Elsevier

Surfaces and Interfaces

Volume 20, September 2020, 100563
Surfaces and Interfaces

Sono-adsorption of organic dyes onto CoFe2O4/Graphene oxide nanocomposite

https://doi.org/10.1016/j.surfin.2020.100563Get rights and content

Abstract

CoFe2O4 loaded graphene oxide (CoF/GO) was synthesized for the sono-adsorption of methylene blue (MB) and methyl violet (MV) dye. The X-ray diffraction pattern of CoF/GO nanocomposite confirmed the inter-layer growth of CoFe2O4 nanoparticles in the GO. The dye adsorption efficiency increased with the increase in pH, time, dye concentration, and adsorbent dosage. The kinetic data were fitted to the pseudo-second-order kinetics (R2 ~1) with theoretical adsorption capacities found closer to the experimental values. The adsorption process was best explained by the Freundlich model due to the heterogeneity of the surface and involvement of physical forces like electrostatic interactions and π-π interactions. The monolayer adsorption capacity was 157 and 122 mg g‒1 for MB and MV, respectively. From thermodynamic parameters, it was concluded that the adsorption process was spontaneous and endothermic. The thermally regenerated CoF/GO showed a performance loss of ~18% after the fourth cycle. From this study, it was conclusive that the magnetic CoF/GO nanocomposite could be used as an economical adsorbent for the removal of organic dyes from wastewater via the sono-adsorption process.

Introduction

In today's industrialized world, the production and application of organic dyes in various industrial activities such as dye manufacturing, tanneries, leather, paper and pulp mills, rubber, and food processing have increased many folds [1]. These industries discharge effluents containing organic dyes into nearby water bodies, which leads to water contamination. These organic dyes are highly carcinogenic that could cause fatal genetic disorders in human beings [2]. Moreover, their presence in water bodies increases the chemical oxygen demand, which threatens the existence of aquatic flora and fauna [3]. Therefore, it is mandatory to pretreat the dye-contaminated wastewater before discharging into the environment.

In the literature, numerous studies have been reported for the removal of organic dyes from wastewater, which has led to the development of different techniques like, adsorption [4], ozonation [5], ultrafiltration [6], oxidation [7], photocatalytic degradation [8,9], adsorption/photocatalytic remediation [10], and ion-exchange [11]. Though the ultrafiltration method could remove charged and neutral dyes, the process is considered unsuitable as the membrane pores are constantly clogged by dye molecules. Methods like oxidation, ozonation, and photocatalytic degradation are known for effective and fast degradation of toxic dyes, but these methods suffer from high operational costs, low pH requirement, oxidant requirement, and/or formation of toxic by-products [12]. Among all these techniques, adsorption is a promising method for the removal of organic dyes due to a moderate cost, high efficiency, and ease of handling. Furthermore, the use of easily recoverable and re-generable adsorbents could lower the overall cost of the process. To remove organic dyes from wastewater, researchers have used adsorption process, where different adsorbents such as biochars [13], metal oxides [14], activated carbon (AC) [15], layered double hydroxides [16] have been utilized. These adsorbents are economical, possess large surface area, and a higher degree of functionalities, which favour the adsorption process. Moreover, incorporation of magnetic nanoparticles like Fe3O4, CoFe2O4, etc. into these adsorbents promotes a faster phase separation (in the presence of external magnetic field) and also provides additional binding sites for the adsorption process [17,18]. Graphene oxide (GO) is known as one of the best adsorbents, which is further supported by a large surface area, high stability, and ease of chemical functionalization [19].

Jiao et al., 2015 studied fast and efficient adsorption of organic dyes over GO/Fe3O4 composite [20]. Banerjee et al., 2017 reported quantitative removal of azo dyes within 6 min using chitosan-GO nanocomposite, where ultrasonication accelerated the adsorption process [21]. The combination of the adsorption and ultrasonication, i.e., sono-adsorption is being explored by researchers in the last few years. The ultrasonication of liquid-solid system accelerates the mass transfer process and makes the process, faster than the conventional adsorption process. Other benefits include degradation of dye molecules by radicals generated in the sonocatalytic process [22] and the creation of newer active sites on the surface of an adsorbent, which enhances the dye removal efficiency.

In this study, we have studied the sono-adsorption of organic dyes onto CoFe2O4 incorporated GO (CoF/GO) nanocomposite. The adsorbent was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Different parameters, i.e., pH, contact time, adsorbent dosage, and initial dye concentration were optimized. The isotherm, kinetics, and thermodynamics of the adsorption process were evaluated. The sono-adsorption mechanism for the adsorption of cationic dyes onto CoF/GO nanocomposite at different pH was proposed. Furthermore, the regeneration and reusability of CoF/GO adsorbent were evaluated to comment on the affordability of the sono-adsorption process.

