Triphenylmethane Dyes Research Articles

Photocatalytic Degradation of Organic Dyes from Clinical Laboratory Wastewater

Clinical laboratory wastewaters are of important environmental concern due to the highly complex chemical reagents and dyes used to identify various pathologies, which are difficult to degrade by conventional treatment methods. The present research aimed to assess the effects of ilmenite use in the discoloration process of clinical laboratory wastewater. The wastewater originates from a Gram staining process used to identify pathogenic microorganisms present in biological samples. The active ingredient is crystal violet, a triphenylmethane dye derivative, highly toxic and non-biodegradable that causes a shiny purple color in the wastewater. The ilmenite was characterized by X-ray Fluorescence, X-ray Diffraction, Scanning Electron Microscopy, energy-dispersive spectroscopy and Nitrogen adsorption isotherm, while the discoloration process of the wastewater was measured by UV–Vis spectrophotometry and pH change trough the reaction time, evaluating different ilmenite loads, particle size and stability under light sources with different energies. Chemical oxygen demand analysis confirmed that acid formation and discoloration were associated with organic substance mineralization. Type C ultraviolet light and 0.7 g/L load were identified as the best operating conditions for the discoloration process. It was possible to establish that ilmenite is stable after four uses in the discoloration process, obtaining, in all cases, discoloration percentages higher than 90% after 3 h of irradiation.

Simple adsorptive removal of crystal violet, a triarylmethane dye, from synthetic wastewater using Fe (III)-treated pine needle biochar.

Untreated and Fe (III)-treated pine needle biochar (PNB) were evaluated at different pH for the removal of toxic crystal violet (CV) dye from synthetic wastewaters. Adsorption kinetics followed the pseudo-first-order kinetics involving intra-particle diffusion process. The adsorption rate constant increased with Fe treatment of PNB especially at pH 7.0. Adsorption data of CV conformed well to Freundlich adsorption isotherms and both adsorption capacity (ln K) and order of adsorption (1/n) of CV were nearly doubled with Fe (III) treatment of PNB at pH 7.0. Desorption of adsorbed CV from both untreated and Fe (III)-treated PNB could be accounted satisfactorily by third-degree polynomial equations. An increase in ionic strength and temperature enhanced dye adsorption onto untreated and Fe (III)-treated PNB. Adsorption of CV was an endothermic and spontaneous reaction with an increase in entropy of the system. FTIR spectra revealed that C = O of carboxylic acid aryls and C = O and C-O-C in lignin residues of PNB reacted with Fe (III) besides the formation of some iron oxyhydroxide minerals. The changes in FTIR confirmed the possible bonding of positively charged moiety of CV with the untreated and Fe-treated PNB. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) revealed the porous surfaces of PNB with clear accumulation of Fe (III) after treatment and deposition of CV dye on surfaces and pores of PNB. Iron (III)-treated PNB at pH 7.0 can serve as an ecofriendly and cost-effective adsorbent for the efficient removal of CV dye from wastewaters.

Degradation of the Chromophore Functions of Dyes in Irradiated Solutions

Radiolysis damages the system of conjugated bonds and thus leads to the degradation of the chromophore functions of dyes in aqueous solutions. Ten representatives of quinophthalone, indigo, triphenylmethane, and azo dyes exhibited the same type of correlations between the absorbed dose and the degree of discoloration. It was shown using the method of competing scavengers that the color of aerated solutions decreased mainly due to the addition of OH radicals to the dyes. The radiation-chemical yields of discoloration ranged from 0.03 to 0.11 μmol/J and increased depending on the length of bond conjugation in the dye molecules. For practical electron-beam discoloration of dye solutions with a concentration of 20 mg/dm3, anabsorbed dose of 1–1.5 kGy was sufficient.

