In-situ phosphorus remediation efficiency and mechanism of magnesium-functionalized cellulose-based capturing materials

Eutrophication induced by phosphorus pollution in rural water bodies poses a serious threat to ecological health. Conventional phosphorus adsorbents are constrained by limitations such as inconvenient raw material acquisition or high preparation costs. This study successfully developed a low-cost, high-efficiency magnesium-functionalized cellulose-based phosphorus capture material (Mg-B). Mg-B exhibits a maximum phosphorus adsorption capacity of 105.52 mg/g, significantly surpassing that of non-carbonized biomass adsorbents (2.27–22.73 mg/g) and ranking at a moderate level within the range of magnesium-modified biochar and composite adsorbent (33.6–425 mg/g). Mg-B demonstrates optimal applicability within the pH range of 7–10, achieving phosphorus removal rates of 77–90 % in real rural water bodies (with phosphorus concentrations of 0.80–6.37 mg/L) during continuous-flow experiments and on-site demonstrations. Furthermore, the presence of coexisting anions has minimal impact on the adsorption performance of Mg-B. After phosphorus saturation, Mg-B can be composted into phosphorus-magnesium-enriched organic fertilizer. Complexation and chemical precipitation are the primary mechanisms of phosphorus adsorption by Mg-B, with the formation of RB--MgHPO 4 and RB--Mg 3 (PO 4 ) 2 (RB--Mg 2 + + HPO 4 2- /PO 4 3- → RB--MgHPO 4 /RB--Mg 3 (PO 4 ) 2 ). This study provides a novel approach for utilizing waste biomass cellulose to develop highly efficient phosphorus adsorbents suitable for rural water environments. • Development of low-cost phosphorus adsorbents with local bamboo biomass. • The phosphorus removal rate reached 77–90 % in the field demonstration. • Principal phosphorus adsorption mechanism are complexation and chemical precipitation. • Phosphorus-saturated adsorbent is subsequently converted into organic fertilizer.