Methyl Orange Concentration Research Articles

NH2-UiO-66 (Zr) modified waste wool fibers for efficient adsorption of dye from water

Developing low-cost and stable adsorbent is urgent and attractive to remove hazardous dye from water. In this study, zirconium based metal-organic framework (NH2-UiO-66) was grown on waste wool fibers and the fabricated composite adsorbent (NH2-UiO-66/wool) was used to remove anionic dye methyl orange (MO). After characterizing the adsorbents, we determined the effect of pH and initial concentration of MO on adsorption performance. Moreover, adsorption kinetics and isotherms were conducted to reveal the adsorption mechanism. The results showed that NH2-UiO-66/wool achieved the highest adsorption capacity at natural pH with the maximum adsorption of 61.0 mg/g adsorbent, which is higher than most biomass based adsorbents. Moreover, NH2-UiO-66/wool enabled a broad range of pH (3−11) and initial concentration of MO (10–50 mg/L). Adsorption kinetics and isotherms of NH2-UiO-66/wool fitted well with pseudo-second-order model and Langmuir mode, respectively. NH2-UiO-66/wool presented 40.3 times higher of kinetics constant than that of original wool in the presence of initial MO concentration of 10 mg/L due to the positive nature of NH2-UiO-66. Ultimately, NH2-UiO-66/wool presented excellent regeneration ability with 500 mg/L NaCl solution and regeneration efficiency remained 98% after 10 cycles. Overall, this work may provide new insights into the development of MOFs/wool adsorbents for enhanced dye removal.

Bio-based aerogel composites of coconut pith-derived carbon and chitosan for efficient anionic dye-polluted water treatment

Abstract Biomass-based aerogels are of interest due to their abundant precursors, ease of functionalization, eco-friendliness, low cost, and effectiveness in dye-contaminated water treatment. Coconut pith (CP) known as a by-product after coconut processing is a sponge-like and lightweight material discarded in large volumes. For the first time, carbon micro-particles resulting from two-step treatment and pyrolysis of CP have been successfully incorporated with chitosan to produce aerogel composites by high-speed homogenization and freeze-drying. After pretreatment, holocellulose content and crystallinity index of the recovered CP pulp are respectively 75.4 and 58.6 % along with a solid recovery rate of 27.5 %. Characteristic properties of the aerogel composites are featured by their density as low as 15.23–28.17 mg/cm3, remarkably high porosity of 98.17–99.05 %, and Young’s modulus of 1.64–12.23 kPa. Synergistic effects of the porous network, electrostatic interactions between both amine groups in chitosan and carbon surface with methyl orange (MO) cause the as-fabricated aerogel composites to achieve an extremely high adsorption capacity of 454.13 mg/g and removal efficiency of 92.32 % at initial MO concentration of 500 mg/L. Therefore, the CP-derived carbon/chitosan aerogel composites synthesized from a feasible procedure exhibit their great potential in enhancing the value of coconut waste and dealing with dye-contaminated water pollution by simple and economical adsorption.

Photocatalytic degradation of methyl orange using CuO/Al2O3 nanocomposite obtained by microwave-assisted thermal decomposition route

Aluminum oxide (Al2O3) and copper oxide (CuO) are known to exhibit very exceptional properties including high thermal and chemical properties that promise a wide area of applications. In this paper, we report the microwave-assisted thermal decomposition route to CuO/Al2O3 nanocomposite and its application as a photocatalyst for methyl orange (MO) degradation. Al2O3 was first prepared at different temperatures of 900, 1000, and 1100 °C, denoted as Al2O3(1), Al2O3(2), and Al2O3(3). Subsequently, the best temperature (1000 °C) was selected for the synthesis of CuO/Al2O3 nanocomposite. XRD analysis confirmed the hexagonal crystal structure for all the Al2O3 and the monoclinic phase for the CuO within the composite. The crystallite sizes of the alumina increased with temperature and a similar growth pattern occurred in the entire samples. Scanning electron microscopy and transmission electron microscopy (SEM and TEM) show clear spherical morphology for all the samples with obvious agglomeration as temperature increases. Optical characterization displayed decreasing band gap energies with increasing temperature, implying size increase due to particle interaction, boundary energy reduction, and grain boundary migration. The photocatalytic performance of the CuO/Al2O3 under visible light was evaluated on methyl orange (MO), and the degradation was studied with some process parameters such as the effect of catalysts dosage and initial concentration of MO. Results showed that the CuO/Al2O3 exhibited about 94.2 % efficiency within 3 h using an optimum dose of 2.0 g/L and an initial MO concentration of 20 mg/L. However, the use of CuO/Al2O3 nanocomposites to remove other organic pollutants could confirm the robustness of this catalyst.

