Dye Solution Temperature Research Articles

Removal of direct blue-106 dye from aqueous solution using new activated carbons developed from pomegranate peel: Adsorption equilibrium and kinetics

The use of cheap, high efficiency and ecofriendly adsorbent has been studied as an alternative source of activated carbon for the removal of dyes from wastewater. This study investigates the use of activated carbons prepared from pomegranate peel for the removal of direct blue dye from aqueous solution. A series of experiments were conducted in a batch system to assess the effect of the system variables, i.e. initial pH, temperature, initial dye concentration adsorbent dosage and contact time. The results showed that the adsorption of direct blue dye was maximal at pH 2, as the amount of adsorbent increased, the percentage of dye removal increased accordingly but it decreased with the increase in initial dye concentration and solution temperature. The adsorption kinetics was found to follow pseudo-second-order rate kinetic model, with a good correlation ( R 2 > 0.99) and intra-particle diffusion as one of the rate determining steps. Langmuir, Freundlich, Temkin, Dubinin–RadushKevich (D–R) and Harkins–Jura isotherms were used to analyze the equilibrium data at different temperatures. In addition, various thermodynamic parameters, such as standard Gibbs free energy (Δ G°), standard enthalpy (Δ H°), standard entropy (Δ S°), and the activation energy ( E a) have been calculated. The adsorption process of direct blue dye onto different activated carbons prepared from pomegranate peel was found to be spontaneous and exothermic process. The findings of this investigation suggest that the physical sorption plays a role in controlling the sorption rate.

Effects of process variables on kinetics of methylene blue sorption onto untreated guava (Psidium guajava) leaf powder: Statistical analysis

The sorption of methylene blue onto untreated guava leaf powder has been studied. The kinetics of sorption of methylene blue is described by pseudo-second-order model. Effects of initial dye concentration, solution temperature, and adsorbent dosage have been studied. The pseudo-second-order rate constant has been correlated as a function of the system variables. Statistical tools like Student's t-test, F-test, ANOVA and lack of fit have been employed to determine the significance of each coefficient that appeared in the model. Model adequacy has been checked by residual distribution. The proposed model explains 95.1% of the total variation in the response.

Adsorption of basic dye on high-surface-area activated carbon prepared from coconut husk: Equilibrium, kinetic and thermodynamic studies

Adsorption isotherm and kinetics of methylene blue on activated carbon prepared from coconut husk were determined from batch tests. The effects of contact time (1–30 h), initial dye concentration (50–500 mg/l) and solution temperature (30–50 °C) were investigated. Equilibrium data were fitted to Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models. The equilibrium data were best represented by Langmuir isotherm model, showing maximum monolayer adsorption capacity of 434.78 mg/g. The kinetic data were fitted to pseudo-first-order, pseudo-second-order and intraparticle diffusion models, and was found to follow closely the pseudo-second-order kinetic model. Thermodynamic parameters such as standard enthalpy (Δ H°), standard entropy (Δ S°) and standard free energy (Δ G°) were evaluated. The adsorption interaction was found to be exothermic in nature. Coconut husk-based activated carbon was shown to be a promising adsorbent for removal of methylene blue from aqueous solutions.

Adsorption properties of congo red from aqueous solution onto N, O-carboxymethyl-chitosan

N, O-carboxymethyl-chitosans ( N, O-CMC) with different degree of substitution (DS) were synthesized under heterogeneous conditions by controlling the reaction temperature. The factors influencing adsorption capacity of N, O-CMC such as the DS of N, O-CMC, initial pH value of the dye solution and adsorption temperature for anionic dye congo red (CR) were investigated. Compared with chitosan (78.90 mg/g), N, O-CMC with the DS of 0.35 exhibited much higher adsorption capacity (330.62 mg/g) for CR at the same adsorption conditions. The adsorption kinetics and isotherms showed that the sorption processes were better fitted by pseudo-second-order equation and the Langmuir equation, respectively. The adsorption mechanism of N, O-CMC was also discussed by means of IR and XPS spectra. The results in this study indicated that N, O-CMC was an attractive candidate for removing CR from the dye wastewater.

