Red Azo Research Articles

A comparative study of Cu-based nanoparticles and their spin-coated films: photocatalytic degradation mechanisms and efficiencies towards malachite green and neutral red azo dyes.

In this work, a comparison of the photocatalytic activity of free-standing Cu-based nanoparticle mixtures and spin-coated nanoparticle films under visible-light radiation is conducted. Herein, Cu2O, Cu2O-Cu, Cu2O-Cu3N-Cu, and Cu3N-Cu nanoparticle mixtures were successfully synthesized by a non-aqueous sol-gel route and then deposited on a glass substrate by spin-coating. The surface chemistry of the nanoparticles studied by X-ray photoelectron spectroscopy (XPS) allowed elucidating the nanoparticle synthesis mechanism. The UV-Vis absorption spectroscopy illustrates that photocatalytic activity is attributed to the high specific surface of the nanoparticles and their wider absorption range region from 500 to 1100nm. Unlike the free-standing photocatalysts, the photocatalytic effect of spin-coated nanoparticle films enabled their facile reclamation, which solves a key issue for practical applications of the photocatalysts. The photocatalytic performances on neutral red and malachite green organic dyes were influenced by the type of visible light sources, i.e., solar simulator and natural sunlight. The results indicate that photodegradation efficiency is the highest for Cu2O nanoparticles, reaching values of 82% for neutral red and 94% for malachite green. We also demonstrate that the degradation of cationic neutral red undergoes a photoconversion to its neutral form during the degradation process, which in turn, lowers its degradation efficiency. On the other hand, higher degradation efficiency was observed on malachite green owing to its unique cationic form, soluble in aqueous solutions.

AfroPALM - Afrocentric palm oil adulteration learning models: An end-to-end deep learning approach for detection of palm oil adulteration

In Africa, rapid population growth and a focus on increasing food production have often overlooked the crucial aspect of food safety, leading to the highest per capita incidences of foodborne illness globally. This underscores the imperative to address the food safety challenges on the continent. A critical concern is the widespread adulteration of red palm oil across West Africa, often involving harmful red azo dyes, posing significant health risks. Current detection methods, reliant on laboratory procedures, are not only time-consuming and expensive but also impractical for broad implementation in local markets. To address these limitations, we propose an end-to-end deep learning approach that bypasses the need for manual feature extraction and laboratory-based analyses. Utilizing high-resolution imaging technology, our approach can objectively and reliably detect palm oil adulteration directly from raw image data. In our study, we developed a deep convolutional neural network dubbed AfroPALM-Custom, specifically designed for detecting palm oil adulteration in African markets. AfroPALM-Custom was pivotal in refining our deep learning approach, achieving a test accuracy of 90.63% and an F1 score of 90.98%. We later adapted mobile-efficient pretrained models, namely SqueezeNet1.1 and GhostNetV1—mobile—fine-tuned and as well dubbed AfroPALM-GhostNet and AfroPALM-SqueezeNet. In performance, AfroPALM-GhostNet and AfroPALM-SqueezeNet achieved test accuracies of 96.29% and 91.16%, respectively, and F1-scores of 96.57% and 91.95%. This proficiency in identifying adulterated palm oil demonstrates a significant advancement in food safety solutions for African markets, offering a practical and scalable approach for implementation within local marketplaces where resources are limited and laboratory methods are impractical.© 2001 Elsevier Science. All rights reserved.

Na-doped ZnO thin film by USP method for amperometric detection of Alura Red (E129) azo dye

Na-doped ZnO thin film by USP method for amperometric detection of Alura Red (E129) azo dye

Biodegradation Pathway of Congo Red azo dye by Geotrichum candidum and Toxicity Assessment of Metabolites

Biodegradation Pathway of Congo Red azo dye by Geotrichum candidum and Toxicity Assessment of Metabolites

Facile one-step synthesis and characterization of MnO nanoneedles and their application in solar photocatalysis

