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1.
In the present study, Oreganum onites L. stalks in natural and chemically modified with HNO3 and H3PO4 used as adsorbent for removal of both acidic and basic dyes from waters. The adsorption was studied as a function of pH and contact time by batch method. All tested biosorbents were characterized by FT‐IR, scanning electron microscopy, and measuring the pH dependence of the zeta potential. The adsorption isotherms were fitted to Langmuir isotherm. The maximum adsorption capacity of dyes was 280.73 mg g?1 for Basic Red 18, 147.06 mg g?1 for methylene blue and 112.36 for Acid Red 111, which is comparable to that of other lignocellulosic materials. The modification process was considerably increased the biosorption capacity of lignocellulosic material, resulting in a 56–63% increase in the biosorption capacity of basic dyes and a 125% increase in the biosorption capacity of acidic dye. The present study illustrated that the most effective factors in the adsorption of basic dye were surface charge and acidic groups on lignocellulosic biosorbents, while non‐electrostatic forces as well as electrostatic forces were also effective in the adsorption of acidic dye. In conclusion, Oreganum stalks can be considered as a very prospective adsorbent for the removal of tested basic and acidic dyes.  相似文献   

2.
The effects of various parameters such as initial concentration, adsorbent loading, pH, and contact time on kinetics and equilibrium of adsorption of Cd2+ metal ion from its aqueous solution by castor seed hull (CSH) and also by activated carbon have been investigated by batch adsorption experiments. The amount of adsorption increases with initial metal ion concentration, contact time, solution pH, and the loading of adsorbent for both the systems. Kinetic experiments indicate that adsorption of cadmium metal ion on both CSH and on activated carbon consists of three steps – a rapid adsorption of cadmium metal ion, a transition phase, and an almost flat plateau region. This has also been confirmed by the intraparticle diffusion model. The lumped kinetic results show that the cadmium adsorption process follows a pseudo‐second order rate law. The kinetic parameters including the rate constant are determined at different initial metal ion concentrations, pH, amount, and type of adsorbent, respectively. The Langmuir and Freundlich adsorption isotherm models are used to describe the experimental data. The Langmuir model yields a better correlation coefficient than the other model. A comparison of the monolayer adsorption capacity (qm) of CSH, activated carbon, and several other reported adsorbents has been provided. The value of separation factor (RL) calculated from the Langmuir equation also gives an indication of favorable adsorption of the metal ion. From comparative studies, it has been found that CSH is a potentially attractive adsorbent than commercial activated carbon for cadmium metal ion (Cd2+) removal.  相似文献   

3.
Batch sorption technique was carried out for the removal of anionic dye Congo red (CR) from aqueous solution using raw rectorite (R‐REC) and organified rectorite (CTA+‐REC) modified by cetyltrimethylammonium bromide (CTAB) as adsorbents. The effects of organification degree of CTA+‐REC as well as the process parameters including the pH of dye solution, sorption time, and initial dye concentration on adsorption capacity for CR were investigated and the sorption kinetics was also evaluated. The results showed that the sorption behaviors of R‐REC and CTA+‐REC for CR followed pseudo‐second‐order kinetic model and the sorption equilibrium data perfectly obeyed the Langmuir isotherm. The thermodynamic parameters including entropy of sorption (ΔS0), enthalpy of sorption (ΔH0), and Gibbs free energy of sorption (ΔG0) were obtained and analyzed. Fourier transform infrared study revealed that a chemisorption process occurred between CR and CTA+‐REC. REC modified by cationic surfactants showed the higher adsorption capacities for CR compared to R‐REC and in theory would be used as an efficient and promising adsorbent for the removal of anionic dyes in wastewater treatment.  相似文献   

4.
Using batch method, the adsorption of thallium(I) ions from aqueous solutions on eucalyptus leaves powder, as a low cost adsorbent, was studied. The effect of various modification of considered adsorbent on the adsorption percentage of Tl(I) is an important feature of this study. The results showed that the unmodified and acidic modified adsorbent are the poor adsorbents for the Tl(I) ions while basic modified adsorbent is a suitable adsorbent. Also, the effect of some experimental conditions such as solution initial pH, agitation speed, contact time, sorbent dosage, temperature, particle size, and thallium initial concentration was studied. The results showed that the adsorption percentage depends on the conditions and the process is strongly pH‐dependent. The satisfactory adsorption percentage of Tl(I) ions, 81.5%, obtained at 25 ± 1°C. The equilibrium data agreed fairly better with Langmuir isotherm than Freundlich and Temkin models. The value of qm that was obtained by extrapolation method is 80.65 mg g?1. Separation factor values, RL, showed that eucalyptus leaves powder is favorable for the sorption of Tl(I). The negative values of ΔH0 and ΔS0 showed that the Tl(I) sorption is an exothermic process and along with decrease of randomness at the solid–solution interface during sorption, respectively.  相似文献   

