Alizarin Red S Concentration Research Articles

Auto recalibration based on dual-mode sensing for robust optical continuous glucose monitoring

Boronic acid based optical continuous glucose monitoring systems (CGMs) hold promise for long-term glucose monitoring. However, these sensors suffer drifts induced inaccuracy and external calibration. One of the reasons is the denature of boronic acid structures and optical reporters. To solve this problem, a dual-mode glucose sensing method with auto-recalibration capabilities is developed using glucose-selective diboronic acid molecule (DBA) and optical reporter alizarin red S (ARS). DBA binds ARS at a 1:2 ratio and produces distinct changes in both the absorbance (Abs) and the fluorescence (FL) spectra of ARS. Through competitive binding with DBA, glucose induces a compensatory shift in both Abs and FL signals. The two signals were demonstrated to be strongly correlated and were combined to build Abs-FL-glucose 3D calibration curves for glucose determination. The mapping relationship of two signals drift closely with both changes of DBA and ARS concentration. By ascertain the right mapping relationship, the two strongly correlated signals can alert undesirable degradation of sensing components, identify the correct calibration curve, and accurately predict glucose concentration without external calibration. The introduction and adoption of the auto-recalibrating dual-mode sensing strategy could constitute a useful development in the pursuit of next generation long-term calibration-free CGM and wearable sensors technologies with superior precision.

A novel and efficient voltammetric sensor for the simultaneous determination of alizarin red S and tartrazine by using poly(leucine) functionalized carbon paste electrode

In the current work, a rapid, selective, and sensitive technique was developed for the detection of Alizarin Red S (ARS) by applying poly leucine modified carbon paste electrode (PLMCPE). Electrochemical impedance spectroscopy (EIS) and Scanning electron microscopy (SEM) were utilized to study the surface morphology of unmodified carbon paste electrode (UMCPE) and PLMCPE. The active surface area for UMCPE and PLMCPE was found to be 0.0012 cm2 and 0.0026 cm2 respectively. The electrochemical response of ARS at UMCPE and PLMCPE was analyzed using cyclic voltammetry (CV) in the potential window of 0.4 to 1.0 V. The cyclic voltammogram obtained for varying the pH of 0.2 M phosphate buffer (PB) solution showed maximum current for the oxidation of ARS at pH 6.5. The electrochemical reaction of ARS was found to be irreversible and adsorption controlled. The effect of variation of concentration of ARS on the oxidation peak current was evaluated using CV and linear scan voltammetry (LSV). A linear relationship between the concentration variation and current was obtained in the linear range of 1.5 μM–3.5 μM and 0.2 μM–5.0 μM for CV and LSV respectively. The limit of detection (LOD) of 0.68 μM for the CV method and 0.29 μM for the LSV method was exhibited by the developed sensor. The simultaneous study of ARS along with tartrazine (TZ) showed good selectivity for ARS. The interferents of foreign molecules showed no effect on the selectivity of the electrode. The applicability of PLMCPE on real samples gave good recovery ranging from 97.46–101.2%; hence, the sensor can be utilized on real samples. The developed sensor has good stability and sensitivity.

Optimizing the mass marking of fish with alizarin red S: an example with glass eels.

Fish marking is an essential tool for fisheries management, especially for evaluating the stocking of endangered fish species to support conservation and sustainable use of fish stocks. Batch marking of young European eels Anguilla anguilla (L.) prior to stocking is recommended as the benefits of stocking for the spawning stock can be evaluated by recapturing marked fish over time, therefore mass marking of young eels with substances such as alizarin red S (ARS) is becoming increasingly important. To improve the marking method and reduce marking costs when immersing glass eels in an ARS solution, eight laboratory experiments under varying conditions (e.g., temperature, ARS concentration, immersion time, osmotic induction, fish density) and with ARS from different suppliers were carried out. The results show that optimal marking of glass eels can be carried out in the field or during transport by putting approximately 50 g of glass eels per liter in 150 mg L-1 ARS solution for 3 h at 10-15°C. Lower concentrations did not result in reliable marking. Water temperatures of 5°C and below can have a stunning effect on the eels and increase mortality significantly, regardless of the concentration of ARS. Glass eel densities below 50 g L-1 in the marking bath increase marking costs unnecessarily, while a higher density of 100 g L-1 resulted in significantly higher mortality and lower marking success. A somewhat more difficult but less expensive alternative is to bathe the fish in a saline solution of 1% (10 PSU) of 80 mg L-1 ARS for 3 h at 10°C. Costs can also be significantly reduced by choice of supplier for ARS, but care should be taken as the quality of the powder appears to vary (mean percentage of sufficiently marked eels ranged from 59% to 91% among suppliers in the present study) and can lead to marking failure. The optimal marking conditions can help ensure that stocked glass eels can be reliably identified in future studies to assess stocking benefits while reducing costs.

