Safranine O Research Articles

Application of ANN and RSM for Rhodamine B and Safranine-O Decolorization on Zinc-Carbon Battery Waste Derived Ag/CoFe-LDH/rGO Catalyst.

The present work is first aimed at recovering graphite from carbon rods of waste zinc-carbon (Zn-C) batteries for applications such as wastewater treatment, in order to contribute to the development of a sustainable environment. Then, a composite material, cobalt-iron layered double hydroxide combination with reduced graphene oxide, and with subsequent Ag nanoparticles deposition via NaBH4 reduction method (Ag/CoFe-LDH/rGO) was prepared for the catalytic activity of Rhodamine B (RhB) and Safranine-O (SO) as model contaminants from aquatic media. The catalytic activity of RhB and SO by Ag/CoFe-LDH/rGO in the presence of NaBH4 was studied to model and optimize the process parameters (NaBH4 amount, reaction time, initial dye concentration (Co), and catalyst dosage) via central composite design (CCD)-response surface methodology (RSM). Also, an artificial neural network (ANN) model was developed to estimate the catalytic activity of each dye using an RSM data set. The catalytic activities of 99.54% and 99.96% were obtained for RhB and SO dyes, respectively, under the optimal conditions: NaBH4 amount 12.32 mM, reaction time 3.19 min, Co 33.46 mg/L, and catalyst dosage 1.24 mg/mL for RhB dye; NaBH4 amount 16.76 mM, reaction time 3.06 min, Co 15.10 mg/L, and catalyst dosage 1.46 mg/mL for SO dye. The optimum conditions of process parameters by ANN with gray wolf optimizer (GWO) were in good agreement with the points determined the RSM-CCD. These results demonstrate that RSM and ANN approaches can be applied practically and efficiently to maximize the catalytic activity of RhB and SO by Ag/CoFe-LDH/rGO in the existence of NaBH4. On the other hand, from the kinetic and thermodynamic studies, the positive activation enthalpy, ΔH# and the negative activation entropy, ΔS# values for each dye demonstrated that the catalytic performance was endothermic and less random at the solid/liquid interface.

Bio-nanoparticles loaded with synovial-derived exosomes ameliorate osteoarthritis progression by modifying the oxidative microenvironment

Background and aimsOsteoarthritis (OA) is a prevalent degenerative joint disorder, marked by the progressive degeneration of joint cartilage, synovial inflammation, and subchondral bone hyperplasia. The synovial tissue plays a pivotal role in cartilage regulation. Exosomes (EXOs), small membrane-bound vesicles released by cells into the extracellular space, are crucial in mediating intercellular communication and facilitating the exchange of information between tissues. Our study aimed to devise a hydrogel microsphere infused with SOD3-enriched exosomes (S-EXOs) to protect cartilage and introduce a novel, effective approach for OA treatment.Materials and methodsWe analyzed single-cell sequencing data from 4247 cells obtained from the GEO database. Techniques such as PCR, Western Blot, immunofluorescence (IF), and assays to measure oxidative stress levels were employed to validate the cartilage-protective properties of the identified key protein, SOD3. In vivo, OA mice received intra-articular injections of S-EXOs bearing hydrogel microspheres, and the effectiveness was assessed using safranine O (S.O) staining and IF.ResultsSingle-cell sequencing data analysis suggested that the synovium influences cartilage via the exocrine release of SOD3. Our findings revealed that purified S-EXOs enhanced antioxidant capacity of chondrocytes, and maintained extracellular matrix metabolism stability. The S-EXO group showed a significant reduction in mitoROS and ROS levels by 164.2% (P < 0.0001) and 142.7% (P < 0.0001), respectively, compared to the IL-1β group. Furthermore, the S-EXO group exhibited increased COL II and ACAN levels, with increments of 2.1-fold (P < 0.0001) and 3.1-fold (P < 0.0001), respectively, over the IL-1β group. Additionally, the S-EXO group showed a decrease in MMP13 and ADAMTS5 protein expression by 42.3% (P < 0.0001) and 44.4% (P < 0.0001), respectively. It was found that S-EXO-containing hydrogel microspheres could effectively deliver SOD3 to cartilage and significantly mitigate OA progression. The OARSI score in the S-EXO microsphere group markedly decreased (P < 0.0001) compared to the OA group.ConclusionThe study demonstrated that the S-EXOs secreted by synovial fibroblasts exert a protective effect on chondrocytes, and microspheres laden with S-EXOs offer a promising therapeutic alternative for OA treatment.

