Development and application of a poly (sodium p-styrenesulfonate-co-acrylic acid) / Ficus leaves–derived activated carbon composite for the efficient removal of 4-nitrophenol from aqueous solutions

Abstract This research details the synthesis and application of a novel poly (sodium p-styrenesulfonate-co-acrylic acid)/Ficus leaf–derived activated carbon composite (P(NaSS-co-AA)/AC) for the Efficient elimination of 4-Nitrophenol from contaminated Aqueous Solutions. The copolymer P(NaSS-co-AA) was fabricated via free-radical copolymerization of sodium p-styrenesulfonate (NaSS) and acrylic acid (AA) and characterized by GPC, ¹H NMR, and ¹³C NMR. The composite was further analyzed utilizing SEM, FTIR, BET, and TGA techniques. Batch adsorption tests experiments were performed to optimize operational parameters achieving optimal conditions at pH 7, an adsorbent dosage of 1.5 g/L, and a contact time of 120 min, with a removal efficiency of 95 ± 1.18%. Adsorption followed the Langmuir isotherm and pseudo-second-order kinetics, suggesting monolayer chemisorption on a homogeneous surface. The composite demonstrated high selectivity and robust performance in real wastewater matrices and multicomponent ionic environments, maintaining a removal efficiency of over 90% despite the presence of competing species. The maximum adsorption capacity was 65.0 ± 1.25 mg/g, exceeding conventional activated carbons. Statistical evaluation of models showed excellent fits (Langmuir R² = 0.994, RMSE = 0.85 ± 0.08; kinetics pseudo-second-order R² = 0.999, RMSE = 0.47 ± 0.04). Post-adsorption FTIR and XPS analyses confirmed 4-NP uptake and supported the proposed multi-mode adsorption mechanism (π–π stacking, electrostatic attraction, and hydrogen bonding). Preliminary column breakthrough experiments and leaching/environmental safety screening further validate the practical potential of this composite. These results showed that the developed composite is a sustainable and cost-effective adsorbent with strong potential for wastewater treatment applications targeting nitrophenol contaminants.