Rhodamine B Solution Research Articles

Efficient RhB degradation using MnFe2O4/g-C3N4 composites under visible light irradiation

The MnFe2O4/g-C3N4 composites with promising photocatalytic activity were successfully prepared in this study. The structure and morphology of the as-prepared composites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), and the photocatalytic activity was evaluated through the degradation of rhodamine B (RhB). It was found that the composites with 30 wt% MnFe2O4 possessed 2.64 times higher photocatalytic activity than that of pure g-C3N4, and the degradation rate of 30 mg/L RhB solution could reach 97.2% in 90 min under 1 sun irradiation. The promising photocatalytic activity of the composites was mainly attributed to excellent adsorption performance and light absorption capacity of the sample. Simultaneously, the recombination of photogenerated electron-hole pairs was delayed due to the formation of heterojunction between MnFe2O4 and g-C3N4, and MnFe2O4/g-C3N4 showed almost no decrease in photocatalytic activity after recycling for five times.

Significant Improvement of Photocatalytic Activity of TiO2/g–C3N4 Composite Synthesized by the Aiding of Hydrothermal Method

g–C3N4 nanosheets were first synthesized by calcining the mixture of hydrochloric acid-pretreated melamine and ammonium chloride. Then, by the aiding of solvothermal method and hydrofluoric acid as morphology modifier, 001-TiO2/g–C3N4 (TCN-X, [Formula: see text], 3, 2, 1) nanocomposites were synthesized using g–C3N4 nanosheets and tetrabutyl titanate, with the mass ratio of g–C3N4 to TiO2 was 5:1, 3:1, 2:1 and 1:1, respectively. The as-synthesized samples were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscopy, Fourier transform infrared spectroscopy, nitrogen adsorption–desorption method, ultraviolet–visible diffuse reflectance spectrum, photoluminescence spectrum, etc. Their photocatalytic properties were evaluated under visible light irradiation with rhodamine B (RhB) as the target pollutant. The results reveal that the TCN-3 composites had a large specific surface area of 67.38[Formula: see text]m2/g and consisted of g–C3N4 nanosheets and anatase TiO2 crystals about 10–20[Formula: see text]nm in size. The (001) crystal planes of TiO2 can be easily observed in TCN-X composites. All TiO2/g–C3N4 composites exhibited excellent photocatalytic activity compared with the pure g–C3N4 did. The photocatalytic property of TCN-X samples varied with the mass ratio of g–C3N4to TiO2, and TCN-3 presented the optimum photocatalytic performance. In total, 50[Formula: see text]mg of TCN-3 completely degraded 50[Formula: see text]mL and 100[Formula: see text]mL of RhB solution (10[Formula: see text]mg/L) in 15[Formula: see text]min and 40[Formula: see text]min, respectively. The reaction rate constant of TCN-3 was 6.7 times as large as that of pure g–C3N4. TCN-3 also presented outstanding activity for the photocatalytic degradation of the colorless tetracycline solution. The significant improvement in photocatalytic activity of TCN-3 was attributed to the evenly distribution of TiO2 on g–C3N4, the enhanced specific surface area and the construction of 001-TiO2/g–C3N4 heterojunction between the g–C3N4 nanosheets and the (001) crystal planes of anatase TiO2, which greatly reduced the recombination rate of the photo-generated electron and hole.

Synthesis of Ag/Bi2MoO6 composite nanosheets for enhanced photocatalytic degradation of RhB solution

Visible-light-driven photocatalyst Ag/Bi2MoO6 was successfully synthesized via a facile hydrothermal route. Ag was uniformly dispersed on the surface of Bi2MoO6 nanosheets. The photocatalytic performance of Ag/Bi2MoO6 composites was evaluated by the degradation of Rhodamine B (RhB). The Ag/Bi2MoO6 nanocomposite exhibited a higher photocatalytic activity as compared to pure Bi2MoO6. Moreover, the 7wt% Ag-loaded Bi2MoO6 showed the optimal photocatalytic performance in the degradation of RhB. The photogenerated holes (h+ ) and superoxide radical anions (•O 2- ) were found to be the primary reactive species in the degradation of RhB dye in aqueous solution.