Efficient degradation of methyl orange in wastewater via bio‐electro‐Fenton system: optimization, pathway investigation and process evaluation

AbstractBACKGROUNDThe efficient and green technology of dye removal has been widely investigated. In this study, a bio‐electro‐Fenton system was used to degrade methyl orange (MO). For the system optimization, five experimental groups were detected, including pH (1–6), iron (Fe2+) concentration (3–15 mmol L−1), airflow rate (0–20 mL min−1), external voltages (0.2–1.0 V) and initial MO concentration (20–100 mg L−1).RESULTSOptimal conditions of pH 3, Fe2+ concentration 9 mmol L−1, air flowrate 12 mL min−1, external voltage of 0.6 V and MO concentration 60 mg L−1 were selected, resulting in a 92% efficiency. For the pathway investigation of MO degradation, under oxidization by ˙OH, demethylation, broken azo bonds and broken benzene ring structure were obtained. Intermediate products were predicted. For the system evaluation, energy consumption of 0.15–0.59 KWh was determined for 1 m3 MO wastewater. The total cost of degrading MO wastewater could decrease to US$470.0 m−3 by adjusting operational time.CONCLUSIONConsidering the Fe2+ regeneration and the low energy consumption, this bio‐electro‐Fenton system can be considered as one of the most environmentally‐friendly approaches for MO degradation; however, quantitative evaluation on sustainability needs to be further discussed via advanced assessment tools (such as life‐cycle assessment). © 2024 Society of Chemical Industry (SCI).

Removal of Methyl Orange from Aqueous Solution Using Orange Peel as a Low Cost Adsorbent

The objective of this research was to evaluate the feasibility of using orange peels as a low-cost adsorbent to remove methyl orange (MO) from water solutions. The orange peel adsorbent underwent characterization through Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR) Spectroscopy to determine its properties before and after adsorption. A series of batch adsorption experiments were carried out to investigate the effects of various parameters such as contact time, adsorbent dosage, particle size, and initial dye concentration on the adsorption process. In each case, varying the value of the parameter of interest while keeping all other parameters constant. Results revealed that the highest removal of the dye from the adsorbent was achieved at a contact time of 90 min, the adsorbent dosage of 0.5 g, a particle size of less than 63 µm, and an initial concentration of 300 mg/L. Furthermore, the adsorption rate increased with increasing contact time, adsorbent dosage, and initial concentration, while it decreased with increasing particle size of the adsorbent. Concentrations of methyl orange were analyzed using a UV-Vis spectrophotometer. The experimental equilibrium data was analyzed using Langmuir and Freundlich isotherm models. The Langmuir isotherm provided the best fit for the experimental data with a correlation coefficient value of 0.9964 and a maximum adsorption capacity of 17.69 mg/g.

Graphene Nanocomposites in the Treatment of Pancreatic Cancer

The application value of titanium dioxide (TiO2)/graphene nanocomposites in photothermal therapy of pancreatic cancer (PC) was explored. Using scale graphite as raw material, graphene was obtained by Hummer oxidation method and hydrazine hydrate reduction method, and then TiO2/graphene nanocomposites were prepared by ultrasonic heating. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and degraded methyl orange solution were adopted to detect the surface structure, particle size, element morphology, and photocatalytic activity under different composite ratios, different sonication times, and different heating temperatures. Human normal pancreatic ductal epithelial cell line HPDE6-C7 and human metastatic PC cell AsPC-1 were adopted as research models. The cytotoxicity of TiO2/graphene nanocomposites and the killing effect of photothermal therapy based on TiO2/graphene nanocomposites were analyzed by water soluble tetrazolium salt colorimetric assay (WST-1) and methyl thiazolyl tetrazolium salt colorimetric assay (MTT). The results suggested that when the ratio of graphene to TiO2 was 50:1, the ultrasonic time was 100 min, and the heating temperature was 200 °C, TiO2 was better attached to the surface of graphene, the distribution of particles was relatively more uniform, and the concentration of methyl orange was relatively lowest. The XRD pattern showed that the diffraction peak of the doped TiO2/graphene nanocomposite was basically the same as that of the pure TiO2. When the ultrasonic time was 100 min, the diffraction peak intensity in the XRD pattern was the largest. As for AsPC-1 cells, the cell viability was obviously lower than 0.1/1/10/100 μm/mL when the concentration of TiO2/graphene nanocomposites was 500 μm/mL (P <0.05). For HPDE6-C7 cells, when the concentration of TiO2/graphene nanocomposites was 100 and 500 μm/mL, the cell viability was obviously lower than 0.1/1/10 μm/mL (P <0.05), and 500 μm/mL was the lowest. The cell killing rate in group D was clearly higher as against groups A, B, and C (P <0.05). Graphene: The optimal preparation conditions of TiO2/graphene nanocomposites are 50:1, 100 min of ultrasound time, and 200 μC of composite temperature. The photothermal therapy based on TiO2/graphene nanocomposites can effectively kill PC cells, and has a good potential in the field of hyperthermia for pancreatic tumors.

