Manganese-crosslinked porous carbon for phosphorus recovery and soil remediation: A sustainable strategy featuring fast adsorption and controlled release

Abstract

Developing efficient systems to recover phosphorus (P) from water is critical for mitigating aquatic eutrophication and advancing sustainable P cycling. Herein, a porous carbon skeleton was synthesized via pyrolysis of manganese-crosslinked sodium alginate (Mn/SA-C-S) for efficient P adsorption and subsequent soil remediation. Mn/SA-C-S exhibited rapid P adsorption (14.61 mg/g within 200 min) and controlled release (∼10% desorption over 500 min) via precipitation and surface complexation. The P-rich Mn/SA-C-S (Mn/SA-C-S-P) sustains soil available P (∼109 mg/kg), enhances plant P uptake, and reduces P loss. Crucially, Mn/SA-C-S-P application significantly reshaped the soil microbial community, enriching key functional groups involved in nutrient cycling. Life cycle assessment revealed that Mn/SA-C-S production emits 9.19 kg CO₂ eq, which is 1.9 to 17.62 times lower than values reported in the literature for biochar-based materials. Producing one ton of Mn/SA-C-S-P yields a net benefit of $487.48. This study provides a proof of concept for recovering P from wastewater and reusing it as a resource toward sustainable P management.