Graphene Fe3O4 Research Articles

Synthesis of superparamagnetic Fe3O4–graphene oxide-based material for the photodegradation of clonazepam

The global concern over water pollution caused by contaminants of emerging concern has been the subject of several studies due to the complexity of treatment. Here, the synthesis of a graphene oxide-based magnetic material (GO@Fe3O4) produced according to a modified Hummers’ method followed by a hydrothermal reaction was proposed; then, its application as a photocatalyst in clonazepam photo-Fenton degradation was investigated. Several characterization analyses were performed to analyze the structure, functionalization and magnetic properties of the composite. A 23 factorial design was used for the optimization procedure to investigate the effect of [H2O2], GO@Fe3O4 dose and pH on clonazepam degradation. Adsorption experiments demonstrated that GO@Fe3O4 could not adsorb clonazepam. Photo-Fenton kinetics showed that total degradation of clonazepam was achieved within 5 min, and the experimental data were better fitted to the PFO model. A comparative study of clonazepam degradation by different processes highlighted that the heterogeneous photo-Fenton process was more efficient than homogeneous processes. The radical scavenging test showed that O2·-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${O}_{2}^{\\cdot -}$$\\end{document} was the main active free radical in the degradation reaction, followed by hydroxyl radicals (•OH) and holes (h+) in the valence layer; accordingly, a mechanism of degradation was proposed to describe the process.

Adsorption of fast green dye onto Fe3O4 MNPs and GO/Fe3O4 MNPs synthesized by photo-irradiation method: Isotherms, thermodynamics, kinetics, and reuse studies

In this study, the adsorption of Fast Green dye (FGD) on the surface of ferrous ferric oxide Fe3O4 MNPs and Graphene oxide Nano-Sheets/ferrous ferric oxide GO/Fe3O4 MNPs as adsorbents was examined. The photo-irradiation method was successfully used to synthesize Fe3O4 MNPs and GO/Fe3O4 MNPs using UV lamp. Raman spectroscopy was used to characterize the GO and GO/ Fe3O4 MNPs. XRD, FESEM, and EDX were used to characterize the Fe3O4 MNPs and GO/ Fe3O4 MNPs. Optimal adsorption conditions were studied, including a contact time of 60 min, MNPs amount of 0.05 g, pH 2, FGD concentration of 10 mg/L, and temperature of 308 K. Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich (D-R) isotherm models were used to fit the experimental equilibrium data at five different temperatures (288, 298, 308, 318, and 328 K). It was noticed that FGD adsorption on Fe3O4 MNPs and GO/ Fe3O4 MNPs is consistent with the Freundlich model at 308 K. The PSO rate kinetics suggests that both MNPs are promising materials for the removal of FGD from aqueous solutions. Thermodynamic studies showed that the adsorption processes are non-spontaneous on both MNPs surfaces, endothermic for Fe3O4 MNPs, and exothermic for GO/ Fe3O4 MNPs. All the results confirm that Fe3O4 MNPs and GO/ Fe3O4 MNPs have the potential to be efficient, low-cost, reusable, and stable adsorbents for the removal of FGD from aqueous solutions.

Electrochemical Detection of a Breast Cancer Biomarker with an Amine-Functionalized Nanocomposite Pt-Fe3O4-MWCNTs-NH2 as a Signal-Amplifying Label.

We report an ultrasensitive sandwich-type electrochemical immunosensor to detect the breast cancer biomarker CA 15-3. Amine-functionalized composite of reduced graphene oxide and Fe3O4 nanoparticles (MRGO-NH2) was used as an electrochemical sensing platform material to modify the electrodes. The nanocomposite comprising Pt and Fe3O4 nanoparticles (NPs) anchored on multiwalled carbon nanotubes (Pt-Fe3O4-MWCNTs-NH2) was utilized as a pseudoenzymatic signal-amplifying label. Compared to reduced graphene oxide, the composite MRGO-NH2 platform material demonstrated a higher electrochemical signal. In the Pt-Fe3O4-MWCNTs-NH2 label, multiwalled carbon nanotubes provided the substratum to anchor abundant catalytic Pt and Fe3O4 NPs. The nanocomposites were thoroughly characterized using transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. An electroanalytical study and prevalidation of the immunosensor was carried out. The immunosensor exhibited exceptional capabilities in detecting CA 15-3, offering a wider linear range of 0.0005-100 U mL-1 and a lower detection limit of 0.00008 U mL-1. Moreover, the designed immunosensor showed good specificity, reproducibility, and acceptable stability. The sensor was successfully applied to analyze samples from breast cancer patients, yielding reliable results.

