Discoloration Rate Research Articles

Crack Evaluation of Concrete Using Mechanochromic Sensor.

In this study, the deformation of concrete materials was evaluated using a mechanochromic sensor that detects the discoloration reaction caused by deformation. This sensor was attached by applying the Loctite adhesive to both ends in the longitudinal direction. The process of applying tensile stress to the specimens was videotaped, and the deformation and discoloration were examined through image analysis. The mechanochromic sensor was not affected by the finished surface condition, and the discoloration reaction was detected for a concrete material deformation level of up to 0.01 mm. The detected level was caused by the elongation of the sensor, and the discoloration compared with the initial color was identified. In addition, the integration behavior of the mechanochromic sensor under the deterioration of concrete members in cold areas and winter environments, as well as the discoloration reaction of the sensor in a low-temperature environment, was examined. It was found that the discoloration ability of the mechanochromic sensor exposed to a low-temperature environment was restored in 2 h after the end of the freeze-thaw test, and it was judged that the deformation and discoloration levels will be properly measured when the surface temperature of the sensor is restored to a room temperature of approximately 15 °C. This appeared to be due to the room temperature recovery of the dielectric spacer of the sensor and the deformation structure of the resonance condition. The sensor was also attached when diagonal cracks occurred in the concrete beam members to evaluate the strain and discoloration rate according to the deformation and discoloration levels. Accordingly, the cracks and deformation of the concrete materials were monitored using measured values from the discoloration of the mechanochromic sensors, and the possibility of measuring the crack width was reviewed only by real-time monitoring and imaging with the naked eye.

Development of a fully biocompatible and solid enzymatic-time-temperature indicator for cold chain system

Enzymatic-time-temperature indicators (ETTIs) present a discoloration with time and temperature based on an enzymatically decomposed reaction between starch, iodine and α-amylase. Although the ETTIs are highly eye-catchable and biocompatible, most of ETTIs have been demonstrated in a form of liquid phase, limiting the application in cold chain system due to the packaging issue. In this work, first we investigate the discoloration of ETTI in liquid phase and then we fabricate solidified ETTI using a gelatin. The discoloration of our ETTI is investigated at different temperatures room temperature, 4 °C and −24 °C for ambient, cold, frozen storages, respectively. As a result, the ETTI presents different rate of discoloration at different temperatures, showing the capability of TTI system. Since Our ETTI is able to indicate the wide range of time and temperatures through the discoloration and also it is solid and fully biocompatible, the ETTI can be potentially applied to cold chain system or storage indicators.

Experimental and theoretical study on photochromism of triphenylvinyl-naphthopyrans

A novel class of dual photo-responsive triphenylvinyl-naphthopyrans (TNPs) have been designed and synthesized by linking a triphenylvinyl fluorophore with the skeleton of 2H-naphthopyran. UV–vis absorption spectral experiments show that TNPs exhibit very rapid color changes and tunable thermal fading rates, which are controlled greatly by the electronic and steric effect of the triphenylene moiety and the 2-aryl rings. In addition, TNPs can emit strong blue fluorescence in aggregate state due to the restriction of intramolecular rotations. Theoretical calculation unveiled that the triphenylethylene moiety can regulate dynamically the photochromic and discoloration rates of TNPs. These findings will greatly promote the rational design and further development of new organic functional materials.

Exploration of the initial photocatalytic activity parameters of αFe2O3–rutile for methylene blue discoloration in water through the OFAT process

The photocatalyst response is related to experimental conditions that improve effectiveness in removing contaminants. A parameter analysis of αFe2O3–rutile and water contaminated with methylene blue (MB) was carried out to obtain initial factors that impact reaction conditions. Moreover, the following factors were tested: the αFe2O3–rutile load, the initial MB concentration, and the initial pH solution. These one-factor-at-a-time variations were made to explore the conditions of each variable with the other two fixed. Above all, a significant change was identified in the initial discoloration rate from 5.2 to 35.56 10−9 mol g−1 s−1, with 34 and 91 % removal effectiveness, respectively. These results were achieved with an αFe2O3–rutile load of 1.0 g L−1, an initial MB concentration of 8.0 10−6 mol L−1, and a pH of 8.8, after 540 min of irradiation. This high discoloration effectiveness with αFe2O3–rutile had not been previously reported. The parameter that most influenced the photocatalytic activity was the initial pH solution due to the interaction of the point of zero charge of αFe2O3–rutile and the contaminated water; the pH of the solution exceeds the isoelectric point, it causes electrostatic forces and hydrogen bonds with MB to increase its effectiveness. The combination of αFe2O3–rutile and the removal of methylene blue in water improves adsorption on the surface of the αFe2O3–rutile, providing the highest discoloration rate.

