Background: In recent years, azo dyes have become the dominant choice in the textile industry, accounting for about 60-70% of all dyes used, which has led to growing environmental concerns. Aim: This research focused on the photocatalytic degradation of methyl orange (MO) and methyl green (MG) dyes using a novel g-C₃N₄ (GCN)/polyaniline (PANI)/Ag composite under visible light. Methods: This composite was synthesized through a straightforward preparation process and characterized by using various techniques, including UV-visible spectroscopy (UV-Vis), Fourier- transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and cyclic voltammetry (CV). Results: Characterization results confirmed the incorporation of PANI and Ag nanoparticles into the GCN matrix. This composite enhanced the visible light absorption and improved charge separation, leading to increased photocatalytic efficiency. Photocatalytic experiments were conducted under visible light irradiation with a catalyst dosage of 10 mg in a 10-ppm solution of the MO and MG dyes mixture. Conclusion: The GCN/PANI/Ag composite achieved significant degradation efficiencies of 70% for MO and 69% for MG within 120 minutes. The degradation process followed first-order kinetics, with rate constants of 0.0087 min⁻¹ for MO and 0.0086 min⁻¹ for MG, respectively. Reusability tests showed that the composite retained over 60% of its initial efficiency after five cycles. These findings highlight the potential of the GCN/PANI/Ag composite as a sustainable and effective photocatalyst for visible-light-driven dye degradation, offering an eco-friendly approach to wastewater treatment.

Piezoelectric-driven self-powered sensor with tunable plasmonic hotspots for enhanced SERS performance.

Removal of methyl orange from wastewater using sustainable and facilely synthesized weathered basalt/chitosan/polyaniline composites.

Disaccharide/UiO-66(Zr) composites for selective dye adsorption: synergistic mechanisms.

Valorization of banana peel waste into Zr-MOF@AC composite for sustainable methyl orange removal from water with kinetic, isothermal and thermodynamic insights

Dual-modified tobermorite with carbon and magnesium oxide for adsorbing methyl orange and methylene blue

Phytoremediation of Congo red and methyl orange dye-contaminated water with the coontail Ceratophyllum demersum aquatic plant

Exploring nickel-modified sodalite zeolite for efficient methyl orange removal from aqueous solutions: A comprehensive mechanistic and equilibrium analysis

Synergy effect of sulfite, visible light, and catalyst in highly efficient photocatalytic degradation of methyl orange with sulfite activation by ZnxMg3-xAl-LDH/g-C3N4 composite: Performances, roles, and mechanism

Catalytic wet peroxide of oxidation of methyl orange with in-situ generated H2O2 over Pd/ZIF-67(FeCo) catalysts

The present study involves the synthesis of polyvinylpyrrolidone (PVP)-stabilized iron-based trimetallic nanoparticles with different metal addition sequences (Fe/Ag/Zn, Fe/Zn/Ag and Fe/(Zn/Ag)) using the sodium borohydride reduction method. In order to investigate the catalytic reactivity of the nanoparticles, a series of batch experiments were performed using methyl orange dye as a model pollutant. It was found that the Fe/Ag/Zn system showed the maximum catalytic activity compared to the other studied trimetallic systems. About 100% of the methyl orange dye was removed within 1 min and the second-order rate constant obtained was 0.0744 (mg/L)−1 min−1; the rate of reaction was higher than that of the other trimetallic systems. Furthermore, the effects of pH, initial dye concentration and nanoparticle dosage on the degradation of methyl orange were investigated. The results showed that the reactivity of the Fe/Ag/Zn trimetallic nanoparticles was highly dependent on the aforementioned parameters. Higher reactivity was obtained at lower pH, lower initial methyl orange dye concentration and higher nanoparticle dosage. Lastly, liquid chromatography–mass spectroscopy (LC-MS) was used to elucidate the reaction pathway and identify by-products from methyl orange degradation. The developed catalyst demonstrated exceptionally rapid and apparent degradation of methyl orange within one minute, outperforming previously reported bimetallic and trimetallic systems. This work reports a cost-effective nZVI-based trimetallic system containing minimal silver, which shows promising reactivity toward azo dye degradation and may be suitable for future application in textile wastewater treatment.