High-efficiency electromagnetic shielding based on multipolar effect in RGO/MXene aerogels decorated with ordered Fe3O4 cluster

With the widespread use of digital systems and electronic communication devices, there is an urgent need to develop lightweight and efficient electromagnetic interference (EMI) shielding materials to address the growing problem of radiation pollution. RGO/MXene/Fe3O4 aerogels were successfully designed and synthesised using a one-step hydrothermal process induced by an external magnetic field in this study. Reduced graphene RGO, MXene nanosheets and Fe3O4 nanoparticles were suitably assembled together to achieve the combined advantages. The aerogels exhibited large specific surface area and hierarchical porosity. The material not only achieves an effective synergy between magnetic loss and dielectric loss, but also exhibits satisfactory EMI shielding performance. Magnetic field induced RGO/MXene/Fe3O4 aerogels (MIRMFE-2) exhibits the best EMI shielding performance with an average SET value of 76.9 dB. The excellent shielding performance of MIRMFE is attributed to both its 3D porous structure and the high dielectric loss due to multiple polarization relaxation, magnetic loss due to eddy current loss and natural resonance. The synthesis of MIRMFE provides an effective method for, designing high-performance and lightweight EMI shielding materials.

Continuous flowing polarization system containing absorbents for acceleration of absorption of oil-in-water micelles in water by electric dipole moments

The concentration gradient between solution to absorbent predominately determines the absorption and desorption rates, limited the efficiency of wastewater treatment at low pollutant concentration. Dielectrophoresis force (FDEP) is generated with polarization to assemble the absorbents and oil-in-water micelles (OWM) in a home-made parallel plate capacitor (PPC) full of adsorbent solution and enhance the efficiency of pollutant removal. Graphene oxide (GO) and Fe3O4 nanoparticles (FN) are coated on polystyrene microspheres (PSs) as the core/shell PS/GO/FN absorbents that were encapsulated within the PPC to treat the solution of OWM. The FDEP enhances the adsorption rate ca. 2–4 times with polarization at 14 V and 100 kHz. 50 % volume reducing of pure water through the PPC for the recycling of the absorbents could achieve at 1200 kHz. The high complex permittivity of the GO/FN coating facilitates the response to the alternative electric field to induce the dipoles in the object without significant damage. The PS/GO/FNs was reused ca. 10 times at 25 mL min−1 of flow rate through the PPC between 100 and 1200 kHz. The continuous dielectric polarization system improves the absorption rates and efficiency of absorbent recycling with low secondary pollution.

Fe3O4/carbon-decorated graphene boosts photothermal conversion and storage of phase change materials

Pristine organic phase change materials (PCMs) are difficult to complete photothermal conversion and storage. To upgrade their photothermal conversion and storage capacity, we developed Fe-MOF (metal-organic framework) derived Fe3O4/C-decorated graphene (GP) based composite PCMs toward solar energy harvesting. Graphene is an excellent phonon conductor, and Fe3O4/C-GP as a photon capturer exhibits strong full-spectrum absorption. Additionally, Fe-MOF derived Fe3O4 nanoparticles are anchored on graphene nanosheets to reduce interfacial thermal resistance, shorten thermal diffusion path, and accelerate phonon transport. After the encapsulation of octadecanol (ODA) in Fe3O4/C-GP, ODA@Fe3O4/C-GP composite PCMs yield a high photothermal conversion efficiency of 88.18 % under 0.12 W/cm2 benefiting from the synergistic effect of 3D interconnected graphene framework and Fe3O4 nanoparticles with localized surface plasmon resonance effect. Moreover, ODA@Fe3O4/C-GP composite PCMs exhibit excellent latent heat storage stability, photothermal conversion stability and durable reliability after undergoing multiple cycle evaluation, boosting high-efficiency utilization of solar energy.

