functionalized wood aerogel was prepared from natural balsa wood via a delignification treatment, followed by TEMPO-mediated oxidation of the delignified wood and then grafting polyethylenimine (PEI) onto the oxidized cellulose skeleton. The obtained amino-functionalized wood aerogel possessed a unique porous lamellar structure with a low bulk density of 77.2 mg/cm3 and high porosity of 94.9%. Benefiting from its high porosity and the introduced amino groups on the cellulose skeleton, the amino-functionalized wood aerogel exhibited a maximum Cu(II) adsorption capacity of 59.8 mg·g−1, which was significantly higher than those of the TEMPO-oxidized wood aerogel and natural balsa wood. The adsorption process can be well described by the pseudo-second-order and Langmuir isotherm models, indicating that the Cu(II) adsorption by the PEI@wood aerogel was dominated by a monolayer chemisorption process. The developed amino-functionalized wood aerogel provides new insights for the design of efficient and low-cost monolithic absorbents for heavy metal remediation.
Highlights
Heavy metal ions (e.g., Cu(II), Pb(II), and Cd(II)) discharged from industrial wastewater have become one of the major sources of water pollution worldwide, causing harmful impacts on the water environment and human health due to their high toxicity and nondegradability [1]
Natural balsa wood was used as starting materials to prepare the aerogel due to its low density (~220 mg·cm−3) and high porosity (~85.6%)
The fitting results suggested that the adsorption process of the PEI@wood aerogel for Cu(II) could be better described by the pseudo-second-order kinetic model, indicating that the adsorption process was dominated by chemical adsorption
Summary
Heavy metal ions (e.g., Cu(II), Pb(II), and Cd(II)) discharged from industrial wastewater have become one of the major sources of water pollution worldwide, causing harmful impacts on the water environment and human health due to their high toxicity and nondegradability [1]. Various approaches, including ion exchange, membrane filtration, chemical precipitation, flocculation, bioremediation, and adsorption, have been adopted to remove heavy metal ions from wastewater [2] Among these methods, adsorption is considered as one of the most promising approaches due to its advantages of low cost, high efficiency, and simple operation [3, 4]. Bio-based adsorbents, including sawdust, bark, straw, and cellulose, have attracted increasing interest as cheap and sustainable alternatives in wastewater treatment due to their abundance, low cost, and ecofriendliness [6, 7]. Most of these adsorbents are in powdered or granular forms, often causing separation and reuse difficulties in actual wastewater treatment. Developing monolithic adsorbents based on low-cost biomass resources for efficient heavy metal ion removal is highly desirable given their easy separation and recovery in the practical application
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