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1.
《分离科学与技术》2012,47(3):501-513
Abstract

Activated carbons offer an efficient option for the removal of organic and inorganic contaminants from water. However, due to its high costs and difficulty in the regeneration, other low cost adsorbents have been used. In this work, the adsorption capacity of an adsorbent carbon with high iron oxides concentration was compared with that of a commercial activated carbon in the removal of a leather dye from an aqueous solution. The adsorbents were characterized using SEM/EDAX analysis and BET surface area. The capacity of adsorption of the adsorbents was evaluated through the static method at 25°C. The results showed that the color removal was due to the adsorption and precipitation of the dye on the surface of the solids. The adsorption equilibrium was described according to the linear model for the adsorbent carbon and the equilibrium constant was 0.02 L g?1. The equilibrium of adsorption on activated carbon exhibited a behavior typical of the Langmuir isotherm and the monolayer coverage was 24.33 mg g?1. A mathematical model was proposed to describe the dynamics of the color removal using a fixed bed considering that the color removal is due to the adsorption and the precipitation of the dye on the adsorbent.  相似文献   

2.
《分离科学与技术》2012,47(5):742-752
The efficacy of activated carbon prepared from Palm Kernel Shell (PKSAC) from agriculture biomass and coated with magnetic nanoparticle (Fe3O4) in the removal of Rhodamine B dye was investigated. Adsorption experiments were carried out at various initial pH, adsorbent dosage, initial dye concentration, particle size, and temperature. Kinetic analyses were conducted using pseudo first order, pseudo second order and intra particle diffusion models. However, the regression results showed that the adsorption kinetics was represented more accurately by the pseudo second order model. The pseudo second order kinetic constant obtained was 1.7 × 10?4 min?1 at 323 K when 200 mg L?1 dye concentration was used. The equilibrium data were well described by both Langmuir and Freundlich isotherm models. The Langmuir adsorption capacity was 625 mgg?1. The rate of adsorption improved with increasing temperature and the process was endothermic with ΔH value assessed at 80 kJmol?1. Results obtained reveal that activated carbon prepared from Palm Kernel Shell coated with magnetic nanoparticle from agriculture biomass can be an attractive option for dye removal from industrial effluent.  相似文献   

3.
《分离科学与技术》2012,47(6):903-912
The adsorption of malachite green (MG) dye using coconut shell based activated carbon (CSAC) was investigated. Operational factors such as the effect of pH, initial dye concentration, adsorbent dosage, contact time, and solution temperature on the adsorption process were studied. Solution pH strongly affected the chemistry of both the dye molecule and CSAC in solution. Optimum dye removal was obtained at pH ≥ 8.0. Equilibrium was reached in 120 minutes contact time. The Langmuir, Freundlich, and Dubinin–Radushkevich (D-R) isotherm models were used to evaluate the adsorption data. The adsorption data fitted the Langmuir model most with maximum adsorption monolayer coverage of 214.63 mg/g. Pseudo-first-order, pseudo second-order, and intraparticle diffusion models were also used to fit the experimental data. Kinetic parameters, rate constants, equilibrium sorption capacities, and related correlation coefficients, for each model were calculated and discussed. Thermodynamic parameters such as ΔG0, ΔH0, and ΔS0 were evaluated and it was found that the sorption process was feasible, spontaneous, and exothermic in nature. The mean free energy obtained from D-R isotherm suggests that the adsorption process follows physiosorption mechanism. The results showed that coconut shells could be employed as a low-cost precursor in activated carbon preparation for the removal of MG dye from wastewaters.  相似文献   

4.
《分离科学与技术》2012,47(9):2132-2145
Abstract

MgAl2O4 nanopowder has been prepared by alkoxides hydrolysis with further calcination at temperature of 700°C. The adsorption of a leather dye, Direct Black 38, onto this material was investigated. The sample was characterized by X-ray-diffraction (XRD), N2 adsorption–desorption isotherm and Fourier transform infrared spectroscopy. The results showed that sample present a pure phase, and the average nanocrystal size of 8 nm, the BET surface area is about 206.5 m2 · g?1 and total pore volume is about 1.44 cm3 · g?1. Adsorption kinetics data were modeled by film and pore diffusion model. The experimental isotherm was described by the Langmuir model. MgAl2O4 nanopowder presented a great removal efficiency of leather dye by adsorption process, with a maximum adsorption capacity of 833 mg of dye per gram of adsorbent.  相似文献   