Adsorptive removal of organic pollutants from aqueous solutions using novel GO/bentonite/MgFeAl-LTH nanocomposite

The contamination of water with organic pollutants such as dyes and phenols is a serious environmental problem, requiring effective treatment methods. In the present study, a novel nanocomposite was synthesized by intercalating graphene oxide and bentonite clay into MgFeAl-layered triple hydroxide (GO/BENT/LTH), which was characterized using different techniques. The adsorption efficacy of the GO/BENT/LTH nanocomposite was assessed via the removal of two harmful organic water pollutants, namely methyl orange (MO) and 2-nitrophenol (2NP). The obtained results revealed that the maximum adsorption capacities (qmax) of MO and 2NP reached 3106.3 and 2063.5 mg/g, respectively, demonstrating the excellent adsorption performance of the nanocomposite. Furthermore, this study examined the effects of contact time, initial MO and 2NP concentrations, pH, and temperature of the wastewater samples on the adsorptive removal of MO and 2NP by the GO/BENT/LTH nanocomposite. The pH, zeta potential, and FTIR investigations suggested the presence of more than one adsorption mechanism. Thermodynamic investigations elucidated the exothermic nature of the adsorption of MO and 2NP onto the GO/BENT/LTH nanocomposite, with MO adsorption being more sensitive to temperature change. Additionally, regeneration studies revealed a marginal loss in the MO and 2NP removal with the repetitive use of the GO/BENT/LTH nanocomposite, demonstrating its reusability. Overall, the findings of this study reveal the promise of the GO/BENT/LTH nanocomposite for effective water decontamination.

PH dependent synthesis of ceria nanoparticles for efficient sunlight-driven photocatalysis of methyl orange containing wastewater

In this study, cerium nitrate hexahydrate was used as a precursor to create nanocrystalline ceria nanoparticles, which were then created utilizing a simple and economical sol-gel method by adjusting the pH of the reactants between 6 and 12. Under direct sun radiation, wastewater containing methyl orange (MO) was photodegraded using the produced CeO2 NPs. For recent photocatalysis experiments, the degree of crystallinity, shape, dimensions, and degree of MO photodegradation were characterized and analyzed using XRD, FTIR, SEM, and UV–Vis spectrometry. According to the results, the pH of the synthesis solutions had a significant impact on the ceria-based photocatalysis of MO. Ceria NPs synthesized at a pH of 8 demonstrated optimal photocatalytic activity. Moreover, the results showed that variation in catalyst loading, initial concentration of MO, pH of MO-wastewater as well as exposure time have significantly impacted on photocatalytic performance of optimized CeO2. The optimum percentage degradation of around 75 % of MO was achieved in 80 min exposure of sunlight. Optimized low-cost ceria NPs prepared herein may be employed for dyes containing industrial wastewater treatment throughout the year using ordinary sunlight.

