Waste valorization strategy: Fabrication of high-efficiency magnetic ultrafine cattle hair powder and its adsorption performance on acid dye

To address the environmental issues caused by the accumulation of large amounts of animal hair generated during the leather production process, this study mechanically milled cattle hair waste (CHW) into ultrafine cattle hair powder (UCP), and a magnetic cattle hair powder adsorbent material (MUCP) was synthesized through an in-situ generation method using FeSO 4 ·7 H 2 O and FeCl 3 ·6 H 2 O as sources. Adsorption experiments were conducted under various conditions to investigate the adsorption performance of MUCP for acid dye. The results showed that lower pH levels led to higher dye removal rates. When the pH was 2, the dye removal rate reached 93.1 %. The adsorption process was consistent with the pseudo-second-order kinetics model and the Langmuir isotherm model. When 0.1 g of MUCP-8 was used to adsorb the dye solution with an initial concentration of 500 mg·L −1 , pH 3, 45 ℃, and a duration time of 48 h, the maximum adsorption capacity was 699.30 mg·g −1 . The adsorption mechanism of MUCP for acid dye mainly involved void filling, hydrogen bonding, and electrostatic attraction between protonated amino groups and negatively charged dye ions. MUCP has superparamagnetic properties, allowing easy and quick separation and recovery from the mixed solution under an external magnetic field after dye adsorption. This provides a new solution for bio-based adsorbent materials with magnetic properties in dye wastewater treatment and waste-to-resource methods.