Manganese oxide (MnO) colloidal nanoneedles have been successfully synthesized by a facile one-step method based on the alkaline reaction of the precursor manganese acetate salt and excess sodium hydroxide. X-ray diffraction and FT-IR spectroscopy confirmed the synthesized MnO nanoneedles phase and structure. The optical properties of synthesized MnO nanoneedles were studied by UV–Vis absorption spectroscopy. Optical particle size and band gap of synthesized MnO colloidal nanoneedles were calculated. HR-TEM/SEM images and EDX allow us to determined particle shape and size. The photocatalytic activity of the MnO nanoneedles was evaluated using the Congo red azo dye in an aqueous solution under solar light irradiation. The results showed that nanoneedles, compared with commercial ZnO nanoparticles, exhibited high photocatalytic activity. The photocatalytic studies also showed that various parameters such as band gap, size, shape, and rate constant velocity remarkably affected the remotion rate of Congo red azo dye.

Solvothermal Synthesis of Cu2ZnSnSe4 Nanoparticles and Their Visible-Light-Driven Photocatalytic Activity.

Cu2ZnSnSe4 (CZTSe) nanoparticles (NPs) were successfully synthesized via a solvothermal method. Their structural, compositional, morphological, optoelectronic, and electrochemical properties have been characterized by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Field-emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), UV-vis absorption spectroscopy, and electrochemical impedance spectroscopy (EIS) techniques. Porosimetry and specific surface area in terms of the Brunauer-Emmett-Teller (BET) technique have also been studied. XRD indicates the formation of a polycrystalline kesterite CZTSe phase. Raman peaks at 173 and 190 cm-1 confirm the formation of a pure phase. TEM micrographs revealed the presence of nanoparticles with average sizes of ~90 nm. A BET surface area of 7 m2/g was determined. The CZTSe NPs showed a bandgap of 1.0 eV and a p-type semiconducting behavior. As a proof of concept, for the first time, the CZTSe NPs have been used as a visible-light-driven photocatalyst to Congo red (CR) azo dye degradation. The nanophotocatalyst material under simulated sunlight results in almost complete degradation (96%) of CR dye after 70 min, following a pseudo-second-order kinetic model (rate constant of 0.334 min-1). The prepared CZTSe was reusable and can be repeatedly used to remove CR dye from aqueous solutions.

Hydrothermal synthesis of Zingiber/ZnO for enhanced photodegradation of ofloxacin antibiotic and reactive red azo dye (RR141).

The examination of photocatalyst powders for the total removal of pollutants from aqueous solutions is a vital research subject within the realm of environmental preservation. The objective of this study is to develop a photocatalyst heterojunction consisting of Zingiber/ZnO-H for the degradation of both the reactive red dye (RR 141) and ofloxacin antibiotic in wastewater. The current investigation outlines the process of synthesising a composite material by combining Zingiber montanum extract with zinc oxide (ZnO) by a hydrothermal method. The synthesis was conducted at a temperature of 180°C for a period of 4 hours. Consequently. The photocatalyst with a constructed heterojunction shown a notable enhancement in its photocatalytic activity as a result of the improved efficiency in charge separation at the interface. The application of economically viable solar energy facilitated the complete eradication of harmful pollutants through the process of detoxification. The removal of impurities occurs by a process that follows a first-order kinetics. Among the pollutants, RR141 demonstrates the greatest rate constant at 0.02 min-1, while ofloxacin has a rate constant of 0.01 min-1. The assessment of the stability of the produced photocatalyst was conducted after undergoing five cycles. This study additionally investigated the influence of sunshine on degradation, uncovering degradation rates of 97% for RR141 and 99% for ofloxacin when exposed to UV Lamp, and degradation rates of 97% for RR141 and 95% for ofloxacin when exposed to Solar Light.

A Novel Flow Injection Method with Chemiluminescence Detection for the Determination of Carmoisine in Gelatin Desserts.

