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1.
The natural cotton fiber was used to synthesize an anion exchange, containing ZrO2 film on its surface, NCFZC (natural cotton fiber/ZrO2 composite). This anion exchanger was produced by the reaction of the zirconium oxychloride and hydroxyl groups on surface of the natural cotton fiber. The material was used for Cr(VI) ions adsorption studies. Adsorption equilibrium time and optimum pH for Cr(VI) adsorption were found to be 6 h and 4.0, respectively. The Langmuir and Temkin isotherms were used to models adsorption equilibrium data. The adsorption capacity of NCFZC was found to be 1.33 mmol/g. Kinetic studies showed that the rate of adsorption of Cr(VI) on NCFZC obeyed a pseudo‐second‐order kinetic model.  相似文献   

2.
In the present work, biosorption of Cr(VI) by Nymphaea rubra was investigated in batch studies. Batch experiments were conducted to study the effect of initial sorbent dosage, solution pH and initial Cr(VI) concentration. The results showed that the equilibrium uptake capacity was increased with decrease in biomass dosage. The Cr(VI) removal was influenced by the initial chromium compound concentration. Langmuir and Freundlich adsorption isotherm models were used to represent the equilibrium data. The Freundlich isotherm model was fitted very well with the equilibrium data when compared to Langmuir isotherm model. The sorption results were analyzed for pseudo‐first order and pseudo‐second order kinetic model. It was observed that the kinetic data fitted very well with the pseudo‐second order rate equation when compared to the pseudo‐first order rate equation. Fourier transform infrared spectrum showed the presence of different functional groups in the biomass. The surface morphology of the sorbent was exemplified by SEM analysis. Aquatic weeds seem to be a promising biosorbent for the removal of chromium ions from water environment. This paper reports the research findings of a laboratory‐based study on the removal of Cr(VI) from the synthetic solution using the dried stem of N. rubra as a biosorbent.  相似文献   

3.
Nymphaea rubra stem was used as a low cost and easily available biosorbent for the removal of Reactive Red 2 dye from an aqueous solution. Initially, the effects of biosorbent dosage (0.2–1.0 g L–1), pH (1–6), and dye concentration (30–110 mg L–1) on dye removal were studied. Batch experiments were carried out for biosorption kinetics and isotherm studies. The results showed that dye uptake capacity was found to increase with a decrease in biosorbent dosage. Equilibrium uptake capacity was found to be greatest at a pH value of 2.0, when compared to all other pH values studied. The equilibrium biosorption isotherms were analyzed by the Freundlich and Langmuir models. The equilibrium data was found to fit very well with the Freundlich isotherm model when compared to the Langmuir isotherm model. The kinetic data was analyzed using pseudo-first order and pseudo-second order kinetic models. From the results, it was observed that the kinetic data was found to fit the pseudo-second order kinetic model very well. The surface morphology of the stem of the N. rubra biosorbent was exemplified by scanning electron microscopy. Fourier transform infrared analysis was employed to confirm the existence of an amine group in the stem of N. rubra.  相似文献   

4.
Ferric oxide‐loaded hybrid sorbents are environmentally benign and exhibit sorption behaviors for chromium removal from waters. In the current study, glycidyl methacrylate‐based polymer (GMD) and nanosized ferric oxide loaded glycidyl methacrylate‐based polymer (GMDFe) were prepared and assayed to examine the effect of ferric oxide loading on chromium sorption from aqueous solution for the first time from the equilibrium and kinetic points of view. The experimental equilibrium data, suitably fitted by the Langmuir and Freundlich isotherms, have shown that ferric oxide loaded hybrid sorbent exhibits higher adsorption capacity than glycidyl methacrylate‐based polymer (GMD). The Langmuir isotherm model was found to be the most suitable one for the Cr(VI) adsorption. The maximum adsorption capacities of GMD and GMDFe sorbents were determined at pH 4 as 109.54 and 157.52 mg/g, respectively. A series of column experiments was carried out to determine the breakthrough curves. The column was regenerated by eluting Cr(VI) using NaOH (10% w/v) solution after adsorption studies.  相似文献   

