Adsorption of benzene and naphthalene to modified montmorillonite (original) (raw)
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Journal of Chemistry, 2013
Multicomponent adsorption of benzene, toluene, ethylbenzene, and xylene (BTEX) was assessed in aqueous solutions by montmorillonite modified with tetradecyl trimethyl ammonium bromide (TTAB-Mt). Batch experiments were conducted to determine the influences of parameters including loading rates of surfactant, contact time, pH, adsorbate concentration, and temperature on the adsorption efficiency. Scanning electron microscope (SEM) and X-ray diffractometer (XRD) were used to determine the adsorbent properties. Results showed that the modification of the adsorbent via the surfactant causes structural changes of the adsorbent. It was found that the optimum adsorption condition achieves with the surfactant loading rate of 200% of the cation exchange capacity (CEC) of the adsorbent for a period of 24 h. The sorption of BTEX by TTAB-Mt was in the order ofB
Chemical Engineering Journal, 2012
The adsorption characteristics of benzene, toluene, ethylbenzene and xylene (BTEX) from aqueous solutions by montmorillonite (Mt) modified with poly ethylene glycol (PEG-Mt) were investigated. The batch adsorption technique was used to assess the influence of various parameters such as loading rates of the surfactant, contact time, pH, adsorbate concentration, solution ion strength and temperature on the BTEX sorption capacity by PEG-Mt. The raw and modified Mt was specified with X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The XRD results showed that the interlayer spacing of the raw montmorillonite (12.10Å) was increased by PEG surfactant modification (17.48Å). The adsorption capacity of the PEG-Mt was increased by increasing the surfactant loading until 200% cation exchange capacity (CEC) of the clay. The equilibrium was achieved at the contact time of 24 h. The adsorption capacity of the adsorbent was in order of B < T < E < X. The experimental data were analyzed by Langmuir, Freundlich and D-R isotherm models. The results indicated that the data were best fitted with the Freundlich isotherm. The D-R isotherm model also showed that the adsorptive behavior of these compounds has physical nature. The obtained data for BTEX adsorption onto the PEG-Mt were also fitted through the pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. The correlation coefficients values (R 2) showed that the adsorption kinetic described well by the pseudo-second-order model. The thermodynamic study also indicated that the uptake of BTEX by the adsorbent was spontaneous, endothermic and favorable at higher temperatures.
Water, Air, & Soil Pollution, 2016
Benzalkonium chloride (BAC) loaded to montmorillonites (Mt) or organomontmorillonites (OMt) generates a functional material that can be incorporated to several systems (polymers, paints, etc) as a controlled release bactericide. Understanding the BAC adsorption sites on these adsorbents is of high importance to clarify their adsorption/desorption characteristics in aqueous media or other solvents. In this work, a thorough study about the adsorption/desorption properties of Mt and OMt with regards to BAC is presented, in order to evaluate further BAC release with the consequent aquatic environment contamination. In this work, the BAC adsorption on two different sites is demonstrated: the interlayer space and the external surface. Depending on BAC concentration in water, sorption of BAC at Mt occurred in two steps. At adsorbed amount <0.5 mmol g −1 , there was an Mt interlayer expansion of 0.49 nm with no change of the external charge. At adsorbed amount >0.5 mmol g −1 , there was a new interlayer expansion attaining 0.75 nm and the external charge shifted to positive value. In the case of OMt, the introduction of BAC produced changes in the interlayer structure and in the external surface charge. BAC desorption was strongly dependent on the type of Mt or OMt and extraction solvent, knowledge of which will allow its safe use in environmental friendly technological applications.
International Journal of Environment and Health, 2014
Pesticides, heavy metals and surfactants can share the same region or site in the environment and thus they may compete for the surface of minerals. A competitive study of the adsorption between the cationic surfactant benzalkonium chloride (BAC) with the heavy metal cadmium (Cd(II)) and the cationic herbicide paraquat (PQ) on montmorillonite is presented. Adsorption isotherms for BAC, PQ and Cd(II) were performed in single solute systems and also in binary solute systems, PQ+BAC and Cd(II)+BAC to evaluate the effects of BAC on the adsorption of the other two substances. The affinities of BAC and PQ were strong and similar, thus BAC affected significantly the adsorption of PQ and vice versa. The affinity of Cd(II) for the montmorillonite surface was low, thus BAC affected appreciably Cd(II) adsorption, but the heavy metal did not modify BAC adsorption. XRD data show that BAC molecules control the magnitude of the basal spacing.
