Adsorption of Cationic and Anionic Dyes onto Commercial Kaolin (original) (raw)
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SN Applied Sciences
Presence of dye molecules in water causes various harmful effects for both human and aquatic species. Herein, we tried to remove two cationic dyes, namely Crystal violet and Brilliant green, from water by kaolinite clay mineral. The kaolinite clay mineral is further treated with 0.25 M and 0.05 M H 2 SO 4 to increase its adsorption capacity. The structural changes due to acid treatment were analyzed by XRD, zeta potential, FTIR, SEM, cation exchange capacity, BET surface area, and pore volume measurements. Kinetic data were analyzed by using five different kinetic models and the data fitted best to pseudo-second-order model. Langmuir isotherm showed best fit to the adsorption of both Crystal violet and Brilliant green. Acid-treatment has slightly increased the adsorption capacities for both the dyes. The Langmuir monolayer adsorption capacity of raw kaolinite was found to be 47.17 and 25.70 mg g −1 for Crystal violet and Brilliant green, respectively, which increased to 49.50 and 50.51 mg g −1 for 0.25 M and 0.50 M acid-treated kaolinite in case of Crystal violet and to 26.45 and 26.88 mg g −1 in case of Brilliant green at 303 K. Crystal violet adsorption was exothermic with increase in ∆G values, whereas Brilliant green adsorption was endothermic in nature with decrease in ∆G in the temperature range 293-323 K. Reusability study showed the adsorbents could be successfully used up to 3rd cycle without much loss of adsorption capacity.
Heliyon, 2020
In the present research, the kaolin adsorbents (beneficiated, raw powder, and calcined) were prepared from Ethiopian natural kaolin through mechanical, wet, and thermal processes. The geochemical and surface properties of kaolin adsorbent were characterized using FTIR, SEM/EDS, XRD, and XRF. In the batch experiment, basic operation parameters (initial dye concentrations, pH, temperature, contact time, and adsorbent dosage) were examined. Percentage removal efficiency basic yellow 28 (BY28) dye were recorded as 94.79%, 92.08%, and 87.08% onto beneficiated, raw, and calcined kaolin absorbents, respectively at an initial dye concentration of 20 mg/L, solution pH of 9, the temperature of 30 C C, and contact time of 60 min and adsorbent dosage of 1g/ 100L. The molar ratio of SiO 2 /Al 2 O 3 was recorded as 2.911 Percent mass composition of Ethiopian kaolin which is higher than the expected pure kaolinite standard which allows us to classify the kaolin clay as a siliceous one. The calculated values of ΔG 0 for beneficiated adsorbent are-1.243, 1.576, and 4.396 kJ/mol at 303.15, 323.15, and 343.15 K, respectively for 20 mg/L of dye concentration and solution pH of 9, suggests that the thermody-namic behavior at lowest temperature is more feasible and spontaneous as compared with the higher temperature one. A similar fashion was calculated for raw and calcined adsorbents. The negative values of ΔH o and ΔS suggest that the adsorption phenomenon is exothermic and the adsorbate molecules are organized on the solid phase in a more disordered fashion than the liquid phase. The pseudo-first-order and pseudo-second-order models have been used to describe the kinetics in the adsorption processes. The Pseudo-second-order model has been fitted for the BY 28 dye adsorption in the studied concentration range. The adsorption of BY 28 dye for raw and calcined adsorbents follows the Langmuir isotherm and the Freundlich isotherm fitted for the beneficiated adsorbent. The amount of BY28 dye taken up by beneficiated, raw, and calcined kaolin adsorbents was found as 1.896, 1.842, and 1.742 mg/g, respectively at a contact time of 1.0 h, the adsorbent dosage of 1.0 g, initial dye concentration ¼ 20 mg/L and solution pH ¼ 9 at 30 C. The results found that these raw and prepared local kaolin adsorbents have a capacity as low-cost alternatives for the removal of dyes in industrial wastewater.
