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In 1540, in Ingolstadt, Germany, the influential astronomer and printer Peter Apian produced the Astronomicum Caesareum: a printed and hand-coloured astronomical book visualising the Ptolemaic universe through the use of diagrams and wheelcharts, worthy of his imperial patron, Charles V. About 130 copies have survived to this day, with varying degrees of paper quality and level of decoration, and only eleven volumes are considered deluxe copies. We thoroughly analysed one deluxe volume held at the Fitzwilliam Museum, Cambridge, and compared the results with four (one deluxe and three standard) other copies from institutions in the UK. A non-invasive analytical protocol was applied, including extensive microscopy, fibre-optic reflectance spectroscopy (FORS), X-ray spectroscopy (XRF), macroscale XRF (MA-XRF) and Raman spectroscopy. The most interesting pages were chosen based on art-historical evidence and the variety of the colour palette, including on volvelles (wheelcharts) and coats of arms. Following a systematic approach, we analysed the same pages in each volume, gathering information on the colour palette in all the volumes. The type of paper and the presence of watermarks were also documented. A wide range of materials was identified in the five copies, including red, purple and yellow organic dyes, lead white, verdigris, vermilion, azurite, indigo, smalt, and lead–tin yellow. Mosaic gold was used to embellish certain paint passages in the deluxe volumes and metals (gold and silver) were applied on some pages. The comprehensive findings were essential to identify specific traits related to Apian's workshop, to differentiate deluxe from standard copies, to suggest an order of production of the copies, and to provide new information on this landmark book and more generally in an under-researched field of study. [ABSTRACT FROM AUTHOR]

Azo compounds find use in many areas of science, displaying crucial properties for important applications as photoconductive organic pigments, fluorescent quenchers, paints, cosmetics, inks, and in the large and valuable dye industry. Due to the unstable intermediates, and the exothermic and fast reactions used in their synthesis, high value azo compounds are excellent candidates for continuous flow manufacturing. This comprehensive review covers the progress made to date on developing continuous flow systems for azo synthesis and reflects on the main challenges still to be addressed, including scale up, conversion, product purity, and environmental impact. The further development of integrated continuous flow processes has the potential to help tackle these challenges and deliver improved methods for azo compound generation. [ABSTRACT FROM AUTHOR]

Organic dyes can inflict environmental harm and pose risks to human health, thereby presenting challenges in their treatment within industrial wastewater. Currently, numerous research groups have conducted investigations on the adsorption of organic dyes in industrial wastewater. Herein, this work focuses on the selective adsorption approach towards dyes molecules based on an Anderson-type polyoxometalate (noted as POM-1) as potential adsorbent, which has been functionalized with organic ligands to enhance its negative charge. Adsorption experiments revealed that POM-1 displayed efficient adsorption capabilities towards the cationic dye methyl blue with almost complete adsorption within 25 min, and the adsorption rate was calculated as 98%. A rapid and consecutive filtering experiments have also been performed and further proved the excellent adsorption behavior of POM-1 towards MB. [ABSTRACT FROM AUTHOR]

Dyes can be determined as a substance that creates many environmental issues leading to the death of aquatic life, plants and all living organisms. Dye removal can be done by several physical, chemical and biological methods, including the photocatalytic method. Photocatalysis is a method in which light energy is used to degrade the dye. This technique is low-cost and eco-friendly, and it degrades many harmful substances from organic dyes compared to other techniques. The prime aim of the present work is to degrade the largely used organic dyes such as methylene blue, malachite green and crystal violet using EDTA-doped FeZnS2 and Leishman stain-doped FeZnS2 thin films. The doped FeZnS2 thin films were fabricated using the co-precipitation method. Thin fabricated films are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and UV–Visible spectroscopy (UV). These characterization studies show an active photo response indicating effective dye degradation. Based on the absorption studies of UV spectroscopy measurements after 60 min, the degradation efficiency of methylene blue, crystal violet and malachite green using EDTA-doped FeZnS2 are 76, 85 and 90, respectively. Similarly, the degradation efficiency after 60 min of methylene blue, crystal violet and malachite green using Leishman stain-doped FeZnS2 are 82, 79 and 89, respectively. [ABSTRACT FROM AUTHOR]

The release of industrial effluents into fresh water is a major contributor of water contamination. Therefore, it is highly desirable to develop a viable solution to this alarming issue to improve the quality of clean water. To enhance the photocatalytic efficiency and hence utilization ratio of CuO, a series of CuO–FeSe2 composites with different varying contents of FeSe2 were prepared through facile synthetic methods. X-ray diffraction (XRD) and energy-dispersive X-rays (EDX) analysis verified that the samples were successfully prepared without any contaminating phases. The average crystallite sizes of CuO and FeSe2 were computed to be 29 and 21 nm respectively. For the CuO–FeSe2 composites, the crystallite sizes varied between 25 and 27 nm. The morphology of CuO was comprised of needle-shaped structures, whereas that of FeSe2 was observed to be flower-shaped structures comprising of irregular crystals. A red shift in the bandgap of CuO–FeSe2 composites was observed with the increase in FeSe2 concentration. The prepared photocatalysts were utilized to evaluate their efficiency under visible light against Rhodamine B (RhB). Among all the prepared composites, CuO–75% FeSe2 revealed a remarkable performance and degraded 96% RhB in 180 min. Rate constants for the degradation of the dye were determined by applying the Langmuir–Hinshelwood model. [ABSTRACT FROM AUTHOR]

Water contamination caused by textile dyes can affect human health, calling for effective treatment method. Here, we report the preparation of MgFe2O4/C composite through hydrothermal method to adsorb three dyes including rhodamine B, methyl orange (MO) and acid yellow 17 (AY) in water. MgFe2O4/C obtained a surface area of 692.32 m2/g and MgFe2O4 particles were well-dispersed on porous carbon matrix. Taguchi experimental design (L16) was conducted to test the effect of four factors, including initial concentration, adsorbent dosage, contact time and pH at different four levels. pH was a first-ranked factor for adsorption of all three dyes with the highest contribution between 33.20 and 55.61%. The highest capacity (158.12 mg/g) was determined for MO dye adsorption under a concentration of 40 mg/L, pH 3, a dose of 0.05 g/L, and a duration of 240 min. The experiments of MgFe2O4/C reusability were performed, reaching at least fourth cycles offering potential for reuse. It is recommended that Taguchi orthogonal array design can be well adopted to reach the best condition of organic dyes adsorption by MgFe2O4/C composite. [ABSTRACT FROM AUTHOR]

Photothermal nanoparticles are recent materials which provide additional capacity supply during the photocatalytic reactions. Iron disulfide (FeS2) nanoparticles with unique chemical and optical properties effectively absorb the full broad spectrum and convert the solar energy into chemical energy owing to its small band gap energy of 1.5 eV. However, the fast electron–hole pair recombination reduces the efficiency of FeS2 and depresses the redox reaction. In this novel research, FeS2/CeO2 heterojunctions are prepared for successful decomposition of rhodamine B dye as toxic pollutant belonging to xanthene dye group. CeO2 nanoparticles are fabricated through sol–gel procedure via triton- × 100 as pore directing agent. Nanoparticle's FeS2 is developed by the precipitating process under a N2-atmospheric condition. Various amounts of FeS2 particles were deposited in ultrasonic bath onto the surface of CeO2. The nanostructures, crystalline and optical properties of the solid specimens are evaluated by scanning and transmission electron microscopy (SEM and TEM) with Energy-dispersive X-ray spectroscopy (EDS), x-ray diffraction (XRD), photoluminescence (PL) and diffuse reflectance spectroscopy (DRS) techniques. The photocatalytic efficiency of CeO2, FeS2 and various compositions of FeS2/CeO2 heterojunction was deliberated via following the decomposition of rhodamine B dye under UV radiation at 365 nm. FeS2 efficiently transfers the absorbability of the nanocomposite to deep visible region by decreasing the band gap energy of CeO2 from 2.3 to 1.5 eV revealing that FeS2 determines the optical properties of the nanocomposites. The charge transportation proceeds through type (I) heterojunction with accumulation of the massive charge carriers in the valence and conduction bands of FeS2 nanoparticles. The novel nanocomposite with strong absorbability of nearly full absorption spectrum could be an effective photocatalyst for decomposition of toxic organic dye from various sources of water. [ABSTRACT FROM AUTHOR]

