Research paper
Electrocatalysis degradation of tetracycline in a three-dimensional aeration electrocatalysis reactor (3D-AER) with a flotation-tailings particle electrode (FPE): Physicochemical properties, influencing factors and the degradation mechanism

https://doi.org/10.1016/j.jhazmat.2020.124361Get rights and content

Highlights

  • FPE were prepared as novel particle electrodes mainly using the flotation tailings.

  • TC could be effectively adsorbed by FPE.

  • Key factors on TC of 3D-AER degradation were evaluated.

  • Degradation mechanism under 3D-AER with FPE was proposed.

  • Degradation pathways were speculated with several typical intermediates identified.

Abstract

Novel particle electrodes, i.e. flotation tailings particle electrode (FPE), were prepared using flotation tailings, garden soil, and soluble starch with a mass ratio of 16:3:1, and then used in tetracycline wastewater treatment. The physicochemical properties of FPE were systematically characterized using SEM, XRD, FT-IR and XRF. Tetracycline adsorption and its adsorption mechanism onto FPE was explored for the first time. Parameters affecting FPE’s degradation efficiency and energy consumption such as current density, electrolysis time, initial concentration, initial pH and aeration rate were examined. The electrocatalytic degradation of tetracycline shows that the degradation of tetracycline meets the pseudo-first-order kinetics. Moreover, the numbers of •OH produced on the surfaces of the cathode, anode and particle electrode were compared. Results showed that the adsorption-saturated FPE can be regenerated by electrochemical action to induce further absorption and form in-situ electrocatalysis. In order to find out the transformation products in water and degradation pathways of Tetracycline, UHPLC method was used to obtain the degradation pathways for Tetracycline. So, this work could provide a fabrication of high-efficiency and low-cost electrocatalytic for removal of pharmaceuticals pollutants from waste water as well as deeper insight into electrocatalytic mechanism, transformation products, and degradation pathways of Tetracycline in water.

Introduction

In recent years, antibiotics have been frequently detected in sewage treatment plants (Gurung et al., 2019, Peng et al., 2006), rivers (Zhang et al., 2020) and drinking water (Charuaud et al., 2019). Extrapolating from the latest findings, ascribed antibiotics have a lingering presence in the environment to they do not degrade easily. Antibiotics present in the water environment can lead to the rise of antibiotics resistance genes (ARGs) in humans and animals. Long-term abuse of antibiotics is likely to induce the excretion of ARGs, in animals, causing potential genetic pollution to the surrounding environment (Kairigo et al., 2020). The problem of antibiotic resistance has become one of the global public health safety problems (Abubakar et al., 2020). Particularly widespread use on humans and animals is made of tetracycline (TC), an antibiotic utilized in the treatment of various microbial diseases such as malaria, cholera, bubonic plague, acne, skin and respiratory tract infections (Mosaleheh and Sarvi, 2020, Debnath et al., 2020, Sun et al., 2019). Moreover, TC is unable to completely metabolize in vivo, and therefore large fractions are released into the environment through urine and feces. Therefore, it is urgently important to find an effective remediation process to remove TCs from water.

The existing physical methods, such as coagulation and adsorption, only shift the boundary phase but cannot reduce resistance, while also making the subsequent treatment process more difficult. The biological method leads to the horizontal transmission of resistance genes because of their large biomass, which increases the risk of resistance gene survival. At the same time, TC can reduce the efficiency of the biochemical reaction, have a significantly harmful impact on microorganisms and even lead to the collapse of the bioreactor. Furthermore, although a certain quantity of TC is degraded by microorganisms, the relative abundance of antibiotic resistance genes (ARGs) will also increase (Cheng et al., 2016, Sui et al., 2016). This is due to the proliferation of its host bacteria in the wastewater treatment process or the horizontal transfer of ARGs to other species (Cheng et al., 2016, Subirats et al., 2018). The advanced oxidation process (AOP) is a kind of oxidation reaction with a hydroxyl radical (·OH) as the main active species which has a good mineralization effect on new pollutants such as antibiotics and hormones in the environment. It has a very good degradation effect on TC and has a very high degree of mineralization, thus reducing resistance in the environment. Thanks to this feature, it has attracted the attention of scholars (Wang and Zhuan, 2020).

