Search Results (128)

CuWO₄ films were prepared on FTO glass substrates by the hydrothermal method. To improve their photocatalytic activity, the CuWO₄ films were further modified with BiOI using the successive ionic layer adsorption and reaction (SILAR) method. Characterization results indicate that BiOI and CuWO₄ achieved nanoscale mixing and formed a Type II p-n heterojunction. The heterojunction formation not only extends the light absorption threshold of CuWO₄ from 530 nm to 660 nm but also enhances the light absorption capacity across the entire solar spectrum. More importantly, the heterojunction formation facilitates the separation and transfer of photogenerated carriers and inhibits the recombination of photogenerated electrons and holes, which is evidenced by the results of PL spectra, photocurrent density, and EIS spectra. Compared with individual CuWO₄ films, the photocatalytic activity of BiOI/CuWO₄ heterojunction films in degrading the organic dye MB is increased by up to 1.17 times. Additionally, BiOI/CuWO₄ heterojunction films exhibit certain activity in the photocatalytic degradation of polystyrene (PS) nanoplastics and are capable of reducing the average particle size of nanoplastics from 425 nm to 325 nm within 80 h. Full article

Conjugated microporous polymers (CMP) are advanced photocatalytic systems for degrading organic dyes. However, their potential and efficiency are often limited by rapid electron–hole pair (e⁻/h⁺) recombination. To overcome this limitation, this study proposes a strategy that involves designing a Mott–Schottky heterojunction and integrating graphene sheets with a near-zero bandgap into the CMP-1 framework, resulting in a non-covalent graphene/CMP (GCMP) heterojunction composite. GCMP serves two main functions: physical adsorption and photocatalytic absorption that uses visible light energy to trigger and degrade the organic dye. GCMP effectively degraded four dyes with both anionic and cationic properties (Rhodamine B; Nile Blue; Congo Red; and Orange II), demonstrating stable recyclability without losing its effectiveness. When exposed to visible light, GCMP generates reactive oxygen species (ROS), primarily singlet oxygen (¹O₂), and superoxide radicals (^•O₂), degrading the dye molecules. These findings highlight GCMP’s potential for real-world applications, offering a metal-free, cost-effective, and environmentally friendly solution for wastewater treatment. Full article

Nowadays, there is an urgent need for efficient photocatalysts and adsorbents for environmentally relevant applications. This study investigates the effect of polyaniline (PANI) on the structure and performance of carbonized nanocomposites composed of PANI and TiO₂ nanotubes (NTs), focusing on their photocatalytic degradation efficiency and dye adsorption capacity. The hypothesis was that PANI forms conductive carbon domains and stabilizes the anatase phase during thermal treatment, enhancing the performance of TiO₂-NTs as photocatalysts. Nanocomposites based on PANI and TiO₂-NTs (TTP) were synthesized through chemical oxidative polymerization of aniline (ANI) in the presence of TiO₂-NTs using two TiO₂/ANI molar ratios of 50 and 150 and subsequently carbonized at 650 °C, yielding CTTP-50 and CTTP-150. The novel CTTP composites and carbonized pristine TiO₂-NTs (CTNT) were characterized by various techniques, including TEM, UV-Vis diffuse reflectance, Raman spectroscopy, XRD, and TGA. Their performance regarding dye adsorption and photocatalytic degradation under visible light was evaluated with Acid Orange 7, Methylene Blue, and Rhodamine B. CTTP-150 exhibited the highest adsorption capacity and photodegradation rate, attributed to the synergistic effect of PANI, which stabilizes the TiO₂ phase and enhances visible-light absorption and adsorption. Full article