Clays and Clay Minerals, 1997
The adsorption of the monovalent organic cations benzyltrimethylammonium (BTMA) and benzyltriethylammonium (BTEA) to montmorillonite was studied as a function of their concentrations and ionic strength. At low ionic strength the adsorbed amounts of BTMA and BTEA reached values of the cation exchange capacity (CEC) of the clay. An increase in the ionic strength resulted in reduction in the adsorbed amounts of the organic cations, unlike the pattern observed previously with organic monovalent cationic dyes. The reduction in adsorbed amounts of BTMA and BTEA depended on the inorganic cations according to the sequence Cs + > Na + > Li +, which follows the sequence of binding coefficients of these inorganic cations added. The type of the anion (that is, C1 , C104-, SO4 z) had no effect on the adsorbed amounts. An adsorption model which considers the electrostatic Gouy~Chapman equations, specific binding and closeness of the system could adequately simulate the adsorbed amounts of BTMA and BTEA and yield predictions for the effect of the ionic strength and concentration of electrolytes. The binding coefficient employed was K = 5000 M ~ for the formation of neutral complexes of BTMA and BTEA. This value is larger than those found for the inorganic cations but is several orders of magnitude below those found for the monovalent dyes. The binding coefficients for the formation of charged complexes of BTMA and BTEA were 20 and 5 M ~, respectively. The basal spacing of the clay did not change significantly with the adsorbed amounts of both BTMA and BTEA up to the CEC.
Adsorption kinetics of naphthalene onto organo-sepiolite from aqueous solutions
Desalination
In this study, the adsorption kinetics of naphthalene onto organically modified-sepiolite was investigated by means of the effects of pH, contact time, adsorbent dosage and temperature. The modification of natural sepiolite was accomplished with a cationic surfactant, which is namely dodecyltrimethylammonium (DTMA) bromide. The surface characterization both natural- and modified-sepiolite were carried out by using FTIR method to observe the intercalation of DTMA between the sepiolite layers. The elemental and thermal analyses were also performed to understand the modification. The optimum pH values and the equilibrium contact time for the adsorption of naphthalene onto DTMA–sepiolite were found as 6 and 75 min, respectively. The kinetic parameters of the adsorption process were calculated from experimental data. According to these parameters, adsorption process follows the pseudo-second-order kinetic model with the high correlation coefficients (r2 = 0.999). The obtained results sho...
2013
Contamination of aromatic compounds in water can cause severe long-lasting effects not only for biotic organism but also on human health. Several alternative technologies for remediation of polluted water have been attempted. One of these is adsorption process of aromatic compounds by using organic modified clay mineral. Porous structure of clay is potential properties for molecular adsorptivity and it can be increased by immobilizing hydrophobic structure to attract organic compounds. In this work natural montmorillonite were modified with cetyltrimethylammonium (CTMA+) and was evaluated for use as adsorbents of aromatic compounds: benzene, toluene, and 2-chloro phenol in its single and multicomponent solution by ethanol:water solvent. Preparation of CTMA-montmorillonite was conducted by simple ion exchange procedure and characterization was conducted by using x-day diffraction (XRD), Fourier-transform infra red (FTIR) and gas sorption analysis. The influence of structural modifica...
Journal of Colloid and Interface Science, 1999
The adsorption of the cationic surfactant BDDAC on a hydrophilic smectite (montmorillonite) surface has been investigated, especially in the range of low coverage ratios where surfactant ions are adsorbed through cation-exchange with the counterions of the clay. The surfactant coions (Cl ؊ ) were found to be adsorbed simultaneously with the cationic part after a complete alkyl ammonium ion-exchange of montmorillonite (CEC). We observe that organoclay particles remain flocculated in aqueous medium in almost all the range of adsorption isotherms up to 1.38 CEC and afterward redisperse incompletely. The intercalation of surfactant in the interlamellar space was followed by X-ray measurements. Fluorescence spectroscopy was used to obtain information about the adsorption layer at the interface. A calculation from geometrical considerations and from adsorption isotherms shows that below 1.38 CEC, there is a flat double layer in the interlamellar space and after this amount of adsorbed surfactant, an interstratified clay-surfactant mixed system is formed.
Adsorption of Naphthalene on Clay and Sandy Soil from Aqueous Solution
The adsorption behavior of naphthalene using clay and sandy soil as adsorbents is examined under ambient conditions. The adsorption equilibrium of naphthalene on clay and sandy soil was evaluated by the Langmuir, Freundlich and Tempkin isotherms. The results showed that the equilibrium data for naphthalene fitted the Freundlich model best within the concentration range studied for both clay and sandy soil. Experimental results showed that the time taken to attain adsorption equilibrium for naphthalene was 26 hrs and 20 hrs for clay and sandy soil, respectively. Among the tested kinetic models in this study, the pseudo-second order successfully predicted the adsorption process.
Removal of the persistent pollutant chlorobenzene by adsorption onto activated montmorillonite
Applied Clay Science, 2009
The potential of activated bentonite was assessed for adsorption of chlorobenzene from aqueous solution. The bentonite used was treated by chemical and thermal activation over 100–500 °C. The thermal activation increased the adsorption capacity more strongly than chemical activation which consists to acid and hydrogen peroxide treatment. The removal is dominated by adsorption at low initial concentrations and low temperatures and favourable in acidic media. The dependence of the adsorption on pH appears to be related to the solubility of chlorobenzene. Thermodynamic parameters such as ΔH°, ΔS°, ΔG° and Ea have been calculated. The adsorption process is spontaneous and exothermic in nature. The Freundlich isotherm described the adsorption data over the concentration range (20–270 °C).