5.
Activated carbons prepared from sunflower seed hull have been used as adsorbents for the removal of acid blue 15 (AB‐15) from aqueous solution. Batch adsorption techniques were performed to evaluate the influences of various experimental parameters, e. g., temperature, adsorbent dosage, pH, initial dye concentration and contact time on the adsorption process. The optimum conditions for AB‐15 removal were found to be pH = 3, adsorbent dosage = 3 g/L and equilibrium time = 4 h at 30°C. The adsorption of AB‐15 onto the adsorbent was found to increase with increasing dosage. It was found from experimental results that the Langmuir isotherm fits the data better than the Freundlich and Temkin isotherms. The maximum adsorption capacity, Qm (at 30°C) was calculated for SF1, SF2, and SF3 as 75, 125 and 110 mg g–1 of adsorbent, respectively. It was found that the adsorption follows pseudo‐second order kinetics. The thermodynamic parameters such as ΔG°, ΔH°, and ΔS° were also evaluated. The activated carbons prepared were characterized by FT‐IR, SEM and BET analysis.  相似文献   

6.
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   

7.
This study aims to remove of Cu2+, Cd2+, and Pb2+ ions from solution and to investigate the adsorption isotherms, adsorption kinetics, and ion‐exchange affinities of these metals using waste activated sludge (AS) biomass. The adsorptions of the metals on biomass were optimal at an acidic pH value of 6.0 based on its monolayer capacities. Maximum monolayer capacities of AS biomass (qmax) were calculated as 0.478, 0.358, and 0.280 mmol g?1 for Cu2+, Cd2+, and Pb2+, respectively, and the adsorption equilibrium time was found as 60 min for each metal. The adsorbed amount of metal rose with increasing of initial metal ion concentration. The equilibrium adsorption capacity of AS for initial 0.25 mmol L?1 metal concentration was determined as 0.200, 0.167, and 0.155 mmol g?1 for Cu2+, Cd2+, and Pb2+ ions, respectively. These relevant values were determined as 0.420, 0.305, and 0.282 mmol g?1 for Cu2+, Cd2+, and Pb2+ ions, respectively, when initial metal concentration was 0.50 mmol L?1. In the multi‐metal sorption system, the adsorption capacity of AS biomass was observed in the order of Cu2+ > Cd2+ > Pb2+. In the presence of 100 mmol L?1 H+ ion, the order of ion‐exchange affinity with H+ was found as Cu2+ > Cd2+ > Pb2+. The adsorption kinetics were also found to be well described by the pseudo‐second‐order and intraparticle diffusion models. Two different rate constants were obtained as ki1 and ki2 and ki1 (first stage) was found to be higher than ki2 (second stage).  相似文献   

8.
The adsorption of three cationic dyes (rhodamine B, RB; crystal violet, CV; and malachite green, MG) onto termite feces, a low‐cost adsorbent, was investigated. The adsorbent was characterized by IR spectroscopy, point of zero charge measurement, and the Boehm titration method. The adsorption follows the pseudo‐second‐order kinetic model and the Langmuir–Freundlich isotherm with maximum adsorption capacities of 95.53 mg g?1 (RB), 75.71 mg g?1 (CV), and 44.78 mg g?1 (MG). The study of thermodynamics showed that the adsorption is a spontaneous and endothermic process. This works suggest that termite feces can be used as a new low‐cost adsorbent for cationic dye removal.  相似文献   