DESALINATION AND WATER TREATMENT, 2018
In the present work, two Algerian clay samples, Djebel Debagh (DD3) and Tamazert (KT2), were used as adsorbents for the removal from the water of Derma Blue R67, which is an acid dye commonly used in the tanning industry. The two clay samples used were first treated by acid in order to enhance their retention capacities, and then characterized using X-ray diffraction, scanning electron microscopy, surface area measurements (Brunauer, Emmett et Teller method (BET)), surface charge (points of zero net proton charge), and electrophoretic mobility (Zetaphoremeter). Further, the adsorption experiments of the acid dye from water onto the clay surface were carried out by investigating various parameters such as, the contact time, the initial dye concentration, the aqueous phase pH, the clay amount and the temperature. The results indicate that the two adsorbents are efficient and that the anionic dye removal from water is mainly feasible at ambient temperature. Further, the comparison of the experimental adsorption data to the prediction models has shown that the Langmuir model gives the best fit, indicating the formation of a monolayer by the acid dye molecules on the clay surface. Finally, the adsorption kinetics follows a two-type process onto KT2 kaolinite, whereas onto DD3, it only follows the pseudo-second order model. From the overall data, it is concluded that the Algerian local kaolin clays are good adsorbent candidates for wastewater treatments.
Removal of cationic dyes by kaolinite
Microporous and Mesoporous Materials, 2009
The removal of cationic dyes such as maxilon yellow 4GL (MY 4GL) and maxilon red GRL (MR GRL) on kaolinite from aqueous solutions has been studied according to the adsorption method. The adsorbed amount of dyes on kaolinite surface was investigated as a function of pH, ionic strength, temperature, acid activation, and calcination temperature. It was found that: (i) the adsorbed amount of cationic dyes increased with increase in pH and decreased with increase in temperature, ionic strength, acid activation, and calcination temperature; (ii) the adsorption process was an exothermic process; (iii) the experimental data were correlated reasonably well by the adsorption isotherm of the Langmuir; and (iv) the interactions between adsorbate and adsorbent from adsorption heat data were physical in nature.
2017
The tanning industry, particularly the discharges from the dyeing process, induces environment pollution, causing hence human health problems. The treatment of the effluents by using low cost clays would have an important economic and environmental interest, as it would promote the local clays from the Algerian East. In the present work, we tested two Algerian kaolin clays, DjebelDebagh "DD3" and Tamazert “KT2”. These two clayswere firsttreated by acid in orderto enhance their retention capacities,and then characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), surface area measurements (BET method), surface charge (PZNPC), and electrophoretic mobility (Zetaphoremeter). The adsorption experiments were done using the Derma Blue R67 acid dye, commonly used in the tanning industry. The results showthat the adsorption is efficient and feasible at ambient temperature, and well described by the Langmuir model indicating a monolayer covering of the clay b...
2022
The effectiveness of thermal and acid modified locally available kaolin clay in Tanzania (Pugu clay), for removal of cationic dye from water systems were tested. The raw Pugu kaolin (RPK) was thermally-treated at 150oC for 7 hours and acid-leached with 0.2 M H2SO4 under reflux for 3 hours, to obtain thermally-activated Pugu kaolin (TAPK) and acid-activated Pugu kaolin (AAPK), respectively. The raw and modified clays were characterized by XRF, XRD, ATR-FTIR and Porosimeter for their mineralogical compositions, chemical compositions, specific surface areas and pore sizes. A comparative analysis of their respective adsorption efficiencies was carried out using basic blue 9 dye (BB9) as a representative adsorbate. The results revealed that while RPK was mainly composed of 44.18% silica and 26.70% alumina, the modified adsorbents had higher silica content of 46.95% and 58.81%; decreased alumina content of 24.11% and 12.74%, and increased surface areas from 15.36 to 41.07 m2/g and 149.61 ...
The textile effluents are considered as potential source of water contaminations. Thus the effective methods were adopted for the removal of dyes and colorants from the textile effluents. In the present research, the removal of textile dye Congo red was carried out by bentonite clay blend with kaolin. The kaolin-bentonite clay (KBC) was used as adsorbent. The adsorption properties of KBC towards Congo red were investigated, at various temperatures 303-318 ±2 K under the optimized conditions. The adsorption equilibrium data were fitted in Langmuir, Freundlich and Dubinin-Radushkevich adsorption isotherm models and the values of the respective constants were evaluated by employing standard graphical method. From the graph, it was founded that Langmuir model is the best fitted isotherm. Feasibility of adsorption process (RL) and sorption energy (Es) was also determined. The pH of adsorbent was estimated by pH drift method. Kinetics of dye removal was investigated that it follows pseudo second order rate constant. The surface morphology of adsorbent was observed by the Scanning Electron Microscope (SEM).