Batch kinetic study of sorption of methylene blue by perlite

Batch sorption kinetics of methylene blue by perlite have been studied in terms of pseudo-first-order, pseudo-second-order and intra-particle diffusion models. The results showed that sorption process was best described by the pseudo-second-order model. The correlation coefficients, r 2, obtained from pseudo-second-order model were higher than 0.98 under all the experiment conditions. The effects of agitation speed, initial dye concentration and solution temperature on kinetic parameters (sorption rate constant, initial sorption rate, equilibrium sorption capacity, etc.) are discussed. While the values of sorption rate constants ( k 2) and initial sorption rates ( h) increased with increasing agitation speeds and solution temperatures, it was seen that the values of k 2 decreased and the values of h increased with increased initial dye concentration. The values of equilibrium sorption capacity from pseudo-second order ( q 2) were in the best agreement with experimental data ( q e) in each experimental condition. Moreover, the activation energy ( E a) of sorption calculated using the pseudo-second-order rate constants was found to be 10.31 kJ/mol from an Arrhenius plot. The value of E a indicated that sorption was controlled by an intra-particle diffusion mechanism as well as by pseudo-second-order kinetics.

Design of a transversely pumped, high repetition rate, narrow bandwidth dye laser with high wavelength stability

The paper presents the design and performance of a transversely pumped, narrow bandwidth, high wavelength stability tunable dye laser that neither uses low expansion coefficient materials for construction nor incorporates any active control on the wavelength or the dye solution and environmental temperature as generally used in such lasers. The scheme essentially involves designing the mechanical assembly in such a way that, when bolted together it forms a massive monoblock, enclosing all the optical components and the dye laser axis within itself. This ensures the environmental temperature changes can only affect the output characteristics over long time scale. Short term (pulse to pulse) fluctuations in wavelengths and bandwidths, generally associated with the dye flow instabilities, were minimized by using a specially designed a dye cell made of a near 360°-curved rectangular duct, in which the turbulent flow is transformed itself into laminar flow as it reaches the dye laser axis. The laser was operated with Rhodamine 6G-ethanol-ethylene glycol solution, pumped by a copper vapor laser operating at 5.6 kHz. The dye laser output, consisting of three axial modes, separated by about 990 MHz, was stable over the observation period of about 90 min. Maximum long term (>1 h) fluctuation in Δν/ν was about ±3.6×10−6. The bandwidth of the individual mode varied between 245 MHz to 315 MHz.

Reuse of Activated Sludge Biomass: Equilibrium Studies for the Absorption of Basic Dyes on Biomass

The absorption equilibriums of Basic Yellow 24 and Basic Blue 54 dye by an activated sludge biomass (empirical formula, C60H110O27N8S) are studied. The optimum equilibra tion parameters investigated are 12 hours' equilibration time, 0.8 g L-1 biomass dose, 150-300 μm biomass particle size, 300 ppm initial dye concentration, and 30°C dye solution temperature. The experimental results indicate that for two basic dyes with the same chemical class (thiazole azo) and nearly the same molecular weight, the optimum absorption equilibria are the same but the maximum absorption capacities are different. These absorptive differences could exist because the more hydrophobic residues a dye molecule contains, the more basic dyes the biomass absorbs. The results of analyzing equilibration data show that for the absorption equilibria of two basic dyes absorbed by biomass, the Langmuir absorption isotherm is a better fit than the Freundlich isotherm. The absorption process is exothermic in nature and the absorption type is chemisorption.

Reuse of activated sludge biomass: II. The rate processes for the adsorption of basic dyes on biomass

The rate processes for the adsorption of Basic Yellow 24 dye on activated sludge biomass have been studied. Influences of various factors on adsorption rate, such as shaking rate, initial dye concentration, biomass particle size, and dye solution temperature have been investigated. The experimental results indicate that there is a boundary layer surrounding the biomass particles, the kinetics of the adsorption process is mainly controlled by intraparticle diffusion. The activation energy for the same process was 1.45 kcal mol −1.

