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The environmental pollution, particularly water pollution, has gradually caused severe human health issues. Organic dyes are one of the most emerging pollutants in the environment. In the present study, graphene oxide (GO) was functionalized with chitosan (CS) and magnetic nanoparticles (Fe-NPs) and tested to remove Sudan I, II, III, and IV dyes from water. The synthesized GO-CS-Fe was characterized using UV–vis, SEM, TEM, EDX, and FTIR spectroscopy, and confirmed the structural composition of nanocomposite, with the Fe-NPs dimension over the GO-CS surface to be 31–44 nm. The effects of various experimental factors; time,pH, adsorbent amount, dyes concentrations, and temperature were executed using the batch experiment. The experimental data were fitted to pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich kinetic models. The isotherm models parameters of the Langmuir, Freundlich, Redlich–Peterson, Temkin, and Hill isotherms, along with the thermodynamics parameters were also calculated. The data was explained by the Langmuir isotherm model with maximum adsorption capacities for Sudan I, II, III, and IV as 360.6, 353.7, 351.0, and 347.6 mg/g, respectively. The rapid uptake of the dyes fitted the pseudo-second-order kinetic, asserting that the adsorption was diffusion controlled. The process was spontaneous and endothermic in nature. The reusability study of GO-CS-Fe was performed up to five cycles. The nanocomposite can retain its efficacy even after the considered cycles. In conclusion, the GO-CS-Fe nanocomposite has exhibited a high potential for removing Sudan dyes from the aqueous solution due to its high adsorption and regeneration capability. [ABSTRACT FROM AUTHOR]

A tryptophan ionic liquid (TrpIL) decorated magnetic graphene oxide (Fe3O4@SiO2-GO-TrpIL) nanocomposite has been prepared for magnetic solid-phase extraction of Sudan I–IV before their high performance liquid chromatography (HPLC) analysis. Fe3O4@SiO2 nanoparticles loaded on graphene oxide endow the as-prepared nanocomposite with superparamagnetic performance, benefiting conveniently magnetic separation of the Sudan-absorbed nanocomposites from an aqueous phase. Both TrpIL and grapheme oxide make the Fe3O4@SiO2-GO-TrpIL adsorbent possess high affinity and extraction efficiency toward target analytes, Taking full advantages of the adsorbent, each of Sudan I–IV could be accurately quantified in a linear range of 0.01–0.50 µg mL−1 with the detection limit of 1.0 ng mL−1 under the optimized conditions. A 10-fold enrichment factor was obtained. The present method was employed for the simultaneous determination of Sudan I–IV in chill and water samples with satisfactory results. The thermodynamic and kinetic investigations proved that the targets might be chemisorbed onto the Fe3O4@SiO2-GO-TrpIL nanocomposite. [ABSTRACT FROM AUTHOR]