Congo Red Research Articles

Elucidating the photocatalytic mechanism of biomass-derived carbon dots nanocomposite for efficient degradation of MB and CR dyes: Insights into protein binding applications

This study introduces an environmentally sustainable method for synthesizing a nanocomposite using carbon quantum dots derived from green tea waste and zinc oxide. The single-step hydrothermal process not only addresses waste management but also yields a versatile nanocomposite with diverse applications. Rigorous characterization reveals its morphology, crystallinity, phase identification, structural behavior, optical properties, and chemical composition. Incorporating carbon quantum dots into the zinc oxide matrix reduces the band gap to 1.87 eV, enhancing charge separation and light-harvesting. This modification significantly boosts photocatalytic activity, achieving degradation efficiencies of 95.16 % for methylene blue (MB) and 93.21 % for congo red (CR) under visible light. The effects of pH, contact time, and photocatalyst concentration on dye degradation were explored. The nanocomposite, exhibiting both adsorption and photocatalytic performance, is poised for broad applications. Fluorescence quenching studies with lysozyme protein provide insights into potential applications across diverse fields, highlighting its environmentally friendly and multifunctional attributes.

Fabrication of novel N-rich g-C3N5 decorated cubic spinel Co2SnO4 hybrids: Studies on morphology, degradation efficacy, pathway and mechanism

Managing interfacial charge transfer is a crucial and challenging problem in promoting the migration/separation of photogenerated carriers for heterojunction photocatalysts. The innovative dual Z-scheme heterojunction is crucial in effectively removing organic pollutants by enhancing the separation of charge carriers. A novel Co2SnO4/g-C3N5 (CoSn/CN) nanocomposite heterojunction is synthesized using a simple hydrothermal approach. The resulting nanocomposite is then studied in terms of its crystal phases, optical characteristics, surface morphologies, and compositions. The charge separation efficiency is significantly enhanced, resulting in a high-efficiency photocatalytic degradation performance. The CoSn/CN photocatalyst exhibits a degradation efficiency of 99.11 % and 98.08 % for Congo red (CR) and Rose Bengal (RB) respectively, within 75 minutes and 50 minutes under visible light conditions. In addition, scavenging tests demonstrated the generation of active radical species, specifically •OH, h+, and •O2−. The hypothesized CR and RB degradation process and potential pathways were derived from the proper experimental study. The primary objective of this project is to create a novel photocatalytic material that can effectively degrade dyes. Additionally, the study aims to construct a larger-scale photocatalytic system, determine the cost of the wastewater treatment unit, and analyze the life cycle of the entire process. In addition, the Co2SnO4/g-C3N5 heterojunction also demonstrates the expected stability as no substantial drop was observed after 5 cycles. The exceptional degrading performance and stability of the system can be attributed to the enhanced separation of photo-induced charge carriers and the strong contact at the interface, achieved through the formation of a Z-Scheme charge transfer.

Lead Oxide Modified Graphite Electrodes for Electrochemical Degradation of Congo Red Dye in Aqueous Solution

Lead Oxide Modified Graphite Electrodes for Electrochemical Degradation of Congo Red Dye in Aqueous Solution

Activated Iron-Porous Carbon Nanomaterials as Adsorbents for Methylene Blue and Congo Red.