The results of evaluating the adsorption and fluorescent properties of azolotriazine compounds and phases based on cadmium sulfide quantum dots in vapors of volatile organic compounds (biomarkers of living systems) are considered. The adsorption properties of phases based on organic dyes and encapsulated semiconductors towards vapors of alcohols, ketones, amines, acids, ammonia, and aldehydes are investigated using direct high-sensitivity piezoelectric quartz microweighing. The spectral properties and their variations in analyte vapors are investigated using various spectroscopy methods (absorption, photoluminescence). The research results are compared, and the potential for optimizing this stage is assessed. It is proposed to evaluate the consistency of methods for predicting changes in fluorescent properties in test systems for volatile organic compounds using the Kendall coefficient of concordance, W. The highest level of agreement (W = 0.89) was observed between the methods of spectrofluorimetry and direct vapor microweighing upon adsorption on phases being potential fillers of test systems. A correlation between the results obtained by different fluorescence methods (visual plate test systems and fluorimetry of phases on paper substrates) is 0.80, which confirms a high degree of consistency in assessments using them in the degree of interaction between the analytes and organic, combined fluorochromes. The methods closely related in the nature of the analytical response do not exhibit better agreement than the method of direct vapor microweighing on microphases of fluorimetric reagents of different nature (cadmium sulfide quantum dots/chitosan, organic azolotriazine compounds, mixed phases). This, in turn, enables the selection of simpler, more available, and more rapid methods and means of analysis in routine experiments. [ABSTRACT FROM AUTHOR]

This work demonstrated enhanced adsorption capabilities of lignin nanoparticles (LNPs) synthesized via a straightforward hydrotropic method compared to pristine lignin (PL) powder for removing methylene blue dye from aqueous solutions. Kraft lignin was used as a precursor and p-toluenesulfonic acid as the hydrotrope to produce spherical LNPs with ~ 200 nm diameter. Extensive characterization by SEM, AFM, DLS, zeta potential, and BET verified successful fabrication of microporous LNPs with fourfold higher specific surface area (14.9 m2/g) compared to PL (3.4 m2/g). Significantly reduced particle agglomeration and rearranged surface chemistry (zeta potential of −13.3 mV) arising from the self-assembly of lignin fractions under hydrotropic conditions enabled the application of LNPs and superior adsorbents compared to PL. Batch adsorption experiments exhibited up to 14 times higher methylene blue removal capacity, from 20.74 for PL to 127.91 mg/g for LNPs, and ultrafast equilibrium uptake within 3 min for LNPs compared to 10 min for PL. Kinetic modeling based on pseudo-first-order and pseudo-second-order equations revealed chemisorption as the predominant mechanism, with a rate constant of 0.032825 g/mg·h for LNPs—over an order of magnitude higher than PL (0.07125 g/mg·h). Isotherm modeling indicated Langmuir monolayer adsorption behavior on relatively uniform lignin surface functional groups. The substantially augmented adsorption performance of LNPs arose from the increased surface area and abundance of surface functional groups, providing greater accessibility of chemically active binding sites for rapid dye uptake. Overall, this work demonstrates that tailoring lignin nanoparticle structure and surface chemistry via scalable hydrotropic synthesis is a simple and sustainable approach for producing highly efficient lignin-based nano-adsorbents for organic dye removal from industrial wastewater. [ABSTRACT FROM AUTHOR]

The research article introduces the unexplored synergistic effect of amorphous titanium dioxide and phosphorus-doped carbon nanodot hybrid [C-TiO2(am)] for the ultrafast adsorption of methylene blue and crystal violet dyes. The hybrid eliminates 98% of methylene blue dye (MB) at a concentration of 32 mg/L and 96% of crystal violet dye at a concentration of 62 mg/L from the aqueous solution within 5 min of contact time at ambient temperature. The incorporation of phosphorus-doped carbon nanodot in amorphous TiO2 modifies the oxygen vacancy, which enhances the material's affinity for organic dyes like MB and crystal violet. The significance of defects on the adsorption efficiency of C-TiO2 (am) is obtained and compared with that of amorphous titanium dioxide [TiO2(am)] and the crystalline phase of hybrid (C-TiO2). The dye removal percentages of TiO2 (am) and C-TiO2 are ca.3% and ca.32%, respectively, which is feeble compared to the dye removal percentage of C-TiO2 (am) (ca. 98%). The possible mechanism of organic dye adsorption of C-TiO2 (am) is derived through the detailed discussion of porosity, morphology, functional groups, and chemical compositions. The impact of temperature on dye adsorption and removal rate is determined using non-linear regression analysis. The remarkable characteristic adsorption features of C-TiO2 (am) suggest that it can be considered as a new potential adsorbent for water purification. The remarkable characteristic adsorption features of C-TiO2 (am) suggest that it can be considered as a new potential adsorbent for water purification. [ABSTRACT FROM AUTHOR]

The current study employed the hydrothermal approach to graft chitosan functionalized-SiO2 nanoparticles with an aromatic aldehyde (salicylaldehyde, SA) to obtain an organic–inorganic nanohybrid composite of salicylaldehyde-based chitosan Schiff base/SiO2 (CTS-SA/SiO2) for uptake of an acidic azo dye (acid red 88, AR88) from aqueous media. The effects of A: CTS-SA/SiO2 dose (0.02–0.1 g), B: pH (4–10), and C: time (10–90 min) on the adsorption performance of CTS-SA/SiO2 towards AR88 were studied systematically by the Box–Behnken Design (BBD). The CTS-SA/SiO2 dosage, pH, and contact time resulted in maximum dye elimination (76.46%) of AR88, according to the results of the BBD model. These variables were 0.093 g of CTS-SA/SiO2, pH 4.5, and 87.4 min. The pseudo-second order and Langmuir isotherm provide an account of the experimental results for AR88 adsorption by CTS-SA/SiO2. The calculated maximum Langmuir adsorption capacity for CTS-SA/SiO2 is equal to 184.2 mg/g. The high adsorption of AR88 onto the CTS-SA/SiO2 can be mainly ascribed to electrostatic forces between the protonated CTS-SA/SiO2 and the AR88 anions, along with n–π, π–π, and H-bond interactions. This research demonstrates that CTS-SA/SiO2 has promising potential as an adsorbent for organic dye removal from water systems. [ABSTRACT FROM AUTHOR]

A highly flexible and cost-effective copper tape decorated with silver nanoparticles (Cu-TAg) has been developed for surface-enhanced Raman spectroscopy (SERS) sensing of multi-hazardous environmental pollutants. Highly ordered and spherical-shaped silver nanoarrays have been fabricated using a low-cost thermal evaporation method. The structural, morphological, and optical properties of Cu-TAg sensors have been studied and correlated to the corresponding SERS performances. The size of nanoparticles has been successively tuned by varying the deposition time from 5 to 25 s. The nanoparticle sizes were enhanced with an increase in the evaporation time. SERS investigations have revealed that the sensing potential is subsequently improved with an increase in deposition time up to 10 s and then deteriorates with further increase in Ag deposition. The highest SERS activity was acquired for an optimum size of ~ 37 nm; further simulation studies confirmed this observation. Moreover, Cu-TAg sensors exhibited high sensitivity, reproducibility, and recycling characteristics to be used as excellent chemo-sensors. The lower detection limit estimation revealed that it can sense even in the pico-molar range for sensing of rhodamine 6G and methylene blue. The estimated enhancement factor of the sensor is found to be 9.4 × 107. Molecular-specific sensing of a wide range of pollutants such as rhodamine 6G, alizarin red, methylene blue, butylated hydroxy anisole, and penicillin–streptomycin is demonstrated with high efficiencies for micromolar spiked samples. Copper tape functionalized with Ag arrays thus demonstrated to be a promising candidate for low-cost and reusable chemo-sensors for environmental remediation applications. [ABSTRACT FROM AUTHOR]

