Naphthol Blue Black Dye Research Articles

Hydrothermal synthesis of cadmium sulfide decorated reduced graphene oxide photocatalyst for the degradation of photostable naphthol blue black dye

Photocatalysis is being used for the mineralization of recalcitrant organic pollutants in water that cannot be treated with conventional methods. Cadmium sulfide decorated reduced graphene oxide (rGO-CdS) nanocomposite photocatalyst was synthesized by hydrothermal method and evaluated for the removal of a photostable textile azo dye, naphthol blue black (NBB) under ultraviolet light (UV-A, 365 nm). The rGO-CdS combination was opted for due to utilizing the narrow band gap (Eg = ~2.4 eV) of CdS and robust rGO support, capable of attracting organic pollutants to surface, bear, and protect CdS from photocorrosion. The formation of rGO-CdS was proved from the findings of physiochemical characterization UV–visible-, X-ray diffraction photoelectron, Raman, energy dispersive X-ray-spectroscopic, and scanning, transmission electron, and atomic force microscopic studies. The spherical CdS was decorated on the random shaped rGO sheets. Eg of CdS and rGO-CdS were 2.42 and 2.39 eV, respectively. After 2 h of light exposure, 2 g/L of rGO-CdS mineralized 95 % of NBB (2 × 10−4 mol/L). After 5 cycles, 80 % of photocatalytic efficiency was retained. In gas chromatography-mass spectrometry studies, 8 fragments of NBB were found after 1 h and confirmed that the degradation was mediated by photocatalytic dilapidation. The optimum pH for NBB degradation was 9. The rGO-CdS was found to be a potentially stable and reusable photocatalyst for environmental applications.

Synthesis of Ag @CuO nanocomposites supported by reduced graphene oxide nanosheets: harnessing photocatalytic degradation of naphthol blue black dye

The significance of utilizing photocatalysts to degrade toxic dyes and microbes has grown in recent years. It has been demonstrated as a successful method for utilizing light through hybrid photocatalysts to break down harmful organic molecules. This study aims to investigate the potential applications of CuO–Ag/rGO nanocomposites in environmental remediation. The nanocomposites were synthesized by incorporating Ag and CuO nanoparticles onto rGO nanosheets via hydrothermal method. The nanocomposites that resulted were thoroughly characterized using various analytical techniques to determine their chemical structure, morphology, crystallinity, and photocatalytic application. The degradation efficiency of naphthol black blue (NBB) dye under visible light irradiation was used to assess the photocatalytic performance of the nanocomposites. It was revealed that 80.2%, 90.3%, and 97.3% of NBB dye degraded as a result of enhanced photocatalytic activity of synthesized CuO–Ag/rGO. The research provides valuable insights into the design and development of advanced nanomaterials for efficient and sustainable wastewater treatment applications.

Photocatalytic degradation of naphthol blue black dye using undoped and Al-doped cobalt ferrite nanoparticles

The current study aims to evaluate the effectiveness of undoped (CoFe2O4) and aluminium-doped cobalt spinel ferrite (CoFe1.1Al0.9O4) nanoparticles as photocatalysts in the process of photocatalytic degradation of organic naphthol blue black (NBB) dye. In the sol-gel auto combustion method, a combination of metal nitrates, citric acid, sodium hydroxide, and liquid ammonia was utilized as the raw chemical ingredients for synthesizing nanoparticles of CoFe2-xAlxO4 (x = 0.0, 0.3, 0.6, 0.9, 1.2, 1.5) spinel ferrites. The nanoparticles were subjected to various characterization techniques including thermal analysis (TGA/DTA), X-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), and UV–visible spectroscopy for comprehensive analysis. The XRD analysis confirmed the presence of a spinel cubic structure in the synthesized spinel ferrite nanoparticles. The interplanar distance (d) and crystalline size (D) were determined using Bragg's equation and Scherrer's relationship, respectively. The morphological characteristics and elemental composition of the spinel ferrites were confirmed through FE-SEM and EDS. Furthermore, the UV spectrum of the synthesized photocatalyst was investigated to compare the energy band gap between undoped and Al-doped cobalt spinel ferrites. The analysis of photoluminescence (PL) spectra was conducted to investigate the dynamics of charge carriers, focusing on their transfer, relocation, and recombination processes. The surface area of the synthesized photocatalyst ranged from 3.525 to 16.113 m2/g. Photocatalytic degradation of naphthol blue black (NBB) dye was carried out under visible light exposure utilizing both cobalt spinel ferrite nanoparticles without doping and those doped with aluminium. Several factors, including pH level, H2O2 concentration, amount of photocatalyst (spinel ferrite) and initial dye concentration, were considered through the photocatalytic degradation of NBB dye. The highest percentage degradation (%) of NBB dye was determined at pH 11. For NBB dye with an initial concentration of 20 ppm, the maximum degradation was achieved using 200 mg of spinel ferrite nanoparticles per 100 mL dye solution under visible light irradiation for 40 min.