Carmoisine dye, a red azo food colorant commonly utilized to impart a red color to synthetic food products, is the subject of this study. Here, we present a novel reversed flow injection analysis with a chemiluminescence detection (FIA-CL) method employing a newly developed homemade flow cell to determine carmoisine dye. This developed method is based on the inhibition effect of the dye on the chemiluminescence light (CL) emission generated from a luminal-hypochlorite system, whereby the reduction in CL intensity correlates directly with the concentration of carmoisine dye. Investigations into various analytical parameters were conducted to enhance method efficiency and applicability. A linear calibration graph of 4.0 to 100.0µg mL-1 was established (R² = 0.9993), with a detection limit of LOD = 2.93µg mL-1. Subsequent application of the proposed method to analyze gelatine dessert samples yielded results in reasonable agreement with those obtained using the reported HPLC method, as evidenced by student t-test and F-test analyses.

Effective adsorption of fluorescent congo red azo dye from aqueous solution by green synthesized nanosphere ZnO/CuO composite using propolis as bee byproduct extract.

The indirect dumping of massive volumes of toxic dyes into water has seriously affected the ecosystem. Owing to the many applications of the designed nanomaterials in the manufacturing process, there is a lot of research interest in synthesizing nanomaterials using green processes. In this research, the byproduct of bee was employed to synthesize nanoparticles (NPs) of ZnO, CuO, and biosynthesized ZnO/CuO (BZC) nanocomposite via utilizing a green and simple approach. To validate the effective fabrication of BZC nanocomposite, various characterization measurements were applied. FTIR analysis identified the functional groups in charge of producing nanoparticles and nanocomposites. Moreover, the existence of ZnO and CuO XRD peaks suggests that the nanocomposites were successfully biosynthesized. The high-resolution XPS spectrum of the BZC nanocomposite's Zn2p3, Cu2p3, and O1s were observed. Our findings indicate the successful engineering of the prepared nanomaterials and BZC nanocomposite. Our findings indicate the successful engineering of the prepared nanomaterials and BZC nanocomposite. For Congo red (CR) fluorescent stain azo dye elimination in water, all adsorption parameters were examined at room temperature. Moreover, the adsorption experiments revealed the removal capacity for uptake CR dye using BZC nanocomposite (90.14mgg-1). Our results show that the BZC nanocomposite exhibited high removal capability for the adsorption of CR dye. The nanosphere adsorbent offered a simple, low-cost, and green approach for water purification and industrial wastewater control.

Degradation of Methyl Red Azo Dye by Hexacyanoferrate(III) Ions from Water using Ultrafine Ir–Cu Bimetallic Nanoparticles: a Kinetic Approach

Degradation of Methyl Red Azo Dye by Hexacyanoferrate(III) Ions from Water using Ultrafine Ir–Cu Bimetallic Nanoparticles: a Kinetic Approach

The Synthesis of carbon dots//zincoxide (CDs/ZnO-H400) by using hydrothermal methods for degradation of ofloxacin antibiotics and reactive red azo dye (RR141)

The development of photocatalytic powders to remove contaminants from air solutions is an important field of research in the field of environmental conservation. CD/ZnO-H400, a heterogeneous photocatalytic production, is utilized to degrade the reactive red dye and the antibiotic ofloxacin found in wastewater. This study explains the synthesis of carbon dots (CDs) derived from coconut air and zinc oxide (ZnO) using a hydrothermal method at a temperature of 180 °C with a duration of 4 h and subsequently calcinated at a 400 °C temperature for 4 h. This shows a significant improvement in photocatalytic performance due to improved delivery efficiency at the interface. The cost-efficient use of solar energy allows the comprehensive elimination of harmful pollutants through detoxification. The removal of the contaminant takes place through the first-order reaction, with RR141 showing the highest constant rate at 0.03 min−1, while ofloxacin has a constant speed at 0.01 min−1. The photocatalytic stability is measured after five cycles. The study also tested the impact of sunlight on degradation, showing a degrading rate of 98% for RR141 and 96% for ofloxacin. This study displays a new catalyst powder synthesized from carbon dots derived from the air, coconut and ZnO, showing remarkable photoactivity to completely remove harmful dyes and antibiotics from the surrounding environment.

