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1.
Nanosilica particles modified by Schiff base ligands 3-methoxy salicylaldimine propyl triethoxysilane (MNS1), 5-bromo salicylaldimine propyl triethoxysilane (MNS2) and 3-hydroxy salicylaldimine propyl triethoxysilane (MNS3) were prepared, and their potential for separation of copper, lead, zinc, cadmium, cobalt and nickel ions from aqueous solutions was examined. The effect of parameters influencing adsorption efficiency including aqueous-phase pH, amount of adsorbent, stirring time and initial concentration of the metal ions was assessed and discussed. Although MNS1 and MNS3 removed lead ions efficiently, all adsorbents showed strong selectivity toward copper ions. It was shown that, under some circumstances, MNS3 decreased the amount of other ions, particularly cobalt, in the aqueous phase. The adsorbents were also applied for removal of copper and lead ions from real samples. Possible quantitative desorption of the metal ions loaded onto the adsorbents suggests their multiple uses in adsorption–desorption process. Investigation of temperature dependency of the process led to determination of the ΔH°, ΔS° and ΔG° values. This investigation indicates that the adsorption of copper ions onto the all studied adsorbents and lead ions onto MNS1 and MNS3 is endothermic. The Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherms were tested to describe the equilibrium data. Pseudo-first-order, pseudo-second-order, Elovich and intra-particle diffusion equations were applied to study the kinetics of copper and lead adsorption onto the modified nanoparticles. This investigation indicates that the process for all adsorbents follows pseudo-second-order kinetics and suggests a chemisorption mechanism for the adsorption processes by the studied adsorbents.  相似文献   

2.
Homogenized samples of raw clays resulting from two (2) different lots of natural clays from Maghnia (Algeria) have been assessed for their potential use in the removal of Pb2+ and Zn2+ ions from industrial liquid wastes (LW). Raw and acid-activated samples have been characterized by powder X-ray diffraction, FT-IR spectroscopy, electron microscopy (SEM), and X-ray fluorescence (XRF) and used as adsorbents for the removal of Pb2+ and Zn2+ ions from aqueous system using adsorption method under different conditions. The effect of factors including contact time, pH, and dosage on the adsorption properties of Pb2+ and Zn2+ ions onto clays was investigated at 25 °C. The obtained results revealed that the removal percentages of Pb2+ and Zn2+ ions, from both aqueous solution (AS) and LW, were varying between 90 and 98% for 40 min and optimal pH values ranged from 5 to 6 for Pb2+ and Zn2+ ions, respectively. The kinetics of both Pb2+ and Zn2+ ion adsorption fitted well with the pseudo-second-order model. Langmuir, Freundlich, and Temkin adsorption isotherms were used, and their constants were evaluated. The values of thermodynamic parameters, ΔH°, ΔS°, and ΔG° indicated that the adsorption of Pb2+ and Zn2+ ions was spontaneous and exothermic process in nature. The adsorption and desorption isotherms indicated that Pb2+ and Zn2+ adsorption to raw clays was reversible. The experimental results obtained showed that the raw clays from Maghnia (Algeria) had a great potential for removing Pb2+ and Zn2+ ions from industrial liquid wastes using adsorption method.  相似文献   

3.
A novel polyurethane foam/organobentonite/iron oxide nanocomposite adsorbent was successfully prepared via in situ polymerization of toluene diisocyanate and polyol in presence of 5 wt% organobentonite/iron oxide. The obtained nanocomposite was characterized in detail, and the results revealed that the clay layers are exfoliated and/or intercalated in the polymer matrix forming a nanocomposite structure. The application of the prepared nanocomposite for adsorption of cadmium ions from aqueous solution was tested as a function of various experimental parameters using batch procedures. Adsorptive removal of Cd(II) onto the nanocomposite attained maximum at adsorbent content 1.5 g/L, pH 6, and the equilibrium was established within 60 min. Kinetic studies showed that the experimental data fit very well to pseudo-second-order model, and the adsorption process proceeds through three steps. It was found that external liquid film and intraparticle diffusion steps deeply affect the rate of Cd2+ ions adsorption onto the synthesized nanocomposite. Langmuir isotherm model fitted the adsorption data better than Freundlich with a maximum adsorption capacity (q m) for Cd(II) equal to 78 mg/g under the specified experimental conditions. The synthesized nanocomposite afforded effective extraction for Cd2+ ions from natural water samples and excellent reusability feature. This study declares the potential efficiency of a new clay/polymer nanocomposite as alternative for wastewater remediation.  相似文献   

