Methylene Blue Dye Concentration Research Articles

Adsorptive Removal of Methylene Blue from Aqueous Solution by Spent Mushroom Substrate: Equilibrium, Kinetics, and Thermodynamics

Spent mushroom substrate (SMS), a renewable bio-waste from the mushroom-growing industry, was used as an adsorbent to remove methylene blue (MB) from aqueous solution. SMS was characterized using scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). Adsorption experiments with the SMS adsorbent were performed based on various parameters, such as adsorbent dose, initial MB dye concentration, initial pH, contact time, and temperature. The Langmuir, Freundlich, and Temkin isotherm models were employed to interpret the adsorption behavior. The results indicated that the equilibrium data were perfectly represented by the Temkin isotherm. The maximum adsorption capacity of SMS reached 63.5 mg g-1 at 303 K. The kinetics studies indicated that the pseudo-second-order model best described the adsorption of MB on SMS. The activation energy of the adsorption was 5.64 kJ mol-1. Thermodynamic parameters suggested that the adsorption was an exothermic and spontaneous physical process. The results imply that SMS is a potentially low-cost adsorbent for treating wastewater containing cationic dyes.

Optimization of the column studies into the adsorption of basic dye using tartaric acid-treated bagasse

Previous batch studies have shown that acid treated bagasse is a potentially useful adsorbent for treating dye wastewaters. The present paper examines the use of tartaric acid-modified bagasse for the continuous adsorption of methylene blue (MB) dye in columns. The adsorbent was characterized using Fourier transform infrared spectroscopy and scanning electron microscopy. A 23 full factorial design analysis was carried out to screen the significant parameters that affecting the adsorption of MB dye onto tartaric acid-modified bagasse, namely initial MB concentration (100–300 mg/L), column bed height (40–80 mm), and feed flow rate (5–15 mL/min). The adsorption process was optimized using response surface methodology -central composite design with the help of Minitab® 14 software. Maximum decolorization (99.42%) and chemical oxygen demand reduction (88.40%) could be achieved at 200 mg/L inlet MB dye concentration with 78 mm bed height and 3.5 mL/min of feed flow rate. Thomas and Yoon–Nelson models were in good agreement with the experimental results (r2 ##xgt; 0.91).

Effectiveness of Alkali-Acid Treatment in Enhancement the Adsorption Capacity for Rice Straw: The Removal of Methylene Blue Dye

The effectiveness of alkali-acid modification in enhancement the adsorption capacity of rice straw (RS) for removing a basic dye was studied. The obtained adsorbents were characterized by slurry pH, pHPZC, iodine number, methylene blue number, FTIR, and SEM analyses. Adsorption of methylene blue (MB) was described by the Langmuir, Freundlich, Tempkin, and Redlich-Peterson isotherm models. Effects of contact time, initial concentration of MB dye, pH of solution, adsorbent dose, salt concentration of NaCl, and desorbing agents on the removal of MB were reported. Kinetic studies were analyzed using the pseudo-first-order, pseudo-second-order, and the intraparticle diffusion models and were found to follow closely the pseudo-second-order model. Equilibrium data were best represented by the Langmuir and Redlich-Peterson isotherms. The adsorption capacities were varied between 32.6 and 131.5 mg/g for untreated and treated RS samples with NaOH-1M citric acid (ARS-1C), respectively. Adsorption behavior of the ARS-1C sample was experimented in a binary mixture containing methylene blue (basic) and reactive blue 19 (acidic) dyes which showed its ability to remove MB higher than RB19. Overall, the results indicate that the alkali-acid treatment proved to be potential modification for producing effective low-cost adsorbents for the removal of the basic dyes from wastewater.

