The removal of phenolic compounds from aqueous solutions by organophilic bentonite (original) (raw)
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Journal of Colloid and Interface Science, 2004
The characterization of tetraethylammonium bentonite and the adsorption of p-chlorophenol (p-CP) onto organophilic bentonite (tetraethylammonium bentonite) was studied as a function of the solution concentration and temperature. The observed adsorption rates were found to fit first-order kinetics. The rate constants were calculated for temperatures ranging between 15.0 and 35.0 • C at constant concentration. The adsorption energy E and adsorption capacity q m for the phenolic compound adsorbing on organophilic bentonite were estimated using the Dubinin-Radushkevic equation. Thermodynamic parameters (g a , h a , s a) were calculated by a new approximation from the isotherms of p-CP adsorption on organophilic bentonite. These isotherms were modeled according to Freundlich and Dubinin-Radushkevic adsorption isotherms. The amount of adsorption of p-chlorophenol on organophilic bentonite was found to be dependent on the relative energies of adsorbent-adsorbate, adsorbate-solvent, and adsorbate-adsorbate interactions.
IntechOpen eBooks, 2024
Bentonite clay modified with cetyltrimethylammonium bromide (CTAB) has been investigated as an effective adsorbent for the removal of bisphenol A (BPA) and pentachlorophenol (PCP) from aqueous solutions. The adsorption performance of Bentonite-CTAB was evaluated by conducting batch adsorption experiments under different conditions. The adsorption isotherms of BPA and PCP on Bentonite-CTAB (BT-CTAB) were analyzed using the Langmuir and Freundlich models. The Langmuir model provided a better fit to the experimental data, suggesting the presence of monolayer adsorption. The adsorption kinetics of BPA and PCP on Bentonite-CTAB were studied using pseudo-first-order and pseudo-second-order models. The results indicate that the adsorption process follows pseudo-secondorder kinetics, suggesting that the adsorption is controlled principally by chemisorption. Equilibrium time for both pollutants was achieved within 30-40 min. The results of adsorption studies indicated that Bentonite-CTAB exhibited excellent adsorption capacity for bisphenol A and pentachlorophenol. The high surface area and presence of active sites on Bentonite-CTAB favored adsorption of pollutants from aqueous solution. The adsorption process adopted pseudo-second-order kinetics, indicating the involvement of chemisorption. the adsorption isotherms of BPA and PCP on Bentonite-CTAB were analyzed using the Langmuir and Freundlich models. The Langmuir model provided a better fit to the data, suggesting monolayer adsorption.
Phenol Red Adsorption from Aqueous Solution on the Modified Bentonite
Journal of Chemistry, 2020
In the present work, the modified bentonites were prepared by the modification of bentonite with cetyltrimethylammonium bromide (CTAB), both cetyltrimethylammonium bromide and hydroxy-Fe cations and both cetyltrimethylammonium bromide and hydroxy-Al cations. X-ray diffraction (XRD), thermal analysis (TG-DTA), infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and nitrogen adsorption/desorption isotherms were utilized to characterize the resultant modified bentonites. The modified bentonites were employed for the removal of phenol red dye from aqueous solution. Phenol red adsorption agreed well with the pseudo-second-order kinetic model. The equilibrium data were analyzed on the basis of various adsorption isotherm models, namely, Langmuir, Freundlich, and Dubinin‒Radushkevich models. The highest monolayer adsorption capacity of phenol red at 30°C derived from the Langmuir equation was 166.7 mg·g−1, 125.0 mg·g−1, and 100.0 mg·g−1 for CTAB‒bentonite, Al‒CTAB‒bentonite, ...
Adsorption of o-, m- and p-nitrophenols onto organically modified bentonites
Journal of Hazardous Materials, 2011
Experiments were conducted on the adsorption characteristics of o-, m-and p-nitrophenols by organically modified bentonites at different temperatures. Two organobentonites (HDTMA-B and PEG-B) were synthesized using hexadecyltrimethylammonium bromide (HDTMABr) and poly(ethylene glycol) butyl ether (PEG). Synthesized HDTMA-B and PEG-B were characterized by XRD, FTIR and DTA-TG analyses and their specific surface area, particle size and pore size distributions were determined. BET surface areas and basal spacings (d 0 0 1) of the HDTMA-B and PEG-B were found to be 38.71 m 2 g −1 , 69.04 m 2 g −1 and 21.96Å, 15.17Å, respectively. Increased adsorption with temperature indicates that the process is endothermic for o-nitrophenol. On the other hand m-and p-nitrophenols exhibited lower rates of adsorption at higher temperatures suggesting a regular exothermic process taking place. Results were analyzed according to the Langmuir, Freundlich and Dubinin-Redushkevich (D-R) isotherm equations using linearized correlation coefficient at different temperatures. R L separation factors for Langmuir and the n values for Freundlich isotherms showed that m-and p-nitrophenols are favorably adsorbed by HDTMA-B and, p-nitrophenol is favored by PEG-B. Adsorption of o-, m-and p-nitrophenols as single components or from their binary mixtures on HDTMA-B and, p-nitrophenol on PEG-B are all defined to be physical in nature.
Journal of Hazardous Materials, 2005
In this work, it is intended to study the effect of adsorbent concentration on the adsorption of phenol by hexadecyl trimethyl ammoniumbentonite. The experiments were conducted in two groups. The adsorption of hexadecyl trimethyl ammonium bromide (HDTMA) on bentonite was studied in the first group of experiments. It was observed that the all HDTMA was adsorbed by the bentonite, even when the amount used exceeded 100% of cation exchange capacity (CEC). After the modification of bentonite by using HDTMA in an amount equivalent to 100% of CEC, the adsorption experiments were performed at five different adsorbent concentrations ranging from 2 to 10 g/L. A type V isotherm and a non-linear increase in percent removal with adsorbent concentration were observed. The observation of the non-linear relation between the percent removal and adsorbent concentration was attributed to the effect of intra particle interactions and it was represented by a second order polynomial. Several adsorption isotherm equations were applied to the experimental data. Although, the Freundlich equation fitted fairly well, it failed to represent the plateau and the second region that appeared in the isotherm. Therefore, an equation giving the equilibrium concentration as a function of initial and adsorbent concentrations was suggested.
