Search Results (152)

The green-chemical preparation of silver nanoparticles (AgNPs) offers a sustainable and environmentally friendly alternative to conventional synthesis methods, thereby representing a paradigm shift in the field of nanotechnology. The biological synthesis process, which involves the synthesis, characterization, and management of materials, as well as their further development at the nanoscale, is the most economical, environmentally friendly, and rapid synthesis process compared to physical and chemical processes. Ligustrum ovalifolium flower extract was used for the preparation of AgNPs. The synthesized AgNPs were examined by using UV–visible spectroscopy, XRD, SEM, and TEM analysis. It indicates that AgNPs were formed in good size. AgNPs were applied as a catalyst for the degradation of pollutants, such as methyl orange, Congo red, and methylene blue, which were degraded within 8–16 min. Additionally, the reduction of para-nitrophenol (PNP) to para-aminophenol (PAP) was achieved within 2 min. This work demonstrates a practical, reproducible, and efficient method for synthesizing cost-effective and stable AgNPs, which serve as active catalysts for the rapid degradation of hazardous organic dyes in an aqueous environment. Full article

To successfully prepare cellulose hydrogels through a dissolution–regeneration process, 60 wt% LiBr aqueous solution was used as a green solvent. Carboxyl groups were precisely introduced onto the surface of the cellulose hydrogels through a TEMPO-mediated oxidation reaction, while the three-dimensional network structure and open pore morphology were completely retained. This modification strategy significantly enhanced the loading capacity of the hydrogels with copper nanoparticles (Cu NPs). The experimental results show that the LiBr aqueous solution can efficiently dissolve cellulose, and the TEMPO oxidation introduces carboxyl groups without destroying the stability of the hydrogels. Cu NPs are uniformly dispersed and highly loaded on the surface of the hydrogel because of the anchoring effect of the carboxyl groups. Cu NP-loaded hydrogels exhibit excellent catalytic activity in the NaBH₄ reduction of 4-nitrophenol (4-NP). Cu NP-loaded hydrogels maintain their complete structure and good catalytic performance after five consecutive cycles. Moreover, Cu NP-loaded hydrogels demonstrate high efficiency in degrading organic dyes such as methyl orange and Congo red. This study successfully developed efficient, low-cost, and environmentally friendly Cu NP-loaded hydrogel catalysts through the synergistic effect of LiBr green solvent and TEMPO oxidation modification, providing a feasible alternative to noble metal catalysts. Full article

This study investigates the catalytic potential of silver nanoparticles (AgNPs) synthesized using aqueous Cymbopogon citratus (lemongrass) extract for the degradation of toxic textile dyes, offering an eco-friendly solution to industrial wastewater treatment. The green-synthesized AgNPs demonstrated remarkable degradation efficiency (>94%) for multiple dyes, such as rhodamine B, methyl red, methyl orange, methylene blue, eosin yellow, and Eriochrome black T, in the presence of sodium borohydride. Optimization studies employing a one-factor-at-a-time approach revealed the critical influence of AgNPs and reductant concentration, temperature, and pH. Kinetic analysis confirmed pseudo-first-order degradation behavior. Reactive species scavenging experiments established that hydroxyl radicals and holes played dominant roles in the degradation mechanism. Notably, the AgNPs retained catalytic activity across eight reuse cycles with negligible performance loss, demonstrating strong potential for repeated application. Comparative analysis with data from the literature highlights the superior performance of C. citratus-derived AgNPs in terms of reaction rate and efficiency. This work underscores the value of plant-extract-mediated AgNPs synthesis not only for its environmental compatibility but also for its catalytic effectiveness. The study advances the practical applicability of green nanotechnology in wastewater remediation and supports its integration into sustainable industrial practices. Full article

