Search Results (150)

In this work, sustainable aluminum-modified orange peels functionalized with graphene oxide (OP-Al-GO) were synthesized and evaluated for the removal of Methylene Violet (MV) and Reactive Red 120 (RR120) from aqueous solutions. Adsorption performance was systematically investigated in single-dye systems, binary dye mixtures, and real textile wastewater samples, and compared with that of orange peels (OP), orange peel–aluminum composite (OP-Al), and graphene oxide (GO). pH_pzc analysis clarified the surface charge of the adsorbent, while SEM and FTIR showed that the incorporation of aluminum and GO increased roughness and functional groups appearance, enhancing dye adsorption and confirming successful interactions. The OP-Al-GO composites exhibited improved removal efficiency for both dyes (64.8% for RR120 and 96.2% for MV) at pH 3.0. The presence of aluminum improved structural stability and surface charge regulation, while graphene oxide contributed to multiple adsorption mechanisms, including electrostatic attraction and π–π interactions. The adsorption kinetics were found to follow a pseudo-second-order (PSO) kinetic model for RR120 and an intraparticle-diffusion model (IPD) for MV, while isotherm analysis revealed a Langmuir behavior for MV and a Freundlich behavior for RR120. Langmuir maximum adsorption capacities were 298.7 and 10.8 mg/g for MV and RR120, respectively. High removal efficiency was maintained in binary dye mixtures, with OP-Al-GO achieving 96.9% removal of MV and 85.7% of RR120. Furthermore, the proposed adsorbent was tested on real wastewater samples, and the results highlight that the proposed adsorbents are promising, low-cost, and environmentally sustainable for textile wastewater treatment. Full article

Synthetic azo dyes are widely used in the textile industry; however, their use often poses environmental challenges. Here, we characterized the compost bacterium Bacillus subtilis strain CKCC for the decolorization of various azo dyes, including Congo Red, Reactive Black 5, Reactive Green 19, Reactive Red 120, and Reactive Blue 4. The application of strain CKCC exhibited high decolorization efficiency by utilizing various extracellular enzymes, including azoreductase and ligninolytic enzymes such as laccase, lignin peroxidase, and manganese peroxidase, which are essential for the decolorization of azo dyes. Fourier transform infrared spectroscopy (FTIR) analysis revealed structural changes during decolorization, consistent with the degradation of key functional groups. This transformation was attributed to the cleavage of azo linkages by azoreductase, with ligninolytic enzymes functioning on phenolic and aromatic moieties. While FTIR confirmed these structural changes, our findings only provided insights at the functional-group level, and the presence or absence of specific decolorized metabolites, such as aromatic amines, requires additional analytical techniques. In this study, the phytotoxic metabolites positively affected the germination and growth of Vigna radiata, confirming that decolorization using strain CKCC significantly reduced the toxic properties of the metabolites produced during dye decolorization. Hence, our isolated strain CKCC offers a potentially effective and environmentally sustainable method for treating azo-dye effluent in the textile industry. Full article

To address the challenge of treating refractory organic dyes in textile wastewater, this study synthesized a novel copper-based composite material (designated MEL-Cu-6HNA) via a supramolecular self-assembly–pyrolysis pathway. Its core component consists of CuO/Cu₂O(SO₄), which was applied to efficiently degrade the Reactive Red 3BS dye within a sodium bicarbonate-activated hydrogen peroxide (BAP) system. This material was applied to degrade the Reactive Red 3BS dye using a sodium bicarbonate-activated hydrogen peroxide system. The morphology, crystal structure, and surface chemistry of the material were systematically characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Electron paramagnetic resonance (EPR) was employed to identify reactive species generated during the reaction. The effects of dye concentration, H₂O₂ concentration, MEL-Cu-6HNA dosage, and coexisting substances in water on degradation efficiency were systematically investigated, with active species identified via EPR. This study marks the first application of the supramolecular self-assembled CuO/Cu₂O(SO₄)₂ composite material MEL-Cu-6HNA, prepared via pyrolysis, in a sodium bicarbonate-activated hydrogen peroxide system. It achieved rapid and efficient decolorization of the recalcitrant Reactive Red 3BS dye. The three-dimensional sulfate framework and dual Cu²⁺ sites of the material significantly enhanced the degradation efficiency. MEL-Cu-6HNA achieved rapid and efficient decolorization of the recalcitrant Reactive Red 3BS in a sodium bicarbonate-activated hydrogen peroxide system. The material’s three-dimensional sulfate framework and dual Cu²⁺ sites significantly enhanced interfacial electron transfer and Cu²⁺/Cu⁺ cycling activation capacity. ·OH served as the primary reactive oxygen species (ROS), with SO₄²⁻, ¹O₂, and ·O₂⁻ contributing to sustained radical generation. This system achieved 95% decolorization within 30 min, demonstrating outstanding green treatment potential and providing a reliable theoretical basis and practical pathway for efficient, low-energy treatment of dyeing wastewater. Full article

