Iron–Carbon Hybrid Magnetic Nanosheets for Adsorption-Removal of Organic Dyes and 4-Nitrophenol from Aqueous Solution

Here, we report a nonprecious mesoporous adsorbent obtained from the carbonization of bagasse. The material shows an impressive pH-dependent adsorbent property for cationic, anionic, and commercially used dyes along with an organic contaminant (4-nitrophenol) in water. The adsorbent shows specific surface area of ∼462 m2 g–1 and the porous layered structure as confirmed by gas adsorption and microscopic techniques, respectively. Further, pH triggered adsorption of methylene blue (MB, cationic dye), Congo red (CR, anionic dye), and commercial hair dye were studied. The results show >96% adsorption for CR and MB within 24 min at pH 2 and pH 8, respectively. Moreover, fast adsorption response, 92.6% in 20 min, was obtained for a commercially used hair dye and demonstrates the practical applicability of the material for wastewater remediation. Under experimental conditions, adsorbent shows ultrafast adsorption kinetics (4 min to achieve equilibrium state with 99.5% adsorption) for 4-nitrophenol from water. Notably, the adsorbent shows structural stability, easily separable with an external magnetic field, and recyclability with ∼85% efficiency even after the fifth cycle.