Precise separation and antifouling capabilities are critical for the application of membrane separation technology. In this work, we developed a multiplayer layer-by-layer assembly strategy to sequentially deposit tannic acid (TA) and lysozyme (Lys) onto polyethersulfone/iron (PES/Fe) ultrafiltration membrane substrates, enabling the simple and efficient fabrication of a biofouling-resistant loose nanofiltration (LNF) membrane with superior dye/salt separation performance. This approach fully leverages the multifunctionality of TA by exploiting its coordination with Fe³⁺ and non-covalent interactions with Lys. The obtained PES/Fe-TA-Lys LNF membrane exhibits a pure water flux of 57.5 L·m⁻²·h⁻¹, along with exceptional dye rejection rates (98.3% for Congo Red (CR), 99.2% for Methyl Blue (MB), 98.4% for Eriochrome Black T (EBT), and 67.6% for Acid Orange 74 (AO74)) while maintaining minimal salt retention (8.2% for Na₂SO₄, 4.3% for MgSO₄, 3.5% for NaCl, and 2.4% for MgCl₂). The PES/Fe-TA-Lys LNF membrane also displays outstanding antifouling performance against bovine serum albumin (BSA), humic acid (HA), and CR, along with strong biofouling resistance against Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) via synergistic anti-adhesion and biofilm inhibiting effects. This work presents a novel and scalable approach to fabricating biofouling-resistant LNF membranes, offering great potential for dye/salt separation in textile wastewater treatment. Full article

Smart packaging materials (SPMs) combine the properties of intelligent and active packaging into a single system, enabling for the monitoring of the packaged product while enhancing its desired conditions. In this study, poly(lactic acid) (PLA) was used as the base polymer and functionalized with in situ synthesized gold nanoparticles (AuNPs) and methyl red (MR) as a pH-sensitive dye. Various additives, including poly(amic) acid (PAA), bromothymol blue (BB), 5-aminosalicylic acid (5AS), glutaraldehyde (GA), and silver and gold nanoparticles (AgNPs, Au NPs), were tested to optimize the SPMs. To evaluate their performance, the synthesized SPMs were characterized using UV-Vis spectroscopy, IR spectroscopy, SEM, microbiological assays, and mechanical tests. Our results revealed that PLA films containing AuNPs and MR exhibited excellent mechanical, chemical, and antimicrobial properties, making them highly suitable for smart packaging applications. In contrast, the addition of PAA disrupted film formation, while AgNPs and blueberry extracts increased the brittleness of the films, thereby limiting their practical use. Furthermore, BB was found to inhibit the in situ synthesis of AuNPs. A real-world application study demonstrated that cheddar cheese wrapped in the optimized PLA films remained unspoiled after 12 months of refrigeration. IR spectroscopy confirmed that no film components migrated into the cheese during the storage period. GA was identified as a critical component for maintaining the structural integrity of the films over the 12-month storage period. This is the first study to report on the development of PLA-based SPMs that incorporate AuNPs, MR, and GA, offering a promising solution for sustainable and intelligent food packaging. Full article

Nanotechnology offers effective solutions for removing contaminants and harmful bacteria from polluted water. This study synthesized copper nanoparticles using a carbohydrate-based bioflocculant derived from Proteus mirabilis AB 932526.1. The bioflocculant is a natural polymer that facilitates the aggregation of particles, enhancing the efficiency of the nanoparticle synthesis process. Characterization of the bioflocculant and copper nanoparticles was conducted using Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, Energy-Dispersive X-ray Spectroscopy, Ultraviolet-Visible Spectroscopy, X-ray Diffraction, and Transmission Electron Microscopy techniques to assess their properties, flocculation efficiency, and antibacterial characteristics. The optimal flocculation efficiency of 80% was achieved at a copper nanoparticle concentration of 0.4 mg/mL, while a concentration of 1 mg/mL resulted in a lower efficiency of 60%. The effects of biosynthesized copper nanoparticles on human-derived embryonic renal cell cultures were also investigated, demonstrating that they are safe at lower concentrations. The copper nanoparticles effectively removed staining dyes such as safranin (90%), carbol fuchsine (88%), methylene blue (91%), methyl orange (93%), and Congo red (94%), compared to a blank showing only 39% removal. Furthermore, when compared to both chemical flocculants and bioflocculants, the biosynthesized copper nanoparticles exhibited significant nutrient removal efficiencies for nitrogen, sulfur, phosphate, and total nitrates in coal mine and Vulindlela domestic wastewater. Notably, these biosynthesized copper nanoparticles demonstrated exceptional antibacterial activity against both Gram-positive and Gram-negative bacteria. Full article

