Azo Dye Methyl Orange Research Articles

Plasma and radiation mediated green synthesis of gold Nanoparticles-immobilized bio-template based catalytic reactor ‘AuNICaR’: Mechanistic insights, catalytic performance and reusability analysis

The present work reports a green, non-thermal plasma-based approach for efficient synthesis of a gold nanoparticles (Au NPs) Immobilized Catalytic Reactor “AuNICaR” via a novel, efficient, indigenously developed process termed “Plasma Assisted Synthesis and Simultaneous Immobilization (PASSI)”, using isopropanol to enhance the reducing plasma environment. Au NPs were synthesized and simultaneously immobilized onto a cellulose based bio-template pre-functionalized via radiation induced grafting of 2,3-epoxypropylmethacrylate (EPMA) onto a nonwoven cellulose (NWC) substrate. The process entails minimal wastage of expensive gold precursor and eliminates use of external chemicals (reducing and stabilizing agents). Samples were characterized by 13C NMR, FTIR, XPS, TGA, DSC, SEM-EDS, BET, and EDXRF analysis. Catalytic activity was assessed by spectrophotometrically monitoring the reduction of p-nitroaniline (PNA) in presence of NaBH4. DFT calculations established the interaction between Au NPs and EPMA groups of the bio-template to be occurring in ratios of 1:1 and 1:2, with 1:1 being more stable. ANN modelling was also invoked to investigate the effect of simultaneous variation of plasma process parameters on the catalytic performance. AuNICaR was demonstrated for catalytic reduction of pollutants: PNA, p-nitrophenol (PNP) and methyl orange (MO) azo dye in both batch and continuous flow mode. Over 25000 mL of cumulative pollutant feed with concentrations ranging from 0.06 mM − 2 mM was treated at a flow rate of 540 mL.h−1, using a single catalyst batch after intermittent washing with water. With excellent storage stability of > 12 months and > 92 % retention in catalytic activity post multiple cycles, AuNICaR certifies as a potentially inexhaustible catalytic system for cost-effective pollutant treatment.

Fungus mediated synthesis of biogenic palladium catalyst for degradation of azo dye.

Dyes are the coloured substances that are applied on different substrates such as textiles, leather and paper products, etc. Azo dyes release from the industries are toxic and recalcitrant wastewater pollutants, therefore it is necessary to degrade these pollutants from water. In this study, the palladium (0) nanoparticles (PdNPs) were generated through the biological process and exhibited for the catalytic degradation of azo dye. The palladium nanoparticles (PdNPs) were synthesized by using the cell-free approach i.e. extract of fungal strain Rhizopus sp. (SG-01), which significantly degrade the azo dye (methyl orange). The amount of catalyst was optimized by varying the concentration of PdNPs (1mg/mL to 4mg/mL) for 10 mL of 50 ppm methyl orange (MO) dye separately. The time dependent study demonstrates the biogenic PdNPs could effectively degrade the methyl orange dye up to 98.7% with minimum concentration (3mg/mL) of PdNPs within 24h of reaction. The long-term stability and effective catalytic potential up to five repeated cycles of biogenic PdNPs have good significance for acceleration the degradation of azo dyes. Thus, the use of biogenic palladium nanoparticles for dye degradation as outlined in the present study can provide an alternative and economical method for the synthesis of PdNPs as well as degradation of azo dyes present in wastewater and is helpful to efficiently remediate textile effluent.

Bio‐Fabricated Silver Nanoparticles for Catalytic Degradation of Toxic Dyes and Colorimetric Sensing of Hg2+

AbstractIn the present study, silver nanoparticles were synthesized via green synthesis using fenugreek (Trigonella foenum‐graecum L.) seeds of variety HM 425. The AgNPs were characterized by using UV‐Visible spectroscopy, Particle size analyzer, Field emission scanning electron microscopy coupled to Energy dispersive X‐ray spectroscopy, XRD, High resolution transmission electron microscopy and Fourier Transform Infrared Spectroscopy. The AgNPs were spherical and had an average particle size of 28 nm. The reduction of cationic dyes Methylene blue, Rhodamine B, and an anionic azo dye Methyl Orange by Sodium borohydride was used as a model reaction to investigate the catalytic ability of AgNPs. The results demonstrated an efficient catalytic dye degradation of methylene blue (95.81 %, 25 min, 0.1737±0.01 min−1), Rhodamine B (90.23 %, 15 min, 0.1388±0.01 min−1) and methyl orange (83.63 %, 39 min, 0.0412±0.002 min−1). The synthesized AgNPs had an excellent detection limit of 12.50 μM for Hg2+, making them excellent solid bio‐based sensors for mercury sensing.