Natural self-assembled supramolecules as green inhibitors against methane hydrate formation

Environmentally friendly hydrate inhibitors are the most promising method to solve the environmental pollution of inhibitors, among which Safranine O (SO) with antifreeze protein properties shows excellent application prospects. SO will self-assemble into macromolecules under hydrogen bonding and electrostatic action in an aqueous solution. The assembled macromolecules' hydrophobic and hydrophilic functional groups are regularly arranged with the properties of an antifreeze protein. In the crystal growth inhibition (CGI) test, the supercooling degree of the complete inhibition region (CIR) of 1.0 wt% SO solution for SI hydrate was significantly higher than that of 1.0 wt% PVP solution. Further, the acidic environment did not affect the inhibitory effect of SO on hydrate. The complete inhibition range of 1.0 wt% SO solution on SI hydrate at pH 1.4 and 7.1 was 7.41 °C and 8.35 °C, respectively. These results suggest that SO-based KHIs may provide new ideas for developing highly efficient acid-resistant hydrate inhibitors.

Green synthesis of gold nanoparticles by phycoerythrin extracted from Solieria tenuis as an efficient catalyst for 4-nitrophenol reduction and degradation of dyes in wastewater

Algal blooms and untreated wastewater will destroy the environment and ecosystem on which human beings depend. In this study, Solieria tenuis, a potential bloom in some regions of the sea in China, was used to mediate the composite of phycoerythrin (PE) and gold nanoparticles namely Au@PE NPs via a quick, easy, and effective manner. The physicochemical properties of Au@PE NPs were determined through UV–vis spectroscopy (UV–Vis), fluorescence spectroscopy (FP), fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The composite materials with a fine morphology and size (average size of 16 nm) exhibited superior catalytic abilities for the conversion of 4-nitrophenol(4-NP) to 4-aminophenol (4-AP, k298K = 0.36 × 10−2 s) and the degradation of cationic dyes methylene blue (MB) and safranine O (SO) in wastewater. Additionally, the mechanisms of 4-NP's catalytic reduction and decolorization of dyes by Au@PE NPs were proposed. The results indicated that PE could not only act as capping and reducing agents but also enhance solubility and photocatalytic activity of the synthesized gold nanoparticles. The current study provides clear evidence of a potential economic solution for utilizing organisms that are harmful to the environment to develop novel bioconjugated composites with multiple functions for efficient pollutant removal and environmental remediation.

Synthesis, characterization, catalytic reduction of Eosin B dye and C, N cross coupling reactions of sodiumalginate/V2O5 nanocomposite

BackgroundA low cost with high efficiency sodiumalginate (SA)/V2O5 nanocomposite catalyst was synthesized by complexation followed by reduction method. The V2O5 catalyst and SA was chemically linked with each other and hence restriction in diffusion of the catalyst into the reaction medium during the course of the reaction. The catalytic activity of SA/V2O5 bio-nano catalyst system was tested towards the C, N cross coupling reaction and reduction of EB dye. MethodsThe bio-polymer nanocomposite formation was confirmed by FT-IR spectroscopy, 1H-NMR spectroscopy, DSC (Tg) and TGA (Td) and HR-TEM (size) like analytical tools. The cross coupling reaction between rosebengal (RB) and nitrogen containing heterocyclic compounds like indole, benzimidazole, 2-methylimidazole were carried out. Same type of reaction was carried out with congored (CR), acidfuchsin (AF) and safranine O (SO) dyes. Further, the catalytic activity of SA/V2O5 nanocomposite catalyst was tested towards the reduction of Eosin blue (EB) dye. Significant findingsThe FTIR spectrum showed a peak at 615 cm−1 due to the V-O stretching. The 1H-NMR spectrum confirmed that the OH group of SA involved in the complex formation with V atom of V2O5. The Tg and Td of the SA/V2O5 bio-polymer nanocomposite system was higher than that of the neat polymer. The apparent rate constant (kapp) value was found to be higher in the presence of SA/V2O5 catalyst system. The C,N cross coupling reaction was successfully carried out with significant % yield in the presence of low cost and eco-friendly SA/V2O5 nano catalyst. The catalyst was stable up to several cycles of operations.