Green Synthesis, Characterization, and Photocatalytic Activity of Zinc Oxide Nanoparticles on Photodegradation of Naphthol Blue Black Dye

Zinc oxide (ZnO) nanoparticles have been successfully synthesized using water extract of red dragon fruit (Hylocereus polyrhizus) stem with zinc acetate dihydrate as a precursor of ZnO. Chemical compounds contained in the red dragon fruit stem extract, such as phenolics, terpenoids, and steroids, acted as reducing agents, stabilizers, and capping agents. The phase structure, crystallite size, functional groups, shape, and morphology of ZnO nanoparticles were determined by X-ray diffraction (XRD), Fourier Transform infrared (FT-IR) Spectroscopy, and Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX). The XRD pattern confirmed the crystallinity of synthesized zinc oxide was in the zincite (ZnO) phase with an average crystallite size of 79.09 nm. Spectroscopy FTIR analysis showed that the synthesized ZnO nanoparticles had characteristics similar to the ZnO standard/commercial. SEM-EDX analysis revealed that the synthesized ZnO nanoparticles were spherical, evenly distributed, and homogeneous particle size. The photocatalytic activity of synthesized ZnO nanoparticles was evaluated on the photodegradation of naphthol blue black (NBB) dye. The results showed that the synthesized ZnO nanoparticles have high photocatalytic activity that can degrade NBB dye up to 98.82%. This high photocatalytic activity was obtained at operating parameter conditions with the initial pH of NBB at 2, the dosage of ZnO nanoparticles at 250 mg, and the initial dye concentration at 10 ppm.

Synthesis of Solar Light Active Reduced Graphene Oxide-ZnS Nanomaterial for Photocatalytic Degradation and Antibacterial Applications.

Good water quality is essential for life; therefore, decolorizing and detoxifying organic dye wastes (textile effluents) have gained immense environmental importance in recent years. Thus, the degradation of wastewater has become a potential need for our environment. This research aims to synthesize and investigate a ceramic-based nanomaterial catalyst for the degradation of dye solution under exposure to sunlight. A reduced graphene oxide-ZnS (rGO-ZnS) nanomaterial was qualitatively synthesized using a solvothermal method. The prepared nanomaterial was characterized using XRD, SEM, HR-TEM, EDX, XPS, and FT-IR techniques. The photocatalytic activity of the rGO-ZnS nanomaterial was checked using oxidative photocatalytic degradation of naphthol blue black dye (NBB) under direct sunlight irradiation. Here, the rGO/ZnS composite showed a significant photocatalytic performance to degraded NBB (93.7%) under direct solar light. Chemical Oxygen Demand (COD) measurements confirmed the mineralization of the dye. The influence of different radical scavengers on NBB degradation was studied. Optimum conditions for efficient degradation were determined. The antibacterial property of the prepared catalyst was studied.

Outstanding performance of electro-Fenton/ultra-violet/ultra-sound assisted-persulfate process for the complete degradation of hazardous pollutants in contaminated water

This work focuses on the degradation of the hazardous azo dye Naphthol Blue Black (NBB) utilizing an innovative approach combining electro-Fenton (EF), ultra-violet (UV), and ultra-sound (US) processes while varying the operating parameters (concentration of iron and dye, pH, current intensity). Under the optimum experimental conditions, an excellent degradation efficiency of the NBB dye is achieved after 60 min, i.e., 98%, 95%, and 65% for EF, UV, and US processes, respectively. The addition of persulfate significantly improves the efficiency and accelerates the kinetics of the NBB degradation. Combining all processes assisted with persulfate achieved 99% NBB degradation within a very short contact time of 2 min and 98% reduction in COD after 55 min. The as-obtained outstanding performance associated with the synergistic effects of EF/US/UV alongside the addition of persulfate can be adopted to degrade other hazardous substances.