Fabrication of magnetic nanocomposite scaffolds based on polyvinyl alcohol-chitosan containing hydroxyapatite and clay modified with graphene oxide: Evaluation of their properties for bone tissue engineering applications

One of the most common systems for bone tissue engineering is polymeric scaffolds. However, the low mechanical properties of polymeric scaffolds, considering the properties required for bone replacement tissue, are the main challenge for researchers in this field. For bone tissue engineering, this research prepared nanocomposite scaffolds based on polyvinyl alcohol-chitosan containing modified clay and hydroxyapatite (HAp). HAp used in these 3D scaffolds was synthesized from a chicken femur, and Cloisite 30B clay nanoparticles were modified by graphene oxide and Fe3O4 nanoparticles to strengthen their mechanical properties. Sample characteristics were determined using FT-IR, XRD, SEM, TGA, swelling rate, laboratory degradation, and biological and mechanical properties. These analyses showed that 2% of modified clay (C30B/GO/Fe3O4, CGF) inside the nanocomposite scaffold increased the compressive strength 23 times compared to the pristine polymer scaffold. Also, adding HAp particles and modified clay simultaneously increased the mineralization on the surface of the scaffolds. Final nanocomposite scaffolds were found to have a compressive strength of 9.31 MPa, a porosity of 75 %, and a porosity size of 50 nm and were in the range of cancellous bone. The final swelling amount is 1790 %, which is the amount that is Favorable for bone scaffold. Finally, the analysis results to determine the samples' toxicity showed that none of the prepared scaffolds were toxic and showed good cell viability.

Towards an efficient oxidation of sulfides to sulfoxides over magnetic and grafted polyoxometalate on graphene oxide nanosheets

In this study, a tri-component composite consisting of Fe3O4 nanoparticles, Keggin-type polyoxometalate, and graphene oxide components was prepared using an ultrasonic-assisted method. The resulting Fe3O4/SiW12/GO composite was successfully characterized using multiple methods. The performance of the Fe3O4/SiW12/GO composite as a heterogeneous catalyst for the oxidation of sulfides to sulfoxides was investigated under mild conditions, with H2O2 serving as the oxidant. The catalyst exhibited excellent stability and high yields, completing the conversions within one hour. Furthermore, the Fe3O4/SiW12/GO catalyst demonstrated remarkable recyclability, as it could be recovered and reused up to four times without any significant loss in activity. This finding was supported by the results obtained from the ICP-OES analysis, which confirmed the negligible leaching of the active site. One of the key advantages of the Fe3O4/SiW12/GO catalyst is its heterogeneous nature, which allows for its rapid recovery from the reaction mixture. Additionally, it offers smooth and clean reaction conditions at room temperature, making it an innovative and cost-effective choice for accelerating reaction times. In summary, the Fe3O4/SiW12/GO composite represents a highly efficient and versatile heterogeneous catalyst with a unique structure. Its exceptional stability, high yields, and recyclability make it a superior choice for various organic–inorganic hybrid catalytic reactions conducted under mild conditions.