The adsorption properties of microporous carbon materials modified with iron citrate were investigated. The carbon materials were produced based on resorcinol-formaldehyde resin, treated in a microwave assisted solvothermal reactor, and next carbonized in the tube furnace at a temperature of 700 °C under argon atmosphere. Iron citrate was applied as a modifier, added to the material precursor before the synthesis in the reactor, in the quantity enabling to obtain the nanocomposites with C:Fe mass ratio equal to 10:1. Some samples were additionally activated using potassium oxalate or potassium hydroxide. The phase composition of the produced nanocomposites was determined using the X-ray diffraction method. Scanning and transmission electron microscopy was applied to characterize the changes in samples' morphology resulting from the activation process and/or the introduction of iron into the carbon matrix. The adsorption of nitrogen from gas phase and dyes (methylene blue and congo red) from water solution on the obtained materials was investigated. In the case of methylene blue, the adsorption equilibrium isotherms followed the Langmuir isotherm model. However, in the case of congo red, a linear dependency of adsorption and concentration in a broad equilibrium concentration range was found and well-described using the Henry equation. The most efficient adsorption of methylene blue was noticed for the sample activated with potassium hydroxide and modified with iron citrate, and a maximum adsorption capacity of 696 mg/g was achieved. The highest congo red adsorption was noticed for the non-activated sample modified with iron citrate, and the partition coefficient for this material equaled 171 dm3/g.

Harnessing the hidden environmental power of Bjerkandera adusta laccase: Sustainable production, green immobilization, and eco-friendly decolorization of mixed azo dyes

This research unveils the untapped potential of laccase, derived from the Bjerkandera genus, utilizing it in an immobilized system aimed at detoxifying harmful azo dye effluents from the textile industry, thus contributing to environmental protection. Marking a pioneering achievement, we recorded the highest laccase activity at 94.52 U/g cultivating B. adusta's mycelium on brewer's spent grain, enhanced with lignocellulosic waste, under meticulously optimized conditions −2.69 g of alkali-pretreated beech sawdust, 0.91 g of cypress cone, and 8-day incubation period. The harvested laccase was subjected to an immobilization process on alkali-pretreated beech sawdust, where, through optimization, we established the ideal conditions (30 mg of carrier, pH 7, and 3.5 h), achieving an immobilization efficiency of 72.24% with a residual activity of 57.64%. Remarkably, both free and immobilized forms of the B. adusta TMF1 laccase enzyme demonstrated formidable efficacy in decolorizing a mix of three distinct azo dyes (Orange G, Eriochrome Black T, and Congo Red), eliminating over 63% of the coloration within just 30 min. The immobilized laccase showed consistent performance across four decolorization cycles. Moreover, the breakdown products of the azo dye mix were analyzed using the HPLC method, complemented by evaluations of potential antimicrobial activity, phytotoxicity and cytotoxicity, revealing a non-toxic composition without cytotoxicity, highlighting the process's safety for environmental release. The significance of this research is reflected in the distinguished construction of a green biocatalyst acting as a stable and time-efficient in remediation of targeted azo dye pollution from the textile industry following the principles of circular economy.

Porous Metal Organic Framework (MOF) derived dimorphic (n-ZnO/p-NiO) Z-scheme heterojunction anchored with MWCNTs (ternary nano-architecture): A novel approach for optimization of photodegradation mechanism and kinetics of Congo red (CR) dye

Global efforts to combat water pollution, especially from organic dyes like Congo red, emphasize the use of advanced nanomaterials for sewage purification. Metal-Organic Frameworks (MOFs), known for their crystalline structures and versatile properties, have become pivotal in wastewater treatment research. Integrating MWCNTs into MOF derived composite nanostructures is a strategic advancement, boosting the efficiency of photocatalytic systems and addressing environmental concerns. This study details the synthesis of a novel Z-scheme heterojunction nanocomposite (n-ZnO/p-NiO) incorporating multi-walled carbon nanotubes (MWCNTs), achieved via a solvothermal method using metal-organic framework (MOF) as a template. The study uses XRD, FTIR, FESEM, BET, UV, and PL for comprehensive nanocomposite characterization, offering insights into its structural, morphological, and optical properties. The resultant nanocomposite displays high surface area, sturdy pore arrangement, and consistent morphology. MWCNTs influence crystal growth and optical absorption, enhancing surface hydroxyl group concentration and acting as electron acceptors. This results in decreased photo oxidation and improved overall stability under light exposure in the composite. The composite achieves 92 % Congo red degradation in 60 min under UV light, showcasing superior dye adsorption capacity. This underscores its potential as an efficient photocatalyst for environmental remediation and wastewater treatment.

