Removal of Noble Metal Ions (Ag⁺) by Mercapto Group-Containing Polypyrrole Matrix and Reusability of Its Waste Material in Environmental Applications

Abstract

A novel approach was introduced to remove metal (Ag+) ions from aqueous solution and subsequently restate the metal-loaded materials for a number of environmentally friendly applications. A versatile adsorbent, polypyrrole with mercapto-functionalized chelating groups (PPy/MAA), successfully adsorbed Ag+ ions through subsequent reduction to silver nanoparticles (Ag0 NPs) into the composite matrix. The as-prepared composite (PPy/MAA) and Ag-adsorbed PPy/MAA (PPy/MAA/Ag0) were fully characterized by FE-SEM, EDS, HR-(S)­TEM, XRD, FTIR, BET, XPS, and zeta potential measurements. Batch adsorption results showed that the adsorption process can be explained well by a pseudo-second-order model. The maximum adsorption capacity calculated using a Langmuir isotherm model was 714.28 mg/g at 25 °C. XRD, XPS, and HR-TEM analyses confirmed the presence of metallic silver nanoparticles on the surface of the composite matrix after the in situ reduction of Ag+ to Ag0. Among the applications tested, the metal-loaded waste (PPy/MAA/Ag0) was found to have antimicrobial activity, as it inhibited the growth of Escherichia coli, while pure adsorbent without silver showed no killing effect toward E. coli. PPy/MAA/Ag0 also played an important role in the catalytic reduction of 4-nitrophenol and also exhibited good sensitivity to NO2 in gas-sensing applications. Therefore, the developed PPy/MAA composite achieved 2-fold environmental benefits, not only remediating Ag+ from polluted waterways but also opening a new window for subsequently acting as an agent for antibacterial ability, catalytic activity, and gas-sensing efficiencies.

Highly efficient adsorption of Ag(I) from aqueous solution by Zn‐NDC metal–organic framework

“…The slow increase may be ascribed to the fewer active sites of the adsorbent along with the prolonging of the uptake time. [ 30 ]…”

“…The slow increase may be ascribed to the fewer active sites of the adsorbent along with the prolonging of the uptake time. [30] Generally, the kinetic experimental data were fitted with kinetic models, namely, pseudo-first-order, pseudo-second-order, and Elovich kinetic models (Equations S1-S3).…”

Nanostructured Materials for Water Purification: Adsorption of Heavy Metal Ions and Organic Dyes

“…It is essential to mitigate this problem sustainably. It may be solved by reusing spent materials in various applications, including catalysis, sensors, and energy applications [ 251 , 252 ]. Future study will be required to add value to secondary toxic waste through recyclability and circular strategy.…”

Review on the Use of Heavy Metal Deposits from Water Treatment Waste towards Catalytic Chemical Syntheses

“…After that, the prepared nanoparticle-decorated composites were successfully applied in antimicrobial activity, catalytic reduction of 4-NP, and NO 2 gas detection. The synthesized PPy/MAA/Ag 0 composites exhibited excellent activity in all applications mentioned above [179]. Das et al, in prepared thiol-functionalized polypyrrole (PPy/MAA) composite, and used it for the absorption of highly toxic Hg(II) from the waste industrial effluent.…”