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Semiconductor coupling is one of the best incredible ways to improve the photo-absorption range from UV to the visible region. Here, we prepared various proportions of titanium dioxide (TiO2) and zinc oxide (ZnO) and thus determined the best ratio suitable for photo-activated applications. Sol–gel synthesis method is used for the preparation of TiO2 and TiO2/ZnO nanoparticles. TiO2/ZnO composites are prepared in ratios 9:1, 8:2 and 7:3, respectively. HR-SEM micrograph reveals the conversion of surface morphology from rod to plate after addition of ZnO. The peak of photoluminescence spectra lies between 451 and 494 nm, which shows the photocatalyst can absorb photons in the visible region. The photocatalytic degradation of the samples was investigated using a model thiazine dye. The light medium used for the degradation is sunlight. UV spectroscopy results obtained from the sample TiO2/ZnO taken in the ratio 8:2 show an enhanced efficiency. The least absorbance was shown clearly with an efficient degradation of 95.11%. Photocatalysis procedure was repeated with the same photocatalyst up to five times, and dye degradation efficiency was not decreased. Durability of TiO2/ZnO paves the way for applications like anti-microbial activity, energy conservation and waste water treatment. [ABSTRACT FROM AUTHOR]

Polymers from renewable resources have been used for a long time in biomedical applications and found an irreplaceable role in some of them. Their uses have been increasing because of their attractive properties, contributing to the improvement of life quality, mainly in drug release systems and in regenerative medicine. Formulations using natural polymer, nano and microscale particles preparation, composites, blends and chemical modification strategies have been used to improve their properties for clinical application. Although many studies have been carried out with these natural polymers, the way to reach the market is long and only very few of them become commercially available. Vegetable cellulose, bacterial cellulose, chitosan, poly(lactic acid) and starch can be found among the most studied polymers for biological applications, some with several derivatives already established in the market, and others with potential for such. In this scenario this work aims to describe the properties and potential of these renewable polymers for biomedical applications, the routes from the bench to the market, and the perspectives for future developments. [ABSTRACT FROM AUTHOR]

A novel core-shell hydrogel bead was fabricated for effective removal of methylene blue dye from aqueous solutions. The core, made of sodium alginate-g-polyacrylamide and attapulgite nanofibers, was cross-linked by Calcium ions (Ca2+). The shell, composed of a chitosan/activated carbon mixture, was then coated onto the core. Fourier transform infrared spectroscopy confirmed the grafting polymerization of acrylamide onto sodium alginate. Scanning electron microscopy images showed the core-shell structure. The core exhibited a high water uptake ratio, facilitating the diffusion of methylene blue into the core. During the diffusion process, the methylene blue was first adsorbed by the shell and then further adsorbed by the core. Adsorption tests showed that the coreshell structure had a larger adsorption capacity than the core alone. The shell effectively enhanced the adsorption capacity to methylene blue compared to the single core. Methylene blue was adsorbed by activated carbon and chitosan in the shell, and the residual methylene blue diffused into the core and was further adsorbed. [ABSTRACT FROM AUTHOR]

The solvatochromic properties of methylene blue (MB) were investigated in neat water, methanol, ethanol, propanol, dioxane and their corresponding aqueous mixtures. The correlation of the empirical solvent polarity scale (ET) values of MB with solvent composition was analysed using the solvent exchange model of Bosch and Roses to explain the preferential solvation of the probe thiazine dye in the binary mixed solvents. Non-linear solvatochromism of MB was observed in aqueous mixtures of methanol, ethanol, propanol and dioxane. The influence of the composition of the solvating shell in preferential solvation of the solute dye was investigated in terms of both solvent-solvent and solute-solvent interactions, and the local mole fraction of each solvent composition in the cybotactic region of the probe was also calculated. Effective mole fraction variation can provide important physicochemical insights into the microscopic and molecular interactions between MB species and solvent components. The results showed that the MB solvation shell was thoroughly saturated with the solvent complex S12 for dioxane more than ethanol and propanol mixtures, and opposite trends for methanol mixtures, whereas the solvent complex S12 could not incorporate into the MB solvation shell. Data from the binary systems were analysed with KAT parameters using a dual model of basicity and polarity. The results showed that the polarity was better suited for spectral shift in aqueous methanol and ethanol solutions, while the basicity was better for aqueous propanol and dioxane solutions. [ABSTRACT FROM AUTHOR]

The emerging field of using titanium dioxide (TiO2)-based photosensitizers for enhancing photocatalytic removal of thiazine dyes such as methylene blue (MB) from water has long been recognized for its exceptional photocatalytic properties, making it an attractive material for environmental remediation and energy conversion. However, its wide bandgap limits its responsiveness to visible light. As such, the utilization of TiO2-based photosensitizers for the removal of thiazine dyes, presents a promising avenue for diverse applications. In addressing the dual challenges of environmental pollution and harnessing sustainable energy sources, this review focuses on the removal of thiazine dyes from water and their subsequent application as photosensitizers for TiO2 materials. Thiazine dyes, ubiquitous in industrial effluents, pose environmental concerns due to their persistence and potential toxicity. Conversely, this innovative approach involves employing TiO2 materials as photocatalysts, utilizing the unique properties of thiazine dyes to enhance light absorption. Studies have shown that beyond the conventional role of thiazine dyes as colorants, they can serve as effective photosensitizers when coupled with TiO2. This tandem not only facilitates the elimination of thiazine dyes, such as MB, from water but also augments the improvement of the photocatalytic performance of TiO2 materials. The synergy between dye sensitizers and TiO2 enhances the overall efficiency of processes like dye degradation and water splitting. Dye sensitizers, acting as light energy absorbers, can efficiently transfer this energy to TiO2, thereby promoting electron transfer and generating reactive oxygen species (ROS). These ROS, in turn, initiate chemical reactions, rendering dye sensitizers valuable in applications such as wastewater treatment, solar energy conversion, and environmental remediation. As such, it is crucial to acknowledge the potential drawbacks associated with thiazine dyes, including toxicity and non-biodegradability. Consequently, careful consideration must be given to thiazine dye application and disposal. Therefore, this review manuscript delves into the comprehensive exploration of TiO2-based photosensitizers, shedding light on their efficacy in various photocatalytic processes for thiazine dye removal.