Adsorption of Methylene Blue from Aqueous Solution onto Perlite

Adsorption of methylene blue from aqueous solutionsonto unexpanded and expanded perlite samples activatedby H2SO4 and NaCl solutions has beeninvestigated, to assess the possibility of usingperlite for removing cationic dyes from aqueoussolutions. The effects of pH and temperature of dyesolution on the adsorption capacities have beenevaluated. The experimental data were correlatedreasonably well by the Langmuir adsorption isothermand the isotherm parameters (Qm and K) have beencalculated. The removal efficiency (P) anddimensionless separation factor (R) have shown thatperlite can be used for removal of methylene blue fromaqueous solutions, but unexpanded perlite is more effective.

B203レーザ発色法における発色時間に及ぼすフォトクロミック染料濃度と溶液温度の影響

Lifetime of the excited state of the photochromic dye is studied experimentally. From a series of experiments using the solutions composed of combinations of two dyes 1, 3, 3-Trimethylindrino-6'-nitrobenzopyrylospiran and 1', 3'-Dihydro-1', 3', 3'-trimethy1-6- nitrospiro [2H-1-benzopyran-2, 2'- (2H) -indole] and three solvents acetone, toluene and paraffin, the effects of dye concentration and solution temperature on the lifetime are clarified. Further, the present photochromic technique is shown to be applicable to flow visualization of natural convection of organic solvents with relatively high temperature and low velocity.

Utilization of by‐pass kiln dust for colour removal of wastewater streams

The removal of Ismative SHR blue (reactive dye) using a very cheap cement factory waste called by‐pass kiln dust has been investigated in batch mode. The effects of initial dye solution concentration, particle size, agitation rate, amount of by‐pass kiln dust, and dye solution temperature were studied. A 95.5 per cent removal was achieved. Some pretreatment of by‐pass kiln dust, such as washing by distilled water or rinsing with HCL solution, has been done. By using the washed by‐pass kiln dust the values of total dissolved solids, alkalinity, and efficiency of colour removal were reduced. A very rapid irreversible chemical reaction may occur in addition to the adsorption process. Ferric chloride was used as a coagulant after settling to complete the separation of the dust from the clear solution. A removal of 96 per cent from the initial colour of the industrial coloured wastewater was achieved.

Removal of chrome dye from carpet effluents using coal ‐ ii (rate processes)

Abstract The rate kinetics of adsorption of Omega Chrome Red ME (Mordant Red 19), a popular chrome dye often used in carpet industries, on coal has been studied. The kinetics of dye removal indicates the process to be diffusion controlled. A generalised empirical model is proposed for the kinetics at different initial concentrations. Correlations between intraparticle diffusion rate constant and initial concentration of dye and particle size of coal have been developed. Adsorbate film thickness at the surface of adsorbent is found to decrease with the rise of concentration, temperature of dye solution and coal particle size. The reduction in film thickness at higher temperature is indicative of the exothermic nature of the process, which was confirmed by the yield of negative heat of adsorption.

External mass transport processes during the adsorption of dyes onto bagasse pith

The kinetics of the adsorption of four dyestuffs onto bagasse pith has been studied. Two basic dyes, Basic Blue 69 and Basic Red 22, and two acid dyes, Acid Blue 25 and Acid Red 114, were used in an agitated batch adsorber. The effect of agitation, initial dye concentration, pith mass, pith particle size and dye solution temperature were investigated. A model is proposed to determine the external mass transfer coefficients, k f, for the systems and these are correlated with the system variable by the following equation: k f = A(variable) B.

Equilibrium studies during the removal of dyestuffs from aqueous solutions using Bagasse pith

The adsorption of four dyestuffs, namely, Basic Blue 69 (BB69), Basic Red 22 (BR22), Acid Red 114 (AR114) and Acid Blue 25 (AB25), onto bagasse pith has been studied. Bagasse pith is a cheap, abundant waste product from the sugar industry in Egypt and was found to have the following monolayer equilibrium saturation capacities: 158, 77, 23 and 22 mg dye g −1 pith. The effects of pith particle size range and dye solution temperature were studied. The equilibrium data were analysed using Langmuir, Freundlich and Jossens isotherms.

