Sustainable valorization of poultry waste through optimized keratin extraction and its prospective use in dye adsorption

Chicken feathers (CFs) are an important by-product of the poultry industry, accounting for 4–6% of the total weight of the chicken. CFs pose serious environmental problems because of traditional disposal methods like incineration and landfilling. CFs are rich in keratin and can be used as a biopolymer for various applications, such as wastewater treatment. The present study optimized keratin extraction by Box-Behnken Design (BBD), evaluating the effects of temperature, time, and reducing agent concentration to maximize the yield. Characterization via Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Thermogravimetric analysis (TGA) confirmed preserved protein structure, semicrystalline nature and thermal stability. Keratin beads (KBs) were fabricated for the removal of Congo Red (CR) from aqueous solutions. Batch adsorption studies investigated pH, adsorbent dosage, contact time, and initial dye concentration, achieving removal efficiencies of ~80%. Kinetics followed the pseudo-second-order model (R 2 = 0.9974), indicating the primary role of chemisorption. Equilibrium data fitted the Freundlich isotherm better than the Langmuir (R 2 = 0.9991), which implies that the process is heterogeneous multilayer adsorption, while the Langmuir model estimated a maximal adsorption capacity of 81.3 mg/g. This study supports the United Nations Sustainable Development Goals (SDGs), particularly SDG 6, SDG 12 and SDG 13, by offering a scalable, eco-friendly solution for wastewater treatment while contributing to sustainable waste management practices.