Recycling Experiments Research Articles

Simultaneously Cationic and Anionic Dyes Elimination via Magnetic Hydrochar Prepared from Copper Slag and Pinewood Sawdust.

In practical wastewater, cationic and anionic dyes usually coexist, while synergistic removal of these pollutants is difficult due to their relatively opposite properties. In this work, copper slag (CS) modified hydrochar (CSHC) was designed as functional material by the one-pot method. Based on characterizations, the Fe species in CS can be converted to zero-valent iron and loaded onto a hydrochar substrate. The CSHC exhibited efficient removal rates for both cationic dyes (methylene blue, MB) and anionic dyes (methyl orange, MO), with a maximum capacity of 278.21 and 357.02 mg·g-1, respectively, which was significantly higher than that of unmodified ones. The surface interactions of MB and MO between CSHC were mimicked by the Langmuir model and the pseudo-second-order model. In addition, the magnetic properties of CSHC were also observed, and the good magnetic properties enabled the adsorbent to be quickly separated from the solution with the help of magnets. The adsorption mechanisms include pore filling, complexation, precipitation, and electrostatic attraction. Moreover, the recycling experiments demonstrated the potential regenerative performance of CSHC. All these results shed light on the co-removal of cationic and anionic contaminates via these industrial by-products derived from environmental remediation materials.

The Synthesis of Glycerol Carbonate from Glycerol and Carbon Dioxide over Supported CuO-Based Nanoparticle Catalyst.

A series of supported CuO-based nanoparticle catalysts were prepared by the impregnation method and used for the synthesis of glycerol carbonate from glycerol and CO2 in the presence of 2-cyanopyridine as a dehydrant and DMF as a solvent. The effects of supports (activated alumina, silicon dioxide, graphene oxide, graphene, and activated carbon), CuO loading amount, calcination temperature, and reaction parameters on the catalytic activity of the catalyst were investigated in detail. XRD, FTIR, SEM, BET, and CO2-TPD were used for the characterization of the prepared catalysts. It is found that CuO/Al2O3 shows a higher catalytic activity, which depends on the CuO loading amount and calcination temperature. The surface area and number of basic sites of the catalyst exhibit a crucial effect on the catalytic activity of CuO/Al2O3. Furthermore, there is a synergistic effect between the catalyst and 2-cyanopyridine where the former has a higher activation ability for glycerol and the latter acts not only as a dehydrant, but also as a promoter for CO2 activation. Recycling experiments reveal that this catalyst can be reused for at least five cycles without any inactivation. Based on the experiment results and FTIR characterization, a possible reaction mechanism for the carbonylation of glycerol and CO2 is proposed.

Fabrication and characterization of Fe3O4@SiO2-Imine/Thio-Cu(II) nanomaterial as a novel and efficient magnetically reusable catalyst for the synthesis of N-aryl sulfonamides

In this paper, we synthesized Fe3O4@SiO2-Imine/Thio-Cu(II) nanomaterial and studied its catalytic activity in the synthesis of N-aryl sulfonamides via the reaction of various aryl iodides and sulfonamides under eco-friendly conditions. The structure of the Fe3O4@SiO2-Imine/Thio-Cu(II) nanomaterial was characterized by FT-IR, SEM, TEM, EDX, XRD, VSM, AAS, and ICP-OES techniques. Recycling experiments revealed that the Fe3O4@SiO2-Imine/Thio-Cu(II) nanocatalyst could be easily recovered by a simple magnetic separation and recycled at least seven times without deterioration in catalytic activity. High reusability, simple recovery of catalyst, high yields, mild conditions, performance of reactions in water and simple operation are several significant advantages of this methodology.