The binding of the thiazine dye methylene blue (MB) with single-stranded (ss-) polyribonucleotides poly(rA) and poly(rU) was studied using absorption spectroscopy and UV-melting. The binding mechanisms of MB to poly(rA) and poly(rU) were found to differ significantly. The obtained data indicated that the main mode of interaction between MB and ss-poly(rA) and ss-poly(rU) corresponded to semi-intercalation to electrostatic binding, respectively. MB was also found to contribute to the formation of the hybrid duplex poly(rA)–poly(rU). [ABSTRACT FROM AUTHOR]

Plasmas generated over and under the surface of water have immense scope for wastewater remediation due to in situ generation of redox-rich species. Remediation of simulated wastewater using underwater plasma discharge is reported in this paper. During the plasma discharge, an increase in energy coupling from source to discharge channel was noted with an increase in the applied pulsed DC voltage from 5 to 9 kV. Higher energy coupling resulted in elevation of gas temperature and electron temperature. Concentrations of hydroxyl radicals and hydrogen peroxide, estimated spectrochemically in effluent water, also increased with the applied voltage. On the other hand, ozone concentration showed a decreasing trend with increasing applied voltage and the peak ozone density was obtained at the lower end of the applied voltage, i.e., at 5 kV. With higher energy dissipation, a pronounced discharge and, hence, greater emission intensities of ultraviolet radiation, atomic oxygen, and atomic hydrogen were observed in discharge spectra. The oxidative-reductive stress produced by underwater discharge resulted in a degradation efficiency of 75.5 % for methylene blue solution (thiazine dye) corresponding to energy yields of 3.55 g / kWh . Similarly, the degradation efficiency of 81.4 % for methyl orange solution (azo dye) with an energy yield of 4.73 g / kWh was achieved with this discharge. From the considerations of collision theory, activation energies of 67.17 kJ / mol for methylene blue and 75.32 kJ / mol for methyl orange degradation were estimated for the plasma discharge. Fourier-transform infrared spectroscopy was utilized to further reveal the possible effects of plasma therapy on different bonds of the dyes. Additionally, gas chromatography mass spectrometry analyses were used to suggest the possible degradation pathways of the two dyes. Instant dye degradation in flowing samples was compared with contemporary dye degradation results listed in literature to show the effectiveness of the used technique. [ABSTRACT FROM AUTHOR]

Developing CeO2-diatomite composites with highly efficient photocatalytic performance is a practical and low-cost strategy for the removal of abundant contaminants in water and wastewaters. Diatomite (D) was modified by acid treatment to obtain a more porous structure. CeO2-diatomite composites were prepared in two different mass ratios of D to CeO2 of 1:1 and 1:2 via a facile precipitation method. The changes in structural, morphological, optical, and thermal properties of CeO2-diatomite composites were characterized by FTIR, XRD, ESEM-EDAX, BET surface area, TGA, PL, Raman spectroscopy, and zeta potential techniques. ESEM images presented the morphological differences of CeO2-diatomite composites, reflecting the effect of modification as a more folded sheet form morphology and higher BET surface area. XRD analysis revealed the fluorite-type structure of CeO2 particles in composites. Photocatalytic activities were investigated by following the degradation of methylene blue (MB) as a thiazine dye model under UVA light irradiation. CeO2-diatomite composites exhibited irradiation time- and dose-dependent remarkable photocatalytic efficiencies, whereas composite type inconsistent variations were also noticed. The attained performance of the CeO2-diatomite composites could strongly imply a favorable application prospect in the photocatalysis field. [ABSTRACT FROM AUTHOR]

Theoretical modeling of changes in the vibronic absorption and fluorescence spectra in the molecules of two dyes of the thiazine series – methylene blue and methylene green – during the transition from an acidic to an alkaline medium has been carried out by the time dependent density functional theory (TDDFT) method. It is shown that the introduction of the NO2 group leads to more resolved vibronic spectra in the case of low pH values and to the opposite effect at high pH values. This effect can be explained by the intramolecular interaction of functional groups that make up the corresponding molecules. [ABSTRACT FROM AUTHOR]

Introduction: In the field of pediatric dentistry, an urge to adopt a more comfortable, minimally invasive, and stressless technique for caries removal became a must. Coronavirus disease-2019 outbreak necessitates a paradigm change in the global health care protocols, requiring alternative, nonaerosol generating approaches. This study aimed to measure and compare the influence of two methods of caries removal, namely, Brix3000 and CeraBur, on the microleakage of glass hybrid restorative material. Materials and Methods: Thirty human primary molar teeth with accessible occluso-gingival carious cavitation were randomly allocated into CeraBur and Brix3000 groups. After selective caries excavation, samples were restored with Equia Forte HT, thermocycled, dipped in thiazine dye, washed, and sectioned through the restoration center. Then microleakage was measured using a stereomicroscope (30× magnification) at both occlusal and gingival margins. Results: No statistically significant difference was found between the two methods of caries removal (CeraBur and Brix3000) at both occlusal (P = 1.000) and gingival margins (P = 0.612). Conclusions: Brix3000 caries removing gel did not negatively affect the microleakage of Equia Forte HT compared to the CeraBur and hence can be used alternatively to the conventional drilling methods. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sulfite-based catalyst/photoenergy-free process facilitated thiazine dye destruction. • Electron donating capability of sulfite promoted reaction kinetics via bimolecular collisions. • Sulfite mediated oxysulfur radicals and reductive spicies possed excellent activity and stability. • The coupling photocatalysis enhanced pollutants mineralization. Sulfite-based advanced reduction processes have been extensively studied as a purposeful option of wastewater treatment, while their direct chain reaction mechanisms involved reductive destruction of textile dye are still unclear. Here, we reported that sulfite source can selectively destructed cationic dyes of thiazines without photoenergy and catalysts activation in neutral pH. The series of electrochemical experiments (e.g., galvanic oxidation, chronoamperometry measurements and cyclic voltammograms) showed that sulfite attacks phenazine dye of methylene blue via electrons transfer to form the primary electron-donor radical cation species of sulfite radical, followed by the auto-catalytic decontamination concurrently with hydrated electrons and oxysulfur species from radical chain reactions under aerobic conditions. Based on radical quenching and electron paramagnetic resonance, the underlying mechanism of reaction kinetics and activation pathway can be expanded to other common thiazine dyes (Azure II, Azure A and thionine) and even capable for removing co-existing azo dye of methyl orange and their raw production material of aniline in textile effluents. The selective bimolecular collisions system between thiazine and sulfite triggered the spontaneous radical formation without clear deactivation and water matrix affect, which is furthered to provide new ideas for hybrid treatment construction with respect to sustainable management of textile dye wastewater at industrial applications prospect. [ABSTRACT FROM AUTHOR]

[Display omitted] • Azure dyes were studied as inhibitor against the corrosion of mild steel in 1 N HCl. • PDP study reveals that the studied inhibitor acts as a cathodic-type inhibitor. • The inhibitor follows the Langmuir, Temkin, and El-Awady Adsorption Isotherms. • Adsorption of inhibitor on the mild Steel surface is observed by AFM. • Theoretical studies via DFT were performed to understand the inhibition mechanism. Organic derivatives and dyes represent a promising and efficient class of corrosion inhibitors, demonstrating considerable potential in fulfilling the criteria for utilization as corrosion inhibitors. In the present study, the anti-corrosive impact of some Thiazines dyes: Azure A (D-1), Azure B (D-2) and Azure C (D-3), has shown a decelerative effect on mild steel in 1 N HCl environment and was investigated using experimental {Weight loss (WL), Electrochemical method and Atomic Force Microscope (AFM)} and theoretical {Density Functional Theory (DFT)} studies. It was found to have an efficiency in the order of D-3 (98.09 %) > D-1 (89.94 %) > D-2 (76.44 %) at elevated temperatures (338 K for 100 ppm concentration) deliberated through WL method. D-3 had greater stability than D-1 and D-2 at elevated temperatures which is indicative in the obtained experimental data. As examined via electrochemical and WL analysis, the cathodic type of inhibition mechanism and adsorption isotherm viz. Langmuir, Temkin and El-Awady were followed by all three dyes. Results of surface analysis and thickness of deposited layer by AFM agreed with other experimental outputs. A theoretical study for these thiazine dyes was probed employing DFT that illustrated the formation of a complex among the dyes and mild steel. The corrosion inhibition efficacy of dyes, as deduced from both experimental and theoretical data, aligns cohesively, thereby establishing a comparatively durable monolayer at the mild steel/medium interface, preventing steel deterioration in a specified range of temperatures. [ABSTRACT FROM AUTHOR]

