Kinetic, thermodynamic and equilibrium studies on the removal of copper ions from aqueous solutions by natural and modified clinoptilolites (original) (raw)
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Environmental Progress & Sustainable Energy, 2009
Clinoptilolite, a silica rich variety of the heulendite group of natural zeolites, has the capability to remove trace quantities of cations from aqueous solutions by utilizing the phenomenons of ion-exchange and adsorption. The aim of this study is to investigate the removal of copper ions from aqueous solutions by using the clinoptilolite samples. The results clearly showed that both conditioned and unconditioned forms of the clinoptilolized tuffs have a removal capacity up to 98–99% for low concentrations of metal ions. But the removal capacity decreases for the concentrations of about 500 mg/L when natural forms were used. The chemical conditioning has been found to increase the removal capability of the clinoptilolite to about 50%. The adsorption capacities of the unconditioned, conditioned, and reused forms of the clinoptilolite samples of Çankırı-Çorum Basin have also been investigated in this study. The results have been analyzed by Langmuir, Freundlich, Dubinin-Radushkevich (D-R), and BET (Brauner Emmett Teller) adsorption isotherms. Of the model tested, Langmuir, Freundlich, and D-R isotherm expressions were found to better fit the experimental equilibrium data compared with the BET model. © 2008 American Institute of Chemical Engineers Environ Prog, 2009
Removal of copper and cobalt from aqueous solutions using natural clinoptilolite
ABSTRACT Southern African clinoptilolite capability as an ion-exchanger with respect to Cu2+ and Co2+ was investigated in order to consider its possible application at removing metals from aqueous solutions. The column method was used in the cation-exchange processes with synthetic solution concentrations of 0.07 M (3.86 g/ℓ), 0.33 M (19.31 g/ℓ) and 0.66 M (38.63 g/ℓ) of Cu2+ solution and 0.07 M (3.34 g/ℓ), 0.33 M (16.69 g/ℓ) and 0.66 M (33.37 g/ℓ) of Co2+ solution. Synthetic non-mixed sulphate solutions of copper and cobalt recorded maximum cation uptakes of 79% and 63% with 0.02 M HCl-activated clinoptilolite respectively. From the Cu/Co mixed solutions, both cobalt and copper recorded a 79% uptake with 0.02 M HCl-activation. The 0.04 M HCl activation gave percentage removals of 79% and 77% for Co2+ and Cu2+ respectively. In the ion-exchange evaluation part of the study, it was found that in every concentration range, the adsorption mass ratio of clinoptilolite to metal concentration conformed to both Langmuir and Freundlich adsorption isotherms. However, the non-mixed aqueous solutions of Cu2+ and Co2+ fitted mainly the Langmuir equation. It was found that the adsorption process depends on the hydrated radius of the cation being exchanged, the concentration of the acid that activates the clinoptilolite and the concentration of the targeted cation in solution.
Water SA, 2010
Southern African clinoptilolite's capability as an ion-exchanger with respect to Cu 2+ and Co 2+ was investigated in order to consider its viability in the removal of metal cations from aqueous solutions. The effect of chemical conditioning was investigated using sodium chloride (NaCl), hydrochloric acid (HCl) and potassium chloride (KCl). The most efficient activating or conditioning reagent was found to be HCl at 0.02 M concentration, followed by KCl at 0.04 M and then NaCl at 0.04 M. The worst performing clinoptilolite was the original form under the conditions described in this study and it thus served as a control. The HCl-conditioned clinoptilolite was the most efficient in metal removal (79% Co 2+ and 73% Cu 2+) followed by the NaCl-conditioned form (69% Co 2+ and 54% Cu 2+), while the KCl-conditioned form adsorbed 54% and 73% of Co 2+ and Cu 2+ , respectively. The column method was used for the cation-exchange processes with synthetic solutions of 0.0020 M, 0.0698 M and 0.2000 M of Co 2+ and Cu 2+ concentrations which were measured using atomic absorption spectroscopy (AAS).
Use of Sorption of Copper Cations by Clinoptilolite for Wastewater Treatment
International journal of environmental research and public health, 2018
This paper from the field of environmental chemistry offers an innovative use of sorbents in the treatment of waste industrial water. Various industrial activities, especially the use of technological fluids in machining, surface treatment of materials, ore extraction, pesticide use in agriculture, etc., create wastewater containing dangerous metals that cause serious health problems. This paper presents the results of studies of the natural zeolite clinoptilolite as a sorbent of copper cations. These results provide the measurement of the sorption kinetics as well as the observed parameters of sorption of copper cations from the aquatic environment to the clinoptilolite from a promising Slovak site. The effectiveness of the natural sorbent is also compared with that of certain known synthetic sorbents.
Kinetics and thermodynamics study of copper ions removal by natural clinoptilolite
The process of removal of copper ions by means of clinoptilolite type natural zeolite has been studied as a function of the particle size and temperature. Results indicate that increase in temperature and decrease of particle size improves the removal of copper from aqueous solutions. The parabolic diffusion model is well described process in all examined range of time and it shows that the calculated diffusion coefficient increases with temperature. This increase is more visible at higher particle sizes what assume diffusion through zeolite particle as main mass transfer mechanism. The film diffusion model provides calculation of initial sorption rate (k´) and dimensionless parameter proportional to the diffusion film thickness (x i ), in relation of particle size and temperature. Diffusion from the surface of zeolite particles through the micro and macro pores is well described with homogenous diffusion model, where change of the calculated overall rate constant is observed at ≈60 min of the process. This indicates the change of mass transfer rate through porous zeolite particle.