Adsorptive studies on the removal of dyes from single and binary systems using Saccharum munja plant-based novel functionalized CNT composites

Herein, Saccharum munja (SM) plant biomass and its novel composites with 0.5%, 1% and 2% functionalized carbon nanotube (CNT) were innovatively proposed as a versatile biosorbent for the removal of safranine O (SO) and methylene blue (MB) dyes from the single and binary systems. The morphology, structure and physicochemical properties of the as-fabricated adsorbents were characterized using various techniques such as X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), Field Emission Scanning Electron Microscope (FESEM) and Differential Scanning Calorimetry (DSC). Batch adsorption studies revealed maximum removal of dyes at neutral pH and equilibrium was reached within 10 min of contact time for both the dyes. The adsorption process was modelled by the pseudo-second-order kinetics and Langmuir isotherm, where the maximum adsorption capacity of the 1%CNT+SM composite was enhanced by 336.29% and 35.49% as compared to raw SM, in the case of SO and MB dye respectively. Interestingly, the raw SM and its composites showed a higher affinity in the binary system towards the removal of SO (82.56-95.67%) as compared to MB (80.67-94.24%) dye. Regeneration studies depicted excellent reusability even after the tenth sequential adsorption–desorption cycle, which makes these adsorbents a promising material for wastewater remediation. • Raw Saccharum munja and its composites with functionalized CNT were fabricated. • Safranine O and Methylene Blue dyes were removed effectively using the adsorbents. • The composite of SM with 1% functionalized CNT gave the best results. • Regeneration of all adsorbents was studied up to 10 cycles.

Ethylenediamine grafted carbon nanotube aerogels modified screen-printed electrode for simultaneous electrochemical immunoassay of multiple tumor markers

• Hybrid carbon aerogels were synthesized and introduced for immunosensor application. • The sandwich configuration immunosensor was based on the screen-printed technology. • Redox mediators (dyes) have been used as labels. • The improved immunosensor was employed for individual and simultaneous electrochemical detection of AFP and CEA. • The developed EC sensor provided a sufficient linear range of 0.005–1.0 ng/mL for AFP and CEA. A sensitive sandwich-model immunoassay designed for simultaneous electrochemical measurement of alpha-fetoprotein and carcinoembryonic antigen handling multiple-label strategy. The sandwich-model immunosensor was constructed by assembling ethylenediamine-MWCNT aerogels (EDA-CAGs), AuNPs and capture antibodies (Cp-Ab 1 ) on the screen-printed carbon electrode (SPCE). The prepared EDA-CAG textures were analyzed using Fourier transform infrared (FT-IR), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX). In this protocol, AuNPs decorated EDA-CAG-carried Thionine (Thi) and AuNPs decorated EDA-CAG-carried Safranine O (SfO) (denoted as AuNP-Thi-EDA-CAG and AuNP-SfO-EDA-CAG, respectively) were properly exploited as distinguishable signal labels, which were used to attach detection antibodies (Ab 2 ) (anti-AFP 2 and anti-CEA 2 ), respectively. When two tumor antigens were present, a square wave voltammetry (SWV) scan displayed two well-separated signals, each signal indicated one target antigen. Observed results introduced that the square wave voltammetric peak current exhibited a good linear relationship to logarithm concentration in the ranges from 0.005 to 1.0 ng/mL for both analytes. The LoDs were 0.0015 and 0.0010 ng/mL (at signal/noise S/N = 3) for AFP and CEA, respectively. The designed sandwich-type immunosensor was applied to real serum sample analysis.

Adsorption-Inhibition of Clathrate Hydrates by Self-Assembled Nanostructures.

The mechanism by which safranine O (SFO), an ice growth inhibitor, halts the growth of single crystal tetrahydrofuran (THF) clathrate hydrates was explored using microfluidics coupled with cold stages and fluorescence microscopy. THF hydrates grown in SFO solutions exhibited morphology changes and were shaped as truncated octahedrons or hexagons. Fluorescence microscopy and microfluidics demonstrated that SFO binds to the surface of THF hydrates on specific crystal planes. Cryo-TEM experiments of aqueous solutions containing millimolar concentrations of SFO exhibited the formation of bilayered lamellae with an average thickness of 4.2±0.2 nm covering several μm2 . Altogether, these results indicate that SFO forms supramolecular lamellae in solution, which might bind to the surface of the hydrate and inhibit further growth. As an ice and hydrate inhibitor, SFO may bind to the surface of these crystals via ordered water molecules near its amine and methyl groups, similar to some antifreeze proteins.