Hydrothermal synthesis of TiO2/BiOBr composites with enhanced photocatalytic activity

The hydrothermal method is used to fabricate the TiO2/BiOBr composite. The X-ray diffraction, SEM, X-ray photoelectron spectroscopy, and ultraviolet-visible diffuse reflectance spectroscopy are employed to characterize its crystal structure, physical morphology, chemical composition, and light absorption. Its photocatalytic performance and stability are analyzed by the photocatalytic degradation rate of rhodamine B solution under sunlight irradiation. The composite exhibits the optimal photocatalytic effect when the Ti:Bi molar ratio is 4:1.

Facile Synthesis Bi2Te3 Based Nanocomposites: Strategies for Enhancing Charge Carrier Separation to Improve Photocatalytic Activity.

Varying structure Bi2Te3-based nanocomposite powders including pure Bi2Te3, Bi2Te3/Bi core−shell, and Bi2Te3/AgBiTe2 heterostructure were synthesized by hydrothermal synthesis using Bi2S3 as the template and hydrazine as the reductant. Successful realization of Bi2Te3-based nanostructures were concluded from XRD, FESEM, and TEM. In this work, the improvement in the performance of the rhodamine B (RhB) decomposition efficiency under visible light was discussed. The Bi2Te3/AgBiTe2 heterostructures revealed propitious photocatalytic performance ca. 90% after 60 min. The performance was over Bi2Te3/Bi core-shell nanostructures (ca. 40%) and more, exceeding pure Bi2Te3 (ca. 5%). The reason could be scrutinized in terms of the heterojunction structure, improving the interfacial contact between Bi2Te3 and AgBiTe2 and enabling retardation in the recombination rate of the photogenerated charge carriers. A credible mechanism of the charge transfer process in the Bi2Te3/AgBiTe2 heterostructures for the decomposition of an aqueous solution of RhB was also explicated. In addition, this work also investigated the stability and recyclability of a Bi2Te3/AgBiTe2 heterojunction nanostructure photocatalyst. In addition, this paper anticipates that the results possess broad potential in the photocatalysis field for the design of a visible light functional and reusable heterojunction nanostructure photocatalyst.

Fast decolorization of rhodamine-B dye using novel V2O5-rGO photocatalyst under solar irradiation

Degradation of dyes through Metal-oxide semiconductors using Advanced Oxidation Process (AOP) presents a unique opportunity for the development of advanced treatment techniques for effective removal of dyes from industrial wastewater. In this paper, an experimental study is being carried out by synthesizing the vanadium pentoxide–reduced graphene oxide (V2O5-rGO) nanocomposite for effective dye-degradation through photocatalysis under solar irradiation. V2O5-rGO nanocomposite is obtained by using an easy and efficient procedure of V2O5 nanowire in an rGO solution. V2O5 nanowires when bonded to rGO sheets (2D), serves as an excellent catalyst for the degradation of Rhodamine-B (RhB) dye. V2O5-rGO nanocomposites has been characterized using FESEM (Field Emission Scanning Electron Microscope), XRD (X-Ray Diffraction), and FTIR (Fourier Transform Infrared spectroscopy) techniques. V2O5-rGO is primarily used as a photocatalyst which utilizes sunlight for degradation of aqueous Rhodamine-B (RhB) dye through the principle of photoreaction. The nanocomposite shows ̴ 97% dye removal efficiency of RhB (20 mg/L) solution for a short processing time of 50 min. The study shows an increased generation of hydroxyl radicals (∙OH) in the presence of rGO sheets in the catalyst, which supports the photocatalytic process through suppression of electron (e-) and hole (h+) recombination causing the degradation of RhB dyes. Adding rGO shows ~84% faster decolorization in comparison to pure V2O5. The catalyst efficacy is further evaluated through varying pH of the RhB solution medium. A pH dependency of the reaction rate is observed with the fastest degradation time in the presence of V2O5-rGO nanocomposite being achieved at a pH of 9. Reusable catalytic properties for the suspended V2O5-rGO nanocomposite are studied for 6 cycles and the degradation efficiency of more than 90% is observed in 50 min. A brief study is performed to determine the decreased photocatalytic performance, which is fully reverted using simple chemical treatment by H2O2 and UV irradiation for further usage of the photocatalyst.

Environmental Remediation of Toxic Organic Pollutants Using Visible-Light-Activated Cu/La/CeO2/GO Nanocomposites.