Efficient Removal of Representative Chemical Agents by Rapid and Sufficient Adsorption via Magnetic Graphene Oxide Composites

Chemical agents pose a significant threat to social security, highlighting the crucial role of representative chemical agents adsorption in ensuring the safety our environment. This study explored the application of Magnetic Graphene Oxide Nanoplatelet Composites (MGONCs) in adsorbing the representative chemical agents such as Lewisite (L), O-ethyl S-2-diisopropylaminoethyl methylphosphonothiolate (VX), Sarin (GB), and Soman (GD). MGONCs were synthesized through a physical blending method, with the combination of graphene oxide (GO) and Fe3O4 nanoparticles at a mass ratio of 1:1. Optimization of the adsorption process involved investigating the effects of contact time, temperature, and adsorbent dosage. Remarkably, the adsorption rate of L and VX exceeded 99% when the dosage of MGONCs was 2.5 mg, with a contact time of 30 s at room temperature. Furthermore, GB and GD achieved maximum adsorption rates after a contact time of 20 min, with the dosages of MGONCs at 10 mg and 20 mg, respectively. Characterization of the magnetic composite was accomplished through XRD, TEM, VSM, FTIR, TGA, and BET analyses. Kinetical analysis revealed that the adsorption mechanism of GB and GD on MGONCs followed pseudo-second-order (PSO) kinetics, exhibiting a high regression coefficient. The calculated qe values were 0.103125 mg/g and 0.081349 mg/g, respectively. This research demonstrated the feasibility of utilizing MGONCs as highly efficient adsorbents for representative chemical agents, particularly in on-site sampling scenarios.

Fe3O4–graphene/polyethylene glycol–SiO2 as a phase change material for thermal energy storage

Renewable energy efficiency can be increased using phase change materials (PCMs). This study has successfully developed PCMs with supporting materials, such as SiO2, Fe3O4, and graphene. Briefly, the synthesis of Fe3O4–Graphene/polyethylene glycol (PEG)–SiO2 begins with the synthesis of Fe3O4–Graphene using the coprecipitation method. Next, Fe3O4–Graphene/PEG–SiO2 nanocomposites are prepared with Fe3O4–Graphene mass varied in a range of 5%–8%. Based on the results, the Eg value of the Fe3O4–Graphene is 1.73 eV. The morphology of Fe3O4–Graphene/PEG–SiO2 shows that Fe3O4 particles stick to the surface of the graphene sheet. The addition of Fe3O4–Graphene mass affects the saturation magnetization value, which increases with an increase in Fe3O4–Graphene within the range of 1.05–2.55 emu/g. In addition, the latent calorific value obtained by differential scanning calorimetry shows that all the samples have a phase transition range within a temperature range of 59.4°C-60.5 °C and a latent calorific value of >100 J/g. Owing to its high latent calorific value, Fe3O4–Graphene/PEG–SiO2 can be applied as a heat-storage material.

A new approach to electrochemical sensing of a wildly used antibiotic; ciprofloxacin

Excessive use of antibiotics has conducted to a substantial enhancement in drug-resistant genes. Hence, introducing efficacious devices for antibiotic monitoring can ameliorate the life quality. Thus, a valid feasible sensor was developed for ciprofloxacin (CIP) determination using the synergistic interaction of graphene nanosheets (GR NSs) and Fe3O4 nanoparticles (Fe3O4NPs) in the matrix of carbon paste electrode (CPE). Field emission scanning electron microscope (FESEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) techniques were utilized to evaluate the sensor’s electrochemical features. As a result of the excellent properties of the applied nanostructures, the prepared sensor exhibited enhanced electrocatalytic activity. Quantitative analysis of CIP also provided detection and quantification limits of 1.8 nM and 6 nM, respectively. Moreover, the selectivity, sensitivity, stability, repeatability, and reproducibility were successfully examined. These desirable outcomes along with the extraordinary performance of GR/Fe3O4NPs/CPE in real samples promise to provide a reliable device in food and environmental applications.

Facile fabrication of bioinspired hierarchical porous MOFs for selective adsorption of Congo red and Malachite green from vegetables and fruits juices

