RSM-CCD optimized adsorptive removal of p-Nitrophenol using Eco-Friendly magnetic activated carbon thin Film

p-nitrophenol (PNP) is a hazardous pollutant that poses significant risks to human health and ecosystems. This study developed a low-cost magnetic adsorbent, magnetically activated carbon thin film (MACTF) nanocomposite by modifying activated carbon thin film (ACTF) with Fe0/Fe3O4 nanoparticles for efficient PNP removal. Three nanocomposites (MACTF-1, MACTF-2, and MACTF-3) were synthesized with varying proportions of Fe0/Fe3O4. Characterization using XRD, TEM, FTIR, Raman, BET, BJH, and TGA confirmed the successful synthesis of the nanocomposites. MACTF-1 exhibited the highest BET surface area (346 m2/g) and total pore volume, making it the most effective adsorbent. The highest PNP removal rate (94 %) was attained under optimized parameters identified through the Response Surface Methodology (RSM) utilizing the Central Composite Design (CCD) method (pH: 4.5, PNP concentration: 69.5 mg.L−1, and contact time: 117.9 min). The adsorption process was best described by the Freundlich isotherm (R2 = 0.98, X 2 = 0.67) and fitted a pseudo-second-order kinetics (R2 = 0.99, X 2 = 0.09). Thermodynamic studies revealed that the adsorption was exothermic (ΔH˚ < 0) and spontaneous (ΔG˚ < 0) in nature. Reusability tests demonstrated that the adsorbent retained approximately 80 % removal efficiency after five consecutive cycles, highlighting its potential for practical applications. The study concludes that MACTF-1 is a highly effective, reusable, and easily separable adsorbent for PNP removal from aqueous environments.