4.
This work aimed to investigate the adsorption characteristics, both kinetically and thermodynamically, of Cu(II) and Pb(II) removal from aqueous solutions onto mixed-waste activated carbon, as well as to study the competitive behavior found in mixed heavy metal solution systems. This study shows that activated carbon prepared from mixed waste is an effective adsorbent for the removal of Cu(II) and Pb(II) from aqueous solutions, with the aim of detoxifying industrial effluents before their safe disposal onto water surfaces. The adsorption process was characterized in terms of kinetic and thermodynamic studies. In addition, the influence of presence of Cu(II) and Pb(II) in a competitive system was investigated. The results showed that the maximum adsorption capacities were gained at a pH of 6 with a contact time of 180 min, a metal solution concentration of 300 ppm, and an adsorbent dose of 0.3 g/L. The adsorption process was found to follow a pseudo-first-order kinetic model. Thermodynamic parameters such as ΔG o, ΔH o, and ΔS o showed that the sorption process was spontaneous and endothermic in nature. A competitive study demonstrated the applicability of mixed-waste activated carbon to adsorb Cu(II) and Pb(II) from a solution of mixed metals. In addition, the adsorption capacity was found to be as effective as other adsorbents reported in the literature. The developed adsorptive removal procedure was applied for treatment of real wastewater samples and showed high removal efficiency.  相似文献   

5.
This study assesses the ability of two low-cost adsorbents made from waste of Rapanea ferruginea treated with ethanol (WRf) and its H2SO4-treated analog (WRf/H2SO4) for the removal of two cationic dyes methylene blue (MB) and crystal violet (CV) from aqueous solutions. The adsorbent was characterized by scanning electron microscopy, Fourier transform infrared spectrometry, thermogravimetric analysis, point of zero charge (pHpzc), specific surface, and functional groups. The adsorption of dye onto the adsorbents was studied as a function of pH solution (2–12), contact time (up to 120 min) and initial concentration (20–120 mg/L), and temperature (25, 35, and 55 °C). The influence of these parameters on adsorption capacity was studied using the batch process. The response surface methodology (RSM) was used in the experimental design, modeling of the process, and optimizing of the variables and was optimized by the response involving Box–Behnken factorial design (15 runs). The results show that the data correlated well with the Sips isotherm. The maximum adsorption capacities of MB and CV onto WRf were found to be 69 and 106 mg/g, and onto WRf/H2SO4, the adsorption capacities were 33 and 125 mg/g, respectively. The kinetic data revealed that adsorption of cationic dyes onto the adsorbents closely follows the pseudo-second-order kinetic model. Regression analysis showed good fit of the experimental data to the second-order polynomial model, with coefficient of determination (R2) values for MB (R2?=?0.9685) and MB (R2?=?0.9832) for WRf and CV (R2?=?0.9685) and CV (R2?=?0.9832) for WRf/H2SO4 indicated that regression analysis is able to give a good prediction of response for the adsorption process in the range studied. The results revealed that waste from R. ferruginea is potentially an efficient and low-cost adsorbent for adsorption of MB and CV.  相似文献   