The dye pollution in environmental water and food caused by industrial production and illegal addition is a serious problem worldwide, which endangers ecosystem, food safety and human health. To effectively overcome these challenges, a magnetic bioinspired hierarchical porous MOFs (BHP-MOFs) based on ZIF-8, Fe3O4 and three-dimensional graphene was successfully prepared for selective adsorption of Congo red (CR) and Malachite green (MG) from aqueous solutions. The surface morphology, physicochemical structure and composition of BHP-MOFs were characterized by SEM, TEM, FT-IR, XRD, Zeta potential, TGA and VSM analysis. The prepared BHP-MOFs exhibited a large specific surface area (225.522 m2/g), high pore volume (0.248 cm 3/g) and superparamagnetism, which made it an efficient adsorbent for fast adsorption of CR and MG. The adsorption kinetics studies showed that the adsorption mechanism of CR and MG followed the pseudo-second model and the adsorption process fitted well to Langmuir isotherm equation. Thermodynamic experiments have shown that the adsorption process is spontaneous and endothermic. The maximum adsorption capacities of CR and MG were 176.06 and 448.43 mg/g, respectively. Under the optimum conditions, BHP-MOFs were successfully used as magnetic adsorbents for the removal of CR and MG in environmental water and fruit juices, with removal efficiency ranged from 97.09% to 76.00%. The reusability of the BHP-MOFs was repeated with seven cycles and removal efficiency remained at 63.01% and 82.20% for CR and MG, respectively. It is proved that BHP-MOFs composite has excellent adsorption capacity for dyes and has a wide application prospect in practical applications.

Electrochemical Sensing of H2O2 by Employing a Flexible Fe3O4/Graphene/Carbon Cloth as Working Electrode

We report the synthesis of Fe3O4/graphene (Fe3O4/Gr) nanocomposite for highly selective and highly sensitive peroxide sensor application. The nanocomposites were produced by a modified co-precipitation method. Further, structural, chemical, and morphological characterization of the Fe3O4/Gr was investigated by standard characterization techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and high-resolution TEM (HRTEM), Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). The average crystal size of Fe3O4 nanoparticles was calculated as 14.5 nm. Moreover, nanocomposite (Fe3O4/Gr) was employed to fabricate the flexible electrode using polymeric carbon fiber cloth or carbon cloth (pCFC or CC) as support. The electrochemical performance of as-fabricated Fe3O4/Gr/CC was evaluated toward H2O2 with excellent electrocatalytic activity. It was found that Fe3O4/Gr/CC-based electrodes show a good linear range, high sensitivity, and a low detection limit for H2O2 detection. The linear range for the optimized sensor was found to be in the range of 10-110 μM and limit of detection was calculated as 4.79 μM with a sensitivity of 0.037 µA μM-1 cm-2. The cost-effective materials used in this work as compared to noble metals provide satisfactory results. As well as showing high stability, the proposed biosensor is also highly reproducible.

Preparation of RGO/Fe3O4 Nanocomposites as a Microwave Absorbing Material

The hydrophobic nanocomposites of reduced graphene oxide (RGO) and Fe3O4 (RGO/Fe3O4) were prepared by a one-pot process through co-precipitation under alkaline conditions. The microwave absorption performance of the RGO/Fe3O4 nanocomposites was analyzed according to their electromagnetic parameters. The results showed that the RGO/Fe3O4 nanocomposites displayed better absorbing performance than the pristine Fe3O4 nanoparticles, owing to the synergistic effect of Fe3O4 and RGO. The maximum reflection loss (RL) of the RGO/Fe3O4 nanocomposites with a thickness of 2 mm reached −45.7 dB at 13.3 GHz, and the bandwidth (RL < −10 dB) ranged from 11.5 to 16.5 GHz. However, the maximum RL of the Fe3O4 nanoparticles with a thickness of 5 mm only reached −5.3 dB at 5.7 GHz. The RGO/Fe3O4 nanocomposites have a great potential application in high-performance electromagnetic microwave absorbing.

