Efficient removal of Remazol Red dye from aqueous solution using magnetic nickel ferrite nanoparticles synthesized via aqueous reflux

Abstract

Rapid growth of the textile industry, along with the excessive use of water and dyes, has led to significant environmental concerns. This study introduces a straightforward, low-temperature aqueous reflux method for the fabrication of magnetic nickel ferrite (NiFe₂O₄) nanoparticles. The synthesized nanoparticles, characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM), exhibited a cubic spinel structure, an average particle size of 23 ± 2.3 nm (range: 18-29.8 nm), and a magnetization of 56.96 ± 0.9 emu/g, enhancing their surface area and magnetic separability. These NiFe₂O₄ nanoparticles achieved a 96.5 ± 0.4% removal efficiency of Remazol Red dye from aqueous solutions after 90 min, with an adsorption capacity (q_max) of 169.5 ± 0.8 mg/g, as tested across pH 2-12, contact times of 10-120 min, and initial dye concentrations of 20-200 mg/L. Optimal removal occurred at pH 2, with a dye concentration of 20 mg/L and a 1 g/L dose, yielding 99 ± 0.5% efficiency, while adsorption decreased at high pH due to surface charge effects (PZC = 6.7). The results indicated that dye adsorption increased with decreasing pH and higher nickel ferrite dosage. Kinetic studies over 10-120 min followed pseudo-first-order (R² = 0.96), Boyd, and Weber-Morris models, while isotherms across 20-200 mg/L conformed to the Freundlich model (R² = 0.98), reflecting multilayer adsorption. These properties high crystallinity, nanoscale size, and strong magnetic responsiveness enhance the material's surface area, adsorption capacity, and ease of separation, contributing to its efficiency as an adsorbent. Reusability tests confirmed the stability of the nanoparticles and their consistent performance across multiple cycles. These results establish NiFe₂O₄ as an economical, magnetically separable, and ecologically sustainable adsorbent for wastewater treatment purposes.

Keywords: Nickel ferrite; Remazol red dye; Surface adsorption; Wastewater treatment.

Fig. 1

Aqueous reflux synthesis of magnetic nickel ferrite NPs.

Fig. 2

Adsorption of Remazol Red dye on Synthesized Magnetic NiFe₂O₄ NPs.

Fig. 3

UV–Vis absorption spectrum of Remazol Red dye in aqueous solution.

Fig. 4

XRD of synthesized magnetic NiFe₂O₄ NPs.

Fig. 5

FTIR spectrum of synthesized magnetic NiFe₂O₄ NPs.

Fig. 6

(A) SEM, (B) EDX and (C) particle size distribution images of synthesized magnetic NiFe₂O₄ NPs.

Fig. 7

Vibrating sample magnetization of synthesized magnetic NiFe₂O₄ NPs.

Fig. 8

PZC of nickel ferrite NPs.

Fig. 9

Impact of pH on the adsorption efficiency of Remazol Red dye.

Fig. 10

Effect of adsorbent dose on the adsorption efficiency of Remazol Red dye.

Fig. 11

Effect of contact time on the adsorption efficiency of Remazol Red dye.

Fig. 12

Dye concentration effect on the adsorption efficiency of Remazol Red dye.

Fig. 13

Pseudo first order plot for kinetic modeling of Remazol Red adsorbed onto nickel ferrite NPs.

Fig. 14

Pseudo second order plot for kinetic modeling of Remazol Red dye adsorption onto nickel ferrite NPs.

Fig. 15

Weber–Morris for kinetic modeling of Remazol Red dye adsorption onto nickel ferrite NPs.

Fig. 16

B_t versus time for Remazol Red dye adsorption onto nickel ferrite nanoparticles.

Fig. 17

Langmuir plot of Remazol Red dye adsorption onto nickel ferrite nanoparticles.

Fig. 18

Variation of the separation factor (RL) with initial concentration for the adsorption of Remazol Red dye onto nickel ferrite nanoparticles.

Fig. 19

Freundlich plot of Remazol Red dye adsorption onto nickel ferrite nanoparticles.

Fig. 20

Temkin plot of Remazol Red dye adsorption onto nickel ferrite nanoparticles.

Fig. 21

D-R plot of Remazol Red dye adsorption onto nickel ferrite nanoparticles.

Fig. 22

Recyclability of magnetic Nickel Ferrite NPs for Remazol Red dye removal.