Facile synthesis of metal ion-cross-linked alginate electrode for efficient organic dye removal

Abstract

The metal ion (M = Co2+, Fe3+, and Cu2+)-cross-linked alginate electrodes (MCLAEs) were prepared by a simple mixing and gelling process as the novel gel electrode for organic dye removal. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Fourier transform infrared (FTIR) spectroscopy, and tensile strength (TS) tests were used to characterize the MCLAEs. The electrochemical characterization of the MCLAEs was performed using cyclic voltammetry (CV). Moreover, the electrochemical performances of the MCLAEs were analyzed using acid orange and basic orange and the results indicated that the reduction processes between the MCLAEs and the dyes were irreversible. The influence of the scan rate and the initial pH value on the electrochemical behavior of the MCLAEs in the CV were also investigated; the linear relationship between the square root of the scan rates and the cathodic peak current implied a diffusion-controlled reaction between the MLACEs and the dyes as the scan rate increased from 20 to 500 mV s−1. Additionally, in the pH value range of 3.0 to 7.0, the current of the cathodic peaks reached the maximum value at pH 3.0; whereas, the cathodic peak current was almost the same at all other pH values. The result illustrated that the pH value has a similar effect on the reduction process at pH values in the range of 4.0 to 7.0. The findings of this study elucidated that the as-prepared MCLAEs were effective gel electrode for the removal of dyes from wastewater.