5.
The ZnO/ZnMn2O4 nanocomposite (ZnMn) was used as adsorbent for the removal of cationic dye Basic Yellow 28 (BY28) from aqueous solutions. The adsorbent was characterized by X-ray diffraction, scanning electron microscope, TEM, Fourier transform infrared ray, BET, particle size distribution and zeta potential measurements. The adsorption parameters, such as temperature, pH and initial dye concentration, were studied. Kinetic adsorption data were analyzed using the pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models. The Langmuir and Freundlich isotherm models were applied to fit the equilibrium data. The maximum adsorption capacity of BY28 was 48.8 mg g?1. Various thermodynamic parameters, such as ΔG°, ΔH° and ΔS°, were calculated.  相似文献   

6.
Recently, the treatment of effluent by agricultural waste biomass has significantly attracted wide interest among researchers due to its availability, efficacy, and low cost. The removal of toxic Remazol Brilliant Blue-R (RBBR) from aqueous solutions using HNO3-treated Juglans nigra (walnut) shell biomass carbon as an adsorbent has been examined under various experimental conditions, such as initial pH, adsorbate concentration, adsorbent dosage, particle size, agitation speed, and type of electrolyte. The experiments are designed to achieve the maximum dye removal efficiency using the response surface methodology (RSM). The optimum pH, adsorbent dosage, and particle size were found to be 1.5, 7 g L−1, and 64 μm, respectively for maximum decolorization efficiency (98.24%). The prepared adsorbent was characterized by particle size, Brunauer–Emmett–Teller (BET) surface area, pore volume, zero-point charge (pHzpc), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy/energy dispersive X-ray spectroscopy (FE-SEM/EDX), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Based on fitting the experimental data with various models, the isotherm and kinetic mechanism are found to be more appropriate with Langmuir isotherm and pseudo-second-order kinetics. The adsorption mechanism can be described by the intra-particle diffusion model, Bangham, and Boyd plots. The overall rate of adsorption is controlled by the external film diffusion of dye molecules. The maximum monolayer adsorption capacity, (qmax) 54.38 mg g−1 for RBBR dye, was obtained at a temperature of 301 K. From a thermodynamic standpoint, the process is endothermic, spontaneous, and the chemisorption process is favored at high temperatures. Desorption studies were conducted with various desorbing reagents in various runs and the maximum desorption efficiency (61.78% in the third run) was obtained using the solvent methanol. Reusability studies demonstrated that the prepared adsorbent was effective for up to three runs of operation. The investigation outcomes concluded that walnut shell biomass activated carbon (WSBAC) is a cost-effective, eco-friendly, and bio-sustainable material that can be used for synthetic dye decolorization in aqueous media.  相似文献   

7.
Adsorption characteristics of four different dyes Safranin O (cationic), Neutral Red (neutral), Congo Red (anionic) and Reactive Red 2 (anionic) on Si-MCM-41 material having very high surface area are reported. The surface morphology of Si-MCM-41 material before and after adsorbing dye molecules are characterised by FTIR, HRXRD, nitrogen adsorption–desorption isotherms, FESEM, and HRTEM. The adsorption capacities of Si-MCM-41 for the dyes followed a decreasing order of NR > SF > CR > RR2. The adsorption kinetics, isotherm and thermodynamic parameters are investigated in detail for these dyes using calcined Si-MCM-41. The kinetics and isotherm data showed that both SF and NR adsorb more rapidly than CR and RR2, in accordance with pseudo-second-order kinetics model as well as intraparticle diffusion kinetics model and Langmuir adsorption isotherm model respectively. The thermodynamic data suggest that the dye uptake process is spontaneous. The high adsorption capacities of dyes on Si-MCM-41 (qm = 275.5 mg g?1 for SF, qm = 288.2 mg g?1 for NR) is explained on the basis of electrostatic interactions as well as H-bonding interactions between adsorbent and adsorbate molecules. Good regeneration capacity is another important aspect of the material that makes it potent for the uptake of dyes from aqueous solution.  相似文献   