Porous silica composites as efficient adsorbents for dye removal from aqueous solution

This study aimed to analyze the feasibility of removing Alizarin red S (ARS) used as model pollutant from aqueous solutions using the preparative porous silica composites (PSCs) as adsorbents which were prepared via hydrothermal approach. The physicochemical properties of materials were characterized by means of Transmission electron microscope (TEM), Scanning electron microscope (SEM), Energy dispersive spectrometer (EDS), Brunauer-Emmett-Teller (BET) method, Barret-Joyner-Halenda (BJH) method, Fourier Transform Infrared Spectrometer (FTIR) and X-Ray Diffractometer (XRD). PSCs possessed the specific surface area were 731.6 m2/g, 420.9 m2/g, 294.6 m2/g, respectively. The presence of silica structures was confirmed by FTIR spectra. In order to confirm efficiency of composites as adsorbents and reveal adsorption mechanism, the impacts of pH, contact time, initial ARS concentration, temperature on adsorption were conducted. The adsorption experiment results showed that the adsorption efficiency of ARS onto PSC-3 was better than that of PSC-1 and PSC-2 at pH = 11. Furthermore, the adsorption kinetic models, isotherm models and thermodynamic model were analyzed for comprehensive adsorption process. The maximum adsorption capacity of PSC-3 for ARS was 43.1 mg/g. The pseudo-second-order kinetic model and Sips isotherm model were more suitable for experimental results. The adsorption process was endothermic according to the adsorption thermodynamic model. The free energy of adsorption required for ARS onto PSCs was less than 8 kJ/mol, indicating physical adsorption. What’s more, PSC-3 possessed advantages of higher adsorption capacity and shorter equilibration time. Overall, these results made it potentially applicable as an effective adsorbent for ARS dye from effluent.

Removal of Alizarin red S by calcium-terephthalate MOF synthesized from recycled PET-waste using Box-Behnken and Taguchi designs optimization approaches

In this research, recovered terephthalic acid from polyethylene terephthalate (PET) waste was employed as a precursor for the high yield solvothermal synthesis of a calcium-terephthalate metal-organic framework ([Ca(BDC) (H2O)3]). The structure of this MOF was analyzed using FTIR, XRD, BET, EDX, and FESEM methods. For the first time, its adsorption ability was studied to remove Alizarin red S (ARS) dye from an aqueous solution. Experimental designs involving Box-Behnken (BBD) and Taguchi were used to optimize removal conditions. These two approaches were compared for optimization of the adsorption process. So, effective factors such as pH, adsorbent dosage (m), and initial ARS concentration (C) were examined. BBD with 15 runs led to a proper relation between the effective factors and either removal percent (R%) or adsorption capacity (q) response. The proposed BBD model yielded a maximize removal percent (R% ​= ​69.97) and adsorption capacity (q ​= ​788.3 ​mg˖g−1) of ARS for following optimum conditions: pH ​= ​6, m ​= ​2 ​mg, and C ​= ​379 ​mg˖L−1. The optimum conditions obtained by a Taguchi design with 9 runs are pH ​= ​5, m ​= ​2 ​mg, and C ​= ​300 ​mg˖L−1. The adsorbent-adsorbate behavior is described by the Langmuir-Freundlich isotherm model well because this isotherm has the largest value of nonlinear R2 (R2 ​= ​0.9966) form compared with others. The maximum adsorption capacity (qmax) of ARS is 979.0 ​mg∙g−1. The experimental data obey the pseudo-second-order (PSO) kinetic model (R2 ​= ​0.9702). According to the negative value of ΔH° (−13 ​kJ ​mol−1), ΔS° (−0.037 ​kJ∙mol−1), and ΔG° (−2.6 to −1.5 ​kJ∙mol−1), the ARS adsorption process is exothermic and spontaneous chemisorption in the thermal range of 293–323 ​K.