Decolorization of Dyes in the Bioelectrochemical System Depending on the Immobilization of <i>Shewanella oneidensis</i> MR-1 Cells on the Anode Surface and Electrical Stimulation of the External Circuit

The effect of the polarity of the electrical stimulation of the external circuit of the bioelectrochemical systems, as well as the immobilization of Shewanella oneidensis MR-1 cells containing the DyP peroxidase gene on the rate of discoloration of dyes of different types was found. For the crystal violet triphenylmethane dye, the maximum decolorization rate by suspended S. oneidensis MR-1 cells 2.05 ± 0.07 μM/h was noted in the case of connecting a 1.2 V direct polarity DC voltage source. One of the minimum rates was observed in the case of reverse polarity of the connection. In the case of cells immobilized on the anode, the rate was higher, reaching 2.91 ± 0.09 μM/h and did not decrease with increasing substrate concentration. The lowest values were also noted for the reverse connection of the voltage source. In case of the azo dye congo red, the maximum rate was found for a source with direct connection and an open circuit (0.26 ± 0.01 and 0.29 ± ± 0.02 μM/h, respectively), the minimum value is 0.11 ± 0.02 μM/h for reverse connection. For the crystal violet decolorization products, a significant decrease in the intensity of the main absorption peak at 590 nm band was found, with no notable hypsochromic shift. The qualitative changes in the decolorization products composition are indicated by the appearance, in case of a direct polarity of the ionistor connection, of a new absorption maximum in the region of 360 nm. The results may be of interest for the development of new methods of bioelectrochemical cleaning.

Biosynthesis of multifunctional Fe3O4/cocoa pod carbon composite and its versatile role as sonoadsorbent in triphenylmethane textile dye remediation and potential cathode material for energy storage applications

Iron oxide embedded cocoa pod carbon (C@Fe3O4) composite was tailored effectively by the green synthetic route. The multi-functionality of the synthesised nanocomposite was evaluated through its potential suitability for environmental amelioration and energy storage applications. The synthesised composite was characterised by employing various analytical techniques, and the electrochemical aspects were investigated using galvanostatic charge–discharge and cyclic-voltammetry techniques. The magnetic carbon composite exhibits excellent amelioration of triphenylmethane dye from the aquatic matrix. The maximum adsorption capacity of the crystal violet achieved was 804.9 mg/g, following the Langmuir isotherm model and fitting pseudo second-order kinetics. Furthermore, the composite was evaluated for energy storage applications and demonstrated excellent specific capacity of 30.04 mAh/g with outstanding retention of 87.71 %, rendering it a possible cathode choice for potential sustainable energy storage systems.

Ultrasound assisted synthesis of Fe‐TiO2 and Ce‐TiO2 catalysts and subsequent application for photocatalytic, sonocatalytic, and sonophotocatalytic decolorization of basic Victoria blue dye

AbstractSynthesis of Fe‐TiO2 and Ce‐TiO2 catalysts using conventional, and ultrasound assisted (US) homogeneous coprecipitation method has been investigated. Effects of ultrasonic irradiation time and ultrasonic power on catalyst synthesis were studied and it was elucidated that best conditions were 140 W and 60 min, respectively. Characterization using FE‐SEM revealed spherical particles with the size range from 36.4 to 49.4 nm whereas XRD analysis affirmed a mixture of anatase, rutile, and brookite TiO2 phase with crystallite size ranging from 4.18 to 12.99 nm. BET analysis revealed highest specific surface area (211.59 m2/g) for the sonochemically synthesized Ce‐TiO2. The process intensification benefits demonstrated in catalyst synthesis were better crystallinity, lower particle size, and higher surface area. The application of catalyst efficacy was tested for photocatalytic, sonocatalytic, and sonophotocatalytic oxidation where maximum decolorization as 71.97% was obtained for sonochemically synthesized Ce‐TiO2 applied in the sonophotocatalytic approach. Studies related to regeneration, stability, and leaching of Ce and Ti ion from the sonochemically synthesized Ce‐TiO2 catalyst were also performed. It was observed that the catalyst can be regenerated easily and there were no structural changes in the catalyst after regeneration with negligible leaching of the ions from the catalyst into the solution. Overall, an improved process for catalyst synthesis with intensified decolorization application was demonstrated based on the use of ultrasound.