8.
The present study explains the preparation and application of sulfuric acid–treated orange peel (STOP) as a new low-cost adsorbent in the removal of methylene blue (MB) dye from its aqueous solution. The effects of temperature on the operating parameters such as solution pH, adsorbent dose, initial MB dye concentration, and contact time were investigated for the removal of MB dye using STOP. The maximum adsorption of MB dye onto STOP took place in the following experimental conditions: pH of 8.0, adsorbent dose of 0.4 g, contact time of 45 min, and temperature of 30°C. The adsorption equilibrium data were tested by applying both the Langmuir and Freundlich isotherm models. It is observed that the Freundlich isotherm model fitted better than the Langmuir isotherm model, indicating multilayer adsorption, at all studied temperatures. The adsorption kinetic results showed that the pseudo-second-order model was more suitable to explain the adsorption of MB dye onto STOP. The adsorption mechanism results showed that the adsorption process was controlled by both the internal and external diffusion of MB dye molecules. The values of free energy change (ΔG o) and enthalpy change (ΔH o) indicated the spontaneous, feasible, and exothermic nature of the adsorption process. The maximum monolayer adsorption capacity of STOP was also compared with other low-cost adsorbents, and it was found that STOP was a better adsorbent for MB dye removal.  相似文献   

9.
《分离科学与技术》2012,47(1):94-104
In this work, calcined and uncalcined mixed clays containing kaolin, ball clay, feldspar, pyrophyllite, and quartz are examined as a potential adsorbent for the removal of crystal violet dye from aqueous solution. These clays are characterized by nitrogen adsorption/desorption isotherms, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and thermo gravimetric analysis (TGA). The kinetics and thermodynamic parameters as well as the effects of the pH, the temperature, and the adsorbent dosage have also been investigated. The experimental results indicate that the Langmuir model expresses the adsorption isotherm better than the Freundlich model. The obtained result showed a tremendous increase in the crystal violet adsorption capacity (1.9 × 10?3 mol g?1) after calcination, which is one order greater than that of the uncalcined mixed clay. The mechanism of the adsorption process is elucidated on the basis of experimental data. The percentage removal of crystal violet dye increases with increasing the pH, the temperature, and the adsorbent dosage. The investigation of kinetic studies indicates that the adsorption of crystal violet on calcined and uncalcined mixed clays could be described by the pseudo-second-order model. The negative Δ G 0 values obtained from the thermodynamic investigation confirm that the adsorption is spontaneous in nature. The adsorption results suggest that the calcined and uncalcined mixed clays can also be used as low cost alternatives to the expensive activated carbon for the removal of dyes from aqueous solution.  相似文献   

10.
Rare earth elements are an important strategic resource. However, a trace of Fe(III) impurity has serious adverse impact on the performance of rare earth materials. We synthesized a novel nitrogen-containing carbon material, ACLR-400, using lotus root as raw materials. The ACLR-400 was characterized by surface area analyzer, elemental analysis and FT-IR. The selectivity and removal efficiency of ACLR-400 towards Fe(III) were also investigated. The BET specific surface area of ACLR-400 was 68.44 m2·g?1, and the average pore diameter was 12.54 nm. With abundant nitrogen- containing functional groups and well-developed internal pore structure, ACLR-400 possesses strong adsorption affinity, excellent selectivity and removal efficiency for Fe(III). The adsorption capacity of ACLR-400 towards Fe(III) could reach to 0.46 mmol·g?1, selectivity coefficient with respect to La(III) was 8.9, and removal efficiency was 99.61%. The adsorption isotherm data greatly obey the Freundlich isotherm. In addition, ACLR-400 can be regenerated easily and possesses better regeneration ability and reusability.  相似文献   

