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One of the most important concerns in developing efficient heterojunction photocatalysts for the photodegradation of environmental contaminants is the enhancement and acceleration of photocarrier separation. In this study, novel nanocomposite photocatalysts of Ag–AgVO3 nanorods grafted with Zn0.5Mn0.5Fe2O4 metal ferrites nanoparticles were developed by using facial hydrothermal and coprecipitation techniques for the effective photodegradation of Rhodamine B (Rh B) under visible light exposure. The fabricated materials were analyzed in detail using scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDS), nitrogen adsorption/desorption, transmission electron microscopy (TEM), photoluminescence spectroscopy (PL), vibrating sample magnetometer, and ultraviolet–visible diffuse reflectance spectroscopy (DRS). The results showed an efficient contribution when compared to the earlier research. The TEM showed a hybrid of nanorods of supported composite with metal ferrite and Ag attached on the surface, consistent with field emission scanning electron microscopy and EDS results. The DRS expressed a lower band gap for supported nanocomposites (1.5 eV), which, arranged with PL, showed a lower recombination rate of supported nanocomposites. The surface properties showed that the supported hybrid might be as small as 45.42 nm or as large as 20.33 nm compared with others. When comparing the photocatalytic activity of pure AgVO3, Ag/AgVO3, and Zn0.5Mn0.5Fe2O4 photocatalysts, the performance of Ag–AgVO3/Zn0.5Mn0.5Fe2O4 nanocomposite photocatalyst was clearly superior (more than 99.9% degradation efficiency was achieved). The boosted activity the Ag–AgVO3/Zn0.5Mn0.5Fe2O4 photocatalyst system was justified by Z-system heterojunction induced by the plasmonic effect, and the suggested mechanism was investigated by quenching of reactive species by scavengers. The degradation performance was achieved under optimum conditions (pH = 2, 20 ppm of pollutant concentration, 120 mM of hydrogen peroxide, 1 g/L of catalysts dose). The results showed that after 240 min of visible irradiation resulted in the high (chemical oxygen demand) and (total organic carbon) reductions with a removal efficiency of (85) to (90%) for Rh B dye. The fabricated Ag–AgVO3/Zn0.5Mn0.5Fe2O4 nanocomposites were effective in the degradation of organic pollutants in wastewater treatment.

Over the past decade, safeguarding marine life and aquatic ecosystems against deleterious dye pollutants has emerged as a paramount concern. Methylene blue dye stands out as one such pollutant capable of inflicting irreversible damage to marine ecosystems even at minute concentrations. Addressing this pressing issue, we synthesized a novel CoMnFe2O4/graphene oxide nanocomposite employing a microwave-ultrasonic method. This composite, comprising soft superparamagnetic CoMnFe2O4 hollow microstructures integrated onto graphene oxide surfaces, revealed a mesoporous structure with a notably high surface area, which was about 96.4654 m2.g−1. Various analytical techniques were employed to scrutinize the crystal structure, functional groups, surface chemical composition, and morphologies of the synthesized CoMnFe2O4/graphene oxide nanocomposite (X-ray diffraction, Fourier-Transform Infrared Spectroscopy, energy-dispersive X-ray spectroscopy, field emission scanning electron microscopy, and high-resolution transmission electron microscopy). The CoMnFe2O4 crystal phase appears to be cubic in the X-ray diffraction with a 28.91 nm Avg. crystallite size. The measured band gap energies for the CoMnFe2O4, graphene oxide, and CoMnFe2O4/graphene oxide nanocomposite are 2.23 eV, 2.90 eV, and 1.89 eV, respectively. Remarkably, under visible light irradiation, the nanocomposite exhibited an impressive degradation efficiency of 97.54 % within just fifty minutes (at pH = 7, Methylene blue conc. = 15 mg/L, and catalyst dose = 0.05 g.), attributed to a photo degradation rate constant (k value) reaching 0.07330 min−1. Notably, this efficiency nearly doubled with the introduction of H2O2 peroxide. The outstanding recyclability of the CoMnFe2O4/graphene oxide nanocomposite, sustaining optimal performance over four cycles without significant degradation, underscores its potential for long-term environmental remediation efforts. Moreover, its magnetic extractability from contaminated solutions enhances its suitability for advanced environmental applications.

Abstract Three new chromophores based on difluoroborondipyrromethene dyes (Bodipy‐1, Bodipy‐2, and Bodipy‐3) are used as precursors to prepare luminescent solar concentrators (LSC) based on poly‐acrylate, following a thermally activated polymerization involving lauryl methacrylate as monomer, ethyl glycol dimethacrylate as cross‐linking agent, and lauroyl peroxide as initiator. The new dyes exhibit typical BODIPY absorption and emission properties in dichloromethane fluid solution, assigned to the lower‐lying singlet π–π∗ level, which in the case of Bodipy‐2 and Bodipy‐3, both containing diamino‐substituted styryl subunits in their structure, has a strong charge transfer contribution. The LSCs obtained starting from each of the three Bodipys are interfaced to silicon photovoltaic (PV) cells, and the PV light‐to‐energy conversion efficiencies ηopt for the three systems are calculated. The results yield ηopt of 4.53% for LSC‐Bodipy‐1, 5.26% for LSC‐Bodipy‐2, and 8.23% for LSC‐Bodipy‐3. The optical efficiency for LSC‐Bodipy‐3 is a remarkable value among the LSC based on organic dyes.

Synthetic organic dyes, which are resistant to biodegradation, pose a notable health risk, potentially leading to cancer and respiratory infections. Researchers have addressed this concern by exploring physicochemical methods to remove organic dyes from wastewater. A particularly promising solution involves modified biochar adsorbents, which demonstrate high efficiency in organic dye removal. Biochar, a charcoal-like material derived from biomass pyrolysis, offers advantages such as low cost, eco-friendliness, high efficiency and reusability. Beyond its role in sustainable soil remediation, biochar proves effective in removing organic dyes from wastewater after undergoing physical or chemical modification. Acid–base activation or metal–heteroatom impregnation enhances biochar's adsorption capacity. This comprehensive review examines the attributes of biochar, common methods for production and modification, and the impacts of raw materials, pyrolysis temperature, heating rate and residence time. It further elucidates the biochar adsorption mechanism in the removal of organic dyes, assessing factors influencing efficiency, including biochar feedstock, solution pH, adsorption temperature, particle size, initial dye concentration, biochar dosage and reaction time. It explores challenges, opportunities, reusability and regeneration methods of biochar in treating organic dye wastewater. It also discusses recent advances in organic dye removal using adsorption-based biochar. The review ultimately advocates for enhancing biochar's adsorption performance through post-modification.

Among numerous polluting compounds, the organic dyes and antibiotics are two servious factors causing water pollution. Hence, it is urgent to find a fast and safe way to degrade waste water in a sustainable approach. Here, ferroelectric heterostructure based on 2D Bi2MoO6 nanosheets and Bi2S3 nanorods has been prepared by a two-step solvothermal method for the reduction of organic dyes and antibiotics. Due to the energy band balance between Bi2S3 and Bi2MoO6, the formed type-II heterostructure can populate charge transfer at the junction and effectively inhibit electron-hole recombination. Under ultrasonic stimulation, catalytic active sites of a Bi2MoO6/Bi2S3 heterostructure for pollutant degradation can be generated through rapid charge transfer activation, thus enhancing the catalytic degradation effect of organic dyes and antibiotics. The Bi2MoO6/Bi2S3 heterostructure not only has good degradation effect, but also shows better stability. This work opens up new avenues for designing highly-efficient catalysts, which is of importance for wastewater degradation and energy-saving applications.

