Initial Methyl Orange Concentration Research Articles

Metal nanoparticles decorated mint-cellulose acetate composite as an efficient catalyst for the reduction of methyl orange

Water contamination caused by toxic compounds has emerged as one of the most severe challenges worldwide. Biomass-based nanocomposites offer a sustainable and renewable alternative to conventional materials. In this study, a nanocomposite of mint and cellulose acetate (Mint-CA) was prepared and employed as a supportive material for Cu nanoparticles (CuNPs) and Ag nanoparticles (AgNPs). The selectivity of CuNPs@mint-CA and AgNPs@mint-CA was assessed by comparing their performance in the reduction reaction of various dyes solutions. AgNPs@mint-CA exhibited superior catalytic performance, with a removal of 95.2 % for methyl orange (MO) compared to 68 % with CuNPs@mint-CA. The absorption spectra of MO exhibited a distinct peak at 464 nm. The reduction reaction of MO by AgNPs@mint-CA followed pseudo-first-order-kinetic with a rate constant of k = 0.0063 min−1 (R2 = 0.928). The highest removal of MO was achieved under the following conditions: a catalyst weight of 40 mg, an initial MO concentration of 0.07 mM, the addition of 0.5 mL of 0.1 M NaBH4, and a temperature of 25 °C. Furthermore, the AgNPs@mint-CA catalyst exhibited exceptional reducibility even after five use cycles, highlighting its potential for efficiently removing MO.

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).

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.

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.

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.

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.

Adsorption Process of Methyl Orange Dye onto Zinc Hydroxide Nitrate: Kinetic and Thermodynamic Studies

Zinc hydroxide nitrate (ZHN) was used as an anionic adsorbent for the removal of methyl orange (MO) dye from aqueous solutions. ZHN was characterized via X-ray diffraction (XRD) and infrared spectroscopy (FTIR) techniques. Investigations were carried out to see how the adsorption of MO was affected by factors such as initial MO concentration, contact time and temperature. Adsorption isotherms were analyzed using the Langmuir and Freundlich equations, with the first one being the better result for the equilibrium data. Adsorption kinetics was studied through applying pseudo-first and pseudo-second-order kinetic models, and the experimental data were better fitted to the pseudo-second-order model. The activation energy was determined using the Arrhenius equation to be 105.45 kJ mol−1, revealing the chemical nature of the adsorption process. The thermodynamic parameters were also determined, showing the adsorption of MO onto ZHN to be a non-spontaneous and exothermic process. The experimental results showed ZHN as a potential adsorbent with adsorption capacity for removing anionic dyes from water medium.

Characterization of a Ti/SnO2-Sb/Fe-PVP-PbO2 Electrode Deposited from Methanesulfonate Bath and Application in Electrocatalytic Degradation of MO

Ti/SnO2-Sb/PbO2 anodes were electrodeposited from methanesulfonate-based baths, and the effect of dopants such as PVP and Fe on the surface morphology, phase composition, electrocatalytic activity and stability was investigated. It is revealed that the inclusion of Fe effectively enhances the stability of PbO2 anode, while PVP can significantly improve its electrocatalytic activity. The Fe,PVP-codoped anode, Ti/SnO2-Sb/Fe-PVP-PbO2, exhibits the higher stability and electrocatalytic activity compared to the respective inclusion of Fe and PVP. The gradation efficiency of methyl orange (MO) on the Ti/SnO2-Sb/Fe-PVP-PbO2 anode is affected by the applied current density and the initial MO concentration. During degradation, the azo structure of MO is firstly cleaved, resulting in the rapid decolorization of solution. Demethylated MO and the anion of sulfanilic acid are detected as intermediates, and thus a plausible pathway of MO degradation is proposed.

Tuning the surface functionality of polyethylene glycol-modified graphene oxide/chitosan composite for efficient removal of dye

There has been a lot of attention on water pollution by dyes in recent years because of their serious toxicological implications on human health and the environment. Therefore, the current study presented a novel polyethylene glycol-functionalized graphene oxide/chitosan composite (PEG-GO/CS) to remove dyes from aqueous solutions. Several characterization techniques, such as SEM, TEM, FTIR, TGA/DTG, XRD, and XPS, were employed to correlate the structure–property relationship between the adsorption performance and PEG-GO/CS composites. Taguchi’s (L25) approach was used to optimize the batch adsorption process variables [pH, contact time, adsorbent dose, and initial concentration of methyl orange (MO)] for maximal adsorption capacity. pH = 2, contact time = 90 min, adsorbent dose = 10 mg/10 mL, and MO initial concentration = 200 mg/L were found to be optimal. The material has a maximum adsorption capacity of 271 mg/g for MO at room temperature. With the greatest R2 = 0.8930 values, the Langmuir isotherm model was shown to be the most appropriate. Compared to the pseudo-first-order model (R2 = 0.9685), the pseudo-second-order model (R2 = 0.9707) better fits the kinetic data. Electrostatic interactions were the dominant mechanism underlying MO sorption onto the PEG/GO-CS composite. The as-synthesized composite was reusable for up to three adsorption cycles. Thus, the PEG/GO-CS composite fabricated through a simple procedure may remove MO and other similar organic dyes in real contaminated water.