Environmental pollution is a major threat that increases day by day due to various activities. A wide variety of organic pollutants enter the environment due to petrochemical activities. Organic contamination can be unsafe, oncogenic, and lethal. Due to environmental issues worldwide, scientists and research communities are focusing their research efforts on this area. For the removal of toxic organic pollutants from the environment, photocatalysis-assisted degradation processes have gained more attention than other advanced oxidation processes (AOPs). In this manuscript, we report a novel photocatalysis of copper and lanthanum incorporating cerium oxide (CeO2) loaded on graphene oxide (Cu/La/CeO2/GO) nanocomposites successfully synthesized by hydrothermal techniques. XRD results showed the presence of dopant ions and a crystalline structure. FESEM images showed that the surface morphology of the synthesized nanocomposites formed a rod-like structure. The highlight of this study is the in-situ synthesis of the novel Cu/La/CeO2/GO nanocomposites, which manifest higher photodegradation of harmful organic dyes (Rhodamine B (RhB), Sunset Yellow (SY), and Cibacron Red (CR)). In Cu/La/CeO2/GO nanocomposites, the dopant materials restrict the rapid recombination of photoinduced electron–hole pairs and enhance the photocatalytic activity. The degradation percentages of RhB, SY, and CR dye solution are 80%, 60%, and 95%, respectively. In summary, the synthesized nanocomposites degrade toxic organic dyes with the help of visible light and are suitable for future industrial applications.

Photocatalytic Mechanism Control and Study of Carrier Dynamics in CdS@C3N5 Core-Shell Nanowires.

We present a potential solution to the problem of extraction of photogenerated holes from CdS nanocrystals and nanowires. The nanosheet form of C3N5 is a low-band-gap (Eg = 2.03 eV), azo-linked graphenic carbon nitride framework formed by the polymerization of melem hydrazine (MHP). C3N5 nanosheets were either wrapped around CdS nanorods (NRs) following the synthesis of pristine chalcogenide or intercalated among them by an in situ synthesis protocol to form two kinds of heterostructures, CdS-MHP and CdS-MHPINS, respectively. CdS-MHP improved the photocatalytic degradation rate of 4-nitrophenol by nearly an order of magnitude in comparison to bare CdS NRs. CdS-MHP also enhanced the sunlight-driven photocatalytic activity of bare CdS NWs for the decolorization of rhodamine B (RhB) by a remarkable 300% through the improved extraction and utilization of photogenerated holes due to surface passivation. More interestingly, CdS-MHP provided reaction pathway control over RhB degradation. In the absence of scavengers, CdS-MHP degraded RhB through the N-deethylation pathway. When either hole scavenger or electron scavenger was added to the RhB solution, the photocatalytic activity of CdS-MHP remained mostly unchanged, while the degradation mechanism shifted to the chromophore cleavage (cycloreversion) pathway. We investigated the optoelectronic properties of CdS-C3N5 heterojunctions using density functional theory (DFT) simulations, finite difference time domain (FDTD) simulations, time-resolved terahertz spectroscopy (TRTS), and photoconductivity measurements. TRTS indicated high carrier mobilities >450 cm2 V-1 s-1 and carrier relaxation times >60 ps for CdS-MHP, while CdS-MHPINS exhibited much lower mobilities <150 cm2 V-1 s-1 and short carrier relaxation times <20 ps. Hysteresis in the photoconductive J-V characteristics of CdS NWs disappeared in CdS-MHP, confirming surface passivation. Dispersion-corrected DFT simulations indicated a delocalized HOMO and a LUMO localized on C3N5 in CdS-MHP. C3N5, with its extended π-conjugation and low band gap, can function as a shuttle to extract carriers and excitons in nanostructured heterojunctions, and enhance performance in optoelectronic devices. Our results demonstrate how carrier dynamics in core-shell heterostructures can be manipulated to achieve control over the reaction mechanism in photocatalysis.

