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1.
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   

2.
Investigations of the Adsorptive Separation of Volatile Chlorinated Hydrocarbons (VCHC) from Water with Humic Substance by Novel Polymeric Adsorbents and Activated Carbons. Part I: Isotherms and Kinetics of Adsorption The isotherms and kinetics of adsorption of different volatile chlorinated hydrocarbons (VCHC) (1,2-dichloroethane, 1,1,1-trichloroethane, trichloroethene) and a humic substance from water as well as these VCHC from water with humic substance onto novel polymeric adsorbents (WOFATIT EP 63, DOWEX XUS 43493 and XUS 43546, MACRONET MN 100 and MN 200) were studied in comparison to activated carbons (NORIT ROW 0.8 SUPRA, PRECOLITH BKK 3, HYDRAFFIN CG). It was determined that the novel polymeric adsorbents remove the VCHC well and the humic substance in contrast to the activated carbons only a few. The decrease of the equilibrium loading for the VCHC due to the presence of humic substance is at the activated carbons approximately double as high as at the novel polymeric adsorbents, whereas in the kinetics of adsorption no substantial influences of the humic substance on the mass transfer were determined.  相似文献   

3.
Investigations of the Adsorptive Separation of Volatile Chlorinated Hydrocarbons (VCHC) from Water with Humic Substance by Novel Polymeric Adsorbents and Activated Carbons. Part II: Dynamics of Adsorption In this publication, the dynamics of adsorption of different volatile chlorinated hydrocarbons (VCHC) (1,2-dichloroethane, 1,1,1-trichloroethane, trichloroethene) and a humic substance from water as well as of these VCHC from water with humic substance onto novel polymeric ad-[QJ][HR] sorbents (WOFATIT EP 63, DOWEX XUS 43493, MACRONET MN 100 and MN 200) was studied in comparison to activated carbons (NORIT ROW 0.8 SUPRA, PRECOLITH BKK 3, HYDRAFFIN CG). The obtained breakthrough curves and the following predicted characteristic values reveal that the polymeric adsorbents do not remove or remove the humic substance only with low adsorption capacity in contrast to the activated carbons. At the adsorption of the VCHC from water with humic substance it was determined that the influence of the humic substance on the adsorption capacity is substantially less on polymeric adsorbents than on activated carbons.  相似文献   

4.
Investigating adsorption of methyl parathion on the activated carbons Filtrasorb 400 and F 44 and on the adsorption polymer Wofatit Y 77 we found a stronger adsorption on the carbons at smaller concentration whereas the resin has the larger capacity at higher concentration. Adsorbents were regenerated through hydrolysis of the pesticide at pH = 11.7. The velocity of hydrolysis in the adsorbed state is reduced to a tenth of that in solution. However, a transport resistance in the pores of adsorbents seems to be negligible as may be concluded from the very small measured particle diameter dependence of the velocity constants. In adsorption-regeneration measurements the capacity of the adsorbents stabilized at about 70% of that of the fresh adsorbents.  相似文献   

5.
The adsorption of Crypur-red BL, Crypur-yellow-brown and substances from spent lyes of the dyes Crypur-red GTL and Crypur-yellow-brown on silicate-rich adsorbents is investigated. The ZSM-type zeolites do not have any advantages as against alkali phyllosilicates and silica gel. The adsorbed quantities of dye are less than 10 mg dye/g adsorbent. In the low concentration range the adsorption isotherms correspond to the Langmuir equation. The treatment of spent lyes of dye results in a lowering of the COD-Mn by 90 %, at most.  相似文献   

6.
In the present study, the vine stem and modified vine stem were used as low cost adsorbents for the removal of acidic and basic dyes from aqueous solutions. A comparative study was also carried out with activated carbon obtained from vine stem and then the adsorption capacities of all adsorbents were evaluated by batch adsorption process. The effects of various adsorption parameters (initial pH, particle size, and contact time) were investigated. The modification of the vine stem with nitric acid increased its adsorption capacity for the basic dye. Both, vine stem and modified vine stem exhibited higher adsorption capacities than activated carbon. The adsorption capacities were found to be 322.58, 250, and 200 mg g?1 for modified, natural vine stem, and activated carbon, respectively. In the case of acidic dye, the pH strongly affected the adsorption capacity and the maximum dye uptake was observed at pH 2 for all adsorbents. The acidic dye adsorption was lower compared to basic dye on both biosorbents and activated carbon tested. The maximum acidic dye adsorption values (58.82 and 59.88 mg g?1) were obtained with the vine stem and activated carbon, respectively. In the case of lignocellulosic adsorbents, both surface charge and surface groups had main effect on the adsorption of basic dye, while adsorption mechanism in activated carbon was mainly through the physical adsorption. The results of comparative adsorption capacity of adsorbents indicated that vine stem or modified vine stem can be used as a low cost alternative to activated carbon in aqueous solution for basic dye removal.  相似文献   