In this study, nanoiron and nanoiron+Au particles were synthesised using aqueous Aegle marmelos extract using a facile and one-pot approach. Lower size non-magnetic nanoiron (~34 nm) and nanoiron (~34 nm) +Au particles (1 to 1.5 µm) were produced from the same medium individually. Nanoparticles suspension behaviour and structural characterisations were carried out by UV-Vis spectroscopy, electron microscopy and by X-ray diffraction techniques. Primarily, for synthesis, a simple bioreduction approach generated amorphous nanoiron particles, which on annealing produced magnetic maghemite, γ-Fe2O3 type nanoparticles with sizes 100 to 1000 nm. Posteriorly, the bioreduction process also produces nanoiron+Au particles and can be used for multifunctional applications. As a model application, catalytic application of the as-prepared nanoiron and nanoiron+Au particles towards methylene blue, a thiazine dye degradation is investigated and found to be effective within 20 min. Langmuir-Hinshelwood kinetic model was exploited to know the degradation behaviour, and the model was found to be fit based on R2 values with the observed experimental data. We suggest that the formed highly stable nanoiron particles with in situ stabilisation offer benefits like consistency, environmental friendliness and suits well for large-scale applicability. [ABSTRACT FROM AUTHOR]

A comparative investigation of the reaction of the bisbenzimidazole compound Hoechst 33258 and the thiazine dye methylene blue (MB) with bovine serum albumin (BSA) was carried out by spectroscopic methods. Denaturation curves and absorption and differential absorption spectra of the protein-ligand complexes were obtained. It was shown that the denaturation temperature of the albumin complexes of BSA with Hoechst 33258 decreases with increase of the ligand/protein concentration ratio whereas in the case of MB the denaturation temperature increases. Changes in the absorption spectra and differential absorption spectra of the complexes of the ligands with albumin resulting from combination of these specific ligands with the protein were observed. It is supposed that during interaction of Hoechst 33258 with BSA some loosening of the protein compact structure occurs as a result of partial loss of helicity in the α structures, whereas in the case of MB the degree of packing in the spatial structure of the protein is increased. [ABSTRACT FROM AUTHOR]

Organic dyes used in the food and textile industries are the primary sources of environmental contamination due to their high toxicity and nonbiodegradability. This paper describes the synthesis of cellulose nanocrystals/zinc oxide (CNC/ZnO) nanocomposite via the solgel method. Various characterization techniques such as FTIR spectroscopy, UV-Vis spectroscopy, and FESEM-EDX analysis were done. FTIR and UV-Vis analyses initially confirmed the formation of CNC/ZnO nanocomposites. FESEM-EDX showed a fiber-like structure with agglomerated particles on the CNC-ZnO image, suggesting the functionalization of ZnO nanoparticles onto the CNC. The photocatalytic potential of the CNC/ZnO nanocomposite was then evaluated by degrading 10 ppm thiazine dye (methylene blue) solution. The solution was irradiated with UV and visible light at an ambient temperature. The degradation was monitored at different time intervals using a UV spectrophotometer to measure the absorbance value intermittently. Results on the photocatalytic activity indicated that the synthesized CNC/ZnO nanocomposite showed faster degradation under UV light irradiation than the visible light, with an efficiency of 96.11% and 85.60%, respectively, after 180 mins of light irradiation. Further, the results suggest that the synthesized CNC/ZnO nanocomposite showed great promise as a sustainable material for the degradation of organic contaminants in an aqueous solution. [ABSTRACT FROM AUTHOR]

Methylene blue (MB) is a cationic thiazine dye, widely used as a biological stain and chemical indicator. Growing evidence have revealed that MB functions to restore abnormal vasodilation and notably it is implicated even in pain relief. Physicians began to inject MB into degenerated disks to relieve pain in patients with chronic discogenic low back pain (CDLBP), and some of them achieved remarkable outcomes. For osteoarthritis and colitis, MB abates inflammation by suppressing nitric oxide production, and ultimately relieves pain. However, despite this clinical efficacy, MB has not attracted much public attention in terms of pain relief. Accordingly, this review focuses on how MB lessens pain, noting three major actions of this dye: anti-inflammation, sodium current reduction, and denervation. Moreover, we showed controversies over the efficacy of MB on CDLBP and raised also toxicity issues to look into the limitation of MB application. This analysis is the first attempt to illustrate its analgesic effects, which may offer a novel insight into MB as a pain-relief dye. [ABSTRACT FROM AUTHOR]

Methylene blue (MB) is a blue cationic thiazine dye and currently used in different medical settings. Notably, there have been several attempts to introduce MB for attenuating pain in the last decade. Some clinical studies reported remarkable results, which, however, have been much debated. In addition, accumulating evidence have revealed that MB diminishes voltage-gated sodium channel currents. Accordingly, in the present study, we conducted in vivo experiments, including in vivo single nerve recording and behavioral test, to investigate whether MB dampens neural firing rates and ultimately contributes to pain relief. As a result, neural firing rates significantly decreased and finally converged to zero after MB administration. This event lasted longer than that of lidocaine and was dose-dependently modulated. Furthermore, there was a marked improvement in pain behaviors. The withdrawal threshold and latency of hind paws significantly rose post-MB administration. Therefore, these results demonstrate that MB lessens pain by significantly weakening neural excitability, which implies a strong possibility that this dye may be developed as a pain-relieving medication in the future. This is the first in vivo study to elucidate the effect of MB on nerves and pain relief. • Methylene blue, a dye, attenuated significantly neural firing rates compared to lidocaine. • The dye also markedly delayed hind paw withdrawal reflexes elicited by mechanical and thermal stimuli. • Methylene blue lessens pain by dampening neural excitability. • Methylene blue may be developed as a therapeutic agent for pain patients. [ABSTRACT FROM AUTHOR]

Developing microdevices capable of performing multifunctional sensing measurements is of grand importance for various applications including the study of diseases, rapid biomolecular detection, and drug discovery. In this paper, we demonstrate a compact electro-optical multimodal microprobe with a small footprint (∼10 µm diameter), low electrical impedance (∼ 10 k Ω at 1 kHz), and high optical spatial resolution. The electrical channel is validated by selectively detecting dopamine and serotonin via electrochemistry with a limit of detection of 800 nM and 1.2 µM, respectively. The optical channel is then combined with the adjacent electrical channel to perform localized spectroelectrochemical probing of electrochromic materials including conductive polymers such as poly(3,4-ethylenedioxythiophene) and thiazine dyes such as methylene blue. Due to the size of the probe, dimensional and mechanical tunability, and minimal interference between the co-localized electrical and optical channels, this device architecture shows great promise for in vivo sensing and in situ biomolecular measurements. [Display omitted] • Engineer small footprint, multimodal fibers with a low electrical impedance channel surrounding a central optical channel. • Demonstrate selective electrical detection of neurotransmitters with a thin metal-polymer fiber optic cladding layer. • Perform local spectroelectrochemistry probing with high sensitivity on electrochromic materials. [ABSTRACT FROM AUTHOR]

