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Purpose: The accuracy of surgery for patients with solid tumors can be greatly improved through fluorescence-guided surgery (FGS). However, existing FGS technologies have limitations due to their low penetration depth and sensitivity/selectivity, which are particularly prevalent in the relatively short imaging window (< 900 nm). A solution to these issues is near-infrared-II (NIR-II) FGS, which benefits from low autofluorescence and scattering under the long imaging window (> 900 nm). However, the inherent self-assembly of organic dyes has led to high accumulation in main organs, resulting in significant background signals and potential long-term toxicity. Methods: We rationalize the donor structure of donor–acceptor-donor-based dyes to control the self-assembly process to form an ultra-small dye nanocluster, thus facilitating renal excretion and minimizing background signals. Results: Our dye nanocluster can not only show clear vessel imaging, tumor and tumor sentinel lymph nodes definition, but also achieve high-performance NIR-II imaging-guided surgery of tumor-positive sentinel lymph nodes. Conclusion: In summary, our study demonstrates that the dye nanocluster-based NIR-II FGS has substantially improved outcomes for radical lymphadenectomy. [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]

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]

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]

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 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]

Leather dyeing is a critical step in leather manufacturing, as it is responsible for providing leather products with an eye-catching visual aspect and adequate quality properties to meet customers' expectations. This step is becoming more and more challenging as the leather industry advances hand in hand with new environmentally friendly policies and regulations to achieve a safer and healthier planet by replacing the highly polluting Cr-based leather tanning technology with greener alternatives. As a result, achieving high-performance dyeing of organic chrome-free leather is one of the bottlenecks for the sustainable development of the leather industry. Herein, we propose a novel strategy to fabricate an isocyanate-based oligomeric dye (IBD) with high coloring capabilities (component content higher than 62.8%) based on toluene 2,4-diisocyanate and reactive red dye 180. This material has been tested for the dyeing of biomass-derived aldehyde (BDA)-tanned leather with excellent outcomes. The experimental results showed that the crust leather dyed with our novel IBD dyeing agent had higher color fastness and better fullness than the leather dyed with conventional anionic (CAD) or reactive red 180 (RRD-180) dyes. These excellent and promising results open new avenues in manufacturing high-performance organic Cr-free leather products and help to ensure the sustainable transition of the leather industry from Cr-based leather tanning to more sustainable alternatives, maintaining the final quality of the leather products. [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]

The removal of multiple organic dyes contained in industrial wastewater poses a significant challenge, and the underlying mechanisms involved in their simultaneous removal are still not fully understood. In this work, Nickel–Iron layered double hydroxides nanosheets were successfully synthesized by coprecipitation method at constant pH and were characterized by powder x-ray diffraction, Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, and their effectiveness in removing anionic dyes Remazol Red 23, and Indigo Carmine was investigated by studying several parameters such as initial solution pH, adsorbent dose, dye concentration, and temperature effect. The as-prepared nanocomposite exhibited excellent removal efficiency for Remazol Red 23 and Indigo Carmine reaching the maximum adsorption capacities of 133.04 mg.g−1 and 115.59 mg.g−1, respectively. The simultaneous removal of binary anionic dye mixture was studied and proved the high performance of the synthesized material due to the electrostatic attraction. Also, a cationic dye Basic Yellow 28 was successfully removed when it was added to the binary anionic dyes' mixture, and this was explained by two proposed mechanisms: surface charge modification and the synergetic effect of dyes molecules. [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]

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]

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]

Natural dyes have been widely employed in the fabrication of dye-sensitized solar cells (DSSCs). DSSCs are favored for their cost-effective, and simple fabrication process relies on metal-based and organic dyes. The choice of dyes greatly affects the performance of DSSCs. DSSCs have found a lot of applications in indoor, solar power gadgets with reasonable efficiency up to 13%. Nonetheless, despite advances in DSSC technology, the complex photophysics and excited state dynamics associated with natural dyes employed in DSSCs remain elusive and have not been adequately investigated. This information gap emphasizes the need for more study and analysis into the behavior of these dyes, since understanding their underlying principles might lead to major improvements in DSSC performance and efficiency. In this work, we have investigated the fundamental characteristics and excited-state carrier dynamics of natural dye curcumin using ultrafast transient absorption (TA) spectroscopy technique. The curcumin dye shows delay time-dependent positive and negative signals in the TA spectra, which are related to excited state absorption and stimulated emission. We also found that hydrogen bonding and polarity effect of solvent significantly influence the carrier dynamics of curcumin. Ultrafast lifetime component indicates that hydrogen-bond rearrangements are involved in the kinetics of the relaxation process of the S1 state of curcumin photo-sensitizer. [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]

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]

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]

The importance of water for all living organisms is unquestionable and protecting its sources is crucial. In order to reduce water contaminants, like toxic metals and organic dyes, researchers are exploring different techniques, such as adsorption, photocatalytic degradation, and electrolysis. Novel materials are also being sought. In particular, biopolymers like guar gum and xanthan gum, that are eco-friendly, non-toxic, reusable, abundant and cost-effective, have enormous potential. Gum-based nanocomposites can be prepared and used for removing heavy metals and colored dyes by adsorption and degradation, respectively. This review explains the significance of gum-based nanomaterials in waste water treatment, including preparative steps, characterization techniques, kinetics models, and the degradation and adsorption mechanisms involved. [ABSTRACT FROM AUTHOR]

