Elimination Of Methylene Blue Research Articles

Methylene blue (MB) removal from aqueous solution by alum; catalytic ozonation process

Textile wastewater is among the most polluted types of industrial waste. Wastewater treatment in the textile industry is notoriously difficult because of the use of complex chemicals and dyes in the textile production steps, and conventional methods are not enough to treat these. Textile wastewater, known for its high pollution levels, poses challenges for treatment due to complex chemicals and dyes. A comparative study was conducted on simple ozonation and catalytic ozonation (CO) using alum to degrade methylene blue (MB). The authors analyzed various factors like time, pH, catalyst loading and ozone dosages during the study. Results showed that catalytic activity in ozonation depends on pH and ozone flow. The maximum MB elimination was achieved at pH 6.6 and 200 V ozone flow. Scanning electron microscopy (SEM) was used to characterize the surface morphology of the catalyst, Fourier transform infrared spectroscopy (FTIR) was used to identify the important functional groups, and energy dispersive X-ray spectroscopy (EDS) was used to characterize the catalyst's elemental composition. Compared to simple ozonation, CO showed higher removal in the initial phase. Real textile wastewater analysis confirmed the effectiveness of alum catalysts in achieving significant removal of MB (87%) through this novel cost-efficient process.Graphical

Ce-TiO2 nanoparticles with surface-confined Ce3+/Ce4+ redox pairs for rapid sunlight-driven elimination of organic contaminants from water

Industrial discharge of organic pollutants poses a severe threat to human health and aquatic life. Elimination of these pollutants from drinking and wastewater is imperative for a sustainable environment. To address this issue, pure and Ce3+-doped TiO2 nanoparticles are designed with stable tetragonal (anatase) lattices by a low-temperature sol–gel process. The spectroscopic and structural analyses reveal the formation of TiO2 and Ce-TiO2 nanocrystals with controlled crystallite size (3–6 nm), high surface areas, and varying surface chemistry. The effect of calcination (thermal (Δ) treatment at 450 °C) on the structure and photocatalytic performance of ΔTiO2 and ΔCe-TiO2 nanoparticles is also investigated. Simultaneous photocatalysis experiments over a 90-min exposure to natural sunlight show 240 % and 191 % improved elimination of methylene blue (MB), an organic pollutant, by Ce-TiO2 and ΔCe-TiO2 nanoparticles compared to their pure TiO2 analogs. Also, Ce-TiO2 and ΔCe-TiO2 nanoparticles exhibit 326 % and 229 % faster kinetics for the photocatalytic elimination of MB primarily due to the surface-confinement of Ce3+ in Ce-TiO2 nanocrystals, where Ce3+ ions play a dual role as reducing agent for adsorbed oxygen species and electron trap sites via Ce3+/Ce4+ interconversion. The mechanism of photocatalytic redox reactions is discussed. The study elaborates on the role of Ce-TiO2 nanoparticles as an effective photocatalyst for the elimination of organic pollutants in wastewater.

Carbide lime as substrates to boost energy recuperation and dyestuff removal in constructed wetland-microbial fuel cell integrated with copper oxide/carbon cloth cathode.

Methylene blue (MB) was regarded as a highly toxic and hazardous substance owing to its irreparable hazard and deplorable damage on the ecosystem and the human body. The treatment of this colorant wastewater appeared to be one of the towering challenges in wastewater treatment. In this study, a microbial fuel cell coupled with constructed wetland (CW-MFC) with effective MB elimination and its energy recuperation concurrently based on the incorporation of carbide lime as a substrate in a new copper oxide-loaded on carbon cloth (CuO/CC) cathode system was studied. The crucial influencing parameters were also delved, and the MB degradation and chemical oxygen demand (COD) removal efficiencies were correspondingly incremented by 97.3% and 89.1% with maximum power output up to 74.1 mW m-2 at optimal conditions (0.2 g L-1 carbide lime loading and 500 Ω external resistance). The carbide lime with high calcium ion content was greatly conducive for the enrichment of critical microorganism and metabolic activities. The relative abundances of functional bacteria including Proteobacteria and Actinobacteriota were vividly increased. Moreover, the impressive results obtained in printed ink wastewater treatment with a COD removal efficiency of 81.3% and a maximum power density of 58.2 mW m-2, which showcased the potential application of CW-MFC.