Magnetically Separable Mixed-Phase α/γ-Fe2O3 Catalyst for Photo-Fenton-like Oxidation of Rhodamine B

Iron oxides are widely used as catalysts for photo-Fenton-like processes for dye oxidation. In this study, we report on the synthesis of an α/γ-Fe2O3 mixed-phase catalyst with magnetic properties for efficient separation. The catalyst was synthesized using glycine–nitrate precursors. The synthesized α/γ-Fe2O3 samples were characterized using scanning electron microscopy, X-ray diffraction spectroscopy (XRD), Raman shift spectroscopy, X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometer (VSM). The diffraction peaks were indexed with two phases, α-Fe2O3 as the main phase (79.6 wt.%) and γ-Fe2O3 as the secondary phase (20.4 wt.%), determined using the Rietveld refinement method. The presence of Fe2+ was attributed to oxygen vacancies. The mixed-phase α/γ-Fe2O3 catalyst exhibited remarkable photo-Fenton-like degradation performance for Rhodamine B (RhB) in neutral pH. The effects of operating parameters, including H2O2 concentration, catalyst concentration, and RhB concentration, on the degradation efficiency were investigated. The removal rates of color were 99.2% after 12 min at optimal conditions of photo-Fenton-like oxidation of RhB. The sample exhibited a high saturation magnetization of 28.6 emu/g. Additionally, the α/γ-Fe2O3 mixed-phase catalyst showed long-term stability during recycle experiments, with only a 5% decrease in activity.

Bifunctional strontium-doped barium oxide nanorods as promising photocatalysts and electrodes for energy storage applications

It is critical to design highly efficient, clean, and renewable energy sources to replace fossil fuels and mitigate their harmful impacts on the environment. Two effective approaches for replacing fossil fuels are electrochemical energy storage devices and photocatalysis. Herein, for the first time, strontium-doped barium oxide nanorods (Sr-BaO NRs) were synthesized using a facile co-precipitation technique and characterized with different analytical techniques to explore their physical, electrochemical, and photocatalytic properties. The successful formation of Sr-BaO NRs and their structural variations were confirmed by XRD, Raman, and FT-IR results. UV–Vis analysis showed that the bandgap of BaO was decreased by increasing the Sr concentration. SEM micrographs confirmed the formation of nanorods. The findings of the photocatalytic experiments showed excellent photodegradation efficiencies against methylene blue (MB) (95.55 %), methyl orange (MO) (98 %), and rhodamine-B (RhB) (96.33 %) dyes after 60, 70, and 90 min, respectively under UV light irradiation. Higher stability up to five cycles was shown in the recyclability experiments employing the optimized catalyst. The electrochemical properties of Sr-BaO NRs were also studied for the first time. 4 % Sr-BaO NRs offered an exceptional specific capacitance of 925.2 F/g, and a good energy density of 32.12 Wh/Kg with a higher power density of 750 W/kg at a current density of 3 A/g. The development of such affordable and efficient photocatalysts and electrode materials is desired for future environment protection and energy storage applications.

Preparation of Thiadiazole Modified UiO-68-CdS Composites for RhB Degradation under Visible Light Irradiation

In this paper, the photosensitive Zr-MOF material Thiadiazole-modified UiO-68 (UiO-68N2S) was used to prepare CdS@UiO-68N2S composites by MOF post-reaction. The chemical composition is characterized using PXRD, FT-IR, XPS, SEM, and TGA. Rhodamine B was used as the model dye for photocatalytic degradation to evaluate the performance of CdS@UiO-68N2S under visible light irradiation. Experimental results show that the degradation rate of a 25 mg/L RhB solution (10 mL) reached 94% with 10 mg CdS@UiO-68N2S as a photocatalyst under blue light irradiation in 13 h at room temperature. The mechanism study revealed that O2•− is the reactive oxygen species for the degradation of Rhodamine B. Recycle experiments showed that CdS@UiO-68N2S can be reused for three rounds without a significant reduction of its catalytic function.