Rice husk charcoal and acid modified rice husk charcoal for efficient adsorption of methyl orange

Abstract In this study, methyl orange (MO) was removed from solution using rice husk charcoal (RHC) and acid modified rice husk charcoal (AMRHC). In batch adsorption mode, contact time (1–240 min), pH (3–10), adsorbent dose (1–30 g/L), and initial MO concentration (10–100 mg/L) were investigated. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to characterize the adsorbent's surface morphology and chemistry. At equilibrium, the highest removal of MO by RHC and AMRHC were 89 and 99%, respectively. Removal efficiency increased with increasing adsorbent dose, while the opposite was observed for adsorption capacity because of the availability of unsaturated adsorption sites. RHC and AMRHC were best described by the Freundlich and Langmuir isotherm models, with maximum adsorption capacities of 4.57 and 11.53 mg/g, respectively. The pseudo-second-order kinetic model fitted well for both adsorption and chemisorption, and the process was controlled by multi-step diffusion. Thermodynamic measurements proved that dye adsorption is a spontaneous endothermic process.

Cerium-phthalate coordination polymer as fenton-like durable catalyst for hydrogen peroxide activation and anionic organic dyes degradation in wastewater

This work presents the hydrothermal synthesis and characterization of cerium phthalate coordination polymer, Ce-Phth CP, from the inorganic precursor cerium sulphate and the organic linker phthalic acid. Characterization of Ce-Phth CP by SEM/EDX, XRD, and FTIR analyses show that Ce-Phth CP particles are made of rectangular bundled straws of micrometre dimension and can be categorized as crystalline material with some amorphousness. FTIR analysis demonstrates successful coordination of Ce(IV) with phthalate via the Ce–O bond. Ce-Phth CP was applied successfully for advanced oxidation processes (AOP) to degrade the stable azo dye methyl orange (MO) via the Ce-Phth CP/H2O2 heterogeneous catalysis system where the effect of initial pH (2, 7, 10), MO initial concentration (10, 20, 30 ppm) and Ce-Phth CP dosage (50, 100, 200 mg) were studied. Results show that H2O2 best decomposes at pH 10 (about 89% decomposition), while MO best degrades at pH 7 (about 98% degradation). pHPZC of Ce-Phth CP was determined as pH 7.4 which has shown a significant effect on the whole process, decomposition and degradation. Adsorption natures of both H2O2 and MO onto the Ce-Phth CP surface are suggested to be the reason behind the difference in this pH profile of H2O2 decomposition and MO degradation·H2O2 decomposition is shown to follow a regular second-order rate equation, while MO degradation follows the usual pseudo-first-order rate equation. For a selected conditions, Ce-Phth CP/H2O2 system showed 5-cycles reuse for MO degradation decreasing from 89.7% to 73.5%. In some detail, proposed mechanisms for H2O2 decomposition and MO degradation and the inter-relation between them are introduced to account for the best degradation at initial pH 7.

Microwave assisted zirconium oxide based catalytic activation of persulfate for methyl orange dye degradation

In this investigation, zirconium oxide (ZrO2) based activation of persulfate (PS) under microwave (MW) irradiation for methyl orange (MO) dye degradation was studied. ZrO2 was synthesized using facile hydrothermal method and it was characterized via XRD, FTIR, SEM, and TGA techniques. Subsequently, MW/ZrO2/PS experiments were conducted to explore the effect of ZrO2 dosage (0–1.5 g/L), initial MO concentration (15–250 mg/L), MW reactor temperature (60–90 ℃), MW power (240–700 W), PS dosage (50–250 mg/L), and presence of NaCl (0–5000 mg/L) on MO removal at pH ~ 7. Under the optimal conditions (ZrO2 ~ 0.5 g/L, MO concentration ~ 25 mg/L, MW temperature ~ 90 ℃, MW power ~ 560 W, and PS dose~250 mg/L), 99 % of MO removal and 85.9 % of TOC removal were observed. Moreover, the toxicity of the initial sample was reduced by 72.9 %. Interestingly, the catalytic oxidation of MO was not affected due to the presence of NaCl. Radical studies confirmed that SO4−⦁ radical was the major active species responsible for MO degradation. Subsequently, the central composite design (CCD) approach was used to find out the interaction effects between MO concentration (10–250 mg/L), PS dosage (50–500 mg/L), and MW treatment time (5–20 min) on MO removal. The CCD based response surface model was found to be significant and reliable (p < 0.0001). Moreover, the chemical cost and energy cost for MW/ZrO2/PS experiments under optimized condition was estimated as $22.5 and $30.3 per kg of MO removal. Overall, transition metal-based PS activation under MW irradiation could be one of the potential alternatives for dye wastewater treatment.