6.
Liners are commonly used in engineered waste disposal landfill to minimize the potential contamination of the aquatic environment. The adsorption behavior of Cu(II) from aqueous solution onto clay admixed with various mix ratios of quarry fines was investigated. The amount of Cu(II) adsorption increases with increase in contact time. The copper removal efficiencies of the composite mixture gradually decrease from 94.53 % (raw clay) to 85.59 % (20 % of quarry fines with clay), and appreciable decrease in percent removal 75.61 % was found with 25 % of quarry fines with clay. The kinetic adsorption data were analyzed by pseudo-first-order, pseudo-second-order, Bhattacharya–Venkobachar and Natarajan–Khalaf kinetic models to classify adsorption process mechanisms. Kinetic experimental data were good agreement with pseudo-second-order kinetic model with the degree of fitness of the data (R 2) 0.9999 for the adsorption of Cu(II). The results revealed that quarry fines can be used with optimum of 20 % replacement of natural clay for removal of Cu(II) as a liner material in landfills.  相似文献   

7.
The remediation of soil, contaminated by organic pollutants, in a cylinder-to-plane dielectric barrier discharge reactor at atmospheric air pressure was reported. Two model organic pollutants were selected; a solid pollutant (2,6-dichloropyridine) and a liquid pollutant (n-dodecane). The effects of the contaminant’s initial concentration and state, the energy consumption, and the soil type on the pollutant removal efficiency were investigated. To that scope, various contaminated samples of both quartz sand and loamy sandy soil were treated by plasma for various treatment times and initial 2,6-dichloropyridine/n-dodecane concentrations. The results revealed that (1) the removal efficiency of 2,6-dichloropyridine was higher compared to that of n-dodecane at a given plasma treatment time and (2) the removal efficiency increased with the energy density increasing, but decreased as the soil heterogeneity, organic matter and pollutant concentration were enhanced. The main removal mechanism proposed is the evaporation of pollutant molecules coupled with their oxidation by plasma species in the gas and solid/liquid phase.  相似文献   

8.
Evans blue (EB) dye has been successfully removed from aqueous solution through chemisorption process with synthetic layered double hydroxides (LDH) [Zn1?x Al x (OH)2NO3·nH2O, x = 0.2–0.33]. Detailed evaluation of dye adsorption characteristics in aqueous medium has been studied for different layer charged hydroxides. The objective of the study was efficient removal of a dye by LDH and understanding the structure–property relationship of the LDH on its adsorption behaviour. Highest Langmuir monolayer adsorption capacity (Qt) of 113.64 mg g?1 was observed for highest layer charge x = 0.33, and it is higher than previously reported values for the LDH-EB dye system. Under optimized condition, 99% of EB dye is removed from aqueous solution within 60 min at 313 K. The monotonous increase in Qt value with increasing layer charge is correlated with layer charge density (LCD) and lower particle size of the synthetic LDH. The variation in Qt among different layer charged materials is marginal (3.46–4.17%) with respect to the respective anion exchange capacity (AEC) of LDH NO3. The limited contribution of AEC surmises the occurrence of surface-only adsorption and absence of intercalation as validated by the XRD analysis. The spontaneity of the EB dye removal increases with increasing temperature and LCD. The chemisorption nature of the adsorption reaction is well supported by the thermodynamics values.  相似文献   

9.
The removal of caffeine from tap water by F-400 granular activated carbon in fixed-bed adsorption experiments was carried out. Textural and chemical characterization of the adsorbent through N2 adsorption–desorption isotherms, Fourier transform infrared spectrometry, isoelectric point determination and scanning electron microscopy studies was developed in studies previously reported. Caffeine breakthrough curves and total organic carbon profiles at different operation conditions (inlet concentration, volumetric flow rate and mass of adsorbent) were obtained. These experimental results showed a displacement of the natural organic matter from the active sites exerted by caffeine molecules due to their higher affinity to the surface carbon. This behavior led to an overshooting, a local outlet natural organic matter concentration higher than the feed quantity. A competitive effect seems to be observed in the removal of the target compound, decreasing the efficiency of the process. Axial dispersion coefficients and dimensionless numbers were estimated for the caffeine removal onto F-400 activated carbon. Therefore, the regeneration of the adsorbent by adsorption–desorption cycles was studied.  相似文献   

