Blue Degradation Reaction Research Articles

Photocatalytic degradation of methylene blue using a Cu2+-modified bimetallic titanium-based metal organic framework (MIL-125) photocatalyst with enhanced visible light activity.

Cu-modified TiO2 nanoparticles derived from MIL-125 were prepared by solvothermal method for the photocatalytic degradation of methylene blue under visible light illumination. For boosting the photocatalytic performance as well as the physicochemical properties of bare sample, 2 wt % Cu2+ ions were integrated into the nodes of the MIL-125 framework. The results showed that incorporation of 2 wt % Cu2+ ions into the MOF framework had significant effects on the crystallographic structure and morphological and optical properties of photocatalytic samples, as well as catalytic activity for the methylene blue degradation reaction. The high activity profile of Cu-modified TiO2 nanoparticles derived from MIL-125 might be attributed to the increased thermal stability, lower band gap energy, and smaller crystallite size of the sample. Activity tests were carried out at five varying MB initial concentrations and four different pH values. According to the findings, an increase in initial dye concentration resulted in a decrease in degradation efficiency. It was observed that increasing the pH value in the range of 3-11 initially led to higher degradation rates until pH 7, after which the degradation rate began to decline.

Degradation of Anthraquinone dye wastewater by sodium percarbonate with CoO heterogeneous activation

AbstractBACKGROUNDAnthraquinone dyes have an anthraquinone structure as their nucleus, with one or more substituents forming different organic dyes. Anthraquinone dyes have a complex structure that allows them to exist stably in water environment, but also makes them more toxic than azo dyes. This results in varying degrees of harm to both humans and the environment as a result of residual dyes in the water or on the material’ surface. Sodium percarbonate (SPC) is a highly promising oxidant due to its green end product. Therefore, in this study, the catalytic performance and kinetic study of cobalt oxide (CoO) on SPC under different conditions were systematically investigated using RB19 as the target pollutant. The Box–Behnken Design (BBD) model was used to model the degradation of RB19 by CoO/SPC system, which gives the basis for practical application. The types of reactive oxygen species that effectively degrade RB19 and the potential degradation mechanism of the CoO/SPC system were revealed. At the same time, the CoO/SPC system was evaluated in terms of its practicality.RESULTSIn this work, the activation of SPC using CoO towards reactive blue 19 (RB19) degradation was explored. Experimental results showed that nearly 93.8% of RB19 could be removed within 30 min using 1 mmol L−1 SPC and 30 mg L−1 CoO. The three‐factor interaction effects of SPC concentration, CoO dosage and initial pH were investigated. The BBD model was set up to obtain the optimum working conditions of 1.039 mmol L−1 SPC, 33.35 mg L−1 CoO and the initial pH of 7.82, which gave a degradation rate of 95.372%. Additionally, it was confirmed that the solubility of Co2+ is consistently <150 μg L−1, meeting the emission standard (1 ppm). The presence of Cl−, NO3–, and HA had a similar profile, with a slight promoting effect in small amounts and an inhibitory effect when introduced in excess. The introduction of SO42– had a negligible effect on RB19 degradation, whereas the presence of HCO3− produced a slight inhibitory effect. Furthermore, the presence of PO43– showed a strong inhibitory effect. The CoO/SPC system is suitable for other organic dyes (32.7%–100%) and antibiotics (97.1–100%). Electron paramagnetic resonance (EPR) analysis and quenching experiments confirmed the presence and relative contribution of free radicals in the CoO/SPC system as CO3•‐ (88.12%) >O2•‐ (51.11%) >1O2 (37.21%) >•OH (5.27%) > SPC (3.33%) >CoO (0.09%). It has been confirmed that CoO activates SPC through electron transfer.CONCLUSIONThe present study describes a less time‐consuming, and more efficient method of treating anthraquinone dye wastewater that requires less oxidizer and catalyst, making it more economical. This proposes a straightforward, cost‐effective and efficient technique using SPC triggered by transition metal oxides. © 2024 Society of Chemical Industry (SCI).