Carbon nitride materials: impact of synthetic method on photocatalysis and immobilization for photocatalytic pollutant degradation

Different synthesis routes for carbon nitride materials (CN) and the resulting products were compared to study the photocatalytic activity (pollutant degradation) in dependence on structure and properties. The CN materials were synthesized by thermal decomposition of dicyandiamide in air and under argon as well as in sealed ampoules with or without the use of a salt melt. The as-prepared materials were characterized by IR spectroscopy, nitrogen adsorption measurement, solid-state NMR spectroscopy, diffuse reflectance UV–Vis spectroscopy, elemental analysis and powder X-ray diffraction (PXRD). The surface polarity of the CN materials was estimated by adsorption of the dicyano-bis(1,10-phenanthroline)-iron(II) complex, which allows an evaluation of the degree of condensation. The CN materials were tested with regard to the photocatalytic degradation of rhodamine B (RhB). It is shown that the photocatalytic activity increases with higher surface polarity. Promising CN materials with high RhB degradation of 85% within 25 min and high surface polarity of 0.89 were selected for an immobilization approach to obtain coatings on a silicone substrate using a high-volume low-pressure (HVLP) spray coating technique. To study the photocatalytic activity of the catalyst coatings, the degradation rates of an aqueous RhB solution and solutions of organic pollutants such as triclosan and ethinyl estradiol were examined. Pollutants are decomposed with up to 63% of the initial concentration. Xenon lamps and different LEDs were used as light sources for comparison. Particularly high degradation efficiencies were obtained using LEDs, and the degradation rates are increased by adjusting the emission spectrum of the lamp to the pollutant and absorption edge of the catalyst, which results in a 40 times higher degradation efficiencies of LEDs compared to a Xe lamp.Graphical abstract

A polyethersulfone composite ultrafiltration membrane with the in-situ generation of CdS nanoparticles for the effective removal of organic pollutants and photocatalytic self-cleaning

Ultrafiltration membranes are usually used to remove organic pollutants. However, the organic contaminants trapped in the membrane pores and on the membrane surface would limit the reuse of membranes. In this study, polyacrylic acid grafted polyethersulfone membrane was prepared; CdS was then generated in-situ on the membrane surface by subsequently immersing the membrane in Cd2+ and S2− solutions to fabricate photocatalytic composite membranes. Scanning electron microscopy and X-ray photonic energy spectroscopy revealed that the generated CdS were uniformly deposited on the surface of the membrane. The obtained membrane could effectively chemisorb rhodamine B (RhB) dye in dark, and show good photocatalytic degradation performance for RhB under visible irradiation. Meanwhile, the received membranes exhibited enhanced photocatalytic degradation performance compared with the membrane prepared by blending doping method, and displayed better removal performance (77.8 %) in the pH = 7 and low concentration (10 mg/L) RhB solution. Moreover, the degradation and removal ratio could still be stable at over 70 % after 3 cycles. In addition to degrading RhB, the composite membrane also exhibited good photocatalytic degradation for antibiotic organic pollutants. Then, free radical capture experiments showed that the photocatalytic degradation of the membrane was mainly derived from the superoxide anion free radicals. Besides, the prepared membrane also exhibited excellent RhB rejection and fast photocatalytic self-cleaning performances under visible light. Thereby, the photocatalytic composite membrane effectively solved the problem of the easy fouling of ultrafiltration membrane, and showed high potential applications in wastewater remediation.

Construction of 2D layered TiO2@MoS2 heterostructure for efficient adsorption and photodegradation of organic dyes

In this work, heterostructures of coupled TiO2@MoS2 with different phases of MoS2 were synthesized via hydrothermal technique. The prepared materials were thoroughly characterized using various techniques, including XRD, SEM, transmission electron microscopy, Brunauer–Emmet–Teller, XPS, Zeta potential and UV–vis spectroscopy. The optimized nanocomposites were tested for the photocatalytic degradation of methyl Orange (MO) under visible light as well as the adsorption of Rhodamine b (RhB) and methelene blue (MB) dyes. The TiO2@1T/2H-MoS2 heterostructures exhibited a narrow bandgap compared to the other studied nanomaterials. A remarkable photodegradation efficiency of TiO2@1T/2H-MoS2 was observed, which completely degraded 20 ppm of MO after 60 min with high stability over four successive cycles. This can be assigned to the formation of unique heterostructures with aligned energy bands between MoS2 nanosheets and TiO2 nanobelts. The formation of these novel interfaces promoted the electron transfer and increased the separation efficiency of carriers, resulting in high photocatalytic degradation. Furthermore, the adsorption efficiency of TiO2@1T/2H-MoS2 was unique, 20 ppm solutions of RhB and MB were removed after 1 and 2 min, respectively. The superior adsorption performance of the TiO2@1T/2H-MoS2 can be attributed to its high surface area (279.9 m2 g−1) and the rich concentration of active sites. The kinetics and the isothermal analysis revealed that the TiO2@1T/2H MoS2 heterstructures have maximum adsorption capacity of 1200 and 970 mg g−1 for RhB and MB, respectively. This study provides a powerful way for designing an effective photocatalyst and adsorbent TiO2-based nanocomposites for water remediation.