7.
The separation of heavy metals by complexation with macromolecular water-soluble agents and subsequent ultrafiltration is described. The method can be expected to join common techniques of metal separation like liquid-liquid extraction, adsorption, redox reaction or liquid membrane permeation. Reactions between metal ions and polymer phases are characterized as pH-dependent distribution equilibria illustrated at a propene-maleic acid copolymer as an example. The complexation behaviour of the substance under study is governed by isotherms of the saturation type. Attempts proved to be successful to calculate break-through constants as well as saturation capacities from batch-type studies and dynamic measurements by transferring the laws of adsorption and ion exchange, respectively, to the ultrafiltration process. The quantities of fixed metals amounting to about 2.5 mmol/g were found to be in the range of moderate adsorbents. A solution consisting of 3 solutes has been tested to get more detailed information on mixture behaviour as compared to single component systems. In the long run, the proposed method should provide an additional variant for the extraction and concentration of metal ions from diluted aqueous solutions.  相似文献   

8.
The distribution patterns of rare earth elements(REEs) in fine-grained materials in various depositions were often found to be similar to those of the aeolian sediments deposited in the Loess Plateau in North China and the fine-grained materials were suggested to be derived from wind-blown dust.However,increasing evidence indicated that the REEs in the water-soluble portion of atmospheric depositions also displayed similar patterns to those of aeolian sediments.In this study,water-soluble REEs in three atmospheric depositions collected from different climatic zones in China were adsorbed with two adsorbents with distinct adsorption capacity,glass powder,and co-precipitated iron hydroxide.The results showed that the REEs adsorbed by the two adsorbents displayed patterns similar to those of the original atmospheric depositions.The typical characteristics of the REE patterns of atmospheric deposition can be well reproduced in the adsorbed REEs.The higher the REE concentrations in the atmospheric depositions,or the higher adsorption efficiency of the adsorbents,the better reproducibility of the REEs patterns.The results suggest that the REEs of the fine-grained materials in various sediments,which have a high adsorption capacity,especially those deposited in South China,may come from the water-soluble REEs in atmospheric deposition,and may not be appropriate tracers of wind-blown dust from North China.  相似文献   

9.
In this paper, a novel adsorbent developed by means of granulating of natural zeolite nanoparticles (i.e., clinoptilolite) was evaluated for possible removal of the petroleum monoaromatics (i.e., benzene, toluene, ethylbenzene, and xylene, BTEX). To do this, the natural zeolite was ground to produce nanosized particulate, then modified by two cationic surfactants and granulated. The effect of various parameters including temperature, initial pH of the solution, total dissolved solids (TDS), and concentration of a competitive substance (i.e., methyl tert‐butyl ether, MTBE) were studied and optimized using a Taguchi statistical approach. The results ascertained that initial pH of the solution was the most effective parameter. However, the low pH (acidic) was favorable for BTEX adsorption onto the developed adsorbents. In this study, the experimental parameters were optimized and the best adsorption condition by determination of effective factors was chosen. Based on the S/N ratio, the optimized conditions for BTEX removal were temperature of 40°C, initial pH of 3, TDS of 0 mg/L, and MTBE concentration of 100 µg/L. At the optimized conditions, the uptake of each BTEX compounds reached to more than 1.5 mg/g of adsorbents.  相似文献   

10.
As investigations on model solutions and real wastewaters with 30 … 33 g/l phenol and 5 … 10 g/l formaldehyde as well as pH = 2 … 3 have shown, the following technique of sewage purification proves to be optimal: condensation with addition of 7 g/l sulphuric acid at 98 °C, settling of the condensation products formed for 8 h, centrifugation of the supernatant and adsorption on activated carbon or a polymer sorbent (XAD 4). Preference should be given to activated carbon. The residual concentrations amount to 0.1 mg/l for both phenol and formaldehyde. The adsorbents are largely fully regenerated with methanol, the regeneration solution containing 11 … 20 g/l phenol.  相似文献   

