Superparamagnetic Carbon Research Articles

A circular approach for the treatment of aqueous metal effluent and biomass to generate superparamagnetic nanometal carbon hybrid and hydrogen-rich gas mixture

In this study, simulated water effluent of transition metals (Ni, Zn, Fe, and Cu) and pine needles were integrated and treated hydrothermally for the generation of hydrogen and superparamagnetic carbon hybrid of metal/metal oxides of nano-size in a single-step. The temperature plays a significant role and decides the product yield and the same was varied (300-600 °C) to optimize the product yield. The highest yield of hydrogen was obtained with nickel metal effluent, 17.2 mmol. gram−1 of pine needles at 600 °C followed by other metals i.e., Fe(11.3 mmol.gram−1), Cu (10.64 mmol.gram−1), and Zn (8.86 mmol.gram−1) and greater than 99 % of the heavy metals (HMs) has been recovered from effluents (Ni, Zn, Fe, and Cu) in the form of nanometal carbon hybrid. The synthesized nanometal carbon hybrids were analyzed with the help of X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), which shows that the metals present in the effluent get transferred to the lignocellulosic matrix of biomass during the supercritical water gasification (SCWG) that eventually gets reduced to pure metal (M(o)) from metal oxide (M(+n)). Metal oxide reduction results in the release of active oxygen, which promote the decomposition of the organics of biomass. Furthermore, the in-situ generated pure metal (M(o)) catalyzes the steam reforming and water gas shift reaction (WGS). Moreover, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM) indicate that synthesized nanometal carbon nanometal hybrid was quasi-spherical or cubical has a size less than <30 nm and are superparamagnetic material.

Doxorubicin delivery performance of superparamagnetic carbon multi-core shell nanoparticles: pH dependence, stability and kinetic insight

In the past decade, magnetic nanoparticles (MNPs) have been among the most attractive nanomaterials used in different fields, such as environmental and biomedical applications. The possibility of designing nanoparticles with different functionalities allows for advancing the biomedical applications of these materials. Additionally, the magnetic characteristics of the nanoparticles enable the use of magnetic fields to drive the nanoparticles to the desired sites of delivery. In this context, the development of new MNPs in new approaches for drug delivery systems (DDSs) for cancer treatment has increased. However, the synthesis of nanoparticles with high colloidal stability triggered drug delivery, and good biocompatibility remains a challenge. Herein, multi-core shell MNPs functionalized with Pluronic ® F-127 were prepared and thoroughly characterized as drug carriers for doxorubicin delivery. The functionalized nanoparticles have an average size of 17.71 ± 4.2 nm, high water colloidal stability, and superparamagnetic behavior. In addition, the nanoparticles were able to load 936 μg of DOX per mg of functionalized nanomaterial. Drug release studies at different pH values evidenced a pH-triggered DOX release effect. An increase of 62% in cumulative drug release was observed at pH simulating tumor endosome/lysosome microenvironments (pH 4.5) compared to physiological conditions (pH 7.4). In addition, an innovative dynamic drug delivery study was performed as a function of pH. The results from this test confirmed the pH-induced doxorubicin release capability of carbon multi-core shell MNPs. The validity of traditional kinetic models to fit dynamic pH-dependent drug release was also studied for predictive purposes.

Distribution behavior of superparamagnetic carbon nanotubes in an aqueous system.

This study investigates the distribution behavior of superparamagnetic multiwalled carbon nanotubes (SPM-MWCNTs) in an aqueous system containing Lake Tai sediment. Specifically, the effects of dissolved organic matter (DOM) and sediment on SPM-MWCNTs under various conditions and the interaction forms between them were evaluated through a modified mathematical model and characterization. The results showed that DOM can stabilize SPM-MWCNTs by providing sterically and electrostatically stable surfaces, even under high sodium concentrations. The fitting accuracy of the Freundlich adsorption isotherm is higher than that of the Langmuir adsorption isotherm. Therefore, the adsorption of SPM-MWCNT on the sediment should proceed through a multiple, complex and heterogeneous adsorption mechanism. Characterization analyses indicated that DOM may serve as a bridge for the inorganic adsorption between SPM-MWCNTs and sediment. This study is the first to investigate the distribution behavior of magnetite coated carbon nanotubes (CNTs), which simplified the separation and quantification considerably. The findings of this study will serve as a valuable reference for future studies of magnetic CNTs.

Enhanced Photodegradation of Organic Pollutants by Carbon Quantum Dot (CQD) Deposited Fe3O4@mTiO2 Nano-Pom-Pom Balls

Highly water dispersible, superparamagnetic carbon quantum dot (CQD) deposited Fe3O4@mTiO2 pom-pom balls have been prepared by a simple hydrothermal method. The effective deposition of carbon dots expands the light absorption of mTiO2 from the UV to visible region. The results of photocurrent measurement reveal that an optimum deposition of C-dot at 20 wt % significantly increases the photocurrent density. High surface area and extended conjugation of carbon dots enhance the adsorption of organic pollutants. The active species generated in the photocatalytic system were also detected through trapping of radicals and holes in the presence of various scavengers. In a comparison with a conventional photocatalyst such as Degussa P25, the developed heterojunction shows much higher degradation efficiency for ciprofloxacin, methylene blue, quinalphos, and 4-nitrophenol under visible light. The light upconversion properties of uniformly deposited carbon quantum dots could be a reason for higher visible light cata...

Ethylenediamine-functionalized superparamagnetic carbon nanotubes for magnetic molecularly imprinted polymer matrix solid-phase dispersion extraction of 12 fluoroquinolones in river water

A novel fluoroquinolone molecularly imprinted polymer (MIP) on the surface of ethylenediamine-functionalized magnetic carbon nanotubes (EDA@Mag-CNTs–MIP) was synthesised.