Insight into mass transfer during adsorption of geniposidic acid onto a fixed-bed column by numerical simulation considering influence of operating conditions on column adsorption performance

In this work, the adsorption rate of geniposidic acid (GSA) on a fixed-bed column packed with porous adsorbents was studied, thoroughly by a Fick pore diffusion model based on numerical simulation and 3D visualization. Adsorption breakthrough curves of GSA were studied experimentally, under various operation conditions such as feeding concentrations, flow rates and packed column aspect ratio. For ion exchange adsorption of GSA onto the adsorbent used in this paper, a maximum adsorption capacity reached 637.5 mmol·L−1 at 298.5 K. Modeling method for an adsorption packed column was based on the coupling of mass transfer equations with a steady velocity field obtained from Navier-Stokes equation. A finite element method was adopted by COMSOL Multiphysics with proper mesh refinement, to solve the equation system. Moreover, the influences of operation conditions on the magnitude and direction of mass fluxes induced by convection and diffusion were analyzed in details. 3D data of Mass fluxes proved that the existence of forming period and transferring period of mass transfer zone (MTZ), which are important knowledge for comprehending the dynamics of adsorption process. The magnitude of convection flux was almost 107–108 times larger than that of pore diffusion flux. Average pore diffusion diffusivities of GSA and Cl− were fitted to be 5.19 × 10−10 and 1.71 × 10−9 m2·s−1, while their maximal mass fluxes were 9.366 × 10−3 and 3.926 × 10−3 mol m−2·s−1 in simulations, respectively. Finally, adsorption and elution recycle experiments proved the feasibility of the novel GSA adsorption technology in the future scaling-up process.

Enhanced Decomposition of H2O2 Using Metallic Silver Nanoparticles under UV/Visible Light for the Removal of p-Nitrophenol from Water

Three Ag nanoparticle (NP) colloids are produced from borohydride reduction of silver nitrate in water by varying the amount of sodium citrate. These nanoparticles are used as photocatalysts with H2O2 to degrade a p-nitrophenol (PNP) solution. X-ray diffraction patterns have shown the production of metallic silver nanoparticles, whatever the concentration of citrate. The transmission electron microscope images of these NPs highlighted the evolution from spherical NPs to hexagonal/rod-like NPs with broader distribution when the citrate amount increases. Aggregate size in solution has also shown the same tendency. Indeed, the citrate, which is both a capping and a reducing agent, modifies the resulting shape and size of the Ag NPs. When its concentration is low, the pH is higher, and it stabilizes the formation of uniform spherical Ag NPs. However, when its concentration increases, the pH decreases, and the Ag reduction is less controlled, leading to broader distribution and bigger rod-like Ag NPs. This results in the production of three different samples: one with more uniform spherical 20 nm Ag NPs, one intermediate with 30 nm Ag NPs with spherical and rod-like NPs, and one with 50 nm rod-like Ag NPs with broad distribution. These three Ag NPs mixed with H2O2 in water enhanced the degradation of PNP under UV/visible irradiation. Indeed, metallic Ag NPs produce localized surface plasmon resonance under illumination, which photogenerates electrons and holes able to accelerate the production of hydroxyl radicals when in contact with H2O2. The intermediate morphology sample presents the best activity, doubling the PNP degradation compared to the irradiated experiment with H2O2 alone. This better result can be attributed to the small size of the NPs (30 nm) but also to the presence of more defects in this intermediate structure that allows a longer lifetime of the photogenerated species. Recycling experiments on the best photocatalyst sample showed a constant activity of up to 40 h of illumination for a very low concentration of photocatalyst compared to the literature.

Efficient SO2 capture and conversion to cyclic sulfites by protic ionic liquid-based deep eutectic solvents under mild conditions

SO2 capture has been a research hotspot targeting mitigation of SO2 emission, and the subsequent conversion of SO2 is an ingenious protocol, which can avoid regeneration of absorbents and realize utilization of SO2 simultaneously. To this end, a series of protic ionic liquids (PILs)-based deep eutectic solvents (DESs) composed of N-alkylimidazole hydrochloride-based PILs and azoles were designed for the capture and conversion of sulfur dioxide. Among them, [MImH]Cl/2-MIm (1:1) exhibited SO2 loading capacity as high as 1.45 g/g at 1.0 bar and 20 °C, and remarkable SO2 solubility up to 0.56 g/g were achieved at low concentrations (0.6 vol%, 20 °C). In particular, the absorbed SO2 can be directly converted to cyclic sulfites through cycloaddition reaction catalyzed by these DESs under very mild condition (30 °C and 1.0 bar of SO2) without any solvent of additive. By using gas chromatograph-mass spectrometer (GC-MS), yields of cyclic sulfites were determined to be excellent for styrene oxide (98 %) and 1,2-epoxybutane (97 %), and moderate for the sterically hindered epoxides (56 %–76 %). Recycling experiments proved that these DESs maintained good absorption and catalytic performance after five cycles. Furthermore, the absorption and catalytic mechanism were studied by Fourier transform infrared (FT-IR), nuclear magnetic resonance (NMR) spectroscopies, and theoretical calculations, revealing the multi-site absorption mechanism and synergic catalysis in PIL-based DES.