• Free-standing acoustic levitator technique for organic dye self-aggregation process. • Methylene blue (MB) droplet aggregation via acoustic standing waves. • MB dimerization reactions monitored by in situ spectroscopic techniques. • H- and J-aggregation in different solvent environments was studied by DFT studies. In this work, we explored the in-situ reaction modeling of the molecular self-aggregation of methylene blue (MB), which is a cationic thiazine dye, in different solvents via a container-less acoustic levitator by floating of a single droplet. Our in-situ spectroscopic study revealed that the dimer essentially has a sandwich structural geometry with a deviation from parallel stacking and horizontal arrangements in the molecular planes. The real time conversion of the monomer in MB into a dimer and their dynamics in water and ethanol media were monitored using a free-standing acoustic levitator droplet system. The absorption spectra revealed changes in the two resolved peaks (monomer and dimer) and orderliness when water and ethanol were used as the media. Interestingly, the enhancement in the dimerization of MB could be attributed to droplet evaporation, which is difficult to observe in typical reactor containers. Moreover, acidic protonation resulted in a change in the aggregation orientation direction of the MB molecules, forming an unusual J-aggregation. Theoretical DFT calculations revealed that MB underwent typical H-aggregation and J-aggregation in the different solvent environments, and their orientations well matched the spectroscopic data. [ABSTRACT FROM AUTHOR]

Abstract A Co(II) coordination polymer {[Co 3 (L) 2 (tib) 2 (H 2 O) 2 ]·10H 2 O·2HO·2O)} n [L = 2, 6-di(4-carboxylphenyl)pyridine-4-carboxylic, tib = 1, 3, 5-tris(1-imidazolyl)benzene)], was synthesized under the condition of solvothermal and characterized by X-ray single-crystal diffraction, elemental analysis, IR spectra and thermogravimetric (TG) analysis. X-ray single-crystal diffraction analysis exhibits that the complex possesses a 4-nodal (3, 3, 4)-connected 3D topology framework with the Schläfli symbol (7·8·9) (7·82·92) (74·92) (7·8·9). Moreover, the adsorptive removal test were performed of the complex for methylene blue (MB) from wastewater in terms of kinetics and isothermal adsorption. All results showed significant adsorption capacity of the complex for MB. Highlights • A Co(II) coordination polymer {[Co 3 (L) 2 (tib) 2 (H 2 O) 2 ]·10H 2 O·2HO·2O)} n [L = 2, 6-di(4-carboxylphenyl)pyridine-4-carboxylic, tib = 1, 3, 5-tris(1-imidazolyl)benzene)], was synthesized under the condition of solvothermal. • X-ray single-crystal diffraction analysis exhibits that the complex possesses a 4-nodal (3, 3, 4)-connected 3D topology framework with the Schläfli symbol (7·8·9) (7·82·92) (74·92) (7·8·9). • Compared to reported Cu-HKUST-1, k 1 (complex 1) > k 1 (Cu-HKUST-1), q e,exp (complex 1) > q e,exp (Cu-HKUST-1), it fully indicates that the adsorption effect of complexes 1 on MB is stronger than that of Cu-HKUST-1. [ABSTRACT FROM AUTHOR]

The hybrid multilevel approach based on molecular dynamics, quantum mechanics, and statistical theory has been applied to profiles of electronic absorption bands of a number of thiazine dyes (phenothiazine, methylene blue, and methylene green), whose photochemical and biological properties depend on the external medium. The effect of single fragments of the methylene green (MG) molecule on its spectral-luminescent properties is studied. The most preferred geometry for the MG molecule is identified, and its relations with the spectral properties and the solvent nature are established. The energies of the electron states are calculated, and their nature is revealed. The electrostatic potential is analyzed, and the places of the most probable interaction of the molecule with the medium are found. Conclusions on the mechanism of forming the MG absorption spectrum are made based on the observations and calculations performed within the framework of the present work. It is established that the formation of the N-H bonds leads to the formation of an inactive lower excited singlet state and delocalization of the electron charge upon excitation. The position of the maximum of the long-wavelength absorption band of the MG correlates with the donor number of solvents in the series acetonitrile < water < ethanol < isopropanol < dimethyl sulfoxide. The position of the MG electron transition in the region of 630 nm is determined by the interaction of nitrogen and sulfur atoms of the central ring rather than by the increased number of substituents in the structure of the molecule. [ABSTRACT FROM AUTHOR]

In the present research the dye removal in an experimental subsurface wetland was evaluated. First, the calibration curve of the methylene blue was obtained to evaluate the behavior of the removal of this dye in the wetland, obtaining high removal efficiencies of dye and effluent concentrations below the detection limit of the method. Subsequently, the characterization of the effluent wastewater of "Juan Pedro Carbó Serviá" Factory belonging to the Company of "Confecciones Fénix" was carried out, obtaining that these wastewater does not conform to the Cuban regulation standards for the values of pH and Chemical Oxygen Demand. Finally, the purification of this wastewater in the experimental wetland was evaluated, where an effluent conforms to the Cuban standard of discharge and removal efficiencies of more than 90% were obtained. [ABSTRACT FROM AUTHOR]

Sheep manure biochar (SMB500), rabbit faeces biochar (RFB500) and pig manure biochar (PMB500) prepared by controlled thermal decomposition at 500 °C were used to adsorb methylene blue (MB) in water. Elemental analysis, BET and SEM results showed that the specific surface area, total pore volume and average pore diameter of SMB500 were 7.59, 4.20 and 1.16 times greater than those of RFB500, which were also 12.02, 6.88 and 1.37 times greater than those of PMB500, respectively. SMB500 had stronger stability and aromaticity. When the initial concentration of MB was 50 mg L−1 and pH was 11, adsorption achieved equilibrium at approximately 210 min. The adsorption followed pseudo-second-order kinetics (R2 > 0.96), indicating that liquid film diffusion, surface adsorption and intraparticle diffusion all contributed to the adsorption rate. The results of isothermal adsorption showed that the adsorption performance of SMB500 was more consistent with a Freundlich model, whereas the performance of RFB500 and PMB500 was more consistent with a Langmuir model with a maximum adsorption capacity of 53.68 to 238.31 mg g−1. Thermodynamic and FTIR studies showed that the adsorption of MB on SMB500, RFB500 and PMB500 was spontaneous and endothermic, and hydrogen bonds and π-π bonds were closely related to the adsorption process. The results of regeneration show that the optimal number of cycles for SMB500, RFB500 and PMB500 are 8, 5 and 3, respectively. [ABSTRACT FROM AUTHOR]

