In situ loading MnO₂ onto 3D Aramid nanofiber aerogel as High-Performance lead adsorbent

Fabricating a high-performance adsorbent as a desirable candidate for removing Pb²⁺ from aqueous water remains a challenge. Aramid nanofibers (ANFs) are promising building blocks that have realized multifunctional applications due to their intrinsic mechanical and chemical stability. Herein, an in situ loading strategy for preparing nanofiber composite aerogel was proposed by assembling ANFs into a 3D aerogel and applying it as host media for the in situ polymerization of pyrrole followed by facile redox reaction between the polypyrrole (PPy) and MnO₄^-1 to load manganese dioxide (MnO₂). The idea was to fully exploit the structural advantages of ultra-low bulk density, large specific surface area, and high porosity of ANFs, and the possible chemical adsorption characteristics of MnO₂ on the basis of ion exchange reaction. The adsorption capacity of 3D ANF/MnO₂ composite aerogel was as large as 554.36 mg/g for Pb²⁺. The adsorption mechanism based on an exchange reaction between Pb²⁺ and protons on the surface of MnO₂ was also investigated. The desorption results showed that the adsorption performance could remain up to 90% after five times of usage. In conclusion, this research provides promising insights into the preparation of high-performance lead adsorbent for water treatment.