The Potential Function of SiLOX4 on Millet Discoloration during Storage in Foxtail Millet

Millet color is an important index for consumers to assess foxtail millet quality. The yellow color of millet is mainly because of the accumulation of carotenoids, which are essential for human nutrition. However, the discoloration of millet during storage due to carotenoid degradation seriously reduces the nutritional and commercial value of millet products. The essential quality traits of millet discoloration during storage were analyzed using two foxtail millet varieties, namely 9806-1 and Baomihunzi. We observed that the millet discoloration was caused by carotenoid degradation during storage, and different genotypes exhibited different discoloration rates. The carotenoid reduction rate in 9806-1 (32.2%) was higher than that in Baomihunzi (10.5%). The positive correlation between carotenoid reduction and the expression of SiLOX protein indicated that SiLOX from foxtail millet played a major role in carotenoid reduction during storage. The expression profiles of the SiLOX gene family were analyzed at different grain maturing stages, from S1 to S3, in these two varieties to determine the key SiLOX genes responsive to millet discoloration in foxtail millet. The consecutively low expression of SiLOX2, SiLOX3, and SiLOX4 contributed to the low level of SiLOX protein in Baomihunzi. Furthermore, the undetectable expression of SiLOX4 in the later stage of maturation in Baomihunzi was associated with low discoloration, indicating that SiLOX4 might be a key gene in regulating the discoloration of millet. This study provided critical information on the mechanism of carotenoid degradation during millet storage and laid the foundation for further understanding of carotenoid metabolism in foxtail millet.

Pressable lithium disilicate ceramic versus CAD/CAM resin composite restorations in patients with moderate to severe tooth wear: Clinical observations up to 13 years.

To report the long-term clinical survival and failure rates of single-tooth restorations made of pressable lithium disilicate ceramics (LS2 ) and CAD/CAM resin composite (RC) by two separate clinical observations. Twenty-one patients (12 female, nine male) were treated with 436 minimally invasive single-tooth restorations made of 274 pressed LS2 (n=12; posterior: monolithic IPS e.max Press; anterior: IPS e.max Ceram veneered, Ivoclar) or 162 milled from RC (n=9; monolithic exp. CAD/CAM resin composite, Ivoclar). The mean age of patients was 44.1 ± 9.3 years and the mean observation time was 86.2 ± 13.5months (7.7 ± 1.1 years), with 8.5 ± 2.7 years for LS2 and 6.7 ± 0.5 years for RC. All restorations were observed for technical/biological failures using the modified criteria of the United States Public Health Service (USPHS). Collected data were analyzed using Kaplan-Meier survival analysis and log-rank test (α < 0.025). The 274 LS2 restorations showed a survival of 100% and a total failure rate of 5.5%. The 162 RC restorations showed a survival of 100% and a total failure rate of 25.3%. RC restorations exhibited more material fractures (p=0.020) and higher discoloration rates (p < 0.001). Pressed LS2 single-tooth restorations showed lower long-term failure rates than restorations made of RC. Despite the limitations of the clinical observations, single-tooth restorations of both materials can be recommended for permanent use in patients with severe tooth wear.

UV-Based Advanced Oxidation Processes of Remazol Brilliant Blue R Dye Catalyzed by Carbon Dots.

UV-based advanced oxidation processes (AOPs) (UV/H2O2 and UV/S2O82−) with a titanium(IV)-doped carbon dot, TiP-CD, as a catalyst were developed for the decomposition of Remazol Brilliant Blue R (Reactive Blue 19), an anthraquinone textile dye (at T = 25 °C and pH = 7). The Ti-CD, with marked catalytic UV properties, was successfully synthesized by the one-pot hydrothermal procedure, using L-cysteine as carbon precursor, ethylenediamine as nitrogen source, PEG (polyethylene glycol) as a capping agent, and titanium(IV) isopropoxide (precursor of TiO2 doping). Contrary to azo dyes (methyl orange, orange II sodium salt, and reactive black 5), which achieved complete degradation in a time interval less than 30 min in the developed AOP systems (UV/H2O2, UV/S2O82−, and UV/TiO2), the RBB-R showed relatively low degradation rates and low discoloration rate constants. In the presence of the catalyzer, the reaction rate significantly increased, and the pseudo-first-order rate constants for the RBB-R discoloration were UV/3.0 mM H2O2/TIP-CD-0.0330 min−1 and UV/1.02 mM S2O82−/TIP-CD-0.0345 min−1.

