Remarkable Acid Stability of Polypyrrole‐MoS₄: A Highly Selective and Efficient Scavenger of Heavy Metals Over a Wide pH Range

Abstract

Abstract The new material polypyrrole/MoS 4 2− (MoS 4 ‐Ppy), prepared by ion‐exchange of NO 3 ‐ of NO 3 ‐Ppy with MoS 4 2− , displays high acid stability and excellent uptake for heavy metal ions such as Hg 2+ , Ag + , Cu 2+ , and Pb 2+ . The different maximum adsorption capacities ( q m ) for Cu 2+ , Pb 2+ , Hg 2+ , and Ag + depend on the various binding modes arising from the different thiophilicity of these metal ions. The removals of Ag + and Pb 2+ reach >99.6% within 5 min, and for highly toxic Hg 2+ , >98% removal achieves at 1 min. At strong acid limit, the exceptional q m (Ag + ) of 725 mg g −1 places the MoS 4 ‐Ppy at the top of materials for such removal. Uptake kinetics of Ag + , Hg 2+ , and Pb 2+ is extremely fast: >99.9% removal rates at wide pH range (0.5–6) within 1–5 min. Also, at strongly acidic conditions (pH ≈ 1), for highly toxic Hg 2+ , <2 ppb concentration can be achieved, accepted as safe limit. The MoS 4 ‐Ppy demonstrates an outstanding ability to separate low‐concentrated Ag + from high concentrated Cu 2+ especially under strong acidic conditions (pH ≈ 1), showing a large separation factor SF Ag/Cu ( K d Ag / K d Cu ) of 10 5 (>100). MoS 4 ‐Ppy is a superior and novel sorbent material for water remediation applications as well as precious metals recovery.