| Summary: | Recently, the natural polymer polysaccharide konjac glucomannan (KGM) has received attention as a promising adsorbent in water treatment due to its low toxicity, cost-effectiveness and biocompatibility. However, the high-level water absorbency of KGM makes it difficult to recover in water treatment. In this study, by combining KGM with magnetic nanoparticles, KGM-based magnetic nanoparticles (KGM-Fe<sub>3</sub>O<sub>4</sub> NPs) with excellent adsorption properties and recyclability for heavy metals were prepared using an one-step precipitation method. The as-prepared KGM-Fe<sub>3</sub>O<sub>4</sub> NPs have a spherical morphology of superparamagnetism with a small particle size (ca. 7.0 nm) and a large specific surface area (160.1 m<sup>2</sup>·g<sup>−1</sup>). Taking Cr(VI) as the target heavy metal ion, the above nanoparticles have a high adsorption capacity and fast adsorption rate for Cr(VI). The pseudo-second order kinetic model is more suitable to describe the adsorption process of Cr(VI) by KGM-Fe<sub>3</sub>O<sub>4</sub> NPs, and the maximum adsorption capacity of Cr(VI) onto KGM-Fe<sub>3</sub>O<sub>4</sub> NPs was calculated to be 41.67 mg·g<sup>−1</sup> using the Langmuir isotherm model. In addition, KGM-Fe<sub>3</sub>O<sub>4</sub> NPs with adsorbed heavy metal ions can be quickly recovered from a solution, regenerated, and reused in the next cycle. KGM-based Fe<sub>3</sub>O<sub>4</sub> nanoparticles are promising adsorbents that show significant reusability for the removal of metal ions in water and wastewater treatment.
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