Decolorization and Degradation of Methyl Orange Azo Dye in Aqueous Solution by the Electro Fenton Process: Application of Optimization

In a batch reactor, the EF advanced oxidation decolorization of aqueous solutions of methyl orange MO, a commercial azo reactive textile dye, was investigated in the presence of two different electrodes. The evaluation included various operational variables such as the IC current intensity (60 mA, 80 mA, and 100 mA), initial concentration of pollutant MO (20 mg/L, 40 mg/L, and 60 mg/L), initial pH of solution (3, 5, and 7), temperature of solution (20 °C, 30 °C, and 50 °C), and initial concentration of catalyst [Fe2+] (0.1 mM, 0.2 mM, and 0.3 mM) on the discoloration rate. A Box-Behnken Design of Experiment (BBD) was used to optimize the parameters that directly affect the Electro-Fenton (EF) process. Under the optimal experimental conditions such as [Fe2+] = 0.232 mM, pH = 3, IC = 80 mA, [MO] = 60 mg/L, and T = 30 ± 0.1 °C, the maximum discoloration rate achieved was 94.9%. The discoloration of the aqueous MO solution during the treatment time was confirmed by analysis of the UV-visible spectrum. After a review of the literature on organic pollutant degradation, the EF system provided here is shown to be one of the best in terms of discoloration rate when compared to other AOPs.

Assessment of key processes that govern the degradation of mixtures in photo-Fenton systems

This work focuses on the use of the photo-Fenton process for the treatment of dye mixtures with different compositions. The statistical design of experiments for mixtures and the response surface methodology were used to assess the effect of the dye proportions on both the discoloration rates and the mineralization efficiency. The initial concentrations of catalyst and oxidant, as well as the temperature and the initial pH, were kept constant for all tests. The discoloration rates were followed in terms of the UV–vis absorption spectra evolution, whereas the mineralization efficiencies were assessed by analyzing the decrease of total organic carbon and the consumption of H2O2. The treatment times required for a discoloration of 50% were fitted to a quadratic model (R2 = 0.9347). In addition, within the tested experimental domain, mineralization degrees of at least 80% were achieved after 180 min under all conditions. The analysis of the involved processes shows that the shape of the obtained response surface may be explained by taking into account three key factors: (i) the relative contributions of the internal filter effects, (ii) the inactivation of the catalyst due to the formation of relatively inert coordination complexes with some of the target pollutants, and (iii) the in situ formation of intermediate organic species that can reduce Fe(III) and enhance the catalyst activity.

Effect of UV, pH and solvent on the photophysical properties of novel xanthylium fluorophore in solid and liquid state

The current work describes the comparative study of the photophysical properties of new series of xanthylium fluorophore in different organic solvents, the effect of pH, and the effects of UV light irradiation and stability. The designed molecule plays a significant role in the stability. We disclosed the synthesized molecule's stability from UV–Vis, fluorescence, theoretical studies, the molecule sensitivity to solvent polarity, and pH due to its structural nature. The decrease in absorbance and fluorescence intensity with UV–visible light irradiation for the solid and liquid samples were studied. The dye discoloration rate was estimated. The mechanism for the same has been explored, and the information is given in detail. The electrostatic potential, surface mapping analysis, and the stability of the synthesized dye molecules were studied theoretically and compared with the experimental outcome. The stability study and other factors allowed us to predict the suitable application of the synthesized xanthylium fluorophore.

