Fabrication and characterisation of magnetic graphene oxide incorporated Fe3O4@polyaniline for the removal of bisphenol A, t-octyl-phenol, and α-naphthol from water

Fabrication of molecularly imprinted resin via controlled polymerization applied in the enrichment of bisphenol A for plastic products

The addition of bisphenol A has been frequently used in industrial manufacturing because it imparts plastic products with characteristics such as transparency, durability, and excellent impact resistance. However, its widespread use raises concerns about potential leakage into the surrounding environment, which poses a significant risk to human health. In this study, molecularly imprinted polymers with specific recognition of bisphenol A were synthesized through surface-initiated atom transfer radical polymerization using poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) as the substrate, bisphenol A as the template molecule, 4-vinylpyridine as the monomer, and ethylene glycol dimethacrylate as the cross-linker. The bisphenol A adsorption capacity was experimentally investigated, and the kinetic analysis of the molecularly imprinted polymers produced an adsorption equilibrium time of 25 min, which is consistent with the pseudo-second-order kinetic model. The results of the static adsorption experiments exhibited consistency with the Langmuir adsorption model, revealing a maximum adsorption capacity of 387.2 μmol/g. The analysis of molecularly imprinted polymers-enriched actual samples using high-performance liquid chromatography demonstrated excellent selectivity for bisphenol A, with a linear range showing 93.4%-99.7% recovery and 1.1%-6.4% relative standard deviation, demonstrating its high potential for practical bisphenol A detection and enrichment applications.

Efficient removal of methylene blue from water using magnetic Alyssum homolocarpum seed gum-based matrix

In this study, we fabricated magnetic Fe₃O₄ nanoparticles conjugated with anionic hydroxypropyl starch-graft-acrylic acid (Fe3O4@AHSG) for the efficient removal of methylene blue (MB) dye from aqueous solutions. The synthesized nanoconjugates were characterized using various techniques. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analysis revealed that the particles exhibited homogeneously distributed nanosized spherical shapes with a mean diameter of 41.72 ± 6.81 nm. The EDX analysis confirmed the absence of impurities, with the Fe₃O₄ particles comprising 64.76 % iron and 35.24 % atomic oxygen. Dynamic light scattering (DLS) measurements showed a monodisperse particle system with a mean hydrodynamic size of 135.4 nm (polydispersity index, PI = 0.530) for the Fe₃O₄ nanoparticles and 163.6 nm (PI = 0.498) for the Fe3O4@AHSG adsorbent. Vibrating sample magnetometer (VSM) analysis indicated superparamagnetic behavior for both Fe₃O₄ and Fe₃O₄@AHSG, with higher saturation magnetization (Ms) observed for Fe₃O₄. The dye adsorption studies demonstrated that the adsorbed dye capacity increased with increasing initial MB concentration and adsorbent dose. The pH of the dye solution significantly influenced the adsorption, with the highest adsorption observed at basic pH values. The presence of NaCl reduced the adsorption capacity due to increased ionic strength. Thermodynamic analysis indicated the thermodynamically favorable and spontaneous nature of the adsorption process. Kinetic studies revealed that the pseudo-second-order model provided the best fit to the experimental data, suggesting chemisorption as the rate-limiting step. Overall, Fe₃O₄@AHSG nanoconjugates exhibited excellent adsorption capacity and could be a promising material for effective removal of MB dye from wastewater.

Potentiometric Performance of Ion-Selective Electrodes Based on Polyaniline and Chelating Agents: Detection of Fe2+ or Fe3+ Ions

We constructed a sensor for the determination of Fe²⁺ and/or Fe³⁺ ions that consists of a polyaniline layer as an ion-to-electron transducer; on top of it, chelating molecules are deposited (which can selectively chelate specific ions) and protected with a non-biofouling poly(2-methyl-2-oxazoline)s layer. We have shown that our potentiometric sensing layers show a rapid response to the presence of Fe²⁺ or Fe³⁺ ions, do not experience interference with other ions (such as Cu²⁺), and work in a biological environment in the presence of bovine serum albumin (as a model serum protein). The sensing layers detect iron ions in the concentration range from 5 nM to 50 µM.

