Fe3O4@C Core-Shell Carbon Hybrid Materials as Magnetically Separable Adsorbents for the Removal of Dibenzothiophene in Fuels

Ultrasound-assisted adsorption approach for desulfurization of n-heptane using nitrogen-doped magnetic carbon dot nanocomposite

Desulfurization is an important process that not only affects the quality and performances of fuels but also is of great importance from environmental aspects. In this research, nitrogen-doped magnetic carbon dots nanocomposite was synthesized and characterized, and it's potential in adsorptive removal of thiophenes (i.e., thiophene, benzothiophene, and dibenzothiophene) from n-heptane (i.e., as model fuel) was investigated. After optimization of adsorption process, the removal efficiency was obtained above 95% for all of studied thiophenes. Besides that, it was concluded that using ultrasound during the adsorption process could enhance the maximum adsorption capacity. Langmuir model was able to appropriately describe the adsorption isotherm data, where the maximum equilibrium adsorption capacities for thiophene, benzothiophene and dibenzothiophene were obtained as 90.22, 96.51 and 100.38 mgg-1, respectively. The analysis of kinetic data also revealed that all thiophenes were being adsorbed following Pseudo-second-order model. To regenerate the adsorbent, the desorption process was also investigated using different solvents under different conditions, methanol was found as effective solvent for regeneration. The proposed adsorbent was used successfully for the removal of pollutants in a gasoline sample.

Designing novel perlite-Fe3O4@SiO2@8-HQ-5-SA as a promising magnetic nanoadsorbent for competitive adsorption of multicomponent VOCs

Volatile organic compounds (VOCs), which emerge as multicomponent pollutants through many industrial processes, pose a serious threat to human health and the eco-environment due to their volatility, toxicity and dispersion. Hence, the study of competitive adsorption of multicomponent VOCs is of practical and scientific importance. Herein, the perlite-supported Fe3O4@SiO2@8-hydroxyquinoline-5-sulfonic acid (perlite-Fe3O4@SiO2@8-HQ-5-SA) was designed as a novel magnetic nanoadsorbent by a simple strategy and employed for the competitive adsorption of multicomponent toluene, ethylbenzene and xylene in the vapor-phase targeted as VOCs. The successfully prepared perlite-Fe3O4@SiO2@8-HQ-5-SA was characterized by means of SEM, EDX, FT-IR, VSM and BET analyses. Adsorption capacities of 558 mg/g, 680 mg/g and 716 mg/g were achieved for single component toluene, ethylbenzene and xylene, respectively. It was concluded that the adsorption capacities for both binary and ternary components were significantly decreased compared to single component adsorption. The competitive adsorption capacity order of the binary and ternary component VOCs was xylene > ethylbenzene > toluene due to their competitive dominance. The rate-limiting kinetic analysis indicated that the adsorption rates were determined by both the film diffusion and intraparticle diffusion. The analysis of the error metrics demonstrated that the three-parameter isotherm models better described the adsorption data compared to the two-parameter models. In particular, the Toth model provided the closest fit to the experimental equilibrium data. The thermodynamic analysis indicated the spontaneous nature and probability (ΔG° <0), exothermic (ΔH° <0), physical (ΔH° <20 kJ/mol) and a declination in the degree of randomness (ΔS° <0) of the adsorption processes. The reuse efficiency of perlite-Fe3O4@SiO2@8-HQ-5-SA for toluene, ethylbenzene and xylene decreased to only by 88.91%, 88.07% and 87.16% after five recycles. The perlite-Fe3O4@SiO2@8-HQ-5-SA has a significant adsorptive potential compared to other adsorbents reported in the literature, thus it could be recommended as a promising nanoadsorbent for VOCs in industrial processes.

Fabrication and characterization of 3,4-diaminobenzophenone-functionalized magnetic nanoadsorbent with enhanced VOC adsorption and desorption capacity

The present study, for the first time, utilized 3,4-diaminobenzophenone (DABP)-functionalized Fe₃O₄/AC@SiO₂ (Fe₃O₄/AC@SiO₂@DABP) magnetic nanoparticles (MNPs) synthesized as a nanoadsorbent for enhancing adsorption and desorption capacity of gaseous benzene and toluene as volatile organic compounds (VOCs). The Fe₃O₄/AC@SiO₂@DABP MNPs used in adsorption and desorption of benzene and toluene were synthesized by the co-precipitation and sol-gel methods. The synthesized MNPs were characterized by SEM, FTIR, TGA/DTA, and BET surface area analysis. Moreover, the optimization of the process parameters, namely contact time, initial VOC concentration, and temperature, was performed by applying response surface methodology (RSM). Adsorption results demonstrated that the Fe₃O₄/AC@SiO₂@DABP MNPs had excellent adsorption capacity. The maximum adsorption capacities for benzene and toluene were found as 530.99 and 666.00 mg/g, respectively, under optimum process parameters (contact time 55.47 min, initial benzene concentration 17.57 ppm, and temperature 29.09 °C; and contact time 57.54 min, initial toluene concentration 17.83 ppm, and temperature 27.93 °C for benzene and toluene, respectively). In addition to the distinctive adsorptive behavior, the Fe₃O₄/AC@SiO₂@DABP MNPs exhibited a high reproducibility adsorption and desorption capacity. After the fifth adsorption and desorption cycles, the Fe₃O₄/AC@SiO₂@DABP MNPs retained 94.4% and 95.4% of its initial adsorption capacity for benzene and toluene, respectively. Kinetic and isotherm findings suggested that the adsorption mechanisms of benzene and toluene on the Fe₃O₄/AC@SiO₂@DABP MNPs were physical processes. The results indicated that the successfully synthesized Fe₃O₄/AC@SiO₂@DABP MNPs can be applied as an attractive, highly effective, reusable, and cost-effective adsorbent for the adsorption of VOC pollutants.Graphical abstract.

