One-Step Fabrication of Recyclable Konjac Glucomannan-Based Magnetic Nanoparticles for Highly Efficient Cr(VI) Adsorption

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-Fe3O4 NPs) with excellent adsorption properties and recyclability for heavy metals were prepared using an one-step precipitation method. The as-prepared KGM-Fe3O4 NPs have a spherical morphology of superparamagnetism with a small particle size (ca. 7.0 nm) and a large specific surface area (160.1 m2·g−1). 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-Fe3O4 NPs, and the maximum adsorption capacity of Cr(VI) onto KGM-Fe3O4 NPs was calculated to be 41.67 mg·g−1 using the Langmuir isotherm model. In addition, KGM-Fe3O4 NPs with adsorbed heavy metal ions can be quickly recovered from a solution, regenerated, and reused in the next cycle. KGM-based Fe3O4 nanoparticles are promising adsorbents that show significant reusability for the removal of metal ions in water and wastewater treatment.