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1.
Removal of organic pollutants from aqueous solutions by adsorbents prepared from an agroalimentary by-product 总被引:1,自引:0,他引:1
Two series of crosslinked starch polymers were tested for their ability to adsorb organic pollutants in aqueous solutions. The polymers were prepared by a crosslinking reaction of starch-enriched flour using epichlorohydrin as the crosslinking agent, without and in the presence of NH(4)OH. These polymers were used as sorbent materials for the removal of phenolic derivatives from wastewater. The influence of several parameters (kinetics, pH and polymer structure) on the sorption capacity was evaluated using the batch and the open column methods. Results of adsorption experiments showed that the starch-based materials exhibited high sorption capacities toward phenolic derivatives. The study of the kinetics of pollutant uptake revealed that the adsorbents presented a relatively fast rate of adsorption. The experimental data were examined using the Langmuir and Freundlich models and it was found that the Freundlich model appeared to fit the isotherm data better than the Langmuir model. 相似文献
2.
Many polluted sites are simultaneously contaminated with polycyclic aromatic hydrocarbons and heavy metals. In the present study, batch and continuous column experiments were performed utilizing self-composition soil to describe the sorption behavior of two contaminants: lead (Pb2+) and pyrene (PYR). Operational conditions such as contact time, bed depth, and flow rate were optimized. The effect of soil organic matter content on the process of adsorption of both contaminants was investigated. The presence of PYR in solution at neutral pH (6.0–7.5) decreased Pb2+ sorption. Similar behavior was observed for PYR in the presence of Pb2+ in solution. At room temperature, batch experimental data conducted as a function of contact time were analyzed using the Langmuir and Freundlich isotherms. Results revealed that Pb2+ sorption isotherms were fitted better by the Langmuir model and PYR sorption isotherms were fitted better by the Freundlich model. Column adsorption experiments were carried out at room temperature and under operating parameters (bed depth, flow rate, and initial contaminant concentration). Breakthrough curves were well fitted to the two-site first-order kinetic model with a sum of square errors less than 0.14. The Pb2+ adsorption kinetic data were processed also for the Thomas model with a good accuracy. 相似文献
3.
Dalibor Broznić Jelena Marinić Marin Tota Gordana Čanadi Jurešić Orjen Petković Čedomila Milin 《Soil & Sediment Contamination》2012,21(7):850-871
Sorption and desorption are important processes that influence the transport, transformation, and bioavailability of imidacloprid in the soils. Equilibrium batch experiments were carried out using six coastal Croatian soils. The equilibrium sorption and desorption experimental data showed the best fit to the Freundlich equation. Sorption parameters predicted with the Freundlich model, KF sor and 1/n ranged from 2.92 to 5.74 (mg/kg)/(mg/L)1/n, and 0.888 to 0.919, respectively. The sorption of imidacloprid was found to be sensitive to organic carbon (OC) content. The highest sorption was observed in Krk soil (OC 4.74%) and the lowest in Zadar soil (OC 1.06%). Fitted desorption parameter values, KF des , were consistently higher than those associated with sorption. The opposite trend was observed for the exponential parameter 1/n. Results also suggested that imidacloprid sorption-desorption by soil is concentration-dependent, i.e. at lower imidacloprid concentrations a greater sorption percentage and lower desorption percentage occurred. Desorption studies revealed that there was a hysteresis effect in all the tested soils. Hysteresis coefficient values (H) varied from 0.656 to 0.859. The study results emphasize that the controlled application of imidacloprid is obligatory, especially in soils with a low organic carbon content, in order to minimize a risk of environmental and groundwater pollution. 相似文献
4.