Industrial wastewater has detrimental impacts on aquatic ecosystems and the environment. Among the significant contributors to water pollution are organic dyes, which are frequently released into untreated outflow water. Hence, effective degradation of these dyes and their derivatives using heterogeneous photocatalysts is imperative before discharge. In this study, we successfully synthesized a novel nanocomposite by g-C3N4 coupled with TiO2 and decorated it with Ni followed by cost-effective methods. Immaculate g-C3N4 coupled with TiO2 (TiO2+) and modified with nickel (Ni+) was synthesized through melamine calcination followed by hydrothermal processing. Characterization through diverse electro-analytical techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and Brunauer-Emmett-Teller (BET), was conducted on the novel photocatalysts. XRD results revealed their high crystallinity, enhanced through modification. The effectiveness of these photocatalysts in degrading the organic dye methylene blue (MB) under UV–Vis light was thoroughly investigated. It also investigated how the results were affected by important factors involving contact time, dye and photocatalyst dosages, pH, and reusability. Among the photocatalysts, the composite g-C3N4-TiO2s, decorated with Ni, exhibited exceptional performance, displaying substantial degradation efficacy. The findings demonstrate that the novel g-C3N4-based photocatalysts are highly efficient at degrading organic dyes, so the work is expected to be the best contribution in the photodegradation study of organic contaminants. [ABSTRACT FROM AUTHOR]

Today, nanoscience explores the potential of nanoparticles due to their extraordinary properties compared to bulk materials. The synthesis of metal nanoparticles using plant extracts is a very promising method for environmental remediation, which gets global attention due to pollution-led global warming. In the present study, iron nanoparticles (FeNPs) were successfully synthesized by the green method using Vernonia amygdalina plant leaf extract as a natural reducing and capping agent. Biosynthesized FeNPs were characterized with different analytical techniques such as UV–visible, FT-IR, XRD, and SEM. The analysis revealed the formation of amorphous FeNPs with an irregular morphology and non-uniform distribution in size and shape. The average particle size was approximately 2.31 µm. According to the catalytic degradation investigation, the FeNPs produced via the green approach are highly effective in breaking down both CV and MB into non-toxic products, with a maximum degradation efficiency of 97.47% and 94.22%, respectively, when the right conditions are met. The kinetics study exhibited a high correlation coefficient close to unity (0.999) and (0.995) for the degradation of MB and CV, respectively, for the zero-order pseudo-kinetics model, which describes the model as highly suitable for the degradation of both dyes by FeNPs compared to other models. The reusability and stability of biosynthesized nano-catalysts were studied and successfully used as efficient catalysts with a slight decrease in the degradation rate more than four times. The results from this study illustrate that green synthesized FeNPs offer a cost-effective, environmentally friendly, and efficient means for the catalytic degradation of organic dyes. [ABSTRACT FROM AUTHOR]

In this work, a composite ZnO/MoS2/AuNPs supported on carbon fiber cloth (CFC) was prepared by progressively growing ZnO nanorods array, MoS2 nanosheets and AuNPs on CFC for sensitive SERS detection and efficient photocatalytic degradation of organic dye pollutants. The ZnO/MoS2 heterojunctions showed a significant CM effect and further decorating AuNPs with EM effect improved the detection limit of crystal violet (CV) from 10–6 to 10–13 M. The composite can be used for qualitative SERS detection of CV or Nile blue in standard solution or real samples with high stability and good stability. The enhancement mechanisms of CFC/ZnO/MoS2 and CFC/ZnO/MoS2/AuNPs were discussed based on corresponding characterizations and calculations. The composite also showed efficient photocatalysis for dye degradation. The ZnO/MoS2 heterojunction played a key role in enhancing the charge separation rate and improving the photocatalytic performance. The materials achieved degradation efficiencies of 71.4% for CV (1.5 × 10–5 M) after 60 min irradiation under visible light. The active radical species were investigated and possible degradation approach were proposed. Such composite with both SERS enhancement and visible light photodegradation ability has great promise in environment monitoring and remediation. [ABSTRACT FROM AUTHOR]

Herein, core–shell magnetic nanoparticles are modified with imidazolium-tagged phosphine and propylene glycol moieties and used for the stabilization of bimetallic AuCu nanoparticles. The structure and morphology of the prepared material are identified with SEM, TEM, XRD, XPS, atomic absorption spectroscopy, Fourier translation infrared spectroscopy, and a vibrating sample magnetometer. This hydrophilic magnetic bimetallic catalyst is applied in the reduction of toxic nitroarenes and reductive degradation of hazardous organic dyes such as methyl orange (MO), methyl red (MR), and rhodamine B (RhB), as well as in the degradation of tetracycline (TC). This magnetic AuCu catalyst indicated superior activity in all three mentioned reactions in comparison with its single metal Au and Cu analogs. This catalyst is recycled for 17 consecutive runs in the reduction of 4-nitrophenol to 4-aminophenol without a significant decrease in catalytic activity and recycled catalyst is characterized. [ABSTRACT FROM AUTHOR]

Recent progress in the development of MnO2-based micromotors has shown the immense potential of these motile devices to remediate environmental contamination. However, the production of such micromotors on an industrial scale through a facile, efficient and reproducible process remains challenging. The present work aimed to address this issue using naturally occurring and abundant pine pollen (PP) grains. The immersion of PP in potassium permanganate (KMnO4) solutions was found to generate MnO2 nanoparticles (NPs) on the PP surfaces, the amount and distribution of which was readily adjusted by varying the coating time. Because of the asymmetrical shape of the PP grains, the MnO2/PP composites exhibited rapid self-propulsion at a maximum speed of 360.686 μm/s (approximately eight body lengths/s) in low-concentration hydrogen peroxide (H2O2) solutions. The ability of these materials to remediate heavy metal pollutants was also examined and was evidently increased by a factor of 1.5 compared with static counterparts. These composites could also be recovered and reused over three consecutive cycles. The competitive cost, continuous motion and superior decontamination capacity of these materials suggests potential applications in the rapid removal or degradation of heavy metal ions, toxic organic dyes, pathogenic bacteria and other pollutants in wastewater. These micromotors represent a new approach to the utilization of natural materials in environmental remediation. [ABSTRACT FROM AUTHOR]

Functionalized conjugated microporous polymers (CMPs) containing amino, imino, and hydrazine groups are synthesized by the Sonogashira–Hagihara coupling reaction. Notably, the porosities, thermal stabilities, and morphologies of the CMPs can be controlled by the introduction of functional groups. Here, the relationships between the functional groups and photocatalytic performance are discussed for the first time. The CMP nanowires exhibit excellent photocatalytic performance in organic pollutant degradation: the degradation rate obtained by CMP-I3 bearing naphthalene groups via an imine bond is > 99.99%, and ~ 99.71% of the degradation activity is maintained after five cycles. Notably, the excellent photocatalytic properties of CMP-I3 are imparted by the introduction of the naphthalene groups, which reduced the band gap. The improved charge-transfer activity accounts for the highest and lowest photocurrent intensity and resistance achieved, respectively. Furthermore, the photocatalytic mechanism of CMPs reveals that the superoxide anion is the main active substance in the photocatalytic degradation of dyes. [ABSTRACT FROM AUTHOR]

The effect of plasmonic nanoparticles (NPs) on the fluorescence and phosphorescence intensity of organic dye molecules was studied theoretically and experimentally. A theoretical model that takes into account nonradiative transfer of excitation energy from a molecule to an NP and the changes in the rates of spontaneous emission and light absorption by a molecule near an NP was proposed to calculate the luminescence intensity of a molecule in the presence of a plasmonic NP. Numerical estimates for an erythrosine molecule and a silver NP showed that the greatest increase in luminescence was observed at distances of 4–8 nm between the molecule and the NP surface. Experimentally observed changes in luminescence spectra and shortening of the erythrosine triplet state lifetime in poly(vinyl alcohol) films doped with silver NPs were explained using the proposed model. [ABSTRACT FROM AUTHOR]

Photocatalysis promotes eco-friendly reactions under mild conditions, and among photocatalytic agents are dyes, which have good redox potential in their excited states. The aim of the current contribution was to design a novel series of coumarins based on DFT analysis of their photochemical properties. The coumarin amide group serves as a linking group to cinnamic acid, allowing for electron delocalization throughout the system and the stabilization of the anionic and cationic species. An electronic structure analysis was performed by calculating vertical excitations and emissions, obtaining conceptual DFT chemical descriptors and nonlinear optical parameters (e.g., first static hyperpolarizability β). The novel coumarin derivatives display a reduction in the HOMO–LUMO energy gap from 6.11 to 4.2 eV, large oscillator strength (1.93), efficient nonlinear optical behavior, and excellent redox potential. Hence, they are promising compounds for photocatalytic activity. The present work shows a series of computational parameters that can be considered for the design of a molecule with potential photocatalytic activity, evaluating in this instance a series of new coumarins, promising from the computational point of view [ABSTRACT FROM AUTHOR]