Study on adsorption of methyl orange by waste tea

The adsorption effect of waste tea leaf on dye methyl orange was studied. The tea after decolorization for 6 h was modified with potassium permanganate, and then the adsorption properties of unmodified and potassium permanganate modified tea to methyl orange were studied. The influence of the optimal pH value, dosage of unmodified and modified tea, initial concentration of methyl orange, adsorption temperature and contact time variables of methyl orange and tea powder on the adsorption performance was obtained in the experiments. Under the optimized conditions, the maximum adsorption rate of potassium permanganate-modified tea leaves was 99.82 %, and the maximum adsorption capacity was 3.9928 mg/g. The kinetics, thermodynamics and adsorption properties of methyl orange by KMnO4 activated tea and unmodified teas were studied. The adsorption kinetics results showed that the adsorption was in accordance with the pseudo-second-order kinetic equation. The adsorption thermodynamics results showed that the adsorption process was exothermic and the entropy decreased. The research results of adsorption isotherms showed that the adsorption process was in accordance with the Freundlich adsorption isotherm. Scanning electron microscopy, X-ray diffraction and infrared spectroscopy were used to characterize KMnO4 activated tea powder samples. This method can adsorb methyl orange, reduce the concentration of methyl orange in wastewater and the damage to the environment.

Insights into the photocatalytic role of glycine-assisted sol-gel auto-combustion synthesized (Co, Mn)(Co, Mn)2O4 nanostructures for efficient visible light-driven degradation of methyl orange

Research on the use of new materials and the improvement of existing fast ways for removal of water pollutants is still challenging. This work documented rational fabrication of (Co, Mn)(Co, Mn)2O4 nanoparticles as nano-photocatalyst materials with improved charge carrier separation and strong redox potential for efficient degradation of methyl orange (MO) in wastewater. This investigation illustrated that the Co/Mn molar ratio can greatly affect the textural and structural properties. From the point of view of size and shape, the optimum product with 1:3 M ratio of Co to Mn precursors was selected as a catalyst in the photocatalysis process. The prepared highly crystallized phase of tetragonal (Co, Mn)(Co, Mn)2O4 describe an optical band gap of 1.7 eV, according to the DRS data, which make them as efficient visible driven photocatalysts. The photodegradation experiments of spinel mixed structures were assessed by investigation of photocatalyst dosages and initial MO concentrations to unravel how these operational parameters affect Co-Mn-O photocatalysis. A remarkable discoloration capability of 68.07 % could result from the catalyst dosage of 0.04 g and dye concentration of 15 mg/L after 120 min of visible light. The kinetics survey further unveiled the maximum rate constant of 0.0080 min−1 for the MO degradation. In the scavenger trials, singlet oxygen (1O2) and superoxide (●O2−) radicals were principal reactive oxygen species (ROS) responsible for pollutant photodegradation in the presence of pure (Co, Mn)(Co, Mn)2O4 structures. In addition, the cyclic performance of catalyst depicted a removal efficiency of 60.1 % over 5 runs.

Selective separation of methylene blue from aqueous solution using Mn/Pd decorated chemically modified MoS2 nanocomposites

The presence of dyes in wastewater is posing as serious threat to human health. There are a huge number of physical, chemical, biological and hybrid methods available for the removal of colorants (dyes) from aqueous environment. In this work, we demonstrate the fabrication of new nanocomposites, MoS2-COOH/gly@M (M= Mn, Pd), with high adsorption property fabricated by chemically immobilizing manganese and palladium metallic centers onto the glycine- modified molybdenum disulfide (MoS2) material. The chemical and physical properties of adsorbents were analyzed using Fourier transform infrared spectrometer (FT-IR), thermal gravimetric analysis (TGA), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) companied by energy dispersive X-ray and mapping (EDAX & MAP) analyses. Zeta potential (ξ) technique was also used to measure the surface charge of adsorbents. Performances of nanocomposites were investigated on the sewage as adsorbent for dye removal. Synthesized nanocomposites revealed selective adsorption of methylene blue (MB) dye from aqueous mixture of MB and methyl orange (MO). Results displayed the equivalent high adsorption capacity for MB and MO up to 553 and 619 mg/g, respectively (green reaction condition= 120 min contact time, ,25 °C, pH 2.0 and pH 7.0, in the presence of 2 mg adsorbent and 50 mg/L (30 mL) initial concentration of MO and MB). The remarkable adsorption capacity of dye by MoS2-COOH/gly@M (M= Mn, Pd) nanocomposites can be attributed to the intermolecular interactions due to the presence of the amine, hydroxyl, and carboxyl functionalities. To describe the adsorption mechanism of MO and MB dye by synthesized nanomaterials, the pseudo-first-order and pseudo-second-order kinetics were further studied. Isotherm models displayed that the adsorption of MB and MO onto the MoS2-COOH/gly@M (M= Mn, Pd) nanocomposites is more correspondent with the Freundlich model with high-correlation coefficients. The results showed that the electrostatic attraction and H-bonding interaction were the basic cause of the adsorption of these anionic and cationic dyes on the surface of the nanocomposites. One of the distinguished properties of adsorbents is their capability to selectively adsorb MB from an admixture of MO and MB. The adsorption selectively has expanded in the following order: MoS2 < MoS2-COOH/gly@Mn < MoS2-COOH/gly@Pd. Based on the results, this new type of nanocomposites has potential to act as an effective and affordable adsorbent material for dye removal from an industrial sewage.