In this study, a green and effective adsorbent of chitosan/montmorillonite/algae (CHI/MMT/ALG) composite was developed to be an alternative adsorbent to remove dyestuffs including basic green 1 (BG1) and reactive blue 19 (RB19) from the aqueous solutions. The physicochemical characteristics of CHI/MMT/ALG were analyzed using XRD, CHN–O, BET, FTIR, pHpzc, and SEM analytical techniques. The findings of the characterization revealed that the increased surface functionalities offered an enticing platform for the improved adsorption of cationic and anionic dye molecules. The essential adsorption variables, such as A: CHI/MMT/ALG dosage (0.02–0.08 g), B: pH (4–9), and C: duration (5–30 min), were optimized using the Box-Behnken design (BBD) approach. The BG1 adsorption process demonstrated a better match with the Langmuir model, whereas the RB19 adsorption process exhibited a better fit with both the Temkin and Langmuir models. The fitting of the kinetic analysis illustrates that the BG1 and RB19 adsorption by CHI/MMT/ALG could be better represented by a pseudo-second-order model. The maximum adsorption capacity of CHI/MMT/ALG for BG1 and RB19 was specified to be 509.5 mg/g and 227.9 mg/g, respectively. The endothermicity and spontaneity of the BG1 and RB19 adsorption processes are evidenced by thermodynamic analysis. The improved surface functionalities of CHI/MMT/ALG inspired the adsorption mechanism of CHI/MMT/ALG for BG1 and RB19 could be essentially ascribed by electrostatic attraction, n-π stacking, and hydrogen bonding. Overall, the study's findings indicate that the newly developed CHI/MMT/ALG has significant potential for the removal of synthetic dye from aqueous. [ABSTRACT FROM AUTHOR]

There has been a lot of attention on water pollution by dyes in recent years because of their serious toxicological implications on human health and the environment. Therefore, the current study presented a novel polyethylene glycol-functionalized graphene oxide/chitosan composite (PEG-GO/CS) to remove dyes from aqueous solutions. Several characterization techniques, such as SEM, TEM, FTIR, TGA/DTG, XRD, and XPS, were employed to correlate the structure–property relationship between the adsorption performance and PEG-GO/CS composites. Taguchi's (L25) approach was used to optimize the batch adsorption process variables [pH, contact time, adsorbent dose, and initial concentration of methyl orange (MO)] for maximal adsorption capacity. pH = 2, contact time = 90 min, adsorbent dose = 10 mg/10 mL, and MO initial concentration = 200 mg/L were found to be optimal. The material has a maximum adsorption capacity of 271 mg/g for MO at room temperature. With the greatest R2 = 0.8930 values, the Langmuir isotherm model was shown to be the most appropriate. Compared to the pseudo-first-order model (R2 = 0.9685), the pseudo-second-order model (R2 = 0.9707) better fits the kinetic data. Electrostatic interactions were the dominant mechanism underlying MO sorption onto the PEG/GO-CS composite. The as-synthesized composite was reusable for up to three adsorption cycles. Thus, the PEG/GO-CS composite fabricated through a simple procedure may remove MO and other similar organic dyes in real contaminated water. [ABSTRACT FROM AUTHOR]

In this study, the chemical pechini sol-gel method was used for the simple fabrication of Fe0.5Mn0.5Co2O4/Fe2O3 as a new nanocomposite at 400, 600, 800, and 1000 oC. The fabricated products at 400, 600, 800, and 1000 oC were encoded as E400, E600, E800, and E1000, respectively. The fabricated nanocomposites were identified using several devices such as XRD, N2 adsorption/desorption analyzer, FT-IR, EDS, UV–Vis diffuse reflectance spectrophotometer, and field emission scanning electron microscopy. The average crystallite size of the E400, E600, E800, and E1000 products is 80.31, 123.25, 130.75, and 141.36 nm, respectively. The FE-SEM showed that the E400 sample consists of rods, spheres, and irregular forms with an average diameter of 337.50 nm. Also, the E600 and E800 products consist of spheres and irregular shapes with an average diameter of 446.96 and 854.52 nm, respectively. Besides, the E1000 product comprises of cubic, sphere, and irregular shapes with a mean diameter of 1019.88 nm. The synthesized nanocomposites were used for the efficient photocatalytic degradation of safranin dye. In the presence of H2O2, 0.1 g of the synthesized nanocomposites completely decompose 50 mL of about 25 mg/L of safranin dye at pH equals 8 in 25 min. [ABSTRACT FROM AUTHOR]

Context: The organic solar cells (OSCs) are being developed with the goal of improving their photovoltaic capabilities. Here, utilizing computational methods, six new nonfullerene acceptors (NFA) comprising dyes (A1–A6) have been created by end-group alterations of the Y123 framework as a standard (R). Methods: The DFT-based investigations at B3LYP/6-31G + (d,p) level were applied to evaluate their properties. The planar geometries associated with these structures, which lead to improved conjugation, were validated by the estimation of molecular geometries. Dyes A1–A6 have shorter Egap than R, according to a frontier molecular orbital (FMO) investigation, which encourages charge transfer in them. The dyes with their maximum absorption range were shown by optical properties to be 692–711 nm, which is significantly better than R with its 684 nm range. Their electrostatic and Mulliken charge patterns provided additional evidence of the significant separation of charges within these structures. All the dyes A1–A6 had improved light harvesting efficiency (LHE) values as compared to Y123, highlighting their improved capacity to generate charge carriers by light absorption. With the exception of dye A4, all newly developed dyes might have a superior rate of charge carrier mobility than R, according to reorganization energies λre. Dyes A3 and A4 had the greatest open-circuit voltage (Voc). Dye A3 exhibited improvement in all of its examined properties, making it a promising choice in DSSC applications. [ABSTRACT FROM AUTHOR]

Using a combination method of roasting process with soda ash (Na2CO3) and hydrochloric acid leaching, a TiO2-based photocatalyst was successfully synthesized from Indonesia ilmenite ore. The study investigated the effect of Na2CO3 ratios, roasting times, and HCl concentration on the physical and photocatalytic properties of the photocatalyst. The results revealed that HCl concentration played a critical role in altering the characteristics of the prepared photocatalyst. TiO2 composition increased by 61% compared to ilmenite ore when 20% HCl was used, whereas Fe2O3 composition decreased by 88%. The physical properties and photocatalytic activity of the prepared TiO2 were similar to those of low-grade commercial TiO2. When conducted to 3 h of low-power (8 W) UV light irradiation, the photocatalyst decomposed Eriochrome Black-T, an organic dye model pollutant, by up to 83%. This study's findings provide crucial implications for further research on recovering TiO2-based photocatalyst from ilmenite ore using a simple method. [ABSTRACT FROM AUTHOR]

