Valorization of chicken bone waste into biochar adsorbent for methyl red adsorption from aqueous systems

The sustainable valorization of poultry by-products into functional materials offers an eco-friendly approach for wastewater remediation and waste management. In this work, chicken bone waste (CBW) was converted into biochar (CBWB) via controlled pyrolysis for 2 h at 750 °C and examined as a low-cost adsorbent for the uptake of methyl red (MR) dye from aqueous solutions. The physicochemical characteristics of CBW and CBWB were evaluated using Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) surface area analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Pyrolysis greatly improved porosity and surface area, increasing the BET surface area from 37.3 m²/g for CBW to 76.4 m²/g for CBWB. Batch sorption studies examined the impacts of solution pH, initial dye concentration, adsorbent dosage, contact time, and temperature on MR elimination. Adsorption kinetics followed the pseudo-first-order model for CBW and the pseudo-second-order model for CBWB, signifying stronger surface interactions after pyrolysis. Equilibrium data were best explained by the Langmuir isotherm for CBW and the Freundlich isotherm for CBWB, with maximum adsorption capacities of 84.84 and 138.58 mg/g, respectively. Thermodynamic assessment confirmed that the adsorption process was spontaneous and endothermic. Regeneration studies showed that CBWB reserved approximately 69% of its initial adsorption efficiency after five cycles of operation. These findings revealed that chicken bone waste-derived biochar is reusable, efficient, and sustainable adsorbent for dye-contaminated wastewater treatment.