Magnetic Graphitic Carbon Nitride Research Articles

Enhancement of Pb(ii) adsorptive removal by incorporation of UiO-66-COOH into the magnetic graphitic carbon nitride nanosheets.

Efficient elimination of Lead (Pb(ii)) from aqueous solutions has become a crucial area of focus in the wastewater treatment industry. In this study, novel mesoporous magnetic g-C3N4/Fe3O4/UiO-66-COOH was synthesized by combining the acid-functionalized metal-organic framework (MOF) of UiO-66-COOH via a facile novel solvothermal method with magnetic graphitic carbon nitride (g-C3N4/Fe3O4) sheets to enhance Pb(ii) adsorption in water. The study investigated various influential adsorption parameters, including pH, dosage, contact time, ion concentration, and temperature. The Langmuir model, which depicts monolayer adsorption on a uniform surface, was a more suitable fit for the adsorption isotherms. The kinetics conformed to the pseudo-second-order model, indicating a chemical adsorption mechanism. According to the Langmuir model, the adsorption capacity of g-C3N4/Fe3O4/UiO-66-COOH is expected to reach a maximum of 285.8 mg L-1. This value is 2.6 times higher than g-C3N4/Fe3O4 and 1.6 times higher than UiO-66-COOH. The enhanced adsorption capacity of g-C3N4/Fe3O4/UiO-66-COOH is attributed to its superior characteristics, such as abundant functional groups and high surface area which is 2.16 times higher than g-C3N4/Fe3O4. The adsorption thermodynamics indicated that the adsorption occurred spontaneously and was characterized as exothermic. g-C3N4/Fe3O4/UiO-66-COOH material exhibited good recyclability for up to five runs.

An efficient catalytic reduction of nitroarenes over metal‐organic framework‐derived magnetic graphitic carbon nitride nanosheet

Metal–organic frameworks (MOFs) have emerged as highly viable and environmentally friendly alternatives to traditional catalysts within the catalytic family. This project delves into the investigation and subsequent reporting of the remarkable catalytic performance exhibited by magnetic Ox‐CN‐Cu‐MOF in the reduction of nitroarenes. The synthesis of magnetic Ox‐CN‐Cu‐MOF was achieved through a streamlined and intricate process, with its structure meticulously identified via various analytical methods including high‐resolution transmision electron microscopy (HRTEM), X‐ray diffraction (XRD), scanning electron microscopy/energy dispersive X‐ray spectroscopy (SEM/EDS), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET), vibrating‐sample magnetometry (VSM) and thermogravimetric (TG) analysis. Of particular significance, the loading of copper (Cu) and its potential leaching were effectively detected through inductively coupled plasma optical emission spectroscopy (ICP‐OES) analysis. The catalytic efficacy of magnetic Ox‐CN‐Cu‐MOF was evaluated during the conversion of nitro compounds o related‐amines utilizing NaBH4 as the reductant. Remarkably, the unique structure and Lewis acidic properties of copper in the metal nodes contributed to the exceptional catalytic behavior exhibited by the magnetic Ox‐CN‐Cu‐MOF catalyst, surpassing that of previously reported catalysts. Furthermore, magnetic Ox‐CN‐Cu‐MOF demonstrated exceptional recyclability, as validated through repetitive continuous usage.

Construction of heteropolyacid-anchored magnetic g-C3N4/Fe3O4@polyindole hybrids for efficient photocatalytic destruction of methyl orange and bacteria