Biowaste-derived Ni/NiO decorated-2D biochar for adsorption of methyl orange

Eco-friendly carbothermal techniques were used to synthesize nanocomposites of biowaste-derived Ni/NiO decorated-2D biochar. The use of chitosan and NiCl2 in the carbothermal reduction technique was a novelty to synthesize the Ni/NiO decorated-2D biochar composite. Potassium persulfate (PS) was found to be activated by Ni/NiO decorated-2D biochar, which is thought to oxidize organic pollutants through an electron pathway designed by the reactive complexes formed between PS and the Ni/NiO biochar surface. This activation led to the efficient oxidation of methyl orange and organic pollutants. Analyzing Ni/NiO decorated-2D biochar composite before and after the methyl orange adsorption and degradation procedure allowed us to report on the process of its elimination. The Ni/NiO biochar with PS activation showed higher efficiency than Ni/NiO decorated-2D biochar composite as this material was able to degrade over 99% of the methyl orange dye. The effects of initial methyl orange concentration, dosages effect, solution pH, equilibrium studies, kinetics, thermodynamic studies, and reusability were examined and evaluated on Ni/NiO biochar.

Effect of Ag doping on photocatalytic activity of ZnO-Al2O3 derived from LDH structure: Synthesis, characterization and experimental study

In this research, Ag-ZnO-Al2O3 heterostructure catalyst was derived from the calcination of Ag-doped layered double hydroxide (LDH) through a solid-state process. With the aim of entirely understanding the structural and functional features, catalysts were analyzed by XRD, TGA/DTA, and FTIR techniques. The photocatalytic performance was evaluated by measuring the methyl orange (MO) photodegradation under UV irradiation. The impact of the key parameters, namely, irradiation time, catalyst dose, initial pH of solution, and the starting concentration of MO, were investigated and discussed. The characterization results exhibit a well crystallized hexagonal LDH structure. The experimental findings revealed approximately 95.8 % degradation yield after 210 min of irradiation for Ag-ZnO-Al2O3. The optimal conditions were found to be 20 mg/L of catalyst dose, 20 mg/L of MO initial concentration and initial pH of 4. In the whole, the results confirm that the Ag-ZnO-Al2O3 catalyst shows the highest adsorption and photocatalytic performances. After three recycling tests, the Ag-ZnO-Al2O3 photocatalyst maintained good recycling stability and a high photodegradation performance (90.7%). Finally, the use of Ag-ZnO-Al2O3 as heterostructure photocatalyst offer a promising approach for the degradation of more organic compounds in environmental remediation.

Adsorption of Methyl Orange Dyes on Oriented Co/Fe-MOF Bimetallic Organic Framework in Wastewater Treatment

The production of highly efficient and reusable adsorbents that can be used in pigment treatment has been of great scientific interest. Metallic organic frameworks (MOFs) are considered a new type of material with extremely diverse structures and can be used as adsorbents to remove environmental pollutants. The selected Co/Fe-MOF material was synthesized in this study by using the solvent-thermal method. Then, the effects of several influencing factors such as adsorbent dosage, pH, initial concentration of MO, and exposure time on the adsorption capacity of methyl orange (MO) dyes by Co/Fe-MOF were evaluated. Under acidic conditions (pH 4), the effective removal of MO from aqueous solution reached equilibrium after 60 min upon exposure to MO at the concentration of 200 mg/L, and the adsorption capacity was 137.6 mg/g. The two models of adsorption isotherms, Freundlich and Langmuir, showed good compatibility with the experimental data, and the calculated correlation coefficients (R2) were both greater than 0.96. The MO adsorption efficiency was proposed to fit the pseudo-quadratic and pseudo-first-order kinetic models. Therefore, MOF materials can be considered as a potential agent for wastewater treatment, thereby providing a possible solution to solve water pollution.

Recyclable Magnetic Iron Immobilized onto Chitosan with Bridging Cu Ion for the Enhanced Adsorption of Methyl Orange.

Chitosan (CS) is a natural and low-cost adsorbent for capturing metal ions and organic compounds. However, the high solubility of CS in acidic solution would make it difficult to recycle the adsorbent from the liquid phase. In this study, the CS/Fe3O4 was prepared via Fe3O4 nanoparticles immobilized onto a CS surface, and the DCS/Fe3O4-Cu was further fabricated after surface modification and the adsorption of Cu ions. The meticulously tailored material displayed the sub-micron size of an agglomerated structure with numerous magnetic Fe3O4 nanoparticles. During the adsorption of methyl orange (MO), the DCS/Fe3O4-Cu delivered a superior removal efficiency of 96.4% at 40 min, which is more than twice the removal efficiency of 38.7% for pristine CS/Fe3O4. At an initial MO concentration of 100 mg L-1, the DCS/Fe3O4-Cu exhibited the maximum adsorption capacity of 144.60 mg g-1. The experimental data were well explained by the pseudo-second-order model and Langmuir isotherm, suggesting the dominant monolayer adsorption. The composite adsorbent still maintained a large removal rate of 93.5% after five regeneration cycles. This work develops an effective strategy to simultaneously achieve high adsorption performance and convenient recyclability for wastewater treatment.