Context: A series of five organic dyes (Mi, i = 1–5) of the D-A'-π-A structure were designed based on reference dye (Ref), and the influence of different auxiliary acceptors (A') on their efficiency in dye-sensitized solar cells (DSSC). Methods: Was studied theoretically using density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. In this context, the electronic structures, optical properties, and the parameters influencing the power conversion efficiency (PCE), such as light harvesting efficiency (LHE), electron injection driving force (∆Ginject.), and open circuit photo-voltage (VOC), have been evaluated and discussed. The modification of the auxiliary acceptor (A') in the D-A'-π-A structure of the designed organic dyes has the advantage of significantly decreasing the band gap, which leads to the broadening of the absorption band that is red-shifted and improves the photovoltaic characteristics compared to Ref. Theoretical results reveal that M1, and M5 can be used as excellent sensitizer candidates for DSSC applications. [ABSTRACT FROM AUTHOR]

Environmental contamination is a major global concern. Organic dyes pose a significant threat as water pollutants, leading to the depletion of natural resources. Molybdenum disulfide (MoS2), a type of two-dimensional transition metal dichalcogenide, has gained considerable attention due to its impressive properties, such as stability, surface area, and tunable interlayer spacing. It has emerged as a promising material for both photocatalytic degradation and adsorption of harmful organic dyes. This article provides an overview of recent advancements in MoS2-based nanomaterials for the removal of organic dyes from solutions through adsorption and photocatalytic processes. The review delves into the fundamental properties of MoS2, explores various synthesis methods, and various modifications of the material to enhance its dye removal efficiency, and addresses potential challenges associated with its application in this field. Furthermore, the article discusses the prospects for improving MoS2-based materials for enhanced adsorption and photocatalytic degradation of organic dyes. [ABSTRACT FROM AUTHOR]

The new design of 6,6′-di(thiophen-2-yl)-4,4′-bipyrimidine (DTB)-based organic dyes (TCIT1-TCIT6) for dye-sensitized solar cell (DSSC) application was systematically designed by a donor (D), π-linker, and acceptor (A) design to form the D-π-D-π-A structure. The exchange–correlation (XC) as well as long-range corrected (LC) functionals were utilized to represent these dyes in density functional theory (DFT) and time-dependent DFT (TD-DFT) techniques. The TD-CAM-B3LYP approach was perfectly matched the DTB dye. Energy gaps between highest occupied molecular orbitals (HOMOs) and lowest unoccupied molecular orbitals (LUMOs) ranged between 1.73-2.92 eV. Their light-harvesting efficiency (LHE) values ranged between 0.001-0.106 eV with dye TCIT5 with the highest value. The open circuit voltage calculated against the DTB as donor moiety ranged 2.45–3.64 eV with positive values to demonstrate their ON position in their solar devices. All the dyes showed a very short excited-state lifetime ranging between 0.0001-0.0051 ns which showed how easily they can shift from an excited- (fluorescent) to ground-state position. Improved results for DSSCs were provided by the intended dyes in addition to their high horizontal dipole moment (µnormal) and open circuit photovoltage (eVOC). It benefits increased efficiency as a result. The findings of the current theoretical analysis show that all D-π-D-π-A dyes may be suitable sensitizers for DSSC applicability. [ABSTRACT FROM AUTHOR]

In the present study, the synthesis of metal organic framework (MOF) template-derived materials is reported. Cubic Fe2O3·TiO2 material was synthesized by using Prussian blue as the sacrificed template and aqueous soluble TiOSO4 as a TiO2 precursor. The obtained material was characterized by Fourier transform infrared (FT-IR) and Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet visible diffuse reflectance spectroscopy (UV-Vis DRS), and nitrogen adsorption/desorption isotherms. The characterization confirmed the existence of cubic α-Fe2O3 core and anatase TiO2 shell in the composite. Furthermore, the appearance of TiO2 shell has significantly enhanced the Brunauer–Emmett–Teller (BET) surface area yet still retained small bandgap energy of around 2.0 eV. This material was employed to degrade chosen organic dyes, including cationic dyes and anionic dye, in a heterogeneous photo-Fenton like system. The experimental results showed that this material exhibited higher adsorption and degradation capacity toward cationic dyes than anionic dye. The fitting of experimental data into two kinetic models revealed that the removal of the dyes can be better described by Langmuir-Hinshelwood model. The recyclability of the catalyst was also examined. [ABSTRACT FROM AUTHOR]

In this paper, coal gangue, a solid waste is used as raw material to provide silicon and aluminum sources for synthesis of zeolite. A coal gangue zeolite based Cu/Fe–X catalyst is successfully prepared by immersion-calcination method, which is used to remove Rhodamine B from aqueous solution. The characterization results show that Cu and Fe have been successfully loaded on zeolite, not damaged its structure, and these nanoparticles are highly dispersed and low crystallinity. This special structure will enhance its catalytic ability to activate H2O2. The experiment showed that hydroxyl radical (·OH) was the main active species for catalytic degradation of Rhodamine B, and the circulation of Cu2+ to Cu1+ and Fe3+ to Fe2+ could synergistically produce ·OH. Furthermore, the redox potential of Cu1+ and Cu2+ is lower than Fe2+ and Fe3+, which can promote Fe3+ circulate to Fe2+, further promote Fe2+ to activate H2O2 to decompose into ·OH, and overcome the speed limiting step of Fenton-Like catalytic reaction. The Cu/Fe–X catalyst can activate H2O2 in wide pH range (1–10). Under optimal conditions, the catalytic degradation rate can reach 99.9%, and the TOC removal rate is as high as 98.5%. Therefore, Cu/Fe–X/H2O2 system can effectively remove organic dyes, and has a high industrial application prospect. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman spectroscopy (SERS) is a highly sensitive and reliable fingerprinting technique. However, its analytical capability is closely related to the quality of a SERS substrate used for the analysis. In particular, conventional colloidal substrates possess disadvantages in terms of controllability, stability, and reproducibility, which limit their application. In order to address these issues, a simple, cost-effective, and efficient SERS substrate based on silver nanoparticle arrays (Ag NPAs) and sandpaper-molded polydimethylsiloxane (SMP) was proposed in this work. Successfully prepared via template lithography and liquid–liquid interface self-assembly (LLISA), the substrate can be applied to the specific detection of organic dyes in the environment. The substrate exhibited good SERS performance, and the limit of detection (LOD) of rhodamine 6G (R6G) was shown to be 10−7 M under the optimal conditions (1000 grit sandpaper) with a relative standard deviation (RSD) of 7.76%. Moreover, the SERS signal intensity was maintained at 60% of the initial intensity after the substrate was stored for 30 days. In addition, the Ag NPAs/SMP SERS substrate was also employed to detect crystal violet (CV) and methylene blue (MB) with the LODs of 10−6 M and 10−7 M, respectively. In summary, the Ag NPAs/SMP SERS substrate prepared in this study has great potential for the detection of organic dyes in ecological environments. [ABSTRACT FROM AUTHOR]

Context: This research aims to investigate the potential of pyrazine-based small donor moieties as donor–acceptor switches for optical and photovoltaic applications. The designed organic dyes have a high light harvesting efficiency (LHE) and can potentially generate significant electrical energy. Methods: The study focuses on understanding the structural and electronic properties of these dyes through the analysis of dihedral angles, bond lengths, and energies of frontier molecular orbitals The UV–Vis spectroscopy parameters of the designed organic dyes revealed their absorption characteristics, including transition energies, wavelengths (λmax), and oscillator strengths (f). The photovoltaic properties of the developed organic dyes show a range of values: a range of 0.95–0.99 for LHE and a range of 1.77–33.02 W for maximum power output (Pmax) with the highest value for dye DDP5. For their stabilization energies, their natural bond orbitals had values ranging from 0.56 to 128.48 kcal/mol, their E(j)E(i) values from 0.22 to 1.29 a.u, and their Fi,j values from 0.024 to 0.213 kcal/mol. Out of all dyes, the DDP5 produced highest push–pull effect and can be good choice for further studies. The design of these novel organic materials for effective and economical solar energy conversion will be aided by evaluating the potential of 5,10-diphenyl-5,10-dihydrophenazine as a donor moiety and determining the structure–property correlations controlling the photovoltaic performance of the compounds. [ABSTRACT FROM AUTHOR]