Given the treatment of wastewater contaminated with organic dyes and bacteria, it is essential to fabricate high-performance, eco-friendly, and cost-effective photocatalytic materials. Herein, a new separatable and efficient organic–inorganic hybrid composite of tungstophosphoric acid(TPA) anchored by conducting polyindole (PID) onto magnetic graphitic carbon nitride (g-C3N4) was synthesized and used for photocatalytic degradation of methyl orange (MO) and gram-negative bacteria (P. aeruginosa) in the presence of visible LED illumination. The obtained g-C3N4/Fe3O4@PID-TPA photocatalyst was characterized by XRD, VSM, FESEM, EDX, TEM, BET surface area, DRS, PL, and FTIR methods. The g-C3N4/Fe3O4@PID-TPA catalyst (0.1 g/l catalyst dose) revealed high destruction activity (97.5%) for MO within 70 min. Due to the presence of controllable electronic structured g-C3N4, conductive PID polymer, and highly redox property of TPA heteropolyacid, boosted degradation activity was achieved by the g-C3N4/Fe3O4@PID-TPA heterostructure. Besides, the magnetic g-C3N4/Fe3O4@PID-TPA catalysts could be recycled five times without reduction in their photocatalytic performances. The g-C3N4/Fe3O4@PID-TPA catalyst demonstrates extraordinary antibacterial activity against P. aeruginosa (94.49%) at low g-C3N4/Fe3O4@PID-TPA dose. Besides, the antibacterial mechanism showed that the synergistic performance between g-C3N4/Fe3O4@PID and TPA harms the cell membranes, improves the levels of oxidative stress, and ultimately kills of P. aeruginosa. Also, the cytotoxic effect of g-C3N4/Fe3O4@PID-TPA catalyst was assessed in vitro by a MTT assay (achieving 25% to 29 % reduction in the colorectal carcinoma HCT116 cell viability). This work introduces a new outlook on developing organic–inorganic composite as photocatalysts based on heteropolyacids that serve multiple functions, particularly for environmental applications.

SERS-based recyclable immunoassay mediated by 1T-2H mixed-phase magnetic molybdenum disulfide probe and 2D graphitic carbon nitride substrate

Recently, non-metallic SERS-based immunoassay has attracted much attention due to its attractive chemical enhancement (CM), chemical stability, and biocompatibility. Herein, metallic (1T)-semiconductor (2H) mixed-phase magnetic molybdenum disulfide (MoS2) was rationally developed and combined with two-dimensional (2D) graphitic carbon nitride (g-C3N4) nanosheets to realize a SERS-based recyclable immunoassay of CA125. The Fe3O4 core promoted the reliable stacking of MoS2 nanoflakes into a flower-like shape with fully-exposed active surface. Particularly, the existence of 1T phase facilitated a noble-metal-comparable SERS activity due to the high electron density-induced charge transfer process with elevated efficiency. Moreover, a conversion from bulk to 2D nanosheet was swimmingly achieved for g-C3N4 via acid etching, whose large surface area full of active electrons and functional groups triggered an enhancement factor (EF) of 7.8 × 106. Based on a typical sandwich immunostructure, a limit of detection (LOD) as 4.96 × 10−4 IU/mL was demonstrated for CA125 in a recyclable process. Finally, such an immunosensor was employed to analyze clinical samples, indicating its prodigious potentiality in the early recognition and monitoring of cancer.

A phosphonium ionic liquid conjugated magnetic graphitic carbon nitride nanocomposite: an effective sample pretreatment tool for selenium separation and determination.

We established an innovative and easy-to-use methodology for selenium (Se) extraction and determination from real water samples utilizing a magnetic nanocomposite adsorbent (MNC-SPE) aided by an inductively coupled plasma mass spectrometry (ICP-MS) approach. The MNC-SPE adsorbent was fabricated by hybridizing Fe3O4 nanoparticles on the surface of carbon nitride nanosheets (GCN NSs) that were coated with 1-hexyl-3-methylimidazolium hexafluorophosphate ionic liquid (P-IL). A variety of techniques were used to thoroughly analyze the structural and chemical characteristics of MNC-SPE, and appear to have a great number of diverse active surface functional units (imidazole ring and -NH3+). In order to optimize the key factors affecting the Se extraction, parameters including the adsorbent dosage, contact time, eluent type, eluent volume, eluent time, and reusability of adsorbent were extensively studied. The proposed approach was validated under the optimal reaction conditions, and it showed good linearity between 0.15 and 100 pg μL-1 with a significant R2 value (R2 = 0.9994) toward Se metal. Besides, the Se limit of detection (LOD) and limit of quantification (LOQ) are 0.063 pg μL-1 and 0.147 pg μL-1, respectively. Further, by utilizing tap and river water samples, the applicability of the validated method was tested; the approach showed high Se recovery values in the range of 87.6-115.5% for the spiked real-world samples and the interday and intraday precision (RSD%) values of the approach were 4.8% (n = 6). The MNC-SPE can be regenerated and reused for four consecutive extraction-desorption cycles by employing 0.5 M NaOH eluent.