11.
《分离科学与技术》2012,47(16):3657-3680
Abstract

The sorption and desorption of Eu (III) on H‐APC activated carbon using a batch technique has been studied as a function of carbon type, shaking time, initial pH solution, temperature, particle size of carbon, and concentration of the adsorbent and the adsorbate. The influence of different anions and cations on adsorption has been examined. The experimental data have been analyzed by Langmuir, Freundlich, and Temkin sorption isotherm models and the adsorption data for Eu (III) onto activated carbon were better correlated to the Temkin isotherm and the maximum absorption capacities obtained was 46.5 mg g?1. Anions of phosphate, carbonate, oxalate, and acetate were found to increase the adsorption of Eu (III), whereas nitrate, chloride and all studied cations, potassium, sodium, calcium, magnesium, and aluminum have a negative effect on the adsorption capacity. More than 99% europium adsorbed on H‐APC eluted with 0.5 M HCl solution. The activated carbon prepared from apricot stone using 70% H3PO4 could be considered as an adsorbent that has a commercial potential for Eu (III) treatment.  相似文献   

12.
The present study reports the preparation of an activated carbon produced from buriti shells (ACb) using ZnCl2 as activating agent and its ability to remove methylene blue dye (MB) from aqueous solutions. The obtained ACb was characterized by N2 adsorption–desorption isotherms, SEM and FT-IR. The results show that ACb presents microporous features with BET surface area (SBET) of 843 m2 g−1 and functional groups common in carbonaceous materials. Adsorption studies were carried out and experimental data were fitted to three isotherm models (Langmuir, Freundlich, and Redlich–Peterson) and four kinetic models (pseudo-first order, pseudo-second order, Elovich, and intraparticle diffusion). The isotherm model which best fitted to experimental data was Redlich–Peterson. However, the g parameter of this model indicated that the adsorption of MB onto ACb occurs according to the mechanism proposed by Langmuir, which showed maximum monolayer adsorption capacity of 274.62 mg g−1. Kinetic studies demonstrated that the Elovich model is suitable to describe the experimental data. Moreover, it was found that the intraparticle diffusion is the limiting step of adsorption process.  相似文献   

13.
《分离科学与技术》2012,47(4):533-544
This work addresses the preparation and characterization of inexpensive adsorbents for the removal of Ni (II) from aqueous solutions. Activated carbon based adsorbents have been prepared from plant based biomass resources, namely Pineapple stem ( Ananas Comosus ) and Bamboo Stem ( Bambuseae ). Adopting phosphoric acid and heat treatment techniques, it has been observed that the bamboo stem activated charcoal (BSAC) and pineapple stem (PS) adsorbents had a BET surface area of 116 and 11.47 m 2 /g, respectively. FTIR analysis indicated that various surface functional groups (such as C ≡ N stretching, stretching vibration of C = O, –CH3 wagging and C–O stretching vibration) contribute towards Ni (II) adsorption. Batch mode adsorption experiments were conducted for these adsorbents in the range of 50–300 mg/L Ni (II) solution concentration, 2–10 pH, 15–300 min. contact time, and 0.02–0.1 g/50 mL dosage. The BSAC adsorbent has been characterized with a metal uptake and %removal of 121.72 mg/g and 92.47, respectively, which corresponds to 45% higher metal uptake than corresponding bamboo based adsorbents presented in the literature. Further experimentation with BSAC enabled to achieve activated charcoal with surface area values similar to that of the commercial activated carbon adsorbent. The bamboo adsorbent has also been evaluated to perform similar to the commercial activated carbon for the removal and recovery of Pd (II) from synthetic electroless plating solutions. Also, a conceptual cost analysis indicated and affirmed towards the potential of the BSAC adsorbents for waste water treatment applications.  相似文献   

