Investigation on Adsorption Behavior of Some Pollutant Aromatic Amines onto Bentonite by Spectrofluorometric Method (original) (raw)
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Adsorption, 2013
Polycyclic aromatic hydrocarbons (PAHs) have widely been studied and a special concern because of their mutagenic and carcinogenic activities. In this study, natural-and chemically modified-bentonite were characterized by means of N 2 adsorption method, XRD, SEM, FT-IR, elemental and thermal analysis and zeta potential techniques and their adsorption behavior were then investigated toward naphthalene, which is the first member of the PAHs. The effects of various experimental parameters such as pH, contact time and temperature on adsorption were tested in the experiments. The optimum pH values for naphthalene adsorption onto natural bentonite (NB) and hexadecyltrimethylammonium bromide modified bentonite (HB) were found to be as 4.00 and 5.97, respectively. The equilibrium contact time was 60 min for both of the adsorbent. A comparison of the linear and nonlinear method of three widely used kinetic models, which are Lagergren-first order, the pseudo-second-order and Elovich kinetics, and the most popular isotherms, which are Langmuir and Freundlich, were examined to the experimental data of the adsorption of naphthalene onto NB and HB. The kinetic results indicated that the pseudo-secondorder kinetic model with high correlation coefficients was more suitable than the other kinetic models e.g. Lagergren first-order and Elovich. All results showed that the modified bentonite can be used as an adsorbent to remove PAHs from aqueous solutions by using adsorption method due to its effectiveness, simplicity and low-cost than the other conventional methods.
Adsorption of sodium dodecylbenzene sulfonate on organophilic bentonites
2001
A bentonite from the Cauca Valley in Colombia was treated with tetramethylammonium bromide TAB , hexade-Ž. Ž. cyltrimethylammonium bromide CTAB , hexadecylbenzyldimethylammonium chloride CDAC , and alkylbenzyldimeth-Ž. ylammonium chloride BTC , in order to obtain organophilic compounds. The treatment was carried out at 50% and 100% Ž. Ž. of the cationic exchange capacity CEC of the natural bentonite NB. The adsorption of an aqueous solution of sodium Ž. dodecylbenzene sulfonate DBS over the natural and modified bentonites was studied. The experimental data points were fitted to several equations applicable to adsorption in solution such as: Langmuir, BET and Freundlich. The Langmuir isotherm adequately describes the adsorption process in all cases. The adsorption grade can be quantified by the distribution coefficient, for low concentrations in solution expressed in molality, K. The affinity of organophilic bentonites by DBS dm can be expressed in terms of the standard adsorption Gibbs energy. The class and structure of the hydrocarbon chains of the quaternary ammonium ions adsorbed over the bentonite determine the DBS adsorption grade.
Adsorption of aniline, N-methyl aniline and N, Ndimethyl aniline from aqueous solution was investigated using raw and modified Jordanian bentonite. The modification was done using hexadecyltrimethylammomium chloride (HDTMA-Cl), C 19 H 42 N Cl. The raw and the modified bentonite (organobentonite) were characterized using X-Ray fluorescence spectroscopy (XRF), X-Ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), UV/VIS spectroscopy and cation exchange capacity (CEC) methods. The adsorption studies were performed in batch system, and the effect of various experimental parameters such as solution PH, initial concentration of pollutants were evaluated upon the aniline and its derivatives adsorption onto raw and organobentonite. It is found that removal of aniline from aqueous solution using raw bentonite ranges from 29.5% to 40.6% while for organobentonite ranges from 60.2% to 88.0%, for N-methylaniline from 19.0% increased to 69.5% and for N,N-dimethyaniline the adsorption increase from 19.4% to 96.4%. Maximum achievement was found to be in the range PH 3.1 to 4.2 for the organobentonite samples. The parameters indicated that organobentonite was feasible and has a significant potential as an adsorbent for removal of aniline and its derivatives from aqueous solutions.