Lanthanide Complexes Based on Rigid Benzimidazole Carboxylic Acid Ligand: Sensing of Nitrobenzene, Fe(III) Ions, and Adsorption of Dyes

ABSTRACTFive new lanthanide complexes {[Sm(H2L)(H2O)4(Cl)]⋅H2O⋅Cl}n (1), {[Eu(H2L)(H2O)4Cl]⋅Cl}n (2), {[La(H2L)(H2O)4Cl]⋅Cl}n (3), {[Pr(H2L)(H2O)4Cl]⋅Cl}n (4), {[Ce(H2L)(H2O)4Cl]⋅Cl}n (5) (H3L = 2‐hydroxy‐5‐(5‐(hydroxy‐λ2‐methoxy)‐1H‐benzo[d]imidazole‐5‐carboxylic acid) were successfully synthesized under solvothermal method. 1 exhibits a two‐dimensional (2D) network structure, whereas 2–5 feature one‐dimensional (1D) chain structure. The fluorescence investigations demonstrated that 1–5 could be the fluorescent sensor for nitrobenzene (NB) and Fe(III) ions with high selectivity, sensitivity, and low detection limits. Furthermore, 1–5 displayed the good adsorption to anionic dye Congo red (CR), and the adsorption capacities were 140.5, 206.5, 212.5, 111.5, and 211.5 mg·g−1, respectively.

Recent Advances in Utilizing Lignocellulosic Biomass Materials as Adsorbents for Textile Dye Removal: A Comprehensive Review.

This review embarks on a comprehensive journey, exploring the application of lignocellulosic biomass materials as highly effective adsorbents for the removal of textile dyes (cationic and anionic dyes) from wastewater. A literature review and analysis were conducted to identify existing gaps in previous research on the use of lignocellulosic biomass for dye removal. This study investigates the factors and challenges associated with dye removal methods and signifies their uses. The study delves into the pivotal role of several parameters influencing adsorption, such as contact time, pH, concentration, and temperature. It then critically examines the adsorption isotherms, unveiling the equilibrium relationship between adsorbent and dye and shedding light on the mechanisms of their interaction. The adsorption process kinetics are thoroughly investigated, and a detailed examination of the adsorbed rate of dye molecules onto lignocellulosic biomass materials is carried out. This includes a lively discussion of the pseudo-first, pseudo-second, and intra-particle diffusion models. The thermodynamic aspects of the adsorption process are also addressed, elucidating the feasibility and spontaneity of the removal process under various temperature conditions. The paper then dives into desorption studies, providing insights into the regeneration potential of lignocellulosic biomass materials for sustainable reusability. The environmental impact and cost-effectiveness of employing lignocellulosic biomass materials in textiles including Congo Red, Reactive Black 5, Direct Yellow 12, Crystal Violet, Malachite Green, Acid Yellow 99, and others dyes from wastewater treatment are discussed, emphasizing the significance of eco-friendly solutions. In summary, this review brings together a wealth of diverse studies and findings to present a comprehensive overview of lignocellulosic biomass materials as adsorbents for textile cationic and anionic dye removal, encompassing various aspects from influential parameters to kinetics, adsorption isotherms, desorption, and thermodynamics studies. Its scope and other considerations are also discussed along with its benefits. The collective knowledge synthesized in this paper is intended to contribute to the advancement of sustainable and efficient water treatment technologies in the textile industry.