In this study, the Fe3O4/rGO/Ag magnetic nanocomposite was synthesized and employed as an adsorbent for the removal of tetracycline (TC), crystal violet (CV), and methylene blue (MB) from water samples. The influential parameters in the removal process were identified and optimized using response surface methodology (RSM). Characterization of the product was performed through field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDX), vibrating-sample magnetometer (VSM), and X-ray diffraction (XRD) analysis. XRD and SEM analysis revealed the successful synthesis of the Fe3O4/rGO/Ag nanocomposite. EDX analysis elucidated the accuracy and clarity of the chemical composition of the magnetic nanocomposite structure. Additionally, the separation of the nano-adsorbent from the solution can be achieved using a magnetic field. Maximum removal of analytes was obtained at pH of 6, amount of nanocomposite 0.014 g, ultrasonic time of 8 min and concentration of 21 mg L−1. Under optimal conditions, the removal efficiencies for TC, CV, and MB were 91.33, 95.82, and 98.19%, respectively. Also, it was observed that after each adsorption–desorption cycle, Fe3O4/rGO/Ag magnetic nanocomposite had good stability to remove TC, CV, and MB. Achieving nearly 98% removal efficiency in optimal conditions showed that Fe3O4/rGO/Ag magnetic nanocomposite is an effective adsorbent for removing TC, CV, and MB from wastewater samples. [ABSTRACT FROM AUTHOR]

Photocatalysis is an innovative method for environmentally friendly wastewater treatment. A development of modern photocatalyst, which is suitable for industrial water purification from hazardous organic compounds, is a global challenging problem. Novelty of this work is in the development of synthetic approach based on hydrothermal treatment in a combination with computational experiment. Oriented attachment mechanism was engaged via hydrothermal treatment to produce SnO2 nanoparticles out of preliminary obtained initial blocks – smaller SnO2 nanoparticles, obtained via precipitation method. The initial blocks and obtained nanoparticles were studied with a large set of methods, such as XRD, FTIR, SSA, HRTEM, XPS, and Raman spectroscopy. The oriented attachment mechanism was studied using a computational method, based on the earlier developed approach, revealing the role of ions, existing in the reaction media, and the path of nanoparticle formation. Initial blocks and obtained nanoparticles were tested as photocatalysts on test solutions of organic dyes (methylene blue, rhodamine 6G and congo red). The more complex the dye structure, the more difficult is photocatalytic decomposition of its molecule. However, optimization of the extraction procedure allowed to achieve up to 90% extraction efficiency. [ABSTRACT FROM AUTHOR]

Dye pollution resulting from the discharge of untreated wastewater has become a major environmental concern. In this study, we propose a green and cost-effective approach for the photocatalytic degradation of dye pollutants using a nanocomposite (NC) of manganese oxide (Mn3O4) modified with polyvinylpyrrolidone (PVP). The Mn3O4 nanoparticles (NPs) were synthesized through a green method using a biogenic extract of Pistacia lentiscus leaves. The resulting Mn3O4 NPs were then modified with PVP, a non-ionic polymer, to enhance their stability and catalytic performance. The synthesized Mn3O4/PVP NC was characterized using various analytical techniques, including Fourier transform infrared spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy. The findings showed that the Mn3O4 NPs and Mn3O4/PPV NC exhibit spherical morphology with an average size of 37 nm and 45 nm, respectively. The Mn3O4 NPs and Mn3O4/PVP NC exhibited optical bandgap energies of 1.8 eV and 1 eV, indicating the effective use of these NPs as photocatalysts. The nanocomposite exhibited exceptional catalytic performance in degrading bromophenol blue (BPB) and ortho-toluidine blue (O-TB), achieving degradation rates of 98% and 95% within 75 minutes. In comparison, Mn3O4 NPs showed lower efficiencies with approximately 14% degradation for BPB and 6% for O-TB. Optimal conditions for dye degradation and subsequent cycles were determined, and first-principles calculations revealed insight into the adsorption energy between the dyes and the Mn3O4/PVP surface. This study highlights the potential of Mn3O4/PVP nanocomposite as an effective and eco-friendly catalyst for dye pollutant degradation, offering a promising solution for wastewater treatment across industries. [ABSTRACT FROM AUTHOR]

In this study, a heterogeneous metal–organic framework catalyst was meticulously prepared and extensively employed for the reduction of nitroarenes, congo red, and methylene blue. The catalyst was synthesized using a straightforward method, resulting in the formation of nanorods with well-defined morphology. These nanorods, composed of nanorod-hydroxyapatite, served as an exceptional and heterogeneous support for the fabrication of a metal–organic framework composite. In the following, surface functionalization was carried out using asparagine and TAZ-IMI, which was prepared by combining imidazole and cyanuric chloride. To enhance the catalytic performance, Pd(OAc)2 was immobilized onto the composite, leading to the formation of a novel n-HA@SiO2–ASP–Pd–TAZ–IMI catalyst. Extensive characterization studies were conducted to confirm the successful formation and structural integrity of the catalyst. The n-HA@SiO2–ASP–Pd–TAZ–IMI catalyst exhibited remarkable catalytic activity in the reduction of nitro compounds, utilizing NaBH4 as the reducing agent, resulting in excellent yields. Notably, the catalyst demonstrated excellent recyclability, as it could be easily reused up to three times with only a slight decrease in reaction yield. [ABSTRACT FROM AUTHOR]

Water pollution has become a major environmental threat owing to the expeditious development of industries. These industries rapidly release wastewater containing harmful dyes (organic pollutants), which significantly affect the lives of humans and aquatic organisms to a huge extent. Therefore, the elimination of the pollutants in the contaminated water has become the primary need of the moment that is to be treated before it discharges into the environment. This article mainly focuses on the adsorption mechanism of the organic dye methylene blue from wastewater under sunlight using a zinc-metal organic framework (Zn-MOF). The Zn-MOF, being a three-dimensional porous structure was synthesized by the direct precipitation method using zinc metal ions and terephthalic acid (or) benzene-1,4-dicarboxylic acid as a connecting linker. Then, morphological and optical characterizations, along with the analysis of thermal and surface parameters, were performed for the synthesized Zn-MOF. The synthesized Zn-MOF appeared to be in a cubic form with a pore volume of about 0.006 cc/g. It was also found to have a surface area of 4.705 m2/g, with an absorbance range of 239.39 nm. The elemental composition of zinc in the synthesized Zn-MOF was approximately 25.41%, proving that the synthesized MOF is a Zinc-based MOF. As the results showed many properties related to the adsorption mechanism, Zn-MOF was chosen to proceed with the adsorptive application of removing the methylene blue dye from wastewater under sunlight. This application provides an efficient solution for the treatment of wastewater through the adsorption property of Zn-MOF, thereby proving its potential as an adsorbent. [ABSTRACT FROM AUTHOR]

In the present study, a greener method has been developed for the synthesis of ZnO nanoparticles using the aqueous leaf extract of Elaeocarpus Sylvestris. The as-synthesized Elaeocarpus Sylvestris-coated ZnO nanoparticles (ESZnO NPs) were characterized using various spectroscopic and microscopic techniques. The average size of the ESZnO NPs was 81 nm based on TEM analysis. FTIR spectra revealed that Elaeocarpus Sylvestris leaf extract contains phenolic compounds, and accordingly, a plausible mechanism for the formation of ZnO NPs was proposed. The prepared ESZnO NPs exhibited efficient photocatalytic activity for the removal of methyl orange (MO) and methylene blue (MB) organic dye pollutants. The photocatalytic degradation of MO and MB followed pseudo first order kinetics with rate constants of 0.00265 min−1 and 0.01034 min−1, respectively. The antimicrobial activity of the ESZnO NPs was evaluated against both gram-positive bacteria (Enterococcus faecalis) and gram-negative bacteria (Pseudomonas aeruginosa) employing the agar-well diffusion method. ESZnO NPs have shown promising antimicrobial activity. The current study shows a newer path for synthesizing ZnO NPs with a wide range of applications. [ABSTRACT FROM AUTHOR]