Application of CdTe quantum dots sensitized titanate nanotubes in photocatalytic degradation of organic pollutants under visible light irradiation

The use of solar-driven photocatalysis for the degradation of recalcitrant organic waste from water is a promising and environmentally friendly technology to meet the challenge of mitigating increasing global pollution. This paper presents a new composite of layered H2Ti3O7 hydrothermal nanotubes (TNT) with cadmium telluride quantum dots prepared by the simple mixing suspensions of both components in TNT/CdTe-QDs ratios in the range of 1:0.005–1:0.03. The products were characterized by X-ray diffraction, spectroscopic techniques such as Fourier transform infrared, Raman scattering, UV–visible diffuse reflectance, photoluminescence, and X-ray photoelectron spectroscopy, as well as by scanning and transmission electron microscopy. The photocatalytic performance of the products was tested by photocatalytic degradation of two molecular models of contaminants, methyl orange (MO) and 4-chlorophenol (4-CP). Nearly 100 % removal of organic contaminants was achieved and the degradation rate of MO and 4-CP under simulated sunlight in the presence of QDs was approximately five and four times faster than using TNT alone, respectively. The degradation rate response in the presence of specific radical scavengers corresponds to a direct Z-scheme photocatalysis. Recycling experiments demonstrated a structurally stable catalyst that maintains its efficiency after five irradiation cycles. Photoelectrochemical and photocurrent measurements validated the synergistic effect observed, reflecting that heterojunction promotes the transfer of photogenerated electrons and holes, decreasing recombination changes and improving photocatalytic activity.

Recyclable Silver-Catalyzed Selective Hydrogenation of Imides to Primary Amines via Dual C-N Bond Cleavage.

We report the first heterogeneous catalytic hydrogenation of N-substituted imides and polyimide to generate primary amines, diols, and lactones. Catalyzed by Ag/TiO2, this reaction proceeded smoothly in high yields and selectivities for N-alkyl and N-aryl phthalimides and N-aryl succinimides, which also had activity for the degradation of waste polyimide plastics. In contrast to the typical Gabriel process, this reaction does not need any toxic reagent, and the byproducts are also very useful. Recycling experiments showed that the catalyst Ag/TiO2 could be easily recovered without a decrease in catalytic activity.

Performance of molybdenum vanadate loaded on bentonite for retention of cesium-134 from aqueous solutions

This article studied the sorption behavior of Cs(I) ions from aqueous solutions onto molybdenum vanadate@bentonite (MoV@bentonite) composite. MoV@bentonite has been fabricated using the precipitation method and was characterized by different analytical tools including, FT-IR, XRD, and SEM attached with an EDX unit. The sorption studies applied on Cs(I) ions include the effect of contact time, pH, initial metal concentrations, ionic strength, desorption, and recycling. The experimental results revealed that in the adsorption process carried out after equilibrium time (300 min), saturation capacity has a value of 26.72 mg·g−1 and the sorption of Cs(I) ions is dependent on pH values and ionic strength. Sorption kinetic better fit with the pseudo-second-order model; sorption isotherms apply to Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherm models. Data of thermodynamic parameters indicate that sorption is spontaneous and endothermic. Recycling experiments show that MoV@bentonite could be used for 7 cycles and the best eluant for the recovery of Cs(I) ions is 0.1 M HCl (76.9%). All the obtained data clarify that MoV@bentonite is considered a promising sorbent for the sorption of Cs(I) ions from aqueous solutions.