Al/Ca-doped CuFe2O4 prepared from waste printed circuit boards as a magnetic peroxymonosulfate activator for the degradation of organic pollutants

Cu-containing heterogeneous catalysts are being increasingly used to activate peroxymonosulfate (PMS) and remove organic pollutants from wastewater. However, expensive raw materials and limited metal resources restrict the practical applications of these catalysts. In this study, waste printed circuit boards (PCBs), a typical Cu-rich electronic waste, were used to prepare Al/Ca-doped CuFe2O4 (PCBs-CuFe2O4) with the assistance of Fe3+. The obtained PCBs-CuFe2O4, doped with the catalytically inert metals Al and Ca, possessed abundant porous structures, high specific surface areas, rich surface oxygen vacancies, and excellent magnetic properties. Despite its relatively poor purity and crystallinity compared to those of CuFe2O4 prepared using commercial chemicals, PCBs-CuFe2O4 exhibited superior performance in reactive blue 19 (RB19) degradation by activating PMS. Additionally, the PCBs-CuFe2O4/PMS system exhibited strong resistance to pH and water matrices, confirming the practical application of PCBs-CuFe2O4 for the elimination of organic pollutants in wastewater. Furthermore, the results of electrochemical measurements, quenching experiments, and electron paramagnetic resonance analysis revealed that 1O2 plays an important role in the degradation of RB19. The Cu(I)/Cu(II), Fe(II)/Fe(III), and OV of PCBs-CuFe2O4 dominate the activation of PMS. Thus, this study presents a novel strategy for reutilizing waste PCBs and eliminating organic contaminants in wastewater.

Comparative study of metal nanoparticles anchored TiO2 using polyoxometalate intermediate in photodegradation of azo dye pollutant in aquatic environments

Herein, metal nanoparticles (Au, Ag, and Pt) are locally deposited on TiO2 with an UV-switchable polyoxometalate intermediate to achieve highly active photocatalyst nanohybrids. The successful preparation of these nanohybrids was confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Zeta potential (ZP), and UV–visible spectroscopy. TEM images showed the anchoring of metal nanoparticles of an average size of 20 nm on the TiO2 surface. A comparative study revealed that the bandgap energy was reduced in the order of Pt@PW-TiO2 (2.90 eV) > Ag@PW-TiO2 (2.95 eV) > Au@PW-TiO2 (3.05 eV). Likewise, the photocatalytic efficiency of fabricated nanohybrids was investigated in the degradation of reactive blue 19 (RB19), an azo dye model, under UV–visible light illumination and different experimental conditions. Optimal photodegradation occurred at pH = 3.8 with 0.33 gL−1 of photocatalyst exposed to light for 60 min. Under optimal conditions, the maximum and minimum photodegradation abilities were observed using Pt and Au deposited hybrids. A kinetic study of RB19 photodegradation was also conducted, resulting in pseudo-first order reaction rate constants of 0.0203, 0.025, and 0.0808 min−1, respectively, for the Au@PW-TiO2, Ag@PW-TiO2, and Pt@PW-TiO2 nanohybrids. Finally, the most probable mechanism for RB19 degradation using prepared photocatalysts is presented.

Electrochemical and photocatalytic properties of ZnO nanostructures deposited on nanoporous anodized aluminum oxide membrane and its application for degradation of reactive blue 19 in textile wastewater