Electrochemical technology as a type of AOP has made great progress in the treatment of wastewater containing organic pollutants. In fact, electrochemical oxidation provides another solution to many environmental problems in the processing industry, because electrochemical processes are clean, cheap and easy to control, hence their widespread application in environmental pollution control (Ozturk and Yilmaz, 2019, Martínez-Huitle and Panizza, 2018). Furthermore, some researchers developed particle electrodes to be placed between the cathode and anode, and constructed a three-dimensional electrocatalysis system to reduce the mass transfer distance, improve the current efficiency and increase the production of free radicals in the electrocatalysis system (Wu et al., 2019, Zhang et al., 2013). When aeration was added in the electrochemical oxidation reaction, this yielded significant speed advantages (Sun et al., 2017).

According to statistics, 125 tons of tailings are produced for every ton of copper produced (Santander and Valderrama, 2019). Due to the decline in ore grade and process complexity, the production of tailings is increasing year by year. The accumulation of these tailings has brought serious pollution and harm to production and human life, such as environmental and land occupancy hazards as well as the hidden dangers of stacking land. There are also rich and varied chemical elements in flotation tailings, which are of great value in utilization. Therefore, we believe that flotation tailings can give rise to durable electrocatalytic particle electrodes with good mechanical strength, high thermal stability, corrosion resistance and well-developed pore structure under the appropriate proportion and with adequate firing process. In this article, based on the awareness of mineral resource and environmental protection, the particle electrode placed between cathode and anode is made of flotation tailings as well as cheap and simple binders and pore-forming agents, thus greatly reducing its manufacturing cost.

In this study, the main procedures were as follows: I) novel particle electrodes-Flotation-tailings particle electrode (FPE) was prepared using the flotation tailings, garden soil, and soluble starch; II) the physicochemical properties of FPE were characterized by SEM, XRD,FT-IR and XRF methods; III) the adsorption mechanism of tetracycline in solution by FPE was investigated; IV) a three-dimensional aeration electrocatalysis reactor (3D-AER) was constructed and the factors affecting the degradation of tetracycline (TC) and its current efficiency (CE) and current energy consumption (EC) were studied; VI) the kinetics of tetracycline degradation by 3D-AER were analyzed; VII) the action mechanism of·OH in the reaction system was studied by using free radical scavenger tert butyl alcohol (TBA); VIII) the transformation products in water and degradation pathways of Tetracycline was obtained by Ultimate 3000 UHPLC - Q Exactive method.

Section snippets

Chemicals

Tetracycline (TC), NaCl, tert butyl alcohol (TBA) and soluble starch were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., China. The garden soil comes from the green belt of the University of Jinan. The chemical reagents were used as received. The plexiglass shell was customized in Jinan Jinhui Plexiglass Production Company. The ruthenium iridium-plated titanium mesh was ordered from Jinan Zhuangmeng Co., Ltd.

Preparation of FPE

The primary materials of the flotation-tailings particle electrode

Structural characteristics of FPE

The surface morphologies of FPE were analyzed by SEM technologies. As shown in Fig. 2(a) and (c), the surface and interior of FPE are rough and porous, indicating that FPE possesses numerous, uniform and small pore networks, which can provide extensive active sites and abundant electronic transport pathways, which effectively increases the contact area between sewage and FPE, thus improving the removal rate of TC. Notably, the FPE fault surface (Fig. 2(d)) displays a typical schistose structure

Conclusion

In this study, we carried out several sets of experiments to test the validity of FPE for 3D-AER:

  • I)

    Preparation of a flotation-tailings particle electrode (FPE): stoving → crushing → proportioning (flotation tailings, garden soil, and soluble starch with a mass ratio of 16:3:1) → blending → ball milling → calcining (1150 ℃) → cooling. Finally FPE was successfully manufactured thanks to these steps. Characterization of FPE: by SEM, XRD, FT-IR and XRF methods, we found that PFE has a high proportion

CRediT authorship contribution statement

Shumin Yang:Conceptualization, Ideas, Methodology, Software, Data curation, Writing - review & editing. Yan Feng: Conceptualization, Ideas, Methodology, Data curation, Supervision, Funding acquisition. Dong Gao: Formal analysis, Data curation. Ning Suo: Investigation, Data curation. Xinwei Wang: Resources, Data curation. Yanzhen Yu: Formal analysis, Data curation. Shoubin Zhang: Resources, Methodology, Data curation, Investigation.

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.

Acknowledgements

This work was funded by a Project of Shandong Province Higher Educational Youth Innovation Science and Technology Program (2020KJG003), the Key Research and Development Plan of Shandong Province (2019GSF109005 and 2017GSF217011), the Natural Science Foundation of Shandong Provincial, China (ZR2017MEE048), the Natural Science Foundation of China (NSFC51678276 and NSFC51608228), the Funding Program of 20 Policies for Universities in Jinan (2018GXRC020). This paper was also supported by the PhD

References (63)

  • Y. Huang et al.