The biosorption of Alizarin Red S by Spirulina platensis; process modelling, optimisation, kinetic and isotherm studies

ABSTRACT Spirulina platensis is abundant biomass of cyanobacteria (blue-green algae) which is applied in the current study as a biosorbent. A statistical Box–Behnken approach was adopted to remove the toxic dye of alizarin red S (ARS) from synthetic solutions. A polynomial equation was developed to predict the dye removal efficiency and elucidate the interaction effects of variables. The maximum removal efficiency of ARS (69.1%) was obtained at pH 6.5, mixing time of 42.5 min, dye concentration of 100 mg. L−1 and S. platensis dose of 1.5 g. L−1. The findings indicated that the biosorption rate of ARS had a direct relationship with the ARS concentration, pH, reaction time, and S. platensis dose. The quadratic model suggested that the ARS concentration is the major variable in ARS removal. The isotherms and kinetics data could be suitably reflected by the Langmuir model and the pseudo-first-order equation. The maximum adsorption capacity of S. cerevisiae was obtained to be 17.15 mg. g−1 based on the Langmuir model. The results showed that the removal rates of ARS from the first cycle up to the fourth cycle were varied from 55% to 20%, respectively. In conclusion, S. platensis shows suitable adsorptive characteristics and hence could be suggested as a viable option for future studies.

Photocatalytic activity of G-TiO2@Fe3O4 with persulfate for degradation of alizarin red S under visible light

A composite photocatalyst combined with TiO2, graphite (G) and Fe3O4 was prepared by co-precipitation method. Then the G-TiO2@Fe3O4 was employed with persulfate (PS) to degrade alizarin red S (ARS) under visible light. The removal rate of ARS reached 100% after 60 min irradiation. The degradation rate constant of G-TiO2@Fe3O4/PS exhibited 20.8, 9.0 and 3.1 times than that of TiO2, G-TiO2 and G-TiO2@Fe3O4, respectively. The effects of photocatalyst dosage, mass ratios of graphite and Fe3O4 to TiO2, PS dosage, initial pH and ARS concentration on the degradation efficiency were investigated. The optimal removal efficiency of ARS was obtained when G-TiO2@Fe3O4 dosage was 0.25 g/L, G: TiO2 = 0.005, Fe3O4: TiO2 = 0.8, PS concentration was 6 mmol/L, initial pH = 3, and initial concentration of ARS was 100 mg/L. The SO4·- was demonstrated more important than O2− and·OH in the degradation of ARS. The intermediates and possible degradation pathways of ARS were discussed. Reuse and stability of G-TiO2@Fe3O4 were also tested, and 88.3% photocatalytic activity was maintained after five cycles. Therefore, the proposed G-TiO2@Fe3O4/PS not only had excellent photocatalytic activity, but also showed superior stability and reusability.

