Comparative Study of CoFe2O4 Nanoparticles and CoFe2O4-Chitosan Composite for Congo Red and Methyl Orange Removal by Adsorption.

Claudia Maria Simonescu,Bogdan Butoi,Ana-Maria Banici,Ioana Alexandra Ionescu,Alina Tătăruş,Nicolae Stănică,Daniela Cristina Culiţă

doi:10.3390/nano11030711

Abstract

(1) Background: A comparative research study to remove Congo Red (CR) and Methyl Orange (MO) from single and binary solutions by adsorption onto cobalt ferrite (CoFe2O4) and cobalt ferrite–chitosan composite (CoFe2O4-Chit) prepared by a simple coprecipitation method has been performed. (2) Methods: Structural, textural, morphology, and magnetic properties of the obtained magnetic materials were examined by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, N2 adsorption–desorption analysis, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and magnetic measurements. The optimal operating conditions of the CR and MO removal processes were established in batch experiments. The mathematical models used to describe the processes at equilibrium were Freundlich and Langmuir adsorption isotherms. (3) Results: Cobalt ferrite–chitosan composite has a lower specific surface area (SBET) and consequently a lower adsorption capacity than cobalt ferrite. CoFe2O4 and CoFe2O4–Chit particles exhibited a superparamagnetic behavior which enabled their efficient magnetic separation after the adsorption process. The research indicates that CR and MO adsorption onto prepared magnetic materials takes place as monolayer onto a homogeneous surface. According to Langmuir isotherm model that best fits the experimental data, the maximum CR/MO adsorption capacity is 162.68/94.46 mg/g for CoFe2O4 and 15.60/66.18 mg/g for CoFe2O4–Chit in single solutions. The results of the kinetics study revealed that in single-component solutions, both pseudo-first-order and pseudo-second-order kinetics models represent well the adsorption process of CR/MO on both magnetic adsorbents. In binary solutions, adsorption of CR/MO on CoFe2O4 better follows the pseudo-second-order kinetics model, while the kinetic of CR/MO adsorption on CoFe2O4–Chit is similar to that of the dyes in single-component solutions. Acetone and ethanol were successfully used as desorbing agents. (4) Conclusions: Our study revealed that CoFe2O4 and CoFe2O4–Chit particles are good candidates for dye-contaminated wastewater remediation.

Highlights

Cobalt ferrite and cobalt ferrite–chitosan composite were synthesized by a simple coprecipitation method to be used as effective adsorbents for removal of Congo Red and Methyl Orange dyes from single and binary aqueous solutions
The as-obtained magnetic materials prepared were characterized by Fourier-transform infrared (FTIR) spectroscopy, specific surface area and porosity analysis, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) analysis, X-Ray diffraction, and magnetic measurements
The optimal parameters of the Congo Red (CR)/Methyl Orange (MO) retention process on the prepared cobalt ferrite/cobalt ferrite–chitosan composite were determined from batch experiments at room temperature in single and binary dye solutions

Summary

Introduction

Improper disposal of pollutants such as heavy metal ions, dyes, pharmaceutical wastes, pesticides, organic compounds into aquatic environments constitutes one of the Nanomaterials 2021, 11, 711. Dyes are basic chemical compounds that are utilized in many industrial practices such as textile, paper, leather, plastics and rubber, food, pharmaceutical, and cosmetics industrial practices. When effluents with dyes are discharged into various water sources, the turbidity of the water increases as the effluents will produce a visible layer on the surface of the water sources due to the low density (0.8 kg/m3 ) compared to the density of water (1 kg/m3 ) [3]. The sunlight necessary for the processes of photosynthesis and respiration of aquatic organisms will not penetrate through the dye layer determining the death or aquatic organisms. The decrease in soil productivity can be registered in the situation when effluents containing dyes will be discharged in soils by blocking their pores [3]

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Conclusion