Recently, research and development in the field of dye-sensitized solar cells has been actively advanced, as the technology constitutes a potential alternative to silicon-based photovoltaic devices. Modification of the molecular structure of the dye can enhance the adsorption on the TiO₂ surface, improve the light absorption capacity, suppress the charge recombination, increase the electron injection rate, and thereby improve the overall performance of the solar cell. Carbazole and phenothiazine are rigid heterocyclic compounds containing nitrogen as a heteroatom with large π-conjugated skeletons. Phenothiazine differs from carbazole by the presence of sulfur as an additional electron-rich heteroatom. The inclusion of this heteroatom in the structure of the compounds can indeed improve the electron-donating properties, affect the conjugation, and thus affect the optical, electronic, and electrochemical properties of the chromophores as a whole. The difference in planarity when comparing carbazole with phenothiazine can be useful from several points of view. The planar structure of carbazole increases the degree of conjugation and the electron transfer capacity, which can increase the photocurrent of the cell. The nonplanar structure of phenothiazine helps to prevent π-stacking aggregation. This review comprehensively summarizes the progress in the field of synthesis of organic dyes for solar cells with an emphasis on the comparative analysis of two electron-donating moieties, carbazole and phenothiazine. In addition, the review describes in detail the relationship between the structure of the compounds (dyes), their properties, and the performance of solar cells. Full article

The tungsten (W)-modified TiO₂ films were fabricated on the fluorine-doped TiO₂ substrates using the sol–gel process. The influences of W dopant on the photovoltaic properties of the tungsten-modified TiO₂ DSSC were analyzed, too. The crystallization and dye absorption of tungsten-modified TiO₂ thin films increased more than those of the undoped TiO₂ thin films. Furthermore, the optimal performances of the V_oc, J_sc, fill factor, and efficiency of the DSSC with tungsten-modified TiO₂ thin films were 0.68 V, 16.28 mA/cm², 65.5%, and 7.03%, respectively. The enhancement was mainly due to the improved crystallinity and increased dye adsorption of the tungsten-modified TiO₂ thin films, which contributed to improving the efficiency of the dye-sensitized solar cell. Full article

Biochar is a carbon-rich, porous substance produced from the thermal degradation process of carbon-based materials, like biomass and other solid waste, in an oxygen-deprived environment. The type of parent material and the conditions for processing are the principal factors in determining the properties of biochar. Because of its diverse physicochemical properties, biochar has gained growing attention over the decades as a cost-effective, sustainable, and emerging material with potential applications in energy, agriculture, and environmental sectors like wastewater treatment. Two different parent materials, such as wheat bran and maple leaf, were pyrolyzed at three different temperatures (300 °C, 500 °C, and 700 °C). The resultant biochar was analyzed for its adsorptive potential for different contaminants. All the tested physicochemical property values of the maple (Acer) leaf biochar were found to be higher than wheat (Triticum) bran biochar except bulk density and the dye absorption potential. Based on the biochar physiochemical properties, the pyrolysis temperature of 700 °C was found to be the best for pyrolyzing these biomasses. Irrespective of the biochar types, pH 2.0 with a residence time of 90 min outperformed with an initial dye concentration of 0.05 mg/mL and a biochar application rate of 50 mg/mL. Furthermore, MLBC exhibited higher oil adsorption potential in comparison with that of WBC. The addition of WBC and MLBC to the polymer beads increases their dye absorption competence; therefore, this biochar can be a potential means of water treatment. Full article

A significant development has been the integration of natural elements with bio-based materials to produce entirely bio-based functional textiles. In this investigation, lycopene, derived from tomatoes, is used as a new natural red dye for silk. A suitable solvent was selected to precisely measure the lycopene content in silk. The stability of lycopene in a simulated dye bath was examined in relation to heating duration and pH values. Central composite design was employed to evaluate the impact of dyeing conditions on the color intensity of silk. The results showed that lycopene dissolves more efficiently in dichloromethane than in water or ethanol. UV–Vis absorption spectra, which remained nearly constant, indicate that lycopene retains its stability after being heated at 90 °C for 60 min or when the pH is between 3.2 and 6.2. Higher temperatures lead to increased lycopene adsorption, thereby enhancing color intensity. Based on the ANOVA analysis from the central composite design experiment, the most influential factor affecting color intensity is the concentration of lycopene, followed by temperature, and then pH. As the lycopene concentration increases, the color intensity and saturation of the dyed silk also increase. Although the lycopene-dyed silk shows good wash fastness, there is room for improvement in rub fastness. In summary, this study confirms the potential of using lycopene as a new natural red dye for silk. Full article