Cyclic Sequential Removal of Alizarin Red S Dye and Cr(VI) Ions Using Wool as a Low-Cost Adsorbent

Alizarin red S (ARS) removal from wastewater using sheep wool as adsorbent was investigated. The influence of contact time, pH, adsorbent dosage, initial ARS concentration and temperature was studied. Optimum values were: pH = 2.0, contact time = 90 min, adsorbent dosage = 8.0 g/L. Removal of ARS under these conditions was 93.2%. Adsorption data at 25.0 °C and 90 min contact time were fitted to the Freundlich and Langmuir isotherms. R2 values were 0.9943 and 0.9662, respectively. Raising the temperature to 50.0 °C had no effect on ARS removal. Free wool and wool loaded with ARS were characterized by Fourier Transform Infrared Spectroscopy (FTIR). ARS loaded wool was used as adsorbent for removal of Cr(VI) from industrial wastewater. ARS adsorbed on wool underwent oxidation, accompanied by a simultaneous reduction of Cr(VI) to Cr(III). The results hold promise for wool as adsorbent of organic pollutants from wastewater, in addition to substantial self-regeneration through reduction of toxic Cr(VI) to Cr(III). Sequential batch reactor studies involving three cycles showed no significant decline in removal efficiencies of both chromium and ARS.

Evaluation of the bioaccumulation potential of alizarin red S in fish muscle tissue using the European eel as a model.

For fish stock management and large-scale stocking programs, the chemical substance alizarin red S (ARS) is an important tool to mark fish permanently. Equally, for the IUCN red list species European eel (Anguilla anguilla), ARS is proven to be the most promising option for mass marking. ARS binds to calcified structures (i.e., bones and otoliths) and can be detected using a fluorescence microscope. Despite the frequent application of ARS, not only for eels but also for fish in general, until today, no study has evaluated its bioaccumulation potential. Therefore, the German Federal Risk Assessment Authority was unable to classify ARS as harmless because of a potential risk to consumers' health. Using the technique of liquid chromatography mass spectrometry, an ARS detection protocol was developed and the bioaccumulation potential of ARS in European eel muscle tissue was estimated. A detection limit of 8.9μgkg-1 could be reached by optimizing the detection method in fish muscle tissue. In the current study, 250 eels between 6 and 57cm of total length have been analyzed for ARS between 0day and 3years after the marking process. The highest concentration of ARS (6056μgkg-1) was observed immediately after marking in the smallest length class. Only 1year after the marking procedure, the ARS concentration was below detection limit. A new method for ARS detection in fish muscle tissue, followed by utilization on marked eels, was able to show that the bioaccumulation of ARS in edible fish muscle was highly unlikely.

Electrochemical Sensor for the Determination of Alizarin Red-S at Non-ionic Surfactant Modified Carbon Nanotube Paste Electrode

The Cyclic Voltammetric (CV) behavior of Alizarin Red-S (ARS), which is an Anthraquinone dye was examined by utilizing TX-100 modified carbon nanotube paste electrode (TX-100MCNTPE). The surfactant utilized is TX-100, and it has been found that it has good electrocatalytic activity towards ARS. Distinctive parameters like pH, scan rate, detection limit have been studied in the potential range of 0.4 V to 1.0 V by using 0.2 M phosphate buffer solution (PBS) as supporting electrolyte. From these studies, it was clear that ARS shows well characterized irreversible oxidation peak in the solution of pH 6.5 at a scan rate of 0.1 V/s. Scan rate studies reveal that the entire process is adsorption controlled. Oxidation peak current rises linearly with the increase in the concentration of ARS. Two linear range is observed in the array of 2 × 10-6 to 10 × 10-6 M and 15 × 10-6 to 35 × 10-6 M. First linear range with a limit of detection (LOD) and limit of quantification (LOQ) of 1×10-6 and 3×10-6 M respectively was considered. The fabricated sensor can be productively employed for the simultaneous determination of ARS and Tartrazine (TZ).