The aim of this study was to investigate the sorption efficiency of anionic dyes—Reactive Yellow 84 (RY84) and Reactive Black 5 (RB5)—and cationic dyes—Red 46 (BR46) and Basic Violet 10 (BV10)—onto potato peels (Solanum tuberosum L.). The research scope included characterization of the sorbent material (pH_PZC, FTIR), the effect of pH on dye sorption efficiency, kinetics (pseudo-first-order and pseudo-second-order models, intraparticle diffusion model), and studies on the sorbent’s maximum sorption capacity (Langmuir 1 and 2, and Freundlich isotherms). The point of zero charge (pH_PZC) for potato peels was determined to be pH_PZC = 6.43, indicating a slightly acidic character of the material. The sorption efficiency for RB5, RY84, and BV10 was highest at pH 2, while the efficiency for BR46 was highest at pH 6. The time required to reach sorption equilibrium on the tested sorbent increased with the initial dye concentration and ranged from 180 to 270 min for RB5, RY84, and BV10, and from 45 to 210 min for BR46. The maximum sorption capacity of this material was found to be 20.85 ± 0.33 mg/g and 21.63 ± 0.34 mg/g for RB5 and RY84, respectively, and 10.28 ± 0.24 mg/g and 27.15 ± 0.87 mg/g for BV10 and BR46, respectively. Full article

In this study, the photocatalytic performance of natural clinoptilolite was enhanced through copper modification, achieved via ion exchange followed by KOH-induced precipitation, leading to materials with different copper speciation. Physicochemical characterization using WDXRF, PXRD, FTIR and N₂ physisorption revealed a transition from exchanged Cu²⁺ species at low loading to the formation of copper-bearing phases such as brochantite, Cu(OH)₂ and CuO at higher alkalinity. The Cu-modified samples were evaluated for the photocatalytic degradation of Congo red under UV irradiation. Among them, sample NZ-Cu3 exhibited the highest activity, achieving approximately 91% dye degradation within 30–40 min. Kinetic analysis demonstrated that the degradation process is better described by the pseudo-second-order model, indicating that chemisorption plays a dominant role. Radical scavenger experiments revealed that photogenerated holes (h⁺) are the primary reactive species responsible for dye degradation, while hydroxyl radicals contribute to a lesser extent. The enhanced photocatalytic performance is attributed to the synergistic effect of photocatalytic degradation, improved charge separation and the presence of surface copper species, highlighting Cu-modified clinoptilolite as a promising low-cost photocatalyst for wastewater treatment. Full article

Photodynamic therapy (PDT), which combines light and dyes, has emerged as a cost-effective, selective, and less toxic alternative to conventional chemotherapy for cutaneous leishmaniasis (CL), offering potential benefits for millions, especially those who are socioeconomically vulnerable. Therefore, this study investigated the in vitro effects of methylene blue (MB), a widely used photosensitizer with proven clinical efficacy, along with its derivatives—new methylene blue—NMB, NMB-B, and NMB-P—in PDT against L. amazonensis promastigotes, using a red LED device. Inhibitory concentrations (ICs) and 168 h proliferation curves were obtained. The production of reactive oxygen species (ROS) and the mechanism of cell death induction were analyzed by flow cytometry. PDT enhanced leishmanicidal effects compared to non-PDT conditions, reducing ICs by up to 85% and outperforming miltefosine, reaching the submicromolar range (IC_25NMB-P = 0.73 ± 0.16 µM, p < 0.05). The proliferation curve showed a consistent inhibitory effect, with MB exhibiting a greater decline than miltefosine, a pattern also observed with MB derivatives. PDT also increased ROS production by up to 5-fold and induced apoptosis-like cell death, characterized by AV⁺ parasites (up to 51.49 ± 2.90%, p < 0.0001). The results demonstrated that the tested dyes effectively eliminated L. amazonensis promastigotes, highlighting the potential of the NMB derivatives as photosensitizers and supporting further investigations. Full article