In this study, the sorption of methylene blue, a basic dye, onto tamarind fruit shell was studied by performing batch kinetic sorption experiments. The equilibrium kinetic data were analyzed using the pseudo-second-order kinetic model. A comparison between linear least squares method and nonlinear regression method of estimating the kinetic parameters was examined. Four pseudo-second-order kinetic linear equations were discussed. The coefficient of determination (r 2), and the chi-square (χ2) test were employed as error analysis methods to determine the best-fitting equation. Kinetic parameters obtained from four kinetic linear equations using the linear method differed but they were the same when nonlinear method was used. Present investigation showed that by linear method a Type 1 expression very well represent the kinetic uptake of methylene blue onto tamarind fruit shell. Linear method was found to check only the hypothesis instead of verifying the kinetic model. Nonlinear regression method was found to be the more appropriate method to determine the rate kinetic parameters. 相似文献
5.
Muhammad Abid Irshad Bibi Abida Farooqi Yong Sik Ok Anitha Kunhikrishnan 《International journal of phytoremediation》2016,18(5):442-449
Biosorption efficiency of natural orange peel (NOP) and charred orange peel (COP) was examined for the immobilization of arsenate (As(V)) in aqueous environments using batch sorption experiments. Sorption experiments were carried out as a function of pH, time, initial As(V) concentration and biosorbent dose, using NOP and COP (pretreated with sulfuric acid). Arsenate sorption was found to be maximum at pH 6.5, with higher As(V) removal percentage (98%) by COP than NOP (68%) at 4 g L?1 optimum biosorbent dose. Sorption isotherm data exhibited a higher As(V) sorption (60.9 mg g?1) for COP than NOP (32.7 mg g?1). Langmuir model provided the best fit to describe As(V) sorption. Fourier transform infrared spectroscopy and scanning electron microscopy combined with energy dispersive X-ray spectroscopy analyses revealed that the –OH, –COOH, and –N-H surface functional groups were involved in As(V) biosorption and the meso- to micro-porous structure of COP sequestered significantly (2-times) higher As(V) than NOP, respectively. Arsenate desorption from COP was found to be lower (10%) than NOP (26%) up to the third regeneration cycle. The results highlight that this method has a great potential to produce unique ‘charred’ materials from the widely available biowastes, with enhanced As(V) sorption properties. 相似文献
6.
《Process Biochemistry》2007,42(1):16-24
The kinetics and mechanism of the sorptive removal of methylene blue dye from aqueous solution using palm kernel fibre as adsorbent have been investigated. Batch kinetic experiments were performed and system variables investigated includes pH and initial dye concentration. The kinetic data were fitted to the pseudo-first, pseudo-second, intraparticle diffusion and mass transfer models. The pseudo-first order reaction kinetics fitted to the experimental data only in the first 5 min of sorption and then deviated, while the pseudo-second order kinetic model was found to fit the experimental data for the entire sorption period with high coefficient of determination. Equations were developed using the pseudo-second order model, which predicts the amounts of methylene blue at any contact time and initial concentration within the given range. This suggests that the sorption of methylene blue onto palm kernel fibre follows a chemical activation mechanism. A mathematical relationship was also drawn between the equilibrium sorption capacity and the change in pH (ΔH+) at the end of the kinetic experiments with varying initial dye concentration, supporting the fact that chemical reaction (ion exchange) occurred and is important in the rate determining step. Mass transfer was found to be favoured at high concentrations while intraparticle diffusion was favoured at low concentrations. 相似文献
7.
Gloria Teijón Lucila Candela Jirka Šimůnek Karim Tamoh Javier Valdes-Abellán 《Soil & Sediment Contamination》2014,23(7):736-750
Naproxen-C14H14O3 is a nonsteroidal anti-inflammatory drug which has been found at detectable concentrations in wastewater, surface water, and groundwater. Naproxen is relatively hydrophilic and is in anionic form at pH between 6 and 8. In this study, column experiments were performed using an unconsolidated aquifer material from an area near Barcelona (Spain) to assess transport and reaction mechanisms of Naproxen in the aquifer matrix under different pore water fluxes. Results were evaluated using HYDRUS-1D, which was used to estimate transport parameters. Batch sorption isotherms for Naproxen conformed with the linear model with a sorption coefficient of 0.42 (cm3 g?1), suggesting a low sorption affinity. Naproxen breakthrough curves (BTCs) measured in soil columns under steady-state, saturated water flow conditions displayed similar behavior, with no apparent hysteresis in sorption or dependence of retardation (R, 3.85-4.24) on pore water velocities. Soil sorption did not show any significant decrease for increasing flow rates, as observed from Naproxen recovery in the effluent. Sorption parameters estimated by the model suggest that Naproxen has a low sorption affinity to aquifer matrix. Most sorption of Naproxen occurred on the instantaneous sorption sites, with the kinetic sorption sites representing only about 10 to 40% of total sorption. 相似文献
8.