A Histogram-Based Technique for Simultaneous Colorimetric Determination of Malachite Green and Brilliant Green Using Triton X-100 Micelle.

Malachite green (MG) and brilliant green (BG) are two synthetic triphenylmethane dyes with applications in the textile and aquaculture industries. They are considered to be environmental contaminants due to their carcinogenic and mutagenic properties. Both dyes have the same bluish-green color in aqueous solutions. The aim of this study is to develop a colorimetric analysis as a very simple and cost-effective method to determine the residues of MG and BG simultaneously in aqueous industrial samples. This method is based on the alterations in red, blue, green (RGB) color histograms of the dyes in the presence and absence of Triton X-100 micelle. The images of the samples were taken by a digital camera and converted to the RGB color system using MATLAB software. Partial least-squares regression as a powerful chemometrics tool was used for multivariate calibrations and quantitative measurements. The performance of the proposed method was compared with a simple spectrophotometric method as a reference. Relative errors of prediction for colorimetric and spectrophotometric analysis, respectively, in micellar media were 6.56 and 4.61% for MG and 6.38 and 5.24% for BG. The shortest linear ranges for colorimetric and spectrophotometric analysis, respectively, in micellar media were 0.1-10 and 0.5-5 mg/L for MG and 0.1-15 and 0.5-6 mg/L for BG. The recovery percentages obtained from the analysis of the dyes in real samples of fish-pond water and textile wastewater ranged between 91 and 107%. The good correlation between the results of the colorimetric analysis and the spectrophotometric analysis indicates the reliability of the proposed colorimetric method. Also, the results of the relative recovery study showed insignificant matrix effect. This study demonstrates the ability of the colorimetric analysis coupled with chemometrics tools for simultaneous determination of the analytes even with nearly identical colors.

A systematic study of SERS spectra of cationic Raman dyes adsorbed on citrate-stabilized silver nanoparticles

The adsorption (kinetics and signal stability) of cationic triarylmethane dyes and an acridine derivative with various counter-ions on citrate-stabilized hydroxylamine-reduced silver sols was studied using SERS spectroscopy. The influence of the method of nanoparticle synthesis, as well as the composition and ionic strength of the medium on the stability of nanoparticle–dye complexes was investigated.

Efficient degradation and decolorization of triphenylmethane dyes by Serratia sp. WKD under extreme environmental conditions and the mechanism

Microbial degradation of dyes is fundamental and essential for understanding their environmental fate. In this study, a new bacterial strain with efficient degrading capability of triphenylmethane (TPM) dyes named WKD was isolated and identified as the genus Serratia sp. by 16S rDNA analysis. The decolorization of TPM dyes by the strain especially under extreme environmental conditions were studied. The results showed that the strain could completely decolorize Malachite Green (MG) and Crystal Violet (CV) at pH values ranging from 3.0 to 10.0 and at temperatures ranging from 20 °C to 45 °C in a 12 h of incubation. The strain still showed an excellent decolorizing capability even at low (5 °C) and high (60 °C) temperatures. Moreover, the enzymatic analysis indicated that MnP, NADH-DCIP reductase, MG reductase, and CV reductase might be involved in TPM dyes biodegradation. Besides, the biodegradation pathways were proposed based on UV–visible, FTIR, and LC-Q-TOF-MS analyses. Results indicated that degradation of MG by the strain was mainly regulated by N-demethylation and hydroxylation pathways, while degradation of CV was only by the N-demethylation pathway. Therefore, Serratia sp. strain WKD is expected to have a broad application prospect for the bioremediation of TPM dyes, especially in extreme environments.

