Search Results (314)

Photocatalytic oxidation technology harnesses solar energy for pollutant mineralization, presenting significant potential for environmental applications. A critical bottleneck remains the development of high-performance photocatalysts. This study centers on the non-metallic semiconductor material graphitic carbon nitride (g-C₃N₄). To overcome the inherent limitations of pristine g-C₃N₄, including limited surface area, rapid charge carrier recombination, and inadequate active sites, it implements surface engineering strategies employing acidic (H₂SO₄) or basic (K₂CO₃) agents to modulate microstructure, introduce defect sites (cyano/amino groups), and optimize bandgap engineering. These modifications synergistically enhanced photogenerated charge carrier separation efficiency and surface reactivity, leading to efficient dye degradation. Notably, the K₂CO₃-modified catalyst (g-C₃N₄-OH), synthesized with a mass ratio of m(g-C₃N₄):m(K₂CO₃) = 1:1, achieved 92.2% Rhodamine B degradation within 50 min under visible light, surpassing pristine g-C₃N₄ (20.6%), the optimized H₂SO₄-modified sample (g-C₃N₄-HS, 60.9%), and even template-synthesized g-C₃N₄-SBA (79.6%). The g-C₃N₄-OH catalyst demonstrated exceptional performance under both visible light and natural solar illumination. Combining facile synthesis, cost-effectiveness, superior activity, and robust stability, this work provides a novel approach for developing high-efficiency non-metallic photocatalysts applicable to dye wastewater. Full article

Donor–π–acceptor (D–π–A) dyes have garnered significant attention due to their unique optical properties and potential applications in various fields, including optoelectronics, chemical sensing and bioimaging. This study presents the design, synthesis, and comprehensive photophysical investigation of a series of ionic dyes incorporating five- and six-membered heterocyclic rings as electron-donating and electron-withdrawing units, respectively. The influence of the dye structure, i.e., (a) the systematically varied heteroatom (NMe, S and O) in donor moiety, (b) benzannulation of the acceptor part and (c) position of the donor vs. acceptor, on the photophysical properties was evaluated by steady-state and time-resolved spectroscopy across solvents of varying polarity. To probe solvatochromic behavior, the Reichardt parameters and the Catalán four-parameter scale, including polarizability (SP), dipolarity (SdP), acidity (SA) and basicity (SB) parameters, were applied. Emission dynamics were further analyzed through time-resolved fluorescence spectroscopy employing multi-exponential decay models to accurately describe fluorescence lifetimes. Time-dependent density functional theory (TDDFT) calculations supported the experimental findings by elucidating electronic structures, charge-transfer character, and dipole moments in the ground and excited states. The experimental results show the introduction of O or S instead of NMe causes substantial hypsochromic shifts in the absorption and emission bands. Benzannulation enhances the photoinduced charge transfer and causes red-shifted absorption spectra to be obtained without deteriorating the emission properties. Hence, by introducing an appropriate modification, it is possible to design materials with tunable photophysical properties for practical applications, e.g., in opto-electronics or sensing. Full article

Water pollution, a significant environmental issue, is growing more urgent. This study evaluated the effectiveness of adsorption and electrocoagulation methods in removing Ba-sic Blue 3 (BB3), a common dye used in the textile industry, from water. For the adsorption process, linden tree leaves—often used for health benefits in existing literature—were employed, while in the electrocoagulation (EC) method, an aluminum electrode was used. The results show that the optimal conditions for adsorption were an initial BB3 concentration of 5 mg/L, 50 mL of 0.9 g Tilia L. adsorbent, 60 min, 180 rpm, 30 °C, and pH 10, achieving a removal efficiency of 99.21%. The optimal conditions for electrocoagulation were 1 L of 15 mg/L initial BB3, a current density of 2.64 mA/cm², 15 mL of 0.2 M KCl, a reaction time of 90 min, a stirring speed of 100 rpm, and a pH of 10, resulting in a removal efficiency of 97.98%. The results indicate that linden leaves, a natural and sustainable material, showed a slightly higher removal percentage (99.21%) in the EC method over a shorter period (60 min). Conversely, the EC method also achieved a significant removal rate (97.98%, 90 min). In summary, both methods demonstrate strong BB3 removal capabilities and could help improve wastewater treatment processes. Full article