9.
The present study was aimed at removing cadmium ions from aqueous solution through batch studies using adsorbents, such as, granular activated carbon (GAC) and activated clay (A‐clay). GAC was of commercial grade where as the A‐clay was prepared by acid treatment of clay with 1 mol/L of H2SO4. Bulk densities of A‐clay and GAC were 1132 and 599 kg/m3, respectively. The surface areas were 358 m2/g for GAC and 90 m2/g for A‐clay. The adsorption studies were carried out to optimize the process parameters, such as, pH, adsorbent dosage, and contact time. The results obtained were analyzed for kinetics and adsorption isotherm studies. The pH value was optimized at pH 6 giving maximum Cd removal of 84 and 75.2% with GAC and A‐clay, respectively. The adsorbent dosage was optimized and was found to be 5 g/L for GAC and 10 g/L for A‐clay. Batch adsorption studies were carried out with initial adsorbate (Cd) concentration of 100 mg/L and adsorbent dosage of 10 g/L at pH 6. The optimum contact time was found to be 5 h for both the adsorbents. Kinetic studies showed Cd removal a pseudo second order process. The isotherm studies revealed Langmuir isotherm to better fit the data than Freundlich isotherm.  相似文献   

10.
Adsorptive removal of EDTA (ethylenediaminetetraacetic acid) from aqueous solution was studied using steam pyrolyzed activated carbon. Rubber wood sawdust, obtained from a local timber facility at Kodangavila, Trivandrum, Kerala, India was used as the precursor for the production of the activated carbon. Batch adsorption experiments were employed to monitor and optimize the removal process. The experimental parameters, i. e., solution pH, agitation time, initial EDTA concentration and adsorbent dosage, affecting the adsorption of EDTA onto sawdust activated carbon (SDAC) were optimized. The inner core mechanism for the interaction between EDTA and SDAC, which resulted in the adsorption process, was also discussed. The change in amount of EDTA adsorbed onto SDAC and CAC (commercial activated carbon) was compared over a wide range of pH (2.0–8.0). The maximum removal of EDTA took place in the pH range of 4.0–6.0 for SDAC and 5.0–5.5 for CAC, which demonstrates the effectiveness of the former adsorbent. Kinetic as well as equilibrium studies were performed to determine the rate constant and adsorption capacity, respectively. The adsorption kinetic data was fitted with pseudo‐first‐order kinetics and the equilibrium data was shown to follow the Langmuir isotherm model. These observations explain the formation of a monolayer of EDTA on the surface of SDAC as confirmed by the slow approach to equilibrium after 4 h of contact time. The adsorption capacity of SDAC for the removal of EDTA was 0.526 mmol/g and is seen to be greater than that of CAC and other reported adsorbents (0.193–0.439 mmol/g). Finally, it is clear that the production of steam pyrolyzed activated carbon in the presence of K2CO3 greatly enhanced EDTA removal and resulted in a product with possible commercial value for wastewater treatment strategies.  相似文献   

11.
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   

12.
Lepidocrocite (γ‐FeOOH) nanoparticles were synthesized from iron(II) sulfate solution and characterized using X‐ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform‐IR (FT‐IR), nitrogen adsorption, and point of zero charge pH (pHPZC) analyses. TEM, XRD, and FT‐IR analyses proved the synthesis of nano‐lepidocrocite. Surface area and pHPZC of the synthesized lepidocrocite were 68.1 m2 g?1 and 4.8, respectively. Utilization of the synthesized lepidocrocite in the adsorption of Lanacron brown S‐GL (LBS‐GL) from aqueous solutions was investigated, and the effect of lepidocrocite dosage, pH, temperature, and contact time on this process were optimized and modeled using response surface methodology approach. The lepidocrocite dosage of 0.015 g, pH 3.5, temperature of 38°C, and contact time of 100 min were determined as optimum adsorption conditions. Isotherm and kinetics of the adsorption process were analyzed at the optimum conditions. The equilibrium data were fitted well to the Langmuir isotherm model. The maximum monolayer adsorption capacity was 528.21 mg g?1. The adsorption process was described by the pseudo‐second‐order kinetic model. Furthermore, the effect of pH on the desorption of LBS‐GL was investigated. High LBS‐GL desorption efficiency was achieved at a high pH value.  相似文献   