    Catalytic degradation of ciprofloxacin by magnetic CuS/Fe2O3/Mn2O3 nanocomposite activated peroxymonosulfate: Influence factors, degradation pathways and reaction mechanism

    Chem. Eng. J.

    (2020)
  • X. Huang et al.

    Enhanced heterogeneous photo-Fenton catalytic degradation of tetracycline over yCeO2/Fh composites: performance, degradation pathways, Fe2+ regeneration and mechanism

    Chem. Eng. J.

    (2020)
  • A.W.M. Ip et al.

    A comparative study on the kinetics and mechanisms of removal of Reactive Black 5 by adsorption onto activated carbons and bone char

    Chem. Eng. J.

    (2010)
  • P. Kairigo et al.

    Occurrence of antibiotics and risk of antibiotic resistance evolution in selected Kenyan wastewaters, surface waters and sediments

    Sci. Total Environ.

    (2020)
  • W. Konicki et al.

    Adsorption of cationic dyes onto Fe@graphite core–shell magnetic nanocomposite: equilibrium, kinetics and thermodynamics

    Chem. Eng. Res. Des.

    (2018)
  • A. Kumar et al.

    Sodium bentonite and kaolin clays: comparative study on their FT-IR, XRF, and XRD, Mater

    Today Proc.

    (2020)
  • E.C. Lima et al.

    A critical review of the estimation of the thermodynamic parameters on adsorption equilibria. Wrong use of equilibrium constant in the Van’t Hoof equation for calculation of thermodynamic parameters of adsorption

    J. Mol. Liq.

    (2019)
  • Z. Lin et al.

    Perchlorate formation during the electro-peroxone treatment of chloride-containing water: effects of operational parameters and control strategies

    Water Res.

    (2016)
  • Y. Liu et al.

    Degradation kinetics and mechanism of oxytetracycline by hydroxyl radical-based advanced oxidation processes

    Chem. Eng. J.

    (2016)
  • H. Liu et al.

    Insights into degradation pathways and toxicity changes during electro-catalytic degradation of tetracycline hydrochloride

    Environ. Pollut.

    (2020)
  • B. Liu et al.

    Regeneration of carbon nanotube saturated with tetracycline by microwave-ultraviolet system: performance and degradation pathway

    Chem. Eng. J.

    (2020)
  • P. Li et al.

    Comparison of two-stage acid-alkali and alkali-acid pretreatments on enzymatic saccharification ability of the sweet sorghum fiber and their physicochemical characterizations

    Bioresour. Technol.

    (2016)
  • X. Li et al.

    Efficient degradation of tetracycline by CoFeLa-layered double hydroxides catalyzed peroxymonosulfate: synergistic effect of radical and nonradical pathways

    J. Hazard. Mater.

    (2020)
  • J. Li et al.

    Electrochemical pretreatment of coal gasification wastewater with Bi-doped PbO2 electrode: preparation of anode, efficiency and mechanism

    Chemosphere

    (2020)
  • Z. Li et al.

    Highly efficient removal of chlorotetracycline from aqueous solution using graphene oxide/TiO 2 composite: properties and mechanism

    Appl. Surf. Sci.

    (2017)
  • H. Li et al.

    Enhanced activation of molecular oxygen and degradation of tetracycline over Cu-S4 atomic clusters

    Appl. Catal. B Environ.

    (2020)
  • Z. Li et al.

    Electrophoretic deposition of graphene-TiO2 hierarchical spheres onto Ti thread for flexible fiber-shaped dye-sensitized solar cells

    Mater. Des.

    (2016)
  • T. Luo et al.

    Efficient degradation of tetracycline by heterogeneous electro-Fenton process using Cu-doped Fe@Fe2O3: Mechanism and degradation pathway

    Chem. Eng. J.

    (2020)
  • H.T. Madsen et al.

    Study of degradation intermediates formed during electrochemical oxidation of pesticide residue 2,6-dichlorobenzamide (BAM) at boron doped diamond (BDD) and platinum-iridium anodes

    Chemosphere

    (2014)
  • C.A. Martínez-Huitle et al.

    Electrochemical oxidation of organic pollutants for wastewater treatment

    Curr. Opin. Electrochem.

    (2018)
  • Q. Ma et al.

    Synthesis of magnetic CuO/MnFe2O4 nanocompisite and its high activity for degradation of levofloxacin by activation of persulfate

    Chem. Eng. J.

    (2019)
  • Cited by (75)

    View all citing articles on Scopus
    View full text