The current study's objective was to develop a ZnO photocatalyst for the treatment of reactive blue 19 (RB19) from textile wastewater by depositing ZnO nanostructures over nanoporous anodized aluminum oxide (ZnO-AAO). The ZnO-AAO membrane was created using the atomic layer deposition (ALD) technique. SEM, XRD, and EDS morphological and structural characterizations demonstrated that ZnO nanostructures were successfully deposited on the AAO membrane. Studying the optical properties revealed that the band gap energies for ZnO, AAO, and ZnO-AAO membranes were found to be 3.19, 2.85, and 2.92 eV, respectively. This resulted in an improvement in the separation efficiency of photo-excited electrons and holes as well as an increase in the photocatalytic activity of the ZnO-AAO sample in the visible light region. Studying the electrochemical parameters revealed that ZnO-AAO had the lowest charge transfer resistance, which indicates that photoinduced electrons and holes in ZnO-AAO contacts effectively transfer charge and have slower recombination rates. According to research on photocatalytic performance, ZnO-AAO and ZnO photocatalysts required 70 and 90 min of visible light exposure to completely decolorize RB19, respectively. The photocatalytic decolorization of RB19 in an actual sample of textile wastewater showed that the dye could be effectively removed by photocatalytic means when ZnO-AAO membrane photocatalyst was present.

Preparation of magnetic nanoparticles as photo‒Fenton catalysts by a hydrothermal‒assisted thermal treatment method

The magnetic CoFe2O4 nanoparticles, prepared by hydrothermal method combining with the heat treatment at 600oC, were used to act as a photo‒Fenton catalyst in the methylene blue (MB) degradation reaction. The composition, structure, and surface morphology of the prepared materials were studied by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, field-emission scanning electron microscopy (FESEM), and energy-dispersive X-ray (EDX) spectroscopy. The optical properties of CoFe2O4 before and after calcination, analyzed by UV-Vis diffuse reflectance (DRS) spectroscopy, demonstrated that after heating at 600oC, the structure and crystallinity of CoFe2O4 were increased. The calcination process also caused the CoFe2O4 sintering to grow to a larger size, thereby reducing the surface area of the CoFe2O4 after calcination compared to the original ones. This value was determined through nitrogen the adsorption‒desorption isotherms curve. The magnetism of CoFe2O4 before and after calcination was studied by vibrating sample magnetometer (VSM). After sintering at 600oC, the saturation magnetization (Ms) and residual magnetism (Mr) of CoFe2O4 were higher than those of the original. The Fenton photocatalytic performance was evaluated by MB degradation reaction under UVA radiation in the presence of oxalic acid as an active free radical generating agent. In the methylene blue degradation reaction at room temperature, the prepared CoFe2O4 catalyst showed the maximum degradation efficiency of 97% for MB and the reaction yields were almost unchanged after three consecutive reactions. This method promised in making ferrite materials for water treatment based on some advantages such as simple process, low cost, and environmentally friendly solvent usage.

Enhanced photocatalytic degradation of reactive blue 19 using zeolitic imidazolate framework-8 composited with Fe3O4/MnO2 heterojunction

The present study offers a novel recyclable Fe3O4/MnO2/ZIF-8 heterojunction photocatalyst for the degradation of reactive blue 19 (RB19) under visible light irradiation. The catalyst was facilely synthesized by depositing Fe3O4/MnO2 nanocomposite onto the surface of ZIF-8 and characterized by field-emission scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, nitrogen adsorption–desorption isotherms and UV–vis spectroscopy. Morphology and structure characterization of the prepared photocatalyst indicated that polyhedral ZIF-8 (ca. 500 nm) was coated by MnO2/Fe3O4 nanorods. The synergy effect of Fe3O4/MnO2/ZIF-8 composite exhibited an excellent photocatalytic activity toward RB19 degradation of 99.5 % after 60 min of irradiation due to high surface area and heterojunction formation. According to scavenger tests, the photodegradation of RB19 dye over Fe3O4/MnO2/ZIF-8 was mainly contributed by OH and O2− reactive radicals. The kinetic study showed that the catalytic degradation of RB19 on Fe3O4/MnO2/ZIF-8 was better described by the first-order kinetic model. The new catalyst was easily recovered using an external magnetic field because of its magnetic properties. Besides, Fe3O4/MnO2/ZIF-8 showed high recyclability and stability, maintaining a high removal efficiency of 91.3 % even after ten repeated cycles. The overall results indicated that the fabricated composite can be used as an efficient photocatalyst for treating organic dyes in wastewater.