Advanced oxidation processes based on sulfate radical are considered one of the most promising wastewater treatment technologies currently. Among heterogeneous catalysts, cobalt metal–organic framework (MOF) has been widely reported. However, the inherent powder form of MOF hinders its practical application and reusability. Therefore, innovative methods to increase the loading capacity and the accessibility of MOF active sites in monolithic materials are required. Therefore, a simple and scalable method of fabricating a stable, hierarchical porous zeolitic imidazolate framework (ZIF‐67) 3D sponge by growing MOF on a short electrospun fiber network is shown. The sponge can efficiently activate peroxymonosulfate and rapidly degrade an exemplary organic dye (Rhodamine B) with a degradation efficiency of 100%. The resulting multilevel, hierarchical porous structure is beneficial to the mass transfer of reagents making the catalytic process efficient. This also enables the use of the ZIF‐67 as an efficient catalytic filter for continuous removal of dye. The sponge can be recycled and reused for several cycles due to its robustness without loss in efficiency. The proposed research strategy provides a new way to design MOF 3D monolithic materials.

Nanoparticles differ significantly from their bulk counterparts in terms of their characteristics, and they have a wide range of scientific uses. The use of green nanoparticles have received considerable attention. Recent advances in green nanomaterial production have made it possible to utilize these materials in catalysis. Many techniques have been applied to treat the textile wastewater. In the current study, Alizarin Red S dye is photocatalytically degraded utilizing green synthesized NiO nanoparticles derived from green tea extract. Utilizing techniques such as FT-IR, UV-Visible spectroscopy, EDAX, SEM, and XRD, the synthesized nanoparticles were examined. The morphology of the nanoparticle was studied using the SEM images. The XRD analysis was used to find the size of the crystal. The formula developed by Debye Scherer was used to determine the crystallite size. It was seen that the crystallite size was 29.75 nm. Using EDAX, the existence of Ni was verified. FT-IR analysis was used to find the functional groups present in the nanoparticle. According to morphological research, the nanoparticles are flake-shaped and have a larger surface area. Systematically the impact of many parameters on dye degradation, including catalyst dosage, dye concentration, and pH was examined. The findings showed that NiO can be used as a good nanocatalyst to degrade organic dyes. The kinetics of photodegradation were studied. Antibacterial and antifungal activities carried out on the synthesized nanoparticle and the precursor green tea shows that they have good activity over bacteria and fungi. The right selection of operating conditions allows to degrade the pollutant effectively.

The presence of organic dyes in aqueous environments is extremely hazardous to life due to the toxicity of these compounds. Thus, its removal from these various aquatic media is of the utmost importance, and several technologies are constantly being tested to meet this goal. Among these technologies, various types of degradation and adsorption techniques are typically used, and of the various types of materials used within these technologies, nanomaterials are constantly being developed and investigated, likely due to the various properties that these nanomaterials have. This work reviewed recent developments (in 2023) about the use of these nanomaterials in the treatment of solutions contaminated with these toxic organic dyes.

The ever-increasing expansion of chemical industries produces a variety of common pollutants, including colors, which become a global and environmental problem. Using a nanocatalyst is one of the effective ways to reduce these organic contaminants. With this in mind, a straightforward and effective method for the production of a novel nanocatalyst based on lignin-derived carbon, titanium dioxide nanoparticles, and Ag particles (TiO2/C/Ag) is described. The preparation of carbon and Ag particles (in sub-micro and nano size) was carried out by laser ablation in air. The nanocomposite was synthesized using a facile magnetic stirrer of TiO2, C, and Ag. According to characterization methods, a carbon nanostructure was successfully synthesized through the laser irradiation of lignin. According to scanning electron microscope images, spherical Ag particles were agglomerated over the nanocomposite. The catalytic activities of the TiO2/C/Ag nanocomposite were tested for the decolorization of methylene blue (MB) and Congo red (CR), employing NaBH4 in a water-based solution at 25 °C. After adding fresh NaBH4 to the mixture of nanocomposite and dyes, both UV absorption peaks of MB and CR completely disappeared after 10 s and 4 min, respectively. The catalytic activity of the TiO2/C/Ag nanocomposite was also examined for the reduction of 4-nitrophenol (4-NP) using a NaBH4 reducing agent, suggesting the complete reduction of 4-NP to 4-aminophenol (4-AP) after 2.30 min. This shows excellent catalytic behavior of the prepared nanocomposite in the reduction of organic pollutants.

Iron oxide nanoparticles were synthesized by co-precipitation using three different iron salt stoichiometric mole ratios. Powder X-ray diffraction patterns revealed the inverse cubic spinel structure of magnetite iron oxide. Transmission electron microscopic images showed Fe3O4 nanoparticles with different shapes and average particle sizes of 5.48 nm for Fe3O4-1:2, 6.02 nm for Fe3O4-1.5:2, and 6.98 nm for Fe3O4-2:3 with an energy bandgap of 3.27 to 3.53 eV. The as-prepared Fe3O4 nanoparticles were used as photocatalysts to degrade brilliant green (BG), rhodamine B (RhB), indigo carmine (IC), and methyl red (MR) under visible light irradiation. The photocatalytic degradation efficiency of 80.4% was obtained from Fe3O4-1:2 for brilliant green, 61.5% from Fe3O4-1.5:2 for rhodamine B, and 77.9% and 73.9% from Fe3O4-2:3 for both indigo carmine and methyl red. This indicates that Fe3O4-2:3 is more efficient in the degradation of more than one dye. This study shows that brilliant green degrades most effectively at pH 9, rhodamine B degrades best at pH 6.5, and indigo carmine and methyl red degrade most efficiently at pH 3. Recyclability experiments showed that the Fe3O4 photocatalysts can be recycled four times and are photostable.

The presence of organic dyes in wastewater raises significant environmental and human health concerns, owing to their high toxicity. In light of this, a novel adsorbent material with porous cryogel architecture was developed and employed for the effective removal of organic dyes from an aqueous solution. Initially, a titanium dioxide nanowire doped with zirconium HZTO was synthesized by the hydrothermal process. Subsequently, the beads (SA/HZTO) of sodium alginate and HZTO were successfully prepared through a cross-linking process, employing Ca2+ ions as the crosslinking agent. Structural analysis of SA/HZTO beads was performed using FTIR, SEM, and EDX techniques. We systematically examined the impact of different conditions, including the initial dye concentration, pH, contact time, and adsorbent dosage, on the adsorption process. Batch experiments, both in signal and binary systems, were conducted to rigorously assess the dye adsorption capabilities. Kinetic modeling revealed that the adsorption process adhered to the pseudo-second-order kinetic model. Remarkably, the prepared beads exhibited impressive adsorption capacities of 26 and 29 mg/g toward methylene blue (MB) and safranin (SF), respectively. SA/HZTO beads have demonstrated excellent adsorption properties, offering a promising avenue for the development of low-cost, efficient, and reusable adsorbent to remove dyes from wastewater.

This study highlights the recent advancements in organic electronic materials and their potential for cost-effective optoelectronic devices. The investigation focuses on the molecular design, synthesis, and comprehensive analysis of two organic dyes, aiming to explore their suitability for optoelectronic applications. The dyes are strategically constructed with carbazole as the foundational structure, connecting two electron-withdrawing groups: barbituric acid (Cz-BA) and thiobarbituric acid (Cz-TBA). These dyes, featuring carbazole as the core and electron-withdrawing groups, demonstrate promising spectral, optical, electrochemical, thermal, and theoretical properties. They show strong potential for diverse optoelectronic applications, promising efficient light absorption and robust stability. The results endorse their suitability for practical optoelectronic systems.

