Oxidative degradation of Rhodamine B by Ag@CuO nanocomposite activated persulfate

doi:10.1016/j.synthmet.2020.116479

Synthetic Metals

Volume 267, September 2020, 116479

https://doi.org/10.1016/j.synthmet.2020.116479 Get rights and content

Highlights

•
The Ag@CuO nanocomposite was synthesized by a simple chemical reaction.
•
The Ag@CuO nanocomposite was used as a persulfate activator in the oxidative degradation of RHB.
•
The Ag@CuO nanocomposite has excellent catalytic performance in persulfate activation for RHB oxidation.
•
The Ag@CuO nanocomposite has an excellent long-term stability in RHB oxidation.

Abstract

In this study, the Ag@CuO nanocomposite was prepared by a simple chemical reaction, and successfully used as a persulfate activator in the oxidative degradation of Rhodamine B (RHB). The micromorphology, crystal structure, elemental composition and content, and chemical state of Ag@CuO nanocomposite were characterized by high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray energy spectrum analysis (EDS), inductively coupled plasma-atomic emission spectrometry (ICP-AES), and X-ray photoelectron spectroscopy (XPS), respectively. The activator possesses a minor particle agglomeration. The degradation efficiency and degradation kinetics of RHB were investigated by different catalysts activated persulfate and at different temperatures. The results revealed that the Ag@CuO nanocomposite has better catalytic activity for the activation of persulfate potassium to degrade RHB than the contrastive activators. The oxidative degradation of RHB is a pseudo-first order reaction, and the higher temperature is benefit for the RHB degradation. The Ag@CuO nanocomposite presented a long-term stability through the cycle experiment in the degradation of RHB.

Graphical abstract

The synthetic Ag@CuO nanocomposite has excellent catalytic performance in the activation of persulfate potassium for the oxidative degradation of RHB.

Introduction

With the rapid development of the economy, the demand for dyes used in the clothing and coating industry as well as in life, has gradually increased year by year, which may result in a series of unfavorable environment problems during the process of production and use [1,2]. If handled improperly, these problems could pose a serious threat to human health and the ecological environment. The search for solving these problems caused by excessive use of dyes is quite crucial. The traditional methods including sedimentation-filtration, sorptive extraction [3,4], and more advanced biological process such as activated sludge reactors and trickling filters [5,6] have been utilized. In addition, photocatalysis is also a popular process for dye degradation [7,8]. However, these methods are not capable of causing degradation of organic dyes with stable molecular structure and high toxicity, which lead to the residua for most of the dye molecules in the soil and water [9,10]. Therefore, the development of more effective techniques for degrading dye molecules is a pressing concern in the consideration of solving the various environment problems.

In recent years, advanced oxidation process (AOPs) has become a effective and promising technology for the treatment of organic matters in soil and groundwater [[11], [12], [13]], which is characterized by the addition of chemical oxidants, such as hydrogen peroxide, permanganate, ozone and persulfate to the organic matters or waste pollutants [14]. Compared with other oxidants, persulfate has attracted remarkable attention although it was rarely reported in the literature [[15], [16], [17]]. This can be attributed mainly to its good solubility and high oxidation potential (E° = 2.01 V). In addition, persulfate is relatively stable and can be easily injected into the target pollutants when in use. Persulfate can be decomposed into sulfate radical (SO₄⁻) with strong oxidization in a broad pH range, whose oxidation potential (E° =2.6 eV) is considerably larger than that of persulfate. In the process of degrading organic matter, sulfate free radicals sometimes can react with many pollutants freely, producing other active oxidizing substances, such as hydroxyl free radicals (OH), peroxymonosulphate (HSO₅⁻) and hydrogen peroxide (H₂O₂), all of which play important roles in the oxidative degradation of organic pollutants in soil and water. But the process for persulfate into sulfate free radicals also need to be activated, which can be realized by heating [18], ultraviolet [19,20], alkali [21], transition metals [22], soil minerals [23], radiation decomposition [24], metal ions and so on [25,26].