Simultaneous removal of metals Cu2+, Fe3+ and Cr3+ with anions SO42− and HPO42− using clinoptilolite
Microporous and Mesoporous Materials, 2003
In the present study the effect of SO 2À 4 and HPO 2À 4 on ion exchange of Cu 2þ , Fe 3þ and Cr 3þ on natural clinoptilolite is examined under normality of 0.01 N, temperature of 25 AE 2°C and pH 2-2.5 after four days of equilibration. It is observed that Cu 2þ uptake is significantly decreased in the presence of HPO 2À 4 and SO 2 4. The observed effect is less significant for Fe 3þ and Cr 3þ in the presence of SO 2À 4 and HPO 2À 4 respectively. This could possibly be due to the metalanion complex formation and the nature and charges of the complex species present. Blank solutions show precipitation in the case of Fe 3þ /HPO 2À 4 solution, leading in complete removal of Fe 3þ from solutions. Precipitation along with ion exchange is resulting in higher removal of Fe 3þ from the solution than ion exchange or precipitation alone. Finally, anion co-removal is significant, reaching 80% for HPO 2À 4 ions.
Synthesis of a clinoptilolite–Fe system with high Cu sorption capacity
Chemosphere, 2007
An iron oxide-clinoptilolite system was synthesized by adding natural clinoptilolite in an iron nitrate solution under strongly basic condition. The newly synthesized material has a red-brown color. A combination of XRD, FTIR and EPR spectroscopies, as well as specific surface area measurements and TG/DSC thermal analyses provided information on the type of Fe species located on the zeolite surface. Clinoptilolite seems to maintain its structure, while Fe 3+ species are in a symmetric environment (Th or Oh). The new material has a noteworthy high value of specific surface area (151 m 2 g À1) and is fully iron exchanged (Fe/Al = 1.23). Differences in FTIR and TG/DSC spectrograms between the Fe-Clin system and untreated Clin were reported and explained. According to Cu adsorption/ desorption experiments, carried out after the synthesis and characterization procedures, the Fe-Clin system is a promising new material since it adsorbs significantly larger Cu concentrations than clinoptilolite. This fact is owed to its high specific surface area and to its high negative surface charge. Desorption of Cu was also examined and it was observed that the Fe-Clin system desorbs smaller Cu amounts than untreated clinoptilolite.
International Journal of Environmental Research, 2013
Considering the point that the existence of heavy metals in the wastewater are so dangerous forthe environment and it would have many bad consequences for all the creatures including human beings, wemust try out the ways that make us capable of adsorbing these heavy metals. In order to accomplish this goal we should use a method called adsorbing. In this study the adsorption of copper ions in hydrated copper nitrate (Cu (NO3)2, 3H2O) aqueous solution on natural zeolite (Clinoptilolite) and vermiculite was studied in batch reactors. The effect of temperature (25, 50, 75 °C), solution pH (1.00-5.5) and concentration effect on the traditionally defined adsorption isotherm in the adsorbate range 100-325 mg/L for clinoptilolite and 100- 650 mg/L for vermiculite on the removal of copper was studied. The results showed that an increase in pH increases the adsorptivity of vermiculite. Pseudo second order model best described the reaction rate. Batch adsorption experiments conducted at room ...
Water Research, 2009
Zeolites have been widely used in water treatment and especially clinoptilolite, due to its low cost and high abundance. It has large cation-exchange capacity and is capable of removing large quantities of heavy metals from contaminated water samples. By loading the surface of clinoptilolite with amorphous Fe-oxide species, a total improvement in adsorption capacity could be achieved. Thus, the Clin-Fe oxide system is capable of adsorbing significantly higher heavy metal concentrations than untreated clinoptilolite with simultaneous noticeable decrease in water hardness. Batch adsorption experiments have shown that Clin-Fe system has very large Cu, Zn and Mn adsorption capacity and for most of the cases the treated water samples were suitable for human consumption or agricultural use. New experiments were conducted to study the effectiveness of clinoptilolite and of the Clin-Fe system in removal of Cu, Mn, Zn, present simultaneously in water samples, so that the study of metal-sorbent chemical behavior and of the adsorption selectivity would be feasible. Desorption of metals was also examined and an integrated approach of the effectiveness of such materials in drinking water treatment is presented.
Binary Adsorption of Copper and Sulfates on Barium-Modified Clinoptilolite
2018
The binary adsorption of copper cations and sulfate anions by surface modified natural clinoptilolite was investigated. The efficiency of the adsorbent was studied using batch adsorption technique under different experimental conditions by varying parameters such as initial ions concentration in the aqueous solution, clinoptilolite mass and contact time. An assessment of the equilibrium and the kinetics of copper and sulfates ions sorption was made. The experimental results were fitted to the Freundlich, Baudu, and the Multilayer isotherms. It was established that the Baudu isotherm best describe the binary removal of Cu2+ and SO4 2by modified clinoptilolite with incorporated barium ions on its surface (CLIBa). Before the clinoptilolite modification (CLI), the removal of both copper and sulfate ions was best described by Baudu and Multilayer isotherms, respectively. The removal of Cu2+ is probably due to physiosorption, while that of SO4 2to at least two different in nature mechanis...