Effective utilization of CuO derived from waste printed circuit boards as a peroxymonosulfate activator for the degradation of reactive blue 19

Waste printed circuit boards (PCBs), a common electronic waste, contain a high content of Cu. For environmental sustainability and economic benefit, it is necessary to recover the Cu as high value-added product instead of discarding it. In this work, Cu from PCBs was successfully recovered as CuO particles with high specific surface area and rich oxygen vacancies through cyclic leaching, chemical precipitation, low temperature aging, and calcination. Compared with CuO prepared from commercial Cu(NO3)2·5H2O, the PCBs-derived CuO (PCBs-CuO) exhibited comparable performance in activating peroxymonosulfate to degrade reactive blue 19, although its crystallinity and phase purity were relatively lower. Additionally, PCBs-CuO had an outstanding pH tolerance (2–12), confirming the practical application potential of PCBs-CuO in the removal of organic contaminants in various wastewater. Moreover, the quenching experiments, electrochemical measurements and electron paramagnetic resonance analysis suggested that 1O2 and ·OH played a significant role in PCBs-CuO/peroxymonosulfate system. The ≡Cu(II) and oxygen vacancies on the surface of PCBs-CuO was mainly responsible for the activation of peroxymonosulfate. This work provides a promising method for recycling metal from waste PCBs into high-effective peroxymonosulfate activator and simultaneously achieving environmental remediation.

Waste eggshell-supported CuO used as heterogeneous catalyst for reactive blue 19 degradation through peroxymonosulfate activation (CuO/eggshell catalysts activate PMS to degrade reactive blue 19).

Advanced oxidation processes play an important role in the removal of organic pollutants from wastewater, in which it is essential to develop an eco-friendly, effective, stable, and inexpensive catalyst. Herein, waste eggshell-supported copper oxide (CuO/eggshell) was synthesized via a facile method and employed as peroxymonosulfate (PMS) activator for the elimination of reactive blue 19 (RB19). CuO/eggshell exhibited high degradation efficiency of RB19 (approximately 100%) by activation of PMS under the optimum conditions of 20 mg/L RB19, 0.2 g/L CuO/eggshell, 0.36 mM PMS, and initial pH 7.12 within 20 min. In addition, the effects of catalyst dosage, PMS concentration, initial pH, inorganic ions, and humic acid on RB19 degradation were investigated. Scavenging experiments and electron paramagnetic resonance revealed that multiple reactive oxygen species, including sulfate radicals (SO4·-), hydroxyl radicals (·OH), superoxide radicals (O2·-), and singlet oxygen (1O2), contributed to RB19 degradation, and 1O2 played a dominant role. Finally, a possible PMS activation mechanism was proposed. This study suggests that loading catalytically active components onto waste eggshell is eco-friendly and effective for enhancing the degradation of dyes from wastewater.

Enhanced photocatalytic activity and charge carrier separation of CNT/TiO2/WO3/CdS catalyst for the visible-light photodegradation of reactive blue 19.