A novel porous layered K2Ti8O17 for capturing MB and Cu(Ⅱ) in wastewater

Appropriate structural design engineering is an effective method to achieve high adsorption performance, and optimizing the architecture to meet the desired properties remains challenging for adsorbents. Herein, a novel porous layered K2Ti8O17 (PLKTO) formed by interweaved nanowires has been successfully synthesized using MAX phase Ti2AlN and g-C3N4 as the precursors. The K2Ti8O17 nanowires consisted of numerous interconnected pores in a network-like distribution configuration, with a diameter of approximately 20 nm and a length exceeding one μm. Attractively, the PLKTO exhibited fast kinetics, large adsorption capacity, and excellent reusability toward methylene blue (MB) and Cu2+ adsorption. The maximum equilibrium adsorption capacity of MB and Cu2+ was 95.00 mg/g and 330.75 mg/g, with equilibrium times of ∼18 min and ∼25 min, respectively. The adsorption mechanism unveiled that the elimination of MB and Cu2+ was dominated by the pore-filling effect, electrostatic interaction, hydrogen bond, and surface complexation. Additionally, the PLKTO enjoyed highly selective for Cu2+ while investigating competitive adsorption behaviors in binary systems and real-world applications in various water matrices. These results indicated that the PLKTO revealed appealing application prospects for treating wastewater and pollutants and provided methodological guidance for design engineering in fabricating porous and layered structures.

Synergistic Effect of Selenium Dioxide for Better Photocatalytic Performance of Conventional Semiconductors Distributed into Mesoporous SBA‐15

AbstractThe mesoporous SBA‐15 was synthesized in acidic conditions by hydrothermal method using Pluronic surfactant P123. A combination of SeO2, TiO2, and CuO was loaded in SBA‐15 in pairs or singly. Synthesized SBA‐15 and some loaded mesoporous materials were characterized using several standard techniques. The efficiency of the synthesized photocatalysts was verified for the decomposition of two different dyes (methylene blue (MB) and methyl green (MG)) under ultraviolet and visible light radiation. The results show that the synthesized photocatalyst based on SBA‐15 with 5 % by weight of TiO2 and 5 % by weight of SeO2 has better performance (about 98 % of MB or MG were degraded within 120 min under UV radiation). Also, the photocatalyst with 5 % by weight of SeO2 and 5 % by weight of CuO shows a good performance for the degradation of the dyes under visible irradiation in the presence of H2O2 (complete elimination of MB and MG within 150 and 75 min, respectively). The scavenging test shows that superoxide has a governing role for the degradation of the dyes. The photocatalysts are reusable and they could preserve more than 74 % of the efficiency following 4 times of consecutive use for the degradation of the dyes.

Green synthesis of ZnO and Co-ZnO using Brassica rapa leave’s extract and their activities as antioxidant agents, efficient adsorbents, and dye removal agents

The wastewater released from industries contains many harmful materials like organic dyes and toxic metal ions which badly affect our environment. Nanotechnology is one of the unique approaches to reducing these chemicals. In current research work monometallic ZnO and Co-ZnO bimetallic NPs were synthesized from Brassica rapa leave’s extract and then these were employed for the elimination of methylene blue (MB) and metal ions of Cu (II). Characterization was done by several analytical techniques such as EDX, FTIR, UV–Visible spectroscopy, SEM and XRD. The average diameter of ZnO and Co-ZnO BMNPs was found to be 32.94 nm and 13.82 nm assessed by XRD analysis. The SEM investigation revealed that the produced NPs had a spherical shape. Three distinct methods have opted to determine the antioxidant potential of synthesized NPs. Different factors like pH, contact time, NPs conc., dye conc. and temperature were studied for the elimination of dye while for the eradication of Cu (II) ions; pH, contact time, NPs conc. and adsorbate doses were studied. Adsorption isotherm and kinetic studies were employed for MB and Cu (II) ions elimination while thermodynamic studies were also done for the elimination of MB.

