Evaluating adsorption media for simultaneous removal of arsenate and cadmium from metallurgical wastewater

Abstract

With the wide application of adsorption technology for the remediation of heavy metal contaminated metallurgical wastewater, selecting appropriate adsorbent media is a prerequisite for advancement. In this study, four commonly used adsorbents including titanium dioxide (TiO2), granular ferric oxide (GFO), activated alumina (AA), and nanoscale zero-valent iron (nZVI) were systematically evaluated for their abilities to simultaneously remove arsenate [As(V)] and cadmium (Cd) from wastewater. In kinetics and dosage experiments, TiO2 and GFO adsorbed more As(V) and Cd than AA and nZVI, which suggests that these two are ideal candidates for the remediation of metal-contaminated wastewater. Furthermore, TiO2 and GFO exhibited a wider pH application range than AA and nZVI. The pH edge and dosage experimental results can be well described using the CD-MUSIC model under the EXAFS constraint. Finally, regeneration experiments demonstrated that only TiO2 exhibited high adsorption efficiency after regeneration, and its high chemical stability was further evidenced by in-situ XRD characterization. Our systematic comparisons of the four different media for As(V) and Cd adsorption demonstrate that TiO2 is an ideal adsorbent, which paves the way for further wastewater treatment.