5.
The adsorption behavior of methyl orange (MO) from aqueous solution onto raw bentonite (RB) sample was investigated as a function of parameters such as pH, inorganic anion, contact time, and temperature. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms. Langmuir adsorption capacity was found to be 34.34 mg/g at pH 4.0. The pseudo‐first‐order, pseudo‐second‐order kinetic, and the intra‐particle diffusion models were used to describe the kinetic data. The values of the energy (Ea), enthalpy (ΔH≠), and entropy of activation (ΔS≠) were calculated as 38.62 kJ/mol, 36.04 kJ/mol, and ?150.05 J/mol K, respectively, at pH 4.0.  相似文献   

6.
This paper reports on an approach for separating vanillin and syringaldehyde (VSA) from oxygen delignification spent liquor using non‐polar macroporous resin. The effects of temperature and pH on the adsorption isotherms were studied. The adsorption capacity and adsorption equilibrium constant were obtained using the Langmuir adsorption model at pH<4.5, where the ionization of the VSA to ionic forms was negligible. The standard enthalpy change was calculated using the van't Hoff equation and clearly showed that the adsorption is an exothermic process. The effect of pH on the adsorption isotherm is well‐described by a modified Langmuir model and shows that the adsorption equilibrium constant decreases significantly with the increasing pH. The VSA adsorbed on macroporous resin was eluted by ethyl ether. The separated VSA contained 37.51% vanillin, 31.88% syringaldehyde. The recoveries of VSA were 96.2 and 94.7%, respectively.  相似文献   

7.
In the present study, activated carbons were prepared from sisal fiber (Agave sisalana sp.) and pomegranate peel (Punica granatum sp.) using phosphoric acid as the activating agent. Both sisal fiber activated carbon (SFAC) and pomegranate peel activated carbon (PPAC) were characterized using methylene blue number, iodine number, BET surface area, SEM, and FTIR. The BET surface area of the SFAC and PPAC were 885 and 686 m2/g, respectively. The adsorption studies using C.I. Reactive Orange 4 dye on the SFAC and PPAC were carried out. The effects of time, initial adsorbate concentration, pH, and temperature on the adsorption were studied. The isotherm studies were carried and it was found that the Langmuir and Freundlich isotherms fit well for the adsorption of RO 4 on SFAC, while adsorption of RO 4 on PPAC is better represented by the Langmuir and Temkin isotherms. Adsorption kinetics of adsorption was determined using pseudo first order, pseudo second order, Elovich and intraparticle diffusion models and it was found that the adsorption process follows pseudo second order model. Thermodynamics parameters such as changes in free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) were determined by using van't Hoff equation. The positive ΔH value indicates that RO 4 dye adsorption on SFAC and PPAC is endothermic in nature.  相似文献   

8.
The adsorption of nickel and copper in a bicomponent system using the nonliving biomass of the marine brown alga Laminaria japonica was investigated in batch systems as a function of initial solution pH, contact time and temperature. The adsorption of nickel and copper was strongly pH dependent. Kinetic studies pointed to a rapid uptake with an equilibrium time of about 30 min. The kinetic curves were successfully fitted by linear regression to pseudo first and pseudo‐second‐order equations. The equilibrium data was analyzed using several models, including the extended Langmuir equation, modified extended Langmuir model and combined extended Langmuir‐Freundlich model. The results suggested that the competitive adsorption of nickel and copper at all temperatures was best represented by the combined extended Langmuir‐Freundlich isotherm. The isotherms indicated competitive uptake, with copper being preferentially adsorbed followed by nickel with an increase in the amount of solute in solution. Thermodynamic analysis revealed that the simultaneous adsorption of nickel and copper ions could be considered to be a spontaneous, endothermic process, with increased randomness.  相似文献   