Surface engineering of magnetic iron oxide nanoparticles by polymer grafting: synthesis progress and biomedical applications

Magnetic iron oxide nanoparticles (IONPs) have wide applications in magnetic resonance imaging (MRI), biomedicine, drug delivery, hyperthermia therapy, catalysis, magnetic separation, and others. However, these applications are usually limited by irreversible agglomeration of IONPs in aqueous media because of their dipole-dipole interactions, and their poor stability. A protecting polymeric shell provides IONPs with not only enhanced long-term stability, but also the functionality of polymer shells. Therefore, polymer-grafted IONPs have recently attracted much attention of scientists. In this tutorial review, we will present the current strategies for grafting polymers onto the surface of IONPs, basically including "grafting from" and "grafting to" methods. Available functional groups and chemical reactions, which could be employed to bind polymers onto the IONP surface, are comprehensively summarized. Moreover, the applications of polymer-grafted IONPs will be briefly discussed. Finally, future challenges and perspectives in the synthesis and application of polymer-grafted IONPs will also be discussed.

Fast and Controllable Synthesis of Core-Shell Fe3O4-C Nanoparticles by Aerosol CVD

A method for simple and fast (30-60 s) synthesis of spherical "Fe₃O₄ core-carbon shell" structures by atmospheric pressure aerosol pyrolysis of benzoic acid in dimethylformamide solutions containing dispersed Fe₃O₄ nanoparticles is described. It has been experimentally shown that it is possible to control both the size of the core-shell particles and the size of Fe₃O₄ grains and their amount in the particle core by the variation of benzoic acid concentration in solution and using pre-stabilized by mannitol iron oxide nanoparticles. It has been found that particles with an average size of 250-350 nm are formed at the concentration of benzoic acid in the range 0.5-1 mol/L. At a concentration of about 1 mol/L, preliminary stabilization of iron oxide nanoparticles by mannitol with a size of about 180 nm is performed.

Investigation of high-performance adsorption for benzene and toluene vapors by calix[4]arene based organosilica (CBOS)

Calix[4]arene based organosilica (CBOS) was successfully prepared, characterized, and used for the adsorption of benzene and toluene vapors for the first time. The benzene and toluene vapor uptake of CBOS was determined to be 606 and 672 mg g⁻¹, respectively.

High extent mass recovery of alginate hydrogel beads network based on immobilized bio-sourced porous carbon@Fe3O4-NPs for organic pollutants uptake

This work goes inside the understanding of organic pollutants adsorption mechanism over network alginate hydrogel beads based on immobilized bio-sourced PC@Fe₃O₄-NPs (PC@Fe₃O₄-NPs@Alginate) and highlights its high extent mass recovery in aqueous media. The samples were successfully synthesized, we previously developed porous carbon (PC), which, was used to elaborate PC@Fe₃O₄-NPs via simple in situ coprecipitation (PC@ Fe₃O₄-NPs), which was encapsulated by alginate-Ca²⁺ via the blend crosslinking method. The structural, textural, chemical and morphological proprieties of as prepared materials were studied by XRD, FTIR, Raman spectroscopy, nitrogen adsorption-desorption, XPS, SEM and TEM. The adsorption kinetic and isotherm data were well fitted to the pseudo-second-order and Langmuir models. Magnetic particles exhibited an excellent ability to adsorb methylene blue (MB) from aqueous solutions with maximum MB adsorption capacity of 180.42 mg g^-1 (PC@Fe₃O₄ NPs powder) and 49.66 mg g^-1 (beads based PC@Fe₃O₄-NPs@Alginate). Response surface methodology was used to optimize the removal efficiency of MB from aqueous solution and optimum parameters were determined. Magnetic beads based PC showed good magnetic propriety, long-term stability, regeneration capabilities and high extent mass recovery.

Enhancement of Photocatalytic Activity under Visible Light Irradiation via the AgI@TCNQ Core-Shell Structure

In this paper, a AgI@TCNQ photocatalyst with a core-shell structure was reported. A two-dimensional TCNQ (7,7,8,8-Tetracyanoquinodimethane) nanosheet, with a π-π conjugate structure, was used as a shell layer to realize the flexible coating on the surface of AgI nanoparticles. These special core-shell structure composites solve the key problems of the small interface of the bulk composites and the lesser charge transfer paths, which could accelerate the migration of photogenerated carriers. Thus, the AgI@TCNQ photocatalysts showed the better photodegradation performance for the methylene blue (MB) solution, and the degradation rate of AgI@TCNQ (1 wt.%) composite was 1.8 times than AgI under irradiation. The reactive species trapping experiments demonstrated that ·O2-, h+, and ·OH all participated in the MB degradation process. The photocatalytic mechanism of AgI@TCNQ composites could be rationally explained by considering the Z-scheme structure, resulting in a higher redox potential and more efficient separation of charge carriers. At the same time, the unique core-shell structure provides a larger contact area, expands the charge transport channel, and increases the surface active sites, which are beneficial for improving photocatalytic performance.