Efficient adsorption of La(III) by magnetic carbon nitride based ZIF-8 nanocomposites

The enrichment and recovery of low concentration rare earth ions from wastewater resources has become an important research direction to achieve high quality utilization of rare earth resources. In this experiment, graphitic carbon nitride was used as the substrate, which was firstly compounded with Fe3O4 to become magnetic graphitic carbon nitride material by alcohol heat method, and then in situ compounded with ZIF-8 in aqueous phase at room temperature to form the composite g-C3N4/Fe3O4@ZIF-8. Finally, the composite was characterized. The adsorption performance of g-C3N4/Fe3O4@ZIF-8 and the control g-C3N4/Fe3O4 and ZIF-8 for La(III) under various conditions was investigated by adsorption experiment. In addition, the types and mechanism of La(III) adsorption were discussed by kinetic, isothermal adsorption line and thermodynamic modeling studies. Finally, the stability performance and reusability of the composite were evaluated by regeneration experiments. The result show that g-C3N4/Fe3O4@ZIF-8 has good adsorption performance on lanthanide ions. g-C3N4/Fe3O4@ZIF-8 reached adsorption equilibrium at about 20 min. When pH is 6 and the solid–liquid ratio of adsorbent is 0.25 g/L, the adsorption amount was 176.68 mg/g. g-C3N4/Fe3O4@ZIF-8 had good selectivity for lanthanum(III), and it retains 81 % of initial adsorption performance after five times of reuse.

Fast and Eco‐Friendly Determination of Nitrite in Water Using Deep Eutectic Solvent‐Based Magnetic Bucky Gels

In this study, a novel magnetic bucky gel (MBG) was synthesized and coupled with dispersive magnetic solid-phase extraction for preconcentration and determination of trace levels of nitrite in various water samples. The MBG was prepared by dispersing magnetic graphitic carbon nitride nanocomposite (g-C3N4@Fe3O4) in a choline chloride-urea deep eutectic solvent (1:2, molar ratio). The deep eutectic solvent (DES) acts as a disperser and surface modifier for g-C3N4/Fe3O4 nanocomposites simultaneously and led to superior uptake of the analyte in a shorter time. The sorbent was characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM). The NO2− determination was carried out by UV-vis spectrophotometry. Variable factors on preconcentration of NO2− including pH, composition of MBG, contact time, sample volume, eluent type, eluent volume, and elution time were optimized. Under optimum condition, the limit of detection (LOD) was 1.56 μg L−1, the linear dynamic range extended from 5.14 to 900.00 μg L−1, the relative standard deviation (n = 5) and the preconcentration factor were 2.7% and 100, respectively. The method was successfully used for the preconcentration of NO2− ions in different water samples and gave recoveries between 89 and 103%. This article is protected by copyright. All rights reserved

Visible light photocatalytic degradation and pretreatment of lignin using magnetic graphitic carbon nitride for enhancing methane production in anaerobic digestion

The objective of this study was to investigate photocatalytic lignin degradation utilizing magnetically removable Fe3O4@g-C3N4 under visible light irradiation. Optimum conditions for lignin degradation by Fe3O4@g-C3N4 were determined. The results showed that Fe3O4@g-C3N4 can photocatalytically decompose lignin up to 90% at pH 7 after 3 h of visible light irradiation, and optimum catalyst loading in this study was 2.5 g/L. The synthesized photocatalyst exhibited stable photocatalytic activity after seven cycles. Anaerobic digestion of the photocatalytic degraded lignin for methane and biogas production was assessed with a novel approach for anaerobic digestion. In the proposed method, anaerobic digestion was conducted in total organic carbon vials with a 4 mL sample, without the need for gas collection. The key finding of this study was that the treated lignin sample outperformed the untreated lignin in terms of increased methane production by 30%.