9.
The purpose of this work is the removal of basic dyes (Safranine T and Brilliant Green) from aqueous media by depolymerization products (DP) obtained from aminoglycolysis of waste poly(ethylene terephthalate) (PET). The surface morphology and physical properties of depolymerization product were also determined. Adsorption behaviors (adsorption capacities, adsorption kinetics and adsorption isotherms) of these samples were realized at room temperature. Then, the amounts of residual dye concentrations were measured using Visible Spectrophotometer at 530 and 618 nm for Safranine T (ST) and Brilliant Green (BG), respectively. All adsorption experiments were carried out for different depolymerization products (DP1, DP2, DP3, and DP4). Adsorption capacities of depolymerization products for both of dyes decrease with following order: DP2 > DP4 > DP1 > DP3. The maximum adsorption capacities for ST and BG onto DP2 sample were found to be 29 and 33 mg g?1, respectively. In addition, the adsorption kinetic results show that the pseudo‐second‐order kinetic model is more suitable than pseudo‐first‐order model for the adsorption of basic dyes onto DP samples. Adsorption data were evaluated using Langmuir and Freundlich adsorption isotherm models. The results revealed that the adsorption of basic dyes onto DP sample fit very well Langmuir isotherm model. In conclusion, the depolymerization products of post‐consumer PET bottles can be used as low cost adsorbent for the removal of basic dyes from wastewaters.  相似文献   

10.
This study concentrates on the possible application of the spent cottonseed husk substrate (SCHS), an agricultural waste used after the cultivation of white rot fungus Flammulina velutipes, to adsorb methylene blue (MB) from aqueous solutions. Batch studies were carried out with variable initial solution pH, adsorbent amount, reaction time, temperature, and initial MB concentration. MB uptake was favorable at pH ranging from 4.0 to 12.0, and the equilibrium adsorption capacity of 143.5 mg g?1 can be reached promptly within about 240 min. The combination analysis of FTIR and BET techniques revealed that the massive functional groups on the biosorbent surface, such as hydroxyl and carboxyl, were responsible for the biosorption of MB. It was found that adsorption data matched the pseudo‐second order kinetic and Langmuir isotherm models. Thermodynamic parameters of free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°), obtained from biosorption MB ranging from 293 to 313 K, showed that the sorption experiment was a spontaneous and endothermic process. The study highlighted a new pathway to develop a new potential utilization of SCHS as a low‐cost sorbent for the removal of MB pollutants from wastewater.  相似文献   

11.
The adsorption performance of β‐ionone on four types of granular activated carbon (GAC) in water was investigated through batch experiments. The effect of initial β‐ionone concentrations and natural organic matter (NOM) adsorbed on GAC, adsorption kinetic and isothermal models were also studied. The results showed that four types of GAC all had good adsorption performance for β‐ionone, the equilibrium adsorption amount of the GAC employed was in the order of YK > GK > MZ‐A > MZ‐B. The adsorption amount increased with increasing initial concentrations. The presence of NOM could reduce adsorption of β‐ionone to a certain extent, and small molecular weight (MW) fractions (particularly <1000 Da) exhibited a remarkably competitive effect on the adsorption of β‐ionone. The experimental data showed good correlation with pseudo‐first‐order model. Furthermore, adsorption of β‐ionone on GAC fitted Freundlich, Langmuir, and Tempkin isotherms in the range of experimental concentrations, but followed Freundlich isothermal model most appropriate. The thermodynamic parameters were calculated by the results of the experiment, which showed adsorption of β‐ionone on GAC as being endothermic and spontaneous.  相似文献   

12.
The present work involves the study of Se(IV) adsorption onto bagasse fly ash. The adsorbents were coated with a ferric chloride solution for the effective removal of selenium. The physico‐chemical characterization of the adsorbent was carried out using standard methods, e. g., proximate analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, thermo‐gravimetric analysis and differential thermal analysis. Batch experiments were carried out to determine the effect of various parameters such as adsorbent dose, initial pH, contact time, and temperature on the adsorption process. Results obtained from these studies were analyzed using various kinetic models and isotherms. Se(IV) adsorption onto adsorbent was high at low pH values, and decreased with an increase in initial pH. A temperature study showed that the uptake of Se(IV) was greatest at 293 K, within the temperature range studied. The parameters of pseudo first order, pseudo second order, and Weber‐Morris intra‐particle kinetic models were determined. Equilibrium isotherms were analyzed using Langmuir, Freundlich, and Temkin isotherms. Error analyses were also carried out using hybrid fractional error function and Marquardt's percent standard deviation.  相似文献   