The development of cheap and efficient photocatalysts for the degradation of organic pollutants in textile printing and dyeing wastewater is of great importance for addressing environmental issues, although it remains challenging. In this study, nano-CuS particles were doped on cotton linter aerogels using a straightforward method for the degradation of methylene blue (MB) and organic pollutants in textile wastewater. Material morphology and structure were analyzed using XRD, SEM/EDS mapping, XPS, BET surface area measurements, and UV-Vis spectroscopy, while their performance was evaluated through various tests. The results demonstrated that a 10 mg catalyst material achieved complete degradation of a 20 mL methylene blue solution (15 mg/L) within 120 min. Moreover, the degradation rates of two types of textile wastewater, reactive red wastewater and reactive yellow wastewater, were both above 90% within 120 min and reached complete degradation within 150 min using the 10 mg catalyst material. The experimental results demonstrate that copper sulfide nanoparticles anchored in cotton linter carbon aerogel can increase the contact area of the photocatalytic reaction system, improve the photoelectron transfer, and thus enhance the photocatalytic reaction efficiency, providing a useful foundation for developing economical photocatalysts and effective dye degradation technologies. Full article

Textile dye effluents containing toxic organic compounds pose serious environmental challenges. In this study, novel Poly(1-vinyl imidazole)-Bis[2-(methacryloyloxy)ethyl] phosphate (PVIB) polymers were synthesized with crosslinker molar fractions ranging from 5% to 80% and were subsequently investigated as advanced adsorbents for textile dye removal. Procion Red (PR), a widely used reactive dye, was selected as the model pollutant. The materials were characterized using FTIR, TGA, DTG, SEM-EDX, WD-XRF, TEM, and BET analyses. Adsorption mechanisms were examined through kinetic, isotherm, and thermodynamic models. Among the synthesized formulations, PVIB20% achieved the best dye removal, reaching an experimental adsorption capacity of 330 mg g⁻¹ within 60 min under acidic to neutral conditions. The kinetic modeling studies identified the pseudo-first-order model as the best fit, indicating a surface-controlled process involving both physical and chemical interactions. Isotherm studies showed that the Langmuir and Redlich–Peterson models provided the best fit, yielding a maximum monolayer adsorption capacity of 765 mg g⁻¹. Thermodynamic analysis revealed that the adsorption was spontaneous, endothermic, and entropy-driven. Overall, PVIB20% demonstrated superior adsorption capacity, rapid kinetics, and strong dye–polymer interactions compared with many conventional and modified adsorbents, which highlights its potential as an efficient and durable material for anionic dye removal from wastewater. Full article