In this paper, the roles of intermolecular interactions and probability of aggregates formation on the nonlinear optical properties of thiazine dyes are investigated. Our results show that saturable and reverse saturable absorption properties of these dyes depend strongly on the molecular surrounding media characteristics and their collective properties that tend to form aggregated species at high concentrations. Depending on molecular surrounding media characteristics, by increasing the concentration of dye solutions and formation of aggregates, the strong solute-solute interactions can modify the nonlinear responses of dye solutions. The experimental results indicate that by increasing the contribution of J aggregates, the third-order nonlinear responses of binary mixtures of water and ethanol are increased at room temperature. Therefore, the intermolecular interactions and the presence of J aggregates can be considered as simple techniques for improving the nonlinear responses of selected ionic dyes. [ABSTRACT FROM AUTHOR]

Abstract: Reactive dyes are extremely toxic and harmful to the environment even present at very low concentration. In this study, sodium alginate based reusable hydrogels was prepared for the removal of methylene blue from waste water. pH-tunable hydrogels was prepared by the introduction of ionic pendant functionalities on sodium alginate (SA) by the utilization of ethylene glycol and acrylic acid through condensation followed by free radical polymerization. The structure, formation and thermal stability of hydrogel was identified by Fourier transform infra red spectroscopy and thermogravimetric analysis respectively. Swelling nature at different pH ranges and the humidity contents of both dried and dye adsorbed hydrogels was investigated. The morphology of the dry and dye adsorbed hydrogel was also studied using scanning electron microscopy. The swelling studies infer that pronounced swelling obtained at higher pH than at lower pH. The surface morphology of plain hydrogel before and after adsorption of methylene blue (MB) was examined by SEA analysis. The adsorption tendency of the SEA hydrogel in MB was steadily investigated at different pH, contact time, concentration dye and adsorbent dosage. All prepared hydrogels were performed well in the removal of MB from waste water up to 80-98%. Recycling of hydrogels has a vital role for waste water treatment and it can be done by desorption studies which shows that 0.1 N HCl revealed higher elution efficiency i.e. 90.00%. Furthermore, adsorption-desorption studies suggested that SA based hydrogels contributes to enhance the removal efficacy, which renders the hydrogels well-designed for the efficient removal of cationic dyes (MB). However, polyol based hydrogels have been chosen for an adsorbent because of low-cost, ecofriendly, biocompatible and efficient biosorbents.Graphical Abstract: [ABSTRACT FROM AUTHOR]

Feasible method of quantitative determination of anionic polymers in aqueous solutions was described using poly(styrene sulfonate) and poly(acrylate) sodium salts as an example. The method consists in absorbance measurements while titrating with thiazine dye. Volume of dye solution needed to attain specified value of absorbance is linearly dependent on polymer concentration. Optimal wavelengths are 666 nm and 640 nm for Methylene Blue dye and Toluidine Blue dye, respectively. Calibration plots are straight lines (r2 > 0.99) ensuring good accuracy of the method developed. Range of measurable concentrations is dependent on chosen value of end-point absorbance. [ABSTRACT FROM AUTHOR]

In recent years, there has been a growing concern about some substances in the aquatic environment such as methylene blue dye (MB) and 17α-ethynylestradiol (EE2) hormone, mainly from waste textile and pharmaceutical industries, respectively. This waste, which is not effectively treated, generates large amounts of contaminated effluents. Textile industries, which use dyes mainly in their dyeing and finishing processes, generate a lot of effluent contamination by dyes. The 17α-ethynylestradiol hormone which is used in different contraceptive pills and in hormone replacement therapy, is the main substance found in the aquatic environment because of its high resistance to biodegradation. It is known that conventional water treatment processes, which involve the steps of coagulation, flocculation and sedimentation among others, have been reported to be ineffective in the removal of dyes and hormones. The heterogeneous photocatalysis has attracted great interest from many research groups around the world due to its potential application as a pollutant degradation method. For this purpose, the present work evaluated the performance of MnO2/In2O3 thin films in the degradation process of the blue methylene and 17α-ethynylestradiol in aqueous solutions. The degradation processes were monitored by UV-Vis spectroscopy and HPLC chromatography. From these analyzes, the concentration of the solutions was evaluated and it was possible to infer that the MnO2/In2O3 thin films significantly promoted a degradation of 89% of 17α-ethynylestradiol, however, the degradation of the methylene blue was not efficient. [ABSTRACT FROM AUTHOR]

We report the synthesis of two hierarchical organic polymeric networks for extremely efficient visible light and natural sunlight induced degradation of versatile wastewater organic contaminants under different simulated physical conditions following two distinct mechanistic protocols concomitantly. Tailored synthesis of the polymers by effective utilization of high-dilution-technique leads to extremely low density and hence high dispersibility of the networks featuring impressive surface area and gas adsorption abilities. UV–vis absorption spectra of both composites showed a significant coverage of the natural solar irradiance spectrum. A synthetic control over energy-state potentials allowed the materials to demonstrate an unprecedented dye pollutant degradation capability following two mechanisms, the conventional catalyst sensitized pathway, and a substrate-sensitized secondary pathway, simultaneously. Furthermore, the catalyst exhibited a unique time-dependent, sequential, in-situ alteration in substrate selectivity when subjected to a mixed-component pollutant probe. The photocatalytic ability retained essentially unaltered at outdoor condition under natural sunlight illumination as well as after five successive iterations. This work provides an experimental proof of the concept that strategic synthesis can be employed to control the physical and chemical properties of polymeric networks including their energy-states to achieve novel photo-responsive behaviour, and utilize them as green, sustainable environmentally benign and industrially viable heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

The Co 3 O 4 /g-C 3 N 4 Z-scheme system is constructed by decoration of mesoporous Co 3 O 4 nanospheres assembled by monocrystal nanodots on the surface of g-C 3 N 4 , which dramatically improves the photocatalytic activity for degrading tetracycline hydrochloride (TC) compared with single g-C 3 N 4 . The microstructure investigations evidence the mesoporous structure and enlarged specific surface area of Co 3 O 4 /g-C 3 N 4 Z-scheme system, which implies the increase of surface active sites and adsorption ability for reactant molecules. Moreover, by virtue of analyzing physical and photoelectrochemical properties, it evidences that the decoration effect of mesoporous Co 3 O 4 nanospheres on the surface of g-C 3 N 4 obviously improves the transfer and separation efficiency of charge carriers between two phase interfaces and broadens light harvest range. These important factors are beneficial to enhancing photocatalytic activity of Co 3 O 4 /g-C 3 N 4 Z-scheme system. In addition, the photocatalityc reaction mechanism is also revealed in depth. [ABSTRACT FROM AUTHOR]

Spectral, kinetic, and nonlinear optical regularities that demonstrate the exchange of electronic excitations between the components of hybrid associates of Ag2S colloid quantum dots (1.7-1.8 nm) in gelatin with molecules of thiazine dyes (Ds) are found. When the IR luminescence of Ag2S quantum dots (QDs) is excited by radiation from the thionine absorption region, its enhancement due to nonradiative resonant energy transfer is observed. The association with methylene-blue molecules blocked the IR luminescence of Ag2S QDs upon its excitation by radiation from the absorption region of the dye due to the transfer of charge carriers. It is demonstrated that the hybrid association of thionine molecules and Ag2S QDs adversely affects the nonlinear optical properties of the latter, which manifests itself in inverse saturated absorption by the action of 10-ns second-harmonic pulses (532 nm) of a Nd3+:YAG laser. For the associates of Ag2S QDs with methylene-blue molecules, the radiation focusing caused by the transfer of charge carriers from the dye and the change in the population of small traps in nanocrystals is found. It is concluded that the direction of the transfer of electronic excitations and the photophysical processes in these objects are determined by the mutual arrangement of the HOMO-LUMO levels of the dye with respect to the levels of dimensional quantization of the Ag2S QDs. [ABSTRACT FROM AUTHOR]