Context: In this work, we designed ten new organic phenothiazine dyes bridged by different πi-spacers (PTZ1-PTZ10) of D-π-A type based on the synthesized dye CC202-III for their efficacy in dye-sensitized solar cells (DSSC) applications. To learn how various π-spacers affect their performance in DSSCs, these isolated dyes and dye-cluster systems have had their geometries, electronic structures, absorption spectra, dipole moments, and molecular electrostatic potential examined and talked about. Additionally, a number of quantization parameters that affect power conversion efficiency (PCE), including light collection efficiency (LHE), reorganization energy (λtotal), vertical dipole moment (μnormal), strength electron injection driving force (ΔGinject), regeneration driving force (ΔGreg), excited state lifetime (τ), and open circuit voltage (VOC), were calculated in order to identify the organic dyes that would be best suited for DSSC applications. Calculated results revealed that the designed dyes PTZ3, PTZ4, PTZ5, and PTZ10 exhibit a lower energy gap among all dyes compared to the corresponding CC202-III. Additionally, PTZ3, PTZ4, PTZ5, PTZ7, PTZ8, PTZ9, and PTZ10 exhibit significant red-shifted absorption spectra compared to the other dyes with a larger oscillator strength, which improves the photocurrent density of the devices. The findings thus imply that bridge modification is a workable tactic to raise DSSC effectiveness. Method: We used density functional theory (DFT) and time-dependent DFT (TD-DFT) methods to study the electronic and photovoltaic properties of the dyes designed (PTZ1–PTZ10) to assess their effectiveness in DSSCs. DFT and TD-DFT simulations are theoretically used to deeply analyze key characteristics of all organic dyes that affect open-circuit voltage (VOC) and short-circuit current (JSC) to identify structure–property relationships. [ABSTRACT FROM AUTHOR]

Light–matter interaction leads to excitation of molecules, which, in turn, can exchange energy with a localized electromagnetic field. This can be used for engineering of the electronic and vibrational energy levels of the molecules. This study considers the conditions for the emergence of the strong light–matter coupling regime for organic dye molecules in a tunable Fabry–Perot microcavity formed by a convex mirror and a flat reflecting surface. The sample studied was made of hexagonal boron nitride (hBN), polyvinylpyrrolidone polymer (PVP, 55 kDa), and rhodamine 6G fluorophore (R6G). Strong light–matter coupling was obtained in a sample with a low concentration of PVP. Adjustment of the optical path length in the microcavity by varying the thickness of the hBN–R6G–PVP film made it possible to obtain a high density of modes in the cavity (several tens of (λ/n)3) and, hence, to study the weak and strong light–matter coupling regimes. The results offer the possibility of studying the basic mechanisms of resonant light–matter interaction at room temperature, as well as developing new practical applications of the strong coupling effect. [ABSTRACT FROM AUTHOR]

Nanosized NiFe2O4 has been obtained using solution combustion synthesis (SCS). The predominant fraction of the particles has a size of 21–50 nm (TEM). The degree of degradation of 2,4-dinitrophenol in a Fenton-like reaction in the absence of the NiFe2O4 catalyst is 6%, and that in the presence of NiFe2O4 is 53%. Effective oxidative degradation of the pollutant was carried out in a less acidic medium and at a higher initial concentration of dinitrophenol in comparison with the classical Fenton process. The results of the study can be applied in the development of new environmentally friendly water treatment systems at enterprises that use organic dyes in production cycles. [ABSTRACT FROM AUTHOR]

New organic dyes (H1-H6) for their promising applications as dye sensitized solar cell (DSSCs) were theoretically designed from 6,6′-di(thiophen-2-yl)-4,4′-bipyrimidine (TB) moiety in acceptor (A), π-spacer, and donor (D) type architecture to create A-π-D-π-D-π-A framework. After their benchmarking study against various exchange correlation (XC) and long-range corrected (LC) functional, the CAM-B3LYP produced accurate results so as selected for further density functional theory (DFT) and time dependent DFT (TD-DFT) studies. The frontier molecular orbitals (FMOs) were analyzed for their electron transfer properties, and their energies of the highest occupied molecular orbital (EHOMO) and the lowest unoccupied molecular orbital (ELUMO) were used to assess various electronic properties. Their energy differences (EH-L) ranged between 1.69 and 2.03 eV indicating their good responsiveness to electron injection (Ginj) being the values greater than 0.2 eV. The maximum absorbance of the dyes was reported around the 388–406 nm while their starting material (TB) had this value to be 371 nm. This redshift was significant with an intensification of electron-withdrawing groups on the dye structures. The dyes were evaluated for their device related parameters like their light harvesting efficiency, open circuit voltage, exciton binding energies, and exciton life times which were found in their promising values. The dyes were analyzed for their linear (α), first (βtotal), and second (γtotal) order nonlinear responses and were found to have significantly higher responses, not only against their starting materials but also those reported in literature for standard molecules (urea and p-nitric acid). Among the dyes under study, dye H4 exhibits the highest molecular polarizability (α) and hyperpolarizability (β and γ) values thanks to two CN substituted units on each ends. These dyes are most likely to have possible optical and photonic uses. Also, according to the results of the current theoretical research, all of these dyes may function as effective photosensitizer for their DSSC application. [ABSTRACT FROM AUTHOR]

Photocatalysts have gained much attention because of the water pollution instigated by the rapid usage of organic dyes for industrial needs. The degradation of these dyes using photocatalysts under natural light is an economical and popular method for water treatment. There is a need to synthesize photocatalytic materials which can generate reactive oxygen species under natural light. Hence, keeping in mind the above point, rose flower-shaped CuS nanostructures have been synthesized first time by solvothermal technique by varying reaction duration. The self-assembled powder of CuS nanostructures is characterized using XRD, FE-SEM, TEM, DLS, EDS, XPS, Raman, FT-IR, and UV–visible spectroscopy. The XRD and TEM analyses confirmed the formation of a polycrystalline hexagonal structure with prominent diffraction peaks. FE-SEM study shows the formation of uniformly self-assembled rose flower-shaped nanostructures of size 2–3 μm composed of densely packed nanoparticles. XPS study shows the presence of Cu(II) and Cu(I) states of copper in the synthesized batch and stoichiometric composition Cu:S is found to be 60:40 at.%. The optical studies showed broad absorption spectra of CuS nanostructures in about 300–800 nm wavelength range. Besides, this work studies the degradation activity of methylene blue and crystal violet organic dyes under natural sunlight conditions without the presence of any additive agent. [ABSTRACT FROM AUTHOR]

We here report the synthesis, characterization, and catalytic performance of new supported Pd(0) catalysts. The catalysts were characterized by SEM, TEM, XRD, FT-IR, VSM, XPS, TG and AAS. The results showed that the catalyst exhibited good catalytic activity in the reaction of degradation of 4-NP and organic dyes MO and MB in water with NaBH4 and amino borane (AB) as the hydrogen sources. At the same time, the catalyst has good recoverability and is easily recovered and recycled from the reaction mixture by applying an external magnet and reusing it in five cycles without significant loss in activity. In the present work, our deliberately designed experiments demonstrate that Ni@Pd immobilized on the surface of hollow Fe3O4@PPy-Gly (HFPG) under mild condition. It exhibits high activity for the reduction of 4-NP and organic dyes by NaBH4 and AB. [ABSTRACT FROM AUTHOR]

Herein, new efficient photocatalysts composed of Cu doped NiS/ZnS quantum dots-composites were synthesized by coprecipitation technique for treatment of organic dyes. Treatment of dyeing-wastewater is an important issue to reduce the environmental pollution and providing a large quantity of pure water. The transmission electron microscope images of pure and Cu doped NiS/ZnS composites show quantum dots particles with size of 3–4 nm. The X-ray diffraction confirmed the formation of cubic ZnS and rhombohedral NiS. Optically, doping by 4 wt% Cu ions was reduced the band gap energy of ZnS from 3.4 to 2.98 eV, which improve the visible light absorption. 4 wt% Cu doped NiS/ZnS nanocomposite reveals a fast and remarkable photodegradation efficiency of 95%, 98% and 97% towards 20 ppm methyl green, methylene blue and Congo red during 60 min of sunlight irradiation. For three cycles, 4 wt% Cu doped NiS/ZnS nanocomposite exhibits significant photodegradation activities of 98%, 92% and 85%, respectively. The improvements of the photocatalytic activity of Cu doped NiS/ZnS nanocomposite can be attributed to some factors including visible-light absorption and charge carriers separation. The Cu doping improves the visible light response of ZnS through reducing the band gap which reinforce the number of the excited electron-hole pairs. Too, Cu ions act as trapping centers (Cu2+ + e → Cu+) which boost the separation of the excited electron-hole pairs and consequently improve the photodegradation activity. This study point out that the integration of p-n heterostructure and doping strategies are efficient for deign of photocatalysts for wastewater treatment. [ABSTRACT FROM AUTHOR]