10.
Moringa oleifera seed was used as a biosorbent for the removal of water treatment disinfection by-products, haloethers, trihalomethanes and haloketones from water samples. M. oleifera seed has polar functional groups such as O–H, C=O, C–N and others which facilitate the extraction of these disinfection by-products. Experiments were conducted in batch and fixed bed column modes. Using batch mode, different parameters were optimized such as M. oleifera seed dosage, sample pH, contact time and agitation speed. The effect of the thickness layer and flow rate were also studied using the fixed bed mode. Maximum adsorption occurs using the batch mode with removal efficiencies of 120.5, 114 and 111.5 mg/g for haloethers, trihalomethanes and haloketones, respectively. Adsorption equilibrium followed Langmuir model, and the kinetic data obeyed the pseudo-second-order model, revealing that the M. oleifera seed had higher adsorption capacity than other reported sorbents. Shorter removal time with higher adsorption capacity of disinfection by-products by M. oleifera seed suggests that this material was effective for water treatment, in dealing with the removal of the disinfection by-products considered.  相似文献   

11.
Bimetallic Fe/Ni nanoparticles were synthesized and used for the removal of profenofos organophosphorus pesticide from aqueous solution. These novel bimetallic nanoparticles (Fe/Ni) were characterized by scanning electron microscopy, energy-dispersive X-ray analysis spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The effect of the parameters of initial pesticide concentration, pH of the solution, adsorbent dosage, temperature, and contact time on adsorption was investigated. The adsorbent exhibited high efficiency for profenofos adsorption, and equilibrium was achieved in 8 min. The Langmuir, Freundlich, and Temkin isotherm models were used to determine equilibrium. The Langmuir model showed the best fit with the experimental data (R 2 = 0.9988). Pseudo-first-order, pseudo-second-order, and intra-particle diffusion models were tested to determine absorption kinetics. The pseudo-second-order model provided the best correlation with the results (R 2 = 0.99936). The changes in the thermodynamic parameters of Gibb’s free energy, enthalpy, and entropy of the adsorption process were also evaluated. Thermodynamic parameters indicate that profenofos adsorption using Fe/Ni nanoparticles is a spontaneous and endothermic process. The value of the activation energy (E a = 109.57 kJ/mol) confirms the nature of the chemisorption of profenofos onto Fe/Ni adsorbent.  相似文献   

12.
An activated carbon-impregnated cellulose filter was fabricated, and the capacity to remove dust and volatile organic compounds was evaluated in a laboratory. The adsorption capacities for benzene, toluene, ethyl benzene and m-xylene gases were compared by an adsorption isotherm test conducted as a preliminary test, showing that m-xylene and benzene were the most and least favorable for adsorption onto activated carbon, respectively. Cellulose filters were made with four levels of activated carbon contents, and dust removal was performed with all of the filters showing 99 % and higher efficiencies stable with a small variation during the experiment. Activated carbon content of 5 g in the unit filter area (125 g/m2) was found optimum for benzene, toluene, ethylbenzene and m-xylene removal, as it appeared that higher than 5 g activated carbon content was unnecessary for the improvement of its capacity. With increasing benzene, toluene, ethylbenzene and m-xylene loading, the highest removal rates were determined as 0.33–0.37 mg/cm2 s for as short as 0.0046 s of air filter residence time. The rapid removal was possible because of the high surface area of the activated carbon-impregnated cellulose filter provided by powdered activated carbon, which is distinguished from the granular form in conventional activated carbon towers. As fixed within a cellulose scaffolding structure, the powdered activated carbon performed excellent benzene, toluene, ethylbenzene, and m-xylene adsorption (98.9–100 %), and at the same time, particular matters were removed in average 99.7 % efficiency after being filtered through the cellulose filter sheet.  相似文献   

