Detection and removal of Cr(VI) ions in aqueous solutions via acrylamide-functionalized wool fibers

The design of environmentally friendly and cost-efficient materials for the detection and elimination of heavy metals is crucial for mitigating pollution in natural water bodies. This study presents the grafting of acrylamide onto wool fibers through a thiol-ene chemistry (referred to as Wool-AM), aimed at detecting and removing of wastewater containing hexavalent chromium (Cr(VI)) ions. Fluorescence experiments demonstrated that Wool-AM exhibits excellent fluorescence stability across varying pH levels and salt concentrations. It also displayed selective affinity for Cr(VI), excellent selectivity, and a low detection limit of 2.51 µmol/L. Batch adsorption experiments indicated that the adsorption process of Wool-AM conforms to the pseudo-second-order kinetic model, and the adsorption isotherm of Cr(VI) ion is predominantly a chemical process. Under the conditions of 25 °C and pH 5.5, the Langmuir model estimates that Wool-AM can adsorb 112.36 mg/g of Cr(VI) ions. The study further explored the pH, adsorbent dosage (g/L), adsorption time (t), Cr(III) concentration (C₀), coexisting ions, and reusability, elucidating the related adsorption mechanisms. Environmental toxicity assessments revealed that Wool-AM poses minimal adverse effects on the environment. Additionally, the adsorption-reduction-precipitation method effectively concentrated Cr(VI) ions from simulated electroplating wastewater, converting it into pure Cr₂O₃ products (98.02 %). In summary, this approach successfully achieves the detection, adsorption, and conversion of Cr(VI) to Cr(III). This study provides an efficient, green, and sustainable strategy for detection and recovery of Cr(VI) ions in aqueous.