Nano-hybrid bimetallic Au-Pd catalysts for ambient condition-catalytic wet air oxidation (AC-CWAO) of organic dyes

In this work, a hybrid of Na2Mo4O13 and MoO3 (NM) was synthesized by a hydrothermal method, and Au-Pd nanoparticles were further deposited on NM by a facile one-pot deposition reduction method to obtain highly active and stable nano-hybrid bimetallic catalysts. The nano-hybrid bimetallic catalysts were systematically characterized and investigated for ambient condition-catalytic wet air oxidation (AC-CWAO) of organic dyes (Brilliant Green (BG), Safranine O (SO) and Methylene Blue (MB)) using air as the sole oxidant in aqueous solution. Au-Pd(1:1)/NM-400 with an Au/Pd mass ratio of 1:1 calcined at 400 °C possessed the highest catalytic activity compared to the catalysts with other Au/Pd mass ratios and the monometallic catalysts due to the synergistic effect of Au and Pd. It could be workable efficiently for high dye concentrations at reaction temperatures even close to 0 °C. Dye degradation kinetics investigation shows that dye degradation follows pseudo-first-order kinetics. High dye removal efficiency still could be achieved after five times reuse which indicated that it exhibited a good reusability and catalytic stability. The mechanism investigation for catalytic activity revealed that superoxide radical (O2−) is the main active oxidative specie during CWAO of dyes.

Novel synthesis of nano needle-like Cu2O-GO-TiO2 and CuO-GO-TiO2 for the high photocatalytic performance of anionic and cationic pollutants

Novel nano needle-like Cu2O-GO-TiO2 (Cu2OGT-A) and CuO–GO-TiO2 (CuOGT-B) composites with superior photocatalysis were successfully synthesized via a self-assembly process at a low temperature. The structural and morphological characterizations of the synthesized compounds were analyzed using a series of analytical techniques. The photocatalyst showed excellent activity under visible light and was used for the photodegradation of safranine O (SO), reactive black B (RBB), and gallic acid (GA) as target anionic and cationic pollutants. The removal capacity of CuOGT-B is slightly higher than that of Cu2OGT-A, and the removal rates of SO, RBB, and GA reach up to 82.91%, 81.51%, and 83.87%, respectively. Furthermore, the excellent morphologies of Cu2OGT-A and CuOGT-B composites, e.g., needle-like structure, monodisperse, and graphene sheets drastically improve their dispersion in solution, light harvesting, charge separation and transportation, which might do some contributions to improve their photocatalytic activities accordingly. The Cu2OGT-A and CuOGT-B prepared under the conditions reported herein could be promising materials in water purification.

A Comparative Study on the Photophysical and Photochemical Properties of Dyes in the Presence of Low Generation Amino-terminated Polyamidoamine Dendrimers.

The photophysical and photochemical properties of the xanthene dyes mercurochrome (MCr) and eosin-Y (Eos); and the phenazine dye safranine-O (SF) are evaluated in the presence of amino-terminated polyamidoamine (PAMAM) dendrimers of low generations. The dendrimers produce a red shift in the UV-vis absorption spectra of the dyes, which increases with concentration and the size of the PAMAM molecule. The Stern-Volmer plots of fluorescence quenching for xanthenic dyes present a downward curvature. It is ascribed to a static mechanism involving a dye-dendrimer binding. A non-linear fitting of the SV plots allows the calculation of the binding constants. For SF, the fluorescence is only slightly quenched by PAMAMs and the SV plots are linear. The binding constants are in the order Kbind (SF) ≪ Kbind (Eos) < Kbind (MCr). The difference must be due to important specific structural effects. A decrease in the triplet lifetime and an increase in the absorption of the semireduced form of the dyes are observed in the presence of dendrimers. While for the two xanthene dyes, the rate constants reach the diffusional limit for G2 and G3, for SF they are one order of magnitude lower. This is explained by a different quenching mechanism of the two types of dyes.

Clay induced changes in the aggregation pattern of Safranine-O in hybrid Langmuir-Blogdgett (LB) films

Abstract In the present communication, detailed investigation has been carried out to study the clay mineral induced changes in aggregation of a well known cationic fluorescent dye Safranine-O (SO) in aqueous solution as well as in organo-clay hybrid Langmuir-Blodgett (LB) films. At higher dye concentration in aqueous solution, Safranine-O (SO) formed both H-dimers and J-aggregates and the corresponding UV–vis absorption spectra got distorted with increasing solution concentration. In clay mineral Laponite dispersed aqueous solution SO formed J-aggregates with increasing Laponite concentration resulting in an increase in fluorescence intensity. H-dimeric sites were also sufficiently decreased in organo-clay hybrid LB films of SO. UV–vis absorption and fluorescence spectroscopic as well as in-situ Brewster Angle Microscopic (BAM) studies were employed in our investigation.