Adsorption of phenol from aqueous solutions by organomontmorillonite
Desalination, 2011
Adsorption of phenol from aqueous solution onto the Na-bentonite was investigated in a batch system. Equilibrium, thermodynamics and kinetic studies were conducted by considering the effects of pH, initial phenol concentration, contact time, and temperature. The results showed that the uptake of the phenol increased with an increase in initial phenol concentration. The pH for optimum adsorption was 3 for the phenol (Q = 8.76 mg/g). Langmuir isotherm described the adsorption of phenol onto the Na-bentonite (R 2 = 0.93) is better than the Freundlich model (R 2 = 0.77). Adsorption kinetics data obtained for the phenol sorption were fitted using pseudo-first-order and pseudosecond-order. It was found that the kinetics data fitted well into the pseudo-second-order kinetics. Thermodynamic parameters such as Gibbs free energy (ΔG 0), standard enthalpy (ΔH 0) and standard entropy (ΔS 0) were evaluated. The result showed that adsorption of the phenol onto Na-bentonite was spontaneous and endothermic in nature. The results indicate that there is significant potential for Nabentonite as an adsorbent material for phenol removal from aqueous solutions.
Study of the Paranitrophenol Adsorption on the Commercial Bentonite
Journal of environment and earth science, 2014
This work focuses on the study of the behavior of commercial yellow bentonite (BTJ) vis-a-vis paranitrophenol (PNP). Before beginning the study of adsorption, we realized the physiquo-chemical characterization of clay by FTIR, BET and XRD technical. The surface area of the bentonite is calculated by BET 35 m 2 /g. The adsorption of para-nitrophenol is carried out at room temperature and at a controlled pH. The kinetic study showed that the equilibrium time is 5h. The kinetic model was a pseudo second order. Adsorption isotherm was the Langmuir model. The adsorption capacity was about 0.37 mg / g. Keywords: Yelow bentonite, paranitorphenol, adsorption, optimisation.
Brazilian Journal of Development
Biphenyl, a frequently encountered and resilient compound in wastewater, proves resistant to conventional treatment methods because of its enduring nature. It forms the structural basis for persistent organic pollutants such as PCBs. In this study, we explored the adsorption of biphenyl in an organo-aqueous medium using both natural (Bent) and organomodified (CTAB-Bent) bentonite clay. Our objective was to highlight its potential for biphenyl wastewater treatment. We analyzed the physicochemical and textural properties of these clays through FTIR, XRF, XRD, SEM, BET method, and Zeta potential measurements. Impressively, these materials exhibited remarkable biphenyl adsorption capacity under acidic conditions, with Bent achieving 60% removal and CTAB-Bent an impressive 91%. We investigated the adsorption kinetics using first-order and pseudo-second-order models and assessed isotherm data with the Langmuir, Freundlich, and Langmuir-Freundlich (sips) equations. The Langmuir model, at p...
Removal of phenol by adsorption
Phenolic compounds are some of the major hazardous compounds in industrial wastewater due to their poor biodegradability, high toxicity and ecological aspects. These compounds are listed by US Environmental Protection Agency (EPA) among the priority pollutants for instance phenols are released into water from industrial effluent discharges such as petroleum refinery wastewater. Classical methods employed for phenol removal are either costly or limited to large-scale applications such as biological and thermal decomposition methods. In this study an Egyptian Bentonite clay has been used for the adsorption of phenol from aqueous solutions over a concentration range of 10-100 mg/l, shaking time of 5-120 min, stirring rate from 50-250 r.p.m and adsorbent dosage from 0.1to 0.5 g. The Experiments were carried out for the analysis of adsorption equilibrium capacities using a batch equilibrium technique. The process of uptake follows both the Langmuir and Freundlich isotherm models. The complete removal of phenol was observed with initial concentration of 10 mg/l and 0.5 g of bentonite, speed rate of 200 r.p.m. with 30 min time of contact. All Experiments were done at room temperature. 588 3. The increase of the initial concentration of phenol leads to the increase of the residual concentration and decrease of the percentage removal. 4. The experimental data for phenol is well fitted to both the linearized Langmuir isotherm and the linearized Freundlich isotherm.
JOURNAL OF ADVANCES IN CHEMISTRY, 2012
The efficiencies of Hexadecyltrimethylammonium bromide (HDTMABr) modified bentonite (HDTMABt) for phenol and chromium removal from aqueous solutions were studied in batch experiments at pH = 9 and pH = 2 values, respectively. FTIR, SEM, XRD and BET analyses indicated that the HDTMABr molecules were intercalated in the interlayer and at the external surface of initially Na-bentonite (NaBt). Adsorption experiments showed that the HDTMABt was more efficient than the initial NaBt for the removal of phenol and chromium, simultaneously, the extent of the enhancement differed among these pollutants depending on their affinity towards these samples. The kinetic study revealed a rapid adsorption onto HDTMABt of the pollutants during the initial stage (teq < 1h). The pseudo-second-order equation fitted well to the experimental data. Phenol adsorption on NaBt and HDTMABt could be described by a linear Freundlich equation while Langmuir and Freundlich models were the most suitable for Cr(VI)...