Banana Peel Powder Biosorbent for Removal of Hazardous Organic Pollutants from Wastewater.

Disposing of pollutants in water sources poses risks to human health and the environment, but biosorption has emerged as an eco-friendly, cost-effective, and green alternative for wastewater treatment. This work shows the ability of banana peel powder (BPP) biosorbents for efficient sorption of methylene blue (MB), atrazine, and glyphosate pollutants. The biosorbent highlights several surface chemical functional groups and morphologies containing agglomerated microsized particles and microporous structures. BPP showed a 66% elimination of MB in 60 min, with an adsorption capacity (qe) of ~33 mg g-1, and a combination of film diffusion and chemisorption governed the sorption process. The biosorbent removed 91% and 97% of atrazine and glyphosate pesticides after 120 min, with qe of 3.26 and 3.02 mg g-1, respectively. The glyphosate and atrazine uptake best followed the Elovich and the pseudo-first-order kinetic, respectively, revealing different sorption mechanisms. Our results suggest that BPP is a low-cost biomaterial for green and environmentally friendly wastewater treatment.

In‐situ synthesis of reduced graphene oxide templated MIL‐53(Fe) nanorods for photo‐catalytic degradation of organic dyes under sunlight

AbstractDue to outstanding chemical and physical characteristics, metal‐organic‐frameworks (MOFs) are frequently apprenticed for environmental clean‐up. Within this article, we present a thorough and straightforward hydrothermal method towards the production of reduced graphene oxide templated MIL‐53(Fe) hybrids RGO@MIL‐53(Fe). The structural characteristics of created hybrids were identified by using BET, FESEM, powder X‐ray diffraction, and FTIR techniques. Methylene blue (MB) dye (a model water pollutant) was used to evaluate H2O2‐assisted photo‐catalytic efficiency of RGO@MIL‐53(Fe). In contrast to pristine MIL‐53(Fe)‐H2O2, the RGO@MIL‐53(Fe)‐H2O2 system demonstrated improved photodegradation efficiency (>99%) for the elimination of MB over 60 minutes of solar irradiation. Furthermore, another dye rhodamine B (RhB) was almost 100% degraded in similar conditions within 80 minutes of sunlight. The RGO@MIL‐53(Fe) hetero‐structure, which promotes quick electron transport and reduces the rate at which photo‐induced charge carriers recombine, is credited as the main cause of the improvement in photo‐catalytic efficiency.

Methylene blue elimination by magnetic ferric oxide-decorated and sulfonated sugarcane bagasse-derived porous carbon via catalysis Fenton reaction

In this study, the magnetic ferric oxide-sulfonated porous carbon materials (Fe3O4-SPC) were fabricated using the magnetic ferric oxide (Fe3O4) nanoparticles via the sulfonation process with sugarcane bagasse as a main cellulose source. The characterization revealed that the spherical shape of Fe3O4 nanoparticles decorated on lamellar porous carbon sheet with uniform size less than 100 nm. Meanwhile, the catalytic assessment on the degradation of methylene blue via the Fenton reaction showed the ratio of Fe3O4:SPC = 1:2 obtaining the efficiency of 95% after 45 min. Moreover, the material had high reusability, retaining over 95% after 5 consecutive cycles.

