Adsorption of Fe(III) from water by natural and acid activated clays: Studies on equilibrium isotherm, kinetics and thermodynamics of interactions (original) (raw)
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Applied Clay Science, 2009
Kaolinite and montmorillonite were modified with tetrabutylammonium (TBA) bromide, followed by calcination. The structural changes were monitored with XRD, FTIR, surface area and cation exchange capacity measurements. The modified clay minerals were used for adsorption of Fe(III), Co(II) and Ni(II) ions from aqueous solution under different conditions of pH, time and temperature. The uptake of the metal ions took place by a second order kinetics. The modified montmorillonite had a higher adsorption capacity than the corresponding kaolinite. The Langmuir monolayer capacities for the modified kaolinite and montmorillonite were Fe(III): 9.3 mg g − 1 and 22.6 mg g − 1 ; Co(II): 9.0 mg g − 1 and 22.3 mg g − 1 ; and Ni(II): 8.4 mg g − 1 and 19.7 mg g − 1 . The modified kaolinite interacted with Co(II) in an endothermic manner, but all the other interactions were exothermic. The decrease of the Gibbs energy in all the cases indicated spontaneous adsorption.
Ife Journal of Science, 2021
In this paper, Fe2+ , Pb2+ , Zn2+ and Cr6+ ions removal from contaminated water with natural Nigerian kaolinite clay (AK-clay), and that removed with kaolinite clay modified with either ammonium oxalate (AK-AO) or sodium hydroxide (AK-S) were presented. The clay was characterized using X-Ray Diffractometry (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Brunanuer-EmmettTeller (BET) method. The parameters investigated include pH, adsorbent particle size, shaking speed, metal ion concentration and temperature. The optimum conditions were applied to the modified samples. Design-expert software was used to design the experimental conditions using Response Surface Methodology (RSM). The mineralogical characterization showed the purified 63 µm fraction of the clay as kaolin. Analysis of Variance shows the adsorption of the metal ions was statistically significant with p-valves > 0.0001 at 95 % confidence limit. Pseudo second-order kinetic m...
Separation Science and Technology, 2017
Water pollution by heavy metal ions has become a serious environmental issue especially due to their toxicity and tendency to bioaccumulation. Natural smectite clay was treated using sulfuric acid to improve its adsorption capacity for the removal of iron ions from aqueous solutions. The results showed that adsorption was favoured at pH 3 and room temperature. Experimental adsorption capacity of Fe(III) is 12.86 mg/g and 19.25 mg/g for natural and acid-activated clay, respectively. From all of our data, we conclude that the treated clay by sulfuric acid investigated in this study showed a good potential for iron removal from aqueous solutions.
Enhancement of the adsorption capacity of Fe-clay by bioleaching and activation of Fe sites
Applied Clay Science, 2018
This study presents how the bioaccessibility and biotransformation of Fe-oxides present in two different Fe rich clay samples influenced their sorption properties. The bentonite and kaolin were bioleached by heterotrophic indigenous bacteria for 15 and 30 days and following treated by 1 M and 6 M hydrochloric acid. By bioleaching, only slight content of Fe was removed from the natural samples, but content of hardly soluble Fe oxides decreased and amorphous oxide-hydroxide increased. This transformation related with decrease in value of specific surface area and total pore volume, as well as with morphological and pore changes of studied clays. After 30 days of bioleaching process, bioleached samples proved better adsorption parameters for the As V and Sb V adsorption in comparison to natural samples. The sorption efficiency of As V /Sb V adsorption on bioleached materials reached up to 95-99%, at which the bentonite was more sensitive to bioleaching.
SORPTION OF Fe IONS IN AQUEOUS MEDIUM BY LATERITE CLAY: A STUDY OF pH DEPENDENCY
Laterite soil was found to be an essential material for ion sorption from aqueous solutions. This study focuses on investigating the pH dependency on sorption of Fe ions using laterite by a series of batch experiments. Basic physical and chemical parameters of laterite were measured to characterize the material. The X-ray diffraction (XRD) analyses of laterite show goethite, gibbsite, and hematite as the major secondary minerals with minor occurrences of kaolinite. In the experimental design, 20 g/L adsorbate of raw laterite was used for each batch reaction. In each experiment, a 100 ml of Fe solutions (40 ppm) was reacted with the adsorbate under a range of pH levels (1-9). Samples were analyzed for removal performances at different intervals for a five-hour reaction time. Results revealed that under acidic conditions (pH < 5), Fe removal efficiencies were very low (< 1.5 %) even after 5-hours, and Fe removal efficiencies from slightly acidic to neutral pH (5 ≤ pH ≥ 7) showed diverse variation (1.5 ≤ efficiency ≥ 100 %). However, under the basic condition (pH ≤ 7), very high Fe removal efficiencies (80-100 %) were reached within a short time. The experiment further revealed that no leaching of similar behavioral elements such as Zn, Cu, Ni, Cd, and Mn from laterite to solution occurred during the Fe sorption, which may indicate absence of iron exchange activities. Results concluded that the duration of reaction time has a strong relationship with the removal performances from acidic to basic conditions and highly acidic conditions promote dissolution of Fe ions from laterites, while basic pH facilitates the sorption.