Use of a residue containing chromium(VI) for dye decomposition using an advanced oxidative process

In this study, a Cr2O3 catalyst was produced from a sulfochromic residue (SCR) generated in the analysis of soil organic matter. The Cr2O3 obtained from the residue was then characterized by techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray fluorescence (XRF), X-ray diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (DRS), and scanning electron microscopy (SEM). To evaluate the applicability of Cr2O3 as a catalyst, methylene blue (MB) dye was evaluated as a model molecule in discoloration and degradation tests. The catalytic tests were performed in the absence (Cr2O3/H2O2) and in the presence of UV radiation (Cr2O3/H2O2/UV) at room temperature (25 ± 1 °C) under constant agitation at 200 rpm. The H2O2 dose, catalyst mass, initial concentration, and pH of the MB solution were optimized for each treatment. The optimized conditions were applied in dye degradation/discoloration. The results showed that Cr2O3 has high catalytic activity, with discoloration and degradation rates of 97% and 60%, respectively, at an equilibrium time of 6 h for both treatments. The catalyst reuse performance was evaluated, and discoloration greater than 80% was observed for MB concentrations of 50 and 100 mg L-1 after 7 cycles. These results showed that SCR treatment minimized the environmental impact by ensuring adequate properties for disposal in accordance with the current Brazilian legislation, in addition to recovering Cr2O3, which was demonstrated to be an efficient catalyst in the degradation of organic compounds via advanced oxidative processes (AOPs).

Effect of natural and commercially produced juices on colour stability of microhybrid and nanohybrid composites

ObjectiveThis study aims to evaluate the discoloration rate of two types of composites, microhybrid and nanohybrid, after exposure to natural and commercially-produced juices.Materials and methodsIn this experimental study, 90 disc-shaped specimens with a thickness of 2 mm and a diameter of 10 mm were taken from two composites, microhybrid P4 (Kerr-ITALY) and nanohybrid Filtek Z250XT (3M-ESPE-USA) (two groups of 45). Then, the samples of each group were divided into five subgroups of nine and were immersed for 10 days for 4 h in five solutions of commercially-produced orange juice, natural orange juice, commercially-produced pomegranate juice, natural pomegranate juice, and distilled water (control group). The colour of the samples was measured by a reflective spectrophotometer using the CLEl*a*b colour space at baseline and after discoloration.ResultThe independent t-test showed that the mean discoloration rate (∆E) of nanohybrid composite exposed to commercially-produced orange juice, natural pomegranate juice, and commercially-produced pomegranate juice was significantly higher than microhybrid composite (P < 0.01). In addition, the test found that the highest discoloration rate of the nanohybrid composite was related to the effect of commercially-produced orange juice (∆E = 13.03) and the highest discoloration rate of microhybrid composite was related to the effect of natural pomegranate juice (∆E = 4.79).ConclusionAccording to the results, it seems that microhybrid composites are more resistant to discoloration than nanohybrid composites. According to the results, consumption of dyed drinks, particularly natural pomegranate juice, commercially-produced orange juice, and commercially-produced pomegranate juice, is not recommended in the first few days after composite restoration.

Copper(II)-Doped Carbon Dots as Catalyst for Ozone Degradation of Textile Dyes.

A catalytic ozonation advanced oxidation process (AOP) with a copper(II)-doped carbon dot as catalyst, Cu-CD (using L-cysteine and polyethylene glycol (PEG) as precursors and passivation agents), was developed for textile wastewater treatment (T = 25 °C and pH = 7). Four dyes were analyzed—Methyl Orange (MO), Orange II sodium salt (O-II), Reactive Black 5 (RB-5) and Remazol Brilliant Blue R (RBB-R), as well as a real effluent from the dying and printing industry. The Cu-CD, with marked catalytic ozonation properties, was successfully synthesized by one-pot hydrothermal procedure with a size of 4.0 nm, a charge of −3.7 mV and a fluorescent quantum yield of 31%. The discoloration of the aqueous dye solutions followed an apparent first-order kinetics with the following rate constants (kap in min−1): MO, 0.210; O-II, 0.133; RB-5, 0.177; RBB-R, 0.086. In the presence of Cu-CD, the following apparent first-order rate constants were obtained (kapc in min−1) with the corresponding increase in the rate constant without catalyst (%Inc): MO, 1.184 (464%); O-II, 1.002 (653%); RB-5, 0.709 (301%); RBB-R, 0.230 (167%). The presence of sodium chloride (at a concentration of 50 g/L) resulted in a marked increase of the discoloration rate of the dye solution due to generation of other radicals, such as chlorine and chlorine oxide, resulting from the reaction of ozone and chloride. Taking into consideration that the real textile effluent under research has a high carbonate concentration (>356 mg/L), which inhibits ozone decomposition, the discoloration first-order rate constants without and with Cu-CD (kap = 0.0097 min−1 and kapc = 0.012 min−1 (%Inc = 24%), respectively) were relatively small. Apparently, the Cu-CD, the surface of which is covered by a soft and highly hydrated caramelized PEG coating, accelerates the ozone decomposition and dye adsorption, increasing its degradation.