Enhanced Removal of Organic Dyes Using Co-Catalytic Ag-Modified ZnO and TiO2 Sol-Gel Photocatalysts

Zinc oxide and titanium dioxide semiconductor photocatalysts have been widely utilized in the last few decades for water treatment because of their high photocatalytic efficiency. Recently, a lot of researchers have focused on the improvement of the photocatalytic properties of catalysts through modifying and co-modifying them with different metals and nonmetals. These co-catalytic ions improve the photocatalytic activity of ZnO and TiO2 by reducing its energy band gap. This might be useful in wastewater treatment for the photocatalytic degradation of organic contaminants. In this study, we prepared semiconductor films that were surface-modified with Ag co-catalyst layers via the photo-fixation of Ag (I) ions with varied concentrations (10−2–10−4 M) in the water phase under UV illumination for the first time. The photocatalytic behavior was evaluated by the degradation of malachite green and methylene blue under UV and visible light irradiation. The ZnO/Ag and TiO2/Ag samples showed a faster degradation of malachite green compared to methylene blue due to the formation of stable intermediates by the reaction of OH radicals with the triarylmethane dye (C=C bond) during the photocatalysis. The co-catalytic-silver-modified films had a higher photocatalytic efficiency in comparison with the pure nanostructures. The dye photodegradation rate constants increased in the following order: pure films < films modified with Ag, 10−4 M < films modified with Ag10−3 M < films modified with Ag10−2 M. The Ag modification and the heterojunction of the composites contributed to trapping and transfer of the electrons. Therefore, the photogenerated charges had a longer lifetime, resulting in a strengthened photocatalytic ability of the ZnO/Ag and TiO2/Ag films.

Plasma modified Co3O4 nanoparticles for catalytic degradation process through enhanced peroxidase-like activity

This study highlights a simple and efficient nanochemistry-based approach for the effective degradation of triphenylmethane and toxic dye, malachite green (MG) using Argon cold plasma-modified cobalt oxide nanoparticles (Ar-Co3O4-NPs). Synthesized particles were characterized using scanning electron microscope, X-ray diffraction, and Fourier-transform infrared spectroscopy. The peroxidase-mimic activity of Co3O4-NPs was evaluated, and the results confirmed that the catalytic activity of Co3O4-NPs was enhanced after plasma modification. The decomposition of MG was tested using the improved catalytic activity of Ar-Co3O4-NPs in model aqueous solution. The results indicated the ability of 0.16 g/mL Ar-Co3O4-NPs to completely degrade 40 µM MG within 70 min with a decolorization efficiency of 96.78%. Experimental conditions were optimized for maximum MG removal. Gas chromatography-mass spectrometry was used to determine the byproducts of MG degradation, and the findings indicated the production of less toxic products. The toxicity of the resultant metabolites of MG degradation was evaluated against E. coli and B. subtilis and the results confirmed less toxic product formation. Artificial neural networks (ANNs) were used to model the catalytic degradation data, and the strong correlation between experimental observations and ANN model predictions suggested that the designed model could accurately predict MG dye removal efficiency under different operating conditions.

Electrochemical degradation and mineralisation of organic dyes in aqueous nitrate solutions

Electrochemical treatment of organic matter for environmental remediation necessitates the development of cheap and robust electrodes that are chemically and structurally stable. To address this challenging requirement, we demonstrate a new electrochemical approach using a simple copper electrode under cathodic conditions to electrochemically generate reactive nitrosonium ions for the degradation of different classes of synthetic organic dyes. This could be achieved in an aqueous HNO3/KNO3 electrolyte at a relatively low cathodic potential of −0.5 V RHE at room temperature. UV–visible absorption spectroscopy, Raman spectroscopy, liquid chromatography – mass spectrometry and total organic carbon measurements revealed the rapid decolorisation and mineralisation of several dye types such as triarylmethane dyes (crystal violet, cresol red), an azo dye (methyl orange) as well as a sulfur containing thiazine dye (toluidine blue). The total organic carbon content of a 50 mg L−1 methyl orange solution was found to decrease by 83% after 1 h of electrolysis. Promisingly, locally sourced river and creek water samples spiked with 50 mg L−1 methyl orange were also successfully treated for up to 6 cycles at a simple Cu electrode, demonstrating potential for the remediation of polluted waterways.

