Adsorption study of p -nitrophenol on a silver(I) triazolate MOF
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Adsorption study of p‑nitrophenol on a silver(I) triazolate MOF Huixia Miao1 · Shuya Song1 · Hao Chen1 · Wenhua Zhang1 · Runping Han1 · Guang Yang1
© Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract In this paper, the potential has been investigated of using the silver(I) 3,5-diphenyltriazolate MOF—AgTz-1 as an adsorbent towards the adsorption of p-nitrophenol (PNP) from water. Based on experimental results, the best adsorption performance can be achieved at room temperature (or slightly elevated temperature) in neutral solution with the adsorption capacity Q max being 184.8 mg/g (308 K) and 143.5 mg/g (298 K). The adsorption of PNP onto AgTz-1 is pH-dependent: at pH > 8 it can be described by the “one in, one out” anion exchange mechanism; while at pH 7 or less, some neutral 4-nitrophenol molecules may enter the interior of MOF along with 4-nitrophenolate anions via hydrogen-bonding and/or π-π stacking, accompanied by the expansion of MOF structure at higher equilibrium concentrations of PNP at 298 K and 308 K. Moreover, the adsorption efficiency of AgTz-1 remained almost the same after five consecutive cycles of adsorption–desorption. Keywords Adsorption · p-Nitrophenol · Anion exchange · MOF expansion · Hydrogen bonding
1 Introduction As a result of the wide use of p-nitrophenol (PNP) in textile, paper, plastics, medicine, explosives, and dyeing, etc. [1], many of these plants discharge wastewater with significant levels of PNP, which is unfortunately highly stable to light and oxidants or microbes in the environment and can exist in water for a long period of time. Due to its potent carcinogenic and teratogenic effects [2], PNP has been classified as a priority pollutant by the United States Environmental Protection Agency [3]. Effective removal of PNP from wastewater has been remaining one of the hotspots in wastewater treatment. The main methods for treating PNP include degradation, catalytic reduction and adsorption, etc. [4–6]. For example, the Rahimi-Nasrabadi’s group used N b2O5 or Ce2O3 doped Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10934-020-00917-w) contains supplementary material, which is available to authorized users. * Wenhua Zhang [email protected] * Guang Yang [email protected] 1
Green Catalysis Center, and College of Chemistry, Zhengzhou University, Zhengzhou 450001, Henan, People’s Republic of China
zirconia nanoparticles for photocatalytic degradation of PNP [7]. Ma and Cheng reported a template protection–sacrifice (TPS) method to prepare a composite catalyst of Cu2O@ ZIF-8, which exhibits excellent activity towards the hydrogenation of PNP in the presence of NaBH4 [8]. Xu and coworkers studied the use of acid-activated coal fly ash as PNP-adsorbent with the adsorption capacity being 1.07 mg/g at pH 6.5 [9]. Among these methods, adsorption is considered to be a promising solution to remove PNP in a quick and simple way [10]. Commonly used solid adsorbents are activated carbon, biological materi
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