Alternate cobalt redox mediator based dye-sensitized solar cells (DSCs) are getting widespread attention taking advantage of their one-electron transfer mechanism compared to the conventional iodide/triiodide electrolyte. In the present study, we used indole fused heterocyclic organic sensitizers having indolo[3,2-b]indole as donor with three different π-spacers [(benzene (IID-1), thiophene (IID-2) and furan (IID-3)] along with cobalt bipyridine derivatives as redox mediators having different peripheral substituents {[Co(bpy)3]3+/2+, [Co(Me2bpy)3]3+/2+, and [Co(t-Bu2bpy)3]3+/2+}. A detailed investigation was carried out to understand the fundamental charge transfer processes and loss mechanism happening at the various interfaces as a function of structural variations in the present dye-electrolyte combinations. Among the investigated systems, higher performance was obtained for the association of furan substituted dye (IID-3) with [Co(t-Bu2bpy)3]3+/2+ electrolyte. The importance of choosing the right combination of sensitizer and electrolyte is critical to realize higher performance in dye-sensitized solar cells particularly while employing organic dyes and alternate metal complex redox electrolytes which was systematically investigated in the present manuscript.

In this study, a Cd-CeO2@C photocatalyst was produced via the calcination of a precursor (Cd-Ce(OH)4@AR14) obtained by co-precipitation of Ce(NO3)3·6H2O, Cd(NO3)2·4H2O and acid red 14 (AR14). The structure, composition, morphology, and optical properties of the synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectrum (FT-IR), Ultraviolet–Visible Diffuse Reflectance Spectroscopy (UV–Vis DRS), X-ray photoelectron spectroscopy (XPS) and Photoluminescence Spectroscopy (PL). The photocatalytic activity of the synthetized materials was evaluated by performing the degradation of AR14. The results showed that the band gap of CeO2 could be effectively reduced by Cd-doping, and that carbon bonds could decrease the recombination rate of photogenerated electrons and holes, resulting in enhancing the photocatalytic efficiency of the synthesized materials compared with that of pure CeO2. Hydroxyl groups play an important role in the photocatalysis because the adsorption of AR14 over Cd-CeO2@C is greatly affected by the content of hydroxyl groups. Moreover, effect of oxygen vacancies on the photocatalytic efficiency was investigated and the results showed that oxygen vacancies could improve the photocatalytic efficiency of the resulted samples.

This study describes the impact of surfactant molecular weights (PEG 2000 and PEG 4000) on the photocatalytic activity of TiO2 films, deposited via dip-coating from a PEG-stabilized suspension and silver-functionalized photo-fixation of Ag+ under UV illumination. The photocatalytic activity of pure and Ag/TiO2 films is assessed in the aqueous-phase degradation of Malachite green and Methylene blue in distilled and tap water under UV and visible illumination. The results indicate a positive effect of both the higher-molecular-weight non-ionic surfactant and Ag-functionalization yield higher photocatalytic efficiency. Notably, films photo-fixed with 10−2 M Ag+ show the highest degradation percentages in all experimental conditions. A direct correlation between the concentration of Ag+ ions and the enhancement of the photocatalytic activity is revealed: pure TiO2 < Ag, 10−4/TiO2 < Ag, 10−3/TiO2 < Ag, 10−2/TiO2. Flame atomic absorption spectrometry is used to study the Ag+ leeching from the Ag/TiO2 films. The structural properties of the nanostructures are investigated through scanning electron microscopy, Brunauer–Emmett–Teller analysis, energy-dispersive X-ray spectroscopy, and X-ray diffraction. Additionally, after three cycles of operation, Ag, 10−2/TiO2 (PEG 4000) films can maintain their photocatalytic activity, suggesting a potential application in the treatment of dye wastewater.

This comprehensive and quantitative research offers a thorough analysis of how metal oxides and nanocomposites are used in the photocatalytic treatment of organic dyes. It explores the challenges and opportunities of employing photocatalytic conversion technologies, discussing the optimal conditions for efficient degradation. The mechanisms of photocatalytic degradation are elucidated, highlighting the steps involved in transforming organic dyes into harmless by-products. Additionally, the article examines the factors that enhance the overall efficiency of photocatalytic conversion and compares its cost-effectiveness to other treatment methods. Various photocatalysts, with a focus on metal oxides and nanocomposites, are analyzed in terms of their advantages and limitations in degrading organic dyes. This article serves as a valuable resource for researchers and practitioners seeking sustainable and economical wastewater treatment solutions through efficient and eco-friendly photocatalytic approaches.

An experimental study is presented on the possibility of using the fluorescence from organic dyes as a broadband light source together with a monochromator for applications in excitation–emission matrix (EEM) fluorescence spectroscopy. A high-power single-chip light-emitting diode (LED) was chosen as an excitation source with a central output wavelength at 365 nm to excite a fluorescent solution of Coumarin 1 dye dissolved in ethanol. Two excitation configurations were investigated: direct excitation from the LED and excitation through an optical-fiber-coupled LED. A Czerny–Turner monochromator with a diffraction grating was used for the spectral tuning of the fluorescence. A simple method was investigated for increasing the efficiency of the excitation as well as the fluorescence signal collection by using a diffuse reflector composed of barium sulfate (BaSO4) and polyvinyl alcohol (PVA). As research objects, extra-virgin olive oil (EVOO), Coumarin 6 dye, and Perylene, a polycyclic aromatic hydrocarbon (PAH), were used. The results showed that the light-emitting-diode-induced fluorescence was sufficient to cover the losses on the optical path to the monochromator output, where a detectable signal could be obtained. The obtained results reveal the practical possibility of applying the fluorescence from dyes as a light source for food system analysis by EEM fluorescence spectroscopy.

Herein, the synthesis and optoelectronic properties of a novel push–pull organic dye, pRK1, specifically designed for use in dye‐sensitized photocathodes for hydrogen generation, are reported. The chemical structure of this dye, which incorporates a benzothiadiazole moiety, is inspired by RK1, a dye previously reported as a photosensitizer in n‐type dye‐sensitized solar cells (DSSCs) with power conversion efficiencies above 10% and high stability. The photoelectrochemical activity for hydrogen evolution of pRK1 after grafting onto NiO photocathodes in combination with a cobalt tetrapyridyl catalyst [Co(bapbpy)(OH2)2](BF4)2 in aqueous solution is evaluated and compared with two reference dyes from the literature, RuP2‐bpy and P1. It is shown that among the three photocathodes studied in this work, NiO|pRK1 is the most efficient, producing up to 1.9 μmol cm−2 of hydrogen with a faradaic efficiency of 66%, under visible light irradiation in aqueous electrolyte at pH 4.5. pRK1 shows a turnover number (TONdye) of up to 145 during the 6 h chronoamperometric test, almost twice that of P1. This study demonstrates that the chemical structure of high performance dyes commonly used in DSSCs can be successfully modified to meet the requirements for light‐driven water splitting in dye‐sensitized photoelectrochemical cells.