13.
In this research, the stems of Onopordom Heteracanthom which is a kind of weed were converted to biochar particles, and their characteristics were investigated. The morphology and purity of these particles were examined by SEM and EDX techniques, respectively. Specific surface area was obtained as 5.73 m2 g?1 by BET method. The biochar particles obtained from Onopordom Heteracanthom were evaluated as an adsorbent to remove Cr(VI) from aqueous environments. The effect of some parameters such as initial concentration of Cr(VI), dosage of adsorbent, and pH were investigated on the adsorption capacity of Cr(VI) onto the adsorbent. The equilibrium data were analyzed by various isotherm models. The results revealed that in this process, the adsorption isotherm and kinetics have more conformity with Langmuir isotherm and pseudo-second-order kinetics, respectively. The multi-linearity of the Weber and Morris adsorption kinetic model indicates that the intra-particle diffusion is not merely the rate-controlling step for the whole adsorption process.  相似文献   

14.
An alternative iron removal treatment method using liquid-liquid extraction with the room-temperature ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, as a solvent medium was studied. The chelating agent 1,10-phenanthroline was used as the extractant. The extraction of Fe(III) and Fe(II) was influenced significantly by the pH of the aqueous phase. The successful removal of iron was achieved; more than 95 % of the initial iron concentration was removed from the groundwater samples. However, detailed research is needed before the ionic liquid method can replace the conventional groundwater treatment protocol because the recovery rate was very low upon reuse (approximately 25–60 %). This low recovery was due to the ion exchange process; the appearance of anions from ionic liquids was also detected in groundwater samples.  相似文献   

15.
This paper presents the first attempt to investigate the potential of Tunisian palygorskite-rich clay (Pal-clay) on the effectiveness of a textile dye “Direct orange 34” (DO34) removal. Important parameters which affect adsorption, such as initial solution pH, contact time, adsorbent mass, initial dye concentration, and temperature, were investigated. The raw Pal-clay was characterized using X-ray diffractometer (XRD), X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), cation exchange capacity (CEC), specific surface area (SSA) analysis, and point of zero charge (PZC) determination. The results showed that the Pal-clay has a high selectivity for DO34 and had maximum removal efficiency reaching up to about 91 %. The highest adsorption capacity was obtained at 25 °C and pH of 2. The dye uptake process fitted well to the pseudo-second-order kinetic expression and was best described by the Langmuir and Freundlich isotherms. Intra-particle diffusion studies showed that the adsorption mechanism was not exclusively controlled by the diffusion step and was more likely to be governed by external mass transfer. Thermodynamic parameters such as change in free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) were also calculated. The parameters revealed that the adsorption of dye by the raw clay is spontaneous and exothermic. The results indicate that the Pal-clay has a moderate adsorption capacity towards anionic dye.  相似文献   

16.
In the present study, adsorption of lead (II) ions from aqueous solution by alluvial soil of Bhagirathi River was investigated under batch mode. The influence of solution pH, sorbent dose, initial lead (II) concentration, contact time, stirring rate and temperature on the removal process were investigated. The lead adsorption was favored with maximum adsorption at pH 6.0. Sorption equilibrium time was observed in 60 min. The equilibrium adsorption data were analyzed by the Freundlich, Langmuir, Dubinin–Radushkevich and Temkin adsorption isotherm models. The kinetics of lead (II) ion was discussed by pseudo first-order, pseudo second-order, intra-particle diffusion, and surface mass transfer models. It was shown that the adsorption of lead ions could be described by the pseudo second-order kinetic model. The activation energy of the adsorption process (E a) was found to be ?38.33 kJ mol?1 using the Arrhenius equation, indicating exothermic nature of lead adsorption onto alluvial soil. Thermodynamic parameters, such as Gibbs free energy (?G 0), the enthalpy (?H 0), and the entropy change of sorption (?S 0) have also been evaluated and it has been found that the adsorption process was spontaneous, feasible, and exothermic in nature. The results indicated that alluvial soil of Bhagirathi River can be used as an effective and low cost adsorbent to remove lead ions from aqueous solutions.  相似文献   

