Silica-integrated chemically modified human hair waste: A novel nanocomposite for efficient removal of methylene blue dye from water

This study introduces silica-modified human hair (HH-SiO₂), a novel nanocomposite synthesized from chemically modified human hair waste integrated with silica, for efficient methylene blue (MB) dye removal from water. Comprehensive characterization confirmed its structure and functionality. FTIR and XRD analyses revealed the successful incorporation of sulfonic acid groups and silica, with a broad XRD peak indicating its amorphous nature. XPS confirmed the presence of Si, S, N, C, and O, validating the composite's structural integrity, while TGA demonstrated its thermal stability up to 600 °C. SEM imaging highlighted its hierarchical structure, high surface area, and enhanced porosity due to silica integration. Adsorption studies showed optimal performance at pH 8, with removal efficiency of 95–98 % and a maximum adsorption capacity of 126.6 mg/g. The nanocomposite achieved equilibrium within 200 min, with kinetics most accurately represented by the pseudo-second-order model, suggesting chemisorption as the rate-limiting step. Adsorption isotherms followed the Langmuir model, suggesting monolayer adsorption on a homogeneous surface. Thermodynamic analysis revealed a spontaneous and exothermic process, favoring lower temperatures, with negative ΔG° and ΔH° values. Regeneration experiments demonstrated excellent reusability, with acetic acid achieving a desorption efficiency of approximately 90 %. These findings highlight HH-SiO₂’s potential as a sustainable and efficient adsorbent for water purification, leveraging renewable resources and advanced nanocomposite design to address environmental remediation challenges.