Investigation on g-C3N4/rGO/TiO2 nanocomposite with enhanced photocatalytic degradation performance

Three phase nanocomposites g-C3N4/rGO/TiO2 were synthesized successfully under hydrothermal reaction conditions using g-C3N4 nanosheets as matrix, as well as TiO2 sol and graphene oxide as the precursors of nano-size anatase and reduced graphene oxide (rGO), respectively. The photocatalytic performance of samples was investigated by degrading Rhodamine B (RhB) solution under sunlight irradiation with a xenon lamp. The results show that g-C3N4/rGO/TiO2 three-phase composite nanomaterial was successfully prepared. g-C3N4/rGO/TiO2 exhibited a satisfactory photocatalytic activity and cycle stability when the mass ratio of g-C3N4 nanosheets (0.6 g) to nano-TiO2 (0.2 g) was 3:1, the mass of GO was 0.002 g, the hydrothermal temperature and time were 160 °C and 6 h, respectively. When photocatalysis for 60 min, the degradation rate of RhB solution (100 mL, 10 mg/L) by g-C3N4/rGO/TiO2 (100 mg) reached 99.63%. Main reasons for these results lie in the significantly improved separation efficiency of photogenerated electron-hole pairs due to the construction of g-C3N4/TiO2 heterojunction, the enhanced optical absorption and the increased specific surface area.

Redox cycling of copper mediated by hydrazine: efficient catalyst systems for oxidative degradation of rhodamine B

Catalytic processes based on Fenton-like reactions on the degradation of organic pollutants have been improved by accelerating the redox cycling of metal ions. This work presents, at first, the results obtained for the heterogeneous degradation of rhodamine B (RhB) by copper ferrite (CuFe2O4) in presence of hydrogen peroxide (H2O2) and hydrazine (N2H4) as redox cycle accelerator. Atomic absorption spectroscopy showed small amounts of Cu2+ are leached from ferrite highlighting the influence of the homogeneous catalysis in the whole process. The data obtained for the homogeneous process using Cu2+ in solution containing both N2H4 and H2O2 indicated such system is highly efficient mineralizing 73% of RhB within only 10 min of reaction and having H2O and CO2 as major products. Using tert-butyl alcohol as radical scavenger, it was confirmed hydroxyl radical (HO•) is the active oxidant species regarding the RhB degradation. The homogeneous catalyst was applied to a real sample of textile effluent spiked with RhB and showed reasonable efficiency, although lower than that obtained for the standard solutions of RhB. This result was assigned to the interference of salts in the medium that react with HO• thus acting as radical scavenger.

Ag NPs decorated C–TiO2/Cd0.5Zn0.5S Z-scheme heterojunction for simultaneous RhB degradation and Cr(VI) reduction

In this study, heterojunction photocatalysts, XAg@C-TCZ, based on MOF-derived C–TiO2 and Cd0.5Zn0.5S decorated with Ag nanoparticles (Ag NPs) were successfully synthesized through hydrothermal and calcination methods. The catalytic effectiveness of XAg@C-TCZ was evaluated by simultaneous photocatalytic degradation of rhodamine B (RhB) and reduction of Cr(VI) under simulated sunlight irradiation. The presence of the Z-scheme heterojunction was demonstrated through trapping experiments, X-ray photoelectron spectroscopy (XPS), time-resolved photoluminescence (PL) investigations, and electron spin resonance (ESR) spectroscopy. With an initial RhB and Cr(VI) concentration of 7 mg L−1 and 5 mg L−1, the catalyst 10Ag@C-TCZ achieved a simultaneous removal of 95.2% and 95.5% within 120 min, respectively. With the same catalyst, the degradation rate of RhB was 2.75 times higher and the reduction rate of Cr(VI) was 9.3 times higher compared to pure Cd0.5Zn0.5S. Total organic carbon (TOC) analysis confirmed the extent of mineralization of RhB, while the reduction of Cr(VI) was corroborated by XPS. Compared to pure RhB and Cr(VI) solutions, the reaction rates are smaller in the solution containing both contaminants, which is attributed to the competition for ·O2−. 10Ag@C-TCZ also exhibited a stable catalytic performance in tap water and lake water. This work provides a new perspective on the construction of heterojunctions with doped MOF derivatives for the purification of complex pollutant systems.