Dye-Adsorption Capacity of High Surface-Area Hydrogen Titanate Nanosheets Processed via Modified Hydrothermal Method

High surface-area (380 m2 x g(-1)) hydrogen titanate nanosheets (HTNS) processed via the modified hydrothermal method have been utilized for the removal of methylene blue (MB) dye from an aqueous solution via the surface-adsorption process involving the electrostatic attraction mechanism. The HTNS have been characterized using the transmission electron microscope (TEM), selected-area electron diffraction (SAED), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) specific surface-area measurement techniques. The amount of MB dye adsorbed on the surface of HTNS at equilibrium (q(e)) has been examined as a function of contact time, initial dye-concentration, and initial solution-pH. Within the investigated range of initial solution-pH (2.5-11), the MB dye adsorption on the surface of HTNS has been observed to follow the pseudo-second-order kinetics with the dye-adsorption capacity of 119 mg x g(-1) at the initial solution-pH of - 10. The adsorption equilibrium follows the Langmuir isotherm within the initial solution-pH range of 2.5-10. However, in a highly basic solution (initial solution-pH -11), the adsorption equilibrium has been observed to follow the Langmuir, Freundlich, and Dubinin-Kaganer-Radushkevich (DKR) models in the different ranges of initial MB dye concentration. The mere dependence on the DKR model has not been observed within the investigated range of initial solution-pH. The differences in the dye-adsorption characteristics and capacity of HTNS, compared with those of hydrogen titanate nanotubes, have been attributed to the difference in their specific surface-area. Irrespective of the morphology, the maximum coverage of MB dye on the surface of hydrogen titanate has been noted to be the same (52%).

Adsorption of basic dye onto raw and surface‐modified agricultural waste

The application of raw Bangalora (Totapuri) mango seed kernel powder (RMS) and surface‐modified Bangalora (Totapuri) mango seed kernel powder (SMMS) for the removal of methylene blue (MB) dye from aqueous solution was investigated under ambient conditions. The adsorbent was characterized by the FTIR and SEM analyses. Batch adsorption studies were conducted by varying the solution pH, adsorbent dose, initial MB dye concentration, and contact time. The optimum conditions for the adsorption of MB dye onto the adsorbent was found to be: pH (8.0), adsorbent dose (1.0 g: RMS and 0.4 g: SMMS), contact time (60 min: RMS and 30 min: SMMS), temperature of 30°C for an initial MB dye concentration of 100 mg/L. Adsorption isotherm data were analyzed by the Langmuir, Freundlich, Temkin, and Dubinin‐Radushkevich isotherm models. Experimental data was successfully applied to the Freundlich model than the Langmuir model, and the maximum monolayer adsorption capacity was found to be greater for SMMS than the RMS. Adsorption kinetics was tested with the pseudo‐first‐order and pseudo‐second‐order kinetic models. The kinetic results show that the adsorption process followed the pseudo‐second‐order kinetic model. Adsorption kinetic data were further applied to the intraparticle diffusion, Boyd kinetic and shrinking core models to explain the adsorption mechanism. Adsorption mechanism results shows that the adsorption process was controlled by both internal and external diffusion. The results of this study show that the SMMS could be used as an effective and low‐cost adsorbent for the removal of dyes from aqueous solution. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 87–98, 2014

Synthesis, characterization and photocatalytic activity of PVP stabilized ZnO and modified ZnO nanostructures

In the present study, ZnO nanostructures have been successfully synthesized by hydrothermal, sonochemical and precipitation methods using polyvinyl pyrrolidone (PVP) as the capping agent. The ZnO nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), UV–Visible spectroscopy and photoluminescence (PL) techniques. The XRD results revealed the hexagonal wurtzite structure of the ZnO nanostructures for all the samples. Furthermore, the morphology of the ZnO particles was obtained from FESEM micrographs. Particles prepared by hydrothermal method were found to be rice grain shaped and that prepared by precipitation and sonochemical methods were spherical shaped. Sunlight driven photocatalytic degradation of methylene blue (MB) was studied for ZnO nanostructures synthesized by various methods. The ZnO nanostructures were further decorated with Ag nanoparticles to enhance its dye degradation efficiency. The Ag decorated ZnO nanoparticles exhibited a higher degradation rate as compared to pure ZnO nanoparticles which was independent of pH. Since this process of dye degradation relies on the degradation of dye due to oxidation by highly reactive hydroxyl radicals, there are many factors which affect the efficiency of this process. Hence a study was conducted on the effect of various parameters on ZnO viz amount of catalyst, reaction pH and concentration of MB dye.