14.
This article provides evidence that jatropha seed coat residues can be used as a carbon source for preparing activated carbons that have good adsorption properties for iodine and methylene blue. Activated carbons were prepared using three different methods of activation, physical, chemical, and physico-chemical, for a range of activation temperatures (600°, 700°, 800°, and 900°C) and activation hold times (1, 2, and 3 h). The highest BET surface area (1479 m2 g?1) and the highest iodine adsorption (1511 mg g?1) were obtained with physico-chemical activation at a temperature of 900°C and a hold time of 2 h. This activated carbon gave higher BET surface area and iodine adsorption than commercial activated carbon (1169.1 m2 g?1 and 1076 mg g?1). The activated carbons prepared by physico-chemical activation at 900°C and 2 h were then tested for adsorption of methylene blue at a range of concentrations of methylene blue (100, 200, 300, 400, and 500 mg L?1). It was found that a Langmuir isotherm gave a better fit (R 2 = 0.999) to the observed adsorptions than a Freundlich isotherm (R 2 = 0.884). For the adsorption kinetics, a pseudo-second-order model gave a better fit (R 2 > 0.998, Δq e  = 3.7%) than a pseudo-first-order model (R 2 ≈ 0.95, Δq e  = 85.6%). These results suggest that chemisorption is the rate-controlling step for the adsorption of methylene blue. The experimental results show that jatropha seed coat is a lignocellulosic waste precursor for preparation of activated carbon that is an alternative source for preparation of commercial-grade activated carbons.  相似文献   

15.
Hydrothermal method was used to synthesize TiO2 nanotubes (TNTs), which are considered as a novel adsorbent with high surface area and adsorption capacity. Different methods including X-ray diffraction (XRD), transmission electron microscope (TEM) and Brunauer–Emmett–Teller (BET) analysis were used to investigate and identify synthesized TNTs. The adsorption capacity of TNTs was investigated with regard to removing Basic Violet 2 (BV2) as a model organic pollutant from aqueous solution. The mean outer, inner diameter and thickness of the TNTs were found to be approximately 9, 4 and 2.5 nm, respectively. BET–BJH method was used for measuring specific surface area and pore volume of the TNTs which turned out to be 200.38 m2 g?1 and 0.44 cm3 g?1, respectively. The results of the study indicated synthesized TNTs may be considered as efficient and effective adsorbent for removing BV2 (75.63%) from aqueous solution. The impact of the operational variables, i.e. initial BV2 concentration (2–20 mg L?1), dosage of adsorbent (0.01–0.6 g), and pH (2–8) in relation to the adsorption capacity of BV2 onto TNTs were investigated. The experimental results of the study were meticulously taken into consideration for discussing and analyzing the adsorption isotherms and kinetics. It was found that the collected experimental data regarding the kinetic and isotherm examinations were compatible and well-matched with the pseudo-first order kinetic model and Langmuir isotherm model (R 2?=?0.9634).  相似文献   

16.
《分离科学与技术》2012,47(16):2381-2390
The present investigation describes the potential of acid activated papaya leaf for the adsorption of methyl orange (MO) dye from aqueous solution. The FT-IR analysis indicated the presence of a wide variety of functional groups on the surface of the activated papaya leaf. Scanning electron microscopy and Electron dispersion X-ray techniques indicated the morphological behavior of adsorption onto the adsorbent, and weight percentage of chemical compositions available on the surface of adsorbent. The parameters, such as pH, contact time, and agitation rate giving the highest adsorption efficiency were obtained at 2, 120 min, and 150 rpm, respectively. The Langmuir model was found to represent the isotherm data better than other isotherms studied. Batch adsorption studies, based on the assumption of a pseudo first-order, Elovich Equation, and the pseudo second-order showed that the kinetic data followed closely a pseudo second-order mechanism. The adsorption capacity of activated papaya leaf for the removal of MO dye was found to be 333.34 mg/g. These showed that papaya leaf could be considered as a good and economical substitute of commercial activated carbon.  相似文献   

17.
《分离科学与技术》2012,47(6):886-895
Activated carbon prepared from palm shell by phosphoric acid impregnation, at significantly favorable experimental conditions is characterized for the porous nature and adsorption of methylene blue dye molecules. The activation is carried out using a 2-stage activation process with the activation in a self-generated atmosphere. An activation temperature of 500°C, with an activation time of 75 minutes using a phosphoric acid impregnation ratio of 3 has yielded an activated carbon having unique characteristics. An activated carbon with a yield of 48%, total pore volume of 1.9 cm3/g, surface area of 1956 m2/g, an average pore diameter of 3.8 nm, with the ratio of the mesopore to the total surface area in excess of 75% has been prepared. The activated carbon exhibits a high methylene blue equilibrium adsorption capacity of 438 mg/g with the adsorption isotherm increasing with an increase in the adsorption temperature. Among the various adsorption isotherm models, the Langmuir model is able to explain the adsorption process well, evidenced by the proximity of the model with the experimental data. Among the different kinetic models tested with the experimental kinetic data, a pseudo-second-order model is found to fit the experimental data with close proximity.  相似文献   

