Efficient removal of Cu(II) and Cr(III) contaminants from aqueous solutions using marble waste powder

Abstract

This study describes the evaluation of Brazilian powdered marble waste (MW) for the removal of Cr(III) or Cu(II) ions from aqueous solutions. The effects of various parameters, such as pH, initial Cr(III) and Cu(II) concentration and contact time were investigated for batch experiments. The adsorption kinetic, isotherms and thermodynamic of Cu(II) and Cr(III) on MW were also studied. Scanning electron microscopy, energy dispersive spectroscopy, Raman spectroscopy, and X-ray diffraction help us to characterize the material before and after the removal process. The results demonstrated that the isotherm data fit the Sips model, corresponding to the chemisorption and the probable non-reversibility of the process. The adsorption capacities were 222.84 mg g−1 for Cu(II) and 148.03 mg g−1 for Cr(III). The kinetic study showed that the Avrami rate equation better described the adsorption process for both ions. The intra-particle and film diffusion were the rate limiting steps and controlled adsorption process. Thermodynamic parameters suggested that both metal ions adsorption on MW was a spontaneous process. The characterization techniques confirmed that the material is majorly formed by calcite and dolomite, which presented a clear difference before and after the adsorption process. According to the results, metal ions removal seems to be controlled by both adsorption and precipitation onto the surface particles. It was observed that MW is an effective and alternative material in the uptake of Cu(II) and Cr(III) ions from aqueous medium due to great removal capacity as well as availability and low-cost.