Adsorption mechanism and synthesis of adjustable hollow hydroxyapatite spheres for efficient wastewater cationic dyes adsorption

The efficient adsorption of toxic dyes has been an important issue in water pollution control. Nowadays, researchers are experimenting with various methodologies to determine the optimal conditions for synthesizing hydroxyapatite (HAP) particles with a fine, hollow morphology, which has been a major difficulty in the field of study. In this research work, controlled hollow mesoporous HAP particles were successfully prepared using a CaCO3 core as a template at various hydrothermal reaction times. It was noted that by adjusting the hydrothermal process, the hollow morphology of the HAP particles could be regulated, with the best hollow mesoporous hydroxyapatite (HM-HAP) particles formed at the 6 h reaction period. Adsorption characteristics were determined via the adsorption of cationic dyes (methylene blue and methyl violet) onto synthesized HM-HAP particles. Langmuir’s adsorption isotherm was the best fit for describing the adsorption of methylene blue (MB) and methyl violet (MV) (R2 = 0.99 and 0.98), indicating monolayer adsorption. For kinetic studies, the adsorption of MB and MV fits well with the pseudo-second-order model (R2 = 0.99), demonstrating the chemisorption process. The maximal uptake capacities determined using the Langmuir model were 143 mg/g and 453 mg/g for MB and MV, respectively. According to the results of the sorption-desorption experiment, it was possible to renew and reuse synthesized HM-HAP for a maximum of four cycles. Therefore, the HM-HAP particles synthesized in this study were demonstrated to be effective adsorbents for the elimination of MB and MV in aqueous solutions.

Single/co-adsorption and mechanism of methylene blue and lead by β-cyclodextrin modified magnetic alginate/biochar

Due to the high biological toxicity, the concurrent elimination of lead (Pb (II)) and methylene blue (MB) has become a challenging problem. Therefore, a newly β-cyclodextrin (β-CD) modified magnetic alginate/biochar (β-CD@MBCP) material was developed. Comprehensive characterizations proved the successful coating of β-CD onto MBCP surface by microwave-aided fabrication. The β-CD@MBCP achieved high-efficiency uptake for contaminants under a wide pH scope. In the dual system, Pb (II) elimination was facilitated with the presence of MB, due to the active sites provided by MB. In the presence of Pb (II), MB uptake was inhibited due to the electrostatic repulsion between positively charged MB and Pb (II). Electrostatic attraction and complexation contributed to capturing Pb (II), while π-π interactions, host–guest effect, and H-bonding were important in MB elimination. After four cycles, β-CD@MBCP maintained comparatively good renewability. Findings demonstrated that β-CD@MBCP could be an effective remediation material for Pb (II)/MB adsorption from aqueous environments.

Mechanisms of dyes adsorption on titanium oxide– graphene oxide nanocomposites

Graphene oxides (GOs), synthesized with different oxidation degrees and associated with Titanium dioxide (TiO2) nanoparticles show efficient adsorption processes for dye molecules in solution. The structural, morphology, electronic and optical features of the nanocomposites were investigated by dedicated methods. Water remediation was investigated through the adsorption efficiency of methylene blue (MB) dye as a function of the nanocomposites concentration from 1 to 5 g/L in solutions. While pristine TiO2 showed a maximum removal of ∼44%, the incorporation of the GO ensures the fast and complete elimination of MB within 9 min. The ball milling process contributed to the increase in the number of defects and surface area in the nanocomposites, which was demonstrated by ID/IG ratios by Raman spectroscopy and surface areas by BET. Pseudo-second-order and mechanistic kinetic models were considered, and the performed analysis points out the relevance of the pseudo-second-order model to account for the adsorption kinetics. The Langmuir and Freundlich isotherm models were applied to the experimental data to find an adequate model to describe the adsorption equilibrium, as well as the intra-particle diffusion model during the different adsorption stages involved in the TiO2/GO nanocomposites. The role of the oxidation degree of GO was clarified through their respective efficiency in the removal of the dyes.