Among the aboved-mentioned activation ways, metal ions have received special attention in recently years, largely due to its stable existence in a homogeneous system, and easier application in practice without the addition of external energy. However, this activation way needs to be done in an environment of strong acid or alkali, which could pose a great threat to the environment. Moreover, these metal ions are difficult to retrieve after activation, which usually left in soil and water for a long time, causing the secondary pollution to the environment. Consequently, more and more researches have adopted the heterogeneous catalyst such as zero-valent iron (nZVI) [27] and iron oxide (Fe₃O₄) [28] to replace the metal ions for activating PS, which is attribute to their convenient separation and environmental friendliness [29,30]. However, nZVI is easy to be oxidized in the air owing to its high surface energy [31] and Fe₃O₄ is confronted with poor catalytic performance for PS activation because this magnetic material can easy to aggregate. Consequently, it is quite crucial to find a stable metal-based heterogeneous catalysts that can further improving the catalytic performance.

Copper oxide structures have been widely used to active PS for wastewater purification because of their satisfactory catalytic performance [32,33], But the significant leaching of Cu²⁺ ions from CuO into the aqueous phase limits the repeated use of CuO catalyst. In addition, bare CuO has high running cost because it is not easy to be separated from suspension system. Research shows that the addition of metallic silver (Ag) could effectively activate PS [16,34]. Li et al. [16] reported that a group of the silver-doped bismuth ferrite catalysts with variable Ag content (Ag_x-BiFeO₃), and applied as heterogeneous catalyst in PS activation for tetracycline (TC) degradation. In particular, Ag_0.4-BiFeO₃ catalyst had the best catalytic performance, 91 % of TC was removed after 60 min treatment. It can be speculated that that the doping Ag into the CuO nanoparticles will promote the activation of PS. This means that the Ag doped CuO material is a composite with high catalytic performance.

Herein, in this paper, the inexpensive and readily available basic copper carbonate was used as the starting material to react with silver nitrate through ion exchange reaction for 24 h. The intermediate was subsequently calcined at 300℃ to obtain the silver coated copper oxide nanocomposite (Ag@CuO). Finally, the Ag@CuO nanocomposite was utilized to activate potassium persulfate for the oxidative degradation of RHB. The chemical structure of RHB was shown in Fig. 1. The micromorphology, crystal structure, elemental composition and content, and chemical state of Ag@CuO nanocomposite were characterized by high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray energy spectrum analysis (EDS), inductively coupled plasma-atomic emission spectrometry (ICP-AES), and X-ray photoelectron spectroscopy (XPS), respectively. The degradation efficiency and apparent rate constants (K_obs) of RHB were discussed by different persulfate activators and at various temperatures. The results implied that the formation of dispersed AgNPs coat on the surface of CuO, and Ag@CuO nanocomposite was to be a highly active nanocatalyst for the activation of persulfate.

Section snippets

Reagents and instruments

Basic copper carbonate, potassium persulfate, Rhodamine B were of analytical grade and purchased from the Sinopharm Chemical Reagent Company (Shanghai, China) without further puriﬁcation. Ultrapure water (18.2 MΩ cm) obtained from a Millipore pure water instrument was used in all experiments. The absorbance of RHB aqueous solution was measured by ultraviolet spectrophotometer (UV3600, Shimadzu, Japan). The crystal structure and micromorphology of Ag@CuO nanocomposite were characterized by an

Characterization of Ag@CuO nanocomposite

The composition and crystallinity of Ag@CuO nanocomposite was studied by XRD. As shown by the curves in Fig. 2a, the prepared Ag@CuO catalyst shows the diffraction peaks of 2θ at 32.4, 35.5, 38.7, 48.9, 53.3, 58.3, 61.6, 66.4, 68.1, 72.4, 75.0 and 82.8° (JCPDS: 42-1411), which could be assigned to that of copper oxide [36,37]. Evidently, the diffraction peaks of silver can’t be easily identified in XRD pattern, mainly because the amount of silver coated on copper oxide is too low (consistent

Conclusions

In conclusion, the Ag@CuO nanocomposite with small particle size has been synthesized by a simple chemical reaction. The Ag@CuO nanocomposite has excellent catalytic performance in the activation of persulfate potassium for the oxidative degradation of RHB. Dynamics study demonstrated that the degradation of RHB is a pseudo-first order reaction with a good linear relationship. The K_obs of RHB increased with the increasing temperature. The Ag@CuO nanocomposite has an excellent long-term

Author statement

We appreciate support from the Natural Science Foundation of Anhui Education Department (KJ2018A0525), and the Excellent Talents Program of of Anhui Province (gxyq2019062).