Photocatalytic ozonation, which combines the effects of lighting and ozonation, has been shown to enhance the decolorization and degradation of organic pollutants in wastewater. Dye solutions with concentrations of 10 ppm for both methylene blue and methyl orange dyes were used. The influence of ozoneation on the performance of photocatalytic activity of TiO2 and ZnO nanoparticles for the removal of organic dyes from aqueous solutions was investigated. To evaluate their efficacy for the removal of methylene blue and methyl orange dyes from aqueous solutions, the photocatalysts were exposed to UV light for 90 min, with ozone supplied either intermittently or continuously by an SDBD cold plasma reactor. The photocatalysts utilized in this study were characterized using SEM and XRD techniques. The degree of color degradation was determined using UV–Vis spectroscopy. The results demonstrate that TiO2 and ZnO nanoparticles exhibit different degrees of photocatalytic activity for the two dyes. The addition of ozone was found to enhance both the color degradation and mineralization rates of the pollutants, with intermittent ozonation proving more effective than continuous ozonation. The most significant color degradation results were obtained using TiO2 nanoparticles with intermittent ozonation for methylene blue dye (97 %) and ZnO nanoparticles with intermittent ozonation for methyl orange dye (40 %). Overall, this study provides evidence that photocatalytic ozonation represents a promising technique for water treatment.

The zinc oxide (ZnO) nanoparticle on a two - electron oxygen reduction reaction is a particularly promising candidate for in-situ application. Herein, we prepared the Cd doped ZnO nanocomposites through a simple hydrothermal method. The X-ray diffraction (XRD) analysis has been carried out to confirm the structure and size of the nanomaterial. The optical absorption and energy gap of the prepared nanoparticles have been identified by UV–vis-NIR studies. Photoluminescence (PL) studies on the synthesized nanomaterials confirm the characteristic existence of blue and green emission bands. Fourier transform infrared (FTIR) spectroscopy has been studied on the ZnO nanoparticles to analyze the -OH and CO-O vibrations. The structural and surface morphology analysis was inferred by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray (EDX) microanalysis. Cd doped ZnO nanocomposites are environmentally friendly and can be utilized to quickly remove contaminants from wastewater. The findings from the adsorption equilibrium fit the Brunauer-Emmett-Teller (BET) model very well, showing multi-layer adsorption. The photodegradation studies on Cd doped ZnO nanocomposites were carried out, which is an advanced oxidation process widely used for methylene blue removal. Therefore, the higher photocatalytic performance revealed that Cd doped ZnO nanocomposites could be a promising photocatalyst for environmental remediation applications.

The preparation of biochar capped magnetic nanoparticles as adsorbents for the removal of methylene blue (MB), bromophenol blue (BPB) and rhodamine B (RhB) dyes is reported. Morphological studies of the untreated magnetic biochar nanoadsorbent showed monodispersed particles of about 20 nm. Brunauer, Emmett and Teller (BET) analysis revealed surface area of 138.28 m2/g while saturation magnetization was 12.61 emu/g. The energy bandgap of pure magnetite was reduced from 4.03 to 2.70 eV after capping with biochar. Maximum adsorption capacity (Qo) of the dyes onto the magnetic biochar are 14.39, 16.47 and 2.65 mg/g for MB, RhB and BPB respectively. The Langmuir equation best interpreted the sorption of methylene blue while Freundlich equation was more suitable for the sorption of bromophenol blue and Rhodamine B dyes. FTIR spectra of the magnetic biochar nanoadsorbent after adsorption indicated that uptake of the organic dyes occurred through physisorption. Competitive adsorption studies indicate the sorption of methylene blue, and bromophenol blue dyes occurred in acidic medium in comparison to neutral and alkaline media. The result from the study also shows that ethanol is the best eluent for the desorption of the organic dyes and eluted about 70% of adsorbed dyes in the first run.

This study was undertaken to design a stable easy-recoverable nanoadsorbent (Fe3O4@CM-β-CDP@Tet-Cu(II)) hybrid with rich catalytic sites via wet-chemical method for the catalytic reduction of toxic dyes in wastewater. β-cyclodextrin (β-CD) with a hydrophilic character outside and hydrophobic inside cavity play an important role in catalytic reduction process by interacting with organic molecules and also prepared more sites for further surface modifications. Several characterization techniques including FT-IR, TGA analysis, FE-SEM/EDX, TEM, X-Ray diffraction patterns (XRD) measurements were employed to investigate the structural properties of the synthesized material. The catalytic ability of the obtained material was examined in the presence of different dyes including p-nitrophenol, Eosin Y, Rhodamine B, Congo red, and Methyl orange by UV–Vis spectroscopy as a simple and available method. Moreover, the parameters which effect on reduction process, such as dye and reducing agent (NaBH4) concentrations, mass of adsorbent and time were optimized at room temperature. The obtained data demonstrate the considerable catalytic ability of Fe3O4@CM-β-CDP@Tet-Cu (II) besides a remarkable reduction rate and high yield over a short reaction time, in particular for Methyl orange dye. Recycling experiments revealed that Fe3O4@CM-β-CDP@Tet-Cu (II) has an excellent stability wherein the catalyst was recycled five times with a slight decrease in the reduction ability without any remarkable change in morphological properties which confirm by FE-SEM analysis. The high catalytic activity, the magnetic recoverability, along with the excellent stability of Fe3O4@CM-β-CDP@Tet-Cu (II) make it a potential candidate for the reduction of multiple dyes in real wastewater samples.

In the present study, novel Mn2+Mn3+6[SiO4]O8 (braunite, MSO) nanostructures were fabricated by a simple and affordable sonochemical method. The uniformity, structure, shape, and size of the product are affected by sonication time and power. Mn2+Mn3+6[SiO4]O8 were used as a photocatalyst in the visible region due to their suitable bandgap (2.52 eV). The photocatalytic tests indicate that Mn2+Mn3+6[SiO4]O8 nanostructures can degrade organic dyes, such as Eriochrome Black T (EBT) and Erythrosine (ER) in high values. Therefore, the degradation rate is 94.8% under ideal circumstances, which include 70 mg of catalyst and 10 ppm EBT. According to the kinetics study, the superior rate constant (k = 0.0217 min−1) results in the maximum photocatalytic efficiency (94.8%). The recycle test unveils that Mn2+Mn3+6[SiO4]O8 is so stable and after five cycles, the photocatalyst efficiency decreased by 14.9 and 14.2% for EBT and erythrosine, respectively. Superoxide radicals were found to be the most active radicals implicated in the degradation of EBT and erythrosine by the scavenger's test.

Simultaneous presence of organic dyes with Cd(II) is possible and may affect Cd(II) removal from wastewater. This study involved various magnetic adsorbents for Cd(II) removal in the presence of various organic dyes (Tartrazine, Allura red, Rhodamine). Magnetic carbon nanotubes (MCNT), magnetic graphene oxide (MGO) and magnetic olive wood (MOW) were involved as adsorbents. The following adsorption issues were considered at various pHs: Effect of magnetic adsorbent type on Cd(II) uptake in presence and absence of Tartrazine; Effect of dye type on Cd(II) uptake by MCNT; Adsorption of organic dyes’ onto MCNT; Effect of other adsorption factors [“magnetite:CNT” mass ratio; “Cd: Rhodamine” molar ratio]. It was found that the presence of dyes caused an enhanced uptake of Cd(II) uptake by MCNT, which was attributed to suraface-dye-Cd ternary complex formation, in which Rhodamine caused the maximum Cd(II) uptake at pH 8. The maximum Cd(II) uptake conditions [using MCNT at pH 8 in (1:3) “Cd:Rhoadamine” molar ratio] gave Cd(II) adsorption capacity of 23 mg g−1. The method was re-useable, applicable on environmental waters and selective with a 20% decrease in its performance in presence of competing ions.