This study presents a functional magnetic cellulose-based nanocomposite (mCNFAP/PMAA) to develop a highly efficient and sustainable adsorbent to remove organic dyes from an aqueous solution. Cellulose was extracted from Arenga Pinnata (AP) and was modified with 2,2,6,6-Tetramethyl-1-piperidinyloxy (TEMPO) to convert carboxyl end groups on cellulose chains that contribute to magnetization reaction. Methacrylic acid, an environmentally friendly monomer carrying carboxylic acid functional groups, was grafted on magnetic cellulose for effective cationic dye removal. The mCNFAP/PMAA nanocomposite structure was characterized by XRD, SEM/EDS, TGA, VSM, and FTIR. X-ray diffraction patterns indicated the successful extraction of cellulose from AP and the incorporation of the magnetic core. The SEM/EDS examinations referred to the existence of Fe3O4 nanoparticles and the grafting of PMAA on the surface of magnetic cellulose. At the same time, VSM results demonstrated that the saturation magnetization value of mCNFAP/PMAA was 15.5 emu/g, enabling the nanocomposite can be rapidly and easily separated from the aqueous solution under an external magnetic field. The adsorption and desorption behavior of mCNFAP/PMAA in batch and continuous lab-scale systems were evaluated using isotherm and kinetic models. The adsorption study revealed that the pH did not significantly affect on adsorption behavior of MB and the maximum adsorption capacity of mCNFAP/PMAA was 201 mg/g. The adsorption kinetic and isotherm models were well-fitted to the pseudo-second-order model and Langmuir isotherm. Notably, the regeneration performance of the mCNFAP/PMAA was excellent and protected its 75% capacity after the fifteenth adsorption/desorption cycle. The fixed column was used to determine the real-time behavior of the adsorbent in lab-scale continuous mode and the data were analyzed in models such as Thomas, Adams, and Yoon Nelson. The maximum adsorption capacity was found to be 264.65 mg/g. In conclusion, mCNFAP/PMAA composite is an effective and cheap material from sustainable sources. Due to its high regeneration and reusability capability, it could be employed as an effective adsorbent in removing pollutants from wastewater. [ABSTRACT FROM AUTHOR]

Globally, treating and disposing of industrial pollutants is a techno-economic challenge. Industries' large production of harmful heavy metal ions (HMIs) and dyes and inappropriate disposal worsen water contamination. Much attention is required on the development of efficient and cost-effective technologies and approaches for removing toxic HMIs and dyes from wastewater as they pose a severe threat to public health and aquatic ecosystems. Due to the proven superiority of adsorption over other alternative methods, various nanosorbents have been developed for the efficient removal of HMIs and dyes from wastewater and aqueous solutions. Being a good adsorbent, conducting polymer-based magnetic nanocomposites (CP-MNCPs) has drawn more attention for HMIs and dye removal. Conductive polymers' pH-responsiveness makes CP-MNCP ideal for wastewater treatment. The composite material absorbed dyes and/or HMIs from contaminated water could be removed by changing the pH. Here, we review the production strategies and applications of CP-MNCPs for HMIs and dye removal. The review also sheds light on the adsorption mechanism, adsorption efficiency, kinetic and adsorption models, and regeneration capacity of the various CP-MNCPs. To date, various modifications to conducting polymers (CPs) have been explored to improve the adsorption properties. It is evident from the literature survey that the combination of SiO2, graphene oxide (GO), and multi-walled carbon nanotubes (MWCNTs) with CPs-MNCPs enhances the adsorption capacity of nanocomposites to a large extent, so future research should lean toward the development of cost-effective hybrid CPs-nanocomposites. [ABSTRACT FROM AUTHOR]

Fabrication of heterojunction semiconductors for the photodegradation of toxic organic dyes under sunlight exposure has earned significant recognition from researchers nowadays. On that account, we have synthesized and explored a comparative photodegradation study of ZnO/CuO nanocomposite with ZnO and CuO nanoparticles. ZnO and CuO nanoparticles have been synthesized by biosynthesis methods using Ficus benghalensis leaf extract. As-synthesized ZnO and CuO nanoparticles have been further utilized for the synthesis of ZnO/CuO nanocomposite by the mortar pestle crushing/milling method. Both biosynthesis methods and mortar pestle crushing/milling methods are simple, low-cost, and environmentally friendly. Structural, optical, and morphological analysis of all the synthesized nanomaterials have been done by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), field emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS), fourier transform infrared spectroscopy (FTIR), and UV–visible spectroscopy. PXRD data reveal that synthesized ZnO nanoparticles are in the hexagonal wurtzite phase, CuO nanoparticles in the monoclinic phase, and ZnO/CuO nanocomposite in the hexagonal wurtzite as well as in monoclinic phase. FE-SEM and TEM images of ZnO/CuO nanocomposite reveal the nanorod-shaped morphology along with micro-sized and nano-sized flakes. The BET analysis shows the surface areas 18.128 m2/g for ZnO nanoparticles, 16.653 m2/g for CuO nanoparticles, and 19.580 m2/g for ZnO/CuO nanocomposite, respectively. The energy band gap values of ZnO/CuO nanocomposite are obtained 3.13 eV for ZnO and 2.76 eV for CuO, respectively. The photocatalytic behaviors of all the synthesized nanomaterials are examined against aqueous dye solutions of methylene blue (MB), rhodamine B (RhB), and methyl orange (MO) under sunlight irradiation. The results reveal that the photocatalytic degradation efficiency of ZnO/CuO nanocomposite has been found higher than with ZnO and CuO nanoparticles for all the dyes. Also, all the synthesized nanomaterials indicate higher photocatalytic degradation efficiency for methylene blue dye among all three dyes. The kinetics of photodegradation of all the dye solutions has also been investigated in the presence of ZnO, CuO, and ZnO/CuO photocatalysts separately. The results exhibit that rate constant values for all the dyes are higher with ZnO/CuO nanocomposite than with ZnO and CuO nanoparticles. ZnO/CuO nanocomposite demonstrates degradation efficiency for MB dye 99.13%, for RhB 80.21%, and for MO 67.22% after 180 min of sunlight exposure. ZnO/CuO nanocomposite and ZnO and CuO nanoparticles also show the best reusability and stability up to three cycles for photocatalytic degradation of MB dyes among all the dyes. Therefore, green synthesized ZnO/CuO nanocomposite could be used as an efficient photocatalyst for the degradation of various toxic dyes. The mineralization of different dyes using ZnO/CuO nanocomposite has been examined by FTIR analysis. Furthermore, the mineralization of MB dye has been done by total organic carbon (TOC) measurements. [ABSTRACT FROM AUTHOR]

