Adsorption Studies on Ag(I) Using Poly(N-phenylglycine) Membrane and Application in Practical Silver Recycling

Abstract

Adsorption methods offer advantages in the treatment of polluted water, particularly with the removal of heavy metal ions, because they are simple in process and no secondary pollutants are involved. Conductive polymers are good adsorbents because of their diverse functional groups and large, active surface areas. Poly­(N-phenylglycine) (PNPG) is an emerging conductive polymer used in adsorption studies. In this study, a PNPG membrane was prepared by vacuum filtration, and characterization studies were performed to elucidate the reaction mechanism between the PNPG membrane and Ag­(I). It was found that most benzenoid diamine structures undergo a redox reaction with Ag­(I), while a minority undergo chelation. Through studies on the pH influence, adsorption kinetics, and adsorption isotherms, this adsorption process fits the pseudo-second-order and Langmuir models which indicate chemical adsorption and monolayer adsorption. The maximum Ag­(I) adsorption capacity of the PNPG membrane, 366 mg g–1, was also close to the theoretically calculated value at pH 6. In addition, the PNPG membrane showed potential for the recovery of Ag from real solutions when leaching solutions of e-waste and municipal solid waste incineration fly ash were subjected to adsorption experiments.

Recovery of Ag(I) from Wastewater by Adsorption: Status and Challenges

“…For example, Xue et al [26] reported on the composite metal-organic framework material (MIL−127/26 PoPD), demonstrating notable selectivity for extracting Ag(I) ions from seawater obtained from two distinct geographical regions, as well as from leachates derived from sensor contact points and waste photographic fixer solutions. Wu et al [119] utilized the conductive polymer Poly(N−phenylglycine) (PNPG) to prepare a novel PNPG membrane via vacuum filtration for Ag(I) recovery from two practical solutions (waste PCB leachate and municipal solid waste incineration ash digestion solution). Despite the harsh environments of the actual solutions, PNPG still adsorbed approximately 96% of Ag(I).…”

Efficient Decolorization of Anionic Dye (Methyl Blue) by Natural-Based Biosorbent (nano-Magnetic Sophora Japonica Fruit Seed Biochar)

“…Considering whether biosorbents can be reused is important in determining the adsorption mechanism. In the experiment, 0.1 mol/L diluted HCl was used as a desorption agent to examine the reuse of biosorbents (Ghaedi et al 2022, Wu et al 2022. The biosorbent still has a high adsorption efficiency after three cycles (respectively 92.0 %, 91.2%, 90.1% removal).…”