Degradation by hydrolysis of three triphenylmethane dyes: DFT and TD-DFT study

Degradation by hydrolysis of three triphenylmethane dyes: DFT and TD-DFT study

Real-time in situ monitoring using visible spectrophotometry as a tool for probing electrochemical advanced oxidation processes for dye decolorisation.

An apparatus for real-time in situ monitoring of electrochemical processes using UV-visible spectrophotometry has been used to optimise the electrochemically-activated persulfate decolorisation of Acid Orange 7. The impacts of varying electrode composition, current density, persulfate loading, and stirring speed on the rate of decolorisation have been probed. Decolorisation through this activated persulfate approach was compared to that using anodic oxidation for nine dyes; three from each of the azo, triarylmethane, and xanthene families. The core structure and presence of functional groups have a significant impact on the rate of decolorisation. Azo and xanthene dyes decolorise faster than triarylmethane dyes, while electron-withdrawing groups and halogens are especially detrimental to the rate of decolorisation. Electrochemically-activated persulfate resulted in faster decolorization than anodic oxidation for almost every dye, an effect that was enhanced with the electron-deficient substrates. This type of systematic structural comparison study is essential for designing electrochemical degradation procedures for the remediation of real wastewater.

Interaction of Victoria Blue Dye in Anionic and Cationic Micellar Media: Spectroscopic Study

This manuscript has reported the micellar interaction of cationic triphenylmethane-based dye andquot;Victoria Blue-B (VBB)andquot;. The study was conducted using ionic surfactants viz. Cetyltrimethylammonium Bromide (CTAB)] Sodium Dodecyl Sulphate (SDS), and Sodium Docusate (SD). The behavior of dye in micellar media at concentration ranges of the surfactants mentioned above was monitored by UV-vis absorption spectroscopic study. The solubilization parameters to reveal the interaction of cationic dye in micellar media were assessed. The mathematical calculations of partition constant (Kc), partition coefficient (Kx), binding coefficient (Kb), Gibb’s free energy for partition (ΔGp) and binding (ΔGb) were derived from UV–Vis absorption data. The presence of anionic surfactants caused more bathochromic shifts in the maximum absorption of the dye, which was indicative of strong interactions as compared to the cationic surfactant.

Fabrication of novel porous ZIF-67/PES composite microspheres and the efficient adsorption of triphenylmethane dyes from water

The porous ZIF-67/PES composite microspheres have good MG, FA and CV adsorption performance, which is mainly attributed to π–π superposition between MG, FA and CV and the porous ZIF-67/PES composite microspheres.

An efficient P3TA/Fe doped TiO2 catalyst for photo-degradation of Brilliant green dye and inactivation of pathogens under visible light

Brilliant green (BG) belongs to triarylmethane dyes which cause nausea, vomiting, abdominal pain, burning skin or eyes, irritation and diarrhoea. Advanced oxidation process (AOPs) is the ample to removal BG dye from its contamination using semiconductor. TiO2 has proved the benign photo-catalyst for UV light absorption. Doping or co-doping with metal increase the photocatalytic performance, so in this study, poly3-thenoic acid assisted P3TA/Fe doped TiO2 nano-hybrid was prepared via sol–gel approach to assist photocatalytic degradation of BG dye. Analytical instruments were employed in this study to characterize the prepared nano hybrid. BG dye is a model pollutant in this study to examine the photocatalytic performance of proposed P3TA/Fe doped TiO2 nano-hybrid under visible light irradiations and it degrade BG dye completely in 60 min under visible light illuminations. As a result, the results reveal that 0.20 g of P3TA/Fe-TiO2 at pH 10 is a good photo-catalyst for degrading 10 mg/L BG dye solution efficiently. In addition, antibacterial assay also determined over the pathogens of E.coli and S.aureus. This study helps in prepare more efficient photo-catalysts for the removal of dye pollutants from their contaminated water in a large-scale industry.