Which is the most effective biomaterial in indirect pulp capping? 4- year comparative randomized clinical trial.

The aim of this study is to compare the clinical outcomes of Mineral Trioxide Aggregate (MTA) and calcium hydroxide pulp capping after complete caries removal. In 73 regular patients (47 women, 26 men; age 20.65±3.02 years), having at least one deep carious lesion was recruited. Following complete caries removal, the pulp was indirectly capped with either MTA(n=51) or calcium hydroxide (n =49), randomly. Final restoration with a resin-based composite in a single session was performed. Clinical parameters including pulp vitality, sensitivity to cold or heat stimulants, percussion tests and discomfort during chewing and color were recorded after 6 months, 1 year, 2- year, 3- year and 4- year. Data were analysed statistically (p<0.05). After 4- year, the survival rates were 86% (for MTA), and 82.9% (for calcium hydroxide). Totally, 8 teeth from calcium hydroxide group and 7 teeth from MTA group were endodontically treated. No significant difference was detected between the groups in terms of pulp vitality (p=0.613). Grey discoloration rate was 63% in MTA group. Both pulp-capping materials, MTA and calcium hydroxide showed similar clinically successful performance in terms of pulp vitality in the treatment of deep dentin caries lesions after 4- year.

Efficiency of the heterogeneous catalyst from electrocoagulation sludge for the removal of methylene blue in the presence of persulfate

Persulfate activation by heterogeneous catalysts based on transition metals is of interest in textile effluent treatment processes. Thus, iron-rich electrocoagulation sludge has been thermally treated to obtain new catalysts. The characterization of this catalyst by X-ray diffraction revealed the presence of FeAl2O4 nanoparticles active in the decomposition of persulfate into sulfate radicals (SO4 •−). The efficiency of catalyst/persulfate was monitored during the methylene blue (MB) solution discoloration. The effects of temperature, pH, initial MB concentration, catalyst dose and persulfate dose were also studied. MB removal catalytic activity showed around 94% discoloration and 45.7% TOC reduction after 180 minutes batch reaction at pH = 4.0 (catalyst dose: 0.5 g/L, persulfate dose: 1 g/L; initial MB concentration: 20 mg/L). This catalyst reuse further confirmed its catalytic potential as a discoloration rate of about 82.45% was obtained after five cycles. The biodegradability monitoring measured by the carbon oxidation state (COS) has revealed a remarkable and continuous degradation of organic compounds. The EPR tests revealed that this catalytic reaction generates the radical species responsible for the degradation of MB. Finally, these results show that this catalyst from the thermal activation of electrocoagulation sludge is capable of decomposing persulfate to degrade bioresistant compounds such as textile dyes.

Modified Approach Using Mentha arvensis in the Synthesis of ZnO Nanoparticles—Textural, Structural, and Photocatalytic Properties

Zinc oxide arouses considerable interest since it has many applications—in microelectronics, environmental decontaminations, biomedicine, photocatalysis, corrosion, etc. The present investigation describes the green synthesis of nanosized ZnO particles using a low-cost, ecologically friendly approach compared to the classical methods, which are aimed at limiting their harmful effects on the environment. In this study, ZnO nanoparticles were prepared using an extract of Mentha arvensis (MA) leaves as a stabilizing/reducing agent, followed by hydrothermal treatment at 180 °C. The resulting powder samples were characterized by X-ray diffraction (XRD) phase analysis, infrared spectroscopy (IRS), scanning electron microscopy (SEM), and electron paramagnetic resonance (EPR). The specific surface area and pore size distribution were measured by the Brunauer–Emmett–Taylor (BET) method. Electronic paramagnetic resonance spectra were recorded at room temperature and at 123 K by a JEOL JES-FA 100 EPR spectrometer. The intensity of the bands within the range of 400–1700 cm−1 for biosynthesized ZnO (BS-Zn) powders decreased with the increase in the Mentha arvensis extract concentration. Upon increasing the plant extract concentration, the relative proportion of mesopores in the BS-Zn samples also increased. It was established that the photocatalytic performance of the biosynthesized powders was dependent on the MA concentration in the precursor solution. According to EPR and PL analyses, it was proved that there was a presence of singly ionized oxygen vacancies (V0+) and zinc interstitials (Zni). The use of the plant extract led to changes in the morphology, phase composition, and structure of the ZnO particles, which were responsible for the increased photocatalytic rate of discoloration of Malachite Green dye.

