Adsorption of anionic dyes onto natural, thermally and chemically modified smectite clays (original) (raw)
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Removal of Direct Dyes from Wastewater by Sorption Onto Smectite-Clay
2010
Dyes and pigments are important organic pollutants of the water environment. Dyes may be removed from wastewater by using one of the most efficient methods for wastewater treatment-adsorption onto porous (natural and waste) minerals or organogenic substances. Feasibility of using smectite-clay, co-occurring in brown coal deposits, for removal of direct dyes was investigated. The Freundlich linear regression model was better in modeling of sorption direct dyes onto smectite-clay; it yielded better fit of the theoretical isotherm to the experimental data. The electrostatic interactions and hydrogen bonds were shown to play the most important role in adsorption of direct dyes onto smectite-clay.
Experimental study and modeling of basic dye sorption by diatomaceous clay
Applied Clay Science, 2003
This paper presents a study on the adsorption of basic dye, methylene blue, from an aqueous solution onto diatomaceous earth (diatomite). The effect of initial dye concentrations, adsorbent particle size and concentration, and agitation speed on adsorption was investigated. Adsorption isotherms obtained at different solutions temperatures revealed an irreversible adsorption with a capacity of 42 mmol dye/100 g diatomite reached within 10 min. This value slightly increases with increasing the solution temperature. A proposed correlation to describe the irreversible adsorption isotherm was introduced, which resulted in a better fit to the experimental data than that of Langmuir's and Freundlich's. Two simplified kinetics models, pseudo-first order and pseudo-second order, were tested to investigate the adsorption mechanisms. It was found that the kinetics of adsorption of methylene blue onto the surface of diatomite at different operating condition are best described by the pseudofirst-order model. D
11.[30-39]Sorption Kinetics for Dye Removal From Aqueous Solution Using Natural Clay
The kinetics of the adsorption of Congo red onto natural clay has been studied in an agitation batch adsorber. The Furusawa model has been used to determine the external transfer coefficient for the system and the effect of several experimental variables have been investigated: these include agitation, initial dye concentration, clay mass and clay particle size. The mass transfer coefficient has been correlated with the system variable by the following equation: k f = A(variable) B .
Adsorption of an anionic textile dye from wastewater by bentonitic clay mineral
Surface Engineering and Applied Electrochemistry, 2016
In this paper, adsorptive performance of natural clay has been investigated as a potential reactive dye adsorbent, on the basis its promising physical-chemical and morphological properties which were compared to several previous works. Sample used in this work, collected from Grombalia (North-East of Tunisia), has been characterized at the first time. Following its physicochemical study, this sample has been employed and tested as an ion exchange medium, for an anionic toxic textile dye removal from textile effluent and watercourse. Physicochemical experiences confirm that the used clay mineral was a clay of bentonite type having the following structure formula Ca 0.014 Na 0.404 K 0.16 (Si 7.65 Al 0.35)(Al 2.910 Fe 0.762 Mg 0.376)O 22. Dye removal from aqueous solution onto raw (GRb) and purified (GRp) bentonite was investigated, using a batch adsorption technique, as a function of various parameters such as initial dye concentration, contact time, temperature and pH medium. Results prove that the amount of dye removed by the raw and the purified bentonite was found to be around 142 and 294 mg/g respectively. According to previous works this quantity of dye removed from aqueous solution (294 mg/g) reach the anionic exchange capacity of bentonitic sample. A contact time (clay/dye solution) of 20 to 30 min was sufficient to reach adsorption equilibrium. Adsorption rate was fast, more than half of the adsorbed dye was removed from the aqueous solution (C = 10-4 M). The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms. Experimental data fit well with Freundlich model (the correlation coefficients, R 2 , was found to be equal to 0.98).
Journal of Environmental Health Science and Engineering, 2020
Context Textile industries discharge large amounts of untreated colored wastewater into ecosystems which have adverse effects on the human, living and aquatic environment. The aims of this study were: upgrading and testing the brewery waste adsorption affinity towards BEMACID red (B-R), BEMACID yellow (B-Y) and BEZAKTIV black (B-B), verified the effect of linear form modeling on adsorption parameters values and to find the limiting kinetic step in adsorption process. Methods The adsorption efficiency of brewery waste towards three textile dyes: BY , B-R and B-B is tested. The evolution between the adsorption capacity and the operating conditions such as: pH solution, adsorbent mass, contact time and initial dye concentration is determined by kinetics measurements. Effect of a form of pseudo-first order, six forms of pseudo-second order, a form of intra-particle diffusion and a form of external mass transfer diffusion are tested to the prediction of kinetic parameters and to find the limiting kinetic step. In order to modeling the equilibrium data, a form of Freundlich and five forms of Langmuir isotherms are tested. The residual concentration of dye in solution was measured by spectrophotometer. Scanning Electron Microscope (SEM) was using to investigate the structure of raw adsorbent. Results The results of kinetics measurements show that the perfect adsorption operating conditions are: acidic medium for all dyes (pH = 2 and pH = 3), low mass adsorbent (m = 40 mg), equilibrium time t = 40 min and for initial concentration of 250 mg/L. Also the results prove that the adsorption mechanism is controlled by both steps of diffusions (interne and extern diffusion) and fitted well by the first and the second linearized form of pseudo-second order model with correlation coefficient R 2 = 0.99. The results of isotherms modeling show that the second and the third linearized forms of Langmuir giving the best removed amount for BY equal 200 and 219.4 mg/g respectively compared to others linearized forms. Conclusion In summary, the effect of linear forms used either in the medellization of isotherms or kinetic data is significant in the prediction of adsorption parameters, also brewery waste has a significant BY dye adsorption affinity compared to others dyes, the descending order of maximum adsorption capacity finding is: qe = 209 mg/g for BY , qe = 152 mg/g for B-R and finally qe = 108 mg/g for B-B.