Context: Dye-sensitized solar cells (DSSCs) have displayed huge potential in inexpensive, efficient, and clean solar energy technology. In this work, seven new dyes with the structure D-A'-A were designed in which the thiophene in the reference dye was replaced by auxiliary acceptors (A'). These dyes consist mainly of a pyranylidene-based electron donor D and the cyanoacrylic acid moiety as acceptor A. A computational investigation was carried out on the effect of various auxiliary acceptors A' on the efficiency of D-A'-A dyes in isolation and after binding to the semiconductor TiO2. Optimized structures, geometrical, optoelectronic, and photovoltaic parameters were calculated to predict promising dyes for potential use as solar cell sensitizers, including band gap (Egap), natural bond orbital (NBO) analysis, nonlinear optical properties (NLO), UV–Vis absorption spectra, maximum absorption wavelength (λmax), reorganization energy (λtotal), light-harvesting efficiency (LHE), electron injection driving force (ΔGinject) and open-circuit photovoltage (VOC). The results of this study revealed that all designed dyes, compared to the reference dye, are characterized by small Egap and λtotal values as well as large λmax, in addition to significant NLO properties and large adsorption energy (Eads). Therefore, all studied dyes can be used as sensitizers in DSSC. Methods: Using Density Functional Theory (DFT) approaches with the B3LYP functional and the 6-31G(d,p) basis set, all ground state geometries of the isolated dyes were fully optimized. Time-Dependent Density Functional Theory (TD-DFT) method using the CAM-B3LYP/6-31G(d,p)/IEF-PCM level was applied to simulate the UV–visible absorption properties. All isolated dye calculations were performed using the Gaussian 09 software package. DFT calculations have been carried out with the DMol3 package included in Materials Studio for simulating the adsorption of the investigated dyestuff on the TiO2 surface of anatase (101), using the generalized gradient corrected approximation (GGA) approach of the Perdew-Burke-Ernzerhof (PBE) functional with the basic set of digital double polarisation (DNP). To study the optical performance of dye@TiO2 the PBE/DNP method present in DMol3 was applied. [ABSTRACT FROM AUTHOR]

A novel, magnetic HKUST-1 MOF based on MgFe2O4-NH2 was designed and synthesized in two steps and applied effective removal of malachite green (MG), crystal violet (CV), and methylene blue (MB) from water samples. Characterization of the newly synthesized MgFe2O4-NH2-HKUST-1 was performed by various techniques such as Fourier transform infrared spectroscopy, X-ray diffraction, Field emission scanning electron microscopy, Brunauer–Emmett–Teller, Thermal gravimetric analysis, and Vibration sampling magnetometry. Malachite green, crystal violet and methylene blue are toxic and mutagenic dyes that can be released into the water in different ways and cause many problems for human health and the environment. The removal of malachite green, crystal violet, and methylene blue from aqueous solutions was investigated using the magnetic HKUST-1 in this research. The effect of various parameters such as pH, amount of sorbent, dye concentration, temperature, and contact time on dye removal has been studied. The results showed that more than 75% of dyes were removed within 5 min. Adsorption isotherms, Kinetic, and thermodynamic studies were investigated. The results of this study show that adsorption capacity of the magnetic adsorbent is equal to 108.69 mg g−1 for MG, 70.42 mg g−1 for CV, and 156.25 mg g−1 for MB. This study shows the good strategy for the synthesis of the functionalized magnetic form of HKUST-1 and its capability for increasing the efficiency of the removal process of malachite green, crystal violet, and methylene blue from an aqueous solution. [ABSTRACT FROM AUTHOR]

In this study, we used solvent assisted mechano-synthesis strategies to form multifunctional organic–inorganic nanocomposites capable of removing both organic and inorganic contaminants. A zeolite X (Ze) and activated carbon (AC) composite was synthesized via state-of-the-art mechanical mixing in the presence of few drops of water to form Ze/AC. The second composite (Ze/L/AC) was synthesized in a similar fashion, however this composite had the addition of disodium terephthalate as a linker. Both materials, Ze/AC and Ze/L/AC, were characterized using scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), Powdered X-ray diffraction (P-XRD), Fourier-transform infrared spectrometry (FTIR), Accelerated Surface Area and Porosimetry System (ASAP), and thermal gravimetric analysis (TGA). The SEM–EDS displayed the surface structure and composition of each material. The sodium, oxygen and carbon contents increased after linker connected Ze and AC. The P-XRD confirmed the crystallinity of each material as well as the composites, while FTIR indicated the function groups (C=C, O–H) in Ze/L/AC. The contaminant adsorption experiments investigated the effects of pH, temperature, and ionic strength on the adsorption of methylene blue (MB) and Co(II) for each material. In MB adsorption, the first-order reaction rate of Ze/L/AC (0.02 h−1) was double that of Ze/AC (0.01 h−1). The reaction rate of Ze/L/AC (4.8 h−1) was also extraordinarily higher than that of Ze/AC (0.6 h−1) in the adsorption of Co(II). Ze/L/AC composite achieved a maximum adsorption capacity of 44.8 mg/g for MB and 66.6 mg/g for Co(II) ions. The MB adsorption of Ze/AC and Ze/L/AC was best fit in Freundlich model with R2 of 0.96 and 0.97, respectively, which indicated the multilayer adsorption. In the Co(II) adsorption, the data was highly fit in Langmuir model with R2 of 0.94 and 0.92 which indicated the monolayer adsorption. These results indicated both materials exhibited chemisorption. The activation energy of Ze/L/AC in MB adsorption (34.9 kJ mol−1) was higher than that of Ze/L/AC in Co (II) adsorption (26 kJ mol−1). [ABSTRACT FROM AUTHOR]

Industrial effluents are a leading major threat for water contamination, subsequently which results in severe health associated risks. Hence, purifying wastewater before releasing into the water resources is essential to avoid contamination. In this study, ZnO/Cu-DPA nano-composites were prepared by altering the percentage of Cu-DPA (20%, 30%, 40%, and 50% which are denoted to be ZnO/20%Cu-DPA, ZnO/30%Cu-DPA, ZnO/40%Cu-DPA and ZnO/50%Cu-DPA) using a simple mechanical grinding process. Several spectroscopic studies were employed such as electron paramagnetic analysis (EPR), powdered X-ray diffractometer (PXRD), UV–Vis absorbance spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscope to characterize these nano-composites. The photo-catalytic activities of the prepared nano-composites were studied by degrading MB under visible light irradiation. ZnO, ZnO/20%Cu-DPA, ZnO/30%Cu-DPA, ZnO/40%Cu-DPA and ZnO/50%Cu-DPA degradation efficiencies were determined to be 71.8, 78.5, 77.1, and 66.1%, respectively. Among the composite catalysts, the ZnO/20%Cu-DPA coupled system are demonstrated the best efficiency (87%) for photo-degradation of MB within 80 min when exposed to visible light. The ZnO/Cu-DPA nano-composites had a greater MB photodegradation efficiency than pristine ZnO owing to p-n heterojunction in the linked system. Under visible light irradiation, the ZnO/20%Cu-DPA catalysed the conversion of dissolved O2 to hydroxyl radicals (OH·), triggering the reduction of MB. This suggests that ·OH is the primary specific active radical involved in the photo-catalytic decomposition of MB. Furthermore, EPR analysis indicates the existence of ·OH in the photo-catalytic system. The proposed nano-composites (ZnO/20%Cu-DPA) reusability was investigated across three cycles as the most efficient photo-catalyst. The results show that, the ZnO/Cu-DPA nano-catalyst is a potential candidate for the remediation of dirty water. [ABSTRACT FROM AUTHOR]