Eco-friendly plant extract-assisted fabrication of CeO2@CH@Ag nanocomposite: A heterogeneous catalyst for organic pollutant remediation

This study explores the synthesis and application of a novel cerium oxide-chitosan-silver (CeO2@CH@Ag) nanocomposite as an efficient catalyst for the reduction of organic pollutants, including methyl orange (MO), congo red (CR), and 4-nitroaniline (4-NA). The nanocomposite was synthesized via a co-precipitation method, followed by in-situ deposition of silver nanoparticles on its surface. Comprehensive characterization techniques, including FTIR, XRD, FESEM, EDX, XPS and nitrogen sorption measurements, confirmed the successful incorporation of CeO₂ and silver within the chitosan matrix. The CeO2@CH@Ag nanocatalyst exhibited a high surface area of 58.081 m2/g, exhibiting remarkable catalytic activity, facilitating rapid reduction of the organic pollutants within 6 min using sodium borohydride as a reducing agent. Kinetic studies revealed pseudo-first-order reaction kinetics, with rate constants of 1.09, 0.38, and 0.58 min⁻1 for MO, CR, and 4-NA, respectively. The proposed mechanism involves the adsorption of dye molecules onto the catalyst's porous surface, followed by electron transfer from the reducing agent to the dye, facilitated by the redox properties of CeO2 and silver. The CeO2@CH@Ag nanocatalyst demonstrates the promising potential for efficient wastewater treatment and remediation of organic pollutants.

Enhancing the Degradation of All Moieties of the Environment Pollutant Congo Red Dye in Dark, White Light, and Solar Light by using CuS Nanoflowers: A Quantita tive Analysis

Enhancing the Degradation of All Moieties of the Environment Pollutant Congo Red Dye in Dark, White Light, and Solar Light by using CuS Nanoflowers: A Quantita tive Analysis

TiO2/Ti3C2Tx gel microsphere for efficient photocatalytic degradation of organic pollutant with excellent recycling stability

Enhancing the recycling stability of photocatalysts is crucial for practical applications. The significant loss of powder catalyst materials during the recycling process hampers its degradation rate and results in a low reuse rate. Herein, the in-situ prepared TiO2/Ti3C2Tx (TOTC) heterojunction is embedded in gel microsphere (GMS) as a recyclable photocatalyst TOTC@GMS for efficient photocatalytic degradation of Congo red (CR). The experimental results show that the removal rate can reach 99 % in 120 min without any co-catalysts or sacrificial reagents. The GMS can be recycled after rinsing in deionized water for only 2 min, and the removal rate still maintains over 90 % after 25 cycles. Additionally, under natural sunlight exposure, TOTC@GMS achieves a removal rate of 90 % for CR in real water samples. The degradation mechanism is elucidated through hydroxyl radicals (OH) and superoxide radicals (O2−) as the main reactive species, as confirmed by free radical scavenging and electron paramagnetic resonance (EPR) experiments. The degradation products are further analyzed using high-performance liquid chromatography-mass spectrometry (LC-MS), allowing for the deduction of degradation pathways of CR. Furthermore, a phytotoxicity test confirms the non-toxicity of the organic micromolecules generated after degradation. This study presents a practical strategy to improve the recycling stability of photocatalysts, thereby effectively reducing the cost of wastewater treatment.

Sustainable protein/polysaccharide aerogel for the simultaneous and efficient removal of multiple organic contaminants: Insights from DFT calculations and phenomenological mass–transfer modeling

