Removal of arsenic from aqueous solution using microflower-like δ-Bi₂O₃ as adsorbent: adsorption characteristics and mechanisms

Abstract

Arsenic is one of the most common and harmful pollutants in environment, causing serious damage to human health and ecosystems. Herein, the uptake of arsenic by microflower-like δ-Bi₂O₃ including adsorption equilibrium, kinetics, desorption, the effects of initial pH and interfering ions on removal efficiency were studied in batch experiments, and the adsorption mechanism was also elucidated by Fourier transform infrared spectra and X-ray photoelectron spectroscopy. The results showed that the maximum adsorption capacities of As(III) and As(V) were 115.05 and 33.17 mg g⁻¹, respectively. Simultaneously, the arsenic removal by MF-δ-Bi₂O₃ could work well in a wide pH range of 4–11 and presented excellent sorption selectivity for arsenic in the presence of competitive anions (NO₃ ⁻ and SO₄ ^{2 −}). Furthermore, the adsorbent showed excellent morphological and structural stability after adsorption, which makes it easy to separate from aqueous solution and avoid secondary pollution as much as possible. The ligand exchange between arsenic ions and hydroxyl groups occupying the oxygen vacancies of MF-δ-Bi₂O₃ was the main adsorption mechanism. All studies in this experiment can led to a new direction for arsenic removal.

Graphical Abstract

Keywords:

• Arsenic
• microflower-like δ-Bi2O3
• adsorption
• stability
• ligand exchange

Additional information

Funding

National Natural Science Foundation of China (grant number 41771098).