AbstractThe present review was provoked by the demand of a comprehensive overview on the recent scientific achievements revealing new horizons for advanced applications of organic dyes in service of contemporary medicinal chemistry, pharmacy and biomedicine. The review outlines the basic structural characteristics, physicochemical properties and biological activity of various dye families and suggests modified classifications of dyes according to their structural moieties and bioorganic functionalities serving the necessities of modern analytical chemistry and biochemistry. A major part of the review focuses on the pros and cons of the use of dyes as vectors in bioanalytic assays. The latter is based on comparative analyses of the limitations of some widely applied classical methodologies vs. the advantages and outcomes of the application of newly-designed dye molecules in modern dye-based bioassay techniques.

Due to a recent lack of clean water as a result of an increasing water demand, new wastewater solutions are required. Many researchers have looked into the removal of organic dyes from wastewater, with adsorption being an easy and effective method for removing organic and inorganic contaminants from contaminated water. Conjugated modified polymers, primarily polyaniline (Pani), have been widely used in the wastewater treatment because of their unique properties, such as easy synthesis, tunable morphology, porous structure, good electrorheological property, biodegradability, and nontoxic nature. Modified surface polymers are more reactive for the removal of dyes from wastewater and have outstanding dye removal capabilities in the wastewater treatment. This review article elaborates on wastewater treatment by utilizing silica gel-impregnated polyaniline nanocomposites as adsorbents. The use of polyaniline-modified silica gel in dye migration behavior to the most suited system for the resolution of co-existing dyes is referred to as the separation of organic dyes from their mixtures. Adsorption of important organic dyes to optimize conditions for efficient organic dye removal and comparison with another commercially available adsorbent. Chemical modification with the introduction of acidic or basic surface functionality could increase cationic and anionic chemical adsorption, as well as charged organic species such as dyes. The carrier is thus obtained with a chelating reagent on the surface of a silica gel after impregnation with polyaniline.

In recent years, the widespread use of synthetic dyes in various industries has led to significant water pollution. The removal of these dyes from wastewater is crucial for environmental protection and human health. In this study, we reported the adsorption properties of β-cyclodextrin derived polymer networks (CDPNs) towards organic dyes and CDPNs showed exceptional high selectivity. An independent gradient model based on Hirshfeld partition of molecular density (IGMH) method was applied to figure out the mechanism of the high selectivity. The adsorption kinetics, and isotherms were investigated to understand the adsorption mechanisms. Comprehensive studies on the reusability of the adsorbent were conducted to assess its potential for practical applications. Overall, this study provides insights into the potential use of CDPNs as an effective adsorbent for dye removal.

Photocatalysis by semiconductors is a favourable method for degrading toxic pollutants and dyes in water. However, the photocatalysts should have appropriate traits in order to be functional. Silver niobates, especially AgNbO3, are ternary metal oxides, which exhibit photocatalytic properties under visible light. The photocatalytic activity of AgNbO3 can also be improved by doping or coupling with other materials. Nevertheless, more studies are needed to further understand the properties of silver niobates and optimise its photocatalytic performance. The aim of this review is to highlight the significance of AgNbO3-based photocatalysts for use in photocatalytic dye degradation. As such, the recent development of AgNbO3 and AgNbO3-based materials has been discussed. Metal-doping of AgNbO3 has been shown to possess enhanced photocatalytic properties such as reduced band-gap energy and charge carrier recombination rate. Furthermore, AgNbO3-based photocatalysts are compatible with various materials in the formation of composites, including Ag nanoparticles and graphitic carbon nitride (g-C3N4). These composites, too, showed great promises in terms of photocatalytic dye degradation. This review also includes the potential areas of improvements to further enhance the applications of the silver niobate-based photocatalysts.

This review aimed to summarize the current knowledge regarding dibenzofulvene derivatives (DBF) investigated for photovoltaics and organic electronics applications. The work begins with a detailed analysis of the synthesis and modification methods for dibenzofulvene derivatives’ structure. Then, the physicochemical properties (thermal, electrochemical, and optical) of the selected compounds are discussed in detail. Moreover, this article also presents the DFT calculations performed so far. Finally, the review presents the latest research on the applications of dibenzofulvene derivatives as dyes for DSSC cells, hole transport materials (HTMs) for perovskite solar cells (PSCs), organic light-emitting diodes (OLEDs), and luminescent and electrochromic materials. Considering the above, this review may be helpful when designing new organic compounds for photovoltaic and organic electronic applications.

There is no doubt that organic dyes currently play an indispensable role in our daily life; they are used in products such as furniture, textiles, and leather accessories. However, the main problems related to the widespread use of these dyes are their toxicity and non-biodegradable nature, which mainly are responsible for various environmental risks and threaten human life. Therefore, the elimination of these toxic materials from aqueous media is highly recommended to save freshwater resources, as well as our health and environment. Heterogeneous photocatalysis is a potential technique for dye degradation, in which a photocatalyst is used to absorb light (UV or visible) and produce electron–hole pairs that enable the reaction participants to undergo chemical changes. In the past, various metal oxides have been successfully applied as promising photocatalysts for the degradation of dyes and various organic pollutants due to their wide bandgap, optical, and electronic properties, in addition to their low cost, high abundance, and chemical stability in aqueous solutions. Various parameters play critical roles in the total performance of the photocatalyst during the photocatalytic degradation of dyes, including morphology, which is a critical factor in the overall degradation process. In our article, the recent progress on the morphological dependence of photocatalysts will be reviewed.

This paper studies the composition and properties of shells of bivalve mollusks (Crenomytilus grayanus, Callista brevisiphonata, and Mizuhopecten yessoensis) from coastal discharges with a view to the possibility of their use in photocatalytic water treatment systems. The clam shells are considered in terms of application in the form of a powder material as a precursor for creating photocatalysts, and also as a carrier of photocatalytic coatings. It was shown that the main phase composing the shell material was calcium carbonate in two crystallographic modifications—calcite and aragonite. The presence of inorganic impurities in all studied clam shells did not exceed one mass percent. The main share was made up of elements included in the composition of calcium carbonate, which confirmed the high bio-indifference of the materials under study. Depending on the physiological and environmental features of the structure of clam shells, different contents of the organic component in their composition were observed. The granulometric characteristics of crushed clam shells (average diameter, specific surface area, and distribution modality) were studied. It was shown that the maximum values of bending strength of 5 MPa and compressive strength of 2 MPa are characterized by Mizuhopecten yessoensis shells with the lowest porosity of 2.91%. The features of sorption and photosorption processes of both whole and crushed shells in relation to four organic dyes at different temperatures and degrees of illumination were studied. Based on crushed shells of Mizuhopecten Yessoensis and titanium dioxide, functional materials (CaxTiyOz) were obtained, and their morphology and photocatalytic properties were studied. An example of the practical use of clam shells as a carrier of a photocatalytic coating is given.

Among the emerging photovoltaic (PV) technologies, Dye-Sensitized Solar Cells (DSSCs) appear especially interesting in view of their potential for unconventional PV applications. In particular, DSSCs have been proven to provide excellent performances under indoor illumination, opening the way to their use in the field of low-power devices, such as wearable electronics and wireless sensor networks, including those relevant for application to the rapidly growing Internet of Things technology. Considering the low intensity of indoor light sources, efficient light capture constitutes a pivotal factor in optimizing cell efficiency. Consequently, the development of novel dyes exhibiting intense absorption within the visible range and light-harvesting properties well-matched with the emission spectra of the various light sources becomes indispensable. In this review, we will discuss the current state-of-the-art in the design, synthesis, and application of organic dyes as sensitizers for indoor DSSCs, focusing on the most recent results. We will start by examining the various classes of individual dyes reported to date for this application, organized by their structural features, highlighting their strengths and weaknesses. On the basis of this discussion, we will then draft some potential guidelines in an effort to help the design of this kind of sensitizer. Subsequently, we will describe some alternative approaches investigated to improve the light-harvesting properties of the cells, such as the co-sensitization strategy and the use of concerted companion dyes. Finally, the issue of measurement standardization will be introduced, and some considerations regarding the proper characterization methods of indoor PV systems and their differences compared to (simulated) outdoor conditions will be provided.