Sorption equilibrium of selected azo dyes onto low-cost sorbents
In the paper, equilibrium of sorption of s elected azo dyes onto natural sorbents was studied. The sorbents included birch chips, rye straw, hemp fiber and cellulose. The materials were first subjected to initial heat and chemical processing. Sorption studies were carried out for selected azo dyes, i.e. Reactive Blue 81, Reactive Red 120, Direct Black 22 and Direct Orange 26. An advanced examination under infrared light was performed for the analysed systems, which allowed for the determination of the nature of the dye-sorbent bond. In most cases, the bonds were a result of physical adsorption on the surface and in the micropores of the material.
ADSORPTION OF DYES ON MINERAL SURFACES: A STUDY OF ADSORPTION CAPACITY OF PHYLLOSILICATES
Natural northern Moroccan clay was used for the removal of basic dye, methylene blue dye (MB). dynamic and equilibrium data were obtained by the batch technique. The dynamic data indicate that this natural clay was good for basic dye due to its high surface area for adsorption for MB dye. The adsorption process was analyzed in terms of two tree state equations and the intraparticle diffusion model. The adsorption isotherms of Langmuir and Freundlich as well as Temkin types were employed to examine the equilibrium adsorption data. Results show that all the adsorption systems could be adequately fitted by the Langmuir equation. Thermodynamic parameters were also obtained. KEYWORDS: Moroccan clay, adsorption, methylene blue, kinetic models.
Adsorption of Basic Dyes onto Natural Clay
Adsorption Science & Technology, 2004
The adsorption ability of natural clay towards the removal of basic dyes from aqueous textile solutions was investigated. The equilibrium isotherms were measured and analyzed using the Langmuir model and the experimental results compared with the theoretical data. The adsorbent exhibited considerable adsorption capacities of 567, 526, 427 and 300 mg/g towards Neutral Red, Methyl Violet, Methyl Green and Methylene Blue, respectively. Thus, the clay may be used as a cost-effective industrial adsorbent for the removal of basic dyes from industrial effluents.
In the study, montmorillonite was used as an adsorbent for the removal of methylene blue (MB) from aqueous solutions. Batch studies were performed to address various experimental parameters like contact time, pH, temperature, stirring speed, ionic strength, adsorbent dosage and initial concentration for the removal of this dye. Adsorption rate increased with the increase in initial dye concentration, ionic strength, stirring speed, pH and temperature. Kinetic study showed that the adsorption of dye on montmorillonite was a gradual process. Quasi-equilibrium reached in 3 h. Pseudo-first-order, pseudo-second-order, Elovich, Bangham, mass transfer and intra-particle particle diffusion models were used to fit the experimental data. Pseudo-second-order rate equation was able to provide realistic description of adsorption kinetics. Intra-particle diffusion process was identified as the main mechanism controlling the rate of the dye sorption. The diffusion coefficient, D, was found to increase when the stirring speed, ionic strength and temperature were raised. Thermodynamic activation parameters such as ΔG*, ΔS* and ΔH* were also calculated.
Evaluation of adsorption potential of adsorbents: a case of uptake of cationic dyes
Journal of environmental biology / Academy of Environmental Biology, India, 2008
Adsorption potential of a commercial activated carbon (FS300) has been evaluated for the uptake of cationic dyes namely methylene blue (MB) and rhodamine B (RB). Though, there are numerous studies in literature which report the sorption of MB (more than 40 studies) and RB (more than 10), however none of these use a common parameter to report the capacity of the sorbent. A protocol, based on the equilibrium dye concentration has been proposed to measure the sorption potential of a sorbent. The Langmuir model can very well describe the experimental equilibrium data for both dyes (coefficient of correlation > 0.999). MB (Qm = 312.5 mg g(-1)) is more adsorbable than the RB (Qm = 144.9 mg g(-1)). Molecular weight and chemical structure of dye molecules seem to affect the dye uptake. The effect of pH on dye uptake has also been evaluated by varyingpH from 3 to 11. Uptake of MB increases with pH, wherein RB removal decreases with pH. Dyes could not be desorbed either by distilled water ...