The novel quaternary CNT/TiO2/WO3/CdS nanostructure was fabricated to be employed in the photocatalytic degradation of reactive blue 19 (RB19) under the visible light irradiation. The physicochemical properties of the pure TiO2, CNT/TiO2, CNT/TiO2/WO3, and CNT/TiO2/WO3/CdS were characterized using XRD, FTIR, FESEM, EDX, DRS, PL, and BET analyses. The photodegradation results showed that the optimum weight percentage of CNT, WO3, and CdS was 4%, 35%, and 5%, respectively. The highest RB19 degradation efficiency of CNT/TiO2/WO3/CdS was achieved 97%. Besides, the central composite design was applied to model and optimize the photocatalytic activity of CNT/TiO2/WO3/CdS nanocatalyst and assess the effects of processing variables including RB19 concentration, catalyst concentration, pH, and irradiation time on the response. RB19 concentration and pH had the most and the second most significant role in the removal efficiency. While increasing the catalyst concentration and irradiation time positively enhanced the removal efficiency to more than 82%, increasing the pH and dye concentration showed the remarkable hindering effects on the removal efficiency by about 45% reduction. The reusability of the synthesized catalysts was studied under the optimum conditions as follows: [RB19] = 25mg/L, [catalyst] = 1g/L, pH of 4, and irradiation time = 2h. The COD and TOC analyses were also conducted during photodegradation process. The COD and TOC removal efficiencies were achieved about 67% and 62%, respectively.

Photocatalytic performance under visible light of WS2/TiO2/Au synthesized by hydrothermal method

In this study, transition metal dichalcogenide (TMD) material WS2 and Au nanoparticles were combined with TiO2 to enhance the photocatalytic performance under visible light. The WS2 nanosheets were synthesized from bulk WS2 via ultrasonic process, and the Au nanoparticles were prepared through the reduction reaction from HAuCl4. The composite photocatalysts of WS2/TiO2/Au, TiO2/Au, and WS2/TiO2 were synthesized by a one-step hydrothermal process. The light absorption property of the composites was determined by ultraviolet-visible (UV-vis) photospectroscopy. Surface analysis of WS2 nanosheet, TiO2 nanoparticles, and Au nanoparticles was performed by scanning electron microscopy (SEM). The chemical structure of composites and thickness of WS2 nanosheets were analyzed by Raman spectra. The photocatalytic activity was measured by methylene blue degradation reaction under visible light. These results revealed the photocatalytic behavior of WS2/TiO2/Au, TiO2/Au, and WS2/TiO2 composites, as well as WS2 nanosheets. The WS2/TiO2/Au composite showed improved photocatalytic behavior among all samples. It is believed that the WS2 nanosheet and Au nanoparticle extend the light absorption range from UV region to the visible region, as well as the WS2/TiO2/Au composite reduces the recombination of electrons. This study shows that the enhanced photocatalytic behavior of WS2/TiO2/Au composite can be used as photocatalytic applications in the future.

Z-scheme heterojunction of Bi2S3/g-C3N4 and its photocatalytic effect

In this study, Bi2S3/g-C3N4 binary catalyst has been excellently prepared by a wet impregnation-calcination method to form Z-scheme heterojunction. The catalyst has been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible diffuse reflectance spectroscopy (UV-DRS) and photoluminescence spectroscopy (PL). The physicochemical properties of the catalyst have been tested, such as crystal structure, morphology, optical properities, light absorption properties and luminescence properties. The results demonstrate that the photocatalytic activity is significantly increased when Bi2S3 with optimum weight percentage (5wt%) loaded into g-C3N4. Through photocatalytic degradation experiments, the optimal loading ratio, dosage and dye concentration of binary materials have been explored. At the same time, the effect of pH on the photocatalytic experiment under the optimal conditions is studied. Reactive blue 19 (RB19) is degraded by 97.77% in 2 h as the target pollutants. The trapping experiment further verified that ꞏO2 - is the main active species in photocatalytic degradation of RB19.

The optical and photo-electrochemical characterization of nano-ZnO particles and its application to degradation of Reactive Blue 19 under solar light