Effect of Photodynamic Therapy with Different Formulations of Methylene Blue in Teeth Contaminated by Enterococcus faecalis

The aim of this study was to compare the disinfection of dentine using photodynamic therapy with methylene blue in different formulations. Thirty bovine teeth roots were autoclaved and incubated with a suspension of Enterococcus faecalis. The specimen were randomly divided into three groups: G1, the roots were filled with 10 mM methylene blue dissolved in water; G2, the roots were filled with 10 mM methylene blue dissolved in a mixture of glycerol: ethanol: water; G3, roots filled with 100 mM methylene blue dissolved in water. The groups were irradiated with a 660 nm diode laser with an output power of 100 mW for 4 min, energy density of 850 J/cm2 and after this procedure, the sensitizer was removed and microbial samples were collected from within the root canals. The samples were plated on mEnterococcus to count the colony-forming units (CFU/mL). The means were: Group 1=513×103, Group 2=1431×103 and Group 3=2.96×103. The statistical analysis detected higher disinfection achieved by G3 when compared with groups G1 and G2, and no significant difference between the groups G1 and G2 (P>0.05). The increase of the concentration of methylene blue dye achieved higher disinfection in photodynamic therapy.

Adsorption behavior of methylene blue dye onto surface modified Strychnos potatorum seeds

Kinetic, mechanism, equilibrium, and thermodynamic behavior of adsorption of methylene blue (MB) dye onto surface modified Strychnos potatorum seeds (SMSP), in an aqueous solution were studied. Batch adsorption experiments were carried out to analyze the effect of initial solution pH, adsorbent dose, contact time, initial MB dye concentration, and temperature on the removal of MB dye. The kinetics of MB dye adsorption onto SMSP follows a pseudo‐second order kinetic model. The adsorption of MB dye onto SMSP was found to be controlled by both surface diffusion and pore diffusion. The diffusivity values were calculated from Boyd kinetic and Shrinking Core Model for varying initial MB dye concentration from 50 to 250 mg L−1. The adsorption equilibrium data were fitted to different adsorption isotherm models such as Langmuir, Freundlich, and Dubinin‐Radushkevich. The equilibrium data fitted best with the Freundlich adsorption isotherm model, which indicates multilayer adsorption of MB dye onto SMSP. The maximum monolayer adsorption capacity estimated with Langmuir isotherm model was 78.84 mg of MB dye molecules per gram of SMSP. Thermodynamic studies showed that the adsorption of MB dye onto SMSP follows an exothermic process. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 624–632, 2013

Silica‐Based NTPC‐Fly Ash for Dye‐Removal Application and Effect of Its Modification

Silica‐based fly ash (FA) received from the National Thermal Power Corporation (NTPC), India has been utilized for determining its dye‐adsorption capacity. The dye adsorption using the NTPC‐FA has been examined by varying the initial methylene blue dye concentration (7.5–150 μM) and initial solution‐pH (2.5–11.5). The dye‐adsorption capacity of NTPC‐FA has been found to be 0.43 mg/g. To increase the dye‐adsorption capacity, the NTPC‐FA is subjected to the hydrothermal treatment and typical washing cycles without and with the coating of sol–gel derived anatase‐titania. The hydrothermally treated NTPC‐FA and hydrogen titanate–silica composite thus obtained exhibit dye‐adsorption capacity higher than that of NTPC‐FA.

Studies on the Adsorption of Methylene Blue Dye from Aqueous Solution onto Low-Cost Tartaric Acid Treated Bagasse

The capacity of tartaric acid (TA) treated bagasse for adsorption of methylene blue (MB) dye from aqueous solution was studied in batch experiments. The effect of relevant parameters such as function of pH, adsorbent dosage, contact time, and initial MB dye concentration was evaluated. The adsorbent was characterized using Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). Experimental data were analyzed in terms of pseudo-first order, and pseudo second order. The results showed that the adsorption process of MB dye followed well pseudo-second order kinetics. The adsorption data of MB dye at 300, 303, 313, 323, 333K are corresponded to Langmuir, and Freundlich isotherms. The adsorption process followed the Langmuir isotherm as well as Freundlich isotherm.