RAPID SPECTROPHOTOMETRIC METHOD FOR HISTAMINE DETERMINATION IN FISH USING ALIZARIN RED S AND METAL

An analytical method for the determination of histamine using metals and alizarin red S (ARS) reagents by UV-Visible spectrophotometry was developed. Cu(II), Co(II) and ARS were used to form colored complex with histamine. The developed method was used to detect qualitatively and quantitatively the presence of histamine. Absorbance of Cu(II) and Co(II) complex were measured at a maximum wavelength of 505.5 and 567 nm, respectively. Optimization of analytical parameters such as concentration of metals, concentration of ARS, sample solution pH, and optimum time for complex formation were performed. Experimental results showed that the optimum concentration of Cu(II) was 50 ppm, 75 ppm ARS, sample solution pH 6, and 15 minutes optimum time, while the optimum concentration of Co(II) was 125 ppm, ARS was 75 and 50 ppm, sample solution pH 5 and 10 minutes optimum time. Method validation indicated that the coefficient of variation, limit of detection (LOD) (S/N =3), and limit of quantitation (LOQ = 10S/N) of Cu(II) were 0.65%, 8.94 ppm, and 29.82 ppm respectively with a sensitivity of 0.0054 ppm and linearity of 0.9959. Accuracy of histamine determination through Cu-ARS-histamine complex at a concentration of 50, 100, and 150 ppm were 105.7% (RSD = 0.777%, n = 3), 105.06% (RSD = 0.606%, n = 3), and 94.12% (RSD = 0.767%, n = 3), respectively. Meanwhile, the CV, LOD, and LOQ of Co(II) were 0.28%; 2.58 ppm; and 8.6 ppm respectively with a sensitivity of 0.0006 ppm and linearity of 0.9965. Accuracy of histamine determination through Co-ARS-histamine complex at a concentration of 50, 75, and 125 ppm were 98.33%, 95.83%, 93.88%, respectively. The proposed method was successfully applied to the determination of histamine in a fish sample with quantitative recovery; for Cu(II) complex (99.23%) and Co(II) complex (102.62%).

Electrochemical Studies on Alizarin Red S as Negolyte for Redox Flow Battery: a Preliminary Study

Redox flow battery (RFB) has received tremendous attention as energy storage system coupled with renewable energy sources. In this paper, a low-cost alizarin red S (ARS) organic dye is proposed to serve as the active material for the negative electrode reaction for organic redox flow batteries. Cyclic voltammetry has been conducted under a number of operating conditions to reveal the electrochemical performance of this molecule. The results suggest that ARS is highly reversible at low electrode potential (c.a. 0.082 V vs. standard hydrogen electrode), indicating that ARS is a promising negative electrode material for organic redox flow batteries. The diffusion coefficient of ARS is calculated in the range of 6.424 x 10-4 cm2 s-1, This has indicated fast diffusion rate and electrochemical kinetics for oxidation and reduction in higher concentration of ARS. It has been found out that the higher concentration of ARS in base electrolyte cause lowest diffusion coefficient due to solubility issue of ARS.

Cationic Surfactant-modified Clay as an Adsorbent for the Removal of Synthetic Dyes from Aqueous Solutions

AbstractIn this study, the potential of hexadecyl trimethyl ammonium bromide modified montmorillonite (HDTMA-Mt) to remove the synthetic dyes Alizarin Red S (ARS) and Bromocresol Green (BCG) from aqueous media was assessed. The effect of different factors including surfactant loading rate onto the clay, contact time, pH, adsorbent dosage and dye concentrations, on the removal of ARS and BCG in batch systems were investigated. The adsorbent was characterized by means of scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometry (XRD). The equilibrium time for ARS and BCG was reached at 40 and 20 min, respectively, under optimized conditions (i.e. pH = 3, adsorbent dosage=1 g/L, surfactant loading rate onto the clay 70% of the cation exchange capacity (CEC) for ARS and 120% of the CEC for BCG, ARS concentration 50 mg/L and BCG concentration 500 mg/L). The adsorption rate of both dyes fitted the pseudo-second-order kinetic model and the equilibrium data was described by the Freundlich isotherm equation. The maximum monolayer adsorption capacities were equal to 666.6 and 1250 mg/g for ARS and BCG, respectively. Therefore, the HDTMA-Mt can be considered as an effective adsorbent for the removal of ARS and BCG from aqueous solutions.

