Adsorptive removal of phosphate with waste wool derivatives: A preliminary research

The textile industry is a pillar of the manufacturing sector worldwide, but it still represents a significantly polluting production sector since it is energy-, water- and natural resources-intensive. Herein, we recovered waste wool that does not meet the technical requirements to be used for yarns and fabrics to prepare materials for wastewater remediation. The wool underwent an alkaline treatment, eventually saturated with FeCl3 and then left at RT or heated at 180 °C to induce crosslinking/stabilization. The materials were characterized by SEM, TGA, DSC, FT-IR and water uptake tests. The main findings concern the impact of alkaline treatment on morphology and crystalline structure; additionally, the samples with iron displayed a behavior attributable to a crosslinking effect operated by Fe3+. Preliminary batch adsorption experiments were performed with five samples: bare wool (S1), S_Wool_NaOH (S2), S_Wool_NaOH_180 (S3), S_Wool_Fe_NaOH (S4) and S_Wool_Fe_NaOH_180 (S5). Samples 1, 2 and 3 showed to be inefficient in phosphate removal, so further batch experiments were carried out only for S4 and S5. Investigated samples showed similar adsorbed amounts of 16.653 and 16.902 mg/g, respectively, at the initial phosphate concentration of 20 mg/L. A high removal percentage was obtained in a wide pH spectrum - from 3 to 10. Results suggest that the proposed Fe-added adsorbents have the potential for phosphate removal from wastewater.