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

References (44)

G. Shen et al.
Chin. J. Catal.
(2018)
L.R. Luo et al.
J. Alloys Compd.
(2013)
C.I. Pearce et al.
Dyes Pigments
(2003)
N. Supaka et al.
Chem. Eng. J.
(2004)
J. Han et al.
Appl. Catal. A
(2016)
M. Doğan et al.
Dyes Pigments
(2007)
T. Zhang et al.
Sep. Purif. Technol.
(2020)
M. Ouyang et al.
J. Colloid Interface Sci.
(2020)
S. Li et al.
Environ. Int.
(2020)
J. Saien et al.
Chem. Eng. J.
(2011)

Y. Ji et al.

Water Res.

(2018)

X.R. Xu et al.

Sep. Purif. Technol.

(2010)

C.S. Liu et al.

Sci. Total Environ.

(2012)

A. Jonidi Jafari et al.

J. Ind. Eng. Chem.

(2017)

J. Yan et al.

J. Hazard. Mater.

(2011)

C. Qi et al.

Chem. Eng. J.

(2014)

X.D. Du et al.

Chem. Eng. J.

(2017)

Y. Li et al.

J. Mol. Catal. A-Chem.

(2016)

Q. Ma et al.

Chem. Eng. J.

(2019)

L. Bai et al.

J. Taiwan Inst. Chem. E.

(2019)

S.O. Sanni et al.

J. Mol. Liq.

(2020)

J. Lyu et al.

Chem. Eng. J.

(2020)

Cited by (18)