Water pollution is a critical environmental issue in modern society, and adsorption is recognized as a straightforward and efficient water purification technique. In this study, three new viologen-based ionic porous organic polymers were designed and successfully synthesized via a simple approach, and their adsorption properties for water pollutants were evaluated. The cationic nature of these polymers, coupled with their large conjugated π-electron system, physicochemical stability, and aromatic backbone, contributes to their high adsorption capacity and rapid adsorption efficiency for anionic contaminants in water such as Methyl Orange, Congo Red, and Cr (VI). The polymers exhibited maximum adsorption capacities of 1617 mg/g for MO, 3734 mg/g for CR, and 530.22 mg/g for Cr (VI), surpassing most previously reported adsorbents. Furthermore, the polymers maintained a high removal rate even in the presence of competing anions. Effective separation of anionic dyes from mixed solutions could be achieved through simple filtration. These characteristics make them promising candidates for water purification applications. Full article

The increasing generation of agro-industrial waste has intensified soil and water contamination, as well as the eutrophication of water bodies, impacting biodiversity and human health. This highlights the need for responsible management to meet Sustainable Development Goals (SDGs) 3, 6, 12, 13, 14, and 15, which promote health, access to clean water, responsible consumption, climate action, and the protection of life on land and below water. This study aimed to produce activated carbon from cocoa, baru, and monguba residues for the removal of contaminants dyes (methylene blue, bromocresol green, and methyl red) presented in wastewater. The three materials were carbonized at 500 °C for one hour under a nitrogen atmosphere and activated with H₃PO₄. The samples were characterized using TGA, SEM, XRD, FT-IR, pH_PZC, and ASAP, in addition to conducting kinetic and thermodynamic parameter assays for the dyes. Monguba carbon exhibited the highest pore volume (1.57 cm³·g⁻¹), surface area (1604 m²·g⁻¹), and adsorption capacity for methylene blue and methyl red (50 mg·g⁻¹). The data were analyzed using pseudo-first and pseudo-second order kinetic models. It was concluded that monguba carbon shows potential for the sustainable removal of organic dyes and molecules with similar characteristics in contaminated water or wastewater. Full article

Removing high-concentration organic dye from wastewater is of great concern because the hazards can cause serious damage to the environment and human health. In this study, the hybrid dimensionally stable anode (DSA) with a Ce-doped and SnO₂-Sb₂O₅ intermediate layer was fabricated and used for the electro-catalytic oxidation of three kinds of ultra-high-concentration organic dyes. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) confirmed the denser surface structure and morphology of the composite Ti/SnO₂-Sb₂O₅/Ce-PbO₂ electrode. Moreover, the electrode exhibited an excellent oxygen evolution potential of 1.58 V. The effect on the removal efficiencies of high concentrations of up to 1 g/L of methyl orange, methylene blue, and neutral red solutions with the above composite electrode was investigated. The research results illustrated that target molecules in the three different dye solutions were rapidly decolorized and decomposed by electro-catalytic oxidation in less than 35 min. Additionally, the degradation process still followed pseudo-first-order kinetics for high-concentration dye solutions. The removal efficiency of Total Organic Carbon (TOC) and Chemical Oxygen Demand (COD) for the three dye solutions was more than 98%, and the results of the gas chromatography–mass spectrometry (GC-MS) analysis showed that it had the best degradation effects for neutral red, which decomposed more thoroughly. More than 80 h of accelerated life also revealed excellent performance of the composite electrode in the face of high-concentration dye solution degradation. Considering these results, the Ti/SnO₂-Sb₂O₅/Ce-PbO₂ anode could be utilized to treat wastewater containing high-concentration dyes with high efficiency. Full article