The discharge of organic dye pollutants in natural water bodies has put forward a big challenge of providing clean water to a large part of the population. As the population is increasing with time, only underground water is not sufficient to complete the water requirements of everyone everywhere. Purification of wastewater and its reuse is the only way to fulfill the water needs. Nanotechnology has been used very efficiently for wastewater treatment via photocatalytic degradation of dye molecules. In the past few years, a lot of investigations have been done to enhance the photocatalytic activity of metal oxide semiconductors for water purification. In this review, we have discussed the different methods of synthesis of various metal oxide semiconductor nanoparticles, energy band gap, their role as efficient photocatalysts, radiations used for photocatalytic reactions, and their degradation efficiency to degrade the dye pollutants. We have also discussed the nanocomposites of metal oxide with graphene. These nanocomposites have been utilized as the efficient photocatalyst due to unique characteristics of graphene such as extended range of light absorption, separation of charges, and high capacity of adsorption of the dye pollutants. [ABSTRACT FROM AUTHOR]

The present work aims to fabricate of graphene oxide (GO) nanosheets-yttrium oxide (Y2O3)–silicon oxide (SiO2) ternary nanostructures as high photo-degradation activity against pollutants of organic dyes. The GO nanosheets were added to Y2O3/SiO2 nanostructures with ratios 5%, 10% and 15%. The structural and photo-degradation characteristics of Y2O3/SiO2/GO nanostructures were studied. The structural characteristics included X-ray diffraction (XRD) and scanning electron microscope (SEM). Results of X-ray indicated that no reaction between components. SEM micrographs showed high distribution of GO nanosheets inside the Y2O3/SiO2 nanostructures. The photo-degradation against organic dyes improved from 1.17% for Y2O3/SiO2 nanostructures to 52% when the concentration of GO nanosheets reached 15 wt% at time (45 min). The dye concentration reduced with an increase in the nanomaterials content and irradiation time. Finally, the obtained results indicated that the Y2O3/SiO2/GO nanostructures have individual activity for photo-degradation of organic dyes which can be considered as key to remove the pollutants of organic dyes with elevated activity, short time, low nanomaterials concentration and few cost compared of others nanomaterials. [ABSTRACT FROM AUTHOR]

In the present investigation a promising conducting polymer, Polyaniline (PANI), and ZrO2-PANI nanocomposite are used for photocatalytic degradation of Carbol Fuchsin (CF) dye. Both materials were prepared via the in-situ polymerization method. Various nano-characterization techniques were used to investigate the fabricated materials. The structural investigation of ZrO2 and ZrO2-PANI nanocomposite was performed using X-ray diffraction (XRD). From this investigation, it was observed that ZrO2 belongs to the crystalline tetragonal phase possessing a crystallite size of 15.80 nm. The SEM analysis shows the flakes arrangement for undoped ZrO2, while improved agglomeration has been observed for modified ZrO2-PANI nanocomposite. The Raman shifts can be observed from Raman spectroscopy for both the fabricated materials. Organic dyes are considered to be persistent organic pollutants (POP's) that are toxic in nature. Here one of the POP dyes, CF was used in the photocatalytic efficiency of ZrO2 and ZrO2-PANI nanocomposite. The prepared polymerized catalysts are porous, possessing a high surface area with a tuned band gap, and are found very persistent, and rapid, for the water purification process via the Advanced Oxidation Process. The fabricated catalyst degrades the CF dye within 30 min. [ABSTRACT FROM AUTHOR]

Malachite green (MG) is an organic dye and belongs to triphenylmethane category which is more harmful and toxic carcinogenic compound. In conventional methods for dye treatment, many metal ions and harmful chemicals were used. But in our study, we have proposed completely an eco-friendly method for dye degradation using carbon quantum dots (CQDs) from Spirulina platensis which is purely a natural and novel source of carbon-rich matter. The synthesized CQDs were characterized by TEM, SEM, particle size analyzer and fluorescence spectrophotometer. Sunlight promotes the photocatalytic activity of CQDs and degraded metabolites were analyzed by Gas chromatography–Mass spectrometry (GC–MS). Additionally, small quantity of synthesized CQDs acted as an efficient photocatalyst against 25 ppm concentration of MG dye and degradation was occurred within 3 h. 71% of BOD, 71.6% of COD and 78% of TOC were reduced by charcoal and it also helps to remove the CQDs from treated water by improving the quality of treated water with corresponding optical and physicochemical parameters. Based on the results of MG dye degradation, we have successfully done preliminary work for reactive blue MR and textile effluent degradation. A significant recycling process for degraded water was studied using phytotoxicity test and to prove that it does not possess any hazardous matter. [ABSTRACT FROM AUTHOR]