Co-Precipitation Synthesis of Clay-Magnetite Nanocomposite for Adsorptive Removal of Synthetic Dye in Wastewater of Benang Bintik Batik

Clay is a natural material that has been widely applied as a low-cost adsorbent for removing various contaminants from wastewater. To improve its characteristics and activity, natural clay from Central Kalimantan was activated by acid and calcination treatments, then synthesized with magnetite (Fe3O4) in nanocomposite by co-precipitation method. The obtained nanocomposite was further characterized by Fourier transform infrared spectroscopy, X-ray diffraction, nitrogen adsorption, vibrating sample magnetometry, and transmission electron microscopy methods. The results showed that co-precipitation method has been successfully produced clay-magnetite nanocomposite from activated clay with specific surface area, saturation magnetization, and particle size were 37.458 m2/g, 24.910 emu/g, and 50 nm, respectively. The obtained natural clay, activated clay, and clay-magnetite nanocomposite were then evaluated for adsorptive removal of naphthol blue black (NBB) synthetic dye from wastewater generated by an industry of Benang Bintik batik in Central Kalimantan using a batch system. The results showed that optimum pH for adsorptive removal process from these adsorbents were 2, while the optimum contact times of natural clay, activated clay, and clay-magnetite nanocomposite were 90, 60, and 60 minutes, respectively. The clay-magnetite nanocomposite also showed a much better removal efficiency (99.58%) than activated clay (86.28%) and natural clay (68.27%). The utilization of clay-magnetite nanocomposite as adsorbent not only can increase its removal efficiency against NBB dye, but also can facilitate the separation of the adsorbent solid phase from wastewater using an external magnetic field after the adsorptive removal process.

Sunlight driven improved photocatalytic activity of Mn doped SnO2 nanowires

Sn1-xMnxO2 (x = 0, 0.1, 0.2 and 0.3) were successfully synthesized by simple Co-precipitation technique. The influence of Mn dopant on the crystal structure, surface morphology, optical, magnetic and electrical properties of SnO2 were investigated by various techniques like XRD, IR, TG/DSC, SEM, TEM, EDX, DRS, photoluminescence, magnetic susceptibility and electrical resistivity. XRD pattern reveal formation of tetragonal structure for undoped and Mn doped SnO2. SEM and TEM images of Mn doped SnO2 revealed formation of nanowires of different diameter and length. Mn substitution in SnO2 crystal lattice leads to widening of band gap and paramagnetic behavior. The photocatalytic activity was evaluated by the degradation of Naphthol Blue Black dye under solar light. Enhanced photocatalytic efficiency is exhibited by Sn0·7Mn0·3O2 within 180 min time. 92% reduction in COD value and presence of inorganic ions indicate complete mineralization of the NBB dye. Antibacterial activity of SnO2 towards gram positive and gram negative bacteria is also enhanced with Mn doping.

Synthesis of Metal Complex for Photocatalytic Degradation of Dyes under Visible Light Irradiation

In the present work, Schiff base ligand has been synthesized from synthesized dialdehyde and primary amine. The synthesized ligand and its copper metal complex were characterized by melting point & spectral analysis such as IR, 1HNMR, 13C and GC-MS. In the presence of H2O2 as an oxidising agent the photocatalytic performance of the complex was assessed by the photodegradation of dyes. By carrying spectrophotometrically on irradiation of visible light using Cu(II) metal complex of Schiff base ligand the photocatalytic degradation of Naphthol Blue Black dye (NBB), Rhodamine B (RB) and Methylene Blue (MB) dyes was carried out. The photocatalytic degradation of NBB, RB and MB dyes was carried out with reference to effect of time. The results revealed that Cu-complex of Schiff base ligand is consistent for photocatalysis of these dyes for treatment of authentic effluents. The results show that the optimal dose for maximal degradation of these dyes was found to be 5 mgL-1 of the Cu(II) metal complex. The % degradation of NBB, RB and MB were found to be 55%, 50% and 80% in the visible light irradiation. The % degradation of MB dye was greater as compare to other two dyes. The order of % degradation of three dyes by copper metal complex was found as MB > NBB >RB