A cobalt-containing zeolitic imidazolate framework (ZIF-67) was carbonized by different routes to composite materials (cZIFs) composed of metallic Co, Co3O4, and N-doped carbonaceous phase. The effect of the carbonization procedure on the water pollutant removal properties of cZIFs was studied. Higher temperature and prolonged thermal treatment resulted in more uniform particle size distribution (as determined by nanoparticle tracking analysis, NTA) and surface charge lowering (as determined by zeta potential measurements). Surface-governed environmental applications of prepared cZIFs were tested using physical (adsorption) and electrochemical methods for dye degradation. Targeted dyes were methylene blue (MB) and methyl orange (MO), chosen as model compounds to establish the specificity of selected remediation procedures. Electrodegradation was initiated via an intermediate reactive oxygen species formed during oxygen reduction reaction (ORR) on cZIFs serving as electrocatalysts. The adsorption test showed relatively uniform adsorption sites at the surface of cZIFs, reaching a removal of over 70 mg/g for both dyes while governed by pseudo-first-order kinetics favored by higher mesoporosity. In the electro-assisted degradation process, cZIF samples demonstrated impressive efficiency, achieving almost complete degradation of MB and MO within 4.5 h. Detailed analysis of energy consumption in the degradation process enabled the calculation of the current conversion efficiency index and the amount of charge associated with O2•−/•OH generation, normalized by the quantity of removed dye, for tested materials. Here, the proposed method will assist similar research studies on the removal of organic water pollutants to discriminate among electrode materials and procedures based on energy efficiency.

The main emphasis of the current study is to develop an eco-friendly method for producing silver nanoparticles (AgNPs) using an aqueous flower extract from Talipariti tiliaceum L., and to evaluate the photocatalytic degradation of azo dyes. The synthesized AgNPs were characterized using various spectroscopical and microscopical methods. The photocatalytic capacity of AgNPs was assessed through the degradation of methylene blue (MB) and methyl orange (MO) dye under solar irradiation. The results revealed that the AgNPs were spherical in morphology and 4–15 nm in size. The phytochemical analysis showed that the bioactive compounds from the flower extract aided in the reduction of silver ions to nanoparticles. Both visual observations and spectroscopic methods confirmed the photocatalytic degradation of MB and MO dyes. The degradation processes adhered to a pseudo-first-order kinetic model, demonstrating that photocatalytic activity is time-dependent. In addition, the AgNPs demonstrated stability and reusability through four consecutive cycles with little decline in efficiency. This research contributes significantly to sustainable nanotechnology, offering a practical solution for mitigating water pollution caused by industrial dye discharges.

In this study, the calcination temperature of TiO2 nanoparticles was investigated at 300, 350, 400, and 450 °C. The results indicated that 400 °C was the optimal calcination temperature, yielding the highest amount of synthesized TiO2 nanoparticles remaining in the anatase phase (97.44 %). TiO2 nanoparticles were coated on cordierite using two methods: spray coating and dip coating. Their characteristics were analyzed and evaluated utilizing several modern techniques. Additionally, their photocatalytic and recovery capabilities were assessed based on methylene orange (MO) degradation efficiency. The spray coating method allowed the TiO2 nanoparticles to evenly cover the cordierite surface, resulting in the highest MO degradation efficiency and best recovery ability. The MO degradation efficiency remained at 83.07 % after 5 reuse cycles. Copyright © 2025 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Three-dimensional ZnO structures were prepared by both thermal atomic layer deposition (ThALD) and plasma-enhanced atomic layer deposition (PEALD) on a sacrificial cellulose template. The synthetic approach consisted of ALD of conformal ZnO nanofilms on the fibrous cellulose template, followed by thermal removal of the polymer. The resulting calcinated samples, consisting of a scaffold of fused polycrystalline ZnO nanoparticles, showed a sevenfold and ninefold increase in photocatalytic activity against methyl orange under ultraviolet-A light, for the ThALD and PEALD samples, respectively, compared to the non-calcined samples prior to cellulose removal. In addition to the improved three-dimensional surface exposure and accessible active sites, it was suggested that the amount of hydroxyl groups on the surface and the density of nanoparticle packing in 3D ZnO structures are critical parameters for improving the photoinduced degradation of the dye.