Synthetic dyes are among the most important environmental pollutants in wastewaters. Consequently, elimination of the synthetic dyes from wastewaters using non-toxic materials and eco-friendly technologies has been of considerable interests. In this study, magnetically separable Ti-doped γ-Fe 2 O 3 photocatalysts were synthesized for the removal of methylene blue (MB) from a dye-contaminated aqueous solution (as a model of dye-polluted wastewaters). Compared to the pristine γ-Fe 2 O 3 , the 1.78 v% Ti-doped γ-Fe 2 O 3 significantly increased the adsorption of MB by 57% in the dark condition as a result of the improved BET surface area in this photocatalyst. Moreover, the contact time required for the photocatalytic degradation of MB by the 1.78 v% Ti-doped γ-Fe 2 O 3 decreased due to the higher concentration of charge carriers in this photocatalyst than that of the pristine γ-Fe 2 O 3 . The effect of different experimental parameters on the adsorption property and photocatalytic activity of the 1.78 v% Ti-doped γ-Fe 2 O 3 photocatalyst showed that the solution pH had a remarkable influence on the removal performance of this photocatalyst. Surface treatment of the 1.78 v% Ti-doped γ-Fe 2 O 3 with sodium dodecyl sulfate (SDS) resulted in the formation of a negatively charged Ti-doped γ-Fe 2 O 3 /SDS photocatalyst, which showed a higher tendency for the adsorption and removal of MB than the untreated photocatalyst. Moreover, the MB removal efficiency of this photocatalyst was among the best performances that have been reported for the γ-Fe 2 O 3 -based photocatalysts. The synthesized photocatalysts were characterized by various techniques, and a plausible mechanism for the removal of MB from aqueous solutions by the Ti-doped γ-Fe 2 O 3 /SDS photocatalyst was purposed. [ABSTRACT FROM AUTHOR]

Nonlinear optical materials play important roles in optics and photonics. In order to improve the performance of these materials, in this paper, we tried to find effective methods for controlling the nonlinear responses of thiazine dyes. Our experimental results indicate that molecular linear properties, media polarity, concentration and excitation beam properties with different contributions play significant roles on the saturable and reverse saturable absorption characteristics of thiazine dyes. In real, competition between these effective parameters leads to appearance of various third order nonlinear responses. Although by excitation wavelengths near the absorption peaks and at high powers, dye molecules tend to indicate reverse saturable absorption characteristics in polar protic solvents by increasing the concentration, saturable absorption characteristics were observed in polar aprotic solvents. Furthermore, the samples displayed the same behaviors in different solvent media at low powers and for excitation wavelengths far from absorption peaks. Therefore, by controlling the nonlinear responses of thiazine dyes, these materials can indicate both saturable and reverse saturable absorption characteristics that increase their applications in optics and photonics devices. [ABSTRACT FROM AUTHOR]

Abstract: The thiazine dye methylene blue is widely used as a disinfectant and antidote in veterinary medicine. Here, we compared transcriptome differences in the liver of Anguilla japonica exposed to methylene blue using Illumina RNA sequencing technology. A total of 75,953,174 and 86,499,866 clean reads with an average length of 126 bp from control and treatment groups respectively. A total of 148,238 transcripts were assembled, with 62,152 components were assembled. Overall, 416,991 unigenes were checked against the National Center of Biotechnology Information, Non‐redundant, Cluster of Orthologous Groups (COG), and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. Of these, 18,541 genes were judged to be differently expressed. The gene ontology (GO) terms “molecular function” and “biological process” were the most enriched in protein binding, followed by “ATP binding and regulation of transcription,” and “DNA‐dependent.” KEGG pathway analysis revealed significant enrichment of N‐glycan biosynthesis and the citrate cycle. This study determined that unigenes related to transmembrane transport and drug metabolism in A. japonica were differentially expressed following exposure to methylene blue. These findings can shed insight into the mechanism of methylene blue metabolism in this economically important species. [ABSTRACT FROM AUTHOR]

In this paper, solvent effects on the linear and nonlinear optical responses of thiazine dyes were investigated. Spectroscopic and open aperture Z-scan techniques were used for studying linear and nonlinear responses of azure A and methylene blue dyes. The experimental results show that linear and nonlinear optical properties of used dyes depend highly on the molecular structure and their surrounding media characteristics. The calculated contribution of various media-induced interactions indicate that solvent hydrogen bond acceptor and solvent dipolarity and polarizability abilities have significant effects on the linear and nonlinear absorption characteristics of thiazine dyes. Moreover, by transition of the linear optics domain to nonlinear optics, similar resonance structures were obtained for thiazine dyes. So, the spectroscopic technique can be considered as a simple method for prediction of dominant resonance structures and effective solvent polarity parameters on the third-order nonlinear properties of azure A and methylene blue dyes. [ABSTRACT FROM AUTHOR]

Polydopamine-modified granule organo-attapulgite adsorbent (PDA-GOAT) was facilely prepared via a dip-coating approach. The samples were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Surface area and pore size were calculated from the Brunauer-Emmett-Teller method by N2 adsorption-desorption isotherm. The adsorption behaviour of methylene blue (MB) onto PDA-GOAT was systematically investigated. The experimental data revealed that the adsorption process fitted well with the pseudo-second-order kinetics equation and the adsorption isotherm fitted better with the Langmuir model. Thermodynamic analyses illustrated that MB adsorption onto PDA-GOAT was a physisorption endothermic process. Importantly, PDA-GOAT can be regenerated by NaBH4 aqueous solution. The obtained results prove that PDA-GOAT can be a superior reusable adsorbent for the removal of MB from effluent. [ABSTRACT FROM AUTHOR]

Manganese peroxidase (MnP) is associated with lignin degradation and is thus relevant to lignocellulosic-utilization technologies. Technological applications require reaction mixture optimization. A surrogate substrate can facilitate this if its susceptibility to degradation is easily monitored and mirrors that of lignin. The dye methylene blue (MB) was evaluated in these respects as a surrogate substrate by testing its reactivity in reaction mixtures containing relevant redox mediators (dicarboxylic acids, fatty acids). Relative rates of MB degradation were compared to available literature reports of lignin degradation under similar conditions, and suggest that MB can be a useful lignin surrogate in MnP systems. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate, in vitro, the bactericidal effect of AmPDT on Staphylococcus aureus (ATCC 25923) using different concentrations (100, 50, 25, 12.5 and 6.25 μg/mL) of phenothiazine compound combined with LED light (λ632 ± 2 nm) using varied energy densities (12, 9.6, 7.2, 4.8 and 2.4 J/cm 2 ). The experiments were carried out in triplicate and the samples were divided into groups: Control, Irradiated (treated only with light at different energy densities), Photosensitizer (treated only in the presence of the dye), AmPDT (treatment with light associated with dye). Counts of the colony forming units and the data obtained were statistically analyzed (ANOVA, Tukey's test, p < 0.05). The results showed no difference between irradiated and Control groups. However, using the photosensitizer alone caused significant increased cytotoxicity and consequent reduction on the CFU counts (12.5 μg/mL (p < 0.001), 25 μg/mL, 50 μg/mL and 100 μg/mL (p < 0.0001). When AmPDT was used significant inhibition above 70% were detected for all concentrations of the photosensitize (p < 0.0001) except for 6.25 μg/mL. The results indicate a dose-response dependent when the photosensitizer is used alone but not for the sole use of the light is used. It is concluded that, a single application of AmPDT, using energy density of 12 J/cm 2 associated either to 12.5 (81.52%) or 25 μg/mL (91.57%) resulted in higher in vitro inhibition of S. aureus . [ABSTRACT FROM AUTHOR]