To fulfill the purpose as a sink for trace elements, soils must not be overloaded with As and Cd. Therefore, it is necessary
to get knowledge of the sorption capacities of soils on a regional scale. The determination of these sorption capacities for
large areas is, however, impeded by the great expenditure of laboratory work involved. With data presented here retention
capacities for cadmium and arsenic from routinely determined soil parameters are estimated. In batch experiments the sorption
behaviour of 40 soils from the area of Freiberg/Saxony in Germany was examined. The obtained sorption isotherms from the laboratory
were fitted to the Freundlich equation (S = k*Cm). The two constants (k, m) of this equation were used for multiple linear regression to correlate the sorption capacity and
the soil parameters, namely clay content, pH value, total organic carbon, and dithionite extractable Fe contents. Due to long
lasting ore mining of Freiberg there exist high background levels in that area for the two surveyed elements As and Cd. Therefore,
this study offers two different mathematical procedures to take these contaminations into account. Thus the experimental data
were corrected before they were fitted to Freundlich and pedotransfer equations were determined. Using the transfer equation,
parameter k and m for cadmium sorption could be estimated with statistical certainties of 91% and 61% (adjusted R2), respectively, whereas the predictability for the arsenic sorption is not practicable because achieved R2 values are very low (17% and 7%).
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
9.
Yingxue Li Yidong Guan Kewei Yu Wenhua Wang 《International journal of phytoremediation》2019,21(2):145-151
Four biochars were made via pyrolysis at 500?°C using different waste plant materials, including tree branches from Cinnamonum campora (L.) Pres (CCP), Eriobotrya japonica (Thunb.) Lindl (EJL), Rohdea roth (RR) and bamboo shoots (Phyllostachys sulphurea) (PS). Phosphorus sorption capacities of the biochars were studied by isothermal experiments on their sorption kinetics. Results show that P sorption to the three wood biochars (CCP, EJL, and RR) fitted well with Lagergren pseudo second order model. However, P release was found in the PS biochar and sand amended with the PS biochar treatments during the isothermal sorption experiment. Phosphorus sorption capacity of the CCP biochar, EJL biochar and RR biochar was 4,762.0, 2, 439.0 and 1, 639.3?mg/kg, respectively. The CCP biochar showed the highest P sorption capacity due to its higher pH, lower dissolved P content, larger surface area (23.067 m2/g) and pore volume (0.058?cm3/g). The PS biochar showed the lowest P sorption due to its higher dissolved P content, more carboxyl groups, and smaller surface area (2.982 m2/g) and pore volume (0.017?cm3/g). Results suggest that the CCP biochar could be a potential alternative adsorbent for P sorption, such as removing P in wastewater treatment by constructed wetlands. 相似文献
10.
The purpose of this investigation was to determine the mechanism of interaction between ketotifen fumarate and chitosan at
different pH values. The specific surface area of chitosan was determined using gas sorption analyzer. The sorption experiments
were conducted at pH 7 and 10 using two different particle size ranges of chitosan. The solutions were prepared at constant
ionic strength and buffer concentration, with only varying the pH. The rotating bottle method was used for measuring the sorption.
The average specific surface areas for the two different particle size ranges of chitosan were found to be 4.56 and 0.74 m2/g. The Langmuir-like equation and a model independent equation were both applied to the sorption experimental data. The extent
of ketotifen uptake at pH 7 for small and large particles of chitosan was found to be 1,073 and 2,204 mg/g respectively. While
the extent of ketotifen uptake at pH 10 for small and large particles of chitosan was found to be 4 and 11 mg/g respectively.
