Anionic azo dyes removal from water using amine-functionalized cobalt-iron oxide nanoparticles: a comparative...

Area of Science:

• Materials Science
• Environmental Chemistry
• Nanotechnology

Background:

• Textile industry wastewater contains negatively charged azoic dyes, posing environmental challenges.
• Magnetic nanoparticles offer potential for efficient pollutant removal due to their magnetic separability and high surface area.
• Functionalization of nanoparticles can enhance their adsorption properties for specific pollutants.

Purpose of the Study:

• To synthesize and characterize magnetic cobalt-iron oxide nanoparticles (CoFeNPs) functionalized with hydrazine (CoFeNPs1) and dodecylamine (CoFeNPs2).
• To evaluate and compare the efficiency of CoFeNPs1 and CoFeNPs2 in removing six different azoic dyes from aqueous solutions.
• To investigate the influence of various factors, including time, functionalization, nanoparticle size, and dye structure, on dye removal efficiency.

Main Methods:

• Synthesis and characterization of magnetic cobalt-iron oxide nanoparticles using FT-IR, AFM, SEM-EDS, ζ-potential, and thermal analysis.
• Batch adsorption experiments to assess dye removal efficiency under varying conditions (time, pH, adsorbent dose, temperature).
• Kinetic, isotherm, and thermodynamic studies to understand the adsorption mechanism and reusability of the adsorbents.

Main Results:

• CoFeNPs2 demonstrated significantly higher dye removal (68.0-98.9%) compared to CoFeNPs1 (44.5-82.1%).
• Adsorption capacity (q_e) for CoFeNPs2 ranged from 6.6-23.5 mg g⁻¹, while CoFeNPs1 showed 5.4-13.5 mg g⁻¹.
• Dye removal by CoFeNPs2 was favored by larger dye size, complex structure, hydrophobicity, and more phenyl SO₃⁻ groups; pseudo-second order kinetics and Langmuir isotherm best described the adsorption process.

Conclusions:

• Amine-functionalized CoFeNPs, particularly CoFeNPs2, are effective and reusable adsorbents for removing azoic dyes from wastewater.
• The adsorption process is spontaneous, exothermic, and influenced by dye structural characteristics and nanoparticle functionalization.
• CoFeNPs offer a cost-effective solution for rapid and selective dye removal from textile effluents.