The Use of Modified Bentonite for Removal of Aromatic Organics from Contaminated Soil* 1
Journal of colloid and interface …, 1997
and Reliability Act (CERCLA). The aromatic fraction of This study investigates the clay-aromatic interactions with a gasoline's hazardous constituents includes benzene, toluene, view to the use of bentonite clay for binding benzene, toluene, ethylbenzene, and xylene (commonly called the BTEX comethylbenzene, and o-xylene (BTEX compounds) in contaminated pounds). soils. BTEX compounds are the most toxic aromatic constituents Today, several options such as chemical degradation, soil of gasoline present in many underground storage tanks. Modified flushing, thermal treatment, soil vapor extraction, and bio-(organophilic) and ordinary bentonites are used to remove these degradation are available to treat aromatic wastes and the organics. The organophilic bentonites are prepared by replacing matrices they contaminate, particularly soils (3). The applithe exchangeable inorganic cations present in bentonite particles cation of these techniques entails high costs. In addition, the with a quaternary ammonium salt. Various clay-to-soil ratios were applied to determine the efficiency of the modified bentonite in present methods of disposing of these wastes (i.e., placement enhancing the cement-based solidification/stabilization (S/S) of in drums for burial, pooling for evaporation, and storage in BTEX contaminated soils. Toxicity characteristics leaching procelined disposal sites) are not reliable and do not provide a dure (TCLP) tests were performed on soil samples to evaluate the permanent solution for containment. It is essential that a leaching of the organics. In addition, X-ray diffraction analyses safe and cost-effective cleanup process be developed as an were conducted to assess the changes in the basal spacing of the alternative to the current treatment and disposal practices. clays as a result of their interaction with BTEX compounds. The One such treatment process could be developed using findings of this study reveal that organophilic bentonite can act modified (organophilic) clays to adsorb aromatic comas a successful adsorbent for removing the aromatic organics from pounds from contaminated soils and prevent them from polcontaminated soil. Thus, this material is viable for enhancing the luting the groundwater. Research conducted (4-6) on the performance of cement-based S/S processes, as an adsorbent for adsorption of organics by clays indicates that quaternary petroleum spills, and for landfill liners and slurry walls. ᭧ 1997 Academic Press ammonium cations such as hexadecyltrimethylammonium Key Words: bentonite; aromatic compounds (BTEX); organo-(HDTMA) interact with clays and replace the exchangeable philic clay; cement-based solidification/stabilization (S/S) proinorganic cations on their surfaces, forming a stationary cess; basal spacing; XRD analysis. phase in the clay particles. In addition, as a result of the larger size of the HDTMA cations compared with that of the replaced cations, the interlamellar distance (basal spac-191
Adsorption of Some Organic Compounds by Hexadecyltrimethylammonium - Bentonite
Reviews in Chemical Engineering, 2000
In this study, the removal of organic contaminants from wastewater has been studied by using hexadecyltrimethylammonium bentonite (HDTMAbentonite). HDTMA-bentonite was synthesized by placing quaternary ammonium surfactant (hexadecyltrimethylammonium bromide) on the sodium bentonite (Na-B) by cation exchange. The sorption of organic pollutants was examined by batch equilibration method at 25°C. As organic contaminants polar compounds (methylene blue, benzoic acid and salicylic acid) and nonpolar compounds (toluene and xylene) were used. The concentrations of the organic pollutants used ranged from 0 to 700 mg/L. Methylene blue, benzoic acid and salicylic acid sorptions to HDTMA-bentonite were characterized by relatively strong solute uptake. Toluene and xylene sorptions to HDTMA-bentonite were weaker.