Solid‐Phase Lipase‐CuNPs Biohybrids as Catalysts for One‐Pot Parallel Synthesis of 2,3,4‐Triacetyl‐D‐Gluconic Acid

AbstractSolid‐phase lipase/metal nanobiohybrids, generated by growth of copper nanoparticles on enzyme matrixes immobilized on graphene, were used as heterogeneous catalysts with dual‐activity for the regioselective production of 2,3,4‐triacetyl‐D‐gluconic acid from α‐peracetylated‐glucose in a one‐pot parallel process combining a lipase‐mediated regioselective hydrolytic monodeprotection with a metal‐catalyzed oxidation in aqueous media. A novel synthetic strategy, based on the in situ fabrication of Cu nanoparticles induced by lipase molecules specifically immobilized on a multi‐layer graphene material by interfacial adsorption fixing them in the active open conformation, has been described. Thermomyces lanuginosus lipase was firstly used to prepare the functionalized multi‐layer graphene from graphite as a biographene preparation (Biographene, BIOG), support used to successfully immobilize Candida rugosa lipase (CRL). This immobilized form BIOG‐CRL was further used to create successful active bifunctional enzyme‐metal nanoarchitectures. Two different Cu‐lipase hybrids were synthesised, where Cu species and nanoparticles size were different depending on the methodology. Regioselectivity and stability of the hybrids were evaluated successfully in the production of monosaccharide building blocks, besides the robustness of the hybrids in recyclability experiments. These findings highlight the potential of these solid‐phase nanoarchitectures as useful tools in the synthesis of complex glycoderivatives for use in food, medicine, and cosmetics.

Cerium and carbon-sulfur codoped mesoporous TiO2 nanocomposites for boosting visible light photocatalytic activity

Ce and C–S codoped mesoporous TiO2 nanocomposites were synthesized via a sol-gel method integrated with an evaporation-induced self-assembly approach. The basic physicochemical characteristics of the synthetic samples were analyzed via a series of characterization techniques. The results reveal that C–S and Ce codoping on mesoporous TiO2 enhances the photocatalytic activity owing to the synergistic effect caused by narrowing the band gap, enhancing adsorption, trapping and transferring the excited e–/h+ pairs and suppressing the recombination of e–/h+ pairs. Furthermore, the obtained C,S–TiO2/CeO2 materials exhibit large specific surface areas and numerous pores which not only effectively improve the adsorption-enrichment capability, but also supply multi-dimensional mass and electron transfer channels. The photodegradation efficiency of RhB by C,S–TiO2/CeO2 within 40 min is nearly 100%, and its degradation efficiency is 6.63 times that of undoped TiO2. Recycling experiments show that mesoporous C,S–TiO2/CeO2 shows excellent recoverability and stability. Furthermore, by trapping experiments, •O2–, h+ and •OH are the predominant active species and a possible reaction mechanism is proposed.

Innovative three-phase partitioning based on deep-eutectic solvents and sugars (sugaring-out effect) for cucumber peroxidase purification

Traditional three-phase partitioning (TPP) systems used for extracting and purifying bioactive substances typically consist of t-butanol and ammonium sulfate. However, the use of volatile and flammable organic solvents and high-concentration inorganic salts results in environmental pollution. Therefore, an innovative TPP based on deep eutectic solvents (DESs) and sugars (sugaring-out effect) was used to extract and preliminarily purify cucumber peroxidase (POD). Various factors affecting the extraction were optimized using response surface methodology (RSM). DES-8 (menthol: octanoic acid = 1:1) and sucrose were selected as the optimal constituents of TPP. Under these conditions, the sucrose concentration was 36% (w/v), DES: crude extract (v/v) was 1.4:1, system pH was not adjusted, extraction time was 6 min, and extraction temperature was 31 °C; the enzyme recovery and purification fold reached 84.53% and 5.28, respectively. Recycling experiments demonstrated that the DESs can be well recycled and reused after five recycles. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was used to analyze cucumber POD, which showed that the TPP system achieved primary purification of cucumber POD. This TPP is much greener and more efficient than traditional TPP systems and shows great application potential in the enzymes and proteins separation field.