Directional electromagnetic interference shielding of asymmetric structure based on dual-needle 3D printing

Some special electronic equipment not only need to avoid the interference of external electromagnetic waves (EMWs), but also need to transmit effective signals. Therefore, the development of directional electromagnetic interference (EMI) shielding materials has a great prospect. The asymmetric structure, consisting of the porous magentic rGF (reduced graphene oxide and Fe3O4) layer and the dense electrical conductivity rGM (reduced graphene oxide and MXene) layer, was constructed by dual-needle 3D printing technology. After encapsulation and curing with polydimethylsiloxane (PDMS), the rGF/rGM/PDMS composites were prepared. When the ratio of rGF and rGM layers is 6:4, the SE values of rGF-6/rGM-4/PDMS composites are 38.75 dB and 30.79 dB respectively when EMWs are incident on the rGF layer and rGM layer respectively, and the ΔSE of which is about 8 dB. The results showed that the asymmetric structure composed of porous magnetic layer and dense deeply electric conductive layer could generate a special process of "weak reflection-absorption-strong reflection-reabsorption" for incident EMW. At the same time, the simulation results of the waveguide method validated the experimental results, and further explained the directional EMI shielding mechanism of asymmetric structure. For the first time, this work designs an asymmetric structure based on the double needle 3D printing technology, which provides useful inspiration for the structural design and potential application of directional EMI shielding materials.

Fabrication of 3D macroporous Fe3O4-GO-Ni through a 'nano-reinforced concrete' method in the application of flexible supercapacitors.

Aqueous flexible supercapacitors have promising potential in the application of wearable electronics but are limited by their low energy densities. Typically, thin nanostructured active materials are deposited on current collectors to achieve high specific capacitances based on active materials, yet the capacitance of total electrodes is sacrificed. The fabrication of 3D macroporous current collectors is a pioneering solution to retain the high specific capacitances of both active materials and electrodes, achieving supercapacitors with high energy density. In this work, through a 'nano-reinforced concrete' method, Fe3O4-GO-Ni with a 3D macroporous structure is synthesized on the surface of cotton threads. In the synthesis process, Ni, hollow Fe3O4 microspheres and graphene oxide (GO) function as the adhesive, fillers, and reinforced and structural materials, respectively. The resultant Fe3O4-GO-Ni@cotton exhibits ultrahigh specific capacitances of 4.71 and 1.85 F cm-2 as positive and negative electrodes, respectively. The electrodes with 3D macroporous structures have good compatibility with the volume change of active materials during the charge-discharge process, leading to excellent long-cycle performance up to 10 000 charge-discharge cycles. To demonstrate the potential of practical applications, a flexible symmetric supercapacitor is fabricated using Fe3O4-GO-Ni@cotton electrodes and shows an energy density of 19.64 mW h cm-3.

Decoration of graphene oxide nanosheets with carboxymethylcellulose hydrogel, silk fibroin and magnetic nanoparticles for biomedical and hyperthermia applications.

In this study, an efficient nanobiocomposite based on graphene oxide (GO), carboxymethylcellulose (CMC) hydrogel, silk fibroin (SF), and Fe3O4 nanoparticles was synthesized. For this purpose and in order to provide a suitable scaffold for the nanobiocomposite, GO was functionalized with a CMC hydrogel via covalent bonding. In the next step, SF was added to the synthesized structure to increase biocompatibility and biodegradability. Fe3O4 was added into the structure by an in situ process and the GO-CMC hydrogel/SF/Fe3O4 nanobiocomposite was synthesized. The synthesized structure was evaluated in terms of toxicity and hemocompatibility and finally, it was used in the hyperthermia technique. This nanocomposite did not destroy healthy HEK293T cells after 48 h and 72 h, while it did annihilate BT549 cancer cells. The GO-CMC hydrogel/SF/Fe3O4 nanobiocomposite has EC50 values of 0.01466 and 0.1415 against HEK293T normal cells and BT549 cancer cells, respectively (after 72 h). The nanocomposite has good potential in hyperthermia applications and at a concentration and a frequency of 1 mg mL-1 and 400 kHz it has a SAR of 67.7 W g-1.

Simultaneous precipitation and discharge plasma processing for one-step synthesis of α-Fe2O3-Fe3O4/graphene visible light magnetically separable photocatalysts.