Photocatalytic Degradation of Methylene Blue by Fe/ZnO/SiO2Nanoparticles under Visiblelight

The photocatalytic activity of Fe/ZnO/SiO2catalysts under visible-light irradiation for the degradation of methylene blue was evaluated. The effect of pH, illumination time, amount of catalyst loaded, and initial dye concentration on the degradation efficiency of methylene blue was investigated. The results reveal that the optimum photocatalytic oxidation conditions of methylene blue are as follows:pH=4and illumination time is 30 min, the amount of catalyst loading is 0.075 g/L and 50 ppm methylene blue dye concentration. Under these conditions, the removal efficiency of methylene blue was 100%.

Adsorption of methylene blue dye from aqueous solution by agricultural waste: Equilibrium, thermodynamics, kinetics, mechanism and process design

The adsorption of methylene blue (MB) dye from aqueous solution onto a cashew nut shell (CNS) was investigated as a function of parameters such as solution pH, CNS dose, contact time, initial MB dye concentration and temperature. The CNS was shown to be effective for the quantitative removal of MB dye, and the equilibrium was reached in 60 min. The experimental data were analysed by two-parameter isotherms (Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models) using nonlinear regression analysis. The characteristic parameters for each isotherm and the related correlation coefficients were determined. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° were also evaluated, the sorption process was found to be spontaneous and exothermic. Pseudo-first-order, pseudo-second-order and Elovich kinetic models were used to analyze the adsorption process. The results of the kinetic study suggest that the adsorption of MB dye matches the pseudo-second-order equation, suggesting that the adsorption process is presumably chemisorption. The adsorption process was found to be controlled by both surface and pore diffusion. Analysis of adsorption data using a Boyd kinetic plot confirmed that the external mass transfer is a rate determining step in the sorption process. A single-stage batch adsorber was designed for different CNS doses to effluent volume ratios using the Freundlich equation. The results indicated that the CNS could be used effectively to adsorb MB dye from aqueous solutions.

Optimization of decolorization of methylene blue by lignin peroxidase enzyme produced from sewage sludge with Phanerocheate chrysosporium

Optimization of decolorization of methylene blue (MB) dye by lignin peroxidase (LiP) enzyme produced by white-rot fungus Phanerochaete chrysosporium using sewage treatment plant (STP) sludge as a major substrate was carried out in the laboratory. Optimization by the one-factor-at-a-time (OFAT) and statistical approach was carried out to determine the process conditions on optimum decolorization of MB dye using LiP enzyme in static mode. The OFAT method indicated that the optimum conditions for decolorization of MB dye (removal: 14–40%) was at temperature 55 °C, pH 5.0 with hydrogen peroxide (H 2O 2) concentration 4.0 mM, MB dye concentration 20 mg/L and LiP activity 0.487 U/ml. The addition of veratryl alcohol to the reaction mixtures did not contribute any further increases in decolorization. The initial concentration of MB and the activity of LiP enzyme were further optimized using response surface methodology (RSM). The contour and surface plots suggested that the optimum initial concentration of MB and LiP activity predicted were 15 mg/L and 0.687 U/ml, respectively for the removal of 65%. The validation of the model showed that the decolorization process gave the higher removal of 90% in agitation mode compared to the static mode with 65% for 60 min of incubation time by LiP enzyme.