13.
In the current study the application of organo‐modified bentonite for the adsorption of mycotoxins (aflatoxin B1, citrinin, patulin, and zearalenone) is presented. The modification of clays is carried out using benzyl‐tri‐n‐butyl ammonium bromide (BTB), benzethonium chloride (BTC), and dioctyl sodium sulfosuccinate (DSS). Various experimental parameters such as pH, time, adsorbent dose, and mycotoxins concentration are thoroughly studied. The modified clays (B‐BTB, B‐BTC and B‐DSS) are characterized by X‐ray fluorescence, X‐ray diffraction, and Fourier transform infrared spectroscopy. The results depicted the high detoxification efficiency (≈99%) of modified clays for the removal of mycotoxins under optimized conditions (pH 5, time: 30 min, adsorbent amount: 50 mg). The adsorption capacities of modified clays are found in the order of: B‐BTC (AFB1: 18.02, CIT: 18.35, PAT: 18.21, ZEA: 18.09 mg g?1) > B‐BTB (AFB1: 17.7, CIT: 18.11, PAT: 17.95, ZEA: 17.90 mg g?1) > B‐DSS (AFB1: 17.5, CIT: 18.02, PAT: 17.86, ZEA: 17.80 mg g?1). The obtained results fitted well with thermodynamic, isothermal (Langmuir) and pseudo‐second order kinetics. Low cost organo‐modified bentonite shows the promise in mitigating mycotoxin contamination, which could improve food safety and reduce environmental contamination.  相似文献   

14.
Biomass char (BC) deriving from fast pyrolysis of biomass was a potential adsorption material due to its relative high fixed‐carbon content and the inherent porous structures. Adsorption of phosphate from aqueous solution by BC was investigated in this paper. The results showed that the adsorption capacity of BC was dependent on pyrolysis conditions, such as temperature and holding time. The maximum adsorption capacity for phosphate was approximately 15.11 mg g?1 at 298 K. The pseudo‐second order model of the adsorption kinetics indicated that the adsorption process was complex and several mechanisms were involved. Equilibrium isotherm was satisfactorily followed the Freundlich isotherm model. The KF value in Freundlich equation gradually increased with elevating temperature. Moreover, the thermodynamic constants: ΔG0, ΔH0, and ΔS0 were evaluated as ?6.49 kJ mol?1 (at 298 K), 13.41 kJ mol?1, and 66.70 J mol?1 K?1, respectively. Phosphate adsorption onto BC was spontaneous and endothermic. As a waste, BC was a potentially attractive adsorbent for phosphate removal from aqueous solution with low cost and high capability.  相似文献   

15.
Waste beer yeast was modified by pyromellitic dianhydride to improve its adsorption capacity for rhodamine B (RhB). Results showed that the adsorption capacity of the modified biomass for RhB was 600 mg g?1, which was about five times than that obtained on the unmodified biomass. Dye loaded modified biomass was regenerated by (1) a common eluent: HNO3 solution and (2) a self‐cleaning eluent: TiO2 hydrosol, while the pH of both systems varied from 1 to 4. Desorption experimental results showed that low desorption rates were obtained in both systems after the first desorption cycle. A large volume of HNO3 solution was needed to obtain high desorption rate, and a concentrated solution of RhB was left, which brought a secondary pollution. As a self‐cleaning eluent, acid TiO2 hydrosol acted both as eluent and photocatalyst. The desorbed RhB could be photodegraded under sunlight irradiation and the same hydrosol could be used in the next desorption cycle without losing its activity, which could economize large volumes of solvent. The results showed an adsorption capacity of the regenerated biosorbent for RhB of 450 mg g?1 by using hydrosol with pH 2 as eluent after four desorption/photodegradation cycles.  相似文献   

16.
This study investigates structural and adsorption properties of the powdered waste shells of Rapana gastropod and their use as a new cheap adsorbent to remove reactive dye Brilliant Red HE‐3B from aqueous solutions under batch conditions. For the powder shells characterization, solubility tests in acidic solutions and X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDX), Fourier transform IR spectroscopy (FT‐IR) and thermogravimetric analyses were performed. The results revealed that the adsorbent surface is heterogeneous consisting mainly from calcium carbonate layers (either calcite or aragonite) and a small amount of organic macromolecules (proteins and polysaccharides). The dye adsorptive potential of gastropod shells powder was evaluated as function of initial solution pH (1–5), adsorbent dose (6–40 g L?1), dye concentration (50–300 mg L?1), temperature (5–60°C), and contact time (0–24 h). It was observed that the maximum values of dye percentage removal were obtained at the initial pH of solution 1.2, shells dose of 40 g L?1, dye initial concentration of 50–50 mg L?1 and higher temperatures; the equilibrium time decreases with increasing of dye concentration. It is proved that the waste seashell powder can be used as low cost bioinorganic adsorbent for dyes removal from textile wastewaters.  相似文献   