Wastewater contains various organic contaminants that pose great hazards to human health and the environment. A protein/polysaccharide-derived aerogel, namely, ICMA, was developed as a high-performance adsorbent for the simultaneous and efficient removal of diverse contaminants from wastewater, including melanoidin (MLE), Congo red (CR), and diclofenac (DIC). Metal organic framework (UiO-66-NH2), as a regulatory factor, significantly improved the porosity and pore volume of the ICMA to enhance the capture performance of contaminants. The ICMA exhibited outstanding adsorption efficiency owing to the incorporation of ample polyamine functional groups and its well-developed pore structure, large porosity and pore volume, and remarkable heat resistance. The equilibrium capture capacities of the ICMA were 1364, 2031, and 539 mg/g for MLE, CR, and DIC, respectively, with corresponding removal efficiencies all exceeding 90%. Furthermore, the ICMA can capture cationic dyes through MLE/CR/DIC-bridging interactions. After five cycles, the used ICMA can still maintain a high contaminant removal rate/amount, demonstrating good reusability. The classic adsorption model showed that the capture of contaminants by the ICMA is a double-layered and heterogeneous adsorption orientation. A brand new LWAMTM model demonstrated that the adsorption mass–transfer process is jointly determined by the external mass conveyance, pore diffusion, and adsorption on the active site. Multiple characterizations indicated that the contaminant adsorption onto the ICMA was mainly facilitated by charge interactions, with H-bonds playing a secondary role. Quantum chemical theory simulations further provide insights into the atomic-level mechanisms involved in the capture of contaminants. Hirshfeld surface analysis revealed that the ICMA functions as both an H-bond acceptor and a donor during contaminant adsorption. Scale-up and upgrade adsorption were performed to treat actual/simulated wastewater, establishing the groundwork for the industrial implementation of the ICMA.

Lanthanum hydroxide@cellulose membranes with tunable pore sizes for selective removal of dyes with the same charges

Adsorptive membranes for the efficient separation of dyes with the same charges are quite desirable. Herein, a novel membrane of lanthanum hydroxide/cellulose hydrogel coated filter paper (LC) was prepared through a facile strategy of dip-coating followed by freeze-shaping. With the aid of cellulose gel, the generated La(OH)3 achieved fine dispersion. In addition, the pore size of LC membrane could be regulated by altering the cellulose concentration or the lanthanum chloride dosage, which was crucial for its water flux. In particular, the obtained membrane possessed a high water flux (128.4 L m−2 h−1) and a high dye rejection (97.2 %) for anionic Congo red (CR) only driven by the gravity, which outperformed many previously reported membranes. More intriguingly, its dye rejection for anionic methyl orange (MO) was only 0.9 %, exhibiting high selectivity for dyes with the same charges. Single-solute adsorption experiments indicated that the CR adsorption on the membrane was best fitted by the pseudo-first-order kinetic model, and it followed the Langmuir monolayer adsorption mechanism.

Synthesis, characterization, and photocatalytic activity of aluminum doped spinel ferrite nanoparticles for the photodegradation of Congo red

Synthesis, characterization, and photocatalytic activity of aluminum doped spinel ferrite nanoparticles for the photodegradation of Congo red

Removal of congo red and malachite green from aqueous solution using ternary GO/Bi2O3/MgO materials by co-precipitation method

The present work describes the preparation of Bismuth oxide and magnesium oxide modified with graphene oxide (GO/Bi2O3/MgO) using the co-precipitation method for the elimination of malachite green (MG) and congo red (CR) dyes from aqueous solution. The synthesized GO/Bi2O3/MgO materials were analyzed by using FTIR, SEM, XRD, EDX and EDS. The batch experiment was aimed to investigate the adsorption process by varying various parameters of optimum value for CR and MG dye adsorption such as adsorbent dosage was 100 mg, contact time was 30 min, stirring speed was 250 rpm, initial dye concentration was 30 mg L−1 and pH was 6.5. From experimental data, we concluded that for elimination of MG and CR dye with higher coefficient value (R2) was best fitted with the Langmuir isotherm model. The maximum adsorption capacity was observed to be 45.454 mg/g for MG and 58.823 mg/g for CR, respectively. The mechanism of the adsorbent and both the dyes were explained by electrostatic interaction, π-π interaction, and hydrogen bonding. To check the stability of the GO/Bi2O3/MgO materials, we performed the reusability study using various solvents like methanol, ethanol, water, sodium hydroxide and acetone. Among various solvents, NaOH has shown maximum desorption of both dyes.