Preparation of g-C3N4/diatomite composite with improved visible light photocatalytic activity

With the aid of mixing melamine and diatomite in hydrochloric acid aqueous solution, g-C3N4/diatomite (CN/DE-X, X = 2, 4, 6, 10, 14, which represented the mass ratio of melamine to diatomite) composites were synthesized by calcining the mixture at 550℃ for 2 h. Samples were characterized using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope, X-ray photoelectron spectroscopy, nitrogen adsorption–desorption measurement, ultraviolet–visible diffuse reflectance spectrum, and photoluminescence spectrum, etc. Rhodamine B (RhB) was used as trial pollutant to evaluate the photocatalytic activity of CN/DE-X composites. The results reveal that CN/DE-X composite is composed of g-C3N4 and diatomite. The photocatalytic activities of CN/DE-X composites are much better than that of pure g-C3N4 and varied with X. CN/DE-10 composite owns the best photocatalytic property in this study, which prohibited the agglomeration of g-C3N4 and had a specific surface area of 47.03 m2/g. 100 mg CN/DE-10 degraded more than 95% of RhB solution (10 mg/L, 100 mL) in 50 min, and its reaction rate constant was about 6.4 times that of pure g-C3N4. CN/DE-10 presents satisfactory stability and reusability since it degraded 90.01% of RhB molecules after 5 cycles of photocatalytic reaction. The outstanding photocatalytic performance of CN/DE-10 is attributed to the enhanced specific surface area, improved UV–Vis light absorption ability, narrowed band gap, reduced recombination rate of the photo-generated electrons and holes, which are brought about by the evenly anchoring of large amount of g-C3N4 on the surface of diatomite.

Significantly enhanced Fenton-based oxidation processes with CuS-Cu9S8 as co-catalyst by accelerating the Fe3+/Fe2+cycles

The co-catalyst plays an important role for improving the catalysis efficiency in Fenton system. In this paper, a new co-catalyst, CuS-Cu9S8 micro-flower was successfully prepared by a facilely hydrothermal method. The effect of co-catalysis for CuS-Cu9S8 micro-flower was evaluated by degradation of Rhodamine B (RhB) in Fenton system, and the RhB solution could be degraded 90% in 15 min in the CuS-Cu9S8 co-catalytic Fenton system under optimal condition, which is apparently better than that of the conventional Fenton system (59%). And EPR result shows that the unsaturated S atoms on the surface of CuS-Cu9S8 can capture protons to form H2S and expose more Cu+/Cu2+ active sites on the surface of CuS-Cu9S8 flower. The high co-catalytic activity of CuS-Cu9S8 on pollutant degradation can be attributed to the acceleration for the rate-limiting Fe2+/Fe3+conversion by the exposed Cu+ /Cu2+ redox pairs. The cycle experiments show that CuS-Cu9S8 has excellent chemical stability and reusability.

Efficient degradation of Rhodamine B by magnetically recoverable Fe3O4-modified ternary CoFeCu-layered double hydroxides via activating peroxymonosulfate

Environment-friendly nano-catalysts capable of activating peroxymonosulfate (PMS) have received increasing attention recently. Nevertheless, traditional nano-catalysts are generally well dispersed and difficult to be separated from reaction system, so it is particularly important to develop nano-catalysts with both good catalytic activity and excellent recycling efficiency. In this work, magnetically recoverable Fe3O4-modified ternary CoFeCu-layered double hydroxides (Fe3O4/CoFeCu-LDHs) was prepared by a simple co-precipitation method and initially applied to activate PMS for the degradation of Rhodamine B (RhB). X-ray diffraction (XRD), fourier transform infrared spectrometer (FT-IR), scanning electron microscope (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller method (BET), and vibrating sample magnetometer (VSM) were applied to characterize morphology, structure, specific surface area and magnetism. In addition, the effects of several key parameters were evaluated. The Fe3O4/CoFeCu-LDHs exhibited high catalytic activity, and RhB degradation efficiency could reach 100% within 20 min by adding 0.2 g/L of catalyst and 1 mmol/L of PMS into 50 mg/L of RhB solution under a wide pH condition (3.0-7.0). Notably, the Fe3O4/CoFeCu-LDHs showed good super-paramagnetism and excellent stability, which could be effectively and quickly recovered under magnetic condition, and the degradation efficiency after ten cycles could still maintain 98.95%. Both radicals quenching tests and electron spin resonance (ESR) identified both HO• and SO4•− were involved and SO4•− played a dominant role on the RhB degradation. Finally, the chemical states of the sample's surface elements were measured by X-ray photoelectron spectroscopy (XPS), and the possible activation mechanism in Fe3O4/CoFeCu-LDHs/PMS system was proposed according to comprehensive analysis.

