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The present work reports the synthesis of MgCo2O4-rGO nanohybrid by a simple method. The nanohybrid was characterised by XRD, Raman spectroscopy, EDX, SEM, and TEM. An effective electrochemical sensing platform to detect Sudan I based on MgCo2O4-rGO nanohybrid modified screen-printed electrode (MgCo2O4-rGO/SPE) is reported. Electrocatalytic sensing of Sudan I is carried out using cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CHA) as well as differential pulse voltammetry (DPV) measurements. Interestingly, this newly developed sensor showed greater peak currents with the decreased anodic potential than that of the bare SPE. The modified electrode demonstrated distinctive electrocatalytic activities to detect Sudan I with the longer linear response range between 0.04 and 580.0 µM, low limit of detection (LOD) of 9.0 nM, and high sensitivity of 0.0838 µA µM−1. In addition, MgCo2O4-rGO/SPE sensor exhibited excellent electrochemical stability, repeatability and reproducibility for Sudan I detection. Analytical utility of our method revealed acceptable detection outputs for Sudan I. Therefore, it could be concluded that this sensor (MgCo2O4-rGO/SPE) exhibited very good electrochemical behaviour for electrochemical detection of Sudan I oxidation. [ABSTRACT FROM AUTHOR]

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]

We developed a new sensor based on spinel zinc ferrite nanoparticles (ZnFe2O4) and reduced graphene oxide (RGO) decorated electrode, or ZnFe2O4/RGO nanocomposite, which characterized with various techniques, including Raman spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results showed admirable crystallinity and large surface area for the proposed electrode. Moreover, a screen printed electrode (SPE) was modified with ZnFe2O4/RGO nanocomposite (ZnFe2O4/RGO/SPE) for detection of Sudan I sensitively and selectively. Sudan I electrochemical responses appeared in acceptable shape with several symmetric cyclic voltammetric peaks, followed by calculating electrochemical factors. In addition, differential pulse voltammetry confirmed the Sudan I oxidation response with high sensitivity. The plot of oxidation peak currents versus different concentrations of Sudan I using a linear regression analysis was drawn to determine the Sudan I electroanalysis under optimized conditions. The results exhibited a low limit of detection (0.02 μM) and a broad linear dynamic range (0.07–415.0 μM). [ABSTRACT FROM AUTHOR]

In recent times, due to their diverse applications, novel bioengineered green magnetic nanomaterials have attracted much interest. In this report, we demonstrated the fabrication and stepwise synthesis of pomegranate peel extract (PPE) modified GO-CuFe 2 O 4 nanocomposite as an advanced functional nanocomposite (PPE@GO-CuFe 2 O 4). We aimed to utilize the phenolic acid phytochemicals in the catalytic process. The novel material was physicochemically characterized using several techniques. The as-developed nanocomposite was explored catalytically in the green synthesis of biodiesel from rapeseed oil by transesterification method. Subsequently, the catalyst was used in the simultaneous determination of toxic organic azo dye food colorants Sudan 1 and 2 in environmental waters using liquid chromatography, and exhibited excellent activity. Being magnetic cored, the nanocatalyst was easily retrieved magnetically and was recycled several times with little change in catalytic activity. • The novel, green nanocomposite was prepared and characterized by a range of advanced techniques. • The material was explored as catalyst in the production of biodiesel and environmental remediation. • The material was recovered easily and reused several times without significant loss of catalytic activity. [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]