Herein, a novel nanocomposite, namely, Zn-modified CeO2@biochar (Zn/CeO2@BC), is synthesized via facile one-step sol-precipitation to study its photocatalytic activity towards the removal of methylene blue dye. Firstly, Zn/Ce(OH)4@biochar was precipitated by adding sodium hydroxide to cerium salt precursor; then, the composite was calcined in a muffle furnace to convert Ce(OH)4 into CeO2. The crystallite structure, topographical and morphological properties, chemical compositions, and specific surface area of the synthesized nanocomposite are characterized by XRD, SEM, TEM, XPS, EDS, and BET analysis. The nearly spherical Zn/CeO2@BC nanocomposite has an average particle size of 27.05 nm and a specific surface area of 141.59 m2/g. All the tests showed the agglomeration of Zn nanoparticles over the CeO2@biochar matrix. The synthesized nanocomposite showed remarkable photocatalytic activity towards removing methylene blue, an organic dye commonly found in industrial effluents. The kinetics and mechanism of Fenton-activated dye degradation were studied. The nanocomposite exhibited the highest degradation efficiency of 98.24% under direct solar irradiation of 90 min, at an optimum dosage of 0.2 g l−1 catalyst and 10 ppm dye concentration, in the presence of 25% (V/V) 0.2 ml (4 µl/ml) hydrogen peroxide. The hydroxyl radical generated from H2O2 during the photo-Fenton reaction process was attributed to the nanocomposite's improved photodegradation performance. The degradation process followed pseudo-first-order kinetics having a rate constant (k) value of 0.0274 min−1. [ABSTRACT FROM AUTHOR]

Multifunctional hybrid hydrogels based on chitosan (CS) and poly(vinyl alcohol) (PVA), chemically crosslinked with genipin (GEN), and filled with multi-walled carbon nanotubes (MWCNTs) were synthesized and characterized to be used as dye adsorbents in polluted water. Solutions (10 - 5 M) of methyl orange (MO) and acid blue 113 (AB) were tested. Each dye solution was analyzed in initial acid and basic pH conditions (pH 6.02 ± 0.2 and 10.0 ± 0.4). The physicochemical, mechanical properties, dye removal efficiency, adsorption kinetics, and possible hybrid hydrogels' adsorption mechanism were examined. Incorporating GEN enhanced the polymeric network structure and the mechanical stability of CS/PVA-based hydrogels; their elastic modulus increased to ninefold even in aqueous acid media. The CS/PVA/GEN and CS/PVA/GEN/MWCNTs hydrogels presented removal efficiencies up to 96.8% and 93.2% (0.30 and 0.36 mg/g) for MO and 90–100% (0.70–0.77 mg/g) for AB. Regardless of the initial pH value of the dye solutions, all of them presented a final value of pH ~ 5, which implies that electrostatic attractions can occur during the adsorption process. Experimental data were successfully fitted to pseudo-first-order kinetics. Thus, physisorption processes acted during the removal of MO and AB. FT-IR spectroscopy demonstrated that the hydrogel's amino (–NH 2 ) and hydroxyl (–OH) groups are mainly involved in adsorption by electrostatic interactions, hydrogen bonding, n– π stacking interactions, and π – π interactions. We demonstrated that using GEN and MWCNTs in the CS/PVA blend offers a useful approach for getting resistant, efficient, and low-cost adsorbent materials to successfully deal with water pollution caused by anionic organic dyes as MO and AB, among others. [ABSTRACT FROM AUTHOR]

Achieving an ideal light-harvesting system at a low cost remains a challenge. Herein, we report the synthesis of a hybrid dye system based on tetraphenylene (TPE) encapsulated organic dyes in a continuous flow microreactor. The composite dye nanoparticles (NPs) are synthesized based on supramolecular self-assembly to achieve the co-emission of aggregation-induced emission dyes and aggregation-caused quenching dyes (CEAA). Numerical simulations and molecular spectroscopy were used to investigate the synthesis mechanism of the CEAA dyes. Nanoparticles of CEAA dyes provide a platform for efficient cascade Förster resonance energy transfer (FRET). Composite dye nanoparticles of TPE and Nile red (NiR) are synthesized for an ideal light-harvesting system using coumarin 6 (C-6) as an energy intermediate. The light-harvesting system has a considerable red-shift distance (~126 nm), high energy-transfer efficiency (ΦET) of 99.37%, and an antenna effect of 26.23. Finally, the versatility of the preparation method and the diversity of CEAA dyes are demonstrated. Developing efficient light harvesting systems at low cost is a challenge. Here, the authors synthesized coemissive dyes in a continuous flow microreactor featuring a controlled cascade FRET process combining aggregation-induced emission and quenching. [ABSTRACT FROM AUTHOR]

Incautious discharge of organic dyes such as methyl orange (MO) has produced serious pollution to the environment, calling for the efficient techniques to remove them with retaining the green world. The photo-catalytic degradation of organic dyes is promising among the developed techniques. Thus, a strategy based on transpiration-prompted photocatalytic degradation of dye pollutant under sunlight is put forward. Aniline (ANI) is graft-polymerized onto poly(acrylamide-co-N-4-aminophenylacrylamide) (PAAm) cryogel embedded with gold nanoparticles (AuNPs, diameter: 4–10 nm). The obtained cryogels integrated with AuNPs and PANI inside PAAm matrix (AuNP@PAAm-g-PANI) have been structurally explored based on the chemical composition and the phase/porous morphology. SEM and TEM observation shows that PANI and AuNPs are uniformly distributed in PAAm matrix. Since the macro-porosity of cryogel, hydrophilicity of PAAm and photo-thermal activity of PANI, PAAm-g-PANI cryogels without AuNPs can have a photo-thermal evaporation rate of water at 1.63 kg·m−2·h−1. As a comparison, AuNP@PAAm-g-PANI cryogels with AuNPs exhibit higher one at 2.20 kg·m−2·h−1, suggesting the promotion of AuNPs to photo-thermal evaporation. Meanwhile, PANI appreciatively assists AuNPs to display higher catalytic ability for the oxidative degradation of MO. Therefore, the removal of MO from water is obviously prompted by the water transpiration under sunlight with AuNP@PAAm-g-PANI cryogels, whose rate constant can reach to 0.320 h−1, being three folds of that for the sole absorption of MO. This transpiration-prompted photocatalytic degradation provides a fascinating route to eliminate organic pollutants and obtain pure water from wastewater simultaneously with sustainable sunlight energy. [ABSTRACT FROM AUTHOR]

