Scalable production of steam-activated wool carbon for highly efficient Cr(VI) adsorption

This study presents a sustainable approach for converting waste sheep wool into high-performance activated carbon for Cr(VI) removal from aqueous solutions. Chemical (NaOH) and steam activation routes were evaluated, and steam activation at ۹۰۰ °C for ۳ h in a rotary furnace produced the optimal material. The resulting carbon exhibited a high specific surface area (۱۸۰۷ m²/g), a pore volume of ۱.۰۰۲ cm³/g, and a well-developed micro-mesoporous structure. The optimized adsorbent achieved ۹۹% removal of Cr(VI) from a ۴۰۰ mg/L solution within ۴۵ min. Physicochemical characterization (BET, SEM, XRD, Raman) and adsorption analysis (ICP-OES) confirmed the material’s suitability for adsorption processes. Equilibrium behavior was best described by the Freundlich isotherm (R² = ۰.۹۷۶), while the Langmuir model yielded a monolayer capacity of ۱۴۷ mg/g. Kinetic data closely followed the pseudo-second-order model (R² = ۰.۹۹۹), suggesting adsorption dominated by electrostatic interactions and surface complexation under acidic conditions. These findings demonstrate that wool waste can be effectively valorized as a low-cost, scalable, and efficient adsorbent for Cr(VI) remediation.

Keywords:

Activated carbon , Steam activation , Chromium (VI) removal , Wool waste , Wastewater treatment