Adsorption property of alizarin red S by NiFe2O4/polyaniline magnetic composite

NiFe2O4/polyaniline (PANI) magnetic composite was prepared by in situ chemical oxidative polymerization of aniline in the presence of NiFe2O4 particles, where the NiFe2O4 particles were synthesized by a facile hydrothermal method. The magnetic composite was characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Brunauer-Emmett-Teller (BET) surface area method and vibrating sample magnetometer (VSM) techniques. The adsorption characteristics of the NiFe2O4/PANI composite were assessed by using alizarin red S (ARS) as an adsorbate. The adsorption process was investigated as the function of ionic strength, temperature, solution pH, adsorbent dosage, contact time and initial ARS concentration. The equilibrium adsorption data fitted well to the Langmuir model and the maximum adsorption capacity was found to be 186 mg g−1 at 303 K. The remarkable adsorption capacity of ARS onto NiFe2O4/PANI was attributed to stronger π-π interaction and weak electrostatic attraction between ARS and NiFe2O4/PANI.Kinetic studies indicated that ARS adsorption followed the pseudo-second-order kinetic model. The whole adsorption process was jointly controlled by external mass transfer and intraparticle diffusion. Thermodynamic parameters (ΔG°, ΔH° and ΔS°) revealed that the adsorption of ARS on the NiFe2O4/PANI composite was a spontaneous and endothermic process. Magnetic NiFe2O4/PANI with adsorbed ARS could be regenerated using basic ethanol solution and was separable from liquid media using a magnetic field.

Mass-marking of farmed European eels (Anguilla anguilla (Linnaeus, 1758)) with alizarin red S

The Working Group on Eel of the International Council for the Exploration of the Sea (ICES) regularly reports that a significant amount of stocked eels in Europe was pre-grown in aquaculture farms prior to stocking—so called “farmed eels.” The ICES advices chemical marking of stocked recruits to ensure their traceability throughout all life stages. To date, however, there was a lack of knowledge concerning the most suitable chemical substance and its application on farmed eels. The aim of this study was to fill this gap by presenting successful attempts of marking those eels with alizarin red S (ARS). An ARS concentration of 150 mg L−1 buffered with 150 mg L−1 Tris(hydroxymethyl)aminomethane applied as an immersion bath over 9 h was sufficient to mark a total of 3572 kg of farmed eels (6.5–8.0 g mean body weight). The marking success was 100% on otoliths and highest stocking density of up to 67.1 kg m−3 (corresponding 54.0 kg m−2) turned out to have no effect on mortality which was consistently below 1%.

A Self-Assembled Sensor for Carbohydrates on the Surface of Cyclodextrin Vesicles.

A supramolecular carbohydrate sensor was prepared by self-assembly of unilamellar bilayer vesicles of amphiphilic β-cyclodextrin with a boronic acid-adamantane conjugate (PBA-AD), which binds strongly to β-cyclodextrin through host-guest interactions (Ka ≈4×104 m-1 ), so the vesicle surface exhibits multiple boronic acid receptors for carbohydrates. The binding of diols to the functionalized vesicles was tested with alizarin red S (ARS) as a reporter dye by using fluorescence and UV/Vis spectroscopy. Analysis of the competitive binding of monosaccharides revealed pH-dependent (pH 7.4-10.1) binding constants in the range of 100-3000 m-1 for d-fructose and 5-400 m-1 for d-glucose. Interestingly, the self-assembled sensor showed fluorescence intensity enhanced by about fivefold and a binding affinity to the reporter dye increased by about eightfold in comparison to PBA-AD and ARS without vesicles. This is attributed to increased local concentration of ARS and PBA-AD on the surface of the vesicles. Detection of d-fructose and d-glucose was possible in the physiologically relevant range in dilute aqueous solution.

Revisiting in vivo staining with alizarin red S--a valuable approach to analyse zebrafish skeletal mineralization during development and regeneration.