17.
This study investigates the potential use of activated carbon prepared from the peel of Cucumis sativa fruit for the removal of malachite green (MG) dye from simulated wastewater. The effects of different system variables, adsorbent dosage, initial dye concentration, pH, and contact time were investigated and optimal experimental conditions were ascertained. The results showed that when the amount of the adsorbent increased, the percentage of dye removal increased accordingly. Optimum pH value for dye adsorption was 6.0. Maximum dye was sequestered within 50 min of the start of every experiment. The adsorption of MG followed the pseudo‐second‐order rate equation and fits the Langmuir, Freundlich, Dubinin–Radushkevich (D–R), and Tempkin equations well. The maximum removal of MG was obtained at pH 6 as 99.86% for adsorbent dose of 1 g/50 mL and 25 mg L?1 initial dye concentration at room temperature. Activated carbon developed from the peel of C. sativa fruit can be an attractive option for dye removal from diluted industrial effluents since test reaction made on simulated dyeing wastewater showed better removal percentage of MG.  相似文献   

18.
Adsorption of Dichloromethane and 1,1,1-Trichloroethane from Synthetic Wastewaters with Polymeric Adsorbents and Activated Carbons Isotherms, kinetics, and dynamics of adsorption of dichloromethane and 1,1,1-trichloroethane from synthetic wastewaters onto novel polymeric adsorbents were investigated in comparison to traditional polymeric adsorbents and activated carbons. The polymeric adsorbents and the activated carbons showed no large differences in adsorption kinetics, whereas the novel, crosslinked polymeric adsorbents exhibited at times higher adsorption capacities than the traditional, not crosslinked polymeric adsorbents and activated carbons.  相似文献   

19.
The potential of MCM‐41 for the removal of cationic dyes from water solution was evaluated using sodium dodecyl sulfate (SDS) for the surface modification of this mesoporous material. Admicelle structures formed on the surface of the calcined MCM‐41 are capable of removing organic pollutants and cationic species from water environment. The structural, textural, and surface chemical characteristics of the prepared SDS‐modified MCM‐41 (SDS‐MCM‐41) were studied. The adsorption capacity of SDS‐MCM‐41 was evaluated for methylene blue (MB) as a target cationic dye. Equilibrium adsorption isotherm data were manipulated employing nonlinear regression analysis. The Langmuir, Freundlich, and Sips isotherm models were examined. The adsorption data were well fitted to both Langmuir and Sips isotherm models. The maximum adsorption capacity of SDS‐MCM‐41 for MB, based on Langmuir and Sips models, were 290.8 and 297.3 mg g?1, respectively. Ethanol was found to be an effective solvent for partial regeneration of the adsorbent.  相似文献   

20.
Waste red mud and natural pumice/volcanic slag particles were surface modified and their selenium adsorption from waters was investigated. Acid activation/heat treatment of original red mud (ORM) particles significantly increased their micropore and external surface area and cumulative volume of pores. Iron oxide coating of pumice/slags and acid activation of ORM decreased their pHpzc values and increased surface acidity. Selenite/selenate adsorption on iron oxide surfaces and acid activated red mud (AARM) was very fast with approximately first‐order adsorption kinetics. Iron oxide coating of pumice/slag and acid activation of ORM particles significantly enhanced their selenite and selenate uptakes. Maximum Se adsorption capacities as high as 6.3 (mg Se/g adsorbent) were obtained by AARM. The extent of selenate uptakes by the surface modified particles was generally lower than those of selenite. Due to competition among Se species and other background water matrix for iron oxide adsorption sites, reduced selenite/selenate uptakes were found in natural water compared to single solute tests. Higher Se uptakes by iron oxide surfaces were found at pH 7.5 compared to pH 8.9, due to increased electrostatic repulsion among iron oxides and Se species at higher pH. The most effective adsorbents among the tested 17 different particles for Se uptake were AARM and iron oxide coated pumice. Se concentrations less than drinking water standards (5–10 µg/L) can be achieved by these particles. These low‐cost, natural, or recyclable waste particles appear to be promising adsorbents for Se removal after their surface modification.  相似文献   

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