Ternary self-assembly method of mesoporous silica and Cu 2 O combined graphene composite by nonionic surfactant and photocatalytic degradation of cationic-anionic dye pollutants

Abstract A facile and eco-friendly self-assembly method for combining mesoporous silica with Cu 2 O-graphene composite with a nonionic surfactant Pluronic® P123 is proposed. The achieved nanocomposites were characterized via X-ray diffraction (XRD), nitrogen adsorption/desorption isotherms using the BET and BJH method, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (UV–vis DRS), X-ray photoelectron spectroscopy (XPS), and FT-IR spectra. The photocatalytic degradation of safranine O (SO), texbrite BA-L (TBA), texbrite NFW-L (TNFW), and texbrite BAC-L (TBAC) organic dyes in an aqueous solution under visible light irradiation with the difference of initial pH and catalyst dosage was observed via UV spectrophotometry, after measuring the decrease in their concentrations. Two factors of the excellent photocatalytic activity of the mesoporous SiO 2 /Cu 2 O-graphene composite made a significant impression: the adsorption capacity due to the mesoporous structure (a result of the pore diameter, pore volume, and large surface area), and the decomposition effect through catalysis. Recycling experiments that were also carried out proved the good stability of the survey samples. The combination of mesoporous SiO 2 with 10% Cu 2 O-graphene nanocomposite (by weight) is expected to become a new generation material for photodegradation with excellent performance.

Acrylic microspheres-based optosensor for visual detection of nitrite

A new optosensor for visual quantitation of nitrite (NO2−) ion has been fabricated by physically immobilizing Safranine O (SO) reagent onto a self-adhesive poly(n-butyl acrylate) [poly(nBA)] microspheres matrix, which was synthesized via facile microemulsion UV lithography technique. Evaluation and optimization of the optical NO2− ion sensor was performed with a fiber optic reflectance spectrophotometer. Scanning electron micrograph showed well-shaped and smooth spherical morphology of the poly(nBA) microspheres with a narrow particles size distribution from 0.6μm up to 1.8μm. The uniform size distribution of the acrylic microspheres promoted homogeneity of the immobilized SO reagent molecules on the microspheres’ surfaces, thereby enhanced the sensing response reproducibility (<5% RSD) with a linear range obtained from 10 to 100ppm NO2− ion. The micro-sized acrylic immobilization matrix demonstrated no significant barrier for diffusion of reactant and product, and served as a good solid state ion transport medium for reflectometric nitrite determination in food samples.

Application of ultrasonic radiation for simultaneous removal of auramine O and safranine O by copper sulfide nanoparticles: Experimental design

In this study, copper sulfide nanoparticles loaded on activated carbon (CuS-NP-AC) were synthesized by novel, low cost and green approach and characterized using SEM and XRD. The application of this material for the simulations removal of auramine O (AO) and safranine O (SO) from aqueous solutions was investigated. The dependency of removal percentages to variables such as pH, initial dyes concentration, adsorbent dosage, sonication time and sonication temperature were studied with response surface methodology (RSM) by considering the desirability function (DF). The quadratic model between the dependent and the independent variables was built. The proposed method showed good agreement between the experimental data and predictive value, and it has been successfully employed to removal of AO and SO in aqueous media. The studied adsorbent (0.06g of CuS-NP-AC) was capable of high percentage removal (99.8% and 99.5%) of 18mgmL−1 AO and SO in short time (7.0min).

Silver(I) Catalyzed Photochemical Oxidation of Methylene Blue and Safranine-O by Peroxydisulphate: A Green Chemical Approach

In the present investigation, a comparative study of silver(I) catalysed photochemical oxidation of methylene blue (MB) and safranine-O (SO) by peroxydisulphate has been reported. The effect of different parameters, such as pH, concentration of peroxydisulphate, silver nitrate, and light intensity, on the reaction rate has been observed. The progress of the photochemical oxidation was monitored spectrophotometrically. The optimum conditions for photochemical oxidation were achieved. The dyes were completely oxidized and degraded into CO2 and H2O. A tentative mechanism for silver(I) catalyzed photochemical oxidation of these dyes by peroxydisulphate has also been proposed.

