Controlled synthesis of nano Fe 3 O 4 @aerogel composites and investigation of their high-efficiency acid-resistant phosphorus adsorption performance

The efficient extraction and utilisation of phosphorus from strongly acidic phosphoric acid industrial waste liquids is of significant economic value and environmental benefit. However, existing adsorbent materials are deficient in simultaneously achieving high adsorption capacity and stability in extremely acidic environments. The present study developed an acid-resistant phosphorus adsorbent based on in-situ loading of Fe3O4 nanoparticles, addressing both precise nanoparticle regulation and composite material structural design. An innovative coprecipitation reaction system was utilised, in which trace water was employed as a reactant (non-solvent) and triethylamine was introduced as a Lewis base ligand. Utilising an in-situ growth methodology, composite Fe3O4 nanoparticles were constructed on a SiO2 aerogel (SiO2 AE@Fe3O4) composite adsorbent. It has been demonstrated that the material exhibits over 80% adsorption efficiency, even in strongly acidic, high-concentration phosphoric industrial wastewater (initial phosphate concentration >500 mg/L). Following ten adsorption-desorption cycles, the adsorption capacity exhibited a decline of merely 10%, while achieving a highly efficient recovery of phosphorus resources (recovery rate >92%), thereby demonstrating its remarkable industrial application potential. The present study proposes a novel material design and technical solutions for the efficient recovery and recycling of phosphorus resources under extreme acidic conditions.