Based on the magnetic sensitivity of Fe₃O₄ in various fields, we aimed to propose a one-step solvothermal process for the synthesis of single-phase Fe₃O₄ induced by the reaction medium and urea, avoiding high-temperature reduction in H₂ or N₂ atmospheres. Feasibility was tested with purified water (H₂O), methyl alcohol (MA), ethyl alcohol (EA), and ethylene glycol (EG) as reaction media. The findings indicated that the solvothermal reaction system utilizing EA was more effective for the synthesis of cubic magnetic Fe₃O₄. Optimal conditions for synthesizing pure Fe₃O₄ were obtained by optimizing the urea amount and solvothermal reaction parameters. The optimal formulation consisted of 10 mmol of FeCl₃, 80 mmol of urea, and 60 mL of EA subjected to a solvothermal process at 200 °C for 12 h. The resulting Fe₃O₄ (magnetite, cubic) exhibited commendable crystallization with a morphology of acicular aggregates and displayed excellent magnetic sensitivity properties with a magnetization of 92.2 emu/g at 15,000 Oe. The photocatalytic degradation behaviors of the resulting Fe₃O₄ to Methyl Orange, Orange G, and Acid Red 37 azo dyes and the repeated degradation performance of Methyl Orange dye were investigated. Nearly complete degradation of Methyl Orange dye occurred after 2.0 h of photocatalytic reaction, while Orange G and Acid Red 37 dyes achieved similar results after 3.5 and 4.5 h, respectively. The exploration strategy in this work for synthesizing magnetic Fe₃O₄ can be applied to design and fabricate other metal oxides or composites, potentially resulting in novel discoveries in morphology or performance. Full article

Binary solvent mixtures of the non-ionic surfactant Triton X-100 with water, methanol, ethanol, and 1-propanol, respectively, were investigated by solvatochromic studies. The absorption spectral bands of methyl red dye, used as a solvatochromic probe, were recorded in ternary solutions prepared with different mole ratios between Triton X-100 and water/alcohols. The Kamlet–Abboud–Taft model was applied to estimate the contribution of each type of intermolecular interaction to the total shift of the electronic absorption band of the solute. The composition of the solute molecule’s first solvation shell was comparatively estimated by using three models: the statistical cell model of ternary solutions, the Suppan model, and the Bosch–Rosés model. The statistical cell model allows the estimation of the difference between the interaction energies in the solute–solvent pairs of molecules. The Bosch–Rosés model provided important information on the 1:1 complex formed between Triton X-100 and water/alcohol molecules, as well as on the symmetry/asymmetry related to the binary mixtures in the cybotactic region of the solute’s molecule. Full article

This work aims to determine the mechanism of the photomechanical response of poly(Methyl methacrylate) polymer doped with the photo-isomerizable dye Disperse Red 1 using the non-isomerizable dye Disperse Orange 11 as a control to isolate photoisomerization. Samples are free-standing thin films with thickness that is small compared with the optical skin depth to assure uniform illumination and photomechanical response throughout their volume, which differentiates these studies from most others. Polarization-dependent measurements of the photomechanical stress response are used to deconvolute the contributions of angular hole burning, molecular reorientation and photothermal heating. While photo-isomerization of dopant molecules is commonly observed in dye-doped polymers, the shape changes of a molecule might not couple strongly to the host polymer through steric mechanical interactions, thus not contributing substantially to a macroscopic shape change. To gain insights into the effectiveness of such mechanical coupling, we directly probe the dopant molecules using dichroism measurements simultaneously while measuring the photomechanical response and find mechanical coupling to be small enough to make photothermal heating—mediated by the transfer of optical energy as heat to the polymer—the dominant mechanism. We also predict the fraction of light energy converted to mechanical energy using a model whose parameters are thermodynamic material properties that are measured with independent experiments. We find that in the thin-film geometry, these dye-doped glassy polymers are as efficient as any other material but their large Young’s modulus relative to other organic materials, such as liquid crystal elastomers, makes them suitable in applications that require mechanically strong materials. The mechanical properties and the photomechanical response of thin films are observed to be significantly different than in fibers, suggesting that the geometry of the material and surface effects might play an important role. Full article

