Fungal-derived 3D macroporous adsorbents for rapid Pb(II) removal: Performance, mechanisms and applications

Lead (Pb) bioaccumulation in aquatic ecosystems poses significant threats to environmental health and human safety. To address the urgent need for efficient and operationally simple adsorbents for aqueous Pb(II) removal, this study presents the development of novel biomass adsorbents, specifically xanthate-modified Auricularia auricula (XAAS), Pleurotus ostreatus (XPOS) and Flammulina velutipes (XFVS), for the rapid and selective removal of Pb(II) ions from aqueous solutions. These materials were synthesized via a straightforward xanthate modification followed by lyophilization, optimizing conditions to balance cost-effectiveness and adsorption performance. Structural characterization revealed a three-dimensional macroporous architecture in all adsorbents, enabling rapid solid-liquid separation through simple filtration. Kinetic studies revealed that Pb(II) removal by XAAS, XPOS and XFVS was predominantly chemisorption-driven, reaching equilibrium within 15 min. Langmuir isotherm modeling determined maximum adsorption capacities of 190.48, 161.03 and 170.94 mg/g, respectively, showing minimal temperature dependence. Competitive adsorption experiments established Pb(II) selectivity following the inhibition sequence: Cr(III) > Cu(II) > Cd(II) > Tl(I). Mechanistic studies identified ion exchange, surface complexation and microprecipitation as primary removal pathways. Notably, xanthate hydrolysis within the adsorbent matrices facilitated the formation of PbS and Pb₃(CO₃)₂(OH)₂ nanoparticles. In simulated Pb(II)-contaminated Pearl River water, the adsorbents achieved >86% removal at 34.11 mg/L Pb(II) and complete elimination (100%) at trace levels (0.41 mg/L). These fungal-derived adsorbents exhibited comparable structural properties and Pb(II) removal performance. Their combination of high adsorption capacity, rapid kinetics, selectivity and simple synthesis underscores strong potential for practical remediation of heavy-metal-polluted surface waters.