To assess its photocatalytic activity under sunlight, ZnO nano powder with crystallites sizes in the range (18–29 nm) was synthesized by decomposition from nitrate (ZnO-Nit) and acetate (ZnO-Ac) precursors by one-step calcinations. The powders were characterized by X-ray diffraction, transmission electron microscopy and Fourier-transform infrared spectroscopy. The optical band gap of ZnO-Ac, determined from the diffuse reflectance, was found to be 3.23 eV and the transition is directly allowed, due to the charge transfer O2−: 2p → Zn2+: 4s. The capacitance-potential (C−2 – E) characteristic plotted at pH ∼7 shows n type behaviour with a conductionband (−0.42 VSCE), made up of Zn2+: 4s orbital and positive of the O2/O2 level and a valence band (2.81 VSCE) deriving mostly from O2−: 2p orbital whose potential is less anodic than the OH/H2O level. So, ZnO was successfully used for the degradation of the Reactive Blue 19 (RB 19) a hazardous dye, by both radicals O2−and OH under solar light. Indeed, RB 19 is a vinylsulphone dye, difficult to eliminate by chemical oxidation because its anthraquinone structure is highly stabilized by resonance. The best photoactivity occurs over ZnO-Ac owing to its large active surface area (59 m2 g−1). The oxidation obeys a zero order kinetic with a rate constant of 7.3 × 10−3 mol L−1 min−1. The elaborated material showed an outstanding recyclability.

Low cost effective heterogeneous photo-Fenton catalyst from drinking water treatment residuals for reactive blue 19 degradation: Preparation and characterization.

Four different catalysts from drinking water treatment residuals (DWTR) were prepared via impregnation in the iron nitrate, calcined at different temperatures ranged from 200°C to 500°C, and tested for the reactive blue 19 oxidation using the heterogeneous photo-Fenton, under UVA light source. XRD and XPS results revealed that iron nature was found under a ferric oxide form (Fe3+ ) similar to the magnetite. Calcination temperature results showed a significant effect on the activity of the catalysts. RB19 and TOC removals were 99% and 79%, respectively, with the best catalyst that calcined at 500°C in optimal conditions as follows: initial pH solution=3, 10mM of H2 O2 dosage, 0.5g/L of catalyst loading, reaction temperature 35°C, and IUVA =3.55MW/cm2 for 50mg/L of RB19. The reusability of the catalyst after three cycles showed complete removal of RB19 and 65% TOC removal. PRACTITIONER POINTS: Synthetized heterogeneous photo-Fenton catalyst from drinking water treatment residuals for the photo Fenton oxidation. The calcination temperatures plays a crucial role in catalyst photocatalytic activity. Degradation of reactive blue 19 with Fe/DWTR-500 in presence of H2 O2 . The Fe/DWTR-500 catalyst exhibited the best photocatalytic activity. Reusability studies of Fe/DWTR-500 and the kinetics of reactive blue 19 degradation were investigated.

Degradation of Reactive Blue 19 (RB19) by a Green Process Based on Peroxymonocarbonate Oxidation System.

The effectiveness of peroxymonocarbonate (HCO4−) on the degradation of Reactive Blue 19 (RB19) textile dye was investigated in this study. The formation kinetics of HCO4− produced in situ in a H2O2 − HCO3− system was studied to control the experimental conditions for the investigation of RB19 degradation at mild conditions. The effects of metallic ion catalysts, the pH, the input HCO3− and Co2+ concentrations, and UV irradiation were studied. The obtained result showed that Co2+ ion gave the highest efficiency on accelerating the rate of RB19 degradation by the H2O2–HCO3− system. In the pH range of 7–10, the higher pH values resulted in faster dye degradation. The reaction orders of the RB19 degradation with respect to Co2+ and HCO3– were determined to be 1.2 and 1.7, respectively. The UV irradiation remarkably enhanced the radical formation in the oxidation system, which led to high degradation efficiencies. The COD, TOC removal, and HPLC results clearly revealed complete mineralization of RB19 by the H2O2 − HCO3−−Co2+ system.

