Advanced Cd (II) adsorbent fabricated with hordein from barley (Hordeum vulgare L.) via electrospinning technology

Hordein, as the by-product in beer brewing, was evaluated to produce nanofiber for Cd (II) removal through the electrospinning technology. This method provided the advantages of low cost, convenience, and sustainability. Incorporation of N, N'-methylenebisacrylamide (MBA) improved the Cd (II) adsorption capacity. SEM results showed that the diameter of the hordein/MBA electrospun nanofiber (HMENF) decreased with the addition of MBA, and the bead-free nanofiber was obtained within the content of 30 % MBA (w/w). ATR-FTIR and XRD analysis confirmed that crosslinking between MBA and hordein occurred. Results showed that the HMENF membrane had optimal adsorption at pH 5-6, 160 mg/L initial Cd (II) concentration, and 10 h contact time. Fundamental adsorption properties were evaluated with the adsorption kinetics and adsorption isotherm. The adsorption data fitted well with the pseudo-second-order (PSO) model and the Langmuir isotherm model. The maximum adsorption capacity was calculated to be 48.78 mg/g. High-level Cd (II) adsorption capacity remained even after 5 recycling processes. Moreover, the adsorption capacity and mechanism were compared and proposed. All the results above revealed that the novel HMENF membrane was a promising adsorbent in the application of Cd (II) contained wastewater treatment.