Effective investigation of electro-catalytic, photocatalytic, and antimicrobial properties of porous CuO nanoparticles green synthesized using leaves of Cupressocyparis leylandii

In this study, green copper oxide nanoparticles (G-CuO NPs) were successfully synthesized using a green co-precipitation method employing natural reducing agents from Cupressocyparis leylandii leaf extracts. Characterization of the biosynthesized G-CuO NPs using SEM-EDS, XRD, UV, and FTIR techniques revealed a spherical structure with a crystallite size of 17.09 nm and a bandgap energy of 3.24 eV, confirming the successful synthesis of high-quality CuO nanoparticles. The electrochemical properties of the prepared G-CuO NPs modified carbon paste electrode (G-CuO-MCPE) were investigated for the detection of Methyl Orange (MO) using the cyclic voltammetric method. A 2 mg G-CuO-MCPE exhibited a significant current sensitivity of 60.5 µA at pH 7.2, which is at least seven times higher than that of the bare carbon paste electrode (BCPE). The effect of different G-CuO-MCPE concentrations, pH values, scan rates, and MO concentrations on electrochemical detection was also investigated. Additionally, the antibacterial activity of G-CuO NPs against Escherichia coli and Bacillus subtilis bacteria, and the photocatalytic activity of G-CuO NPs synthesized biosynthetically on the degradation of Methylene Blue (MB) dye under simulated sunlight irradiation were evaluated. The G-CuO NPs demonstrated high antibacterial activity against both Gram-negative (E. coli) and Gram-positive (B. subtilis) bacteria. Acting as a catalyst, G-CuO degraded 92.3 % of MB dye under solar irradiation

Photocatalysis of silicon nanowires decorated with metallic nanoparticles and graphene oxide under different light intensities

This work shows silicon nanowires (SiNWs), decorated with different nanoparticles, as a photocatalytic material under different lighting conditions. In this system, the comparison between different materials and the influence of light intensity on their performances are studied. On the other hand, the synthesis of SiNWs was done by a metal-assisted chemical etching. The decoration with nanoparticles of copper CuNPs and cuprous oxide CuO2NPs was conducted with the electroless technique. Graphene oxide (GO) lamellar particles passing through an atmospheric pressure plasma (APPJ) were instantaneously ionized losing OH radicals and connecting them into a continuous coating around the SiNWs nanostructures. Such a layer with a large contact area among SiNWs/GO/Cu/CuO2 was obtained with a small thickness of about 10–20 nm. This is proposed to allow and increase charge carrier transference to the aqueous solution for redox reactions to degrade the dye molecules. Through statistical analysis, we compared the percentages of the decrease in methyl orange concentration used to measure the photocatalytic performance. SiNWs – CuNPs surfaces, in combination with high-intensity light, exhibit higher degradation percentages and rate constants. The graphene oxide coatings were deposited on monocrystalline silicon wafers and silicon nanowires, constituting a semiconductor-semiconductor heterojunction. This is an innovation proposed in this work that could lead to the fabrication of semiconductor heterojunctions with Z-scheme complementarity.

Eggshell-Derived Copper Calcium Hydroxy Double Salts and Their Activity for Treatment of Highly Polluted Wastewater.

By using methyl orange (MO) removal as a model reaction, the best temperatures for processing eggshells are 750 °C and above to obtain biobased CaO materials, a raw material for producing CuCa hydroxy double salt (HDS) materials with high efficiency in treatments of highly polluted wastewater (the initial concentration of MO is 500 ppm). Characterization techniques employed in this study include power X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, nitrogen adsorption-desorption analysis, and the colorimetric method, as well as energy-dispersive X-ray, infrared-, and electron spin resonance spectroscopies. Complete MO removal and high chemical oxygen demand (COD) efficiencies (>90%) can be achieved after 3 min treatments of the aqueous MO with the calcined eggshell-derived CuCa HDS materials. The spent, deactivated HDS materials can be regenerated by an acid wash method. The activity of CuCa HDS materials in MO removal is unaffected by eggshell sources, implying that sorting steps may be unnecessary when eggshell food waste (duck, quail, and hen eggshells) is collected to produce biobased CaO. The findings of this study demonstrated that eggshells can be used in place of limestone and could be a more sustainable, renewable, and cost-effective source for material development and other applications.