Construction of 3D flower-like Bi5O7I/Bi/Bi2WO6 heterostructure decorated NiFe2O4 nanoparticles for photocatalytic destruction of Levofloxacin in aqueous solution: Synergistic effect between S-scheme and SPR action

Promoting the separation activity of photo-induced carriers via the design of heterostructure photocatalysts remains a vital challenge. In the present study, multistep strategies were developed to construct the Bi5O7I/Bi/Bi2WO6/NiFe2O4 heterojunction by in situ growth of Bi/Bi2WO6 and NiFe2O4 species on the surface of Bi5O7I microspheres, forming a 3D flower-like structure as verified by characterization technologies. The developed heterojunction reflected superior photodegradation activity (97.5% in 90 min) toward levofloxacin (LEV) under visible light irradiation. The enhanced photodegradation activity of the Bi5O7I/Bi/Bi2WO6/NiFe2O4 nanocomposite could be attributed to the synergistic outcomes of the S-scheme mechanism and the plasmonic action of Bi metal in one system. Furthermore, the Bi metal can directly harvest the simulated sunlight under the surface plasmon resonance (SPR) action, which contributes to generating a large number of electron-hole pairs. Some influencing factors like pH, LEV concentration, and catalyst loading were also discussed. The photocatalytic degradation pathways of LEV were investigated depending on the detected intermediate products. The radical experiment and ESR results stated that the major contribution of •OH, •O2−, and h+ radicals in LEV destruction. The recyclability experiments indicated the excellent stability and facile reusability of the magnetic Bi5O7I/Bi/Bi2WO6/NiFe2O4 composite. Finally, the photocatalytic mechanism for LEV destruction was clarified in terms of trapping experiments and band-gap discussions. This work introduces a clear technology to fabricate a quaternary S-scheme heterojunction boosted by the plasmonic effect of Bi metal to accelerate the charge separation ability and create a powerful redox potential to achieve a desirable LEV treatment process.

Carbon/Mn3O4/SrTiO3 microsphere photocatalyst for the efficient removal of high‐concentration methylene blue from water

AbstractBACKGROUNDWith the development of the textile and dye industry, a large amount of dye wastewater has been discharged. Semiconductor photocatalysis has been widely used in the treatment of environmental pollution, so it is very important to study efficient, nontoxic and stable photocatalysts.RESULTSIn this study, a microspherical activated carbon/Mn3O4/SrTiO3 composite photocatalyst with high catalytic activity was synthesized using sol–gel and chemical precipitation methods. The photocatalyst was characterized through X‐ray diffraction, scanning and transmission electron microscopy, energy dispersive spectroscopy, X‐ray photoelectron spectroscopy, photoluminescence, Electrochemical impedance spectroscopy, electron paramagnetic resonance spectroscopy and photocurrent measurements, and the effects of the initial methylene blue (MB) concentration and pH on the catalytic performance of the photocatalyst were investigated. The results revealed that the MC/Mn3O4/SrTiO3 composite has large light absorbance, and it can effectively inhibit photoinduced electron–hole pair recombination. The catalyst exhibited high photocatalytic degradation activity, and the degradation efficiency of MB at 300 ppm and pH 7 reached 99% after 80 min of UV light irradiation. The photodegradation process conformed to the pseudo‐first‐order kinetic model. Recyclability experiments showed that MC/Mn3O4/SrTiO3 composite has high stability, and the degradation rate of MB is > 70% after three repeat uses.CONCLUSIONSThis work provides a new method for finding low‐cost, high‐performance materials that can be modified and put into industrial use. © 2023 Society of Chemical Industry (SCI).

