Hydrogen-bond dominated phosphorus uptake by chitosan-calcium alginate coated melamine foam in ecological floating beds

Abstract

Traditional ecological floating beds (EFBs) employing quartz sand, gravel, or ceramsite as substrate materials face limitations in efficiently accumulating and rendering phosphorus accessible to plants within these systems. Herein, we introduce a novel substrate, chitosan-calcium alginate coated melamine foam (CC/SC@MF), designed to augment phosphorus removal in EFBs. This substrate capitalizes on hydrogen bonding to selectively adsorb phosphate from actual landscape water, thereby facilitating the assimilation of accumulated phosphate by plants. Our fabricated CC/SC@MF exhibits an impressive phosphate adsorption capacity of 179.72 mg P/g, surpassing the performance of recently reported hydrogel-based adsorbents. Furthermore, its efficacy in removing phosphate from actual landscape water, even at low phosphorus concentrations as minimal as 0.3 mg/L, has been duly confirmed. Experiments integrated with density functional theory calculations uncover that the formation of hydrogen bonds is responsible for phosphorus accumulation by CC/SC@MF, and the synergy of –OH, –NH2, and –COOH groups within chitosan and alginate molecules contributes to the enhanced phosphorus uptake. Strikingly, EFBs utilizing the CC/SC@MF substrate exhibit a notably enhanced phosphorus uptake efficiency at a reduced cost in comparison to conventional commercial alternatives. This underscores the robust techno-economic feasibility of CC/SC@MF for managing phosphorus in real-world landscape water systems.