18.
In present study,we report the preparation of coconut shell activated carbon as adsorbent and its appli-cation for Bi(Ⅲ) removal from aqueous solutions.The developed adsorbent was characterized with scanning elec-tron microscope(SEM),Fourier Transform Infrared(FTIR),C,H,N,S analyzer,and BET surface area analyzer.The parameters examined include agitation time,initial concentration of Bi(Ⅲ),adsorbent dose and temperature.The maximum adsorption of Bi(Ⅲ)(98.72%) was observed at 250 mg·L-1 of Bi(Ⅲ) and adsorbent dose of 0.7 g when agitation was at 160 r·min-1 for 240 min at(299±2) K.The thermodynamic parameters such as Gibb’s free energy(△Gθ),enthalpy(△Hθ) and entropy(△Sθ) were evaluated.For the isotherm models applied to adsorption study,the Langmuir isotherm model fits better than the Freundlich isotherm.The maximum adsorption capacity from the Langmuir isotherm was 54.35 mg?g?1 of Bi(Ⅲ).The kinetic study of the adsorption shows that the pseudo second order model is more appropriate than the pseudo first order model.The result shows that,coconut shell ac-tivated carbon is an effective adsorbent to remove Bi(Ⅲ) from aqueous solutions with good adsorption capacity.  相似文献   

19.
Eucalyptus sawdust was used as a precursor to prepare activated carbon using NaOH as a chemical activation agent. The effect of preparation conditions on the characteristics of the produced activated carbon used as an adsorbent was investigated. The performance of the activated carbon was characterized by N2 adsorption–desorption isotherms, Brunauer–Emmett–Teller equation, Barett–Joyner–Halenda equation, scanning electron microscopy and Fourier transform infrared analysis. When the eucalyptus sawdust mass was 30.00 g, with particle sizes between 0.25 and 0.42 mm, and the sawdust was heated and charred before activation by NaOH, the optimized conditions for the preparation of activated carbon was found to be as follows: mass ratio of NaOH to eucalyptus sawdust, 1:2; activation time, 30 min; and activation temperature, 700 °C. The Iodine number and BET surface area of the produced activated carbon was 899 and 1.12 × 103 m2 g?1, respectively, with a 13.3 % yield. Activated carbon exhibits adsorption isotherms of type IV. The total pore volume, micropore volume and average pore diameter were recorded as 0.636, 0.160 cm3 g?1 and 2.27 nm, respectively. The pore structure of the activated carbon is mainly mesoporous. Carbonyl and hydroxyl groups may also exist on the activated carbon surface.  相似文献   

20.
《分离科学与技术》2012,47(1):155-163
Adsorbents prepared from pistachio nut shell, an agricultural waste biomass, were successfully used to remove Acid Violet 17 from an aqueous solution. The activated carbons PNS1, PNS2, and PNS3 were characterized by scanning electron microscope (SEM), Fourier Transform – Infra Red spectroscopy (FTIR) and (BET). The effect of pH, adsorbent dosage, and temperature on dye removal was studied. Maximum color removal was observed at pH 2. The adsorption increased with the increase in adsorbent dosage. As the adsorption capacity increased with the increase in temperature, the process was concluded to be endothermic. The experimental data were analyzed by the Langmuir and Freundlich isotherm models of adsorption. Equilibrium data fitted well with the Langmuir model. The rates of adsorption confirmed the pseudo-second order kinetics with good correlation values. The results indicated that the activated carbon prepared from pistachio nut shell can be effectively used for the removal of Acid Violet 17 from aqueous solution.  相似文献   

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