Simultaneous utilization of electro-generated O2 and H2 for H2O2 production: An upgrade of the Pd-catalytic electro-Fenton process for pollutants degradation

• Pd/Activated carbon/stainless steel mesh (PACSS) hybrid cathode was fabricated. • H 2 and O 2 from water electrolysis were both utilized by PACSS cathode for H 2 O 2 generation. • PACSS cathode can support effective H 2 O 2 generation and activation simultaneously. • The novel process is more effective for pollutants degradation than Pd-catalytic EF process. The Electro-Fenton (EF) process is one of the promising advanced oxidation processes (AOPs) for environmental remediation. The H 2 O 2 yield of EF process largely determines its performance on organic pollutants degradation. Conventional Pd-catalytic EF process generates H 2 O 2 via the combination reaction of anodic O 2 and cathodic H 2 . However, the relatively expensive catalyst limits its application. Herein, a hybrid Pd/activated carbon (Pd/AC)-stainless steel mesh (SS) cathode (PACSS) was proposed, which enables more efficient H 2 O 2 generation. It utilizes AC, the support of Pd catalyst, as part of cathode for H 2 O 2 generation via 2-electron anodic O 2 reduction, and SS serve as a current distributor. Moreover, H 2 O 2 could be catalytically decomposed upon AC to generate highly reactive OH, which avoids the use of Fe 2+ . Compared with conventional Pd catalyst, H 2 O 2 concentration obtained by PACSS cathode is 248.2% higher, the O 2 utilization efficiency was also increased from 3.2% to 10.8%. Within 50 min, 26.3%, 72.5%, and 94.0% H 2 O 2 was decomposed by Pd, AC, and Pd/AC. Fluorescence detection results implied that Pd/AC is effective upon H 2 O 2 activation for OH generation. Finally, iron-free EF process enabled by PACSS cathode was examined to be effective for reactive blue 19 (RB19) degradation. After continuous running for 10 cycles (500 min), the PACSS cathode was still stable for H 2 O 2 generation, H 2 O 2 activation, and RB19 degradation, showing its potential application for organic pollutants degradation without increase in the running cost.

CoFe2O4@Methylcelloluse as a New Magnetic Nano Biocomposite for Sonocatalytic Degradation of Reactive Blue 19

Reactive Blue 19 (RB19) removal from synthetic textile wastewater was investigated by using a CoFe2O4@methylcellulose (MC) activated with peroxymonosulfate (PMS) and the ultrasound process. CoFe2O4@MC as a new magnetic nano-biocomposite was prepared using a convenient and rapid microwave-assisted technique in presence of MC as a green biopolymer, and characterized by FESEM, EDS, Mapping, TEM, FTIR, XRD, TGA, VSM, and BET techniques. Then, the effective parameters including pH (4–10), reaction time (0–30 min), CoFe2O4@MC (0.2–1 g/L), and PMS concentration (0.5–10 mM) in the sonocatalytic degradation of RB19 were investigated. The maximum removal efficiency of RB19 was achieved as 97% for synthetic wastewater under the optimal conditions of pH 4, CoFe2O4@MC dosage (0.6 g/L), reaction time = 30 min, and PMS (5 mM) in the presence of ultrasonic waves (60 kHz) at the ambient room temperature of 22 °C. The CoFe2O4@MC catalyst was simply isolated using a magnet and recycled with no remarkable loss of catalytic activity following usage in four runs. The results showed that the CoFe2O4@MC sonocatalysis process is practical, and effective for degrading complex and resistant dyes such as RB19.

Catalytic performance of boron-containing magnetic metal nanoparticles in methylene blue degradation reaction and mixture with other pollutants