CFD modeling of vacuum membrane distillation for removal of Naphthol blue black dye from aqueous solution using COMSOL multiphysics

A 3D CFD model was developed using COMSOL Multiphysics to predict the permeate flux and interfacial temperatures for Naphthol Blue-Black dye from its aqueous solution using vacuum membrane distillation(VMD) technique. The transport equations for momentum, heat, and mass transfer wereembracedin this CFD model. The heat and mass transfer coupling werealso incorporated at the contacting interfacial boundaries of feed solution with the membrane surface. Temperature and concentration distribution inside the membrane and module were determined using CFD modeling, and the theoretical permeate flux was evaluated using the convective heat transfer mechanism through the porous membrane structure.The effects of different process conditions of various factors like flow, temperature, vacuum, and concentration wereanalyzed on permeate flux through the developed CFD model. By determining the interfacial temperatures using CFD model, the temperature polarization coefficient (TPC)was estimated at different operating parameters. The comparison of developed CFD model is carried out with experimental conditions, and it is found best fitted with experimental data.

Waste Moringa oleifera seed pods as green sorbent for efficient removal of toxic aquatic pollutants

In the present study, biosorption of chromium (Cr(VI)) ions and Naphthol blue black (NBB) dye using Moringa oleifera seed pods powder (MPP) as green biosorbent was investigated. Three different sizes of MPP viz. fine fraction (<53 μm), coarse fraction (>250 μm) and mixed fraction were investigated. The biosorbent was characterized by pHzpc, Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM) in order to get an insight of the surface charge, functional groups, and morphology of the biosorbent, respectively. The biosorption studies were conducted with Cr(VI) and NBB dye and different parameters, such as solution pH, contact time, initial concentration of the pollutant, adsorbent dosage and co-existing ions were examined. Experimental results revealed that the maximum removal of Cr(VI) and NBB dye was observed at pH 1 and 2, respectively and the equilibrium was achieved in ca. 180 min. The removal efficiency of Cr(VI) by fine, mixed and coarse fraction was 91.8, 74.9, 52.6%, respectively, whereas for NBB dye, the removal efficiency for the same fractions was 97.5, 33.6, 18.9%, respectively. The removal efficiency of Cr(VI) and NBB dye was influenced in the presence of competing ions. The biosorption isotherm and kinetic data were best correlated with Langmuir isotherm and pseudo-second order kinetic model, respectively. Column studies were also conducted with MPP by studying different flow rates and adsorbates concentrations to check the practical applicability of MPP in removing target metal and dye pollutants.

Optimization of process variables by the application of response surface methodology for naphthol blue black dye removal in vacuum membrane distillation

This study focuses on the determination of optimum conditions for different operating variables for removal of dye from wastewater in the vacuum membrane distillation process. Response surface methodology was applied to develop a regression model for analysis of permeate flux, specific energy consumption, and percentage removal. A set of experimental runs for VMD setup was developed using the central composite design of experiment method. Three regression correlations models were developed to predict the permeate flux, specific energy consumption and percentage removal using experimental conditions. The developed models were further used to optimize the operating parameters for desired conditions of responses. The optimum conditions for operating parameters were found as 85 °C, 5lpm, 30 ppm and 750 mmHg for feed temperature, feed flow rate, initial dye concentration, and vacuum degree for maximum permeate flux and percentage removal and for minimum specific energy conditions. The developed model was verified with experimental conditions and found as best fitted. The fouling on membrane surface was analyzed using scanning electron microscopy (SEM) and EDS.