The aforementioned results indicated that sorption of ketotifen fumarate at pH 7 is extremely high compared to pH 10 and that
the sorption increases by decreasing the specific surface area of chitosan. Based on the results obtained, the following conclusions
were reached. Ketotifen might be absorbed into the bulk structure of chitosan in addition to being adsorbed on the surface
and the ability of chitosan to swell at pH 7 has a significant role in increasing its uptake. 相似文献
11.
《Chemical Speciation and Bioavailability》2013,25(4):249-260
AbstractA series of batch adsorption experiments were carried out, with the aim of removing cadmium ions from aqueous solutions and water samples using powdered marble wastes (PMW) as an effective inorganic sorbent. PMW is inexpensive, widespread, and may be considered as environmental problem. The main parameters (i.e. solution pH, sorbent and cadmium concentrations, stirring time, and temperature) influencing the sorption process were investigated. The results obtained for sorption of cadmium ions onto PMW are well described by the Freundlich and Langmuir models. The Dubinin-Radushkevick (D–R) isotherm model was applied to describe the nature of the adsorption of the metal ion; it was found that the adsorption process was chemical in nature. The thermodynamic parameters were also calculated from the Gibbs free energy change (ΔG°), enthalpy (AH°) and entropy (ΔS°). These parameters indicated that the adsorption process of cadmium(II) ions on PMW was spontaneous and endothermic in nature. Under the optimum experimental conditions employed the removal of ca ~100% of Cd2+ ions was attained. The procedure was successfully applied to removal of the cadmium ions from aqueous and various natural water samples. The adsorption mechanism is discussed. 相似文献
12.
Matthias Suhr Nancy Unger Karen E. Viacava Tobias J. Günther Johannes Raff Katrin Pollmann 《Biometals》2014,27(6):1337-1349
Surface layer proteins (S-layer) of Lysinibacillus sphaericus JG-B53 are biological compounds with several bio-based technical applications such as biosorptive materials for metal removal or rare metals recovery from the environment. Despite their well-described applications, a deeper understanding of their metal sorption behavior still remains challenging. The metal sorption ability of Au3+, Pd2+, Pt2+ and Eu3+ was investigated by ICP-MS, AFM and QCM-D which enables the sorption detection in real-time during in situ experiments. Results indicate a high binding of Pd, followed by Au, Eu and Pt to the proteins. The comparison between different methods allowed a deeper understanding of the metal sorption of isolated S-layer either frees in liquid, adsorbed forming a protein layer or as the bacteria surface. 相似文献
13.
Moisture sorption isotherms for oat flour and rice flour were determined at 5, 23, and 45 °C using a gravimetric technique
in an a
w range of 0.08–0.98. The results obtained showed that, for a
w values lower than around 0.75, in both flours, the sorption capacity decreased with increasing temperature, while the opposite
behavior was observed at a
w greater than this value. It was found that the experimental data in the water activity range considered were better represented
by the four-parameter Peleg equation. The monolayer water contents for both materials were determined by the BET and GAB models.
The net isosteric heats of sorption were estimated using the Clausius–Clapeyron equation. For both materials, the monolayer
water content and the isosteric heat of sorption were found to decrease with increasing temperature and increasing moisture
content, respectively. 相似文献
14.
Chemical equilibrium modeling of copper precipitation in a hyper-concentrated solid-liquid system 总被引:1,自引:0,他引:1
Rapid progress has been made recently in the understanding of heavy metal sorption and speciation on sediment and soils. One aspect that was overlooked in the previous studies was the process of pollutant transformation and transportation in hyper-concentrated solid-liquid systems. In this paper, batch experiments on copper sorption in association with loess at high sediment concentrations were conducted. However, some reaction mechanisms were difficult to determine experimentally due to the limitations of speciation extraction methods. In an additional study, the MINTEQA2 chemical equilibrium model was used to calculate the speciation and precipitation of copper sorption by loess to give quantitative predictions and detailed information about the reaction process. The experiments and the modeling simulation were made under the same sorption conditions, with sediment concentrations ranging from 50 to 200 kg/m3 and adsorbates of CuSO4 and Cu(NO3)2, in order to compare their results. The modeling results clearly supported the experimental results, fully explained the mechanisms of the effects of chemical form and sediment concentration on the copper sorption, and strengthened the dominant role of carbonates among the main components of loess in the process of copper sorption. 相似文献
15.
