Magnetic Nanocatalyst Research Articles

Optimization of culture conditions of Scenedesmus sp. algae and catalytic performance of a NiFe2O4@SiO2/MgO magnetic nano-catalyst for biodiesel production.

This study aims to optimize the lipid content of Scenedesmus sp. for high-yield biodiesel production. Three factors affecting the culture conditions, namely salinity, nitrogen concentration, and light intensity, were selected and their effects on the maximum lipid content were investigated using the Box Behnken design. The results showed that the maximum lipid content (32.7% of algal dry weight) was obtained in the algal samples cultured under the optimized conditions. A core-shell magnetic nano-catalyst, NiFe2O4@SiO2/MgO, was synthesized and used to produce biodiesel via the transesterification reaction. The nano-catalyst was characterized by field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray powder diffraction analysis (XRD), vibrating sample magnetometry (VSM), elemental mapping techniques, transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR). Using the Box Behnken design and keeping the temperature constant, the molar ratio of methanol to oil, the amount of catalyst, and the time were optimized to achieve the maximum yield of biodiesel. The maximum yield of biodiesel was 95.3% under the optimal conditions.

Efficient biodiesel production from recycled cooking oil using a NaOH/CoFe2O4 magnetic nano-catalyst: synthesis, characterization, and process enhancement for sustainability

This research introduces an environmentally sustainable approach to biodiesel production, utilizing waste cooking oil (WCO) as a renewable feedstock. The focal point of this study is the synthesis and characterization of NaOH/CoFe2O4 magnetic nanoparticles, employed as an efficient catalyst for the transesterification reaction between WCO and methanol. Comprehensive analysis, including X-ray diffraction, Fourier transform infrared spectroscopy, scanning electronic microscopy, magnetometry, temperature-programmed carbon dioxide and ammonia desorption, and X-ray photoelectron spectroscopy reveals nanoparticles with remarkable catalytic properties. The transesterification process catalyzed by NaOH/CoFe2O4 yields biodiesel at an impressive rate of 98.71%, complying with ASTM standards. Kinetic and thermodynamic evaluations elucidate reaction mechanisms, and density functional theory (DFT) calculations provide insights into the catalytic process. The magnetic catalyst's reusability enhances sustainability, making it a promising solution for large-scale biodiesel production, and lays the foundation for future catalyst optimization.

Expression of concern: Highly porous copper-supported magnetic nanocatalysts: made of volcanic pumice textured by cellulose and applied for the reduction of nitrobenzene derivatives.

Expression of concern for 'Highly porous copper-supported magnetic nanocatalysts: made of volcanic pumice textured by cellulose and applied for the reduction of nitrobenzene derivatives' by Reza Taheri-Ledari et al., RSC Adv., 2021, 11, 25284-25295, https://doi.org/10.1039/D1RA03538J.

Fe3O4@SiO2@SBA-3@CPTMS@Arg-Cu: preparation, characterization, and catalytic performance in the conversion of nitriles to amides and the synthesis of 5-substituted 1H-tetrazoles.

A novel, efficient, and recyclable mesoporous Fe3O4@SiO2@SBA-3@CPTMS@Arg-Cu nanocatalyst was synthesized by grafting l-arginine (with the ability to coordinate with Cu) onto a mixed phase of a magnetic mesoporous SBA-3 support. The catalyst was characterized using several techniques, including Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), X-ray diffraction (XRD) analysis, N2 adsorption-desorption analysis, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray (EDX) analysis, and atomic absorption spectroscopy (AAS). The resulting solid material possessed a surface area of 145 m2 g-1 and a total pore volume of 34 cm3 g-1. The prepared mesoporous material was studied as a practical, recyclable, and chemoselective catalyst in some organic functional group transformations such as the conversion of nitriles to amides and synthesis of 5-substituted 1H-tetrazoles. This novel magnetic nanocatalyst proved to be effective and provided the products in high to excellent yields under green solvent conditions. Meanwhile, the as-prepared Fe3O4@SiO2@SBA-3@CPTMS@Arg-Cu demonstrated excellent reusability and stability under reaction conditions, and its catalytic activity shown only a slight decrease after seven consecutive runs. Therefore, the as-synthesized magnetic Fe3O4@SiO2@SBA-3@CPTMS@Arg-Cu has broad prospects for practical applications, and offers various benefits such as simplicity, nontoxicity, low cost, simple work-up, and an environmentally benign nature.

