Adsorption enhancement of Congo red dye from wastewater based on edamame shell originated activated carbon by the cations: Experimental and theoretical studies.

In this study, a microporous activated carbon (AC) with excellent performance was successfully prepared by KOH impregnation activation method using edamame shell as raw material. The synthesized AC with high specific surface area and pore volume can be effectively used for the adsorption and removal of Congo red (CR) from wastewater. Nitrogen adsorption isotherms, Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and zeta potential were used to characterize the structure of activated carbon. The ultra-high surface area and well-developed pore volume provided sufficient adsorption sites for CR adsorption, and the maximum adsorption effect of AC on CR was up to 1509.60 mg/g at 25 °C. The effects of pH, contact time, temperature and adsorbent mass on CR adsorption were investigated. In addition, the effects of different cations (Ca2+, Na+, K+, NH 4 +) on the CR adsorption of anionic dyes were focused by adding different concentrations (10 mM, 20 mM, 30 mM) of cations. The results showed that Ca2+, Na+ and K+ had a significant promotion effect on the CR adsorption of AC, among which Ca2+ had the most obvious promotion effect. Through model fitting, CR adsorption by AC conforms to Liu adsorption isotherm model and Elovich kinetic model. The results showed that the addition of cations could substantially improve the adsorption capacity of AC on the anionic dye CR, which has potential application in the field of dye wastewater treatment. [Display omitted] • Preparation of microporous activated carbon from agricultural waste edamame shells. • The prepared activated carbon has a large surface area(2653.382 m2·g−1) and pore volume(1.324 cm3·g−1). • The adsorption effect on CR can reach 1509.60 mg/g. • The effect of cations on the adsorption of anionic CR dyes by AC was studied. • Ca2+ can substantially increase the adsorption of the anionic dye CR by AC. [ABSTRACT FROM AUTHOR]