A novel 3D hierarchical NiFe-LDH/graphitic porous carbon composite as multifunctional adsorbent for efficient removal of cationic/anionic dyes and heavy metal ions

Developing effective adsorbents for wastewater purification is crucial, as excessive emissions of toxic dyes and heavy metal ions have been proven harmful to ecosystems and human health. A NiFe-layered double hydroxide/graphitic porous carbon (NiFe-LDH/GPC) composite was fabricated by introducing NiFe-LDH nanosheets into GPC via a simple hydrothermal method to utilize the advantages of both materials fully, and thus ultimately obtain a composite adsorbent with improved adsorption properties. The samples obtained were comprehensively characterized by various characterization means, and the effects of several critical influential factors on the pollutant uptake capability of the NiFe-LDH/GPC were also studied through batch experiments. The results show that the as-synthesized NiFe-LDH/GPC exhibits a three-dimensional (3D) fluffy ultrathin-wall hierarchical porous structure, which possesses a high specific surface area and pore volume separately up to 506.74 m2/g and 0.22 cm3 g−1 as well as a relatively narrow pore size distribution. These characteristics bring advantages to enhance the adsorption ability of the NiFe-LDH/GPC for cationic/anionic dyes and heavy metal ions such as congo red (CR), malachite green (MG) and hexavalent chrome (Cr(VI), which reached the maximum adsorption capacity of 1726.51 mg/g, 1157.11 mg/g and 155.72 mg/g under the optimum conditions, respectively. Meanwhile, the adsorption behavior can be well described by the pseudo-second-order kinetic model and Langmuir isotherm model, reflecting that the sorption process mainly occurred chemically in the adsorbent monolayer. Furthermore, the NiFe-LDH/GPC maintained relatively high adsorption performance after multicycle testing, manifesting its good recyclability and stability.

Facile synthesis and optimization of Acacia senegal gum hydrogel for kinetically treated adsorptive removal of targeted industrial effluents

This context summarizes a detail on the fabrication of Acacia senegal Gum Hydrogel (ASGh) within well-engineered microemulsion, and thereafter chemical modification for environmental remediation. In brief, Divinylsulfone was used to crosslink polymeric chains and produce ASGh in ˂50 μm size within the reverse-microemulsion of Natrium-bis-(2-ethylhexyl) sulfosuccinate in gasoline. ASGh were subjected to chemical modification via versatile diethylenetriamine to produce m-[ASGh] for adsorptive removal of methyl orange (MO), eosin Y (EY) and congo red (CR) from waste-water. ASGh and m-[ASGh] were characterized through Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and zeta potential measurements. For instance, FT-IR spectra depicted new bands upon Diethylenetriamine modification. The zeta potential measurements confirm a positively charged surface of m-[ASGh] upon Diethylenetriamine addition. Interestingly, 0.05 g m-[ASGh] demonstrated 91.0, 84.1, and 73.0 % removal efficiency towards MO, EY and CR, respectively in 2 h equilibrium time. Langmuir, Freundlich and modified-Freundlich isotherms were applied to further delineate adsorption data. Modified-Freundlich model depicted comparatively more agreeable fit, and delivered R2 value nearer to unity. Further, 143 mg·g−1, 130 mg·g−1 and, 116 mg·g−1 maximum adsorption capacity (QM) was represented by m-[ASGh] towards MO, EY and CR, respectively in 2 h. Interestingly, real water sample were tested whereby, the QM against MO, EY and CR was 146 mg·g−1, 132 mg·g−1 and, 111 mg·g−1, respectively in 2 h equilibrium time. To conclude, m-[ASGh] could be treated as decolorizing agent in real waste-water polluted through negatively charged organic pollutants, particularly MO.

Laser-Assisted Preparation of TiO2/Carbon/Ag Nanocomposite for Degradation of Organic Pollutants.