The uptake mechanism and influence of iron (Fe) co-adsorption on the binding of rare-earth elements (REEs) on kaolinite have been investigated. REEs and varying concentrations of Fe were co-adsorbed onto kaolinite at pH 10.5. Inductively coupled plasma mass spectrometry (ICP-MS), powder X-ray diffraction (PXRD), and X-ray photoelectron spectroscopy (XPS) were used to characterize how Fe co-adsorption influenced the uptake mechanism of REEs on kaolinite. Elemental analysis by ICP-MS revealed that the REE concentrations on kaolinite were unaffected by the presence of Fe. Crystal structure of kaolinite, determined by PXRD, was not altered after REE and Fe co-adsorption. XPS suggests that the adsorbed Fe is in the form of FeOOH, while the greatly attenuated REE XPS signals upon Fe co-adsorption implies that REEs are encapsulated by Fe species. Based on these results, we conclude that FeOOH layers were formed on top of REEs on the surface of kaolinite. Synthesized REE-Fe-kaolinite samples respond poorly to ion-exchange leaching, indicating that Fe is detrimental to the REE ion-exchange efficiency. The inhibition of ion-exchange REE extraction appears to be due to the passivating FeOOH layers. In contrast to ion-exchange methods, reductive leaching was found to dissolve the FeOOH passivating layers and liberate REEs such that they became available for ion-exchange leaching.
Adsorption of Some Heavy Metal Ions from Aqueous Solutions by Using Kaolinite Clay
Adsorption of some heavy metal ions such as lead, Pb(II), Copper, Cu(II), Iron, Fe(III), Manganese, Mn(II) and Zinc, Zn(II) by sorption on kaolinite clay was investigated. Kaolinite clay is considered as a good ion exchanger since it is easily available at low cost and high capacity. The effects of contact time, pH, volume of an aqueous to mass of kaolinite clay and concentration of metal ions were studied. Data show that kaolinite clay favorably adsorbs the current heavy metal ions and their adsorption are belong to Freundlich isotherm model.
Treated Clay Mineral as Adsorbent for the Removal of Heavy Metals from Aqueous Solution
Applied Science and Engineering Progress, 2021
The decontamination of heavy metals present in aquatic bodies is a significant challenge that requires urgent attention. Analytical methods such as BET, XRF, SEM-EDX, and XRD was employed to characterize the raw clay (NT) and acid treated clay (AT). The adsorption of Cr (VI) and Fe (III) onto AT was performed using the batch method. The effects of time, adsorbent dose, temperature, and pH show that the optimal conditions are 50 min, 0.3 g, 35°C, and pH 6. The surface area of AT was 389.37 m2/g, and the adsorption equilibrium time of AT was 50 min. Langmuir isotherms had the best fit. Adsorption capacity is 18.15 and 39.80 mg/g for Cr (VI) and Fe (III) ions, respectively. An increase in area considerably improved the adsorption capacity of AT in the surface specific area. The interaction of Cr (VI) and Fe (III) ions onto AT indicated spontaneous and endothermic reaction. The chromium (VI) kinetic constant (k2 = 1.679) was faster compared to Fe (III) rate constant (k2 = 0.0526). It ag...
Separation and Purification Technology, 2006
Adsorption of metals by clay minerals is a complex process controlled by a number of environmental variables. The present work investigates the removal of Cu(II) ions from an aqueous solution by kaolinite, montmorillonite, and their poly(oxo zirconium) and tetrabutylammonium derivatives. The entry of ZrO and TBA into the layers of both kaolinite and montmorillonite was confirmed by XRD measurement. The specific surface areas of kaolinite, ZrO-kaolinite, TBA-kaolinite, montmorillonite, ZrO-montmorillonite, TBA-montmorillonite were 3.8, 13.4, 14.0, 19.8, 35.8 and 42.2 m 2 /g, respectively. The cation exchange capacity (CEC) was measured as 11.3, 10.2, 3.9, 153.0, 73.2 and 47.6 meq/100 g for kaolinite, ZrOkaolinite, TBA-kaolinite, montmorillonite, ZrO-montmorillonite, TBA-montmorillonite, respectively. Adsorption increased with pH till Cu(II) ions became insoluble in alkaline medium. The kinetics of the interactions suggests that the interactions could be best represented by a mechanism based on second order kinetics (k 2 = 7.7 × 10 −2 to 15.4 × 10 −2 g mg −1 min −1 ). The adsorption followed Langmuir isotherm model with monolayer adsorption capacity of 3.0-28.8 mg g −1 . The process was endothermic with H in the range 29.2-50.7 kJ mol −1 accompanied by increase in entropy and decrease in Gibbs energy. The results have shown that kaolinite, montmorillonite and their poly(oxo zirconium) and tetrabutyl-ammonium derivatives could be used as adsorbents for separation of Cu(II) from aqueous solution.
Role of iron oxides in the phosphate adsorption properties of kaolinites from the Ivory Coast
The phosphate adsorption properties of three clay samples, with kaolinite as the dominant mineral, from different deposits in the Ivory Coast have been investigated. The clays contain varying amounts of crystalline Fe oxides and kaolinite with structural Fe. All measurements were made in dilute suspension under controlled conditions of temperature, pH, ionic strength and saturating cation. Data have been fitted to Langmuir adsorption isotherms. Both P adsorption and surface area measurements have been made on samples before and after chemical removal of Fe oxides. The samples have large P adsorption capacities, which are not entirely explained by their large specific surface areas. The presence of Fe oxides makes a strong contribution to the surface area and enhances the adsorption capacities. There is little evidence that structural Fe makes a strong contribution to the enhanced P adsorption capacity.