Hot‐Water‐Treated Eragrostis tef Grains as a Novel Biosorbent for Efficient Pb(II) Removal

ABSTRACT Hot‐water‐treated Eragrostis tef grains (HTG) were investigated as a biosorbent for Pb(II) removal from aqueous solutions. HTG was characterized using SEM‐EDX, elemental mapping, BET, FTIR, and pHpzc analyses. The material exhibited a heterogeneous meso/macroporous structure with a low surface area (3.69 m 2 /g) and oxygen‐ and nitrogen‐containing functional groups. The effects of pH, adsorbent dose, contact time, and temperature on Pb(II) removal were evaluated. The optimum conditions were pH 5, 0.25 g/L HTG dose, and 1440 min contact time, under which a Pb(II) removal efficiency of 99.66% ± 0.68% was achieved for a 10 mg/L solution. Equilibrium studies showed that the adsorption data were best described by the Langmuir isotherm model ( R 2 = 0.99), yielding a maximum adsorption capacity of 555.6 mg/g. Kinetic results followed the pseudo‐second‐order model, while D–R isotherm, FTIR, EDX, elemental mapping, and thermodynamic analyses suggested that Pb(II) uptake involved chemisorption‐related mechanisms, particularly ion exchange and surface complexation. Thermodynamic parameters (Δ H ° = −84.09 kJ/mol, Δ G ° < 0, Δ S ° < 0) indicated a spontaneous and exothermic process. Application to tap water and industrial wastewater demonstrated effective Pb(II) removal. The simple preparation procedure and low production cost highlight HTG as a promising biosorbent for Pb(II)‐contaminated waters.