Theoretical-experimental study of Fe–ZrO2 and Co–ZrO2. Oxidative degradation of methyl orange azo dye

In recent years, advanced oxidation processes (AOPs) based on the generation of sulfate radicals (SO4●-) (SR-AOPs) have emerged as an innovative method for the decontamination of water and wastewater. In this study, Fe(II) and Co(II) catalysts supported on ZrO₂ were synthesized and employed as an activator for PMS and PS for the degradation of methyl orange. The general objective is to gain detailed insight into the interaction between oxidants and supported metal catalysts at the molecular level. Experimental results and density functional theory (DFT) calculations were employed to analyze the potential activation mechanism of the oxidants. The support was prepared via coprecipitation, and metal ion deposition was achieved through incipient wetness impregnation. The characterization of the catalysts was conducted through atomic absorption spectrometry, X-ray diffraction and Fourier-transform infrared spectroscopy. The findings indicated that PMS was the most efficient oxidant, with Co–ZrO2 emerging as the most effective catalyst (77% MO mineralization), compared to Fe–ZrO2, which exhibited a lower degree of mineralization (37.6%) under the specified experimental conditions. The use of PS as an oxidant resulted in low levels of degradation for both catalysts. The remarkable catalytic efficacy of the Co–ZrO₂/PMS system was elucidated through the application of density functional theory (DFT) calculations. These revealed that the adsorption energy of the oxidants on Co–ZrO₂ is lower than that on Fe–ZrO₂, which could facilitate the subsequent release of radicals to the reaction medium.

Macroporous p-SnO/n-SnO2 heterojunction photocatalysts via dealloying and thermal oxidation of immiscible Sn30Zn70 precursors to boost photodegradation

Controlled synthesis of macroporous tin photocatalyst with a SnOx surface layer (SnOx@P-Sn) was achieved via chemical dealloying then thermal oxidation. The microstructure of macroporous Sn was inherited from the immiscible Sn30Zn70 precursor. The chemical composition of surface SnOx and the concentration of oxygen vacancies on the Sn ligaments is dependent on the thermal oxidation temperature, with p-SnO/n-SnO2 heterojunctions being formed at 500°C. The obtained SnOx@P-Sn@500°C p-n heterojunction surface layer achieved an outstanding degradation efficiency of 96.7 % when used to catalyze the photodegradation of methyl orange azo dyes (MO). The Langmuir-Hinshelwood Kinetics model was modified to describe the photodegradation process with higher coefficient of determination. The reason for the superior degradation reaction rates of SnOx@P-Sn@500°C p-n heterojunction photocatalyst includes: large specific surface area of the Sn substrates, appropriate band gap formed via thermal oxidation, higher oxygen vacancies, and efficient separation of electron/hole pairs in the p-SnO/n-SnO2 heterojunction.

Investigating the optimum conditions for azo dye (methyl orange and methyl red) decolorization from aqueous solution using oyster mushroom (Pleurotus ostreatus): a mycoremediation approach

Since conventional dye removal techniques require a substantial amount of energy and chemicals, this study evaluated the utilization of Pleurotus ostreatus, a species of fungus, in an environmentally beneficial mycoremediation approach to decolorize two azo dyes, methyl orange (MO) and methyl red (MR), in a liquid medium. Pleurotus ostreatus was utilized under standard circumstances in the solutions containing 0.05% (w/v) MO and 0.05% (w/v) MR, without undergoing any genetic modifications. By analyzing the effects of time (6, 12, and 18 days), temperature (15 °C to 40 °C), pH (4 to 7), and inoculum volume (1 to 25 mL) on the decolorization rate of P. ostreatus, the ideal environment for the decolorization of MO and MR was determined. The highest rate of decolorization was evident at 25 °C temperature, pH 7 within 18 days of incubation, P. ostreatus could decolorize 0.05 g MO up to 97% when added in 10 mL inoculum volume on the other hand 0.05 g MR up to 93% in 15 mL inoculum volume at pH 6. Furthermore, the dye uptake rate after 18 days for MO was 59.25% and MR was 53.97% which indicated that P. ostreatus had a better uptake efficiency for MO than MR. Based on its ability to decolorize both MO and MR under suitable circumstances, the study concludes that P. ostreatus offers an appreciable mycoremediation approach for removing dye pigments from industrial wastewater.

