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Water pollution caused by cationic dyes such as crystal violet (CV) poses a serious environmental concern due to their toxicity and persistence. Physically activated carbon (p-AC) is widely used as an effective adsorbent; however, it exhibits limitations in terms of separation and regeneration. Modification with magnetite nanoparticles (Fe₃O₄NPs) can enhance separation efficiency, but often leads to particle agglomeration that blocks active adsorption sites. Therefore, Moringa oleifera leaf extract (MoE) was employed as a reducing, stabilizing, and anti-agglomeration agent in the synthesis process. This study aims to synthesize a magnetite–carbon nanocomposite (Fe₃O₄NPs@C) via a green bioassisted approach and evaluate its performance for CV adsorption. The nanocomposite was prepared by dispersing Fe₃O₄NPs onto a p-AC matrix in the presence of MoE as a multifunctional agent. Characterization using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy Energy Dispersive X-ray Spectroscopy (SEM–EDX), Transmission Electron Microscopy (TEM), Particle Size Analysis (PSA), Brunauer Emmett Teller (BET) Surface Area analysis, and pH at the point of zero charge (pHₚzc) confirmed the successful formation of Fe₃O₄NPs@C with structural and surface properties suitable for adsorption. The results showed that optimal conditions were achieved at pH 8 with an equilibrium time of 120 min at 25 °C. Kinetic and isotherm analyses indicated that adsorption follows a pseudo-second-order model and the Langmuir isotherm, suggesting a monolayer chemisorption mechanism, with a maximum adsorption capacity (qₘ) of 35.84 mg g −1 . Furthermore, the adsorbent exhibited magnetic properties that enabled rapid separation and maintained more than 50% removal efficiency after 13 adsorption desorption cycles. These results demonstrate that MoE assisted Fe₃O₄NPs@C not only improves the separation of carbon-based adsorbents but also mitigates nanoparticle agglomeration, making it a promising, environmentally friendly, and practical adsorbent for dye wastewater treatment.
Zulaicha et al. (Fri,) studied this question.