Synthesis of NiO coated chitosan-cenosphere buoyant composite for enhanced adsorptive removal of methylene blue

The objective of the present study is to utilize fly ash cenosphere to remove methylene blue (MB) from the water streams. Nickel oxide is a typical semiconductor used as proficient adsorbent material for degradation of dye with environment friendly applications due to its excellent chemical stability and high catalytic activity. The chitosan cenosphere buoyant composite coated with NiO was synthesized with hydrothermal grafting reaction using silane coupling agent and epichlorohydrin as a cross-linking reagent. The batch adsorption experiments were carried out with a cationic dye, methylene blue as a representative organic pollutant to investigate the adsorptive capabilities of the composite as adsorbent. The influence of pH (2-12), initial concentration of dye (50–200 mg/L), temperature (37–47 °C) and contact time (0–24 h) were taken as parameters in the study. On the relative elimination of MB, the effect of time and temperature were investigated. The adsorption kinetics for MB was correlated and found to observe the pseudo-second order kinetic model, whereas the equilibrium adsorption isotherm follows the Langmuir model (R2 > 0.99). The results indicate that the floating fly ash cenosphere coated with NiO proved to be more responsive for enhanced degradation of methylene blue.

Adsorption behavior of rhamnolipid modified magnetic Co/Al layered double hydroxide for the removal of cationic and anionic dyes

In the present research, magnetic rhamnolipid-Co/Al layered double hydroxide (MR-LDH) was synthesized to uptake methylene blue (MB) and reactive orange 16 (RO16) from aqueous solution. The main parameters, including pH, adsorbent dosage, contact time, and initial analyte concentration, were optimized to achieve the best adsorption efficiency. Accordingly, the elimination of MB on MR-LDH is improved in the basic medium due to the electrostatic interactions between the negative charge of MR-LDH and the positive charge of MB dye. In contrast, the acidic medium (pH = 3) was favored for RO16 adsorption because of hydrogen bonding between the protonated form of azo dye and protonated hydroxyl groups at the surface of MR-LDH. The calculated maximum adsorption capacities for MB and RO16 were 54.01 and 53.04 mg/g at 313 K, respectively. The Langmuir model, which assumes monolayer adsorption on the adsorbent surface, provides the best explanation for the adsorption of both dyes (R2 = 0.9991 for MB and R2 = 0.9969 for RO16). Moreover, the pseudo-second-order kinetic model best described the adsorption process for MB (R2 = 0.9970) and RO16 (R2 = 0.9941). The proposed adsorbent maintains stable adsorption performance for four consecutive cycles. After each adsorption process, MR-LDH is easily separated by an external magnet. The findings show that MR-LDH was found to be an excellent adsorbent for the removal of both cationic and anionic organic dyes from aqueous solutions.

Adsorption of industrial dye onto a zirconium metal-organic framework: synthesis, characterization, kinetics, thermodynamics, and DFT calculations

Pollution that arises from textile industries is a serious environmental issue, and successful purifying has thus far proven to be difficult. In this study, environmentally safe Zr-metal-organic frameworks (Zr-MOF) were used to develop a strategy for removing Methylene Blue (MB) from water contaminants. The elimination of MB in wastewater samples by Zr-MOF showed good adsorption capability. SEM, FT-IR, XRD, XPS, and surface area confirmed that Zr-MOF has a large area of 1498 m2/g besides a microporous material having a pore diameter of 1.2 nanometers. The pH of the starting solution, amount of adsorbent used, contact period, and temperature were investigated. The pHPZC of Zr-MOF was 7.5. The adsorption of MB on Zr-MOF adsorbents was determined as sideways interrelations by a monolayer model based on the real gas law (MMRG) and a monolayer model based on the ideal gas law (MMIG). Zr-MOF has good capability for removing MB (1.58 mmol.g−1) and after numerous cycles, this performance remained; up to the sixth cycle, the adsorbent had recyclability of >91.6%. Adsorption experiments demonstrated that adsorption kinetics matched a pseudo-second-order model and the Langmuir equation. Activation energy was 15.87 kJ/mol. The microporous Zr-MOF adsorbent proved to be simple and effective for water purification.