Preparation of Rumex abyssinicus based biosorbent for the removal of methyl orange from aqueous solution

Methyl orange is abundantly present in wastewater generated from textile industries causing serious human health and environmental problems. Therefore, this study was aimed at preparing a low cost and effective biosorbent from the stem of Rumex abyssinicus plant for the removal of methyl orange from aqueous solution. Characterization of the prepared adsorbent material was carried out using a pH point of zero charge, Scanning Electron microscope (SEM), Fourier Transform Infrared (FTIR) spectroscopy and X-Ray Diffraction (XRD). The design and optimization of methyl orange batch adsorption was carried out using the Box Behnken approach to Response Surface methodology aiming to reduce the experimental runs and time with adequate results. The characterization of the adsorbent revealed 7.9 (pHpzc), porous and heterogonous surface (SEM), presence of multiple functional groups (FTIR) and amorphous structure (XRD). The maximum removal efficiency of 98.5 % was found at pH, contact time, Methyl orange concentration and adsorbent dosage of 6, 60 min, 20 mg/L and 0.2 g/100 mL respectively. The isotherm studies were carried out using Langmuir, Freundlich, Toth and Koble Corrigan models in which Freundlich isotherm with a maximum R2 of 0.95 was found to fit data best showing heterogeneous and multilayer surface interaction. On the other hand, a kinetics study revealed that pseudo-second-order fitted the data best. Moreover, the thermodynamics analysis showed the nature of the adsorption to be endothermic, spontaneous and feasible. Generally, this work proved that the low-cost, environmentally friendly and easily prepared Rumex abyssinicus-based material could be an alternative adsorbent for dye detoxification at an industrial scale.

Sorption of methyl orange molecules on polyacrylonitrile-coated kapok fibers in a fixed bed set-up at dynamic conditions

Polyacrylonitrile-coated kapok fibers (PAN-KF) were used as sorbent material for methyl orange (MO) dye under dynamic conditions using a fixed bed set-up. The PAN molecules were coated on kapok fibers using a facile surfactant-assisted technique. In this technique, cetyltrimethylammonium bromide (CTAB) molecules were used as the surfactant and acrylonitrile as the precursor monomer. PAN-KF successfully absorbed MO under dynamic conditions. Long breakthrough and exhaustion times were achieved at lower initial concentration of methyl orange, higher bed height, and slower flow rate. Furthermore, PAN-KF sorbent in a fixed bed set-up has larger removal efficiency and exhaustion capacity compared to that of activated charcoal with the same mass and bed height.

SnAg2O3-Coated Adhesive Tape as a Recyclable Catalyst for Efficient Reduction of Methyl Orange.

Silver oxide-doped tin oxide (SnAg2O3) nanoparticles were synthesized and different spectroscopic techniques were used to structurally identify SnAg2O3 nanoparticles. The reduction of 4-nitrophenol (4-NP), congo red (CR), methylene blue (MB), and methyl orange (MO) was studied using SnAg2O3 as a catalyst. Only 1.0 min was required to reduce 95% MO; thus, SnAg2O3 was found to be effective with a rate constant of 3.0412 min-1. Being a powder, SnAg2O3 is difficult to recover and recycle multiple times. For this reason, SnAg2O3 was coated on adhesive tape (AT) to make it recyclable for large-scale usage. SnAg2O3@AT catalyst was assessed toward MO reduction under various conditions. The amount of SnAg2O3@AT, NaBH4, and MO was optimized for best possible reduction conditions. The catalyst had a positive effect since it speed up the reduction of MO by adding more SnAg2O3@AT and NaBH4 as well as lowering the MO concentration. SnAg2O3@AT totally reduced MO (98%) in 3.0 min with a rate constant of 1.3669 min-1. These findings confirmed that SnAg2O3@AT is an effective and useful catalyst for MO reduction that can even be utilized on a large scale for industrial purposes.

