[en] Graphical abstract: - Highlights: • A uniform MnO₂ layer was anchored onto diatomite surface. • Kinetics and isotherms over MnO₂ modified diatomite were studied. • The Pb(II) adsorption is based on ion-exchange mechanism. - Abstract: A novel method to produce composite sorbent material compromising porous diatomaceous earth (DE) and surface functionalized amorphous MnO₂ is reported. Via a simple in situ redox reaction over the carbonized DE powders, a uniform layer of amorphous MnO₂ was anchored onto the DE surface. The hybrid adsorbent was characterized by X-ray diffraction, scanning electron microscopy, and infrared spectroscopy. The batch method has been employed to investigate the effects of surface coating on adsorption performance of DE. According to the equilibrium studies, the adsorption capacity of DE for adsorbing lead ions after MnO₂ modification increased more than six times. And the adsorption of Pb²⁺ on the MnO₂ surface is based on ion-exchange mechanism. The developed strategy presents a novel opportunity to prepare composite adsorbent materials by integrating nanocrystals with porous matrix