Effective removal of organic dyes using the ultrasonic-assisted hydrothermal synthesis of NaP zeolite doping Cu or Fe in Fenton-like oxidation systems

NaP zeolite was successfully synthesized via ultrasonic-assisted hydrothermal synthesis. The approaches for Cu or Fe doping were screened. Additionally, the oxidation process of methylene blue (MB) and methyl violet-6B (MV-6B) by the doped NaPultra zeolites was surveyed. NaPultra zeolite exhibited higher crystallinity (94.99%), while the crystallization temperature and duration decreased from 120 °C to 90 °C and from 8 h to 4 h with the n(SiO2)/n(Al2O3) increasing from 2.0 to 4.0, compared to the hydrothermal synthesis. At the ultrasonic power intensity of 30% and the density of 60 mL/W, the conversion rates of Si and Al rosed from 66.46% to 84.68% and from 73.75% to 95.25%, respectively. Comparatively, the complexation approach demonstrated superior findings in the crystallinity (Fe-NaPultra: 92.37% and Cu-NaPultra: 94.14%) at the n(Fe(NO3)3):n(Al2O3) ratio of 1:4 and the n(Cu(NO3)2):n(Al2O3) ratio of 1:6. The ultrasonic resulted in the smaller crystal sizes for Fe-NaPultra (1.90 μm) and Cu-NaPultra (1.80 μm). Cu-NaPultra displayed better oxidation performance in the elimination of MB (93.22%) and MV-6B (98.71%) via the HO at the condition of pH = 5.0, 30 min, 2.5 g/L, 50 mg/L, and 25 °C. Through the combined action of adsorption and Fenton-like oxidation, the rapid enrichment of organic dyes by the zeolite was realized, and the dyes were removed efficiently. Cu-NaPultra was capable of retaining good removal performance throughout four cycles, suggesting that it is a promising catalyst for Fenton-like oxidation reactions and may help to pave the way for the removal of organic dyes.

Comparative study of ozonation and ozonation catalyzed by Fe-loaded biochar as catalyst to remove methylene blue from aqueous solution

Ozone-based processes gained much attention in recent years. However, due to low oxidative stability and utilization rate, single ozonation process (SOP) is insufficient for complete mineralization of pollutants. As a result, the single ozonation process is performed in the presence of a catalyst, a process known as catalytic ozonation process (COP). A promising catalyst (Fe/BC) was prepared by impregnating iron on biochar surface to remove methylene blue from aqueous solution via heterogeneous catalytic ozonation process (HCOP). The prepared Fe/BC features were characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and Brunauer–Emmett–Teller method (BET) before and after HCOP. Furthermore, the effect of various operating parameters such as ozone dose, catalyst dose, initial dye concentration, initial pH on the efficiency of SOP and HCOP were compared. In comparison to single ozonation process, the experimental study found that heterogeneous catalytic ozonation process has the highest efficiency. At pH 7.0, approximately 76% of methylene blue is removed during single ozonation process in 60 min. Heterogeneous catalytic ozonation process showed 95% methylene blue elimination from aqueous solution. The efficiency of heterogeneous catalytic ozonation process was decreased by 52% in the presence of hydroxyl radical (●OH) scavenger, indicating that hydroxyl is the major oxidant during heterogeneous catalytic ozonation process for the removal of methylene blue from aqueous solution. Fe/BC catalyst appears to have a lot of industrial promise, as well as the ability to remove methylene blue from aqueous solution via heterogeneous catalytic ozonation process.

Functionalized copper metal-organic framework with peroxidase-mimetic activity as an adsorbent for efficient removal of noxious organic dye from aqueous solution

