Sustainable gliadin - Metal oxide composites for efficient inactivation of Escherichia coli and remediation of cobalt (II) from water

Abstract

Bio-based materials facilitate greener approach to engineering novel materials with multifunctional properties for various applications, including water treatment. In this study, we extracted gliadin from wheat gluten using alcoholic solvent. The aggregation limitations of gliadin protein were overcome by functionalization with metal oxides (MOs) TiO2, AgFe2O3, and AgFe-TiO2 prepared by chemical precipitations. The novel composites were characterised by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), thermogravimetry analysis (TGA), Brunauer Emmet-Teller (BET), and zeta potential. The multifunctionality of MOs-gliadin composites was tested through toxic Escherichia coli (E. coli) inactivation and Co2+ adsorption from water. The antibacterial results showed excellent inhibition under both dark and light conditions. The maximum Co2+ uptake of 101 mg/g was reached with TiO2@gliadin after 24 h and best fitted the Langmuir isotherm model. The adsorption process followed pseudo-second-order model with an equilibrium adsorption capacity, qe2 = 89.86 mg/g, closer to the experimental data. Thermodynamic investigations indicated that ΔG◦ = − 9.677 kJ/mol, ΔH◦ = − 123 kJ/mol, and ΔS◦ = 0.490 J.K./mol, respectively, suggesting that adsorption was spontaneous and endothermic. The The regenerated TiO2@gliadin composite was still efficient after five consecutive cycles. This study demonstrates that MOs-gliadin-blend composites are sustainable for water purification.