Facile synthesis of high-efficiency magnetic graphitic carbon nitride adsorbents for the selective removal of hazardous anionic dyes in wastewater

In this study, a kind of novel magnetic composite, PEI-Fe3O4/g-C3N4, was synthesized by simple physical impregnation and used as an adsorbent to remove the anionic dye Congo red (CR) in water. The structural properties of composites were studied using Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometry (VSM), Brunauer-Emmett-Teller (BET) measurements and zeta potential techniques. PEI-Fe3O4/g-C3N4 could selectively remove anionic dyes from aqueous solutions. The adsorption kinetics and isotherms were systematically studied, and the adsorption process is in accordance with the pseudo-second-order kinetic model and Langmuir isotherm model. The thermodynamic results indicated that adsorption is a process of spontaneous heat entropy increase. CR-sorbed PEI-Fe3O4/g-C3N4 was successfully desorbed with a NaOH solution, and 0.05 M NaOH had the best desorption effect. Furthermore, PEI-Fe3O4/g-C3N4 exhibited excellent recyclability and reusability. The results of the adsorption mechanism study indicated that the excellent adsorption performance of PEI-Fe3O4/g-C3N4 was attributed to the favorable electrostatic interaction, hydrogen bonding and π-π interactions between the adsorbent and CR. In addition to its excellent adsorption properties, the prepared adsorbent showed satisfied adsorption performance in actual water samples. Predictably, the prepared adsorbent has a potential application value in the environmental field.

Preparation of MnO2 modified magnetic graphitic carbon nitride composite and its adsorption toward Pb(II) in waste water

AbstractBased on graphitic carbon nitride (CN) nanosheets, a novel MnO2 modified magnetic graphitic carbon nitride composite (MMCN) was prepared via magnetization and in-situ deposition of MnO2. Then, an array of characterizations and experiments were conducted to explore the physical and chemical properties of the synthesized MMCN material. The adsorption behavior and removal mechanism of the MMCN were also discussed intensively. The best pH value of Pb(II) of MMCN was 6. The maximum adsorption capacity of MMCN was as high as 187.6 mg/g, which was much higher than that of MCN and original CN, and removal percentage of Pb(II) was about 99%. The adsorption kinetics and isotherms were in accordance with the pseudo-second-order model and Langmuir model, respectively. The chemical adsorption of Pb(II) indicated that MMCN was a successful modified sorbent and pretty efficient to remove Pb(II) in an aqueous medium owing to the complexation and ion exchange of ample amino and hydroxyl groups. Moreover, MMCN could be separated easily from the aqueous medium under an external field after reaction with its magnetic performance.

Fabrication of graphitic carbon nitride functionalized P–CoFe2O4 for the removal of tetracycline under visible light: Optimization, degradation pathways and mechanism evaluation

In this study, nano-sized CoFe2O4 composites were prepared through co-precipitation process. Then the phosphorus-doped strong magnetic graphitic carbon nitride hybrids composites (P–CoFe2O4@GCN) was stemmed from the CoFe2O4 composites via the thermal polymerization method. The TEM results show that the CoFe2O4 nanoparticles have been successfully embedded into the graphitic carbon nitride (GCN). The BET specific surface area of P–CoFe2O4@GCN-1 could reach 36.91 m2/g, which was 5.38 times higher than that of GCN. Thus, it provided sufficient reaction active sites to enhance the photocatalytic activity for tetracycline (TC) decomposition. The results from the photocatalytic experiments showed that the degradation efficiency of TC by P–CoFe2O4@GCN-1 could reach 96.2% within 60 min, which is 3.19 times higher than that of GCN. The h+, O2•- and •OH radicals detected by the electron spin resonance (ESR) were responsible for the TC decomposition in the photocatalytic reaction system. Persulfate (PS) can further activate the hybrid mixture system, and the fitting model predicted by the response surface methodology (RSM) indicated that the maximum tetracycline removal could reach 99.6% within 30 min. In addition, the degradation intermediates of TC were detected by HPLC-MS and the photodegradation mechanism was discussed.