A novel facile combination of precipitation and plasma discharge reaction is successfully employed for one-step synthesis of an α-Fe2O3-Fe3O4 graphene nanocomposite (GFs). The co-existence and anchoring of hematite (α-Fe2O3) and magnetite (Fe3O4) nanoparticles onto a graphene sheet in the as synthesized GFs were verified by results of XRD, Raman, SEM, TEM, and XPS. HRTEM characterization was used for confirming the bonding between α-Fe2O3/Fe3O4 nanoparticles and the graphene sheet. Consequently, GFs shows superior photodegrading performance towards methylene blue (MB), compared to individual α-Fe2O3/Fe3O4 nanoparticles, as a result of band gap narrowing and the electron-hole pair recombination rate reducing. Moreover, GFs allows a good possibility of separating and recycling under an external-magnetic field, suggesting potential in visible-light-promoted photocatalytic applications.

Comparative Evaluation of Different Surface Coatings of Fe3O4-Based Magnetic Nano Sorbent for Applications in the Nucleic Acids Extraction.

Nucleic acid extraction and purification are crucial steps in sample preparation for multiple diagnostic procedures. Routine methodologies of DNA isolation require benchtop equipment (e.g., centrifuges) and labor-intensive steps. Magnetic nanoparticles (MNPs) as solid-phase sorbents could simplify this procedure. A wide range of surface coatings employs various molecular interactions between dsDNA and magnetic nano-sorbents. However, a reliable, comparative evaluation of their performance is complex. In this work, selected Fe3O4 modifications, i.e., polyethyleneimine, gold, silica, and graphene derivatives, were comprehensively evaluated for applications in dsDNA extraction. A family of single batch nanoparticles was compared in terms of morphology (STEM), composition (ICP-MS/MS and elemental analysis), surface coating (UV-Vis, TGA, FTIR), and MNP charge (ζ-potential). ICP-MS/MS was also used to unify MNPs concentration allowing a reliable assessment of individual coatings on DNA extraction. Moreover, studies on adsorption medium (monovalent vs. divalent ions) and extraction buffer composition were carried out. As a result, essential relationships between nanoparticle coatings and DNA adsorption efficiencies have been noticed. Fe3O4@PEI MNPs turned out to be the most efficient nano sorbents. The optimized composition of the extraction buffer (medium containing 0.1 mM EDTA) helped avoid problems with Fe3+ stripping, which improved the validity of the spectroscopic determination of DNA recovery.

Comparative efficiency of polycyclic aromatic hydrocarbon removal by novel graphene oxide composites prepared from conventional and green synthesis

New materials have been developed based on the pillars of green chemistry; however, few studies compare the potential of these materials with that of conventional materials. In this study, two composites based on graphene oxide and magnetic chitosan were synthesized, one by the green route (G-mCS/GO) and the other by the conventional route (C-mCS/GO), using proanthocyanidin (PAS) and glutaraldehyde as crosslinking agents, respectively. Then, they were applied as adsorbents in the removal of polycyclic aromatic hydrocarbons (PAHs) from synthetic wastewater to compare their performance. Through XRD analysis, the crystallographic properties were obtained, FT-IR analyses indicated the presence of functional groups associated with graphene oxide, chitosan and Fe3O4 particles, and the magnetization curves indicated greater saturation magnetization for G-mCS/GO. Adsorption assays were performed at 298 K for 30 min at pH 6.5, an adsorbent dosage of 0.1 mg mL−1 and an initial PAH concentration of 0.01 mmol. L−1 showed a greater adsorptive capacity of G-mCS/GO for naphthalene (0.093 mmol g−1) and anthracene (0.089 mmol g−1), with removal efficiencies of 93.55% and 89.25%, respectively. On the other hand, C-mCS/GO showed a better removal efficiency for fluoranthene (0.076 mmol g−1), 76.07%. The results obtained through the molecular simulation indicated that naphthalene molecules have greater stability than anthracene and fluoranthene, which contributes to increasing the hydrophobic and π-π interactions between the PAH molecules and the adsorbent surface, thus inducing an increase in the adsorptive capacity. The results of this study indicate that G-mCS/GO is a potential and sustainable adsorbent for PAH removal from wastewater.