Odor-active Compound Adsorption onto Bentonite in
2013
This work extends the concepts proposed in a previous research paper about the interaction between the aroma of two white wines and bentonites. Such previous results led to hypothesized that some odor-active compounds were removed through direct adsorption mechanism on the clays. As a consequence, this paper examined the adsorption isotherms at 17±1°C of three bentonite samples added in three different amounts to a model white wine without the presence of wine macromolecule. The clays were analyzed for the elemental composition, the surface charge density, and the specific surface area (SSA) and differences were analyzed by Tukey's test. The analysis of variance (ANOVA) was used to demonstrate the significance of the bentonite on the aroma reduction. The Langmuir and the Freundlich models were fitted to the adsorption data. The most experimental adsorption isotherms were robustly fitted by the Freundlich equation indicating that, under the condition of the study, the adsorption process more frequently occurred with a heterogeneous energy distribution of an infinite number of surface active sites. Overall, the modeling prediction ability tested by the error on r 2 in cross validation enhanced differences both among the odor-active compounds and among the clays. Samples having a lower SSA value and a greater charge density per surface unit seemed to interact with most of the odor-active compounds primarily through physical mechanisms. Differently, the clay with a large SSA value and a low charge density per surface unit promoted stronger adsorptions that were probably driven by chemical interactions especially for ethyl esters. For the tested odor-active compounds differences in the adsorption intensity and capacity depended mainly on the bentonite characteristics rather than on the properties of the substances.
Scientific Reports
Herein, the facile one step acid activation of bentonite derived functionalized adsorbent (AB) for the effective remediation of both ionic and non-ionic secondary pesticides, ametryn and metolachlor has been attempted. The surface characteristics of AB were examined by the nitrogen adsorption–desorption analysis, scanning electron microscopy (SEM), and Fourier Transforms Infrared (FTIR) Spectroscopy. The adsorptive behavior was evaluated with respect to the effect of contact time, initial concentrations and solution pH. The equilibrium data were fitted to the Langmuir, Freundlich and Temkin isotherm models, while the adsorption kinetic was analyzed using the pseudo-first order and pseudo-second order kinetic equations. Thermodynamic parameters including the standard enthalpy change (ΔH°), standard entropy change (ΔS°), and Gibbs free energy change (ΔG°) were established. Thermodynamic analysis illustrated that the adsorption process was feasible and exothermic in nature, while the c...
Equilibrium and kinetic adsorption of drugs on bentonite: Presence of surface active agents effect
Applied Clay Science, 2014
The adsorption of five drugs: promethazine (PM), triflupromazine (TFP), trimethoprim (TM), carbamazepine (CM), and ibuprofen (IBU) onto bentonite (Bent) was studied spectrophotometrically in aqueous solutions and in the presence of different type of surfactants i.e. anionic sodium dodecyl sulfate (SDS) and cationic dodecyl trimethyl ammonium bromide (DTAB). The adsorption experiments were carried out as a function of time, initial concentration and temperature. Adsorption kinetic data were modeled using the Lagergren first order and the pseudo-second order kinetic equations. Interlayer diffusion graphics were also plotted. The data obtained from all kinetic studies are fitted to the pseudo-second order kinetic equation better than the Lagergren first order kinetic equation, except the adsorption of IBU onto Bent. The Giles isotherms were used to understand the adsorption mechanism of drugs. Isotherms plotted appear to fit L-type according to Giles isotherm classification. The Langmuir and Freundlich isotherms were used to model the equilibrium data obtained. The Langmuir model appears to fit the isotherm data better than the Freundlich model. The adsorption capacity values found for the adsorption of drugs in aqueous solutions followed the order: PM N TFP N TM N CM N IBU. It was observed that the presence of surfactants had significant effects on the adsorption capacities, although it did not affect the equilibrium time of the adsorption processes.
Experimental Study Of Adsorption Properties Of Acid And Thermal Treated Bentonite From Tehran (Iran)
2013
The Iranian bentonite was first characterized by Scanning Electron Microscopy (SEM), Inductively Coupled Plasma mass spectrometry (ICP-MS), X-ray fluorescence (XRF), X-ray Diffraction (XRD) and BET. The bentonite was then treated thermally between 150°C-250°C at 15min, 45min and 90min and also was activated chemically with different concentration of sulphuric acid (3N, 5N and 10N). Although the results of thermal activated-bentonite didn-t show any considerable changes in specific surface area and Cation Exchange Capacity (CEC), but the results of chemical treated bentonite demonstrated that such properties have been improved by acid activation process.