Cationic dye adsorption onto natural and synthetic zeolites in the presence of Cs+ and Sr2+ ions

Adsorption of diazine dye safranine O (SO) in the presence of Cs+ and Sr2+ ions was investigated onto natural and synthetic zeolites in order to predict competition of cationic organic species with their radionuclides, which are the main fission products released into the environment. Adsorption of SO was measured up to the 40th day and the surface-diffusion coefficients (Ds) were estimated by applying Nernst–Planck approximation based on a homogeneous-surface-diffusion model. The values of Ds were 10 times higher on natural zeolite than those of synthesized zeolite from fly ash (FA) under hydrothermal conditions. Similarly, distribution coefficients (KD) were considerably higher on the clinoptilolite-type natural zeolite. The zeolitized product of FA is mainly composed of analcime and sodalite. SO adsorption on natural zeolite was not influenced by Cs+ and Sr2+ ions, but it decreased at high concentrations on synthetic zeolite. The higher influence of the Sr2+ ions on SO+ adsorption showed that they compete with each other for the same adsorption sites. These results suggested that natural zeolite cannot be used for remediation of wastewater polluted with Cs and Sr radionuclides in the presence of organic cations, whilst FA zeolite has a potential for Sr removal.

Experimental design based response surface methodology optimization of ultrasonic assisted adsorption of safaranin O by tin sulfide nanoparticle loaded on activated carbon

In this research, the adsorption rate of safranine O (SO) onto tin sulfide nanoparticle loaded on activated carbon (SnS-NPAC) was accelerated by the ultrasound. SnS-NP-AC was characterized by different techniques such as SEM, XRD and UV–Vis measurements. The present results confirm that the ultrasound assisted adsorption method has remarkable ability to improve the adsorption efficiency. The influence of parameters such as the sonication time, adsorbent dosage, pH and initial SO concentration was examined and evaluated by central composite design (CCD) combined with response surface methodology (RSM) and desirability function (DF). Conducting adsorption experiments at optimal conditions set as 4min of sonication time, 0.024g of adsorbent, pH 7 and 18mgL−1 SO make admit to achieve high removal percentage (98%) and high adsorption capacity (50.25mgg−1). A good agreement between experimental and predicted data in this study was observed. The experimental equilibrium data fitting to Langmuir, Freundlich, Tempkin and Dubinin–Radushkevich models show that the Langmuir model is a good and suitable model for evaluation and the actual behavior of adsorption. Kinetic evaluation of experimental data showed that the adsorption processes followed well pseudo-second-order and intraparticle diffusion models.

Comparison of Activated Carbon, Multiwalled Carbon Nanotubes, and Cadmium Hydroxide Nanowire Loaded on Activated Carbon as Adsorbents for Kinetic and Equilibrium Study of Removal of Safranine O

ABSTRACT Activated carbon (AC), multiwalled carbon nanotube (MWCNT), and cadmium hydroxide nanowire loaded on activated carbon (Cd(OH)2-NW-AC) have been used for the removal of safranine O (SO) from wastewater. The effects of various parameters including pH, temperature, concentration of the dye, amount of adsorbents, and contact time on the SO adsorption efficiency for all adsorbents has been investigated. Graphical correlation of fitting experimental data to various adsorption isotherm models like those of Langmuir, Freundlich, Tempkin, and Dubinin–Radushkevich for all adsorbents have been calculated. It was found that safranine O adsorption on all adsorbents was endothermic and feasible in nature. Fitting the experimental data to different kinetic models suggests that the adsorption process follows pseudo-second-order kinetics with involvement of the particle diffusion mechanism.

Spontaneous adsorption and electrochemical behaviour of safranine O at electrochemically activated glassy carbon electrode

The adsorption behaviour of safranine O (SO) at electrochemically pretreated glassy carbon electrodes has been studied. It was found that SO adsorption depended on the properties of the electrode surface, as determined by the nature and duration of the activation step. It was noticed that SO was adsorbed spontaneously and strongly on the surface of anodically pretreated electrode. The electrochemical behaviour of the modified electrode was investigated in H 2SO 4 (0.25 M) using cyclic voltammetry (CV). A reversible two electron, two proton wave was observed at −180 mV vs. SCE and the formal potential was found to be decreasing upon increasing the solution pH (−56.8 mV pH −1). The modified electrode exhibited good stability on repeated scanning between −500 and 200 mV vs. SCE, causing only 5% decrease in the peak height after 100 cycles at a scan rate of 20 mV s −1. The surface coverage was calculated to be 0.812 nmol cm −2 and the electron transfer rate constant ( k s 0 = 1.45 s − 1 ) and transfer coefficient ( α = 0.43) for the adsorbed SO were evaluated using the Laviron method. The modified electrode clearly showed good electrocatalytic ability for oxygen reduction to H 2O 2.