Polyethylenimine modified potassium tungsten oxide adsorbent for highly efficient Ag+ removal and valuable Ag0 recovery

Qi-Su Huang; Wei Wu; Wei Wei; Bing-Jie Ni

doi:10.1016/j.scitotenv.2019.07.328

Polyethylenimine modified potassium tungsten oxide adsorbent for highly efficient Ag⁺ removal and valuable Ag⁰ recovery

Sci Total Environ. 2019 Nov 20:692:1048-1056. doi: 10.1016/j.scitotenv.2019.07.328. Epub 2019 Jul 21.

Authors

Qi-Su Huang¹, Wei Wu¹, Wei Wei², Bing-Jie Ni³

Affiliations

¹ State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
² State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China. Electronic address: hitvivi@126.com.
³ State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China. Electronic address: bjni@tongji.edu.cn.

PMID: 31539937
DOI: 10.1016/j.scitotenv.2019.07.328

Abstract

Elemental Ag⁰ is well known for its remarkable catalytic and antibacterial properties, thus the regeneration of valuable Ag⁰ metal from Ag⁺ wastewater is of great significance. In this study, a novel polyethylenimine (PEI) modified potassium tungsten oxide (N-K₂W₄O₁₃) adsorbent was prepared for Ag⁺ removal and reduction to Ag⁰ using glutaraldehyde as crosslinking agent. XPS and FT-IR spectra verified PEI successfully anchored on the surface O and W atoms of K₂W₄O₁₃ through aldehyde bridges. The content of PEI in N-K₂W₄O₁₃ was calculated as 8.74wt% by TG curve. A heterogeneous PEI coating was observed in the SEM and TEM images. The N-K₂W₄O₁₃ exhibited larger Ag⁺ uptake (48.25mg/g) than the raw K₂W₄O₁₃ (42.50mg/g) though required a longer equilibrium time. This was due to the combined results of strong chelation and weak electrostatic repulsion that meanwhile occurring on the positive-charged surface of N-K₂W₄O₁₃. The maximum Ag⁺ uptake on N-K₂W₄O₁₃ was 72.5mg/g, which was larger than many of the reported adsorbents. Furthermore, the prepared N-K₂W₄O₁₃ displayed good anti-interference toward background ions (Na⁺, K⁺) and hold a stable Ag⁺ removal (>95%) after five runs of recycling tests. The mechanism studies elucidated that NH/N groups from the PEI modified N-K₂W₄O₁₃ mainly accounted for the Ag⁺ adsorption and Ag⁰ recovery in the adsorption-reduction process. Ion-exchange between Ag⁺ and K⁺ from the N-K₂W₄O₁₃ lattice also occurred. This work provided a facile method to synthesize a promising adsorbent for Ag⁺ wastewater remediation and valuable Ag⁰ recovery.

Keywords: Adsorption; Polyethylenimine (PEI); Potassium tungsten oxide (K(2)W(4)O(13)); Reduction; Removal; Sliver.