17.
Analysis was carried out using tangerine peel aiming its use as a potential adsorbent of eight heavy metal ions (Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn) from aqueous solution. This agricultural waste was tested both in its untreated and also chemically modified form. Based on Fourier transformation infrared spectra, a comparison of biosorbent structure before and after chemical treatment was made. Batch adsorption tests were conducted at different pH and mass of sorbent to examine the influence on the effectiveness of simultaneous removal of tested ions. Kinetic studies were conducted at optimum pH 5.0 and sorbent dosage 300 mg. The pseudo-second-order kinetic model best fit the experimental data with high correlation coefficients (r2 > 0.9997). By optimizing listed parameters, high removal efficiencies (> 89%) were achieved. According to the results obtained in this study, the remediation of water polluted with heavy metals could be done using modified tangerine peel as an agricultural waste material.  相似文献   

18.
Contamination of surface water and groundwater by organic pollutants is a serious problem due to their persistence, bioaccumulation and biomagnification through food webs. Since the removal of dyes from wastewater is considered an environmental challenge and government legislation requires textile wastewater to be treated, therefore there is a constant need to have an effective process that can efficiently remove these dyes. The aim of the present study is to evaluate the potentiality of dried Carpobrotus edulis plant as low-cost adsorbent for the removal of the industrial acid blue 113 dye from aqueous solutions using the batch equilibration technique. The effects of different physicochemical parameters such as adsorbent dose, contact time, initial dye concentration, solution pH and temperature on adsorption rate of anionic AB113 dye on microparticles of dried C. edulis plant were investigated. The experimental data were analyzed by using mathematical models to determine the thermodynamic parameters. The negative values of free energy change indicated the spontaneous nature of the adsorption and negative value of enthalpy change suggested the exothermic nature of the adsorption process. These results indicate that dried C. edulis plant as an environmentally friendly adsorbent could be potentially used for the removal of anionic dyes from aqueous solutions.  相似文献   

19.
Landfill leachate is a high-strength wastewater. If it is not managed properly, it can pollute surrounding environment. The aim of this study is to determine the simultaneous adsorption capacity of iron oxide-coated gravel for metals such as Cd(II), Cu(II), Fe(II), Ni(II) and Zn(II) in high-strength leachate sample. Different operating conditions such as pH, time, and dosages were investigated to determine the kinetics and mechanism of adsorption process. Coating with iron oxide changed the external surface of gravel. The adsorption capacities increased with increased pH, and the optimum pH was found to be 7. High removal rates were observed in a short period of time. The Freundlich model fitted reasonably well to the experimental data, indicating multilayer adsorption process and the heterogeneity of the surface (R 2 ranging 0.57–0.94). The Temkin model fitted well to the experimental data as well (R 2 ranging 0.67–0.98), indicating that the adsorption is an exothermic process. The adsorption of ions was found to obey second-order kinetics, indicating one-step, surface-only adsorption process. The degree of metal adsorption on iron oxide-coated gravel at pH 7 was in the order Cu(II) > Cd(II) > Fe(II) > Zn(II) > Ni(II).  相似文献   

20.
In the present study, Cu (II) ions removal from aqueous solution was intensified by exciting magnetic nanoparticles under inert gas, magnetic field and combination of these two mixing methods in a T-type microchannel. The flow patterns and liquid–liquid two-phase mass transfer were studied in three different magnet distances from mixing channel (3, 6 and 10 mm) and also in the presence of different inert gas flow rates (1, 3 and 5 mL/min). Depending on the mixing method and the flow rate of both phases, several distinct flow patterns were observed including slugs, droplet, parallel and dispersed flows. The performances of mixing techniques for mass transfer enhancement based on relative removal efficiency ratio (λ) and mass transfer coefficient ratio (γ) were compared with simple layout (without nanoparticles, magnetic field and inert gas). The results showed that simultaneous using of inert gas and magnetic field can drive the nanoparticles as mixer. Liquid–liquid mass transfer with 27–62% enhancement in E and 235–285% in K L a compared with plain one was observed.  相似文献   

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