11.
The present work involves the study of Se(IV) adsorption onto granular activated carbon (GAC) and powdered activated carbon (PAC). The adsorbents are coated with ferric chloride solution for the effective removal of selenium. The physico-chemical characterization of the adsorbents is carried out using standard methods, e. g., proximate analysis, scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), thermo-gravimetric (TGA) and differential thermal analysis (DTA), etc. The FTIR spectra of the GAC and PAC indicate the presence of various types of functional groups, e. g., free and hydrogen bonded OH groups, silanol groups (Si-OH), alkenes, and CO group stretching from aldehydes and ketones on the surface of adsorbents. Batch experiments are carried out to determine the effect of various factors such as adsorbent dose (w), initial pH, contact time (t), and temperature (T) on the adsorption process. The optimum GAC and PAC dosage is found to be 10 g/L and 8 g/L, respectively, for Se(IV) removal with C0 = 100 mg/L. The percent removal of Se(IV) increases with increasing adsorbent concentration, while removal per unit weight of adsorbent increases with decreasing adsorbent concentration. Se(IV) adsorption onto both the GAC and PAC adsorbents is high at low pH values, and decreases with increased initial pH. The results obtained are analyzed by various kinetic models. The parameters of pseudo-first order, pseudo-second order kinetics, and Weber-Morris intra particle kinetics are determined. It is seen that the sorption kinetics of Se(IV) onto GAC and PAC can be best represented by the pseudo-second order kinetic model.  相似文献   

12.
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   

13.
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   

14.
Of recent, adsorption process has gained a lot of attention as a cheap and effective means of removing trace metals from wastewater prior to discharge into water bodies. Being flexible in design and operation, the process has enabled an optimal recovery of trace metals such that the treated effluents meet the desired standards for waste disposal. Mercury is a toxicant released into the environment from natural and anthropogenic sources. It is notorious for having an unusual tendency to bio‐accumulate and persist in the food chain. Presence of mercury in food, especially those of aquatic sources has drastic implications on human health. Therefore, efforts have been made to develop and optimize low‐cost activated carbon (AC) as adsorbents for scavenging mercury from aqueous effluents. Herein, how mercury accumulates across the food chain, its health implications, and the recent advancement in the use of low‐cost ACs as adsorbent for trapping mercury from wastewater are highlighted. Relationship between the mercury removal efficiency and the surface morphology of the adsorbents as well as the influence of prevailing experimental condition on the sorption process were addressed. Challenges and future prospects of the use of low‐cost adsorbents in addressing mercury pollution in the environment are discussed.  相似文献   

15.
Low cost adsorbents were prepared from dried plants for the removal of heavy metals, nitrate, and phosphate ions from industrial wastewaters. The efficiency of these adsorbents was investigated using batch adsorption technique at room temperature. The dried plant particles were characterized by N2 at 77 K adsorption, scanning electron microscopy, energy dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy, and phytochemical screening. The adsorption experiments showed that the microparticles of the dried plants presented a good adsorption of heavy metals, phosphate, and nitrate ions from real wastewaters. This adsorption increased with increasing contact time. The equilibrium time was found to be 30 min for heavy metals and nitrate ions and 240 min for phosphate ions. After the adsorption process, the Pb(II) concentrations, as well as those of Cd(II), Cu(II), and Zn(II) were below the European drinking water norms concentrations. The percentage removal of heavy metals, nitrates, and phosphates from industrial wastewaters by dried plants was ～94% for Cd2+, ～92% for Cu2+, ～99% for Pb2+, ～97% for Zn2+, ～100% for ${\rm NO}_{{\rm 3}}^{{-} } $ and ～77% for ${\rm PO}_{{\rm 4}}^{3{-} } $ ions. It is proved that dried plants can be one alternative source for low cost absorbents to remove heavy metals, nitrate, and phosphate ions from municipal and industrial wastewaters.  相似文献   

16.
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   

17.
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   

18.
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   

19.
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   

20.
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   

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