Red mud (aluminum industrial waste): An eco-friendly treatment of electroplating effluent

Abstract

In this work, aluminum industrial waste, red mud (RM), was activated to verify its potential in the management of electroplating wastewater containing hexavalent chromium (Cr(VI)). A comparison between the adsorption capabilities of RM and activated red mud (ARM) towards Cr(VI) from aqueous solutions was made. The effects of several parameters were evaluated. The adsorbents were characterized by field emission scanning electron microscopy (FESEM), Fourier transmission infrared spectroscopy (FTIR), x-ray diffraction (XRD), zeta potential, and thermogravimetric analysis (TGA). The particle size was observed as 23.59 nm. The ARM demonstrated an acceptable adsorption capacity of 25.641 mg/g at a pH of 2, adsorbent dosage of 2 g/L, initial Cr(VI) concentration of 100 mg/L, at 25°C. The experimental data is in good agreement with Langmuir adsorption isotherm. The kinetic study was performed to verify that the adsorption follows pseudo-second-order kinetics. In addition, the ARM showed decent recyclability for adsorbing Cr(VI) as even after three adsorption cycles, and the adsorption capacity was reduced by ~30%. The results recommend ARM to be an efficient and cost-effective adsorbent for Cr(VI) removal from industrial wastewater.