13.
Batch sorption experiments were carried out for the adsorption of the basic dye Rhodamine B from aqueous solution using baryte as the adsorbent. The effect of adsorbent dosage, temperature, initial dye concentration and pH were studied. Adsorption data were modeled using first and second order kinetic equations and the intra particle diffusion model. Kinetic studies showed that the adsorption process followed second order rate kinetics with an average rate constant of 0.05458 g mg–1 min–1. Dye adsorption equilibrium was attained rapidly after 30 min of contact time. The equilibrium data was fitted to the Langmuir, Freundlich and Tempkin isotherms over a dye concentration range of 50–250 mg/L. The adsorption thermodynamic parameters showed that adsorption was an exothermic, spontaneous and less ordered arrangement process. The adsorbent, baryte, was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The results showed that baryte has good potential for the removal of Rhodamine B from dilute aqueous solution.  相似文献   

14.
The adsorption of fluoxetine onto activated carbons (ACs) prepared from almond tree pruning by steam and CO2 activation under different temperature conditions (650–950°C), was studied. In both series increasing the temperature caused an increase in the BET apparent surface area, yielding ACs with SBET up to 870 and 710 m2 g?1 after steam and CO2 activation, respectively. Also, a slight widening of the porosity was found in both cases. In order to modify the functionality of the ACs, two of them were impregnated with triethylenediamine (TEDA) prior to the adsorption process, which caused a decrease in the AC apparent surface mainly due to micropore blockage. The fluoxetine adsorption isotherms at 25°C showed maximum adsorption capacities between 110 and 224 mg g?1. The adsorption isotherms were analyzed using Langmuir and Freundlich models. Although the impregnation reduced the pore volume, it did not cause a decrease in the fluoxetine maximum adsorption capacity, but a modification in the adsorption mechanism was observed.  相似文献   

15.
The effect of varying parameters such as dye concentration, adsorbent dose, pH and temperature on the adsorption capacity of Pleurotus ostreatus is investigated. The commonly available white rot fungus Pleurotus ostreatus is investigated as a viable biomaterial for the biological treatment of synthetic basic methylene blue effluents. The results obtained from the batch experiments reveal the ability of the fungus to remove methylene blue. The performance is dependent on the dye concentration, pH, and fungal biomass. The equilibrium and kinetics of adsorption are investigated and the Langmuir equation is used to fit the equilibrium isotherm. The adsorption isotherm of methylene blue follows only the Langmuir model with a correlation coefficient of ca. 0.96–0.99. The maximum adsorption capacity is ca. 70 mg of dye per g of dry fungus at pH 11, 70 mg L–1 dye, and 0.1 g L–1 fungus concentration, respectively. This study demonstrates that the fungus could be used as an effective biosorbent for the treatment of dye‐containing wastewater streams.  相似文献   

16.
Magnetic hydroxyapatite (HAP), which combined superparamagnetic Fe3O4 nanoparticles and HAP, composite materials were prepared by ultrasound method in this paper. It has also been found that these materials have the ability to adsorb phenol in wastewater. The magnetic materials were investigated by scanning electron microscope, X‐ray diffraction (XRD), Fourier transform infrared spectroscopy, thermal gravimetric analysis, vibrating sample magnetometer, and N2 adsorption in order to elucidate the morphology, structure, and other properties. When the prepared magnetic materials were calcined at 200°C, the prepared Fe3O4 was oxidized to Fe2O3, possessing loose‐shaped holes with a high specific area of 325.2 m2/g, a magnetization intensity of 12.5 emu/g, and the N2 adsorption isotherm belongs to porous adsorption type I. Moreover, the magnetic HAP can adsorb 90% phenol in wastewater. This means that it is an excellent recyclable phenol sorbent for sewage treatment. Experiments confirmed that the Freundlich adsorption isotherms model applies to lower phenol concentrations (0–50 mg/L), while for high phenol concentrations (50–500 mg/L) the Langmuir adsorption isotherms model fits. The magnetic sorbents have the capacity to regenerate after reaching adsorption saturation using ethanol as eluant and external magnetic field as separation unit. The efficiency of adsorption was reduced only by 10% over a six time use period.  相似文献   