Efficient decolorization and detoxification of triarylmethane and azo dyes by porous-cross-linked enzyme aggregates of Pleurotus ostreatus laccase

In this preset study, porous-cross-linked enzyme aggregates (CLEAs) of Pleurotus ostreatus laccase were utilized for the spontaneous decolorization and detoxification of triarylmethane and azo dyes, reactive blue 2 (RB) and malachite green (MG). The specific surface area and pore radius of the porous-CLEAs are 136.3 m2/g and 19.47 Ao, and the higher specific surface indicated greater biocatalytic efficiency, as increased mass transfer and dye interaction with the CLEAs laccase. CLEAs laccase decolorized 500 ppm of MG and RB with 98.12–58.33% efficiency after 120 min, at pH 5.0 and 50°C, without a mediator. Furthermore, the biotransformation of the MG and RB with immobilized laccase was confirmed with the help of UV–visible spectroscopy, high-performance liquid chromatography, and Fourier transform infrared spectroscopy. The reusability potential of CLEAs was assessed in batch mode for 10 cycles of dye decolorization. The decolorization activities for the immobilized laccase were 89% and 12% at the 6th cycle for MG and RB, respectively. This immobilized enzyme could effectively remove dyes from aqueous solution, and demonstrated significant detoxification in experimental plants (Triticum aestivum and Phaseolus mungo) and plant growth-promoting rhizobacteria (Azospirillum brasilense, Bacillus megaterium, Rhizobium leguminosarum, Bacillus subtilis, and Pseudomonas fluorescens). In conclusion, porous CLEAs laccase could be useful as a potential bioremediation tool for the detoxification and decolorization of dyeing wastewater in future.

Influence of the Alcohols on the ZnO Synthesis and Its Properties: The Photocatalytic and Antimicrobial Activities.

Zinc oxide (ZnO) nanomaterials are used in various health-related applications, from antimicrobial textiles to wound dressing composites and from sunscreens to antimicrobial packaging. Purity, surface defects, size, and morphology of the nanoparticles are the main factors that influence the antimicrobial properties. In this study, we are comparing the properties of the ZnO nanoparticles obtained by solvolysis using a series of alcohols: primary from methanol to 1-hexanol, secondary (2-propanol and 2-butanol), and tertiary (tert-butanol). While the synthesis of ZnO nanoparticles is successfully accomplished in all primary alcohols, the use of secondary or tertiary alcohols does not lead to ZnO as final product, underlining the importance of the used solvent. The shape of the obtained nanoparticles depends on the alcohol used, from quasi-spherical to rods, and consequently, different properties are reported, including photocatalytic and antimicrobial activities. In the photocatalytic study, the ZnO obtained in 1-butanol exhibited the best performance against methylene blue (MB) dye solution, attaining a degradation efficiency of 98.24%. The comparative study among a series of usual model dyes revealed that triarylmethane dyes are less susceptible to photo-degradation. The obtained ZnO nanoparticles present a strong antimicrobial activity on a broad range of microorganisms (bacterial and fungal strains), the size and shape being the important factors. This permits further tailoring for use in medical applications.

Ag-Fe3O4 nanozyme with peroxidase-like activity for colorimetric detection of sulfide ions and dye degradation

Nanozymes based on metal are attractive substitutes to natural enzymes because of stability and low cost. At present, it is a great challenge to obtain highly active and specific metallic nanozyme for chemo-sensing and catalytic degradation toxic dye. Herein, Ag-Fe3O4 nanozymes were constructed via covalently bond to Fe3O4 using silver nanoparticles as a metal center. The peroxidase-like activity of single Ag is very weak even negligible. The Km value of Ag-Fe3O4 for TMB was 4.2-fold lower than that of single Fe3O4 nanozyme. Then, a TMB/H2O2/Ag-Fe3O4 colorimetric platform was developed for sulfur ions in the linear range of 10–100 μM, with a detection limit of 0.4 μM. In addition, Ag-Fe3O4 nanozyme quickly and specifically catalyzed the degradation of triarylmethane dyes, and the degradation rate was more than 99%, along with good reusability more than ten-cycle run.