The microparticle-enhanced microfiltration is a technique that combines the use of microparticulate adsorbent material dispersed in aqueous solution and microfiltration membranes for the removal of ions and emerging contaminants with low energy consumption. Thus, the objective of this work was to synthesize an organoclay, BAPTES, based on bentonite and (3-aminopropyl)triethoxysilane for use as a semi-synthetic adsorbent material in the microparticle-enhanced microfiltration process for the removal of AR27 in aqueous systems. For this purpose, the obtained organoclay was structurally characterized by FTIR-ATR-FEDS, SEM-EDS, DLS, and thermal analysis. In addition, equilibrium adsorption and kinetic studies of AR27 were performed. The results showed a significant increase in the adsorption capacity of AR27 by organoclay (86.06%) compared to natural bentonite (2.10%), due to the presence of ionizable amino groups in the organoclay structure that promote electrostatic interactions with the dye. Furthermore, kinetic studies showed that the adsorption process follows a pseudo-first-order model and that the equilibrium data better fits the Temkin model, indicating a heterogeneous adsorption surface with different binding energies. The evaluation of enhanced microfiltration with BAPTES microparticles showed that the adsorption capacity obtained in continuous flow experiments (14.25–33.63 mg g⁻¹) was lower than that determined experimentally under equilibrium conditions (~39.5 mg g⁻¹), suggesting that the residence time of the analyte and the adsorbent in the filtration cell is a determining factor in the retention values obtained. In addition, desorption studies revealed that basic pH had a greater effect than the presence of salts and the use of ethanol, favoring the weakening of the AR27-BAPTES interaction. Finally, the results highlight the potential use of BAPTES microparticle-enhanced microfiltration in applications involving the treatment of contaminated industrial effluents. Full article

Sodium magadiite (Na-Mgd) was hydrothermally prepared and converted to its protonic (H-Mgd) form by reaction with hydrochloric (HCl) solution. The obtained products were studied as adsorbents for basic blue 41 (BB-41) removal from polluted aqueous solution. Na-Mgd and H-Mgd were characterized by different techniques. Powder X-ray (PXRD) diffraction data confirmed a pure Na-Mag phase and its conversion to acidic form (H-Mgd) with shift in d₀₀₁ value from 1.54 nm to 1.12 nm. X-ray fluorescence (XRF) data supported the exchange of Na cations by protons for H-Mag. ²⁹Si magic angle spinning nuclear magnetic resonance (MAS-NMR) indicated a change in the local environment of silicon nucleus when Na-Mgd was treated with HCl solution. The BB-41 removal dyes were investigated throughout the batch process. Effects of selected parameters, for example, the adsorbent dosage, pH of the BB-41 solution, pH of the H-Mag solid, and starting concentration, were explored. The equilibrium data were fitted to the Langmuir and Freundlich isotherm models. The maxima removal capacities of Na-Mgd and H-Mgd were 219 mg/g and 114 mg/g, respectively. The regeneration and reusability tests were performed using initial concentrations of 50 mg/L and 200 mg/L for seven cycles. The efficiency was maintained for 5 to 6 cycles with a decline of 10% using low initial concentration; however, a decline of efficiency to 30 to 50% was achieved when a higher initial concentration was employed after 3 to 4 regeneration tests for Na-Mgd and H-Mgd samples. Adsorber batch design using the Langmuir and Freundlich isotherm parameters was used to predict its performance for commercial usage. The predicted masses of H-Mgd were higher than those of Na-Mgd to treat different effluent volumes contaminated with 200 mg/L of BB-41 dyes at desired removal percentages. Full article

This study investigated the sorption properties of the biomass of larch (LaC), pine (PiC) and spruce cones (SpC) in relation to the anionic dye Reactive Black 5 (RB5) and cationic Basic Red 46 (BR46). The scope of the study included the properties of the sorbents (FTIR, SSA, fiber content, elemental analysis C, N, H, pH_PZC), the effect of pH on the sorption efficiency of the dyes, the sorption kinetics (pseudo-first-order model, second-order model, intraparticle diffusion model) and the maximum sorption capacity of the sorbents (Langmuir 1 and 2 models, Freundlich). The sorption efficiency of RB5 on the sorbents tested was highest at pH 2 and BR46 at pH 6. The pH_PZC values determined for LaC, PiC and SpC were 6.86, 7.02 and 7.19, respectively. The sorption equilibrium time depended mainly on the initial dye concentration and ranged from 150 to 180 min for RB5 and from 120 to 210 min for BR46. The sorption capacities (Q_max) of LaC, PiC and SpC for RB5 were 1.05 mg/g, 1.12 mg/g and 1.61 mg/g, respectively, and for BR46 were 70.53 mg/g, 76.60 mg/g and 96.44 mg/g, respectively. The most efficient sorbent for both dyes was SpC, which was partly related to the high lignin content of the material. Full article