Preparation and characterization of a novel nanocomposite based on MnCr-layered double oxide and CoFe2O4 spinel ferrite for methyl orange adsorption

Herein, the adsorption of methyl orange (MO), a dangerous anionic dye, from an aqueous solution was investigated using a novel magnetic nanocomposite adsorbent. A nanocomposite entitled manganese chromium-layered double oxide/cobalt spinel ferrite, (MnCr)-LDO5wt.%/CoFe2O4, which links the interlayer structural characteristics of layered double oxides (LDOs) with the magnetic properties of spinel ferrites (SFs) was synthesized using the eco-friendly co-precipitation technique. Determination of structural parameters, crystallite size, and micro-strain was done using X-ray diffraction (XRD) analysis. Transmission electron microscopy (TEM) was used to determine grain shape and size. Surface analysis was performed using X-ray photoelectron spectroscopy (XPS) to identify elements and oxidation states present in the prepared nanocomposite. Vibrating sample magnetometer (VSM) was utilized to examine the magnetic characteristic. A comprehensive comparative study about the effectiveness and durability of CoFe2O4 and (MnCr)5wt.%/CoFe2O4 as nanoadsorbents for MO was conducted. Numerous variables, including contact time, MO concentration, adsorbent dosage, and pH were tested for their effects on the adsorption removal percentages. The findings showed that the maximum removal percentage was 86.1% for 25 ppm of MO was for 0.1 g/100 mL of (MnCr)-LDO5wt.%/CoFe2O4 at pH = 3. Investigations of isotherms and kinetics were conducted under batch conditions. The Langmuir isotherm matched the experimental data, for both nanoadsorbents, quite well due to the homogeneous distribution of active sites. Adsorption kinetics data were found to be compatible with intra-particle diffusion and pseudo-second order models for CoFe2O4 and (MnCr)5wt.%/CoFe2O4, respectively. A total of five adsorption–desorption cycles were performed to determine the prepared adsorbents’ recyclable nature.

Simultaneous microbial electrochemical degradation of methyl orange and bioelectricity generation using coculture as anode inoculum in a microbial fuel cell

Methyl Orange, an azo dye, is a widely used colouring agent in the textile industry. The study aimed to investigate the efficiency of bioremediating bacteria in degrading methyl orange. Escherichia coli (E. coli), a Methyl Orange-degrading bacterium, was isolated from cow dung and its biochemical properties were analysed using 16S rRNA sequencing, and MALDI-TOF MS. A pre-cultured strain of Pseudomonas aeruginosa was co-cultured with E. coli in 1:1 ration in a microbial fuel cell (MFC) for simultaneous electricity production and methyl orange degradation. The degradation was combined with biological wastewater treatment at varying Methyl Orange concentrations, and the electrochemical characteristics were analysed through polarisation study, cyclic voltammetry, and electrochemical impedance spectroscopy. The impact of parameters such as anolyte pH, dye concentration, incubation time, and substrate concentrations were also studied. This study confirmed E. coli as an effective methyl orange degrading bacteria with a maximum % degradation efficiency of 98% after 48 h incubation at pH 7.0. The co-culture of isolated microorganisms at 250 mg/L of methyl orange concentration showed a maximum power density 6.5 W/m3. Further, anode modification with Fe2O3 nanoparticles on the anode surface enhanced power production to 11.2 W/m3, an increase of 4.7 W/m3.

High performance photocatalyst TiO2@UiO-66 applied to degradation of methyl orange

MOFs have considerable adsorption capacity due to their huge specific surface area. They have the characteristics of photocatalysts for their organic ligands can absorb photons and produce electrons. In this paper, the photodegradation properties of TiO2 composites loaded with UiO-66 were investigated for the first time for MO. A series of TiO2@UiO-66 composites with different contents of TiO2 were prepared by a solvothermal method. The photocatalytic degradation of methyl orange (MO) was performed using a high-pressure mercury lamp as the UV light source. The effects of TiO2 loading, catalyst dosage, pH value, and MO concentration were investigated. The results showed that the degradation of MO by TiO2@UiO-66 could reach 97.59% with the addition of only a small amount of TiO2 (5 wt%). TiO2@UiO-66 exhibited significantly enhanced photoelectron transfer capability and inhibited efficient electron–hole recombination compared to pure TiO2 in MO degradation. The composite catalyst indicated good stability and reusability when they were recycled three times, and the photocatalytic reaction efficiencies were 92.54%, 88.76%, and 86.90%. The results provide a new option to design stable, high-efficiency MOF-based photocatalysts.