This article presents the results of an assessment of the use of CdSe, NiCdSe, and CoCdSe thin films as a basis for photocatalysts used for the decomposition of the organic dyes rhodamine B, cargo red, and indigo carmine. Interest in this area was determined by the need to solve a number of issues related to increasing the efficiency purifying aqueous media from the negative effects of organic dyes, which cannot be disposed of using traditional methods associated with adsorption or filtration. The use of the electrochemical synthesis method to obtain thin films of a given thickness showed that the addition of nickel or cobalt sulfates to the standard electrolyte solution used to obtain CdSe films results in the formation of CdSe films with a higher degree of structural ordering (the crystallinity degree was more than 50%), as well as a decline in the band gap. When analyzing data on the photocatalytic decomposition of organic dyes, it was found that a change in the structure of the films due to the introduction of nickel and cobalt leads, in the case of the decomposition of the rhodamine B dye, to a more efficient decomposition, and in the case of the cargo red and indigo carmine dyes, not only to their complete decomposition and mineralization, but also to a reduction in the time of photocatalytic reactions (decomposition growth rate). Moreover, an analysis of cyclic tests demonstrated that NiCdSe and CoCdSe films maintain 90% of their photocatalytic decomposition efficiency compared to that achieved during the first decomposition cycle, while CdSe degrades after three consecutive cycles and its efficiency reduces by more than 2.5–3 times.

Pharmaceuticals have emerged as a new class of ecological pollutants and have majorly contributed to harmful effects on the environment and human health. The presence of these pharmaceuticals in wastewater treatment plants, ground, and seawater has been reported widely. Organic dyes and other organic contaminants which are being considered as emerging contaminants are now in the race among the top organic pollutants that need effective treatment. Removal of these contaminants via green adsorbents has become an essential requirement towards a green and cleaner environment. Herein, we report the efficacy of the novel greener porous graphene obtained via the near-green synthesis method as an adsorbent material for treating seven organic pollutants: Methyl orange, Methyl red, Rhodamine-B, Ciprofloxacin, Atenolol, Ibuprofen, and Carbamazepine. Batch tests were conducted to investigate the effect of adsorption time and varying adsorbent dosages. The obtained greener porous graphene showed fast kinetics, which was determined to be guided by pseudo second-order kinetics and the maximum pollutant removal efficiency (>80%) was seen at a high adsorbent dosage (2 mL injected from a 5 g/L solution). Furthermore, the nonlinear adsorption modeling confirmed that the greener porous graphene followed the Langmuir model for the dye rhodamine-B sorption and the Freundlich model for all the other six contaminants. This greener porous graphene can be considered an effective adsorbent for the removal of organic pollutants in wastewater.

The problem of industrial dyes depollution has pushed the scientific research community to identify novel photocatalysts with high performance. Herein, new photocatalysts composed of BaTiO3, BaTi0.96Cu0.04O3, BaTi0.96Cu0.02V0.02O3 and BaTi0.96Cu0.02Nb0.02O3 powders were prepared by solid-state reaction. The structural analysis of the samples confirmed the formation of the BaTiO3 structure. The splitting of (002) and (200) planes verified the formation of the tetragonal phase. The XRD peaks shifted, and the unit cell volume expansion verified the substitution of the Ti4+ site by Cu2+, V4+ and Nb5+ ions. The morphological measurements showed that the addition of (Cu, V) and (Cu, Nb) ions changes the particles’ morphology of BaTiO3, reducing its grains size. After the incorporation of (Cu, V) and (Cu, Nb) ions, the band gap of BaTiO3 was reduced from 3.2 to 2.84 and 2.72 eV, respectively. The modification of BaTiO3 by (Cu, Nb) ions induced superior photocatalytic properties for methyl green and methyl orange with degradation efficiencies of 97% and 94% during 60 and 90 min under sunlight irradiation, respectively. The total organic carbon results indicated that the BaTi0.96Cu0.02Nb0.02O3 catalyst has a high mineralization efficiency. In addition, it possesses a high stability during three cycles. The high photodegradation efficiency of Bi0.96La0.02Gd0.02FeO3 was related to the wide-ranging visible light absorption.

Herein, we report a green and facile preparation and characterization procedure of copper nanoparticles stabilized on magnetically separable sodium alginate support (Cu NPs-Fe3O4-SAlg) using Silybum marianum seeds extract and investigate their catalytic reductive chemistry for reduction of environmental pollutants. Indeed, the phytochemical content of the plant extract are responsible to biosynthesis of copper (Cu) nanoparticles and their stabilization by functionalizing the surface of magnetic alginate. Characterization of the biocatalyst was undertaken with FT-IR, XPS, XRD and STEM equipped with EDS. A standard suite of model compounds on which the reductive chemistry was tested were 4-nitrophenol (4-NP), potassium hexacyanoferrate (K3[Fe(CN)6]), and a variety of organic dyes including Congo Red (CR). The as-synthesized Cu NPs-Fe3O4-SAlg catalyst was highly effective in reducing 4-NP to 4-aminophenol in water and in the presence of sodium borohydride as a reducing agent. Also, a high reduction performance was observed with CR and K3[Fe(CN)6] in presence of the Cu NPs-Fe3O4-SAlg catalyst. The catalyst acted within 190 and 35 ​s respectively, at room temperature in the presence of NaBH4. Thus, the Cu NPs-Fe3O4-SAlg catalyst is a highly efficient catalyst which is also reusable due to its magnetic nature. This work reports a green synthesis of a high-performance Cu NPs-Fe3O4-SAlg catalyst using an environmental friendly method for reduction of 4-NP, CR, and K3[Fe(CN)6] over a short time.

Graphitic carbon nitride (g-C3N4) is a metal-free photocatalyst with visible light response. However, the disadvantages limit its application in a wider range, such as its small specific surface areas, fewer active sites, narrow visible light absorption range and high photogenic carrier recombination. In this paper, NaOH was used as activator for alkaline activation of g-C3N4. The phase composition, micromorphology, surface chemical state and optical properties of g-C3N4 after activation were tested. The photocatalytic performance of g-C3N4 over organic dyes was also tested. The results showed that Na+ entered the interlayers of g-C3N4, expanding the spaces between layers. The specific surface area and pore volume of powder were increased. The active sites were increased. The band gap was decreased, and the photogenic carrier recombination was reduced. Alkaline activated g-C3N4 had better adsorption and degradation performance over rhodamine B and methyl orange than inactivated g-C3N4. Therefore, the alkaline activated g-C3N4 promotes its further application in the field of wastewater treatment. This work sheds light on the material modification through a simple method with the aim to efficiently use solar energy.