Many industries release untreated synthetic dye effluents into water bodies, harming ecosystems and human health. Therefore, an economical and sustainable solution for treating dye-contaminated water must be developed. In this study, mulberry leaves (Morus nigra L.), as a cost-effective and sustainable adsorbent, were prepared to remove Basic Yellow 28 (BY28) and Basic Blue 3 (BB3) cationic dyes from industrial dye wastewater using adsorption. Batch experiments with key variables such as initial dye concentration, adsorbent dosage, contact time, temperature, stirring speed, and pH were conducted to find optimal conditions. The effectiveness of mulberry leaves as an adsorbent after multiple regeneration cycles was examined. The adsorbent was characterized through various instrumental methods, including FTIR, SEM, XRD, and BET analysis. Adsorption performance was analyzed using the Langmuir and Freundlich isotherm models. The results showed that the mulberry leaf adsorbent best fits the Langmuir model, with R² values of 0.999 for BY28 and 0.973 for BB3. The maximum adsorption capacities were 0.15 mg/g for BY28 and 7.19 mg/g for BB3, indicating their upper limits for dye uptake. The optimal conditions achieving removal efficiencies of over 99% were 1.5 g, 50 mL, 15 min, 180 rpm, and 10 mg/L at 30 °C for BY28 in neutral pH (7) and 1.5 g, 50 mL, 45 min, 100 rpm, and 30 mg/L at 40 °C for BB3 in basic pH (10). The regeneration of mulberry leaves as an adsorbent through acid treatment with 0.1 M HCl and 0.1 M CH₃COOH solutions maintained a high performance, achieving up to 98% dye removal efficiency after two regeneration cycles. It has been observed that successful results can be achieved in terms of reusability. Additionally, the removals of BB3 and BY28 performed in an ultrasonic-bath-assisted environment successfully achieved removal efficiencies of 84.87% and 75.41%, respectively. According to the results, mulberry leaves can effectively be used in wastewater treatment to remove dyes, can be reused multiple times, and thus serve as an environmentally friendly and sustainable adsorbent. Full article

This study has successfully developed a practical and straightforward approach for synthesizing nanocomposites with excellent dye removal potential. The SEM inspection of γ-Al₂O₃ (γ-Al) and MgO/MgAl₂O₄ (Mg/MgAl) nanocomposite showed a mean size of 59.0 and 46.4 nm, respectively, while the TEM results show particles with an average size of 26.63 and 13.4 nm, respectively. The surface area of γ-Al and Mg/MgAl was 50.0 and 69.5 m² g⁻¹, respectively. The study of adsorbing indigo carmine (IC) sorption onto γ-Al and Mg/MgAl presented sorption capacities of 41.6 and 55.9 mg g⁻¹, respectively, and both adsorbents attained equilibrium at 90 min. The highest IC sorption onto Mg/MgAl took place at pH 6.0. It is worth mentioning that raising the IC solution’s temperature from 20 °C to 50 °C increased the q_t to 268 mg g⁻¹. The IC sorption onto γ-Al and Mg/MgAl agreed with the pseudo-second-order model, and the liquid-film diffusion controlled the IC sorption. The Mg/MgAl showed an average removal of 98.2% when tested for removing six dyes at 10 mg L⁻¹, particularly malachite green, methylene blue, fast green, methyl orange, rhodamine B, and basic fuchsin, and the removal efficiency was 93.3% when their concentration increased to 20 mg L⁻¹. The Mg/MgAl nanocomposite performed exceptionally well in natural water samples (seawater and groundwater), indicating its potential applicability in managing water contamination. Full article