Azo dye polyelectrolyte multilayer films reversibly re-soluble with visible light

Polymeric multilayer films were prepared using a layer-by-layer (LBL) technique on glass surfaces, by repeated and sequential dipping into dilute aqueous solutions of various combinations of water-soluble polyanions (polyacrylic acid (PAA)), polycations (polyallylamine hydrochloride (PAH) or chitosan (CS)), with bi-functional water-soluble cationic azo dyes bismark brown R bismarck brown red or bismark brown Y (BBY), or anionic azo dyes allura red (ALR) or amaranth (AMA), as ionic cross-linkers. The electrostatically-assembled ionically-paired films showed good long-term stability to dissolution, with no re-solubility in water. However, upon exposure to low power visible light under running water, the films photo-disassembled back to their water-soluble constituent components, via structural photo-isomerization of the azo ionic crosslinkers. The relative rate of the disassembly (RRD) of the films was established using UV-Vis spectroscopy, demonstrating that these assemblies can in principle represent fully recyclable, environmentally structurally degradable materials triggered by exposure to sunlight, with full recovery of starting components. A density functional theory treatment of the allura red azo dye rationalizes the geometrical isomerization mechanism of the photo-disassembly and provides insight into the energetics of the optically-induced structural changes that trigger the disassembly and recovery.

Application of grape seed and Austrocylindropuntia mucilage for the simultaneous removal of azo dye and turbidity from synthetic wastewater: Optimizing experimental conditions using Box-Behnken Design (BBD)

The purpose of this study was to explore the potential of grape seed powder (GSP) as a natural coagulant and Austrocylindropuntia mucilage (AM) as a natural flocculant to efficiently eliminate both Congo red (CR) azo dye and turbidity from synthetic wastewater using coagulation-flocculation technique. The Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) coupled with energy dispersive spectra (EDS) mapping, and X-ray photoelectron spectroscopy (XPS) techniques were used to characterize natural plants employed as well as sludge formed after coagulation-flocculation process. Moreover, response surface methodology (RSM) approach was established via Box-Behnken Design (BBD) to optimize a set of coagulation-flocculation conditions; including GSP dose, AM dose, initial pH, initial CR concentration, initial turbidity, and settling time. RSM-BBD results showed highest removal efficiency of 99.36 % and 95.74 % of CR and turbidity, respectively, achieved under optimum conditions of 0.45 mg L−1 of GSP coagulant, 6 mL L−1 of AM flocculant, at pH of 10, initial CR concentration of 5 mg L−1, initial turbidity of 250 NTU, and after settling time of 120 min. The findings of this work revealed that there are multiple mechanisms involved in CR and turbidity removal, namely hydrogen bonding, electrostatic interactions, π-π interactions, and bridging effect.

Helichrysum arenarium-mediated facile green synthesis, antibacterial, catalytic activity and hydrogen evolution of metallic (Ag, Cu) and bimetallic (Ag/Cu) nanoparticles

Metallic Ag, Cu and bimetallic Ag/Cu nanoparticles (NPs) easily and economically synthesized by green synthesis method using Helichrysum arenarium plant extracts used as reducing agent were characterized with analysis of SEM (Scanning electron microscopy), TEM (Transmission electron microscopy) and BET (Brunauer-Emmett-Teller). The adsorption study of the synthesized nanoparticles for Congo Red (CR) azo dyestuff was carried out and dyestuff removal properties were investigated in detail. At 100 min, the CR removal percentages were found to be 90.2 %, 77.8 % and 66.1 % by Cu NPs, Ag/Cu NPs and Ag NPs, respectively and the adsorption was found to be in accordance with the second order kinetic model and Langmuir isotherm model. In reusability studies of Cu NPs adsorbent, CR removal was found to be 90.2 %, 88.9 % and 83.4 % in three experimental cycles, respectively. For antimicrobial activity of Helichrysum arenarium extract, Cu NPs, Ag/Cu NPs and Ag NPs were used to against 6 pathogenic microorganisms via disc diffusion assay. As a result of the antimicrobial assay, while Helichrysum arenarium extract did not show any effect against the tested pathogenic microorganisms, both Ag NPs and Ag/Cu NPs showed an inhibition zone diameter against the tested pathogenic microorganisms (p < 0.05). It is conceivable that it would be effective in controlling the growth of resistant microorganisms in aqueous media since it produces a similar level of inhibition in methicillin-resistant and non-resistant S. aureus. Finally, the catalytic activity of the synthesized nanoparticles was evaluated in hydrogen (H2) production by hydrolysis of NaBH4. Based on experimental results, the efficiency of hydrogen production was determined as Cu NPs > Ag/Cu NPs > Ag NPs. The optimum conditions for the highest yield of H2 were investigated and the catalysis results were compared with sonocatalysis. This research shows that NPs can be synthesized in a simple, economical and environmentally friendly way and has a wide range of uses.