Magnetically recyclable magnetic biochar graphitic carbon nitride nanoarchitectures for highly efficient charge separation and stable photocatalytic activity under visible-light irradiation

The demand for developing low-cost photocatalyst that is easily separable for re-using to replace the noble metal-based photocatalysts. Herein, for the first time, we develop an innovative magnetic biochar (M-BC) based graphitic carbon nitride (g-CN) catalyst with well-designed nanoarchitectures (M-BC@g-CN) by in situ hydrothermal reaction and pyrolysis. As a photocatalyst, M-BC@g-CN catalyst delivers highly efficient and stable photocatalytic degradation for RhB dye, which is better than those of M-BC and g-C3N4 nanosheets. The rate constant (k) of M-BC@g-CN is 2.62 × 10−2 which is ~2.74 times higher than that of g-C3N4 (0.70 × 10−2 min−1). In addition, M-BC@g-CN shows a strong ferromagnetic behavior originated from Fe2O3, which can be used for rapid separation of catalyst from aqueous solution by a magnet and re-used again after the photocatalytic reaction, suggesting its outstanding eco-friendliness and recyclability. Magnetically recyclable M-BC@g-CN is also efficient for electron-hole charge separation and effectively suppresses the recombination of electron-hole pair to enhance its photocatalytic activity. Moreover, the photocatalytic mechanism of *OH and *O2− reactive species for degradation of RhB dye is revealed by the ESR measurements.

Magnetic selenium-doped graphitic carbon nitride nanocomposite as an effective catalyst support for stabilization of Cu NPs

In the present study, for the first time, a magnetic graphitic carbon nitride doped with selenium (Se-g-C3N4/Fe3O4) nanocomposite was designed and fabricated by incorporation of selenium to g-C3N4 via a facile thermal condensation technique and hybridization with Fe3O4 nanoparticles. The prepared Se-g-C3N4/Fe3O4 nanocomposite was then applied as ideal catalyst support for the immobilization of copper nanoparticles to prepare the Se-g-C3N4/Fe3O4/Cu nanocatalyst. The structure of Se-g-C3N4/Fe3O4/Cu was comprehensively identified by different spectroscopic and microscopic analyses like FT-IR, TGA, XPS, XRD, VSM, EDX, EDX mapping, FE-SEM, and AAS. The as-fabricated nanocomposite exhibited high catalytic performance in the three-component reaction using various aldehydes, secondary amines, and terminal alkynes and the corresponding propargylamines were gained in good to excellent yields (65–98%) under solvent-free conditions at 110 °C for 3.5 h. Also, this copper nanocatalyst exhibited good stability and could be easily separated using an external magnetic field and reused four times with a slight decrease in its activity. The excellent catalytic performance and stability of the nanocatalyst can be related to the effective interaction between the support and the well-dispersed copper nanoparticles.

Greener and regioselective ring opening of epoxides with TMSCN using potassium salts of magnetic carbon nitride

Potassium salts of magnetic graphitic carbon nitride (Fe3O4@g-C3N4-K) synthesized and proved to be a green and recyclable catalyst for rapid and regioselective ring opening of epoxides with TMSCN, yielding the β-hydroxynitrile ring-opened products under mild reaction conditions. It is manageable to large-scale preparation with simple instruments and gives the desired compounds in short reaction times with good-to-excellent yields (73–95%) under solvent-free conditions. Magnetic separation protocol has used to achieve a simple separation and reuse of catalysts from unpurified reaction mixtures using external magnets without loss of catalytic operation after five cycles.

