Magnetically Recyclable Wool Keratin Modified Magnetite Powders for Efficient Removal of Cu2+ Ions from Aqueous Solutions

Xinyue Zhang; Yani Guo; Wenjun Li; Jinyuan Zhang; Hailiang Wu; Ningtao Mao; Hui Zhang

doi:10.3390/nano11051068

Magnetically Recyclable Wool Keratin Modified Magnetite Powders for Efficient Removal of Cu²⁺ Ions from Aqueous Solutions

Nanomaterials (Basel). 2021 Apr 21;11(5):1068. doi: 10.3390/nano11051068.

Authors

Xinyue Zhang^{1

2}, Yani Guo¹, Wenjun Li^{2

3}, Jinyuan Zhang^{2

3}, Hailiang Wu³, Ningtao Mao⁴, Hui Zhang^{2

3}

Affiliations

¹ School of Environmental and Chemical Engineering, Xi'an Polytechnic University, Xi'an, Shaanxi 710048, China.
² Research Centre for Functional Textile Materials, School of Textile Science and Engineering, Xi'an Polytechnic University, Xi'an, Shaanxi 710048, China.
³ Key Laboratory of Functional Textile Material and Product, Xi'an Polytechnic University, Ministry of Education, Xi'an, Shaanxi 710048, China.
⁴ Performance Textiles and Clothing Research Group, School of Design, University of Leeds, Leeds LS2 9JT, UK.

Abstract

The treatment of wastewater containing heavy metals and the utilization of wool waste are very important for the sustainable development of textile mills. In this study, the wool keratin modified magnetite (Fe₃O₄) powders were fabricated by using wool waste via a co-precipitation technique for removal of Cu²⁺ ions from aqueous solutions. The morphology, chemical compositions, crystal structure, microstructure, magnetism properties, organic content, and specific surface area of as-fabricated powders were systematically characterized by various techniques including field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM), thermogravimetric (TG) analysis, and Brunauer-Emmett-Teller (BET) surface area analyzer. The effects of experimental parameters such as the volume of wool keratin hydrolysate, the dosage of powder, the initial Cu²⁺ ion concentration, and the pH value of solution on the adsorption capacity of Cu²⁺ ions by the powders were examined. The experimental results indicated that the Cu²⁺ ion adsorption performance of the wool keratin modified Fe₃O₄ powders exhibited much better than that of the chitosan modified ones with a maximum Cu²⁺ adsorption capacity of 27.4 mg/g under favorable conditions (0.05 g powders; 50 mL of 40 mg/L CuSO₄; pH 5; temperature 293 K). The high adsorption capacity towards Cu²⁺ ions on the wool keratin modified Fe₃O₄ powders was primarily because of the strong surface complexation of -COOH and -NH₂ functional groups of wool keratins with Cu²⁺ ions. The Cu²⁺ ion adsorption process on the wool keratin modified Fe₃O₄ powders followed the Temkin adsorption isotherm model and the intraparticle diffusion and pseudo-second-order adsorption kinetic models. After Cu²⁺ ion removal, the wool keratin modified Fe₃O₄ powders were easily separated using a magnet from aqueous solution and efficiently regenerated using 0.5 M ethylene diamine tetraacetic acid (EDTA)-H₂SO₄ eluting. The wool keratin modified Fe₃O₄ powders possessed good regenerative performance after five cycles. This study provided a feasible way to utilize waste wool textiles for preparing magnetic biomass-based adsorbents for the removal of heavy metal ions from aqueous solutions.

Keywords: Cu2+ ions; adsorption; magnetite (Fe3O4); wool keratin.

Grants and funding

51873169/National Natural Science Foundation of China