Decoration of silver on ZnS for enhancement of sunlight-driven photodegradation of reactive red azo dye and norfloxacin antibiotic

High charge carrier recombination rate is the major difficulty affecting low photocatalytic performance of the UV-responsive ZnS photocatalyst. To overcome the problem, well dispersion of noble metals on the ZnS surface can be regarded as one of the useful strategies to enhance the photocatalytic efficiency. This is due to a synergy of creation of heterojunction structure and surface plasmon resonance effect. In the present work, the surface of the hydrothermally grown ZnS photocatalyst was modified with 10 wt %silver. The hexagonal Ag/ZnS photocatalyst provided high sunlight-active photocatalytic performance toward removal of anionic azo dye and norfloxacin antibiotic with the efficiency of about 99 % and 70 %, within 120 min, respectively. The improvement of the resultant photoactivity is attributed to increasing of charge separation capacity at the interface. Well distribution of silver on ZnS surface results in the generation of the Schottky barrier at the Ag/ZnS interface. This will end up with the increment of quantum efficiency and enlargement of the photocatalytic activity. Additionally, after modification of ZnS surface by addition of silver, a red shift in the light absorption toward visible region was found. This is assigned to the effect of surface plasmon resonance (SPR) of Ag on ZnS surface. The synthesized Ag/ZnS reveals high structural stability with enhanced performance even after the fifth cycle. This work demonstrates a new avenue for creation of a silver-modified ZnS for complete degradation of toxic organic contaminants including dyes and antibiotics by use of the abundant solar energy.

Intermolecular interaction-controlled novel azo dyes for use in the high-performance color conversion layers of microdisplays

We synthesized four novel red azo dyes for use in a low-temperature-cured white organic light-emitting diode color conversion layer. The various substituents were introduced into the synthesized dyes to induce steric strain within the base compound for enhancing their solubility. All synthesized dyes exhibited excellent maximum absorption peaks at 521 nm, and AR4, in particular, displayed the highest molar absorptivity of 42 500. Via optimal mixing, the synthesized dyes were used to form red color resists for use in microdisplay color conversion layers. As a white backlight was applied to the optimized spin-coated films, the AR3 and AR4 films, with large dihedral angles between their substituents and diazonium planes, exhibited excellent color coordinates and transmittances, as intermolecular aggregation was inhibited. The color resists fabricated using the AR3 and AR4 dyes also displayed clear micropatterning results, confirming their high compatibility with low-temperature curing binders for use in future display production.

Facile synthesis of novel CoWO4/FeWO4 hetrocomposite with efficient visible light photocatalytic degradation and hydrogen evolution aspects

ABSTRACT Tungstate-based nanomaterials exhibit efficient photocatalytic performance and offer several advantages owing to their electrical and superior optical features, charge transport potentials, and superb corrosion resistance. The objective of the present study is to fabricate cobalt tungstate (CoWO4), Ferric tungstate (FeWO4) and CoWO4/FeWO4 heterojunction composite photocatalysts using a hydrothermal route with various molar concentrations (2:1, 1:1, 1:2, 1:5). The model pollutant Methyl Orange (MO) and Congo Red (CR) azo dyes were degraded 98.26% and 99.61% in 150 min by the as-synthesized CoWO4/FeWO4 at a molar concentration ratio of 1:2. A feasible photodegradation mechanism is purposed and the optimum values for different parameters are also evaluated by considering two different dyes as model organic pollutants. Hydrogen production efficiency reaches up to 36 μmolg−1 h−1 under visible light over 1:2 CoWO4/FeWO4. This work may open new possibilities for the use of CoWO4/FeWO4 composite for potential applications such as the hydrothermal synthesis of composites and their photocatalytic wastewater remedy and as hydrogen evolution applications.