Activation of persulfate using copper oxide nanoparticles for the degradation of Rhodamine B containing effluents: Degradation efficiency and ecotoxicological studies
2023, Chemical Engineering Journal
Citation Excerpt :
There are limited reports in the literature on the activation of persulfate using the heterogeneous catalysis with copper-based materials. For instance, a recent study indicated that an Ag-doped copper oxide/PS system (1 g/L) resulted in the complete removal of RhB (50 mg/L) in 30 min of reaction [50]. The high efficiency of the CuO prepared in this study can be related to high degree of purity of the materials as a result of the ultrasonic irradiation-based method used in this study, responsible for their low particle size and high specific surface area.
The development and implementation of advanced oxidation processes (AOP) are intended to assist in the treatment of effluents produced during anthropogenic activities, reducing the release of chemicals to the environment and consequently their potential toxicity to the environment. The present work is intended to assess the chemical and ecotoxicological efficiency of an AOP that uses copper oxide nanoparticles (CuO-NP) and persulfate (PS, as an oxidation agent) for the removal of Rhodamine B (RhB) from an aqueous solution. For this, CuO-NPs were prepared and used as a sole catalyst or combined with thermal treatment to activate PS for the degradation of RhB (in distilled water, DI, and in ASTM medium). Kinetic and mechanistic studies were employed to understand the performance of the system. The lethal ecotoxicity of the untreated and treated RhB solution was characterized using rotifer species Brachionus calyciflorus. Complete removal of RhB was achieved at [RhB]₀ = 50 mg/L, [PS]₀ = 1 mM, CuO = 0.5 g/L under pH = 7.5 at 45 °C for DI and ASTM. Brachionus calyciflorus mortality pointed to a very high ecotoxicity of the effluent before and after the AOP treatment; the former was less toxic than the latter: LC_50,24h = 44.3% and 8.24%, respectively. Mortality observed in the treated effluent was most probably due to the presence of reaction products (e.g., activated PS) rather than RhB, since CuO/PS system was able to remove >90% of RhB. The obtained results demonstrated that although the proposed method is applicable to deal with high concentrations of recalcitrant organic compounds, the treated effluents can cause high ecotoxicity when released into the environment.
Recyclable CuO@CSs as highly efficient peroxymonosulfate activator for Rhodamine B degradation
2023, Journal of Physics and Chemistry of Solids
A high stable and efficient catalyst of CuO@CSs (carbon silicion sphere@CuO) was prepared through in-situ growth methods. CuO@CSs as a heterojunction was conducive to activate PMS efficiently. 15 ppm of RhB was completely removed after 2 min with 0.5 mM peroxymonosulfate (PMS) under UV–visible light irradiation. The reusability of catalyst was evaluated through recycling tests, and the RhB degradation efficiency ranged from 99.96% to 99.37% after five cycles. ¹O₂ and O₂^•−were detected by trapping experiments and electron paramagnetic resonance (EPR) in the photocatalytic degradation, which have worked together in the removal of RhB. Furthermore, the CuO@CSs/PMS was applied to treat natural water containing RhB, which was completely decomposed within 8 min. The possible photocatalytic degradation mechanism for the RhB was investigated. The degradation pathway of RhB was deduced through LC-MS results, it was concluded that CuO@CSs was a recyclable catalyst to activate PMS and remove organic pollution.
Promoting the performance of electrooxidation-PMS system for degradation of tetracycline by introduction of MnFe<inf>2</inf>O<inf>4</inf>/CNT as a third-electrode
2022, Separation and Purification Technology
Citation Excerpt :
As a typical AOP technology, electrochemical oxidation (EC) has the characteristics of simple operation, energy saving, high efficiency and being environment-friendly in the aspect of treating organic wastewater [9–12]. In recent years, AOP based on sulfate radical (SO4−•) has been of considerable interest to researchers due to its long half-life of SO4−•, wide range of pH value, strong selectivity to pollutants, and difficulty in being affected by inorganic ions in water [13–15]. Permonosulfate (PMS) is a strong oxidant that can provide sulfate radical, but has a low reaction rate with organic matter [16].
In this work, MnFe₂O₄/CNT was introduced into electrochemical oxidation (EC)-peroxymonosulfate (PMS) system to be served as a third electrode. In which, 20 wt% MnFe₂O₄/CNT due to its excellent physical characterization was proven to promote the catalytic degradation performance of tetracycline (TC). The optimal conditions for EC-20 wt% MnFe₂O₄/CNT-PMS on TC removal efficiency was investigated by dosage of catalyst, dosage of oxidant, current density and initial pH of TC. When 20 wt% MnFe₂O₄/CNT was injected at 0.1 g·L⁻¹, PMS was injected at 6 m M, current density was 10 mA·cm⁻², initial pH was 5.9, and reaction time was 120 min, TC removal rate reached 87.7%. The effect of humic acid (HA) on TC degradation was investigated by simulating real water bodies. The results showed that EC-20 wt% MnFe₂O₄/CNT-PMS system was less affected by water background. Judging by capturing free radicals’ experiments, it proved that this novel system facilitates to make much more •OH and SO₄⁻• as active species in degradation of TC. The degradation mechanism of TC in the EC-20 wt% MnFe₂O₄/CNT-PMS system was estimated by XPS analysis of catalysts before and after the reaction. This research provides a new perspective for electrochemical oxidation by introducing nanomaterials as microelectrodes.
Flower-like hierarchical Sn<inf>3</inf>O<inf>4</inf>/montmorillonite nanostructure for the enhanced microwave-induced degradation of rhodamine B
2022, Advanced Powder Technology
Citation Excerpt :