The dyes used to produce two Palestinian garments from the British Museum’s collection attributed to the late 19th–early 20th century were investigated by high pressure liquid chromatography coupled with diode array detector and tandem mass spectrometry (HPLC-DAD-MS/MS). Palestinian embroidery is a symbol of national identity and the topic of scholarly research. However, little attention has been given to the dyes and how these changed with the introduction of new synthetic formulations in the second half of the 19th century. The results revealed the use of natural indigoid blue and red madder (Rubia tinctorum), in combination with tannins. Yellow from buckthorn (probably Rhamnus saxatilis) and red from cochineal (probably Dactylopius coccus) were found mixed with synthetic dyes in green and dark red embroidery threads, respectively. Early synthetic dyes were identified in all the other colours. These include Rhodamine B (C.I. 45170), Orange II (C.I. 15510), Orange IV (C.I. 13080), Metanil Yellow (C.I. 13065), Chrysoidine R (C.I. 11320), Methyl Violet (C.I. 42535), Malachite Green (C.I. 42000), Fuchsin (C.I. 42510), Auramine O (C.I. 41000) and Methyl Blue (C.I. 42780). As the date of the first synthesis of these dyes is known, the production date of the garments was refined, suggesting that these were likely to be produced towards the end of the 1880s/beginning of the 1890s. The continuous use of historical local sources of natural dyes, alongside new synthetic dyes, is of particular interest, adding rightful nuances to the development of textile-making practices in this region. Full article

Nanosized ceria (CeO₂) and a graphitic carbon nitride-loaded ceria (CeO₂/GCN) nanocomposite were synthesized using a straightforward and efficient method and characterized by XRD, FTIR, SEM, TEM, TGA, and BET analyses. These techniques confirmed that CeO₂ was effectively supported on the surface of GCN, with particle sizes of the CeO₂/GCN composite in the range of 10–15 nm and a pore size of 3.33 nm. The photocatalytic activity of the CeO₂/GCN nanocomposite and CeO₂ NPs in the degradation of methyl red dye under sunlight radiation was studied using UV–visible spectroscopy. A noticeable red shift in the CeO₂/GCN nanocomposite compared to pure CeO₂ NPs suggests a reduction in its band gap energy, calculated at 3.90 eV for CeO₂ NPs and 2.97 eV for the CeO₂/GCN nanocomposite. This band gap reduction enhances the photocatalytic degradation process, achieving a removal efficiency of 99.92% within a short irradiation time of 40 min for the CeO₂/GCN nanocomposite, compared to 69.47% for CeO₂ NPs. These findings indicate that graphitic carbon nitride significantly enhances the photocatalytic properties of CeO₂ NPs. Full article

This study is the first to convert two waste materials, waste rice noodles (WRN) and red mud (RM), into a low-cost, high-value magnetic photocatalytic composite. WRN was processed via a hydrothermal method to produce a solution containing carbon quantum dots (CQDs). Simultaneously, RM was dissolved in acid to form a Fe³⁺ ion-rich solution, which was subsequently mixed with the CQDs solution and underwent hydrothermal treatment. During this process, the Fe³⁺ ions in RM were transformed into the maghemite (γ-Fe₂O₃) phase, while CQDs were incorporated onto the γ-Fe₂O₃ surface, resulting in the CQDs/γ-Fe₂O₃ magnetic photocatalytic composite. Experimental results demonstrated that the WRN-derived CQDs not only facilitated the formation of the magnetic γ-Fe₂O₃ phase but also promoted a synergistic interaction between CQDs and γ-Fe₂O₃, enhancing electron-hole pair separation and boosting the production of reactive radicals such as O₂^·− and ·OH. Under optimized conditions (pH = 8, carbon loading: 10 wt%), the CQDs/γ-Fe₂O₃ composite exhibited good photocatalytic performance against methylene blue, achieving a 97.6% degradation rate within 480 min and a degradation rate constant of 5.99 × 10⁻³ min⁻¹, significantly outperforming RM and commercial γ-Fe₂O₃ powder. Beyond methylene blue, this composite also effectively degraded common organic dyes, including malachite green, methyl violet, basic fuchsin, and rhodamine B, with particularly high efficiency against malachite green, reaching a degradation rate constant of 5.465 × 10⁻² min⁻¹. Additionally, due to its soft magnetic properties (saturation magnetization intensity: 16.7 emu/g, residual magnetization intensity: 2.2 emu/g), the material could be conveniently recovered and reused after photocatalytic cycles. Even after 10 cycles, it retained over 98% recovery and 96% photocatalytic degradation efficiency, underscoring its potential for cost-effective, large-scale photocatalytic water purification. Full article