We show that Cu-BDC-NH 2 could be employed as a peroxidase-mimetic catalyst for Fenton-like degradation of methylene blue (MB) in water. The three-dimensional copper-based MOF was constructed solvothermally by dissolving CuCl 2 .2H 2 O and 2-amine-1, 4-benzenedicarboxylic acid (1, 4-BDC-NH 2 ) in DMF. Transmission electron microscopy, Fourier transform infrared spectroscopy, Powder X-ray diffraction, the Brunauer–Emmett–Teller technique, Thermal Gravimetric Analysis, X-ray Photoelectron Spectroscopy, UV–Vis, and fluorescence spectroscopy were used to characterize the material. The influence of pH, temperature and concentration dose of Cu-BDC-NH 2 on MB degradation was examined. According to the results, not only does Cu-BDC-NH 2 sustain a reasonably high level of activity at pH 3, but it also work efficiently in a neutral to basic pH range, showing good stability and endurance. Under ideal conditions, full removal of MB was accomplished in 60 min. The peroxidase activity provided an advantage in removing the dye in a short period of time. Selective adsorption of dyes over Cu-BDC-NH 2 were also conducted by combining two cationic dyes. The elimination of MB was above 80% after four cycles, demonstrating the high recyclability. The results show that Cu-BDC-NH 2 not only significantly adsorbs the dye but also exhibits photocatalytic activity. Because of their good activity in broader pH range, higher temperature endurance and greater recyclability for MB removal, the treatment technique may be simplified for practical use and thereby lowering treatment costs. • Cu-MOF with peroxidase-like activity is used for removal of MB dye in water. • Complete removal of MB could be achieved in 60 min. • High selectivity towards MB was achieved in 10 min even under mixed dye conditions. • Cu-MOF showed good activity in different pH, higher temperature and are recyclable.

High-performance photocatalytic degradation of NiO nanoparticles embedded on α-Fe2O3 nanoporous layers under visible light irradiation

Thin layers of pure Fe2O3 and modified by polyvinyl alcohol (PVA) were synthesized by sol gel route. The morphology of Fe2O3 was modified by the creation of pores by evaporating the Polyvinyl alcohol at 550 °C. This modified structure improved the removal rate of methylene blue (MB) dye aqueous solution under visible irradiation in 10%. The effect of sensitization ratio of NiO nanoparticles onto Fe2O3/PVA (porous) showed very good degradation efficiency up to 100%. Characterization of Fe2O3, Fe2O3 modified by PVA (Fe2O3/PVA), Fe2O3/PVA/NiO have been used such as X-ray diffraction (XRD), FT-IR, scanning electron microscopy (SEM), UV–Vis … etc. The kinetic parameters of MB elimination by Fe2O3, Fe2O3/PVA and Fe2O3/PVA/NiO were calculated using linear models such as pseudo-first order (PFO), pseudo-second order (PSO) and Elovich. Four error functions were used namely, correlation coefficients (R2), Root Mean Square Error (RMSE), Mean Square Error (MSE) and Sum Squares Error (SSE), to better fit the kinetic equation. The MB elimination mechanism has been studied based on the intra-particle diffusion equation. The effect of pH on the MB removal rate by the two most active catalysts, Fe2O3/PVA and Fe2O3/PVA/with 1%wt. NiO nanoparticles, as well as the pHPZC point were evaluated.

A novel ZnWO4/MgWO4 n-n heterojunction with enhanced sonocatalytic performance for the removal of methylene blue: Characterizations and sonocatalytic mechanism

A novel ZnWO4/MgWO4 n-n heterojunction (0.9% ZnWO4/MgWO4) was fabricated successfully and characterized by different techniques. The methylene blue (MB) was removed to confirm the sonocatalytic activity by the 0.9% ZnWO4/MgWO4 composite. The sonocatalytic removal ratio of MB using MgWO4 was 40.04±4.34(%). It was significantly increased to 93.82±3.44(%) in the presence of 0.9% ZnWO4/MgWO4 composite. The significantly improved sonocatalytic performance was due to the form of n-n heterojunction, which could hinder the recombination of electron and hole (e−-h+) pairs effectively. The mechanism showed that hydroxyl radical (•OH) and h+ had important roles for the elimination of MB. Moreover, the 0.9% ZnWO4/MgWO4 composite had remarkable stability during the process of MB removal under the ultrasonic irradiation. The results suggested that the fabrication of heterojunction is a valid method to promote the sonocatalytic performance of catalyst. The results of this paper would provide valuable references for the development of new sonocatalysts used in environmental remediation.