Development of amine-functionalized superparamagnetic iron oxide nanoparticles anchored graphene nanosheets as a possible theranostic agent in cancer metastasis

The major objective of the present investigation was to assess the targeting potential of a designed system for breast cancer at metastatic phases with imaging ability. In a nutshell, we have developed surface-engineered graphene oxide (GO) nanosheets by covalent linking with amine-functionalized iron oxide nanoparticles (IONPs) (GOIOIs). Gefitinib (Gf) was selected as a model drug and entrapped in between exfoliated GO sheets (GOIGF) via π-π* stacking before functionalization with IONPs. Preliminary characterization of GO, IONPs, GOIOI, and GOIGF was performed using UV-visible and Fourier transform infrared spectroscopy. Scanning and transmission electron microscopy studies confirmed successful surface engineering of GO with IONPs. The in vitro drug release study demonstrated sustained release of Gf. The magnetic behavior of IONPs and GOIOI demonstrated a sigmoidal-shaped hysteresis loop with superparamagnetic properties. The in vitro cell cytotoxicity assay was carried out on MDA-MB-231 breast cancer adenocarcinoma cell lines. The cell cytotoxicity assay showed 61.18% inhibition of cell growth with 30 ppm concentration containing 64% of the drug, whereas 100% of the pure drug revealed only 56% of inhibition. In the near future, GOIOI could be tailored further for theranostic research, especially for metastatic cancers. Graphical abstract.

Fe3O4@PANI: a magnetic polyaniline nanomaterial for highly efficient and handy enrichment of intact N-glycopeptides

Glycosylation of proteins plays important roles in the occurrence and development of chronic diseases. In this study, we report an enrichment method of intact N-glycopeptides using a magnetic polyaniline nanomaterial (Fe₃O₄@PANI). Under the synergistic effect of hydrogen bonding and electrostatic adsorption, Fe₃O₄@PANI can rapidly and easily enrich N-glycopeptides derived from standard protein (bovine fetuin and transferrin) tryptic digests and serum haptoglobin tryptic digests. Finally we have detected 63 glycopeptides in the glycosylation sites of both N204 and N211 from the serum haptoglobin beta chain using MALDI FTICR MS. Compared with non-magnetic materials, Fe₃O₄@PANI can achieve complete separation from complex biological samples, meeting the requirement of the high purity of samples for mass spectrometric detection. Overall, Fe₃O₄@PANI exhibits great application potential in the highly efficient enrichment of intact N-glycopeptides due to its stability and convenient preparation.

Advanced Functional Nanostructures based on Magnetic Iron Oxide Nanomaterials for Water Remediation: A Review

The fast growth of industrialization combined with the increasing population has led to an unparalleled demand for providing water in a safe, reliable, and cost-effective way, which has become one of the biggest challenges of the twenty-first century faced by global society. The application of nanotechnology in water treatment and pollution cleanup is a promising alternative in order to overcome the current limitations. In particular, the application of magnetic iron oxide nanoparticles (MIONs) for environmental remediation has currently received remarkable attention due to its unique combination of physicochemical and magnetic properties. Given the broadening use of these functional engineered nanomaterials, there is a growing concern about the adverse effects upon exposure of products and by-products to the environment. This makes vitally relevant the development of green chemistry in the synthesis processes combined with a trustworthy risk assessment of the nanotoxicity of MIONs as the scientific knowledge of the potential hazard of nanomaterials remains limited. This work provides comprehensive coverage of the recent progress on designing and developing iron oxide-based nanomaterials through a green synthesis strategy, including the use of benign solvents and ligands. Despite the limitations of nanotoxicity and environmental risks of iron oxide-based nanoparticles for the ecosystem, this critical review presents a contribution to the emerging knowledge concerning the theoretical and experimental studies on the toxicity of MIONs. Potential improvement of applications of advanced iron oxide-based hybrid nanostructures in water treatment and pollution control is also addressed in this review.