17.
The present study describes an electrocoagulation process for the removal of iron from drinking water using magnesium as the anode and galvanized iron as the cathode. Experiments were carried out as a function of pH, temperature and current density. The adsorption capacity was evaluated using both the Langmuir and the Freundlich isotherm models. The results show that the maximum removal efficiency of 98.4% was achieved at a current density of 0.06 A dm–2, at a pH of 6.0. The adsorption of iron was better explained by fitting the Langmuir adsorption isotherm, which suggests a monolayer coverage of adsorbed molecules. The adsorption process followed a second‐order kinetics model. Temperature studies showed that adsorption was endothermic and spontaneous in nature.  相似文献   

18.
Dodecylammonium bentonite (DB) and dodecylammonium sepiolite (DS) were used as sorbents for phenoxyalkanoic acid herbicides 2,4‐D ((2,4‐dichlorophenoxy)acetic acid), 2,4‐DP ((RS)‐2‐(2,4‐dichlorophenoxy)propionic acid), 2,4‐DB (4‐(2,4‐dichlorophenoxy)butyric acid), 2,4,5‐T ((2,4,5‐trichlorophenoxy)acetic acid), and MCPA ((4‐chloro‐2‐methylphenoxy)acetic acid). Langmuir, Freundlich, and the linear Henry’s Law isotherm adsorption parameters were calculated from the adsorption isotherms. Langmuir equation showed poor fit for both adsorbents. According to the evaluation using the Freundlich equation, the DS sample showed much higher and stronger sorption capacity than DB. Similar behaviour was also observed in the case of the linear Henry’s Law isotherm. The adsorption of the herbicides on both DB and DS decreased in the order of 2,4‐DB > 2,4,5‐T > 2,4‐DP > 2,4‐D > MCPA.  相似文献   

19.
A macroporous, hydrophobically modified poly(acrylic acid‐acrylamide) hydrogel was prepared. The fourier transform infrared (FTIR) spectrum and field emission scanning electron microscopy (FE‐SEM) results showed that the hydrogel had a macroporous structure. The dynamic swelling and removal of cationic dyes, crystal violet (CV) and basic magenta (BM), by this macroporous hydrophobically modified poly(acrylic acid‐acrylamide) hydrogel were studied. The adsorption capacity and kinetic and isotherm studies of the cationic dyes into the hydrogels have been evaluated. It was found that the macroporous hydrophobically modified hydrogel (M) exhibited improved swelling and adsorption capacity compared with the non‐macroporous hydrophobically modified hydrogel (NM). The adsorption process agreed very well with the Langmuir model and the adsorption of the cationic dyes depended on the pH of the solution via a mechanism combining swelling, electrostatic, and hydrophobic interactions. Moreover, adsorption kinetic studies showed that the adsorption followed a pseudo‐second‐order kinetic model, indicating that chemical adsorption was the rate‐limiting step.  相似文献   

20.
For the first time ever, Enteromorpha compressa macroalgae (ECM), which is commonly found in Turkey, has been used as biosorbent by us. This study aims to investigate the biosorption of Cd2+ from aqueous solutions in a batch system by using an alga of ECM in different concentrations, pH levels, agitation rates (90–150 rpm), and contact periods. The maximum biosorption capacity of the ECM was found to be 9.50 mg/g at pH 6, Cd2+ initial concentration of 10 mg/L and agitation rate 150 rpm. Cadmium removal efficiency was about 95%. The experimental isotherm data were analyzed using the Langmuir and Freundlich equations. Isotherm parameters for both equations were determined and discussed. The stated biosorption mechanism is explained by the Freundlich isotherm (r2 = 0.998) theory. Two simplified kinetic models including a pseudo‐first‐ and second‐order equation were selected to follow the biosorption process. Kinetic parameters; rate constants, equilibrium adsorption capacities and related correlation coefficients, for each kinetic model were calculated and discussed. It was shown that the biosorption of cadmium onto ECM could be described by the pseudo‐second‐order equation (r2 > 0.99).  相似文献   

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