In our present study, the photocatalytic degradation of malachite green (MG) an organic dye was carried out using a phycocyanin extract of Spirulina platensis under the irradiation of sunlight. The aim of the present study is to incorporate a simple, novel, an eco-friendly, and cost-effective degradation of dyes without using any harmful metals and chemicals. It was observed that 25 ppm of MG dye got degraded nearly to 100 % at 3 h. The UV absorbance studies indicate the absence of a peak at 620 nm which is a conclusive evidence for MG dye degradation. An optimization study of MG dye degradation was evaluated by Response Surface Methodology using Minitab module 20.4.0.0 statistical software and its percentage of degradation was statistically analyzed using analystat. The FT-IR studies of raw spectra show minimal variation; however, the deconvoluted spectra in the region of 1600–1700 cm−1 indicate the variation in the secondary structure of amide I bands that leads to the dye degradation. The dye degradation study mainly follows the first-order kinetics between the time intervals of 60–180 min. The characteristics of degraded water were assessed by a TOC analyzer. The value of total inorganic carbon (TIC) in MG before treatment was 90 mg/L and seems to be slightly high when compared to MG after treatment which was found to be 87.65 mg/L and the adsorbent-treated water with a low value of 54.25 mg/L. These results well matched with the characteristics of normal water. The presence of phycocyanin in the degraded water was effectively removed by treating with activated carbon and it was confirmed with fluorescence analysis. These results support that the MG dye degradation was exhibited by phycocyanin extract and bio-mimics the quantum dot photocatalytic activity. [ABSTRACT FROM AUTHOR]

This study deals with the toxicity of the treated solutions of two types of dyes, namely, the anthraquinonic Reactive Bleu 19 dye (RB19) and the bi-azoic Direct Red 227 dye (DR227), which are treated in single and binary mixture systems. The target molecules were removed by the photocatalysis process using ZnO as a catalyst, which was calcined at two temperatures 250 and 420 °C (ZnO250 and ZnO420) prepared in the lab by the one-step calcination method. XRD, TEM, EDX, XPS, FT-IR, BET, RAMAN, and EPR analyses were carried out to characterize the catalyst material. While the phytotoxicity was being conducted using watercress seeds, the cytotoxicity took place using a cell line (raw) and an intestinal cell (caco-2). The XRD analysis showed the partial calcination of ZnO250 and the presence of anhydrous zinc acetate along with the ZnO nanoparticles (NPs). This result was not observed for ZnO420. Despite the complete discoloration (100%) of all the final solutions, ZnO250 exhibited a high cytotoxicity and phytotoxicity against the RB19 dye after the photocatalytic treatment; however, it was not the case of ZnO420 which was selected as an eco-friendly photocatalyst for the degradation of organic dyes based on the results of removal efficiency, cytotoxicity, and phytotoxicity. [ABSTRACT FROM AUTHOR]

Organic nature of dyes and their commercially made products are widely utilized in many industries including paper, cosmetics, pharmaceuticals, photography, petroleum as well as in textile manufacturing. The textile industry being the top most consumer of a large variety of dyes during various unit processes operation generates substantial amount of wastewater; hence, nominated as "Major Polluter of Potable Water". The direct discharge of such effluents into environment poses serious threats to the functioning of biotic communities of natural ecosystems. The detection of these synthetic dyes is considered as relatively easy, however, it is extremely difficult to completely eliminate them from wastewater and freshwater ecosystems. Aromatic chemical structure seems to be the main reason behind low biodegradability of these dyes. Currently, various physiochemical and biological methods are employed for their remediation. Among them, microbial degradation has attracted greater attention due to its sustainability, high efficiency, cost effectiveness, and eco-friendly nature. The current review presents recent advances in biodegradation of industrial dyes towards a sustainable and tangible technological innovative solutions as an alternative to existing conventional physicochemical treatment processes. [ABSTRACT FROM AUTHOR]

Water pollution caused by the discharged insolubility petroleum contaminants and organic compound dyes seriously threatens the natural self-purity capacity of the water body and the survival of aquatic species, so it is imperative to restraint the deterioration of the aquatic environment. In this paper, pathways are propounded for the simultaneous removal of insoluble spilling oil and organic dye contaminants. Particularly, hydrophobic ZnSnO3 after stearic acid modification and Bi2MoO6 photocatalysts are introduced into the cotton fabric substrate through solution dip-coating. The durability of the prepared fabric suffers from the acid–base corrosion, thermal treatment and mechanical wear, while still exhibiting remarkable water-repellent (WCA > 150°) property. Furthermore, the remarkable photocatalytic activity makes it possible for reusable degradation and the primary active species, namely the holes, to be verified by the radicals-capturing experiment. It is worth observing that as-prepared superhydrophobic fabric possesses admirable water-proof property and cycling durability of decomposing toxic water-soluble organic dye, thereby contributing to further realizing the ecological concept of clear waters. [ABSTRACT FROM AUTHOR]

