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

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.

Keratin-derived sorbents for efficient removal of copper ions from aqueous solutions

“…Comparisons of the Cu( ii ) adsorption capacities of other keratins derived adsorbents reported elsewhere were obtained (Table 3). 19,26,28,42–44 The adsorption performance of HK/DAA was higher than those of other keratin composites, suggesting its potential for the removal of Cu( ii ) from wastewater. Based on the above consideration, that is possibly because of the synergic effect of high surface area and coordinate ability of HK/DAA.…”

“…17,18 Protein-based materials such as keratin have been applied to remove copper ions from the solution. 19,20…”

“…Although effort has been made to generate adsorbents using feather keratin and its derivatives to expunge Cu( ii ) from water, 19,20,26–29 more experiments are needed to expand the application of keratin-derived materials in metal ion removal from the wastewater. To improve the efficiency, the integration of specific functional groups with potent coordination capabilities into an adsorbent can significantly enhance its targeted adsorption performance.…”

Study on plasma‐modified corn stover‐humic acid‐based superabsorbent resin

“…The pseudo‐second‐order kinetic model assumed in the theoretical case that the chemisorption process is caused by the interaction of the adsorbent and the adsorbent mass. It is expressed by Equation (): 4,28,29 where k 2 is the adsorption rate constant of the pseudo‐second‐order kinetic model (min −1 ). Figure 8b and Table 1 show that the correlation coefficient of the pseudo‐second‐order kinetic model is 0.99381, and the q e ,cal of the resin was close to the q e ,exp of 1191.62242 g/g.…”