Biochar is a potential porous carbon to remove the contaminants from aquatic environments. Herein, N-doped hierarchical biochar was produced by the combined approach of ammonia torrefaction pretreatment (ATP) and alkali activation. ATP could not only incorporate N element into poplar wood, but obtain the loose structure of poplar wood. The highest surface area of N-doped hierarchical biochar was 2324.61 m2 g−1 after ammonia wet torrefaction pretreatment, which was higher than that of activation carbon (1401.82 m2 g−1) without torrefaction pretreatment, the hierarchical biochar (2111.03 m2 g−1) without ammonia atmosphere. The N-doped hierarchical biochar presented the highest adsorption capacity (564.7 mg g−1) of methyl orange (MO), which was 14.64-fold of that on biochar without N doping. In addition, the pseudo-second-order and Langmuir model fitted well with the adsorption kinetics and isotherms of the N-doped hierarchical biochar. The incorporation of nitrogen element could not only tune the distribution of surface electrons on biochar, but optimize the ambient condition of adsorption active sites as well. The adsorption of MO might occur on the N-/O-containing functional groups through the electrostatic interaction, the π-π dispersion interaction, and the hydrogen bonding. The density functional theory showed that the graphitic-N and pyridinic-N were the dominant adsorption active sites. Highlights: Ammonia torrefaction pretreatment coupled with alkali activation was developed for the preparation of N-doped hierarchical biochar. AWTP had better performance on N-doping and increasing of BET than ADTP. Graphitic-N and pyridinic-N were dominant active sites for the adsorption of organic dye. [ABSTRACT FROM AUTHOR]

From the perspective of environmental protection, the highly efficient degradation of antibiotics and organic dyes in wastewater needs to be tackled as soon as possible. In this study, an ecofriendly and green cube-shaped cobalt-doped zinc oxide nanoparticles (Co–ZnO NPs) photocatalyst using Pterocladia Capillacea (P. Capillacea) water extract loaded with 5, 10, and 15% cobalt ions were formed via co-precipitation process to degrade antibiotics. The prepared Co–ZnO NPs were tested as a photocatalyst for the photodegradation of ciprofloxacin (CIPF) in the presence of a visible LED-light source. Co–ZnO NPs have been obtained through the co-precipitation method in the presence of P. Capillacea extract as a green capping agent and reducing agent, for the first time. Several characterization techniques including FTIR, XRD, BET, XPS, TEM, EDX, SEM, TGA and DRS UV–Vis spectroscopy were applied to study the prepared Co–ZnO NPs. XRD results suggested that the average size of these NPs ranged between 42.82 and 46.02 nm with a hexagonal wurtzite structure. Tauc plot shows that the optical energy bandgap of ZnO NPs (3.19 eV) gradually decreases to 2.92 eV by Co doping. Examinations showed that 5% Co–ZnO NPs was the highest efficient catalyst for the CIPF photodegradation when compared with ZnO NPs and other 10 and 15% Co–ZnO NPs. A 10 mg/L solution of CIPF was photo-degraded (100%) within the first 15 min irradiation. The kinetics showed that the first-order model is suitable for displaying the rate of reaction and amount of CIPF elimination with R2 = 0.952. Moreover, central composite design optimization of the 5% Co-doped ZnO NPs was also investigated. [ABSTRACT FROM AUTHOR]

Inhomogeneity in single molecule electron transfer at the surface of lipid in a single vesicle has been explored by single molecule spectroscopic technique. In our study we took Di-methyl aniline (DMA), as the electron donor (D) and three different organic dyes as acceptor. These dyes are C153, C480 and C152 and they reside in different regions in the vesicle depending upon their preference of residence. For each probe, we found fluctuations in the single-molecule fluorescence decay, which are attributed to the variation in the reactivity of interfacial electron transfer. We found a non-exponential auto-correlation fluctuation of the intensity of the probe, which is ascribed to the kinetic disorder in the rate of electron transfer. We have also shown the power law distribution of the dark state (off time), which obeys the levy's statistics. We found a shift in lifetime distribution for the probe (C153) from 3.9 ns to 3.5 ns. This observed quenching is due to the dynamic electron transfer. We observed the kinetic disorderness in the electron transfer reaction for each dye. This source of fluctuation in electron transfer rate may be ascribed to the inherent fluctuation, occurring on the time scale of ~ 1.1 ms (for C153) of the vesicle, containing lipids. [ABSTRACT FROM AUTHOR]

Numerous catalysts for water pollutant mitigation have been developed over recent decades. However, the utilization of catalysts embedded in 3D structures remains challenging. This study aims at fabricating 3D-printed TiO2/SiO2/polymer scaffolds for the degradation of organic dyes, specifically Methylene Blue (MB) and rhodamine B (Rh B). The TiO2/SiO2/polymer scaffolds were fabricated by stereolithography (SLA) technique, using TiO2 photocatalyst synthesized via a solution combustion process, silica adsorbent prepared from sugarcane leaves, and photocurable resin as feedstock. X-ray diffraction analysis confirmed that TiO2 exhibited anatase/rutile/brookite triphasic structure while SiO2 possessed amorphous structure. Scanning electron micrographs revealed that TiO2 and SiO2 particles uniformly deposited on the surface of the photocurable resin. The adsorption activity of the TiO2/SiO2/polymer scaffolds was examined in the dark for 24 h to ensure that adsorption equilibrium was achieved. Photocatalytic examinations were conducted under UV light (λ = 365 nm). The TiO2/SiO2/polymer scaffolds efficiently demonstrated their potential dye removal efficiency against MB and Rh B dyes as 81.9% and 60%, respectively. Reusability testing revealed that after hydrogen peroxide treatment, the used scaffolds exhibited the degradation ability in a comparable range to the as-fabricated scaffolds. An application of a 3D printing technique for water pollution reduction was successfully demonstrated in this study. [ABSTRACT FROM AUTHOR]

A novel, magnetic HKUST-1 MOF based on MgFe2O4-NH2 was designed and synthesized in two steps and applied effective removal of malachite green (MG), crystal violet (CV), and methylene blue (MB) from water samples. Characterization of the newly synthesized MgFe2O4-NH2-HKUST-1 was performed by various techniques such as Fourier transform infrared spectroscopy, X-ray diffraction, Field emission scanning electron microscopy, Brunauer–Emmett–Teller, Thermal gravimetric analysis, and Vibration sampling magnetometry. Malachite green, crystal violet and methylene blue are toxic and mutagenic dyes that can be released into the water in different ways and cause many problems for human health and the environment. The removal of malachite green, crystal violet, and methylene blue from aqueous solutions was investigated using the magnetic HKUST-1 in this research. The effect of various parameters such as pH, amount of sorbent, dye concentration, temperature, and contact time on dye removal has been studied. The results showed that more than 75% of dyes were removed within 5 min. Adsorption isotherms, Kinetic, and thermodynamic studies were investigated. The results of this study show that adsorption capacity of the magnetic adsorbent is equal to 108.69 mg g−1 for MG, 70.42 mg g−1 for CV, and 156.25 mg g−1 for MB. This study shows the good strategy for the synthesis of the functionalized magnetic form of HKUST-1 and its capability for increasing the efficiency of the removal process of malachite green, crystal violet, and methylene blue from an aqueous solution. [ABSTRACT FROM AUTHOR]

In this work, seven organic dyes were designed (M2–M7) to have the D-π1-Ai-π2-A structure from the reference dye M1, which has the D-π1-π2-A structure. By inserting different auxiliary acceptors Ai (i = 1–7) between the π1 and π2 onto the reference dye M1, we obtained the designed dyes to study their photovoltaic properties for use in DSSC devices. The geometrical structures, absorption spectrum properties, nonlinear optical properties (NLOs), energy levels, frontier molecular orbitals, and some photovoltaic parameters were theoretically investigated using density function theory (DFT) and time-dependent DFT (TD-DFT) methods, with the aim of improving the DSSC performance of the designed dyes. The theoretical results reveal that the designed dyes would be used as potential sensitizers in DSSCs due to their very small energy gaps, broad absorption spectra, higher NLO properties, lower reorganization energy (λtot), lower regeneration driving force (ΔGreg), longer excited lifetime (τ), higher vertical dipole moment (µnormal), reasonable electron injection driving force (∆Ginj), and equally reasonable light-harvesting efficiency (LHE) compared to the reference dye M1. Furthermore, the designed dyes (M2–M8) have better charge transferability, the highest stabilization energy, and the highest ability of electron-donating and electron-accepting, resulting in a high short-circuit current and better power conversion energy (PCE) compared to reference dye M1. These results show that the introduction of different auxiliary acceptors Ai can most effectively improve the photovoltaic performance of our system. [ABSTRACT FROM AUTHOR]