Facile synthesis of copper nitroprusside chitosan nanocomposite and its catalytic reduction of environmentally hazardous azodyes

One of the biggest issues affecting the entire world currently is water contamination caused by textile industries’ incapacity to properly dispose their wastewater. The presence of toxic textile dyes in the aquatic environment has attracted significant research interest due to their high environmental stability and their negative effects on human health and ecosystems. Therefore, it is crucial to convert the hazardous dyes such as methyl orange (MO) azo dye into environmentally safe products. In this context, we describe the use of Copper Nitroprusside Chitosan (Cu/SNP/Cts) nanocomposite as a nanocatalyst for the chemical reduction of azodyes by sodium borohydride (NaBH4). The Cu/SNP/Cts was readily obtained by chemical coprecipitation in a stoichiometric manner. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FT-IR) spectroscopy were applied to investigate chemical, phase, composition, and molecular interactions. Additionally, Scanning electron microscope (SEM) was used to examine the nanomaterial's microstructure. UV–vis spectroscopy was utilized for studying the Cu Nitroprusside Chitosan's catalytic activity for the reduction of azodye. The Cu/SNP/Cts nanocomposite demonstrated outstanding performance with total reduction time 160 s and pseudo-first order constant of 0.0188 s−1. Additionally, the stability and reusability study demonstrated exceptional reusability up to 5 cycles with minimal activity loss. The developed Cu/SNP/Cts nanocomposite act as efficient nanocatalysts for the reduction of harmful Methyl orange azodye.

Novel amino-ethyl carboxymethyl cellulose crosslinked ampholyte hydrogel development for Methyl orange removal from waste water

In the modern era, with the rapid growth of various industries, the issues of energy crisis and environmental pollution have garnered increasing attention. One significant source of industrial pollution is printing and dyeing wastewater. This wastewater often contains dyes that have aromatic structures and azo groups, such as Methyl orange (MO), which are both toxic and difficult to degrade. If these dyes are released into the wastewater stream without any treatment, they can have adverse effects on ecological balance and human health. Therefore, it is crucial to identify suitable treatment strategies to efficiently remove dyes from wastewater systems before discharge. In this study, the Methyl orange (MO) azo dye has been removed from dyes-contaminated wastewater, for the first time, using a novel amino-ethyl carboxymethyl cellulose crosslinked ampholyte hydrogel (AECMC). Different characterization methods, including FTIR, TGA, and DSC were used to characterize the generated AECMC compounds. The water absorption and cationic exchange capacities were assessed. Factors affecting the MO anions adsorption including MO concentration, adsorption pH, temperature, time, adsorbent dose, and agitation speed have been investigated. Moreover, the kinetics of the adsorption process was assessed by the use of three models: pseudo-first-order, Pseudo-second-order, and Elovich. Moreover, the mechanism of the adsorption process was monitored using the Intraparticle diffusion and Boyd models. Additionally, the adsorption isotherm was examined using established models such as Langmuir, Freundlich, and Temkin isotherms. The thermodynamic characteristics of the MO adsorption process have been investigated at various adsorption temperatures using the Van't Hoff model. The results obtained from the study indicate that the process of MO adsorption adhered to the Pseudo-second-order kinetic model, the Langmuir isotherm model was found to be applicable, and spontaneous and exhibited an endothermic character. In conclusion, the developed novel amino-ethyl carboxymethyl cellulose crosslinked ampholyte hydrogels (AECMC) have successive in the removal of the MO anionic dye from contaminated wastewater.