In systemic diseases, controlling oral bacteria and cancer is an important issue. As biomaterials, recently, carbon dots (DSs) are the focus of a variety of studies owing to their extensive applicability in life sciences. In this study, the effectiveness of carbon dots (CDs) for the elimination of both oral bacteria and oral cancer in vitro was assessed using a dental light-curing unit (LCU) as a light source. CDs were synthesized using an amino acid. The absorbance of CDs and the emission spectrum of the LCU were measured. The production of reactive oxygen species (ROS) was evaluated spectroscopically. Changes in glutathione (GSH) content were evaluated. Using oral bacteria and cancer cells, in vitro antibacterial and antitumor capabilities of CDs were evaluated under light irradiation. Confocal microscopy was used to observe live/dead cells and intracellular lipid peroxidation (LPO). The emission spectrum of the LCU fully matched the absorbance of CDs. After CD treatment, the initial peak absorbances of the p-nitrosodimethylaniline-imidazole (for singlet oxygen assay) and nitroblue tetrazolium (for superoxide oxide assay) solutions changed under light irradiation. The initial peak absorbance of the GSH assay solution decreased during and after light irradiation. Both CD-treated oral bacteria and oral cancer cells were near totally eliminated at 50 and 200 μg/mL concentrations, respectively, after light irradiation. In the live/dead cell and C11-BODIPY^581/591 dye assays, red and green fluorescent spots were, respectively, observed in the CD-treated and light-irradiated cells. Accordingly, CDs effectively eliminated both oral bacteria and cancer cells in vitro in conjunction with dental LCU with less damage to normal cells through ROS-induced or ROS-initiated GSH depletion-induced intracellular LPO. Dental LCU plays a crucial role in ROS production through CD photoexcitation. Dental LUC has the potential to be used as a light source in dentistry for the treatment of oral bacteria and cancer cells. Full article

This study transformed discarded courgette biomass into biochar (BC) via pyrolysis at 500 °C and employed it as an activator of potassium periodate (PI) for atrazine (ATZ) degradation. Characterization analyses confirmed that the synthesized BC possessed a porous structure, a high carbon content (76.13%), crystalline SiO₂, KCl, and CaCO₃ phases, as well as abundant oxygen-containing functional groups (–OH, C=O, C=C, –COOH), which are favorable for catalytic activation. The point of zero charge of 4.25 indicates that the BC surface carries a suitable charge distribution, promoting effective electrostatic interactions under near-neutral pH conditions. Under optimal operating conditions (neutral pH, [ATZ]_o = 7.3 mg/L, [PI]_o = 2.7 mM, [BC]_o = 0.55 g/L, and 25 ± 0.5 °C), the system achieved 99.35% ATZ removal (first-order kinetic rate constant = 0.0601 min⁻¹) and 64.23% TOC mineralization within 60 min. Quenching tests confirmed iodate radicals and singlet oxygen as the primary species, with hydroxyl and superoxide radicals playing secondary roles. The proposed mechanism suggests that electron transfer from oxygen-containing groups on the BC surface activates PI, leading to the generation of reactive oxygen species that facilitate ATZ degradation via synergistic radical and non-radical pathways. The BC catalyst exhibited strong recyclability, with only ~9% efficiency loss after five cycles. The BC/PI system also demonstrated high removal of tetracycline (79.54%) and bisphenol A (85.6%) within 60 min and complete Congo red dye degradation in just 30 min. Application to real industrial wastewater achieved 72.77% ATZ removal, 53.02% mineralization, and a treatment cost of 1.2173 $/m³, demonstrating the practicality and scalability of the BC/PI system for sustainable advanced wastewater treatment. Full article

In the aspect of water purification, a photoactive hybrid material based on reduced graphite oxide (RGO) with covalently, coordinatively, and through van der Waals interactions bonded zirconium(IV) phthalocyanine (PcZr) is proposed. In the material, the phthalocyanine complex plays the role of photosensitizer, while RGO is considered a carrier, ensuring high surface area and supporting PcZr activation. The central metal atom of PcZr directly interacts with lateral active oxygen-containing surface groups of graphite oxide, mainly –OH and –COOH. Thus, the proposed method of synthesis under solvothermal conditions allowed obtaining a relatively high concentration of the dye (0.2 wt.%) in the system based on a partially reduced and exfoliated graphite oxide. Optical studies confirmed the presence of PcZr through absorption and luminescence spectra. Additionally, effective generation of reactive oxygen species was demonstrated by testing the transformation of a dye indicator (diphenylisobenzofuran). Photocatalytic activity of the system was confirmed by photooxidizing selected organic dyes (methylene blue, Rhodamine B, Brilliant Green, and Eriochrome Black T) in a water medium, tested in slightly acidic conditions under red light. The greatest overall decrease in absorption during the photodegradation test was observed for Brilliant Green, reaching 88% after 3 h of irradiation. Full article

