Green Nanoengineered Keratin Derived Bio-Adsorbent for Heavy Metals Removal from Aqueous Media

Abstract

Exploiting poultry chicken feathers, a keratin-rich by-product offers a sustainable raw material for bio-adsorbents in water remediation. This study developed a bio-adsorbent from chicken feathers keratin (CFK), functionalized with surface-modified graphene oxide (SMGO). The bio-adsorbent was tested for adsorbing metal cations (Pb, Cd, Ni, Zn, Co) and oxyanions (As, Se, Cr) from water contaminated with 600 µg/L of each metal at pH 5.5, 7.5, and 10.5. Results showed optimal removal efficiencies at pH 7.5, with anions achieving ≥91.10% for As (III), ≥89.55% for Cr (VI), and ≥74.33% for Se (IV). Cations removal reached 96.34% for Co (II), 97.36% for Ni (II), 99.03% for Cd (II), 99.21% for Pb (II), and 59.06% for Zn (II). Kinetic studies indicated rapid initial uptake within the first 6 hours, reaching equilibrium at 24 hours. The bio-adsorbent maintained high adsorption capacities over four regeneration cycles with minimal efficiency loss, showing strong stability and reusability. Removal efficiency followed the order: Pb (II) 〉 Cd (II) 〉 Ni (II) 〉 Co (II) 〉 Zn (II), correlating with their ionic radii. Ni²⁺ adsorbed more effectively than Co²⁺ due to a smaller ionic radius and stronger electrostatic attraction. These findings highlight CFK-SMGO's efficacy in wastewater treatment, promoting bio-based sustainable adsorbents.