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

Linxia Xie; Zihuan Yu; Saiful M. Islam; Keren Shi; Yahan Cheng; Mengwei Yuan; Jing Zhao; Genban Sun; Huifeng Li; Shulan Ma; Mercouri G. Kanatzidis

Index: 10.1002/adfm.201800502

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Abstract

The new material polypyrrole/MoS42−(MoS4‐Ppy), prepared by ion‐exchange of NO3‐ of NO3‐Ppy with MoS42−, displays high acid stability and excellent uptake for heavy metal ions such as Hg2+, Ag+, Cu2+, and Pb2+. The different maximum adsorption capacities (qm) for Cu2+, Pb2+, Hg2+, and Ag+ depend on the various binding modes arising from the different thiophilicity of these metal ions. The removals of Ag+ and Pb2+ reach >99.6% within 5 min, and for highly toxic Hg2+, >98% removal achieves at 1 min. At strong acid limit, the exceptional qm(Ag+) of 725 mg g−1 places the MoS4‐Ppy at the top of materials for such removal. Uptake kinetics of Ag+, Hg2+, and Pb2+ 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 Hg2+, <2 ppb concentration can be achieved, accepted as safe limit. The MoS4‐Ppy demonstrates an outstanding ability to separate low‐concentrated Ag+ from high concentrated Cu2+ especially under strong acidic conditions (pH ≈ 1), showing a large separation factor SFAg/Cu (KdAg/KdCu) of 105 (>100). MoS4‐Ppy is a superior and novel sorbent material for water remediation applications as well as precious metals recovery.