The photoinitiation properties of two porphyrins were evaluated for the free-radical photopolymerization (FRP) of a bio-based acrylated monomer, i.e., soybean oil acrylate (SOA). Their combination with various co-initiators, such as a tertiary amine as electron donor (MDEA), an iodonium salt as electron acceptor (Iod), as well as two biosourced co-initiators used as H-donors (cysteamine and N-acetylcysteine), makes them highly efficient photoinitiating systems for FRP under visible light irradiation. Electron paramagnetic resonance spin trapping (EPR ST) demonstrated the formation of highly reactive radical species, and fluorescence and laser flash photolysis highlighted the chemical pathways followed by the porphyrin-based systems under light irradiation. High acrylate conversions up to 96% were obtained with these different systems at different irradiation wavelengths (LEDs@385 nm, 405 nm, 455 nm, and 530 nm), in laminate or under air. The final crosslinked and bio-based porphyrin-based materials were used for the full photo-oxidation in water of an azo-dye (acid red 14) and under UV irradiation. These materials have been involved in three successive depollution cycles without any reduction in their efficiency. Full article

This research presents the study of utilizing the cocoa husk biomass waste to obtain active carbon through carbonization method, followed by chemical–thermal activation. The activated carbon (CH) was characterized using BET, SEM–EDX, XPS, and Raman techniques. The obtained material showed a high specific surface area of 1661 m²·g⁻¹, and XPS confirmed the presence of oxygen-containing surface functionalities. The adsorption of reactive dye Drimaren Red K-7B by CH was studied to assess the impact of the initial concentration in water solution, temperature, and contact time. The adsorbent achieved over 90% removal within three minutes at 40 °C. The experimental data for the adsorption of Drimaren Red K-7B using CH showed a good fit with the Dubinin–Radushkevich isotherm and a pseudo-second-order kinetic model. This research offers a promising approach for advancing the circular economy through the obtaining of eco-friendly adsorbents derived from biomass waste, exhibiting high initial adsorption efficiency and rapid uptake kinetics towards reactive dye. Full article

Photodynamic inactivation and antimicrobial photodynamic therapy (PDI/APDT) based on the toxic properties of reactive oxygen species (ROS), which are generated by a number of photoexcited dyes, are promising for preventing and treating infections, especially those associated with drug-resistant pathogens. The negatively charged bacterial cell surface attracts polycationic photosensitizers, which contribute to the vulnerability of the bacterial plasma membrane to ROS. The integrity of the plasma membrane is critical for the viability of the bacterial cell. Polycationic phthalocyanines are regarded as promising photosensitizers due to their high quantum yields of ROS generation (mainly singlet oxygen), high extinction coefficients in the far-red spectral range, and low dark toxicity. For application in PDI/APDT, the wide range of possibilities of modifying the chemical structure of phthalocyanines is particularly valuable, especially by introducing various peripheral and non-peripheral substituents into the benzene rings. Depending on the type and location of such substituents, it is possible to obtain photosensitizers with different photophysical properties, photochemical activity, solubility in an aqueous medium, biocompatibility, and tropism for certain structures of photoinactivation targets. In this study, we tested novel water-soluble Zn (II) phthalocyanines bearing four 4-((diethylmethylammonium)methyl)phenoxy substituents with symmetric and asymmetric charge distributions for photodynamic antibacterial activity and compared them with those of water-soluble octacationic zinc octakis(cholinyl)phthalocyanine. The obtained results allow us to conclude that the studied tetracationic aryloxy-substituted Zn(II) phthalocyanines effectively bind to the oppositely charged cell wall of the Gram-negative bacteria E. coli. This finding is supported by data on bacteria’s zeta potential neutralization in the presence of phthalocyanine derivatives and fluorescence microscopy images of stained bacterial cells. Asymmetric substitution influences the aggregation and fluorescent characteristics but has little effect on the ability of the studied tetracationic phthalocyanines to sensitize the bioluminescent E. coli K12 TG1 strain. Both symmetric and asymmetric aryloxy-substituted phthalocyanines are no less effective in PDI than the water-soluble zinc octakis(cholinyl)phthalocyanine, a photosensitizer with proven antibacterial activity, and have significant potential for further studies as antibacterial photosensitizers. Full article