Section snippets

Chemicals

NaOH solution and GO were procured from TCI Chemicals (India) Pvt. Ltd. Cobalt(II) nitrate hexahydrate (Co(NO3)2•6H2O), Iron(III) nitrate nonahydrate (Fe(NO3)3•9H2O), Methylene blue (MB), and Methyl violet (MV) were purchased from Sigma Aldrich. All the chemicals were of analytical grade and used without further purification.

Synthesis of CoF/GO adsorbent

For the synthesis of CoF/GO adsorbent, precisely Co(NO3)2•6H2O (1.46 g), and Fe(NO3)3•9H2O (4.04 g) were dissolved in 500 mL distilled water and stirred for 10 min at 90

Characterization

The FTIR spectrum of CoF and CoF/GO has been shown in Fig. 1. For CoF, the bands centred at 423 cm‒1 and 578 cm‒1 were assigned to the metal-oxygen vibrations for the metal ions occupied in the octahedral and tetrahedral sites, respectively [8]. For CoF/GO, the broad band centred at 3429 cm‒1 corresponded to the O−H bond vibration, which is complemented by the C−OH band at 1158 cm−1 due to the hydroxyl groups of the GO. Two low-intensity peaks at 2930 cm‒1 and 2850 cm‒1 were due to C−H (sp3)

Conclusion

In this study, we have reported the ultrasonication-assisted adsorption of cationic dyes onto CoF/GO nanocomposite. The XRD analysis confirmed the interlayer growth of spinel CoFe2O4 nanoparticles in GO. The pH-dependent adsorption behaviour showed an increased adsorption capacity with an increase in the pH, which suggested the involvement of π-π interactions between dye molecules and CoF/GO at a low pH and electrostatic attraction between cationic dyes and positively charged CoF/GO surface at

CRediT authorship contribution statement

Anjali Gupta: Conceptualization, Methodology, Software. Herlys Viltres: Visualization, Investigation, Data curation. Nishesh Kumar Gupta: Software, Validation, Writing - review & editing.

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)

  • C. Djilani et al.

    Adsorption of dyes on activated carbon prepared from apricot stones and commercial activated carbon

    J. Taiwan Inst. Chem. Eng.

    (2015)
  • A. Chakraborty et al.

    Facile synthesis of MgAl-layered double hydroxide supported metal organic framework nanocomposite for adsorptive removal of methyl orange dye

    Colloids Interface Sci. Commun.

    (2018)
  • D. Mehta et al.

    Magnetic adsorbents for the treatment of water/wastewater-A review

    J. Water Process. Eng.

    (2015)
  • N.K. Gupta et al.

    2D and 3D carbon-based adsorbents for an efficient removal of HgII ions: a review

    FlatChem

    (2018)
  • P. Banerjee et al.

    Ultrasound assisted mixed azo dye adsorption by chitosan–graphene oxide nanocomposite

    Chem. Eng. Res. Des.

    (2017)
  • Y. Areerob et al.

    Enhanced sonocatalytic degradation of organic dyes from aqueous solutions by novel synthesis of mesoporous Fe3O4-graphene/ZnO@SiO2 nanocomposites

    Ultrason. Sonochem.

    (2018)
  • L. Chen et al.

    Degradation of norfloxacin by CoFe2O4-GO composite coupled with peroxymonosulfate: A comparative study and mechanistic consideration

    Chem. Eng. J.

    (2018)
  • S. Chowdhury et al.

    Recent advances in the use of graphene-family nanoadsorbents for removal of toxic pollutants from wastewater

    Adv. Colloid Interface Sci.

    (2014)
  • R. Subramaniam et al.

    Novel adsorbent from agricultural waste (cashew nut shell) for methylene blue dye removal: optimization by response surface methodology

    Water Resour. Ind.

    (2015)
  • G. Sharma et al.

    Fabrication and characterization of Gum arabic-cl-poly(acrylamide) nanohydrogel for effective adsorption of crystal violet dye

    Carbohydr. Polym.

    (2018)
  • N.K. Gupta et al.

    Biosorption-a green method for the preconcentration of rare earth elements (REEs) from waste solutions: A review

    J. Mol. Liq.

    (2019)
  • N.K. Gupta et al.

    Microscopic, spectroscopic, and experimental approach towards understanding the phosphate adsorption onto Zn–Fe layered double hydroxide

    J. Mol. Liq.

    (2020)
  • Cited by (38)

    View all citing articles on Scopus
    View full text