Hybrid rGO/Fe3O4 magnetic nanocomposite for anionic and cationic dye removal application

The adsorption removal of anionic and cationic azo dyes with magnetic nanoparticles was an important technological strategy for the purification of dye-contaminated water. The present work highlights the dye adsorption properties of the solvothermally synthesized hybrid reduced graphene oxide‑iron oxide (rGO/Fe3O4) nanocomposite for the efficient adsorption of methyl orange, congo red, metanil yellow, and methylene blue from the aqueous medium. Morphology, and porous characteristics of the material was analysed with FESEM and BET respectively. The magnetic properties of the material viz. M-H, FC, and ZFC were investigated with SQUID-VSM. The BET analysis confirmed the mesoporous structure of the hybrid rGO/Fe3O4 nanocomposite, with a BET-specific surface area of 27.74 m2/g. Dye adsorption experiments of hybrid rGO/Fe3O4 nanocomposite were conducted to analyse the influence of adsorbent dosage, dye concentrations, and pH variations. FTIR spectroscopy was also used to verify the adsorption of azo dyes onto the surface of the rGO/Fe3O4 nanocomposite. Hybrid rGO/Fe3O4 nanocomposite show complete adsorption of methyl orange, congo red, metanil yellow, and methylene blue dyes with adsorption capacities of 58.76, 100.3, 533, and 50 mg/g, respectively in the water medium. Hybrid rGO/Fe3O4 nanocomposite showed excellent adsorption of metanil yellow dye. The adsorbed azo dyes methyl orange, metanil yellow, methylene blue, and congo red by the rGO/Fe3O4 nanocomposite can be easily desorbs from the material indicating its reusability. The magnetic coercivity of the material at 300K was 47.4 Oe, as a result the adsorbent material can be magnetically separated from the purification system. The adsorption process of methyl orange, congo red, metanil yellow, and methylene blue dyes on the rGO/Fe3O4 nanocomposite best fits to the pseudo-second-order kinetics and the Langmuir isotherm model.

Assessment of Biodegradation and Phytotoxicity of Azo Dyes Methyl Orange and Crystal Violet by Escherichia coli and Bacillus subtilis

Azo dyes are widely used colourants, possess array of colours and are generally recalcitrant to microbial degradation. This study aimed to isolate azo dyes degrading bacteria from soil; treat methyl red and crystal violet dyes using the isolates, and assess the phytotoxicity of the treated and untreated dyes on sorghum. Ten bacteria were isolated from the soil, of which two were identified as efficient azo dyes degrading bacteria by efficiency in dye decolouration. The isolates were identified as Escherichia coli and Bacillus subtilis based on their biochemical characteristics. The isolates were able to degrade methyl orange dye by 16-75 % and crystal violet by 16-78%, depending on the concentration of the dye. The isolates were more efficient at degrading the dyes at a low concentration of 0.00025 mg/ml, as indicated by a higher percentage of decolourization (53-79%). The percentage phytotoxicity of the untreated methyl red ranged from 33-59%, while the toxicity of the untreated crystal violet ranged from 62-91%. The toxicity of the treated methyl red ranged from 9-34%, while the toxicity of the treated crystal violet ranged from 12-32%. The results revealed that the isolates were capable of degrading methyl red and crystal violet dyes, and could be useful in the bioremediation of azo dyes polluted soil.

Ultrafast catalytic reduction of organic pollutants using ternary zinc–copper–nickel layered double hydroxide

Water is the utmost essential commodity for the support of life process in animals. In recent decades, rapid industrialization and uncontrolled agricultural practices have led to increased level of toxic pollutants in groundwater, including organic pollutants (dyes, nitroarene compounds, antibiotics, etc.), inorganic pollutants (heavy metals, nanoparticles, etc.), and pesticides, posing a serious threat to human health and the environment. Although various technologies such as adsorption, photocatalysis, reverse osmosis, filtration, sedimentation, flocculation, and precipitation are available for the elimination of toxic pollutants from wastewater, issues such as their cost and efficacy limit their usage. Recently, catalysis has been found to be the most effective approach since it exhibits significant capability to eliminate almost all the pollutants and offers the benefit of simple design and low initial cost. In the present study, ternary zinc–copper–nickel layered double hydroxide (ZnCuNi‐LDH) synthesized using facile acid hydrolysis method was employed as an efficacious heterogeneous catalyst for the reduction of NACs (para‐nitrophenol and para‐nitroaniline) and degradation of organic azo dyes (methyl orange, amaranth, and brilliant black). ZnCuNi‐LDH exhibited superior catalytic activity for the reduction of all five model pollutants with reduction efficiency of more than 95% within a short time span of 5 min. Therefore, keeping in view the layered structure, high specific surface area, and remarkable catalytic performance, ZnCuNi‐LDH holds immense potential for the large‐scale catalytic degradation of refractory pollutants.