Pd on poly(1-vinylimidazole) decorated magnetic S-doped grafitic carbon nitride: an efficient catalyst for catalytic reduction of organic dyes

A novel magnetic catalyst, (SGCN/Fe3O4/PVIs/Pd) was synthesized by growing of poly(1-vinylimidazole) on the surface of ionic liquid decorated magnetic S-doped graphitic carbon nitride, followed by stabilization of palladium nanoparticles. Catalytic activity of the prepared heterogeneous catalyst was explored for the catalytic reduction of hazardous dyes, methyl orange and Rhodamine B, in the presence of NaBH4. Besides, the effects of the reaction variables on the catalytic activity were investigated in detail. The kinetics study established that dye reduction was the first order reaction and the apparent activation energy was calculated to be 72.63 kJ/mol and 68.35 kJ/mol1 for methyl orange and Rhodamine B dyes, respectively. Moreover, ΔS# and ΔH# values for methyl orange were found to be − 33.67 J/mol K and 68.39 kJ/mol respectively. These values for Rhodamine B were − 45.62 J/mol K and 65.92 kJ/mol. The recycling test verified that the catalyst possessed good stability and reusability, thereby making it a good candidate for the catalytic purposes. Furthermore, a possible catalytic mechanism for dye catalytic reduction over SGCN/Fe3O4/PVIs/Pd was proposed.

Highly efficient and selective removal of cadmium from aqueous solutions based on magnetic graphitic carbon nitride materials with molecularly imprinted polymers

Poly (N-isopropyl acrylamide) grafted and modified g-C3N4 magnetic imprinted ions polymers (IIP) was prepared by selecting Cd2+ as a template ion. Some techniques were applied to characterize morphology and property of IIP including Scanning electron microscope (SEM), Thermo-gravimetric analyzer (TGA), Infrared Spectroscopy (IR) and Vibrating sample magnetometer (VSM). The adsorption capacity of IIP for various metal ions was contrasted and the influence of different factors for adsorption of Cd2+ was investigated. These results showed that the IIP was the large block morphology and had selectivity for Cd2+ adsorption. The experimental data were well described by Langmuir isotherm model and pseudo-second-order model. The predicated maximum adsorption capacity of IIP for Cd2+ is 258.35 mg/g. The maximum adsorption capacity obtained from the experiment is 184 mg/g (initial concentration of 250 mg/L, pH=6.0, contact time for 180 min) at 303 K. The parameters of adsorption activation energy suggested that there is chemisorption and physical adsorption on the adsorption of Cd2+. The results of adsorption mechanism suggested that IIP selectively adsorbs Cd2+, which not only relies on ion holes, but also depends on functional groups. The adsorption capacity of IIP for Cd2+ could still keep 84% in the fifth consecutive adsorption-regeneration cycle. Hence, IIP would be regarded as a selective and high adsorption capacity magnetic adsorbent in removal of Cd2+ from wastewater.

Sulfonic acid-functionalized graphitic carbon nitride composite: a novel and reusable catalyst for the one-pot synthesis of polysubstituted pyridine in water under sonication

Graphitic carbon nitride as an interesting sustainable soft nanomaterial has drawn broad interdisciplinary attention because of unique electronic structure and chemical stability. An ultrasound-assisted preparation of a series of polysubstituted pyridines in the presence of a polar and strongly acidic sulfonated magnetic graphitic carbon nitride (Fe3O4@g-C3N4-SO3H) under milder and faster reaction conditions in water as a green medium was reported. One-pot sequential multicomponent reaction of aromatic aldehydes with acyclic and cyclic ketones, malononitrile and ammonium acetate was afforded the pyridine derivatives in good-to-excellent yields. In view of eco-friendly and economic considerations, this approach offers a straightforward and convenient route to generate biologically active pyridine derivative in an environmentally friendly manner. The Fe3O4@g-C3N4-SO3H showed high stability and reusability over several reaction sets without noteworthy loss of activity, and thus, this method is a cheap and eco-friendly procedure.