BackgroundThe correct evaluation of mineralization is fundamental for the study of skeletal development, maintenance, and regeneration. Current methods to visualize mineralized tissue in zebrafish rely on: 1) fixed specimens; 2) radiographic and μCT techniques, that are ultimately limited in resolution; or 3) vital stains with fluorochromes that are indistinguishable from the signal of green fluorescent protein (GFP)-labelled cells. Alizarin compounds, either in the form of alizarin red S (ARS) or alizarin complexone (ALC), have long been used to stain the mineralized skeleton in fixed specimens from all vertebrate groups. Recent works have used ARS vital staining in zebrafish and medaka, yet not based on consistent protocols. There is a fundamental concern on whether ARS vital staining, achieved by adding ARS to the water, can affect bone formation in juvenile and adult zebrafish, as ARS has been shown to inhibit skeletal growth and mineralization in mammals.ResultsHere we present a protocol for vital staining of mineralized structures in zebrafish with a low ARS concentration that does not affect bone mineralization, even after repetitive ARS staining events, as confirmed by careful imaging under fluorescent light. Early and late stages of bone development are equally unaffected by this vital staining protocol. From all tested concentrations, 0.01 % ARS yielded correct detection of bone calcium deposits without inducing additional stress to fish.ConclusionsThe proposed ARS vital staining protocol can be combined with GFP fluorescence associated with skeletal tissues and thus represents a powerful tool for in vivo monitoring of mineralized structures. We provide examples from wild type and transgenic GFP-expressing zebrafish, for endoskeletal development and dermal fin ray regeneration.

Kinetics of decolorization of Alizarin red S in aqueous media by Fenton-like Mechanism

The decolorization kinetics of Alizarin Red S (ARS) in aqueous solution was studied using Fenton like reaction in dark environment. The effects of dye, Ferric ions and hydrogen peroxide concentrations were investigated. The reaction was first order in ARS, H2O2 and zero order in ferric chloride. Increasing the hydrogen peroxide concentration (2-8 x10-3 mol dm-3) increases the rate constant from 1.05x10-3 to 3.2 x 10-3 s-1and excess of hydrogen peroxide shows no effect on the rate constant. Ferric ion concentration shows soft retardation effect on the degradation rate of ARS. Increasing the initial ARS concentration from 1 to 4x 10-4 mol dm-3decreases the decolorization from 85 % to 55 % within 15 minutes. Increasing temperature in the range of 298-313 K increases the rate of degradation and no optimal value detected. In addition, the influence of inorganic additives such, carbonate, nitrate and chloride on the efficiency of dye removal were examined.

Kinetic and equilibrium study of Alizarin Red S removal by activated carbon

Activated carbon has been applied for the adsorption of Alizarin Red S (ARS) from the waste water in a batch method to obtain high removal percentage. The influence of variables such as pH, temperature, ARS concentration, mass and size of adsorbent, and contact time on ARS removal percentage was investigated. Different kinetics, thermodynamics, and isotherm models were applied for fitting the experimental data. The adsorption process follows a pseudo second-order kinetic model with R 2 of 0.98 and Freundlich, Tempkin, and Dubinin-Radushkevich isotherm models with high determination coefficients (R 2) of 0.91, 0.98, and 0.98, respectively. High enthalpy (positive value), Gibbs free energy (negative value), and high entropy values shows the feasibility and the endothermic spontaneous nature of the removal process.

Anodic oxidation of anthraquinone dye Alizarin Red S at Ti/BDD electrodes

The boron-doped diamond (BDD) thin-film electrode with high quality using industrially titanium plate (Ti/BDD) as substrate has been prepared and firstly used in the oxidation of anthraquinone dye Alizarin Red S (ARS) in wastewaters. The Ti/BDD electrodes are shown to have high concentration of sp 3-bonded carbon and wide electrochemical window. The results of the cyclic voltammetries show that BDD has unique properties such as high anodic stability and the production of active intermediates at the high potential. The oxidation regions of ARS and water are significantly separated at the Ti/BDD electrode, and the peak current increases linearly with increasing ARS concentration. The bulk electrolysis shows that removal of chemical oxygen demand (COD) and color can be completely reached and the electrooxidation of ARS behaves as a mass-transfer-controlled process at the Ti/BDD electrode. It is demonstrated that the performances of the Ti/BDD electrode for anodic oxidation ARS have been significantly improved with respect to the traditional electrodes.