《Ecological Engineering》2007,29(2):200-208
Filtralite P® and shellsand as ideal constructed wetland substrates have been tested for their P sorption capacity, both with batch and column experiments. Two columns were filled with Filtralite P® and one column with shellsand. The shellsand (SSPS) and one of the Filtralite P® columns (FLSP) were loaded with a synthetic P solution, while the second Filtralite P® column (FLWW) was loaded with secondary wastewater. Ca, Mg, pH, and the P concentrations were measured in the inlet and the seven outlets along the height of the three vertical upflow columns for up to 303 days. An overall P removal rate of 92, 91, and 54% was measured in the columns SSPS, FLWW, and FLPS, respectively, for the entire experimental period. The comparison of FLWW and FLPS showed that FLWW kept its high P removal efficiency (91%) throughout the experimental period while the removal efficiency of FLPS decreased fast after reaching the 1 ppm effluent P concentration. The competition of other negative ions and the development of biofilm did not have a negative effect on P removal from wastewater. The batch experiments showed a better sorption capacity of Filtralite P® at low initial concentrations, while for high initial concentrations the shellsand sorbed more. Shellsand had, however, a higher sorption capacity in batch experiments with used column material and high initial P concentrations. The results from both the batch and the column experiment suggest that the shellsand has a more durable P sorption capacity than the Filtralite P® material, possibly due to the persistent high concentrations of Ca in the shellsand. 相似文献
16.
Carica papaya, a novel sorbent, was evaluated for sorption of Hg(II) from synthetic aqueous solutions using various pseudo-second order kinetic models as well as equilibrium sorption models. Batch kinetic and equilibrium experiments were carried out for the sorption of Hg(II) onto C. papaya at pH 6.5 and solid to liquid ratio (s/l) 1.0 g L?1. The kinetic data were fitted to second order models of Sobkowsk and Czerwinski, Ritchie, Blanchard, Ho and McKay, whereas Langmuir, Freundlich, and Redlich-Peterson models were used for the equilibrium data. A comparative study on both linear and nonlinear regression showed that the Sobkowsk and Czerwinski and Ritchie's second order model were the same. Ho and McKay's pseudo-second order model fitted well to the experimental data when compared with the other second order kinetic expressions. Langmuir isotherm parameters obtained from the four Langmuir linear equations by using linear method were dissimilar, but were the same when nonlinear method was used. Additionally, various thermodynamic parameters, such as ΔG 0, ΔH 0, and ΔS 0, were calculated. The negative values of Gibbs free energy (ΔG 0) and ΔH 0 confirmed the intrinsic nature of biosorption process and exothermic, respectively. The negative value of ΔS 0 showed the decreased randomness at the solid-solution interface during biosorption. 相似文献
17.
The novel biosorbent silk cotton hull, an agrowaste material, has been successfully utilized for the removal of cadmium(II) from aqueous solutions. The adsorption of cadmium onto three kinds of activated biosorbent has been studied: modified by concentrated sulfuric acid alone (AC), a mixture of concentrated sulfuric acid and hydrogen peroxide (AC1), and a mixture of concentrated sulfuric acid and ammonium persulfate (AC2). The adsorption studies were carried out to optimize the process parameters such as pH, adsorbent dosage, contact time, and initial metal ion concentration. Maximum metal removal was observed at pH 7.0 with a contact time of 90 min at stirring speed of 200 rpm with an adsorbent dosage of 4.0 g L?1. The sorption isotherms were studied using the Langmuir, Freundlich, and Tempkin isotherm models. The maximum adsorption capacities were 100.00, 142.86, and 142.87 mg g?1 for AC, AC1, and AC2, respectively. Accordingly, the surface modification of the activated carbons AC1 and AC2 enhanced cadmium removal greatly. The experiments demonstrated that the removal of metal ions followed the pseudo-second-order kinetic model. The sorption mechanism is discussed in terms of the activated surface properties. A relationship between the oxygen content and sorption was found in this novel material. Desorption experiments were carried out using hydrochloric acid with a view to generate the spent adsorbent and to recover the adsorbed metal ions. 相似文献
18.