Degradation of methyl orange by the Fenton-like reaction of pyrite-activated hydrogen peroxide forming the Fe(III)/Fe(II) cycle

In this study, the typical azo dye methyl orange (MO) was degraded by pyrite (FeS2) activated by hydrogen peroxide (H2O2). When [MO] = 0.1 mM, [FeS2] = 2.0 g/L and [H2O2] = 22 mM, 96.4% MO was removed in 120 min and the TOC removal rate was higher than 50%. HO• was the primary radical responsible for MO degradation. In addition, the acid condition promoted the degradation of MO in the FeS2/H2O2 system. MO in tap water and river water was not effectively degraded, whereas acidification could weaken the inhibitory effect on the FeS2/H2O2 system to enable the degradation of MO in tap and river water. The OD600 indicated that the solution was environmentally friendly after the reaction, and three degradation pathways of MO were discussed. In summary, Fe(II) could be dissolved from FeS2, which activated H2O2 to generate Fe(III) and HO•. FeS2 could reduce Fe(III) into Fe(II), thus realizing the Fe(III)/(II) cycle and efficiently activating H2O2 to degrade MO.

Unraveling of Tectona grandis reduced palladium nanoparticles decorated on Mg-Al layered double hydroxide as an efficient nanocatalyst for cross-coupling reactions and azo dye degradation

An eco-friendly approach for encapsulating active noble metal nanoparticles (NPs) onto inert support materials and utilizing these nanocatalysts with confined approaches is paving the way for betterment. This paper provides a brief explanation for implementing a biogenic protocol for fabricating palladium nanoparticles (Pd NPs) onto Mg-Al layered double hydroxide (Mg-Al-LDH) using Tectona grandis leaves extract (TGLE) as capping and reducing agents to develop Mg-Al-LDH@TGLE Pd nanocatalyst. The structural and chemical features of the developed nanocatalyst are well characterized by different spectroscopic and analytical techniques. Owing to the significance of Pd NPs in cross-coupling reactions, the Mg-Al-LDH@TGLE Pd nanocatalyst was examined for its catalytic performance in the Hiyama and denitrogenative cross-coupling reactions for the formation of biaryls. Further, the nanocatalyst demonstrated great proficiency in the degradation of the azo dye methyl orange (MO). The Mg-Al-LDH@TGLE Pd nanocatalyst gave pronounced results with good stability and selectivity for both reactions with recyclability up to four cycles. This study presents a greener approach avoiding complicated methodologies for support materials and their advances in catalytic reactions.

Nonlinear Optical Refraction and Absorption Features of Methyl Orange Dye in Polar Solvents.

Herein, we report the nonlinear optical (NLO) refraction and absorption features of azo dye namely, methyl orange (MO) dissolved in ethanol, methanol, acetone, 1-propanol, DMF and DMSO. The UV-Visible absorption study reveals that the maximum absorption spectrum of MO dye appeared towards longer wavelength by increasing the solvent polarizability is the result of red shift or bathochromic shift. The Z-scan method is utilized to measure the third-order NLO features of MO dye in different polar solvents. A continuous wave laser with 5-mW power and an excitation wavelength of 405nm is employed in the Z-scan technique. The NLO features including nonlinear index of refraction (n2), nonlinear coefficient of absorption (β) and third-order NLO susceptibility (χ3) are calculated to be the order of 10-7 cm2/W, 10-2cm/W and 10-7 esu, respectively. The NLO index of refraction shows peak-valley transmittance is the result of self-defocusing and NLO absorption coefficient exhibits both positive and negative nonlinearity owing to saturable absorption (SA) and reverse saturable absorption (RSA). The effect of solvent polarizability and dipole moment on third-order NLO susceptibility of MO dye is discussed. Based on the experimental results, an azo dye MO appears to be a promising option for NLO applications in the future.

Advanced Photodegradation of Azo Dye Methyl Orange Using H2O2-Activated Fe3O4@SiO2@ZnO Composite under UV Treatment.