The toxicity of hazardous dyes like rhodamine B and heavy metal ions like lead warrants the need for wastewater remediation. We describe here the functionalization of cobalt-doped iron oxide (Co_0.1Fe_2.9O₄) magnetic nanoparticles (MNPs) with citrate moieties for the effective sequestration of rhodamine B dye and lead ions from contaminated water. Citrate-functionalized MNPs are prepared using a co-precipitation technique. For the uncoated MNPs, the hydrodynamic diameter and zeta potential are found to be 21 nm and ~45 ± 3.1 mV, respectively. The hydrodynamic diameters are found to increase to ~51, ~59, and ~68 nm for the MNPs functionalized with ~20, ~40, and ~60 mg/mL of citrate, respectively, whereas the corresponding zeta potentials are found to be ~−27.95 ± 3.5 mV, ~−32.5 ± 3.6 mV, and ~−33.9 ± 3.5 mV, respectively. The chemisorption of the citrate moieties over the MNPs cause the zeta potential to be negative, a phenomenon which is further verified from the citrate-specific absorption bands in the Fourier transform infrared (FTIR) spectra of the surface-functionalized MNPs. UV-visible spectrophotometry is employed to probe the MNP-aided elimination of rhodamine B dye and lead ions from aqueous media, where the absorption bands at ~554 nm and ~375 nm (for lead (II)-5-dimercapto-1,3,4-thiadiazole chelate) are utilized for quantitative analyses. These citrate-functionalized nanoparticles are found to successfully remove the toxic rhodamine B dye and lead ions from water, with removal efficiencies of ~93.7 ± 2.6% and ~90 ± 2.4%, respectively. The unbound -COO⁻ functional groups of the citrate-functionalized MNPs electrostatically interact with the cationic rhodamine B dye or lead (II) ions, thereby leading to the adsorption onto the surface-functionalized MNPs and the subsequent magnetic-field-assisted removal. The experimental findings show the efficacy of the citrate-functionalized cobalt-doped iron oxide MNPs for the sequestration of dye pollutants and lead ions from contaminated water. Full article

Industrial textile wastewater containing both heavy metals and dyes has been massively produced. In this study, semi-interpenetrating polymer network structures of sodium alginate (SA)/polyvinyl alcohol (PVA)/κ-carrageenan (CG) aerogel beads were synthesized for their simultaneous reduction. The SA/PVA/CG aerogel beads were synthesized through a cost-effective and environmentally friendly method using naturally abundant biopolymers without toxic cross-linkers. The SA/PVA/CG aerogel beads were spheres with a size of 3.8 $\pm$ 0.1 mm, exhibiting total pore areas of 15.2 m²/g and porous structures (pore size distribution: 0.04–242.7 μm; porosity: 93.97%) with abundant hydrogen bonding, high water absorption capacity, and chemical resistance. The adsorption capacity and mechanisms of the SA/PVA/CG aerogel beads were investigated through kinetic and isotherm experiments for heavy metals (Cu(II), Pb(II)), cationic dye (methylene blue, MB), and anionic dye (acid blue 25, AB)) in both single and binary systems. The maximum adsorption capacities of the SA/PVA/CG aerogel beads based on the Langmuir model of Cu(II), Pb(II), and MB were 85.17, 265.98, and 1324.30 mg/g, respectively. Pb(II) showed higher adsorption affinity than Cu(II) based on ionic properties, such as electronegativity and hydration radius. The adsorption of Cu(II), Pb(II), and MB on the SA/PVA/CG aerogel beads was spontaneous, with heavy metals and MB exhibiting endothermic and exothermic natures, respectively. Full article

