Fully exposed silver nanoparticles stabilized on pH-responsive lignin-reactors for enhanced 4-nitrophenol reduction

• Published in: Journal of environmental chemical engineering 2022-06, Vol.10 (3), p.107945, Article 107945
• Main Authors: Xiao, Wen-Zhe, Xiao, Ling-Ping, Yang, Yue-Qin, Xu, Qian, He, Wen-Qing, Zhang, Jia, Wang, Ruo-Yan, Zhao, Xin, Zhai, Shang-Ru, Sun, Run-Cang
• Format: Article
• Language: English
• Subjects: 4-Aminophenol; 4-Nitrophenol; Catalytic reduction; Hydrogenation; Lignin; Silver nanoparticles
• ISSN: 2213-3437; 2213-3437
• DOI: 10.1016/j.jece.2022.107945

Lignin as an advanced catalyst support has attracted much attention owing to its sufficient functional groups and natural cross-linked network structure, as well as good biodegradability. Herein, we fabricate a pair of lignin-reactors with silver nanoparticles (Ag NPs) supported outside or embedded in pre-hydrolyzed lignin (designated as Ag/PL or Ag@PL, respectively) via the self-assembly approach, which could be used for efficient catalytic reduction of 4-nitrophenol (4-NP). Through this strategy, the phase transitions and morphology changes of reactors could be achieved based on the pH responsiveness of lignin. The resultant Ag/PL exhibits a much higher catalytic activity (TOF 5.2 × 103 h−1, k 4.8 × 10−2 s−1) as compared to that of Ag@PL (TOF 2.5 × 103 h−1, k 2.3 × 10−2 s−1) under a low NaBH4 concentration (n[NaBH4]/n[4-NP], 100) at room temperature, which notably surpasses those of previously reported carbon-supported catalysts. The enhanced catalytic performance of Ag/PL is attributed to the fact that the fully exposed Ag NPs on the interface possess close proximity to the reactant. This work not only provides a promising route to design advanced catalysts in wastewater treatment system, but also paves the way for lignin valorization into functional-materials. [Display omitted] •Facile synthesis of lignin-reactors based on pH responsiveness of lignin.•Fully exposed Ag NPs with high accessibility anchored over the lignin support.•Ag/PL exhibited super catalytic reactivity toward 4-NP reduction than that of Ag@PL.•Ag/PL catalyst showed a TOF value up to 5.2 × 103 h−1.