High-Performance Hg(II) Removal Using Thiol-Functionalized Polypyrrole (PPy/MAA) Composite and Effective Catalytic Activity of Hg(II)-Adsorbed Waste Material

Abstract

Problems related with highly toxic mercury emissions from industrial effluents are one of the great concerns in the world of environmental science and technology. The primary aim of this present work is the remediation of hazardous pollutant Hg (II) from aqueous medium via a thiol-functionalized (mercaptoacetic acid) conducting polypyrrole (PPy/MAA) composite. The synthesized composite exhibited high Hg(II) adsorption capacity as the incorporated mercapto functionality plays a vital role for the strong binding affinity toward Hg(II) ions. To understand the adsorption properties of the developed polymer composite, a series of batch adsorption experiments were performed by altering the adsorption parameters. A maximum adsorption capacity (qmax) of 1736.8 mg/g at 25 °C was obtained using the Langmuir isotherm. The adsorption data showed better fitting to the pseudo-second-order rate equation for Hg(II) adsorption. A plausible adsorption mechanism is suggested on the basis of XPS results of major elements present in the adsorbent. To apply to catalytic reactions, the use of waste-derived mercury-adsorbed material (termed as PPy-MAA/Hg (II)) is also addressed here for further application of organic transformation. Here, we described the catalytic reaction with phenylacetylene in the presence of 5 mol % PPy-MAA/Hg (II) catalyst at 90 °C for 6 h. This method provides a straightforward formation of acetophenone in 55% yield. Thus, PPy/MAA not only effectively eliminates toxic Hg(II) ions from water but also is successfully applied for the catalytic organic transformation after adsorption.