Currently, the polluted wastewater discharged by industry accounts for the major part of polluted bodies of water. As one of the industrial wastewaters, dye wastewater is characterized by high toxicity, wide pollution, and difficulty in decolorization degradation. In this paper, a novel composite nanomaterial catalyst of silver was prepared by using Angelica sinensis polysaccharide (ASP) as a reducing and stabilizing agent. And the optimum reaction conditions explored are VAgNO3 = 5 mL (300 mM) and vASP = 7% (w/v) for 6 h at 90 °C. In addition, the ASP-Ag nanocatalyst was characterized by several techniques. The results demonstrated that ASP-Ag nanoparticles were successfully synthesized. Degradation rate, which provides a numerical visualization of the percentage reduction in pollutant concentration. With the wrapping of ASP, the ultrasonic catalytic degradation rates of different organic dyes including rhodamine B (RB), methylene blue (MB), and methyl orange (MO) were from 88.2%, 88.7%, and 85.2% to 96.1%, 95.2% and 93.5% at room temperature, respectively. After the experiments, when cdyes = 10 mg/L, the highest degradation rate can be observed under cAPS-AgNPs = 10 mg/L with the most powerful cavitation frequency f = 59 kHz. The effect of ultrasonic frequency on the acoustic pressure distribution in the reactor was investigated by using COMSOL Multiphysis@ software to propose the mechanism of ultrasonic degradation and the mechanism was confirmed by OH· radical trapping experiments. It indicates that OH· produced by the ultrasonic cavitation effect plays a determinant role in the degradation. And then, the intermediate products of the dye degradation process were analyzed by gas chromatography and mass spectrometry (GC–MS), and the possible degradation processes of dyes were proposed. The resulting products of degradation are SO42−, NH4+, NO3−, N2, CO2 and H2O. Finally, the recycling degradation experiments showed that catalyst maintains a high degradation rate within reusing 5 cycles. Thus, this catalyst is highly efficient and recyclable.

Semiconducting nanomaterials based heterogeneous photocatalysis represent a low-cost, versatile technique for environmental remediation, including pollution mitigation, energy management and other environmental aspects. Herein, we demonstrate the syntheses of various heterogeneous photocatalysts based on highly reduced graphene oxide (HRG) and vanadium oxide (VOx)-based nanocomposites (HRG–VOx). Different shapes (rod, sheet and urchin forms) of VOx nanoparticles were successfully fabricated on the surface of HRG under solvo-/hydrothermal conditions by varying the amount of water and ethanol. The high concentration of water in the mixture resulted in the formation of rod-shaped VOx nanoparticles, whereas increasing the amount of ethanol led to the production of VOx sheets. The solvothermal condition using pure ethanol as solvent produced VOx nano-urchins on the surface of HRG. The as-prepared hybrid materials were characterized using various spectroscopic and microscopic techniques, including X-ray diffraction, UV–vis, FTIR, SEM and TEM analyses. The photocatalytic activities of different HRG–VOx nanocomposites were investigated for the photodegradation of methylene blue (MB) and methyl orange (MO). The experimental data revealed that all HRG–VOx composite-based photocatalysts demonstrated excellent performance toward the photocatalytic degradation of the organic dyes. Among all photocatalysts studied, the HRG–VOx nanocomposite consisting of urchin-shaped VOx nanoparticles (HRG–VOx-U) demonstrated superior photocatalytic properties towards the degradation of dyes.

In this study, biocarbon was obtained from the waste material corn digest. Carbon adsorbents were obtained by physical activation of the precursor with CO2. Detailed physicochemical characterization of the biocarbon was carried out using low-temperature nitrogen adsorption/desorption, Boehm titration, zero-charge point (pHpzc) and iodine number. In addition, the sorption capacity of the biocarbon agents towards an aqueous solution of methylene blue and methyl red was determined, and the kinetics of the adsorption process were determined. The biocarbon adsorbents were characterized by an average developed specific surface area covering the range from 320 to 616 m2/g. The sorption capacity of the biocarbon adsorbents against methylene blue ranged from 40 mg/g to 146 mg/g, and for methyl red it covered the range from 31 mg/g to 113 mg/g. It was shown that the efficiency of organic dye removal by the obtained biocarbons depends on the initial concentration of the adsorbate solution, its mass, shaking rate, adsorbent–adsorbate contact time and temperature. The results obtained from the Langmuir and Freundlich kinetic models showed that the Langmuir model is the most suitable model for describing the adsorption of the studied pollutants on biocarbon. In turn, the adsorption kinetics of dyes is described according to the pseudo-second-order model. Adsorption studies also showed that as the process temperature increases, the removal efficiency of methylene blue and methyl red increases.

Metal ion doping is the most widely used means to improve the photocatalytic performance of semiconductor materials, which can adjust the band gap, broaden the range of optical response and construct impurity levels. The high efficiency modified NaTaO3 perovskite catalyst with good structural and catalytic properties was synthesized by a simple hydrothermal reaction method. A variety of analysis and testing techniques, such as XRD, SEM, DRS, XPS and EPR, were used to analyze the structure properties of the prepared materials. The results show that the influence mechanism of different metal introduction on the structure and properties of the NaTaO3 perovskite was different. Metal doping promoted the bond angle of Ta-O-Ta close to 180°, which restrains the recombination of the photogenerated electron-holes in the crystal. As Ce is introduced into the perovskite, the CeO2 forms and agglomerates around the perovskite, which improves the electron transport performance. With the narrower band gap, the Ce-modified perovskite shows that the degradation rate of ARS is 84% after 180 min of photoreaction. The species of h+, O2− and ·OH play different roles in improving the performance of the photocatalytic degradation process.

Titanium dioxide (TiO2) is an ideal photocatalyst candidate due to its high activity, low toxicity and cost, and high chemical stability. However, its practical application in photocatalysis is seriously hindered by the wide band gap energy of TiO2 and the prone recombination of electron-hole pairs. In this study, C, N doped TiO2 were supported on spent coffee grounds-derived carbon (ACG) via in situ formation, which was denoted as C, N–TiO2@ACG. The obtained C, N–TiO2@ACG exhibits increased light absorption efficiency with the band gap energy decreasing from 3.31 eV of TiO2 to 2.34 eV, a higher specific surface area of 145.8 m2/g, and reduced recombination rates attributed to the synergistic effect of a spent coffee grounds-derived carbon substrate and C, N doping. Consequently, the optimal 1:1 C, N–TiO2@ACG delivers considerable photocatalytic activity with degradation efficiencies for methylene blue (MB) reaching 96.9% within 45 min, as well as a high reaction rate of 0.06348 min−1, approximately 4.66 times that of TiO2 (0.01361 min−1). Furthermore, it also demonstrated greatly enhanced photocatalytic efficiency towards methyl orange (MO) in the presence of MB compared with a single MO solution. This work provides a feasible and universal strategy of synchronous introducing nonmetal doping and biomass-derived carbon substrates to promote the photocatalytic performance of TiO2 for the degradation of organic dyes.

Wool-coiled MoSrOS bimetal oxysulfide catalysts were synthesized by a simple method. The catalysts were characterized by different instruments. The MoSrOS reduction activities were also investigated by the reduction of Cr(VI), Rhodamine-B (RhB), Methyl orange (MO), Methylene blue (MB) and 4-nitrophenol (4-NP). The results showed that 100 mL (20 ppm) of 4-NP was completely reduced into 4-aminophenol (4-AP) in 20 min. Moreover, 100 mL (20 ppm) of MB, 100 mL (50 ppm) of RhB, 100 mL (50 ppm) of MO and 100 mL (50 ppm) of Cr(VI) were completely reduced within 6, 20, 40, and 30 min, respectively, by MoSrOS-2 bimetal oxysulfide catalyst. Hence, the wool-coiled MoSrOS bimetal oxysulfide catalysts could be used in the detoxification of toxic organic and inorganic pollutants.