Magnetic graphitic carbon nitride nano-composite for ultrasound-assisted dispersive micro-solid-phase extraction of Hg(II) prior to quantitation by atomic fluorescence spectroscopy

A nanosheet structure of Fe3O4/g-C3N4 magnetic composite has been prepared and utilized as adsorbent for the ultrasound-assisted dispersive magnetic micro-solid-phase extraction of the ultra-trace inorganic mercury [Hg(II)]. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Fouries transform infrared spectroscopy images manifested that the hydrothermal systhesis promoted the binding of Fe3O4 particles with g-C3N4. The enrichment performance of composites depended on their compositions, and the recovery of Hg(II) on C-m30 (with Fe3O4/g-C3N4 mass ratio 2:3) was higher than that on other ratios. Recorded data showed that ultrasound wave was an effective method for reducing the agglomeration of magnetic materials and enhancing their adsorption properties. The Hg signal obtained by 80% power input is 3.2 times stronger than the signal by strring mode. X-ray diffraction characterization of the recovered adsorbent showed that g-C3N4 needed to be updated after repeated use for four times. In addition, competitive adsorption may be main factor affecting the inhibitory effect of high concentration methylmercury on inorganic mercury. Under the optimized conditions, the detection limit of the proposed method was 1.4 ng L−1 and relative standard deviation of 4.6% for 0.05 μg L−1 Hg(II) was obtained. The linear calibration range was 0.005–0.4 μg L−1. The accuracy of the method was verified through analysis of the certificated reference materials. The proposed method has been applied in the determination of inorganic Hg in natural water samples.

Experimental and quantum chemical study on nano-copper immobilized on magnetic graphitic carbon nitride core shell particles; a reusable heterogeneous catalyst toward reduction of nitro arenes

A new magnetic material, which named CuFe2O4@SiO2@g-C3N4/Cu with a core/shell morphology has been designed and synthesized. For the first time ever, the mixture of carbon and g-C3N4 layer was applied as an effective linker for immobilization of Cu metal on the catalyst. The physiochemical properties of the catalyst were identified by XRD, FT-IR, VSM, FE-SEM and TEM characterization techniques. The reduction of nitro compounds to the corresponding amines was investigated in the presence of NaBH4 at 55 °C in water. Quantum chemical study reveals that the addition of Cu atoms to the g-C3N4 layer induce a slight structural deformation via changing the bond lengths and bond orders, also the type of interaction of Cu atoms and nitrogen atoms of g-C3N4 is mainly electrostatic in nature. Induced pattern of charge distribution provided by Electrostatic Potential Map exhibits the attractive regions for electrophiles and nucleophiles interacting with this system.

Magnetic covalent hybrid of graphitic carbon nitride and graphene oxide as an efficient catalyst support for immobilization of Pd nanoparticles

For the first time a magnetic carbon based hybrid catalyst, Pd@g-C3N4-Fe-GO, is prepared through covalent conjugation of magnetic graphitic carbon nitride and graphene oxide followed by incorporation of Pd nanoparticles. First, the formation of the catalyst was confirmed via XRD, TG, BET, TEM, FTIR, ICP and VSM analyses and then its catalytic activity for promoting Suzuki and Sonogashira coupling reactions under mild reaction condition was investigated. To elucidate whether hybridization of two carbon materials could improve the catalytic activity, the catalytic activity of the catalyst was compared with the control catalysts (Pd@g-C3N4 -GO, Pd@g-C3N4-Fe, Pd@ Fe-GO, Pd@g-C3N4, Pd@GO and the GO/g-C3N4 physical hybrid). Moreover, the role of magnetic nanoparticles in the catalytic performance was confirmed. Notably, the catalytic activities of the catalyst and the control sample prepared via physical hybridization of two carbon materials were compared to confirm the effect of covalent conjugation on the catalytic activity. Moreover, the study of the substituent effect of p-substituted phenyl iodides was considered by Hammett plot, which revealed a beneficial effect of electron-withdrawing side groups for the CC coupling reaction. Finally, the recyclability of Pd@g-C3N4-Fe-GO as well as leaching of Pd and magnetic nanoparticles was studied.