The ever-increasing expansion of chemical industries produces a variety of common pollutants, including colors, which become a global and environmental problem. Using a nanocatalyst is one of the effective ways to reduce these organic contaminants. With this in mind, a straightforward and effective method for the production of a novel nanocatalyst based on lignin-derived carbon, titanium dioxide nanoparticles, and Ag particles (TiO2/C/Ag) is described. The preparation of carbon and Ag particles (in sub-micro and nano size) was carried out by laser ablation in air. The nanocomposite was synthesized using a facile magnetic stirrer of TiO2, C, and Ag. According to characterization methods, a carbon nanostructure was successfully synthesized through the laser irradiation of lignin. According to scanning electron microscope images, spherical Ag particles were agglomerated over the nanocomposite. The catalytic activities of the TiO2/C/Ag nanocomposite were tested for the decolorization of methylene blue (MB) and Congo red (CR), employing NaBH4 in a water-based solution at 25 °C. After adding fresh NaBH4 to the mixture of nanocomposite and dyes, both UV absorption peaks of MB and CR completely disappeared after 10 s and 4 min, respectively. The catalytic activity of the TiO2/C/Ag nanocomposite was also examined for the reduction of 4-nitrophenol (4-NP) using a NaBH4 reducing agent, suggesting the complete reduction of 4-NP to 4-aminophenol (4-AP) after 2.30 min. This shows excellent catalytic behavior of the prepared nanocomposite in the reduction of organic pollutants.

Sonochemical Facile Synthesis of Bismuth Oxide Nanoparticles Using Citrus Lemon Extract and Its Catalytic Activity on Azo Dye Degradation

The synthesis of bismuth oxide nanoparticles through sono-cavitation using citrus lemon extract as a simple, eco-friendly and cost-efficient method was evaluated. The aqueous extract of citrus lemon acted as a bio-reducing and capping/stabilizing agent in the single-step biosynthesis of bismuth oxide nanoparticles. Different instrumental techniques have been used to characterize the biosynthesized bismuth oxide nanoparticles, including UV–vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy (EDS). UV–vis spectroscopy revealed the formation of stable bismuth oxide nanoparticles at λmax of 400 nm with a surface plasmon resonance (SPR) band. TEM revealed that the biosynthesized bismuth oxide nanoparticles were rod shaped with a particle size of 26 nm. A potential mechanism for the formation of bismuth oxide nanoparticles with the influence of sono-cavitation has been suggested based on the observed findings. These catalytic capabilities of the bio-synthesized bismuth oxide nanoparticles were then evaluated by degradation of toxic azo dyes under different laboratory conditions. The azo dye Congo red (CR) was effectively degraded to 86% within 30 min under optimum experimental conditions using 0.12 g/mL catalyst. Thus, the phytochemical citrus lemon offers a cheap and eco-friendly solution for the synthesis of catalytic nanoparticles to degrade highly toxic organic compounds such as azo dyes.Graphical

Preparation of Functionalized Ethylene-Vinyl-Alcohol Nanofibrous Membrane Filter for Rapid and Cyclic Removing of Organic Dye from Aqueous Solution.

A functionalized ethylene-vinyl-alcohol (EVOH) nanofibrous membrane (NFM) was fabricated via co-electrospinning H4SiW12O40 (SiW12) and EVOH first, and then grafting citric acid (CCA) on the electrospun SiW12@EVOH NFM. Characterization with FT-IR, EDX, and XPS confirmed that CCA was introduced to the surface of SiW12@EVOH NFM and the Keggin structure of SiW12 was maintained well in the composite fibers. Due to a number of carboxyl groups introduced by CCA, the as-prepared SiW12@EVOH-CCA NFM can form a high number of hydrogen bonds with CR, and thus can be used to selectively absorb congo red (CR) in aqueous solutions. More importantly, the CR enriched in the NFM can be rapidly degraded via photocatalysis. SiW12 in the NFM acted as a photocatalyst, and the hydroxyl groups in the NFM acted as an electron donor to accelerate the photodegradation rate of CR. Meanwhile, the SiW12@EVOH-CCA NFM was regenerated and then exhibited a relatively stable adsorption capacity in five cycles of filtration-regeneration. The bifunctional nanofibrous membrane filter showed potential for use in the thorough purification of dye wastewater.