Bench-scale and packed bed sorption of methylene blue using treated olive pomace and charcoal

A combination of olive pomace after solvent extraction and charcoal produced from the solid waste of olive oil press industry was used as an adsorbent for the removal of methylene blue (MB) dye from aqueous solutions. Batch tests showed that up to 80% of dye was removed when the dye concentration was 10 mg/ml and the sorbent concentration was 45 mg/ml. An increase in the olive pomace concentration resulted in greater dye removal from aqueous solution, and an increase in MB dye concentration at constant adsorbent concentration increased the dye loading per unit weigh of adsorbent. In the kinetic of the adsorbent process, the adsorption data followed the second-order kinetic model better than first order kinetic model. Charcoal showed higher sorption capacity (uptake) than that of olive pomace. In the fixed bed adsorption experiment, the breakthrough curves showed constant pattern behavior, typical of favorable isotherms. The breakthrough time increased with increasing bed height, decreasing flow rate and decreasing influent concentration and methylene blue dye uptake. The uptake of MB dye was significantly increased when a mixture of olive pomace and charcoal was packed in the column in a multi-layer fashion. Different models were used to describe the behavior of this packed-sorption process.

Treatment of waters colored with methylene blue dye by vacuum membrane distillation

Textile industries consume large amounts of water and generate highly dye-contaminated effluents. Textile wastewaters have to be treated in order to be recycled in the process or to meet legislative requirements before being discharged. The objective of the present study was to examine the potential use of the vacuum membrane distillation process for the treatment of dyed solutions. Methylene blue (MB) was used as a model dye. Batch experiments were conducted on dilute MB-water mixtures using a tubular polypropylene membrane module. The concentration of MB dye within the feed reservoir was monitored over time. The impact of operating variables such as feed temperature, flow rate and initial dye concentration was investigated. A mathematical model incorporating temperature and concentration polarization effects was developed and validated on the experimental data.

Effect of solid polymer electrolyte on the sensitization of photocurrents in solid-state electrochemical cells using conducting polypyrrole

The effect of small concentration of methylene blue dye on photocurrents was studied in the solid-state photoelectrochemical cells fabricated using conducting polypyrrole-coated electrodes sandwiched with solid-polymer electrolyte, namely, polyvinylpyrrolidone with phosphoric acid. A maximum photosensitivity factor (S=I l/I d, where I l is the photocurrent and I d is the dark current) of the order of 5 is observed. The current–voltage (I–V) characteristics in such cells reveal that charge transport is mainly governed by the space charge effect. Comparison of the results presented in this paper with the ones we reported earlier [23] indicates that the matrix in which dye has been incorporated plays an important role in such sensitization processes. A matrix that can efficiently transport the photogenerated charge carriers is observed to be more suitable for such dye-sensitized devices.

Demarcation of nonmelanoma skin cancer margins in thick excisions using multispectral polarized light imaging.

More than a million cases of nonmelanoma skin cancers are diagnosed every year. Treatment of cancer patients could benefit greatly if a real-time, noninvasive, reliable, and cost-effective technique for delineating tumor margins were available. A novel multispectral dye-enhanced polarized light imaging technique that enables rapid imaging of large tumor fields is described. A tunable monochromatic light source and a CCD camera were employed as the imaging device. Linear polarizers were introduced into both the incident and collected light pathways in order to limit the measurement volume to the superficial tissue layers. To enhance the tumor contrast in the image, aqueous solutions of toluidine blue or methylene blue were topically applied to fresh thick skin excisions for several minutes. Then the specimens were rinsed in saline solution. Images were acquired before and after staining at the selected wavelengths. The two sets of wavelengths corresponding to the hemoglobin Soret absorption band and to the absorption bands of the dyes were used to demarcate the areas of enhanced hemoglobin and dye absorption, respectively. The resulting images demonstrate that staining significantly enhances contrast of the tumor in the image and enables reliable delineation of cancer. Locations and shapes of tumor lobules revealed by polarized light images closely correspond to those found in Mohs frozen sections for 41 specimens out of 45. The study demonstrates that the suggested technique has significant potential as a guidance tool in tumor excision surgery.

Photodynamic inactivation of pseudorabies virus with methylene blue dye, light, and electricity.

Pseudorabies virus was photoinactivated with a combination of methylene blue dye, light, and electricity. Viral suspensions were mixed with variable amounts of methylene blue dye and then were placed in a current source apparatus. Total inactivation of pseudorabies virus (1.7 X 10(6) 50% tissue culture infective doses per ml) was achieved with constant mixing, a methylene blue dye concentration of 10(-4) M, and an electrical current of 12 microA for 12 min.