Fe3O4@SiO2 core/shell functionalized by gallic acid: a novel, robust, and water-compatible heterogeneous magnetic nanocatalyst for environmentally friendly synthesis of acridine-1,8-diones.

In this study, we conveniently prepared a novel robust heterogeneous magnetic nanocatalyst using a Fe3O4@SiO2 core/shell stabilized by gallic acid. The catalyst was completely characterized by various physicochemical techniques, including infrared spectroscopy (FT-IR), X-ray diffraction (XRD), dynamic light scattering (DLS), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis (TGA), potentiometric titration, energy dispersive X-ray microanalysis (EDX), vibrating sample magnetometer (VSM), zeta potential analysis, and BET. The potential ability of the newly developed sulfonated nanocatalyst was then exploited in the multicomponent synthesis of acridine-1,8-dione derivatives by considering the green chemistry matrix and under mild conditions. Various aldehydes and amines were smoothly reacted with dimedone, affording the desired products in good to excellent yields. The introduction of sulfonic groups using gallic acid allowed the development of a water-compatible and highly recyclable catalytic system for reactions in an aqueous environment. The prepared catalyst can be readily magnetically separated and reused eight times without significant loss of activity. High synthetic efficiency, using a recyclable and eco-sustainable catalyst under mild conditions, and easy product isolation are salient features of this catalytic system, which makes this protocol compatible with the demands of green chemistry.

An immobilized Schiff base-Mn complex as a hybrid magnetic nanocatalyst for green synthesis of biologically active [4,3-d]pyrido[1,2-a]pyrimidin-6-ones.

The immobilization of metal ions on inorganic supports has garnered significant attention due to its wide range of applications. These immobilized metal ions serve as catalysts for chemical reactions and as probes for studying biological processes. In this study, we successfully prepared Fe3O4@SiO2@Mn-complex by immobilizing manganese onto the surface of magnetic Fe3O4@SiO2 nanoparticles through a layer-by-layer assembly technique. The structure of these hybrid nanoparticles was characterized by various analytical techniques, including Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM), and inductively coupled plasma-optical emission spectrometry (ICP-OES). Fe3O4@SiO2@Mn-complex was successfully utilized in the synthesis of biologically active 7-aryl[4,3-d]pyrido[1,2-a]pyrimidin-6(7H)-one derivatives in an aqueous medium, providing environmentally friendly conditions. The desired products were manufactured in high yields (81-95%) without the formation of side products. The heterogeneity of the solid nanocatalyst was assessed using a hot filtration test that confirmed minimal manganese leaching during the reaction. This procedure offers numerous advantages, including short reaction times, the use of a green solvent, the ability to reuse the catalyst without a significant decrease in catalytic activity, and easy separation of the catalyst using an external magnet. Furthermore, this approach aligns with environmental compatibility and sustainability standards.

Design, preparation and characterization of magnetic nanoparticles functionalized with chitosan/Schiff base and their use as a reusable nanocatalyst for the green synthesis of 1H-isochromenes under mild conditions.

In this study, a Schiff base complex magnetic nanocatalyst was designed and prepared. The structure of the Fe3O4@CS-SB-CaMgFe2O4 nanocatalyst was characterized using FT-IR spectroscopy, XRD, VSM, FE-SEM, EDX, elemental mapping, BET, and TGA techniques. The synthesis of 1H-isochromene compounds has attracted the attention of chemists due to their biological and medicinal properties. The 1H-isochromene derivatives were synthesized in the presence of the Fe3O4@CS-SB-CaMgFe2O4 nanocatalyst with excellent efficiency and short reaction time as well as according to the rules of green chemistry. This reaction was carried out using Fe3O4@CS-SB-CaMgFe2O4 as a catalyst to develop a simple method with low activation energy at room temperature under optimal conditions. This catalyst provides a promising route for the synthesis of 1H-isochromene multiple times through its recyclability without significant loss of catalytic activity. This nanocatalyst possesses several advantages, including cost-effectiveness, facile separation, environmental friendliness, and recyclability, for the efficient production of 1H-isochromenes. The obtained compounds were further analyzed using spectroscopic techniques, such as melting point, FT-IR, 1H NMR, and 13C NMR analyses, to confirm their structures. The spectra of the synthesized compounds were recorded and analyzed, and a plausible mechanism for their synthesis was proposed. The characterization results and structural elucidation provide valuable insights into the preparation of these compounds.