Nanoceria (CeO 2 ) and a new β-cyclodextrin coated CeO 2 nanocomposite (β-CD-CeO 2 ) materials were prepared by using a combination of precipitation and sol-gel method for efficient degradation of organic dyes from aqueous solutions at room temperature. The prepared catalysts were characterized by using various analytical techniques such as XRD, FT-IR, Pyridine adsorbed FT-IR, Raman spectroscopy, FESEM, TEM and HRTEM. The XRD study suggests the formation of nanocrystalline materials which is further confirmed from the TEM photographs. The presence of oxygen vacancies and lattice defects of the samples were confirmed by Raman analysis. The thermal stability of the prepared catalysts was tested by TGA measurements. UV–Vis analyses were performed to find out the band gap energy and absorbance in the solid state. The β-CD-CeO 2 has the particle diameter of 14 ± 2 nm with band gap of 4.93 eV. The degradation of the methylene blue (MB) was performed by using the prepared catalysts at room temperature in the presence of H 2 O 2 without light irradiation. The process of degradation produces LMB sulfone with m / z = 317 amu, which further lost one or both of its dimethylamine groups to produce substances with m / z = 273 amu and m / z = 229 amu. It was observed that β-CD-CeO 2 efficiently degrades the MB solution completely within 1 h whereas CeO 2 degrades the solution partially giving a higher rate constant value for the former. [ABSTRACT FROM AUTHOR]

This paper aims to present the mechanism study of methylene blue (MB) discoloration using spent Li-ion battery cathode tape and hydrogen peroxide. The recycled cathode used in this work is composed of 72% of LiCoO2, 18% of carbon, and 10% of Al. The value found for surface area is 8.9 m2/g and the ZCP value occurs in pH = 2.95. Different from what is proposed in the literature, the most likely mechanism of methylene blue discoloration is the oxidation/delitiation of LiCoO2 and the reduction of H2O2 forming OH∙. Thus, in this paper, an important and promising alternative for discoloration of textile industry dyes using spent Li-ion battery cathode is presented. [ABSTRACT FROM AUTHOR]

The development of composite adsorbent coating based acrylic polymer solution (APS) mixed with bentonite (ben) was investigated. The composite adsorbent coating was prepared and coated to a high surface area substrate, cotton cellulosic fiber (CCF). The APS/ben-CCF was used for a single cationic methylene blue (MB) dye adsorption system. Characterization of composition and structure of materials and coating was carried out by X-ray fluorescence (XRF), scanning electron microscopy (SEM), and UV-spectroscopy (UV-VIS). The adsorption properties of the APS/ben-CCF were investigated as a function of solution pH, initial dye concentration and contact time as well as solution temperature of MB dye. The result revealed that the APS/ben-CCF functioned well in solutions of various pH (acidic to alkaline), achieving 100% removal of MB within 2 hours of adsorption for 50 ppm. Kinetic studies showed that APS/ben-CCF is endothermic in nature since the adsorption capacity increased with increasing solution temperature. These results demonstrate that APS/ben-CCF composite adsorbent coating is an advanced adsorbent with advantages such as easy phase separation and capability to remove cationic dyes in a short time period. [ABSTRACT FROM AUTHOR]

A novel, colorimetric, temperature-activated humidity indicator is presented, with a colour change based on the semi-reversible aggregation of thiazine dyes (esp. methylene blue, MB) encapsulated within the polymer, hydroxypropyl cellulose (HPC). The initially purple MB/HPC film is activated by heat treatment at 370 °C for 4 s, at which point the film (with a colour associated with that of a highly aggregated form of MB; λ max = 530 nm) becomes blue (indicating the presence of monomeric and dimeric MB; i.e . with λ max = 665; 605 nm respectively). The blue, heat-treated MB/HPC films respond to an ambient environment with a relative humidity (RH) exceeding 70% at 21 °C within seconds, returning to their initial purple colour. This colour change is irreversible until the film is heat-treated once more. When exposed to a lower RH of up to ca. 47%, the film is stable in its blue form. In contrast, a MB/HPC film treated only at 220 °C for 15 s also turns a blue colour and responds in the same way to a RH value of ca. 70%, but it is unstable at moderate RH 37–50% values, so that it gradually returns to its purple form over a period of approximately 6 h. The possible use of the high heat-treated MB/HPC humidity indicator in the packaging of goods that cannot tolerate high RH, such as dry foods and electronics, is discussed. [ABSTRACT FROM AUTHOR]

Uniformly dispersed ultrasmall tungsten oxide nanoparticles (W 18 O 49 ) of sizes around 5–7 nm were synthesized using tungsten hexachloride as tungsten precursor and octadecylamine (ODA) as surfactant and as well as reducing agent. The as-synthesized nanoparticles (NPs) were characterized thoroughly by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and N 2 adsorption desorption isotherm (BET). From the XRD patterns, formation of monoclinic primitive phase of W 18 O 49 was observed while TEM images showed well dispersed particles of sizes 5–7 nm. The surface area of the W 18 O 49 NPs was found to be 27.17 m 2 g −1 . These ultrasmall W 18 O 49 NPs have been studied as photocatalysts for the first time in the degradation of methylene blue (MB). The photocatalytic activity was evaluated in oxidative degradation of MB with H 2 O 2 under solar irradiation. The particles exhibited pronounced activity in degradation of MB as well as efficient recyclability. The small band gap energy of W 18 O 49 NPs and their large surface area helps in the production of higher electron (e − ) and hole (h + ) pairs which in a way also prevents the e − and h + pairs from recombination within the nanoparticles. This greatly improves and enhances the photocatalytic activity of our synthesized nanoparticles. [ABSTRACT FROM AUTHOR]