The catalytic effects of metal nanoparticles (MNPs) synthesized in sodium bis(2-ethylhexyl) sulfosuccinate (AOT) microemulsion system by using M(II) salts (M = Fe, Co, Ni) and NaBH4 reducing agent on methylene blue (MB) degradation reaction were investigated. It was determined that Co-MNPs gave the best catalytic activity among them. Influence of the reaction parameters e.g., reaction time, temperature, the size of catalyst and the MNP types on the catalytic performance were studied. It was found that 37 ± 6 nm Co-MNPs revealed the best catalytic activity in all studies. The best activation parameters were calculated as 13.6 ± 1.1 kJ mol−1 and ΔH = 10.7 ± 1.0 kJ mol−1 and ΔS = -87.9 ± 5.4 J mol−1 K−1. The activity % of Co-MNPs was calculated as 85.4 after 30 days on the shelf life study. The reusability studies were carried out and the activity of Co-MNPs at the 5th reuse was calculated as 70 ± 5%. Finally, the catalytic activity of Co-MNPs was investigated inside equal volumes of single and multiple solution mixtures containing MB, 4-Nitrophenol (4-NP) and Eosin Y (EY). In the examinations, it was observed that the nanocatalyst was effective as a reducing agent in all equal amount solutions (MB/4-NP, MB/EY, 4-NP/EY, and MB/4-NP/EY). And also, TOF (mole of MB/4-NP/EY) (mol catalyst.min)−1 values ​​of catalytic activities were also calculated.

Degradation of anthraquinone dye reactive blue 19 using persulfate activated with Fe/Mn modified biochar: Radical/non-radical mechanisms and fixed-bed reactor study

In this study, a heterogeneous activator was prepared via the Fe/Mn modification of sludge-derived biochar (Fe/MnBC) to achieve high-efficiency activation of persulfate (PS) for reactive blue 19 (RB19) degradation. The morphologies and chemical states of Fe/MnBC were examined by various characterizations. A comprehensive assessment was conducted to reveal the effects of biochar preparation conditions and system reaction conditions. According to the results of scavenger quenching experiments and electron paramagnetic resonance (EPR) testing, the mechanisms of Fe/MnBC combined PS system on RB19 degradation were proposed, including radical and non-radical mechanisms. The formation and involvement of sulfate radical (SO4·−), hydroxyl radical (OH·), and singlet oxygen (1O2) were proved in this system, and Fe(IV)/Mn(VII) was also speculated to participate in the non-radical degradation process. These findings give a new insight into the mechanisms of PS activated by metal-biochar composite. Besides, fixed-bed reactor (FBR) experiments indicated that the Fe/MnBC has considerable PS activation potential for dyes removal. The degradation process was further modeled by the central composite design (CCD-RSM) and artificial neural networks (ANN) methods. The statistical metrics and prediction indicated that the prediction results of ANN model were better than CCD-RSM model, and the ANN model could perfectly predict the reaction process of Fe/MnBC FBR for engineering applications.

Mg0.5NixZn0.5-xFe2O4 spinel as a sustainable magnetic nano-photocatalyst with dopant driven band shifting and reduced recombination for visible and solar degradation of Reactive Blue-19

Focussing on visible light active ferrites for high performance removal of noxious pollutants, we report the synthesis of Mg0.5NixZn0.5-xFe2O4 (x = 0.1, 0.2, 0.3, 0.4, & 0.5) ferrite nanoparticle for degradation of reactive blue-19 (RB-19). Lattice parameters calculated using intense X-ray diffraction (XRD) peaks and Nelson-Riley plots (N-R plot) are in well agreement with each other. The sample Mg0.5Ni0.4Zn0.1Fe2O4 (M5N4) exhibits best performance with 99.5% RB-19 degradation in 90 min under visible light. Photoluminescence (PL) results confirm that recombination of charge carriers is highly reduced in the photocatalyst. Scavenging experiments suggest that O2− radicals were the dominant species responsible for photocatalytic performance. The photocatalytic mechanism was explained in terms of dopant driven shifting of conduction bands and valence bands (calculated by Mott-Schottky plots). The thermodynamic probability of radical generation along with role of redox cycles of metal ions has been discussed in the mechanism. The dye degradation was ascertained by detection of intermediates via mass spectrometry analysis and a possible degradation route was also predicted. The findings in this work provide intriguing opportunities to modify the electronic band structure of spinel ferrites for visible and solar light photocatalytic activity for environmental detoxification.