An Overview and Evaluation of Highly Porous Adsorbent Materials for Polycyclic Aromatic Hydrocarbons and Phenols Removal from Wastewater

Polycyclic aromatic hydrocarbons (PAHs) and phenolic compounds had been widely recognized as priority organic pollutants in wastewater with toxic effects on both plants and animals. Thus, the remediation of these pollutants has been an active area of research in the field of environmental science and engineering. This review highlighted the advantage of adsorption technology in the removal of PAHs and phenols in wastewater. The literature presented on the applications of various porous carbon materials such as biochar, activated carbon (AC), carbon nanotubes (CNTs), and graphene as potential adsorbents for these pollutants has been critically reviewed and analyzed. Under similar conditions, the use of porous polymers such as Chitosan and molecularly imprinted polymers (MIPs) have been well presented. The high adsorption capacities of advanced porous materials such as mesoporous silica and metal-organic frameworks have been considered and evaluated. The preference of these materials, higher adsorption efficiencies, mechanism of adsorptions, and possible challenges have been discussed. Recommendations have been proposed for commercialization, pilot, and industrial-scale applications of the studied adsorbents towards persistent organic pollutants (POPs) removal from wastewater.

Eco-friendly alginate encapsulated magnetic graphene oxide beads for solid phase microextraction of endocrine disrupting compounds from water samples

In the proposed method iron crosslinked alginate encapsulated magnetic graphene oxide beads were synthesized and used as an adsorbent for the microextraction of endocrine disrupting compounds from water samples and further analyzed by high performance liquid chromatography with ultraviolet detector. The beads were characterized using spectroscopic techniques, such as Fourier transform infra-red spectroscopy for the determination of different functional groups, Scanning electron microscopy for surface morphology, X-ray diffraction for phase determination and energy dispersive X ray spectroscopy for elemental composition. The results revealed that beads surface have functional groups of alginate and graphene oxide which are involved in π-π, n-πinteractions and hydrogen bonding for the bisphenol A and epichlorohydrin adsorption. The experimental conditions were studied for two endocrine disrupting compounds (Epichlorohydrin ad Bisphenol A) and at optimum conditions the adsorption capacity was 6.73 mgg^-1 for epichlorohydrin and 7.01 mgg^-1 for bisphenol A. The kinetic and equilibrium studies revealed that the adsorption process follow pseudo-second order kinetics and Langmuir equilibrium models. Analytical parameters were calculated for the microextraction of epichlorohydrin and bisphenol A. Limit of detection was 8.25 ngL^-1 and 13.99 ngL^-1 (n = 4) for epichlorohydrin and bisphenol A, respectively. Different solvents used for microextraction and maximum extraction of both endocrine disrupting compounds were obtained with methanol. The proposed method was applied to spiked samples and the recovery values were 97.17 ± 3.13% for epichlorohydrin and 99.46 ± 1.39% for bisphenol A. The magnetic graphene oxide encapsulated inside an alginate shows nontoxic green chemical with high extraction performance for toxic organic compounds in water treatment.

Magnetic nanostructures for preconcentration, speciation and determination of chromium ions: A review

Magnetic nanoparticles based solid-phase extraction is a new analytical technique based on the use of magnetic sorbents for the preconcentration and quantification of different inorganic and organic species. The present review concentrates on recent developments that have been built in magnetic nanostructures-based solid phase extraction, speciation and quantification of chromium ions. Besides, a description of the preparation, characterization as well as applications of various types of magnetic nanostructures, either with an inorganic or organic coating of the magnetic core, is presented. In addition, the most important analytical characteristics such as preconcentration factor, linear range, and limits of detection were carefully reported and compared. On the other hand, the removal of the chromium ions by magnetic solid phase extraction was not discussed in the review.