Degreasing cotton used as pore-creating agent to prepare hydrophobic and porous carbon cathode for the electro-Fenton system: enhanced H2O2 generation and RhB degradation.

A porous carbon cathode was prepared using graphite, polytetrafluoroethylene (PTFE), and degreasing cotton (DC) through sintering treatment. The carbonization of DC by heat treatment played an ideal role in pore-creating, which weakened the mass transfer resistance of O2, and as a result, the adoption of degreasing cotton significantly improved the performance of H2O2 electro-generation. The optimized cathode was able to generate 567 mg L-1 H2O2 with a current efficiency (CE) of 86.7% by the electrochemical reaction of 60 min in a divided reactor. Furthermore, the degradation of rhodamine B (RhB) was carried out by an electro-Fenton system using the optimal cathode selected. The developed electro-Fenton system exhibited an excellent RhB degradation performance. The RhB solution of 50 mg L-1 was decolorized completely by the treatment of 10 min. Moreover, the degradation of 50~90 mg L-1 RhB solution presented over 90% TOC removal by the treatment of 120 min, indicating the ideal mineralization of organic pollutants. In addition, it was found that •OH was the major oxidizing specie responsible for the organics degradation. Finally, the possible pathway of RhB degradation in the electro-Fenton system was proposed by GC-MS analysis. The adoption of natural fibers for pore-creating provides an innovative and low-cost method to prepare porous cathode, which may promote the application of electro-Fenton oxidation in wastewater treatment.

Copper-promoted heterogeneous Fenton-like oxidation of Rhodamine B over Fe3O4 magnetic nanocatalysts at mild conditions.

Rhodamine B (RhB) is used in various industries and its effluent must be effectively treated because of its harmful and carcinogenic nature. In this work, ionothermally synthesized Cu-doped Fe3O4 magnetic nanoparticles (Cu-Fe3O4 MNPs) were found to be a highly efficient heterogeneous Fenton-like catalyst for complete decolorization of the RhB solution with H2O2 at pH ~ 7 and 25 °C. The effects of the catalyst loading, initial concentrations of RhB and H2O2, co-existing natural organic matter and inorganic salts, reaction temperature, and radical scavengers on the catalytic performance of Cu-Fe3O4 were investigated. Monte-Carlo simulations revealed that copper dopants facilitated the activation of H2O2 via adopting a terminal end-on adsorption mode and increased collision frequency by bringing the RhB molecules closer to H2O2 and the magnetite surface. These theoretical calculations provide new insight into the promotional effect of copper dopants in magnetite at molecular level.

The formation of uniform straw-like β-FeOOH nanostructures with superior catalytic performance for the degradation of Rhodamine B

In this work, uniform straw-like akaganeite (β-FeOOH) nanostructures with superior catalytic performance were successfully prepared via a facile hydrothermal method. The as-prepared uniform straw-like β-FeOOH nanostructures were characterized by various techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Visible (UV-vis) spectroscopy, UV-vis diffused reflection spectra (UV-vis DRS), and X-ray photoelectron spectroscopy (XPS). The optical property of β-FeOOH was investigated and the catalytic activity of β-FeOOH was also systematically evaluated in a Fenton process for the degradation of Rhodamine B (RhB). Based on the experimental results and analysis, it could be concluded that the as-prepared β-FeOOH nanostructures exhibited wide absorption wavelength range which was approximately 200–680 nm. The degradation efficiency of RhB reached 90% and the color of RhB solutions transformed from fresh pink to colorless after 9 h.