Novel butane sulfonic acid-functionalized core–shell magnetic nanocatalysts for ultrasound-assisted coumarin synthesis

Novel Fe3O4@C@PrNH@BuSO3H NPs were formulated, fabricated, and used as an efficient nanocatalyst in coumarin synthesis under ultrasound and conventional conditions.

Synthesis of azepane-acridine heterocyclic adducts assisted by the catalytic influence of γ-Fe2O3@TiO2-Vitamin B1 and evaluation of their medicinal potential through in vitro antimicrobial, QSAR, and molecular docking studies

Present work elicits synthesis of novel azepane-acridines, assisted by titania-encapsulated γFe2O3 nanoparticles supported on Vitamin B1 (γFe2O3@TiO2-Vitamin B1) as a new magnetically recyclable heterogeneous nano-catalytic system. The reaction was accomplished using biocompatible PEG-200 (Polyethylene glycol) as the solvent under ultrasonic irradiations. The structure and morphology of synthesized magnetic nano-catalyst was ascertained based on data obtained from powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDAX), Fourier transform infrared (FT-IR), and VSM (Vibrating-sample magnetometer) TGA, DTA and DTG techniques. The characteristic size of the prepared heterogenous nano-catalyst is 34.62 nm. Also, the structures of all the synthesized azepane-acridine heterocyclic scaffolds were corroborated through spectro-analytical data. These new compounds were found to have remarkable biological activity profile against the bacterium S.aureus with IC50 values ranging from 1.41 to 2.75 µg/mL. Further, these in-vitro studies were correlated with statistically significant 2D/3D- QSAR models. The best 2D-QSAR models reveal the positive influence of slogp and Vander Waal Surface area descriptors while the negative influence of the polar surface area and T_2_N_6 descriptors on the bioactivity with ideal values of squared correlation coefficient (r2), cross-validated correlation coefficient (q2) with high values of Fisher ratio (F-test) indicating the model to be statistically relevant. The finest 3D-QSAR models MLR (Multiple Linear Regression method) provide practical information in the characterization and differentiation of compound binding sites. Moreover, molecular docking studies were performed to evaluate the antifungal activity of synthesized scaffolds against the black fungi crystal protein, indicating remarkable bioassay scores. Atom economy, practical feasibility, cost-effectiveness, minimum reaction time, High yields, and an additive-free process are the foremost advantages of the developed methodology.

Expression of Concern: Novel Schiff base Mn(iii) and Co(ii) complexes supported on Co nanoparticles: efficient and recyclable magnetic nanocatalysts for alcohol oxidation

Expression of Concern for ‘Novel Schiff base Mn(iii) and Co(ii) complexes supported on Co nanoparticles: efficient and recyclable magnetic nanocatalysts for alcohol oxidation’ by Hassan Keypour et al., RSC Adv., 2016, 6, 77020–77029, https://doi.org/10.1039/C6RA15967B.

NIR-enhanced multi-mode catalytic activity over Pd nanocrystals sandwiched within magnetic polydopamine hollow spheres

A multi-mode magnetic nanocatalyst shows typical photothermal enhancing catalytic effect under near-infrared (NIR) light irradiation.

Expression of concern: Schiff base Mn(iii) and Co(ii) complexes coated on Co nanoparticles: an efficient and recyclable magnetic nanocatalyst for H2O2 oxidation of sulfides to sulfoxides.

Expression of concern for 'Schiff base Mn(iii) and Co(ii) complexes coated on Co nanoparticles: an efficient and recyclable magnetic nanocatalyst for H2O2 oxidation of sulfides to sulfoxides' by Shokoufeh Ghahri Saremi et al., RSC Adv., 2018, 8, 3889-3898, https://doi.org/10.1039/C7RA11225D.

White-light-emitting diode (LED)-promoted one-pot synthesis of 1,2-dihydropyrimido[1,2-a]benzimidazoles in the presence of a new spiky magnetic nanocatalyst and their anthelmintic studies

Synthesis of benzimidazoles derivatives from an aromatic aldehyde, active methylene compounds, and 2-aminobenzimidazole under white LED irradiation.