Controlling the transverse proton relaxivity of magnetic graphene oxide

The engineering of materials with controlled magnetic properties by means other than a magnetic field is of great interest in nanotechnology. In this study, we report engineered magnetic graphene oxide (MGO) in the nanocomposite form of iron oxide nanoparticles (IO)-graphene oxide (GO) with tunable core magnetism and magnetic resonance transverse relaxivity (r₂). These tunable properties are obtained by varying the IO content on GO. The MGO series exhibits r₂ values analogous to those observed in conventional single core and cluster forms of IO in different size regimes-motional averaging regime (MAR), static dephasing regime (SDR), and echo-limiting regime (ELR) or slow motion regime (SMR). The maximum r₂ of 162 ± 5.703 mM^-1s^-1 is attained for MGO with 28 weight percent (wt%) content of IO on GO and hydrodynamic diameter of 414 nm, which is associated with the SDR. These findings demonstrate the clear potential of magnetic graphene oxide for magnetic resonance imaging (MRI) applications.

Highly visible-light-responsive Cu2O/rGO decorated with Fe3O4@SiO2 nanoparticles as a magnetically recyclable photocatalyst

The rhombic dodecahedral cuprous oxide-reduced graphene oxide/core-shell Fe₃O₄@SiO₂ composites (denoted as rCu₂O-rGO/Fe₃O₄@SiO₂) are successfully synthesized facilely via a wet-chemical route. The resulting rCu₂O-rGO/Fe₃O₄@SiO₂ combines the unique structure of Cu₂O, electronic characteristics of reduced graphene oxide (rGO) and magnetic property of Fe₃O₄@SiO₂ to be an effective and recoverable photocatalyst for the degradation of methyl orange (MO). The obtained results show that rCu₂O-rGO/Fe₃O₄@SiO₂ is capable of completely degrading MO in the presence of a very low catalyst concentration (0.125 g l^-1) within a short time (60 min) under visible light compared to the reported catalysts. The observations may be due to the distinctive interfacial structures of rhombic dodecahedral Cu₂O nanoparticles connected to rGO sheets that can enhance the separation of photogenerated electron-hole pairs, stabilize the Cu₂O and increase MO adsorption, as evidenced by a variety of spectroscopic analyses (transmission electron microscopy, x-ray photoelectron spectroscopy and photoluminescence). More importantly, these efficient photocatalysts can easily be recovered under a magnetic field and remain highly photoactive towards the degradation of MO after cyclic tests, and may be promising photocatalysts for practical applications in the solar-energy purification of wastewater.

Functionalized magnetic nanoparticles: Synthesis, characterization, catalytic application and assessment of toxicity

Cost-effective water cleaning approaches using improved treatment technologies, for instance based on catalytic processes with high activity catalysts, are urgently needed. The aim of our study was to synthesize efficient Fenton-like photo-catalysts for rapid degradation of persistent organic micropollutants in aqueous medium. Iron-based nanomaterials were chemically synthesized through simple procedures by immobilization of either iron(II) oxalate (FeO) or iron(III) citrate (FeC) on magnetite (M) nanoparticles stabilized with polyethylene glycol (PEG). Various investigation techniques were performed in order to characterize the freshly prepared catalysts. By applying advanced oxidation processes, the effect of catalyst dosage, hydrogen peroxide concentration and UV-A light exposure were examined for Bisphenol A (BPA) conversion, at laboratory scale, in mild conditions. The obtained results revealed that BPA degradation was rapidly enhanced in the presence of low-concentration H₂O₂, as well as under UV-A light, and is highly dependent on the surface characteristics of the catalyst. Complete photo-degradation of BPA was achieved over the M/PEG/FeO catalyst in less than 15 minutes. Based on the catalytic performance, a hierarchy of the tested catalysts was established: M/PEG/FeO > M/PEG/FeC > M/PEG. The results of cytotoxicity assay using MCF-7 cells indicated that the aqueous samples after treatment are less cytotoxic.