Abstract Background Increasing the yield of nanomaterials using the same reactor size and fixing most of the reactants and conditions will greatly improve the production process by saving time, energy and efforts. Titanate nanotubes are mainly prepared by hydrothermal process, in which TiO2 powder reacts with NaOH at certain conditions to form the desired nanotubes. It was reported that it is a must to use high concentrations of NaOH (10 N) to enable the tubular form formation, and the amount of NaOH from the stoichiometry point of view is much higher than that of TiO2; this means excess amounts of NaOH are not used and washed off. This work was designed to improve the production yield by making use of this excess amount of NaOH. Results More than 60 g of sodium titanate nanotubes was prepared using simple hydrothermal method. The prepared nanotubes were characterized by X-ray powder diffraction, high-resolution transmission electron microscopy, Fourier-transform infrared spectroscopy and BET surface area analysis. The adsorption capacity of these nanotubes was tested against three commonly used dyes: methyl orange, crystal violet and thymol blue. The samples showed great affinity toward crystal violet and lower activity toward methyl orange and thymol blue, where they achieved more than 90% removal efficiency under different experimental conditions. Conclusions Sodium titanate nanotubes were prepared in large amounts using modified hydrothermal method. The obtained nanotubes efficiently removed crystal violet from water. This improved synthesis of titanate nanotubes will reduce the total cost of nanomaterials production, and subsequently the treatment process, since titanate nanotubes are used in adsorption and photocatalysis processes.

In this study, quantum chemical calculations of phenazine-based organic molecules applied in organic dye-sensitized solar cells (DSSCs) have been made and interpreted. Since DSSC molecules work with the electron push–pull system, the sequence of other compounds (2–8) from compound 1 is designed as a donor–π bridge (weak acceptor)–acceptor (D–π–A). Later, the studied molecules were expanded from 2a to 8c by lengthening the conjugation with phenyl, thiophene, and furan to the acceptor parts. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations are practiced to investigate all structures and absorption spectra of molecules, respectively. It has been observed that the phenazine-based molecule series are good candidates for DSSCs, both with their band gap and their absorption spectrum results. It can be assumed that changing the HOMO and LUMO energy values of all designed structures according to compound 1 can absorb light in the organic dye-sensitized solar cells and transfer electrons to the conductivity band of TiO2. As a result, it has been resolved that various dyes can be designed for dye-sensitizing solar cells by calculating electronic energies, HOMO–LUMO energies, and absorption wavelengths.

Optical imaging in the second near-infrared (NIR-II) window has attracted interest in recent years because of the merits of reduced light scattering, minimal autofluorescence from biological tissues and deeper penetration depth in this wavelength range. In this review, we summarize NIR-II organic contrast agents reported in the past decade for photoacoustic and fluorescence imaging including members of the cyanine family, D-A-D structure dyes, phthalocyanines and semiconducting polymers. Improved imaging contrast and higher resolution could be favorably achieved by rational design of NIR-II fluorophores by tuning their properties including molar extinction coefficient, fluorescence quantum yield, emission wavelength and others. A wide variety of applications using NIR-II dyes has been realized including imaging of tumors, lymphatics, brains, intestines and others. Emerging applications such as targeted imaging and activable imaging with improved resolution and sensitivity have been demonstrated by innovative chemical modification of NIR-II dyes. Looking forward, rational design of improved NIR-II dyes for advanced bioimaging is likely to remain an area of interest for next-generation potential approaches to disease diagnosis.

In this research, a perovskite-type neodymium cobaltite (NdCoO3) was successfully fabricated by a facile and affordable co-precipitation method. Different surfactants and solvents, such as ethylene glycol, water, and ethanol, were also applied throughout this preparation for morphological studies. The outcomes demonstrated that homogenous morphology was obtained in the presence of ethylene glycol and sodium dodecyl sulfate (SDS) with an average diameter of 51.8 nm. Based on the results of UV-Vis spectroscopy, NdCoO3 has a relevant bandgap (2.84 eV) associated with the visible region and can be used as a catalyst in the photodegradation procedure. The photocatalytic performance data showed that this compound has a high ability to degrade cationic (malachite green 79.7%) and anionic (phenol red 75.2%) dyes in high value. We investigated the effect of several parameters, such as dye types, dye concentration, and Nd2O3 as a by-product on the efficiency. The scavenger test has shown that •O2− plays a major role in degradation. The kinetic studies have shown that the higher reaction rate constants (k = 0.013 min−1) provide the best photocatalytic performance.

Abstract Commonly exhibited in museum galleries, animal mummies have been the focus of interest of both visitors and researchers alike. The study of these animal remains not only provides new insights into embalming techniques, but also brings a unique perspective on religious, social and economic practices. Twenty animal mummies are discussed in this study, including cats, ibises, crocodiles, calves and birds of prey from the collections of the British Museum (London, UK) and the Museo Egizio (Turin, Italy). The external textile wrappings encasing the mummified body of the animals were investigated with the main aim of identifying the colourants used. In fact, these are mostly patterned using undyed and coloured (mostly red, brown and black) linen strips. Broadband multispectral imaging (MSI) was initially carried out to obtain preliminary information at the macro-scale on the distribution and chemical nature of the colouring agents. Fibre optic reflectance spectroscopy (FORS) was then used to survey several coloured areas of the textile wrappings. Safflower (Carthamus tinctorius) and red ochre were identified non-invasively. Representative samples were then taken and observed using optical microscopy (OM) and scanning electron microscopy (SEM), in order to obtain information at the micro-scale on the distribution of the colouring agents on the fibres, as well as the presence of other materials, including those from environmental contamination. Energy dispersive X-ray spectrometry (EDX) revealed the elemental composition of particles and clear areas of the fibres, whereas high performance liquid chromatography tandem mass spectrometry (HPLC–MS/MS) provided the identification of the organic dyes at a molecular level. The use of hydrolysable and condensed tannins, in combination with iron as a mordant, was found to be used in the very dark shades, which generally corresponded to the textiles with the worst state of preservation. Nevertheless, other aspects, such as fibre processing and bleaching, fungal attack and presence of coating materials appeared to play a role in the evaluation of the conservation state of these textiles. The characterisation of the dyes and the additional inorganic materials contributed to elucidating the production technology of the colours used for animal mummification, and provided insights into ancient dyeing methods.

A magnetic porous carbon composite (MPC) was prepared from metal−organic frameworks (MOFs) by the one-step calcination method. The MPC was characterized by SEM, TEM, TG, DTG, Raman and XPS. The adsorption and degradation performance of MPC towards four organic dyes were investigated. The maximum adsorption amount of magenta on MPC was 191.94 mg g-1 at 25 °C. Furthermore, the MPC showed remarkable stability for it can be recycled 5 times through the facile magnetic separation without obvious loss of activity. The degradation efficiency of MPC toward four kinds of organic pollutants was nearly 100% within 36 ​min, which was much higher than that previously reported.

Electrospinning is a cost-effective and efficient method of producing polymeric nanofibre films. The resulting nanofibres can be produced in a variety of structures, including monoaxial, coaxial (core@shell), and Janus (side-by-side). The resulting fibres can also act as a matrix for various light-harvesting components such as dye molecules, nanoparticles, and quantum dots. The addition of these light-harvesting materials allows for various photo-driven processes to occur within the films. This review discusses the process of electrospinning as well as the effect of spinning parameters on resulting fibres. Building on this, we discuss energy transfer processes that have been explored in nanofibre films, such as Förster resonance energy transfer (FRET), metal-enhanced fluorescence (MEF), and upconversion. A charge transfer process, photoinduced electron transfer (PET), is also discussed. This review highlights various candidate molecules that have been used for photo-responsive processes in electrospun films.