Biomimetic restorative treatments in pediatric dentistry increase the longevity of the restoration compared to traditional methods and aim to preserve the natural tooth structure. Prefabricated zirconia crowns have been developed as aesthetic alternatives to stainless steel crowns for full-coronal restorations of primary teeth. This study aimed to compare the fracture resistance and microleakage of two different posterior zirconia crown brands—NuSmile^® (USA) and ProfZrCrown^® (Turkey)—cemented with either conventional glass ionomer cement (GIC) or resin-modified glass ionomer cement (RMGIC). Eighty extracted primary molars were divided into four groups (n = 20). Crowns were cemented with Ketac™ Cem Radiopaque (GIC) or Ketac™ Cem Plus (RMGIC), in accordance with the manufacturers’ instructions, and then subjected to thermocycling. Fracture resistance was tested on 40 samples by applying an increasing compressive load until failure, with values recorded in Newtons (N). The remaining 40 samples were immersed in basic fuchsin dye for microleakage testing and evaluated under a stereomicroscope at 30× magnification. The results revealed that the ProfZrCrown^®/RMGIC group exhibited significantly higher fracture resistance compared to the NuSmile^®/RMGIC group (p < 0.05). No statistically significant differences were found among the other groups. Although no significant differences in microleakage were observed among the groups (p > 0.05), crowns cemented with GIC demonstrated higher microleakage levels. Within the limitations of this in vitro study, ProfZrCrown^® may be considered a promising alternative for aesthetic posterior restorations in pediatric dentistry. Full article

The terms fillenoert, villemort, feulje mort, and fillemot are obsolete historical color names derived from the French feuille morte (dead leaf), referred to a broad spectrum of brownish, yellowish, greenish, and reddish hues in early modern textile dyeing. This study investigates the visual identity and chromatic range of dead leaf by reconstructing dye recipes from seventeenth- and eighteenth-century European dyeing manuals. Using historically accurate materials and techniques, wool samples were dyed and analyzed through CIELAB color measurements to quantify their hue values. The results reveal that dead leaf does not correspond to a single, fixed color but represents a flexible and metaphorical category, reflecting both the natural variation in dead foliage and the diversity of historical dyeing practices. In early modern Europe, colors were often descriptive, frequently referencing the natural world or objects. These descriptors offered a nuanced vocabulary that extended far beyond today’s basic chromatic terms. Reworking these recipes reveals the complex interplay between chromatic language, material practices, and color perception. Historical color names served not merely as labels but encoded information about dye sources, cultural associations, and socio-economic contexts. Understanding and reviving this terminology deepens our appreciation of early dyeing traditions and bridges past and present conceptions of color. Full article

This review summarises the possible applications and basic methodologies for the synthesis of six-membered polyazo heterocycles, namely, diazines, triazines, and tetrazines. The time period covered by the analysed works ranges from the beginning of the 20th century to the present day. This period was chosen because it was during this time that synthetic chemistry, as defined by physicochemical research methods, became capable of solving such complex problems as efficiently as possible. The first part of the review describes the applications of polyazo heterocyclic compounds, whose frameworks are found in the composition of drugs, dyes, and functional molecules for materials chemistry, as well as in a wide variety of natural compounds and their synthetic analogues. The review also systematises the methods for assembling six-membered aromatic polyazo heterocycles, including intramolecular and sequential cyclisation, which determine the possible structural and functional diversity based on the presence and arrangement of nitrogen atoms and the position of the corresponding substituents. Full article

The motivation for increasing the efficiency of renewable energy sources is the basic problem of ongoing research. Currently, intensive research is underway in technology based on the use of dye-sensitized solar cells (DSSCs). The aim of this work is to investigate the effect of modifying the iodide electrolyte with liquid crystals (LCs) known for the self-organization of molecules into specific mesophases. The current–voltage (I-V) and power–voltage (P-V) characteristics were determined for the ruthenium-based dyes N3, Z907, and N719 to investigate the influence of their structure and concentration on the efficiency of DSSCs. The addition of a nematic LC of 4-n-pentyl-4-cyanobiphenyl (5CB) to the iodide electrolyte influences the I-V and P-V characteristics. A modification of the I-V characteristics was found, especially a change in the values of short circuit current (I_SC) and open circuit voltage (V_OC). The conversion efficiency for cells with modified electrolyte shows a complex dependence that first increases and then decreases with increasing LC concentration. It may be caused by the orientational interaction of LC molecules with the titanium dioxide (TiO₂) layer on the photoanode. A too high concentration of LC may lead to a reduction in total ionic conductivity due to the insulating effect of the elongated polar molecules. Full article