ABSTRACT Spontaneous gelation, which involves in situ polymerization followed by network crosslinking of monomers under ambient or moderately elevated temperatures, occurring without the incorporation of external initiators or catalysts, is a major challenge in polymer chemistry and environmental science. In this work, we report the design and synthesis of amino acid‐derived porous hydrogels prepared via a spontaneous gelation without any external trigger, utilizing a glutamic acid‐derived monomer N‐methacryloyl‐(L)‐glutamic acid (MAGA) without the need for any additional crosslinking agents. Copolymers of MAGA with DMAEMA or DMA are synthesized through free‐radical polymerization and used to initiate gelation with acrylamide via persulfate activation, enabled by the N,N‐dimethyl functionalities in the copolymers. The resulting poly(DMAEMA‐ r ‐MAGA)/PAAm and poly(DMA‐ r ‐MAGA)/PAAm composite hydrogels demonstrated rapid gelation at ambient temperature, significant structural integrity, and tunable porous structures, as confirmed by rheological studies and electron microscopic imaging. These hydrogels exhibited excellent dye adsorption efficiency toward both anionic (Eosin B, Methyl Orange) and cationic (Rhodamine B) organic dyes. The system's ability to form defined shapes via mould printing, along with its bio‐derived fabrication, scalability, and performance, presents a promising route for future use in 3D‐printed devices and sustainable wastewater treatment. This catalyst‐free, crosslinker‐free, and ambient‐condition gelation approach marks a significant step toward environmental friendly hydrogel technologies.

Abstract A facile one-step synthesis of β-cyclodextrin-substituted alginate (Alg-β-CD) was achieved through a condensation reaction between sodium alginate (AlgNa) and 6-amino-6-deoxy-β-cyclodextrin (NH₂-β-CD) in H2O. NMR and IR analyses confirmed the covalent incorporation of β-CD units. The hydrogel beads prepared from Alg-β-CD exhibited enhanced inclusion of methyl orange (MO) compared with those from AlgNa, showing higher initial uptake and 38% retention after 360 min. Pseudo-second-order kinetic analysis revealed slower MO release from Alg-β-CD, demonstrating a simple and sustainable route to functional Alg-based materials with guest-recognition capability.

The fabrication of undoped and aluminium-doped zinc oxide thin films on quartz glass substrates through the aqueous spray method is reported. The prepared aqueous precursor solutions containing Zn2+ and varying mole percentages (0, 2, 4, and 8%) of Al3+ complexes were spray-coated onto quartz glass substrates preheated at 180 °C. The as-sprayed films obtained were then heat-treated at 450 °C for 30 min in a furnace to produce the various thin films. The structural and optical properties of the resultant thin films were analysed using the X-ray diffractometer (XRD) and ultraviolet–visible (UV-Vis) spectrophotometer. The XRD results revealed that the fabricated thin films have a prominent peak correlating to the (002) Miller index, which is the preferred orientation of the zinc oxide hexagonal wurtzite phase. The fabricated thin films with a film thickness of approximately 189 nm absorb light in the visible region and have a transmittance of over 80% even after being doped with aluminium. The photocatalytic activities of the thin films were evaluated via visible light irradiation of an aqueous methyl orange solution, and the Al-doped ZnO thin films exhibited good photocatalytic activities, which resulted in an increase in the doping mole percentages of aluminium.

Electrochemical performance of MnO2-TiO2 nanocomposite for methyl orange sensing applications

Microbial biofilm-based hydrovoltaic system for degradating organic pollutants.