A novel magnetic FSM-16 supported ionic liquid/Pd complex as a high performance and recyclable catalyst for the synthesis of pyrano[3,2-c]chromenes.

In this work, Fe3O4@FSM-16/IL-Pd was successfully designed and synthesized via a new procedure of palladium(ii) complex immobilization onto magnetic FSM-16 using an ionic liquid, as a novel heterogeneous nanocatalyst. Multiple techniques were employed to characterize this magnetic nanocatalyst such as Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), Field Emission Scanning Electron Microscopy (FE-SEM), thermogravimetric analysis (TGA), Transmission electron microscopy (TEM), and Vibrating Sample Magnetometry (VSM). After complete characterization of the catalyst, its catalytic activity was used for the synthesis of pyrano[3,2-c]chromene-3-carbonitriles via the reaction of 4-hydroxycoumarin, aldehyde, and malononitrile under solvent-free conditions. Also, it can be recovered and reused several times without a significant decrease in its catalytic activity or palladium leaching.

A Novel Recyclable Magnetic Nano-Catalyst for Fenton-Photodegradation of Methyl Orange and Imidazole Derivatives Catalytic Synthesis.

A magnetite chlorodeoxycellulose/ferroferric oxide (CDC@Fe3O4) heterogeneous photocatalyst was synthesised via treated and modified cotton in two steps. The designed nanocomposites were characterised by FTIR, TGA, XRD, SEM, and VSM analyses. The Fenton-photocatalytic decomposition efficiency of the synthesised magnetic catalyst was evaluated under visible sunlight using Methyl Orange (MO) as a model organic pollutant. The impacts of several degradation parameters, including the light source, catalyst load, irradiation temperature, oxidant dose, and pH of the dye aqueous solution and its corresponding concentration on the Fenton photodegradation performance, were methodically investigated. The (CDC@Fe3O4) heterogeneous catalyst showed a remarkable MO removal rate of 97.9% at 10 min under visible-light irradiation. (CDC@Fe3O4) nanomaterials were also used in a heterogeneous catalytic optimised protocol for a multicomponent reaction procedure to obtain nine tetra-substituted imidazole derivatives. The green protocol afforded imidazole derivatives in 30 min with good yields (91-97%) at room temperature and under ultrasound irradiation. Generally, a synthesised recyclable heterogeneous nano-catalyst is a good example and is suitable for wastewater treatment and organic synthesis.

Development of new magnetic nanocomposite designed by reduced graphene oxide aerogel and HKUST-1, and its catalytic application in the synthesis of polyhydroquinoline and 1,8-dioxo-decahydroacridine derivatives

In this study, new magnetic reduced graphene oxide aerogel/HKUST-1 nanocomposite was designed and synthesized given the transformation of graphene oxide sheets to three-dimensional reduced graphene oxide aerogel, the in-situ magnetization of aerogel substrate, and the in-situ formation of HKUST-1 particles. Apart from characterizing the chemistry and structure of the designed magnetic nanocomposite (FT-IR, EDX, ICP, FE-SEM, DLS, XRD, VSM, and TG analyses), its catalytic performance was evaluated in the one-pot synthesis of biologically active 1,8-dioxo-decahydroacridine and polyhydroquinoline derivatives. The combination of magnetized reduced graphene oxide aerogel and HKUST-1 in the form of a new heterogeneous magnetic nanocatalyst was accompanied by a high synergetic catalytic effect in the symmetric and unsymmetrical Hantzsch condensation reactions. Compared to previous research studies, the pharmaceutical 1,8-dioxo-decahydroacridine and polyhydroquinoline derivatives can be synthesized using a partial amount of this nanocatalyst with a high percentage of yields in a short reaction time.