Sustainable production of dimethyl-protected cyclic lysine over Pd/m-Al2O3-Si catalysts and its application in synthesis of antibacterial nylon‑6 copolymers

Antibacterial monomers are prerequisites for synthesizing antibacterial polymers, especially during the current COVID-19 pandemic. Dimethyl-protected cyclic lysine (DMCL) is a promising functional monomer for nylon-6 based self-cleaning antibacterial polymers. However, the production of DMCL still faces formidable challenges, such as harsh reaction conditions and low catalyst activities. In this study, we developed a Pd/m-Al2O3-Si catalyst, which exhibited high efficiency in converting α-amino-ε-caprolactam (α-ACL) to DMCL, affording a yield of as high as 97.1% at 100 °C and 1 MPa H2. The lack of Brönsted acid sites on the catalyst surface facilitated the formation of DMCL and suppressed undesirable hydrolysis or cracking by-products from the lactam-based reactant. The recycled experiments showed that Pd/m-Al2O3-Si performed excellent stability and physical strength with essentially no damage to its microspheres after the reaction. The nylon‑6 copolymers produced from the as-synthesized DMCL exhibited similar structure and thermal stability with pure nylon-6, showing great potential in synthesizing the self-cleaning antibacterial polymers. This work provides a sustainable and efficient method for producing DMCL and other lysine-based antibacterial monomers, showing a great prospect for the utilization of bio-based chemicals in synthesizing functional polymers.

A Novel and Efficient Magnetically Recoverable Copper Catalyst for Synthesis of Symmetrical Diaryl Selenides and Sulfides

Diaryl sulfides and selenides are ubiquitous chemical structures found in natural products, synthetic organic semiconductors, agricultural, and various biologically active molecules. Therefore, the development of novel and efficient catalytic systems for the preparation of diaryl sulfides and selenides is an important challenge in organic synthesis. In this paper, we wish to report the construction of a novel and efficient nanomagnetic copper nanocatalyst through the immobilization of Cu(OAc)2 on the surface of magnetic nanoparticles modified with Imine-Thiazole as ligand. The as-fabricated Fe3O4@SiO2-(Imine-Thiazole)-Cu(OAc)2 nanocomposite shown high catalytic activity in the C-Se (83%-98%) and C-S bond formation at 100 °C. To the best of our knowledge, this is the first report on the use of magnetically reusable copper nanocatalyst for the synthesis of diaryl selenides and sulfides via the reaction of triarylbismuthanes with elemental Se or S powder under aerobic conditions. Recycling experiments revealed that the copper nanocatalyst could be easily recovered by a simple magnetic separation and recycled at least eight times without deterioration in catalytic activity.

Microemulsion synthesis of Ga and Sr doped BiFeO3 nanoparticles and evaluation of their ferroelectric, optical, dielectric and photocatalytic properties

A series of Ga and Sr doped bismuth ferrite (BiFeO₃) was synthesized using a facile microemulsion technique and characterized using XRD, SEM, Raman, PL and UV–vis techniques. The XRD and Raman study revealed the rhombohedral phase of Bi1-xSrxFe1-xGayO3 with R3‾c space group. The average crystalline size was in range of 28–42 nm. From P-E loop, the saturation polarization (Ps), coercivity (Hc) and remanence (Pr) were determined and value of Pr and Ps increased with increasing dopant contents. Furthermore, there was a decline in dielectric loss with increased frequency and dopant content. The PL revealed that the highly substituted material had lower re-combination rate and higher charge (e−-h+) separation, which was finally responsible for its enhanced photo-catalytic activity. For Ga and Sr doped BiFeO₃, UV–Vis absorption edge exhibited substantial red shift thus reducing bandgap from 1.91 to 1.19 eV for highest doped composition. Finally, the photocatalytic activity of the material was investigated using methyl orange (MO) as model contaminant. Bi1-xSrxFe1-xGayO3 exhibited much better photocatalytic efficiency and degraded 87% dye in comparison to pristine BiFeO3 (66%) within 70 min under solar light. Also, stability of samples was demonstrated through re-cycling experiment. Bi1-xSrxFe1-xGayO3 had higher stability and reusability compared to BiFeO₃. Based on these findings, Bi1−xSrxFe1−yGayO3 material may find use in high frequency devices and photo-catalytic applications for treatment of industrial wastes due to its promising dielectric and photo-catalytic outcomes.