Arabian Journal of Geosciences, 2017
Clays, particularly kaolinite, are promising adsorbents for the treatment of textile effluents, but there is a need of better understanding the mechanisms of adsorption, especially in the case of anionic dyes. Thus, the removal of RR120 anionic dye was investigated using Tunisian raw clay (TBK) composed of kaolinite and illite, and a standard kaolinite (KGa-2), and conducting batch experiments by varying different parameters (contact time, ionic strength, concentration, temperature). We investigated the clays' surface charges by electrophoretic mobility measures and the dye-clay interactions during adsorption, by the streaming-induced potentials (SIP). The results showed that KGa-2 has higher adsorption capacity for RR120 dye than TBK clay, moreover enhanced by increasing the ionic strength and/or lowering the pH of the aqueous. The SIP results showed an increase of negative charges for both clays, reflecting the adsorption of the anionic dye on the positive charges of the amphoteric surfaces of the clays. The SIP magnitudes indicated a higher adsorption rate for KGa-2 in accordance with the kinetic study. The Sips model that described the best adsorption isotherms indicates lateral interactions of the dye molecules, stronger in the case of KGa-2 than TBK. Also, the dye molecules form a thinner layer on KGa-2 surfaces. In addition, the dye molecule's structure was not altered, as verified by mass spectrometry. The adsorption process was feasible and spontaneous and favored at ambient temperature. Thus, kaolinite-rich clays are effective in the removal of anionic dyes in aqueous solution and potential good adsorbents in wastewater treatment.
Raw kaolinite was used as a precursor for several types of modified kaolinite. The modification processes included modification by sodium hydroxide, sodium phosphate, sodium sulfate, CTAB, and sodium acetate. The structural, morphological, and chemical properties of raw kaolinite and the modified products were evaluated using XRD, SEM, TEM, and FT-IR analyses. The modified products were used as adsorbent materials for acidic Congo red dye from aqueous solutions. The adsorption processes were evaluated as a function of reaction time, initial dye concentration, and adsorbent masses. Phosphate-modified kaolinite achieved the best removal results followed by sulfate-modified kaolinite and kaolinite sample modified by CTAB. Kinetic studies indicated that the adsorption equilibrium was obtained after 360 min for the samples, which were modified by NaOH and CTAB, whereas the modified samples that were treated by phosphate, sulfate and, acetate achieve the equilibrium after 240 min. The adsorption by all the products is of chemical nature occurs through energetically heterogeneous surfaces and fitted well with pseudo-second order kinetic model. The equilibrium studies revealed that the adsorption using kaolinite modified by sodium hydroxide, sodium phosphate, and sodium sulfate occurs in monolayer form and represented well by Langmuir model. The estimated q max values are 136.98, 149.25, and 135.13 mg/g for the three products in order. The uptake using modified kaolinite by CTAB and sodium acetate shows more fitting with Tamkin and Freundlich isotherm models rather than with Langmuir model. Graphical Abstract Kaolinite sample was modified by organic and inorganic salts to enhance its adsorption properties. Modified kaolinite samples exhibit changes in the structural and morphological features. The modified samples showed high adsorption capacity than raw kaolinite. Highlights ● Kaolinite was modified by several inorganic and organic salts. ● Effect of modification and the structural and morphological features was investigated. ● The adsorption behavior of the modified products for Congo red dye was addressed. ● The change in the adsorption behavior was studied through kinetic and isotherm studies.
Adsorption of basic yellow dye dataset using Ethiopian kaolin as an adsorbent
Data in Brief, 2019
This article presents batch experimental data describing the main batch adsorption operation parameters. Also the adsorption models (adsorption isotherm, adsorption kinetics and thermody-namic studies) of basic yellow dye on to the raw and treated kaolin adsorbents. Besides, instrumental analyses were recorded to characterize kaolin adsorbent. Such as, thermogravimetric analyzer, Fourier transformation infrared and scanning electro-scope with energy dispersion spectroscopy were used. UVeVisible spectrometer was used throughout the experimental study for the determination of absorbance. The effect of adsorption temperature (30 C, 50 C 70 C), PH (3, 7, 9), initial dye concentration (20 mg/l, 40 mg/l, 60 mg/l), contact time (20 min, 40 min, 60 min, 80 min, 100 min) and adsorbent dosage (0.1, 0.5, 1, 1.5, 2 g/100ml) have been well determined. For adsorbent characteristics, we provide dataset regarding (i) thermogravimetery with differential scanning calorimetery, (ii) Fourier transform infrared spectral data before and after basic yellow dye adsorption process, (iii) scanning elec-troscope with energy dispersion spectroscopy image at Â500 resolution, (iv) X-ray diffraction and, (v) batch adsorption experimental parameters records. Regarding scanning electroscope with energy dispersion spectroscopy image, we provide data of three surface morphology image and three elemental distribution spectra for raw and treated kaolin adsorbent.