Synthesis of COF-SO3H immobilized on manganese ferrite nanoparticles as an efficient nanocomposite in the preparation of spirooxindoles

The synthesis of sulfonamide-functionalized magnetic porous nanocomposites is highly significant in chemistry due to their exceptional properties and potential as catalysts. COFs are a new class of organic porous polymers and have significant advantages such as low density, high chemical and thermal stability, and mechanical strength. Therefore, we decided to synthesize COFs based on magnetic nanoparticles, by doing so, we can also prevent the agglomeration of MnFe2O4. MnFe2O4@COF–SO3H possesses a large specific surface area, supermagnetism, and is acidic, making it an optimal catalyst for organic reactions. This particular catalyst was effectively employed in the green and rapid synthesis of various spiro-pyrano chromenes, while several analytical techniques were utilized to analyze its structural integrity and functional groups. The role of a specific site of MnFe2O4@COF–SO3H was confirmed through different control experiments in a one-pot reaction mechanism. It was determined that MnFe2O4@COF–SO3H acts as a bifunctional acid–base catalyst in the one-pot preparation of spirooxindole derivatives. The formation of a spiro skeleton in the multicomponent reaction involved the construction of three new σ bonds (one C–O bond and two C–C bonds) within a single process. The efficiency of the MnFe2O4@COF–SO3H complex is investigated in the synthesis of spirooxindoles of malononitrile, and various isatins with 1,3‐dicarbonyles. The nanocatalyst demonstrated excellent catalytic activity that gave the corresponding coupling products good to excellent yields. Furthermore, the heterogeneous magnetic nanocatalyst used in this study demonstrated recoverability after five cycles with minimal loss of activity.

Enhancement of biodiesel production using magnetic nanocatalyst CrFe2O4 from mixed waste cooking oil by an empirical model

Biodiesel has achieved widespread recognition as an unconventional energy source, despite its extra manufacturing cost and sustainable resources. Mixed waste cooking oil is one of the best feedstock for sustainable biodiesel production. This study looked at the prospect of using the easily separable magnetic nanocatalyst CrFe2O4 to reduce the manufacturing cost and being used in both esterification and transesterification simultaneously with less percentage of 0.5, produced the highest oil conversion. Before being used in conversion process, the magnetic nanocatalyst underwent Fourier transform infrared, XRD, scanning electron microscope, TGA, AFM, and BET analysis to evaluate its characteristics. Response surface methodology was employed in the conversion process and achieved 97% yield with the utilization of 0.4 (v/v) methanol/oil ratio, 0.5 wt. % catalyst concentration, 600 rpm stirring speed, and the duration of 80 min. The effect of methanol consumption and time was considerably more significant than the effect of stirring speed and catalyst usage, according to the analysis of variance. The generated biodiesel met all physicochemical characteristics with high potential, according to ASTM and EN standards. Right combinations of saturated and unsaturated fatty acids confirm the promising feasibility of the application of waste biomass feedstocks as an alternate option for the sustainable, cost effective and energy efficient synthesis of biodiesel production.

Preparation of a Novel Magnetic Nanocatalyst with High Efficiency for the Knoevenagel Condensation Reaction in Green Conditions

Preparation of a Novel Magnetic Nanocatalyst with High Efficiency for the Knoevenagel Condensation Reaction in Green Conditions

Improvement of the activity of a new nano magnetic titanium catalyst by using alkaline for refinery wastewater oxidation treatment in a batch baffled reactor

In order to reach pure water, it is essential to develop new technology for eliminating phenol from the wastewater. In this work, a nano-composite catalyst (5 % Fe2O3 + 10 % alkaline/TiO2) has been prepared and its performance to enhance the activity of catalytic wet peroxide oxidation (CWPO) process for removal of phenol has been examined. The new nano-composite catalyst is tested by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), Energy dispersive X-ray (EDX) and scanning-electron-microscopy (SEM). A baffled batch reactor is used to evaluate the activity of new nano-composite catalyst at various temperatures (30–80 °C) and reaction times (30–90 min), utilizing hydrogen peroxide (H2O2) as oxidizing agent. The new design of digital baffled batch reactor prevents the fuel swirling, thus improving agitation. The experimental data of the CWPO technology prove that the best phenol removal (95.931 %) was carried out at 80 °C, the reaction time of 90 min, and in the presence of nano-composite catalyst ((5 % Fe2O3 + 10 % alkaline)/TiO2). Modeling investigation for the CWPO is examined in order to estimate the better process kinetic. The simulation technique explains dramatic agreement in comparing with the experimental data (error < 5 %). The optimal CWPO conditions in order to achieve pure water (phenol removal >99 %) are at reaction time of 198 min, process temperature of 85 °C, and initial phenol concentration of 1000 ppm.