Adsorption of acid dye onto woodmeal by solid diffusional mass transfer

The adsorption of Telon Blue (Acid Blue 25) dye onto wood has been studied using an agitated batch adsorber. The variables studied include agitation, initial dye concentration, wood mass, wood particle size and dye solution temperature. Isotherms were measured and the isotherm parameters were determined. A mathematical model has been developed using the basis of the model proposed by Mathews and Weber Jr. This model is based on external mass transfer and solid-phase diffusion, and has been used to generate theoretical concentration—time decay curves. The results of the model were adjusted to the experimental data using a ‘best fit’ approach. The external mass transfer coefficient was found to vary with the degree of agitation, and consequently all other variables were considered at a constant agitation speed of 400 rev min −1. A good agreement between the theoretical generated and the experimental concentration—time decay curves was achieved using a constant external mass transfer coefficient, 0.30 × 10 −3 cm −1, and a constant solid-phase diffusivity, 0.200 × 10 −8 cm 2 s −1, for varying initial dye concentrations as well as wood mass. In experiments where the particle diameter was varied, a constant external mass transfer coefficient was sufficient to describe the system, but a decreasing diffusivity was required with increasing particle size. To simulate the effect of varying temperature, both external mass transfer coefficient and diffusivity were varied.

Adsorption of dyestuffs from aqueous solutions with activated carbon I: Equilibrium and batch contact‐time studies

AbstractThe ability of one activated carbon to remove dyestuffs from aqueous solutions has been investigated. The range of dyestuffs includes acidic, basic, disperse and direct dyes, and several factors have been studied, namely, agitation, initial dye concentration, adsorbent concentration, adsorbent particle‐size range, dye solution temperature, pH of solution and salt concentration.

Transport processes in the sorption of colored ions by peat particles

A three-step model has been proposed for the adsorption of Astrazone Blue dye (Basic Blue 69) on peat. The initial rate of uptake of dye ions due to physical adsorption and chemisorption (ion exchange) has been correlated using a surface mass transfer coefficient. These coefficients have been determined and expressed in the dimensionless mass transfer form, Sh Sc 0.33 , as a function of agitation, initial dye concentration, peat particle size range, dye solution temperature, and mass of peat.

The removal of colour from effluent using various adsorbents—III. Silica: Rate processes

The rate of adsorption of Astrazone Blue, a basic dye, on Sorbsil Silica has been studied. The parameters studied include particle size, initial dye concentration, agitation and dye solution temperature. The rate controlling step is mainly intraparticle diffusion, although a small boundary layer resistance is experienced. The activation energy for the adsorption of Astrazone Blue on silica is 13.2 ± 0.6 kJ kg −1. The diffusion coefficients vary from 9 × 10 −9 cm 2 s −1 at 20°C to 10 × 10 −8 cm 2 s −1 at 82°C.

Principles of dye removal from textile effluent

The initial rate of Disperse Blue 7 dye removal from textile effluent depends on the surface mass transfer coefficient. The effects of certain variables namely, agitation, initial dye concentration, particle size and solution temperature, on the dimensionless mass transfer term, Sh/Sc0.33, have been studied.

Allen Brands Receives Andrew Craigie Award

A newly isolated white-rot fungus named ZJSY, was isolated from the decayed mulberry branches using the method of decolorization zone. According to the morphological characteristics and sequence analysis of 18S rDNA, the strain was identified as Ceriporia lacerata. ZJSY was capable of decolorizing Congo red under the statically air-opened condition. Initial dye concentration, biomass dosage, temperature and initial pH of dye solution affected the decolorization rate. The optimum temperature and initial pH value for decolorization were 30 °C and 8, respectively. The decolorization rate could reach above 90% at 48 h when 3 g mycelia were added into 20 mL of Congo red solution with the concentration 0.1 mg mL−1. The decolorization was caused by both absorption of mycelia and degradation of enzymes mainly including manganese peroxidase (MnP) which could bio-transformed Congo red into naphthylamine and benzidine at 48 h. Toxicity test suggested the products at 48 h were more toxic than original dye. Overall findings showed that Ceriporia lacerate had good decolorization ability to Congo red and had well potential application prospects in the field of dye wastewater treatment.