A new method was developed for the efficient spectrophotometric determination of methylene blue (MB) dye in solutions. The method is based on a combined dispersive solid phase and cloud point extraction using Cu(OH) nanoflakes (as an adsorbent). Cu(OH) nanoflakes were synthesized by facile and fast methods and characterized using various techniques. The developed method is based on the adsorption of MB on the Cu(OH) nanoflakes and transfer into a surfactant-rich phase using Triton X-114 as a nonionic surfactant. Subsequently, MB dye is desorbed from Cu(OH) nanoflakes using a mixture of nitric acid and methanol solution and determined by UV-Vis spectrophotometry. The effects of pH, amount of Cu(OH) nanoflakes, volume (concentration of Triton X-114), and temperature were investigated by designing experiments using response surface methodology (RSM). A quadratic model was utilized to predict the variables. Analysis of variance (ANOVA) was applied for the analysis of variables and their interactions, and optimal conditions were established. The results demonstrated logical agreement between experimental and predicted values of the response owing to high F value, low P value, and low lack-of-fit. The calibration graph was linear in the range of 2.0-350.0 μg L of MB dye with a correlation coefficient ( R) of 0.9996. The limits of detection and quantification were found to be 0.65 and 2.05 μg L, respectively. The developed method was successfully applied to different water samples, thereby confirming the applicability of the approach. [ABSTRACT FROM AUTHOR]

Alternative treatments, such as, NaOH, ultrasound assisted (UA) and supercritical CO2 (SCO2), were performed to improve the potential of rice husk as adsorbent to remove methylene blue (MB) from aqueous media. All the treatments improved the surface characteristics of rice husk, exposing its organic fraction and/or providing more adsorption sites. The Langmuir and Hill models were able to explain the MB adsorption for all adsorbents in all studied temperatures. The experimental and modeled parameters demonstrated that the MB adsorption was favored by the temperature increase and by the use of NaOH-rice husk. The maximum adsorption capacities for the MB solutions (ranging from 10 to 100 mg L-1), estimated from the Langmuir model at 328 K, were in the following order: NaOH rice-husk (65.0 mg g-1)>UA-rice husk (58.7 mg g-1)>SCO2-rice husk (56.4 mg g-1)> raw rice husk (52.2 mg g-1). The adsorption was a spontaneous, favorable and endothermic process. In general, this work demonstrated that NaOH, UA and SCO2 treatments are alternatives to improve the potential of rice husk as adsorbent. [ABSTRACT FROM AUTHOR]

Phase pure, trigonal, mesoporous Fe/Al/La trimetallic nano-oxide (abbreviated as FAL) was synthesized using energy efficient chemical route with bandgap 1.97 eV and S BET = 50.02 m2/g and an average pore size of 8.95 nm for photodegradation of azo (di and tri) and thiazine class of dyes successfully. The valence band and conduction band potentials were calculated using the Mott-Schottky plot. The highest photodegradation efficiency was 93.85 ± 2% for reactive black 5 (RB5) at pH 7 under solar irradiation. The phase formation of FAL was confirmed by PXRD, TEM, and HRTEM analyses. The other characterizations include FESEM, Raman, EPR, UV, HPLC, LC-MS, etc. The presence of the metal centers and their corresponding oxidation states were confirmed by the SAEDS, elemental mapping, and XPS analyses respectively. FAL was also able to photodegrade direct blue 71 (DB71) and methylene blue (MB) under the same condition at different pH efficiently (pH 2–11). The photodegradation obeyed the pseudo-1st-order kinetics and was reusable up to 5 successive cycles. This study may be an efficient tool to meet UNs' SDG:6. [ABSTRACT FROM AUTHOR]

Background: A simple hydrothermal process was applied to synthesize the doped TiO particles with different concentrations as well as different metal ions (Mn, Ce and La). Methods: The synthesis of Mn-doped-TiO nanoparticles was done by using a hydrothermal method from hydrolysis of titanium tetrachloride in aqueous solution. The photocatalytic activities were checked by studying the degradation of two model organic pollutants. Results: The material was characterized by X-ray diffraction, scanning electron microscopy, and UV-Visible spectroscopy. The X-ray diffraction pattern studied for doped TiO particles suggests the anatase phase with a crystalline nature. Doped TiO particles showed a porous and complex nature with a highly rough surface. The photocatalytic activity of Mn- Ce- and La-doped TiO with different metal-ion concentrations of 0.15-0.60% show that the degradation rate of all of the pollutants increases with an increase in the dopant concentration from 0.15 to 0.45%, and a further increase in the dopant concentration decreased the degradation rate. Conclusions: The results indicate that TiO2 with a concentration of 0.45% for all metal ions (Mn, Ce and La) shows the highest activity. Among studied dopent TiO2 with Mn (0.45%) showed the best degradation activity. [ABSTRACT FROM AUTHOR]

Indoor fungi growth is an increasing home health problem as our homes are more tightly sealed. One thing that limits durability of the antifungal agents is the scarcity of reactive sites on many surfaces to attach these agents. In order to increase graft yield of photosensitizers to the fabrics, poly(acrylic acid-co-styrene sulfonic acid-co-vinyl benzyl rose bengal or phloxine B) were polymerized and then grafted to electrospun fabrics. In an alternative process, azure A or toluidine blue O were grafted to poly(acrylic acid), which was subsequently grafted to nanofiber-based and microfiber-based fabrics. The fabrics grafted with photosensitizers induced antifungal effects on all seven types of fungi in the order of rose bengal > phloxine B > toluidine blue O > azure A, which follows the quantum yield production of singlet oxygen for these photoactive dyes. Their inhibition rates for inactivating fungal spores decreased in the order of P. cinnamomi, T. viride, A. niger, A. fumigatus, C. globosum, P. funiculosum, and M. grisea, which is associated with lipid composition in membrane and the morphology of fungal spores. The antifungal activity was also correlated with the surface area of fabric types which grafted the photosensitizer covalently on the surface as determined by the bound color strength. [ABSTRACT FROM AUTHOR]

Sugarcane bagasse, an agricultural waste biomass was used to prepare biochar by pyrolyzing the biomass under oxygen-limited conditions. The prepared biochar was used for the adsorptive removal of a cationic dye methylene blue (MB) under a magnetic field. It was found that the existence of the external magnetic field had significantly enhanced the uptake of MB onto the bagasse biochar. The increased biochar dosage actually declined the uptake of MB while the effect of the magnetic field was still significant. The adsorption kinetics was investigated under different solution pH conditions. The experimental data were simulated using non-linear pseudo-first-order, pseudo-second-order and Elovich kinetic models. The Elovich kinetic model was found to be more suitable to describe the adsorption kinetics. This indicates that the adsorption of MB onto BC400 is a chemisorption process in which the rate-determining step is diffusion in nature. The uptake of MB is mainly attributed to the electron-donor-acceptor interaction and electrostatic attraction. [ABSTRACT FROM AUTHOR]

This study presents the electrochemical degradation of methylene blue (MB) wastewater in a synthetic solution using three-dimensional particle electrodes. The novel particle electrodes were fabricated in this work using the lithium modified rectorite (Li-REC). The adsorption property of the fabricated particle electrodes was studied in a series of experiments. The optimum electrochemical operating conditions of plate distance, cell voltage, and concentration of electrolyte were 2 cm, 9 V, and 0.06 mol L−1, respectively. It was also found that microwave irradiation can effectively improve the adsorption property and electrical property of the fabricated electrodes. In addition, the scanning electron microscope (SEM) of the fabricated electrodes was investigated. The experimental results revealed the order of adsorption property and electrical property of the fabricated electrodes. So, fabricated electrodes are not only of low cost and mass produced, but also efficient to achieve decolorization of MB solution. [ABSTRACT FROM AUTHOR]