Synthesis of superparamagnetic carbon nanotubes immobilized Pt and Pd pincer complexes: highly active and selective catalysts towards cyclohexane oxidation with dioxygen

Single-walled carbon nanotubes (SWNTs) with Ni/Co have been prepared using an arc discharge technique and Ni/Co-carbon composite rods in an inert atmosphere and were surface modified using 3-aminophenyl trimethoxysilane. These NH2-functionalized magnetic carbon nanotubes have been used as a novel support for Pd((II)) and Pt((II)) pincer complexes immobilized as magnetic nano-catalysts. The morphology of the support and the catalysts have been characterized by IR, EPR, SEM, TGA, TEM, XRD, AAS and EDS analysis. These magnetic nano-catalysts have been tested on the industrially important cyclohexane (Cy-hx) oxidation with O2 and significantly high TONs of 1678 to 1946 were achieved under solvent free and relatively mild conditions. The SWNTs/Pd catalyst provided the best conversion, 22.7%, but the SWNTs/Pt system also provided a good conversion of 20.7%.

Silver recovery using electrochemically active magnetite coated carbon particles

The electrochemical recovery of silver by employing recyclable superparamagnetic carbon materials (Cmag) is reported. The proposed strategy explores the adsorption properties and the large surface area of carbon, in conjunction with the superparamagnetic properties of magnetite nanoparticles, in order to collect Ag+ ions from the solution and to promove their rapid confinement at the working electrode surface, using an external magnet. Efficient electrodeposition can be performed in this way, facilitated by the preconcentration effect at the electrode. The adsorption process at the magnetic carbon particles proceeds according to the Langmuir model, exhibiting an adsorption capability of 61.5mg of silver per gram of Cmag. As a proof of concept, an automated system was specially designed for performing successive batch cycles, encompassing the capture, transport, confinement, electrodepositon of silver, and recycling of the magnetite coated carbon particles from the electrode. The recovery process was successfully demonstrated in this work, by processing discarded X-ray photographic films.

Cellulose-derived superparamagnetic carbonaceous solid acid catalyst for cellulose hydrolysis in an ionic liquid or aqueous reaction system

A cellulose-derived carbonaceous solid acid catalyst that has superparamagnetism was synthesized by incomplete hydrothermal carbonization of cellulose followed by Fe3O4 grafting and –SO3H group functionalization. The as-prepared superparamagnetic carbon catalyst contained –SO3H, –COOH, and phenolic –OH groups and exhibited good catalytic activity for the hydrolysis of cellulose in either an ionic liquid phase or aqueous phase. A total reducing sugar (TRS) yield of 68.9% was obtained with ionic liquid 1-butyl-3-methyl imidazolium chloride ([BMIM][Cl]) at 130 °C for a 3 h reaction time. A TRS yield of 51% was obtained with water at 180 °C for a 9 h reaction time. The catalyst was applied to rice straw for which a TRS yield of 35.5%, based on the total mass of loaded rice straw, was obtained in [BMIM][Cl] at 150 °C in 2 h. The superparamagnetic carbonaceous solid acid catalyst was easily separated from the reaction products with an external magnetic field and used for subsequent recycling experiments. The activity of the recycled catalyst decreased with a recycle number that is attributed to some loss of the catalyst and adsorption of humin products on the active catalyst sites.

Efficient removal of heavy metal ions by thiol-functionalized superparamagnetic carbon nanotubes

Thiol-functionalized multiwall carbon nanotube/magnetite nanocomposites (CNTs/Fe3O4) were synthesized, and were investigated by power X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectrometer, Fourier transform infrared spectroscopy, thermogravimetric analyses, BET analysis and physical properties measurement system. The results showed that the 3-mercaptopropyltriethoxysilane (MPTS) was successfully grafted on the surface of CNTs/Fe3O4 nanocomposites. The as-synthesized thiol-functionalized CNTs/Fe3O4 (MPTS-CNTs/Fe3O4) nanocomposites exhibited superparamagnetic property and higher specific surface area than that of CNTs/Fe3O4 nanocomposites at room temperature. The adsorption properties of Hg2+ and Pb2+ as a function of contact time, pH value and initial metal concentration were characterized by an inductively coupled plasma optical emission spectroscopy (ICP-OES). The pseudo-first-order kinetic equation could better than that of pseudo-second-order kinetic equation to describe the adsorption kinetics of the before and after thiol-functionalized nanocopmposites. The removal efficiency of CNTs/Fe3O4 nanocomposites and MPTS-CNTs/Fe3O4 nanocomposites was highly pH dependent and the optimal pH value for adsorption was 6.5. The adsorption isotherms of Hg2+ and Pb2+ by MPTS-CNTs/Fe3O4 nanocomposites matched well with the Langmuir model with the maximum adsorption capacities of 65.52 and 65.40mg/g, respectively.

Superparamagnetic Carbon Electrodes: A Versatile Approach for Performing Magnetic Coupled Electrochemical Analysis of Mercury Ions

AbstractMercury ions can be captured with superparamagnetic carbon powder substrates and transported to the electrode surface using an external miniature magnet. The magnetic carbon substrate is electronically conducting, and more than promoting efficient preconcentration of the element at the electrode, it increases the electrochemical surface area by forming an extended 3D structure in the presence of a magnetic field. The external magnet allows to perform direct electrochemical analysis, leading to a strong enhancement of the analytical signals for the reduction of the Hg(II) ions.