In the context of increasing water scarcity and environmental pollution, this study investigates the synthesis and application of p(AA-Oco-AAm)-g-Citrus Sinensis Peel hydrogel (CSP hydrogel) to enhance soil water retention and remove organic dyes from wastewater. Hydrogels were prepared using a combination of acrylamide and acrylic acid, with the incorporation of citrus peel as a natural resource. The water absorption capacity of the hydrogels was evaluated, achieving a maximum retention rate of 477 g/g, significantly improving the water-holding ability of various soil types. Additionally, the hydrogels demonstrated a strong affinity for methylene blue, with an equilibrium adsorption capacity reaching 2299.45 mg/g, indicating their effectiveness in wastewater treatment. Kinetic and isothermal adsorption models were applied to analyze the adsorption dynamics, revealing a superior fit to the Langmuir model. The hydrogels maintained structural integrity and reusability over multiple cycles, underscoring their potential for sustainable agricultural practices and environmental remediation. This research highlights the dual benefits of utilizing agricultural waste for the development of eco-friendly materials while addressing critical challenges in water management and pollution control. Full article

With the rapid progression of industrialization, water pollution has emerged as an increasingly critical issue, especially due to the release of organic dyes such as methylene blue (MB), which poses serious threats to both the environment and human health. Developing efficient photocatalysts to effectively degrade these pollutants is therefore of paramount importance. In this work, titanium dioxide (TiO₂) was modified with the photosensitizer hemin and the hydroxyl-rich polymer polydopamine (PDA) to enhance its photocatalytic degradation performance. Hemin and PDA function as photosensitizers, extending the light absorption of TiO₂ into the visible spectrum, reducing its bandgap energy, and effectively promoting separation of photogenerated electron–hole pairs through conjugated structures. Additionally, the strong adhesion of PDA enabled the rapid transfer and effective utilization of photogenerated electrons, while its abundant phenolic hydroxyls increased MB adsorption on the photocatalyst’s surface. Experimental results demonstrated a significant enhancement in photocatalytic activity, with the 1%PDA/3%hemin/TiO₂ composite achieving degradation rates of 91.79% under UV light and 71.53% under visible light within 120 min, representing 2.22- and 2.05-fold increases compared to unmodified TiO₂, respectively. This research presents an effective modification approach and provides important guidance for designing high-performance TiO₂-based photocatalysts aimed at environmental remediation. Full article

Dye-sensitization is a promising strategy to improve the light absorption and photoactivity abilities of wide-bandgap semiconductors, like TiO₂. For effective water-splitting photoanodes with no sacrificial agents, the electrochemical potential of the dye must exceed the thermodynamic threshold needed for the oxygen evolution reaction. This study investigates two promising organic cyanoacrylic dyes, designed to meet that criterion by means of theoretical calculations. Both yellow-colored dyes were synthesized and characterized by optical and photoelectrochemical techniques, demonstrating strong light absorption in the visible region, suitable experimental reduction potentials, and adsorption from the organic solvent onto mesoporous TiO₂ layers. In addition, to promote immobilization in aqueous electrolytes, the dyes were hybridized with graphene oxide or multi-walled carbon nanotubes. Photoelectrochemical analysis of the dye-sensitized photoelectrodes demonstrated efficient charge transfer from the dyes to the TiO₂ photoanode under simulated solar light. While the starting photocurrent notably surpassed the blank TiO₂, a subsequent decay points to kinetic obstacles that still need to be overcome. Full article