Graft Gum Ghatti Caped Cu2O Nanocomposite for Photocatalytic Degradation of Naphthol Blue Black Dye

Photodecolorization of naphthol blue black dye through the use of Cu2O nanoparticles capped with a biopolymer matrix containing gum ghatti (Gg) grafted with acrylic acid (AA) and acrylamide (AAm) (Cu2O/Gg–AAm–AA) has been studied. While the homogeneous co-precipitation method was adopted for the synthesis of the Cu2O nanoparticle, its incorporation into the biopolymer matrix (Gg–AAm–AA) was performed through the graft copolymerization method. The synthesized Cu2O and Cu2O/Gg–AAm–AA were characterized using SEM, TEM, XRD, EDX and UV–Vis spectroscopies, and BET surface area analysis. The photodecolorization experiment was performed using simulated ultraviolet and visible light irradiations, and these results compared with that of adsorption studies. The influence of pH, catalyst dose and dye concentration on the decolorization efficiency were also taken into consideration. The results revealed the Cu2O/Gg–AAm–AA to be an excellent photocatalyst for effective elimination of naphthol blue black dye from water. The process was observed to be pH dependent, with pH 6 being the optimum value. The photodecolorization process increased with increasing catalyst concentration but decreased beyond the optimum value of 0.3 g L−1. The process also decreased with increasing dye concentration. The result of the recyclability study indicates that the Cu2O/Gg–AAm–AA nanocomposite can be effectively recycled and re-used over a number cycles.

Enhanced photo-catalytic degradation of naphthol blue black on nano-structure MnCo2O4: charge separation of the photo-generated electron–hole pair

MnCo2O4 nano-composite photocatalyst was synthesized via co-precipitation technique. Composite formation of cobalt oxide with manganese was intended to create tail states within the band gap of cobalt oxide for better charge separation of the photo-generated electron–hole pairs in nano-composite photocatalyst. The MnCo2O4 nano-composite can effectively mineralize organic contaminants. MnCo2O4 nano-composite photocatalyst was characterized by X-ray diffraction, field emission scanning electron microscopy (FESEM), transmission electron microscopy, energy dispersive X-ray spectroscopy, fourier transform infrared spectroscopy (FTIR) and UV–Vis diffuse reflectance spectra (UV–Vis DRS). X-ray diffraction analysis showed cubic manganese cobalt oxide MnCo2O4. FESEM results showed spherical nanoparticles with cauliflower nanostructure. The mean size of particles was in the ranges of 30–60 nm. The band gap for MnCo2O4 nano-composite photocatalyst was 1.95 and 2.49 eV, based on the results of diffuse reflectance spectra. FTIR results showed two type of fundamental absorption bands at 620 and 505 cm−1 due to stretching vibrations of Mn–O and Co–O, respectively. The photo-catalytic activitie of nano-composite photocatalysts were investigated using a naphthol blue black dye as textile dye contaminant and the results showed an outstanding performance yielded 92 % total organic carbon removals attributed to charge separation of the photo-generated electron–hole pairs in nano-composite.

Sonophotocatalytic treatment of Naphthol Blue Black dye and real textile wastewater using synthesized Fe doped TiO2

This study examines the treatment of Naphthol-Blue–Black (NBB) dye and real textile wastewater through sonophotocatalytic technique. Fe, TiO2 and Fe-TiO2 were synthesized and characterized by SEM, XRD and DRS which revealed its high purity, good doping, nanosize and higher light absorption capacity. The effect of pH, gas content (Ar, O2, air and N2), H2O2 concentration and catalyst loading were examined. The maximum color removal was observed for initial pH 11, argon gas bubble, 44.1mmol/L H2O2, 3g/L Fe, 4g/L TiO2 and 2.2g/L Fe-TiO2. However, 96% was achieved by sonophotocatalytic process for 2.2g/L 1:7 Fe:TiO2. Similar methodology for real textile wastewater with Fe-TiO2 (1:7) could remove 91% of TOC.

Quantitation of polyhexamethylene biguanide by photometric titration with Naphthol Blue Black dye

A convenient and reliable method for quantitative determination of polyhexamethylene biguanide in aqueous solutions has been developed, based on complexation of the polymer with Naphthol Blue Black dye. Spectrophotometric titration measuring absorbance at 600 nm leads to characteristic zigzag curves, with the inflexion point at dye to polymer mers molar ratio 1:2. The photometric titration endpoints are characterized with good repeatability, resulting in low variance values. As a result, the limit of polyhexamethylene biguanide determination has been found to be equal to 50 and 150 µmol/dm3 of mers for direct and reverse titration, respectively.