This study presents research on the production of activated biocarbons derived from herbal waste. Sage stems were chemically activated with two activating agents of different chemical natures—H₃PO₄ and K₂CO₃—and subjected to two thermal treatment methods: conventional and microwave heating. The effect of the activating agent type and heating method on the basic physicochemical properties of the resulting activated biocarbons was investigated. These properties included surface morphology, elemental composition, ash content, pH of aqueous extracts, the content and nature of surface functional groups, points of zero charge, and isoelectric points, as well as the type of porous structure formed. In addition, the potential of the prepared carbonaceous materials as adsorbents of model organic (represented by Triton X-100 and methylene blue) and inorganic (represented by iodine) pollutants was assessed. The influence of the initial adsorbate concentration (5–150 (dye) and 10–800 mg/dm³ (surfactant)), temperature (20–40 °C), and pH (2–10) of the system on the efficiency of contaminant removal from aqueous solutions was evaluated. The adsorption kinetics were also investigated to better understand the rate and mechanism of contaminant uptake by the prepared activated biocarbons. The results showed that materials activated with orthophosphoric acid exhibited a significantly higher sorption capacity for all tested adsorbates compared to their potassium carbonate-activated counterparts. Microwave heating was found to be more effective in promoting the formation of a well-developed specific surface area (471–1151 m²/g) and porous structure (mean pore size 2.17–3.84 nm), which directly enhanced the sorption capacity of both organic and inorganic contaminants. The maximum adsorption capacities for iodine, methylene blue, and Triton X-100 reached the levels of 927.0, 298.4, and 644.3 mg/g, respectively, on the surface of the H₃PO₄-activated sample obtained by microwave heating. It was confirmed that the heating method used during the activation step plays a key role in determining the physicochemical properties and sorption efficiency of activated biocarbons. Full article

The visual colorimetric sensing of total volatile basic nitrogen (TVB-N) allows for convenient dynamic monitoring of animal-derived food freshness to ensure food safety. The agarose hydrogel loaded with the natural dye juglone (Jug@AG) prepared in this study exhibits visible multicolor changes from yellow to grayish-yellow and then to brownish with increasing TVB-N gas concentration, achieving sensitive detection of TVB-N gas at concentrations as low as 0.05 mg/dm³ within 8 min. The minimum observable amounts of TVB-N in spiked pork and fish samples are 8.43 mg/100 g and 8.27 mg/100 g, respectively, indicating that the Jug@AG hydrogel possesses sensitive colorimetric sensing capability in practical applications. The Jug@AG hydrogel also shows significant changes in color difference value (∆C) under both room temperature (25 °C) and cold storage (4 °C) conditions, with the changing trends of ∆C showing consistency with the measured TVB-N and total viable counts (TVC) during the transition of pork and fish samples from freshness to early spoilage and then to spoilage. The results indicate that the Jug@AG hydrogel can be used as a colorimetric sensor to achieve real-time dynamic freshness monitoring of animal-derived food. Full article

The treatment with an alkali (sodium hydroxide) solution of acid-activated montmorillonite clay minerals resulted in a reduction in specific surface area. However, a significant enhancement in the removal of basic blue-41 dye solution was achieved compared to acid-activated samples only (first step of activation) and to the raw montmorillonite clay. The obtained products were characterized using different techniques. The results indicated that the acid-activated montmorillonites exhibited different physicochemical properties than the starting raw montmorillonite, with a reduction in the cation exchange capacity and improvements in the specific surface area (from 5 m²/g to 274 m²/g) and total pore volume (from 0.031 cm³/g to 0.450 cm³/g) due to the formation of the amorphous silica phase. However, the treatment with NaOH solution was accompanied by significant reductions in the specific surface area (from 274 m²/g to 18 m²/g) and total pore volume (from 0.450 cm³/g to 0.02 cm³/g) due to the dissolution of the formed amorphous silica phase, as confirmed through ²⁹Si MAS NMR and FTIR techniques. In addition, the SiO₂/Al₂O₃ molar ratios were close to those of the starting montmorillonite clay. The removal of the cationic basic blue-41 was optimized under different conditions, such as different initial concentrations, adsorbent doses, and pHs of the dye solution. The maximum removal capacities of acid-activated clays were in the range of 45 mg/g to 80 mg/g and decreased with the extent of the acid activation process. However, the capacities were enhanced after NaOH treatment and reached values in the range of 80 to 120 mg/g. Enhancing the surface area had less of an impact on the materials’ removal ability. The obtained materials performed well in seven adsorption–regeneration cycles, showing a 70% reduction in removal effectiveness. Full article