Bentonite-supported TiO₂ (Montmorillonite (MMT)-TiO₂) and Cu₃TiO₅ oxides (MMT-Cu₃TiO₅) nanomaterials were synthesized via a facile and sustainable sol–gel synthesis approach. The XRD results indicate the presence of mixed phases, namely, TiO₂ anatase and a new semiconductor, Cu₃TiO₅, in the material. The specific surface area (S_BET) exhibits a notable increase with the incorporation of TiO₂ and Cu₃TiO₅, rising from 85 m²/g for pure montmorillonite to 245 m²/g for MMT-TiO₂ and 279 m²/g for MMT-Cu₃TiO₅. The lower gap energy of MMT-Cu₃TiO₅ (2.15 eV) in comparison to MMT-TiO₂ (2.7 eV) indicates that MMT-Cu₃TiO₅ is capable of more efficient absorption of visible light with longer wavelengths. The immobilization of TiO₂ and Cu₃TiO₅ on bentonite not only enhances the textural properties of the samples but also augments their visible light absorption capabilities, rendering them potentially more efficacious for adsorption and photocatalytic applications. The photocatalytic efficacy of both MMT-TiO₂ and MMT-Cu₃TiO₅ was evaluated through the monitoring of the degradation of Orange G, an anionic azo dye. The MMT-Cu₃TiO₅ photocatalyst was observed to induce complete degradation (100%) of the Orange G dye in 120 min when tested in an optimized reaction medium with a pH of 3 and a catalyst concentration of 2 g/L. MMT-Cu₃TiO₅ was demonstrated to be an exceptionally effective catalyst for the degradation of Orange G. Following the synthesis of the catalyst, it can be simply washed with the same recovered solution and reused multiple times for the photocatalytic process without the need for any chemical additives. Full article

An important contributor to environmental degradation is the industrial revolution, which has occurred in developed and developing nations. The present investigation aimed to tackle the escalating apprehensions regarding the discharge of various types of dyes from the paint, textile, and dyeing sectors. This research focuses on the adsorption performance of a newly developed system that uses cotton pod shell powder (CPSP) as a novel adsorbent to remove dye industry wastewater. The system has been designed, manufactured, and tested to be operationally efficient and cost-effective. The CPSP is a new adsorbent with desirable properties such as favorable functional groups and porosity, and analysis of its functional groups and porous nature was carried out using FTIR and SEM. The experimental data from the developed system showed that inlet dye concentration (50, 100, and 150 ppm), bed height (10, 20, and 30 cm), and flow rate (10, 15, and 20 mL/min) significantly affect the adsorption of dye industry wastewater by CPSP. Breakthrough curves were shown to be flow rate and bed depth dependent, according to the data. Significant experimentation was conducted on the developed system, and under optimized conditions. It was shown that the breakthrough point was affected by both bed height and flow rate. Evidence suggested that decreasing flow rate and concentration and raising bed height led to improved breakthrough and exhaustion times. At a concentration of 100 ppm and a flow rate of 15 mL/min, a bed depth of 20 cm was found to have the highest absorption capacity. Adam-Bohart, bed depth service time, and Yoon-Nelson models were utilized to examine the adsorption data. The results revealed that the developed system is effective, and the data obtained in this work can provide optimum operating conditions, suggesting its scalability to an industrial level for dye removal from wastewater by adsorption using CPSP as a novel adsorbent. Full article

Platanus officinalis fibers (PFs) taking advantage of high-availability, eco-friendly and low-cost characteristics have attracted significant focus in the field of biomaterial application. Polyethyleneimine grafted with polydopamine on magnetic Platanus officinalis fibers (PEI-PDA@M-PFs) were prepared through a two-step process of mussel inspiration and the Michael addition reaction, which can work as an effective multifunctional biomass adsorbent for anionic dye with outstanding separation capacity and efficiency. The as-prepared PEI-PDA@M-PFs possess desirable hydrophilicity, magnetism and positive charge, along with abundant amino functional groups on the surface, facilitating efficient adsorption and the removal of Eriochrome Black T (EBT) dyes from water. In addition to the formation mechanism, the adsorption properties, including adsorption isotherms, kinetics, and the reusability of the absorbent, were studied intensively. The as-prepared PEI-PDA@M-PFs achieved a theoretical maximum adsorption capacity of 166.11 mg/g under optimal conditions (pH 7.0), with 10 mg of the adsorbent introduced into the EBT solution. The pseudo-second-order kinetic and Langmuir models were well matched with experimental data. Moreover, thermodynamic data ΔH > 0 revealed homogeneous chemical adsorption with a heat-absorption reaction. The adsorbent remained at high stability and recyclability even after five cycles of EBT adsorption processes. These above findings provide new insights into the adsorption processes and the development of biologic material for sustainable applications. Full article