Highly active WO3–Ag–ZnO photocatalyst driven by day light illumination

The WO3 loaded Ag–ZnO (WO3–Ag–ZnO) was successfully synthesized by precipitation–decomposition method. The catalyst was characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) images, energy dispersive spectrum (EDS), transmission electron microscope (TEM), diffuse reflectance spectra (DRS), photoluminescence spectra (PL), cyclic voltammetry (CV) and BET surface area measurements. The photocatalytic activity of WO3–Ag–ZnO was investigated for the degradation of Naphthol Blue Black (NBB) in aqueous solution using solar light. WO3–Ag–ZnO is found to be more efficient than Ag–ZnO, WO3–ZnO, Ag–WO3, WO3, commercial ZnO, bare ZnO, TiO2–P25 and TiO2 (Merck) at pH 9 for the mineralization of NBB dye. The effects of operational parameters such as the amount of photocatalyst, dye concentration, initial pH on photo mineralization of NBB dye have been analyzed. The mineralization of NBB has been confirmed by Chemical Oxygen Demand (COD) measurements. A degradation mechanism is proposed for the degradation of NBB under solar light. This catalyst is found to be reusable.

Solar-light-assisted photocatalytic degradation of NBB dye on Zr-codoped Ag–ZnO catalyst

Zr-codoped Ag–ZnO (Zr–Ag–ZnO) was successfully synthesized by the precipitation–decomposition method. The catalyst was characterized by X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive spectra (EDS), diffuse reflectance spectra, photoluminescence spectra, cyclic voltammetry, and Brunauer–Emmett–Teller (BET) surface area measurements. The photocatalytic activity of Zr–Ag–ZnO was investigated for the degradation of Naphthol Blue Black (NBB) in aqueous solution using solar light. Codoping shifted the absorbance of ZnO to the entire visible region. Zr–Ag–ZnO is found to be more efficient than Ag–ZnO, Zr–ZnO, commercial ZnO, prepared ZnO, TiO2-P25, and TiO2 (Merck) at pH 9 for mineralization of NBB under solar light. The influence of operational parameters such as the amount of photocatalyst, dye concentration, and initial pH on photomineralization of NBB has been analyzed. Mineralization of NBB was confirmed by chemical oxygen demand (COD) measurements. A mechanism is proposed for the degradation of NBB under solar light. The catalyst is found to be reusable.

Solar assisted photocatalytic degradation of Naphthol Blue Black dye using Ce 1− xMn xO 2

The photocatalytic degradation of textile diazo dye Naphthol Blue Black has been investigated using sunlight and Ce 1− x Mn x O 2 ( x = 0, 0.1, 0.2, 0.3 and 1.0) samples. Ce 1− x Mn x O 2 samples were synthesized by co-precipitation method and characterized by XRD, FTIR, thermal techniques and surface areas. Some solid-state studies, such as magnetic susceptibility, electrical resistivity and diffuse reflectance studies were undertaken. The extent of decolourization of the dye was determined by UV–vis spectroscopy. CeO 2 forms solid solution with Mn upto 30 mol% maintaining fluorite structure.

Photoelectrochemical mineralization of textile diazo dye pollutants using nanocrystalline WO 3 electrodes

Photoelectrochemical degradation processes of Naphthol Blue Black (NBB) dye in aqueous solutions were investigated seeking an effective method of degrading textile diazo dyes. Nanocrystalline WO 3 film on a Pt mesh electrode was used as the photoanode for photoelectrochemical degradation of NBB dye. Higher rates of NBB degradation were observed in chloride-containing environments than in sulfate solutions. A strong pH dependence of the NBB dye degradation rate has been found in chloride media. The pH dependence follows the trend of decreasing oxidizing power of electron holes, h VB,s, trapped at the surface of WO 3 particles, with increasing solution pH. In the low pH range (1.0–4.5), photooxidation of the medium favors the formation of Cl and Cl 2 − radicals which are powerful oxidants for the NBB dye. In alkaline solutions, the formation of OH radicals is predominant over Cl and Cl 2 − radicals but the kinetics of NBB degradation is much slower than in acidic media. In sulfate solutions, the rate of NBB photodegradation is slower than in chloride media. Evidently, the lower oxidizing power of the dipersulfate ion S 2O 8 −2 being the oxidant in this environment, is the limiting factor. The intermediates of the NBB dye degradation were detected using HPLC analysis. Possible dye degradation mechanism is proposed.