The Fe3O4@SiO2@ZnO composite was synthesized via the simultaneous deposition of SiO2 and ZnO onto pre-prepared Fe3O4 nanoparticles. Physicochemical methods (TEM, EDXS, XRD, SEM, FTIR, PL, zeta potential measurements, and low-temperature nitrogen adsorption/desorption) revealed that the simultaneous deposition onto magnetite surfaces, up to 18 nm in size, results in the formation of an amorphous shell composed of a mixture of zinc and silicon oxides. This composite underwent modification to form Fe3O4@SiO2@ZnO*, achieved by activation with H2O2. The modified composite retained its structural integrity, but its surface groups underwent significant changes, exhibiting pronounced catalytic activity in the photodegradation of methyl orange under UV irradiation. It was capable of degrading 96% of this azo dye in 240 min, compared to the initial Fe3O4@SiO2@ZnO composite, which could remove only 11% under identical conditions. Fe3O4@SiO2@ZnO* demonstrated robust stability after three cycles of use in dye photodegradation. Furthermore, Fe3O4@SiO2@ZnO* exhibited decreased PL intensity, indicating an enhanced efficiency in electron-hole pair separation and a reduced recombination rate in the modified composite. The activation process diminishes the electron-hole (e-)/(h+) recombination and generates the potent oxidizing species, hydroxyl radicals (OH˙), on the photocatalyst surface, thereby playing a crucial role in the enhanced photodegradation efficiency of methyl orange with Fe3O4@SiO2@ZnO*.

Merits of photocatalytic activity of synthesized (ZnxCu(1−x)Fe2O4); x = (0–1) magnetic nanoparticles for wastewater treatment

Synthesis of crystalline zinc copper ferrite nanoparticles was achieved via a simple co-precipitation method. Scanning electron microscope (SEM) is utilized to give the morphological characterization of the prepared samples. A transmission electron microscope (TEM) was employed for further identification and confirmation of the particle size and morphology. Moreover, X-ray diffraction (XRD) and Fourier transformation infrared (FTIR) spectroscopy were utilized to examine crystalline structure and chemical structure, respectively. The photocatalytic performance of Zn0.5Cu0.5Fe2O4 nanoparticles under UV light was assessed by decolorization of methyl orange (MO) azo dye. The efficiency of photocatalytic degradation of 20 ppm of MO by Zn0.5Cu0.5Fe2O4 nanoparticles 15 mg was 96% after 135 min at an ambient temperature of 25 °C and pH value of 3. Further interpretation was carried out and a proposed mechanism for the MO photodegradation over Zn0.5Cu0.5Fe2O4 nanoparticles was suggested.

Adsorption of anionic and cationic azo dyes from wastewater using novel and effective multicomponent adsorbent

Water pollution is rising worldwide, necessitating innovative and effective treatment solutions. This study introduces a multicomponent/multifunctional novel nanocomposite synthesized from polyethyleneimine (PEI), graphene oxide (GO), bentonite clay, and MgFeAl-layered triple hydroxide (LTH), termed as AGO/Bentonite/LTH. In this study, the synthesized AGO/Bentonite/LTH nanocomposite was utilized to remove azo dyes (methyl orange and crystal violet) from contaminated water samples. The novel AGO/Bentonite/LTH nanocomposite was benchmarked against its pristine materials and their binary combinations. The results indicated the superior adsorption performance of the AGO/Bentonite/LTH nanocomposite relative to all other adsorbents synthesized and examined herein. All the synthesized adsorbents were characterized using different techniques in order to reveal their textural properties, functional groups, morphology, thermal stability, and crystallinity before applying them to decontaminate wastewater samples contaminated with methyl orange (MO) and crystal violet (CV). The Langmuir adsorption isotherm model predicted that the maximum adsorption capacities of CV and MO onto the AGO/Bentonite/LTH nanocomposite are 1705.1 and 1171.8 mg/g, respectively. On the other hand, zeta potential, pH, and FTIR studies suggested the existence of multiple mechanisms governing the adsorption of CV and MO onto the AGO/Bentonite/LTH nanocomposite. Thermodynamic results indicated the endothermicity and exothermicity of CV and MO adsorption, respectively. Another interesting finding reported herein is the high reusability of this nanocomposite as demonstrated by the minimal reduction in the removal of these two pollutants with the repetitive use of the nanocomposite. Additionally, the nanocomposite can also be easily and cheaply regenerated via a few rinses with a diluted NaOH aqueous solution. These interesting observations suggest that the synthesized AGO/Bentonite/LTH nanocomposite is a potent material for efficient dye removal from contaminated water bodies.

