Fabrication of NiFe₂O₄ magnetic nanoparticles loaded on activated carbon as novel nanoadsorbent for Direct Red 31 and Direct Blue 78 adsorption

ABSTRACT

In this research, magnetic nickel ferrite NiFe₂O₄/hazelnut-shell-based activated carbon (NiFe₂O₄/AC) was used to eliminate anionic dyes (Direct Red 31(DR31) and Direct Blue 78 (DB78)) from aqueous solution. The morphological, structural, particle size and surface charge properties of as-prepared nanoadsorbent were characterized. TEM (Transmission electron microscopy) images revealed that the size of NiFe₂O₄ particles in the structure of AC was in the range of 8-12 nm, which is compatible with the results obtained by the analysis of DLS (Dynamic light scattering). The results of the BET (Brunauer–Emmett–Teller) analysis indicated that the surface area, the pore volume and average pore diameters of the NiFe₂O₄ were 288 m²/g, 0.3338 cm³/g and 5.05nm, respectively. The as-prepared nanocomposite showed excellent adsorption capacity for DR31 and DB78 dyes with the highest adsorption capacity obtained at pH=2.0 and rapid dye adsorption equilibrium attained after 20 and 25 min for DR31 and DB78, respectively. The equilibrium study showed the maximum adsorption capacity (q_max) of 299.67 mg/g and 209.13 mg/g for DR31 and DB78, respectively. In addition, thermodynamic study revealed the endothermic and spontaneous nature of adsorption process. The adsorption of DR31 and DB78 onto the NiFe₂O₄/AC is a physisorption process, during which electrostatic adsorption was the main driving force.

KEYWORDS:

• NiFe₂O₄ nanoparticles
• magnetic separation
• DR31
• DB78
• adsorption

Disclosure statement

No potential conflict of interest was reported by the authors.