Ruthenium-based metal complex dyes have been employed extensively in dye-sensitized solar cells (DSSCs) as photosensitizers, but the cost and toxicity of metal complexes have promoted the development of metal-free organic dyes. The present investigation deals with the synthesis of hemicyanine and Dicyanoisophorone (DCI) based dyes adopting the D-π-A strategy, and their application on sensitization of nano-crystalline ZnO electrodes by appending the carboxyl (COOH) anchoring group as a pendant on the primary skeleton of dyes. Dyes have been characterized by UV, FTIR, and NMR spectroscopic studies. Absorption maxima (λmax) were found in the region 416-551 nm while emission wavelength (λem) was observed in the range 575-685 nm. Cyclic voltammetry and DFT calculations were used to estimate redox potential and band gap energies of dyes. [ABSTRACT FROM AUTHOR]

Dye-sensitized photoelectrochemical cells represent an appealing solution for artificial photosynthesis, aimed at the conversion of solar light into fuels or commodity chemicals. Extensive efforts have been directed towards the development of photoelectrodes combining semiconductor materials and organic dyes; the use of molecular components allows to tune the absorption and redox properties of the material. Recently, we have reported the use of a class of pentacyclic quinoid organic dyes (KuQuinone) chemisorbed onto semiconducting tin oxide as photoanodes for water oxidation. In this work, we investigate the effect of the SnO2 semiconductor thickness and morphology and of the dye-anchoring group on the photoelectrochemical performance of the electrodes. The optimized materials are mesoporous SnO2 layers with 2.5 μm film thickness combined with a KuQuinone dye with a 3-carboxylpropyl-anchoring chain: these electrodes achieve light-harvesting efficiency of 93% at the maximum absorption wavelength of 533 nm, and photocurrent density J up to 350 μA/cm2 in the photoelectrochemical oxidation of ascorbate, although with a limited incident photon-to-current efficiency of 0.075%. Calculations based on the density functional theory (DFT) support the role of the reduced species of the KuQuinone dye via a proton-coupled electron transfer as the competent species involved in the electron transfer to the tin oxide semiconductor. Finally, a preliminary investigation of the photoelectrodes towards benzyl alcohol oxidation is presented, achieving photocurrent density up to 90 μA/cm2 in acetonitrile in the presence of N-hydroxysuccinimide and pyridine as redox mediator and base, respectively. These results support the possibility of using molecular-based materials in synthetic photoelectrochemistry. [ABSTRACT FROM AUTHOR]

A novel metal–organic framework based on Co(II) ions as nodes {[Co2(bptc)(DMF)2(H2O)]DMF·H2O}n (1) was prepared and structurally characterized via the reaction of a rigid 3,3,5,5-biphenyltetracarboxylate (H4bptc) and Co(NO3)2·6H2O under the solvothermal conditions. The photocatalytic performances for complex 1 toward organic dyes degradation were studied. In the biological section, the treatment activity of the synthetic compound against renal failure patients combined with Staphylococcus aureus biofilm formation was evaluated, the related mechanism of the new compound was explored at the same time. [ABSTRACT FROM AUTHOR]

Organic pigments with non-polar groups are insoluble in water and most organic solvents and therefore require a dispersion process before application. Besides, since there is no affinity between fabrics and pigments, binders must be added to the printing paste, resulting in the stiff hand feel and poor rubbing fastness of printed fabrics. In this paper, a novel polymer colorant (PGMA-NH-X-3B) with high-stability and reactivity was fabricated and it was further applied to binder-free pigment printing of citric acid treated cotton fabric. The structure of PGMA-NH-X-3B was characterized by FT-IR, EDS, XRD, and SEM. The prepared PGMA-NH-X-3B powders can be easily dispersed in water and the dispersion exhibited excellent storage stability with the particle size change of 3.80% for 30 days. FT-IR, XPS, and SEM demonstrated that the covalent bonding and film formation are the dual-action mechanisms for the PGMA-NH-X-3B printed onto the citric acid treated cotton fabric. Finally, the tests of hand feel and fastness showed that PGMA-NH-X-3B printed fabrics had a soft hand feel and good color fastness as compared with the conventional pigment printings with a large number of binders. [ABSTRACT FROM AUTHOR]

This very paper focuses on the preparation of an eco-friendly and efficient photocatalyst aiming to degrade organic dyes in wastewater. The cheap and abundant straws were carbonized to prepare porous carbon pieces in this study. A simple hydrothermal method was employed to prepare the porous carbon/CdS (PC/CdS) composite. CdS nanoparticles were anchored on these porous carbon sheets, forming the PC/CdS composite. The composite was annealed at 300, 400, and 600 °C, respectively, and then these samples were characterized by SEM, TEM, XRD, and FTIR. As an important parameter, the porosities of PC and the PC/CdS were characterized by BET method. Particularly, the photo-electronic response of PC/CdS has been characterized by EIS, PL, and transient photocurrent. It is found that the carrier mobility and shape of PC itself and the annealing process improved the photocatalytic activity, as well as adsorption ability. Those composites were able to thoroughly degrade RhB within 90 min under the irradiation of visible light. What is interesting and quite different from other reports is that there was no conjugated part of RhB left in the solution after photocatalytic degradation. [ABSTRACT FROM AUTHOR]

Two novel dyes 3a and 3b named triphenylamine groups containing donor–acceptor structural units have been explored to be used in dye sensitized solar cells as organic sensitizers. The absorption bands of the dyes were extended up to ~ 550 nm with visible absorption maxima at 408–430 nm and optical band gaps of 2.44–2.47 eV. Compared to the methoxyphenyl-substituted dye, the introduction of triisopropylphenyl group instead of that increased fluorescence quantum yields and exhibited red-shift emission in chloroform. We have investigated the photovoltaic properties of DSSCs based on these metal free organic dyes. It has been found that the power conversion efficiency of DSSCs sensitized with methoxyphenyl based triphenylamine dye is higher than that for sensitized with triisopropylphenyl derivative. [ABSTRACT FROM AUTHOR]