Research Progress on Photocatalytic Degradation of Methyl Orange Dye Wastewater by Light‐assisted Composite‐modified Ag3PO4

AbstractA new type of modified catalyst was prepared by a silver ammonia‐assisted precipitation method through a custom‐built electrochemical reactor, and the catalytic degradation of the azo dye methyl orange was studied under the synergistic effect of visible light. The optimum doping ratio for the loading of graphene oxide (GO) is 1.0 %. Under the optimum conditions, the degradation rate of Ag3PO4/GO/NiFe2O4 to methyl orange is 97.56 % when the light reaction time is 50 min. After three cycles, the degradation rate of methyl orange by Ag3PO4/GO/NiFe2O4 is 94.47 %. Through the free radical capture experiment, it is known that the contribution degree of the main active substances in the photocatalytic degradation of methyl orange is h + >⋅O2− >⋅OH. By forming a Z‐type heterojunction between Ag3PO4 and NiFe2O4, the recombination probability of photogenerated carriers is greatly reduced, and the stability of Ag3PO4 is improved.

Development of novel amino-ethyl chitosan hydrogel for the removal of methyl orange azo dye model

The present study introduces a new and straightforward method for the amination of Chitosan. This method involves coupling Chitosan (CS) with 2-chloroethylamine (ENH2) in a single step to produce an amino-ethyl Chitosan derivatives with increased amine group content (CS-ENH2) using click chemistry. The resulting derivatives were then crosslinked using Glutaraldehyde to form amino-ethyl Chitosan Schiff bases. The novel amino-ethyl Chitosan Schiff bases were subsequently utilized as adsorbents for the removal of Methyl Orange (MO) dye from aqueous solutions using a batch technique, and the performance of the produced Schiff bases was compared with that of the native Chitosan Schiff base. The CS-ENH2 adsorbents show improved adsorption capacity up to 300% of the native Chitosan Schiff base with almost double removal rate. The adsorption temperature has a positive impact in general while almost 100% of MO removed at 60 °C using CS-ENH2 adsorbents compared with 66% of the native Chitosan Schiff base adsorbent. The adsorption pH shows a negative impact on the MO removal percent. That effect reduced sharply using the CS-ENH2 adsorbents with higher amination degree while the MO removal percent almost being constant over a wide range of pH; 2.0–7.0. The agitation speed has the same positive effect over all the adsorbents. However, the rate of MO removal percent decreased with increase the agitation speed up to 250 rpm. The experimental findings demonstrated that the highest percentage of MO dye removal was achieved under the conditions of pH 2.0, a temperature of 60 °C, agitation speed of 250 rpm, and adsorption duration of 90 min. These Schiff bases were subsequently characterized using advanced analytical techniques including Fourier Transform Infrared spectroscopy, Thermal analysis (TGA and DSC), and Scanning Electron Microscopy.

Novel amino-ethyl Chitosan hydrogel for methyl orange removal from waste water: Kinetics, isotherms, and thermodynamics studies

The Methyl orange (MO) azo dye has been removed from dyes-contaminated wastewater for the first time using a novel amino-ethyl Chitosan crosslinked hydrogel (CS-ENH2). The induced amine groups served as positive charge centers to bind MO azo-dye anions. The MO adsorbents' capabilities in comparison to native Chitosan (CS) are directly correlated positively with the amination phase which a very rapid initial adsorption was seen in the first 60 min, then began to slow until it leveled off after 120 min and 180 min for CS and CS-ENH2. The adsorption temperature has a positive effect, particularly at low temperatures, between 25 °C and 30 °C, where the adsorption capacity of the CS-ENH2 is double that of the CS, while at higher temperatures that effect diminished. The kinetics, isotherms, and thermodynamics characteristics of the MO adsorption process were followed. The obtained results showed that the MO adsorption process adhered to the pseudo-second-order kinetic model, the Langmuir isotherm model, and had an endothermic and spontaneous character with a maximum adsorption Langmuir monolayer of 3.66 and 10.53 mg/g for CS and CS-ENH2. In conclusion, the CS-ENH2 adsorbent removed up to 2.86 folds of MO amount of that removed using Chitosan under the same operating conditions, which reflected in the reduction of the used adsorbent amount, adsorption time, and finally proved the cost-effective of the developed CS-ENH2 adsorbent.