Harnessing Efficient ROS Generation in Carbon Dots Derived from Methyl Red for Antimicrobial Photodynamic Therapy.

The emergence of drug-resistant pathogenic microorganisms has become a public health concern, with demand for strategies to suppress their proliferation in healthcare facilities. The present study investigates the physicochemical and antimicrobial properties of carbon dots (CD-MR) derived from the methyl red azo dye. The morphological and structural analyses reveal that such carbon dots present a significant fraction of graphitic nitrogen in their structures, providing a wide emission range. Based on their low cytotoxicity against mammalian cells and tunable photoluminescence, these carbon dots are applied to bioimaging in vitro living cells. The possibility of using CD-MR to generate reactive oxygen species (ROS) is also analyzed, and a high singlet oxygen quantum efficiency is verified. Moreover, the antimicrobial activity of CD-MR is analyzed against pathogenic microorganisms Staphylococcus aureus, Candida albicans, and Cryptococcus neoformans. Kirby-Bauer susceptibility tests show that carbon dots synthesized from methyl red possess antimicrobial activity upon photoexcitation at 532 nm. The growth inhibition of C. neoformans from CD-MR photosensitization is investigated. Our results show that N-doped carbon dots synthesized from methyl red efficiently generate ROS and possess a strong antimicrobial activity against healthcare-relevant pathogens.

Synthesis of porous calcium-guar gum benzoate nano-biohybrids for sorptive removal of congo red and phosphates from water

This work aims to develop an eco-sound nano-bio-hybrid sorbent using sustainable materials for sorptive elimination of congo red and phosphates from aquatic environment. An amphipathic biopolymer derivative, high DS guar gum benzoate (GGBN) was used for entrapment of as synthesized calcium carbonate nanoparticles using solvent diffusion nano-precipitation technique. Designer nano-biohybrids were developed upon experimenting with various materials stoichiometry. SEM, XRD and EDX studies confirmed near-uniform impregnation of rhombohedral calcium carbonate crystals throughout the biopolymer matrix. Average pore size distribution and surface area of final product Ca-GGBNC, were estimated from NDLFT and BET methods respectively. Analysis of adsorption findings acquired at study temperature 27 ± 2 °C showed that the maximum adsorption capacity of Ca-GGBNC recorded qmax, 333.33 mg/g for congo red azo dye and that for phosphate was at 500 mg/g. Adsorptive removal was noted and both components followed pseudo second order kinetics. Intra-particle diffusion kinetics investigation disclosed that the boundary layer effect was prominent and the adsorption rates were not solely directed by the diffusion stage. Activation energy, Ea was to be estimated using Arrhenius equation at 56.136 and 47.015 KJ/mol for congo red and phosphates respectively. The calculated thermodynamic parameters(ΔG°, ΔH°, and ΔS°) revealed the spontaneous, feasible and endothermic sorption process. Owing to active surface area, spherical size, functional moiety and porous network, antibacterial properties of nanobiohybrid were persistent and MIC against E. coli and S. aureus were recorded at 200 μg/mL and 350 μg/mL respectively.

A Novel Green Electrochemical Sensor Modified with ZnO Nanoparticles for Detection of Allura Red

Nowadays, the use of nano-sensors has been considered in order to detect various compounds. In the food industry, nano-sensors are used to detect toxins, microbes and various compounds. Allura red is a red azo dye that is used in health and cosmetic, pharmaceutical and food industries. Azo dyes have toxic effects and can cause oxidative stress response and change the expression of different genes. Therefore, it is important to detect and determine its concentration. In this study, a simple and novel electrochemical sensor modified with ZnO nanoparticles (ZnO NPs) synthesized by the green method was fabricated and used for electrochemical detection of Allura Red in food samples. Surface morphology and electrochemical properties of the prepared nanocomposite modified electrode were investigated by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Under optimized conditions, the calibration plot was linear in the concentration renege of 0.01 μM to 0.41 μM, and the limit of detection was found to be 0.001 μM. The proposed sensor was successfully applied for determination of Allura Red in food samples.