Abstract: CdS nanoparticles (CdS NPs) and CdS nanoslabs (CdS NSs) were synthesized from the single source (SS) and multi-source (MS) precursors, respectively. Our target was to observe any change in morphology by altering the synthetic route. CdS NPs with spherical morphology (0.2-0.5 µm in diameter) were obtained by using the SS precursor route via the formation of a Cd-complex. CdS NSs (100-200 nm in length, 50-100 nm wide and 25-50 nm in thickness) were obtained by using the MS precursors, by direct addition of the ligand to metal salt. Both NPs and NSs were used for the degradation of four different cationic organic dyes viz., malachite green (MG), methylene blue (MB), rhodamine B (RhB) and methyl violet (MV) under visible light. CdS NPs synthesized from SS precursor exhibited higher photocatalytic activity than CdS NSs fabricated via MS precursor due to spherical morphologies (small size of particles increases the surface area) and higher band gap. On the other hand, CdS NSs show sheet or cube like morphologies. The kinetic study proved that the rate constants for the MG, MB, MV, and RhB degradation by CdS NPs (1.65 × 10-2, 1.25 × 10-2, 1.2 × 10-2, and 1.24 × 10-2 min-1, respectively) are higher than those for CdS NSs (1.45 × 10-2, 1.13 × 10-2, 1.05 × 10-2, 1.14 × 10-2 min-1, respectively). The precursors were characterized by 1H and 13C nuclear magnetic resonance. Phase pattern and composition of CdS were confirmed by X-ray diffraction and energy dispersive X-ray spectroscopy. Morphology and size were confirmed by transmission electron microscopy and scanning electron microscopy. [ABSTRACT FROM AUTHOR]

Using cement-based material as a matrix for photocatalytic hybrids is an important development for the large-scale application of photocatalytic technologies. In this work, photocatalytic activity of nanosized hybrids of TiO/SiO (nano-TiO-SiO) for degradation of some organic dyes on cementitious materials was highlighted. For this purpose, an optimal inorganic sol-gel precursor was firstly applied to prepare the composites of nano-TiO-SiO which was characterized by XRD, SEM and UV-Vis. Then, a thin layer was successfully coated on white Portland cement (WPC) blocks using a dipping process in a nano-TiO-SiO solution. The effect of nano-TiO-SiO-coated WPC blocks on photocatalytic decomposition of three dyes, including Malachite green oxalate (MG), Methylene blue (MB) and Methyl orange (MO) were studied under UV irradiation and monitored by chemical oxygen demand tests. The results showed an increase in photocatalytic effects which depends on the structure and pH of the applied cement. [ABSTRACT FROM AUTHOR]

In this research, photoassisted electrochemical degradation of 13 commercial dyes with various chemical structures and substituent groups was investigated using a cathode containing carbon nanotubes (CNTs) and a titanium/ruthenium oxide (Ti/RuO) anode. The inner and outer diameters of the CNTs and their stabilization on carbon paper support were confirmed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. All experiments were carried out in identical operating conditions using a recirculation system under ultraviolet (UV) light irradiation. The dyes with electron-releasing groups (e.g., amino, hydroxyl, and acetamido) were more degraded than those containing electron-withdrawing groups (e.g., sulfo, sulfonyl, and halo) due to inductive and/or resonance effects. Moreover, the obtained results reveal that the degradation process follows pseudo-first-order kinetics, and the degradation efficiency was evaluated as the electrical energy per order. [ABSTRACT FROM AUTHOR]

This study is carried out to design diarylamine-fluorene dyes by incorporating electron‐deficient thiadiazole derivatives. Quantum chemical calculations are performed to study the geometries, electronic structures and absorption spectra of the dyes. Interaction of dyes with TiO2 cluster is also studied. The effects of the electron‐deficient units on the spectra and electrochemical properties have been investigated. Dyes D1–D4 display remarkably enhanced spectral response in the red portion of the solar spectrum as compared with reference compound D0. The newly designed dyes demonstrate desirable energetic and spectroscopic parameters and may lead to efficient metal‐free organic dye sensitizers for DSSCs. [ABSTRACT FROM AUTHOR]

This study reports on a novel chemical route to synthesize new elongated titanates nanostructured hybrid materials by the combination of titanate nanofibers (TNFs) with organic dye molecules. The influence of the sodium/proton replacement on the adsorption and intercalation characteristics of the TNFs materials was analysed. Depending on the sodium/proton content, materials with surface areas in the 21.08-38.90 m/g range were obtained. Due to their molecule size and shape, and anticipating their intercalation between the TiO layers, the cationic molecules chosen for this study were thionine, methylene blue, crystal violet and rhodamine 6G. The sample with the highest sodium content was the best material on up taking dyes from aqueous media. The amount of the immobilized dyes was higher than the one predictable for the formation of a monolayer in an adsorption process. The intercalation of thionine, methylene blue and crystal violet between the TiO layers was accomplished. The characterisation results obtained by adsorption, XRD and FTIR are in agreement with the production of these new hybrid structures, with the organic molecules located within the TiO layers. The results also demonstrate that only the thionine was incorporated in the protonated titanate structure, due to the smaller distance between the layers. The optical characterisation of the prepared materials by DRS also indicates that intercalated and adsorbed dyes have strong influence on the optical properties of the new hybrid materials prepared. [ABSTRACT FROM AUTHOR]

Radical ions of organic dyes are highly reactive species and have been studied for decades by transient absorption spectroscopy and pulse radiolysis experiments in oxygen-depleted solution. Here we show by continuous wave EPR, absorption, and fluorescence experiments that the triplet state of rhodamine dyes can be photoreduced by thiols to form stable radical anions in aqueous solution with a lifetime of up to several hours. Our data demonstrate that reduction of the triplet state and photoinduced oxidation of reactive intermediates by oxygen represents a general mechanism for reversible photoswitching of dyes in aqueous thiol-containing solutions highlighting the key role of molecular oxygen for super-resolution fluorescence imaging. Since cells contain the thiol glutathione at millimolar concentrations and reactive oxygen species are formed as side products our findings are of consequence for live cell fluorescence microscopy. [ABSTRACT FROM AUTHOR]