However, from the DE values, the degradation efficiencies are about 98–99 %, that are obtained at short time; 20 min. It is interesting to note that the DE values obtained in this study are quite higher than those of several methods applied for RhB degradation, either by photocatalytic oxidation or chemical oxidation processes, as listed in Table 4.[33 28 34 35 36 10 37 37 33 28 34 35 36 10 37]. For example, a degradation efficiency of 30% was achieved by photocatalytic oxidation over Sn3O4 for 140 min and a catalyst dosage of 1 g L-1 [10], and a degradation efficiency of 20% was determined for photocatalytic oxidation using Sn3O4 for 20 min [37].
A flower-like hierarchical nanostructure of Sn₃O₄/montmorillonite is first reported in this work. The nanomaterial was prepared by a one-pot hydrothermal synthesis method using tin chloride as the precursor, and the physicochemical characteristics of the material were examined by instrumental analyses. The prepared nanostructure was evaluated as a catalyst in the microwave-induced removal of rhodamine B (RhB). The influences of Sn content, oxidant, time of irradiation, and initial concentration of RhB were investigated. The results showed homogeneously dispersed Sn₃O₄ in a montmorillonite support with a cubic phase, and crystallite size smaller than to Sn₃O₄ was obtained. XPS investigation revealed the Sn₃O₄ phase, which is consistent with the band gap energy of 2.75 eV from UV-DRS measurements. The homogeneous distribution of the Sn₃O₄ nanoparticles influenced the increasing specific surface area of the nanocomposite compared to montmorillonite. The enhanced physicochemical properties significantly enhanced the catalytic activity in microwave induced RhB oxidation, with the degradation efficiency reaching 99.9% after 20 min of treatment. The kinetics of catalytic oxidation were best fitted to the pseudo-second-order equation and obeyed the Langmuir-Hinshelwood kinetics model. Furthermore, the catalytic oxidation condition optimization using a Box-Behnken Design revealed the contribution of oxidant, pH and catalyst dose as influencing factors for the efficiency.
Insights into enhanced peroxydisulfate activation with S doped Fe@C catalyst for the rapid degradation of organic pollutants
2022, Journal of Colloid and Interface Science
Citation Excerpt :
The doped S element not only accelerate electron transfer rate, but it also plays an important role in promoting the Fe(II)/Fe(III) circulation, leading to the promotion on the generation of SO4-·, non-radical 1O2 and Fe(IV) during the PDS activation. Comparted to other catalysts [17 74,75], the S-Fe@C improved the PDS activation by 2 ∼ 19 times, and the S-Fe@C/PDS system could almost completely degrade various organic pollutants in 5 min. This work will provide some theoretical and practical guides for the catalyst design and application of PDS activation process.
In this study, the S modified iron-based catalyst (S-Fe@C) for activating peroxydisulfate (PDS) was fabricated by heating the S-MIL-101 (Fe) precursor at 800 °C. The resulted S-Fe@C composite mainly consisted of carbon, Fe⁰, FeS, FeS₂, and Fe₃O₄, and showed strong magnetism. Compared with Fe@C obtained from MIL-101 (Fe), the S-Fe@C exhibited much higher performance (1.5 times larger) on PDS activation and the S-Fe@C/PDS could rapidly degrade various organic pollutants in 5 min under the attack of the species of SO₄^-·, ¹O₂, electro-transfer and Fe(IV). The S element in enhancing the PDS activation mainly involved two mechanisms. Firstly, the doped S could speed up the electron transfer efficiency, resulting in a promotion on PDS decomposition; secondly, the S^2- S₂^2- or S⁰ could achieve the circulation of Fe²⁺ and Fe³⁺, leading to the formation of non-radicals Fe(IV) and ¹O₂.
Enhanced peroxymonosulfate activation by hierarchical porous Fe<inf>3</inf>O<inf>4</inf>/Co<inf>3</inf>S<inf>4</inf> nanosheets for efficient elimination of rhodamine B: Mechanisms, degradation pathways and toxicological analysis
2022, Journal of Colloid and Interface Science
Fenton-like catalysts have usually superior catalytic activities, however, some drawbacks of ion leaching and difficult-to-recovery limit their applications. In this work, a hierarchical porous Fe₃O₄/Co₃S₄ catalyst was fabricated via a simple phase change reaction to overcome these shortcomings. The introduced iron cooperates with cobalt achieving high-efficiency activation of peroxymonosulfate (PMS) to eliminate Rhodamine B (RhB). The results showed that 0.05 g/L Fe₃O₄/Co₃S₄ and 1 mM PMS could quickly remove 100% of 200 mg/L RhB within 20 min, and the removal rate of RhB remained above 82% after 5 cycles. Moreover, the as-prepared Fe₃O₄/Co₃S₄ possessed a great magnetic separation capacity and good stability of low metal leaching dose. Radical quenching experiments and electron paramagnetic resonance (EPR) techniques proved that sulfate radicals (SO₄^•−) were the dominant reactive oxygen species responding for RhB degradation. X-ray photoelectron spectroscopy (XPS) pointed out that the synergism of sulfur promoted the cycling of Co³⁺/Co²⁺ and Fe³⁺/Fe²⁺, boosting the electron transfer between Fe₃O₄/Co₃S₄ and PMS. Moreover, the degradation pathways of RhB were deduced by combining liquid chromatography-mass spectrometry (LC-MS) analysis and density functional theory (DFT) calculations. The toxicities of RhB and its intermediates were evaluated as well, which provided significant assistance in the exploration of their ecological risks.

View all citing articles on Scopus

View full text

Oxidative degradation of Rhodamine B by Ag@CuO nanocomposite activated persulfate

Highlights

Abstract

Graphical abstract

Introduction

Section snippets

Reagents and instruments

Characterization of Ag@CuO nanocomposite

Conclusions

Author statement

Declaration of Competing Interest

Chin. J. Catal.

J. Alloys Compd.

Dyes Pigments

Chem. Eng. J.

Appl. Catal. A

Dyes Pigments

Sep. Purif. Technol.

J. Colloid Interface Sci.

Environ. Int.

Chem. Eng. J.

Water Res.

Sep. Purif. Technol.

Sci. Total Environ.

J. Ind. Eng. Chem.

J. Hazard. Mater.

Chem. Eng. J.

Chem. Eng. J.

J. Mol. Catal. A-Chem.

Chem. Eng. J.

J. Taiwan Inst. Chem. E.

J. Mol. Liq.

Chem. Eng. J.