Natural Charcoal in Water Treatment Through Metal Bed Filters Fe°/S/Pz/C: The Concept of Wood-Energy-Sanitation

The concept of the W.E.S (Wood-Energy-Sanitation) for raising awareness among populations far from the distribution networks of drinking water is established. The process of decontaminating filter columns made up of natural charcoal (NC) as porous non-expansive absorbent/adsorbent materials such as pozzolan (Pz) is experienced. The contribution of the NC to the filtering power of the Fe°-based filters, whose decontamination involves the electrochemical oxidation processes of Fe°, and corrosion products (CPs) that can cause a blockage of the reactive surface is studied. To do this, seven systems were tested with reactive zones (RZ) respectively consisting of (1) C (pure NC), (2) Pz (pure Pozzolan), (3) Fe°/C (iron/NC), (4) Fe°/Pz (iron/Pozzolan), (5) Fe°/S/C (Iron/Sand/NC), (6) Fe°/S/Pz (Iron/Sand/Pozzolan), (7) Fe°/S/Pz/C (Iron/Sand/Pozzolan/NC). OM (orange methyl) of 2 mg/L concentration was used as operative indicator. The experiments lasted 40 days per device. Performance parameters such as pH, residual iron, OM discoloration and flow rate were measured. As a result, it appears that the NC alone or associated in the Fe°/C, Fe°/S/C devices has a better filtering power than the Pz. The combination of NC and Pz in the same Fe°/S/Pz/C device improves strikingly the results, such as Fe°/S/Pz/C > Fe°/S/C > Fe°/S/Pz > Fe°/C > Fe°/Pz > C > Pz. Combining two non-expansive porous materials in the RZ stabilizes the Fe°/S/Pz/C-filter and improves its lifespan.

Trametes lactinea and T. villosa collected in Brazil are able to discolor indigo carmine

Dyes used in the textile industry contribute significantly to the increase of water pollution as they are disposed of, most of the time, without proper treatment. Indigo carmine is a synthetic dye widely used in the coloring of jeans and is considered difficult to remove, causing irreversible damage to the food chain in ecosystems. Mycomediation appears as an economical and sustainable way to treat textile effluents, and this work tested three strains of Trametes collected in Brazil against the ability to discolor the indigo carmine and also the activity of laccase, lignin and manganese peroxidases. The experiment was carried out in Kirk medium under static, non-sterile condition, at ± 28 °C for 120 h. Trametes lactinea (URM8350) discolored 81.40 % of the indigo carmine, T. lactinea (URM8350) 85.09 % and T. villosa (URM8022) 96.11 %. Laccase was detected in all specimens. Manganese peroxidase was detected in T. villosa and T. lactinea (URM8354), while lignin peroxidase was not detected in any of the isolates. The ability of T. lactinea to discolor dyes is reported for the first time. The discoloration rates demonstrate the ability of the strains to discolor carmine indigo and their promising use in the discoloration processes in wastewater from the textile segment.

DEGRADATION OF METHYL BLUE BY FENTON PROCESS

In this study, the oxidative degradation of Methyl Blue (MB) triphenylmethane dye, in aqueous solution by Fenton oxidation process was investigated. The UV-Vis spectral changes of Methyl Blue dye during discoloration process were studied. Kinetic study was done to find out the effect of pH on discoloration rate of dye solution.

DEGRADATION OF METHYL BLUE BY FENTON PROCESS

In this study, the oxidative degradation of Methyl Blue (MB) triphenylmethane dye, in aqueous solution by Fenton oxidation process was investigated. The UV-Vis spectral changes of Methyl Blue dye during discoloration process were studied. Kinetic study was done to find out the effect of pH on discoloration rate of dye solution.