Saima Nasreen Uzaira Rafique Sheryl Ehrman Muhammad Aqeel Ashraf 《Saudi Journal of Biological Sciences》2019,26(6):1161-1170
Water pollution due to organic compounds is of great concern and efforts are being made to develop efficient adsorbents for remediation of toxic pollutants. The development of new functionalized materials with increased performance is growing to meet the regulatory standards in response to public concerns for environment. In this study, an attempt has been made to investigate the influence of synthesis parameters like the reaction temperature, the surfactant-to-silica ratio and reaction time on the structural and textural properties of novel ordered mesoporous silica hybrids. In order to understand the effect of different synthesis parameters, all the prepared materials were systematically characterized by various analytical, spectroscopic and imaging techniques such as XRD, BET, TG etc. It was deduced from these studies that the synthesis temperature influence greatly the structural order whereas both the P104/Na2SiO3 molar ratio and reaction time found to influence textural properties significantly. However, under optimized experimental condition, we could achieve the functionalized silica hybrids that offers successful incorporation of -Amino, -Glucidoxy, -Methacrylate, -Vinyl and -Phenyl moieties indicated by FTIR peaks at 793 cm?1, 2870 cm?1, 796 cm?1, 1630 cm?1 and 954 cm?1. XRD studies reveal orthorhombic and tetragonal symmetry for the hybrids and these materials were found to be thermally stable due to incorporation of organic moiety in silica matrix. Functionalized silica hybrids then applied as adsorbents demonstrated efficient and comparable removal of 4-aminophenol and p-nitrophenol in 20 min facilitated through organic moiety. Detailed modeling of the sorption using equilibrium and kinetic isotherms has been carried out to get an insight into the transport process. The adsorption isotherms of phenol derivatives are well-fitted with the Langmuir, Freundlich and Temkin Isotherms and the adsorption kinetics follows the pseudo second order model. The modeling confirms that the uptake is a chemisorption process. 相似文献
19.
《Process Biochemistry》2004,39(6):761-765
The kinetics of cadmium sorption on to tree fern has been investigated based on the assumption of a pseudo-second order rate law. The batch sorption model has been applied to predict the rate constant of sorption and the equilibrium capacity with the effect of initial cadmium concentration. The experimental results have been analysed by pseudo-Langmuir, pseudo-Freundlich and pseudo-Redlich–Peterson isotherms based on pseudo-second order kinetic expression constant. Both pseudo-Langmuir and pseudo-Redlich–Peterson isotherms were found to represent the measured sorption data well. According to the evaluation using the pseudo-Langmuir equation, the monolayer sorption capacity was obtained to he 16.3 mg/g. In addition, χ2 analysis was also used to determine the most suitable model. Pseudo-Langmuir and pseudo-Redlich–Peterson were also the best models for the experiment data from χ2 analysis. 相似文献
20.
Lin Guan James N. Petersen Donald L. Johnstone David R. Yonge Thomas M. Brouns 《Biotechnology letters》1993,15(7):733-736
Summary A fractional factorial statistical experimental design was used to ascertain which experimental parameters affect the rate at which Cr6+ is sorbed by a consortium of denitrifying bacteria. Data from this set of experiments indicates that the amount of chromium sorbed as a function of time could be described by an exponential rise function. Additionally, the data indicate that at least 15 hours were required to establish equilibrium. Finally, observed variations in the parameters in this rate equation were found to be due to the imposed changes in the experimental variables. These results indicate that the processes by which the chromate ion was removed from solution may be associated with the cells' metabolic processes. 相似文献