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Rapid Removal of Aniline from Contaminated Water by a Novel Polymeric Adsorbent
Abstract
Dummy molecularly imprinted polymers (DMIPs) for aniline were synthesized by a thermal polymerization method using acrylamide as a functional monomer, ethylene dimethacrylate as a crosslinker, 2,2-azobisisobutyronitrile as a free radical initiator, acetonitrile as a porogenic solvent, and analogues of aniline, namely sulfadiazine, as the template. The DMIPs that were obtained showed a high affinity to aniline compared to non-imprinted polymers. It was proven that the DMIPs obtained using sulfadiazine as the template were much better than the molecularly imprinted polymers using aniline as the template. The results indicated that the Freundlich model was fit for the adsorption model of DMIP for aniline and the adsorption model of the DMIP for aniline was multilayer adsorption. Furthermore, the results showed that the DMIP synthesized by bulk polymerization could be used as a novel adsorbent for removal of aniline from contaminated water.
... Aniline is a highly toxic substance and can cause serious environmental pollution if discharged without proper treatment. Due to its high solubility in water, aniline can easily permeate through soil and contaminates groundwater, leading to its presence in the environment at certain concentrations [2][3][4]. Aniline is known to be carcinogenic, teratogenic and mutagenic. It can enter the human body through inhalation, ingestion, or skin contact, causing tissue hypoxia and damage to the central nervous system, cardiovascular system and other organs [5,6]. ...
Aniline is an important chemical raw material that is highly toxic and can cause serious pollution to the environment if discharged without effective treatment. In this study, headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry was found to be effective in extracting aniline from soil and sediment samples. An HP-INNOWAX polar column, 85 μm CAR-PDMS fiber head, pure water solution with pH of 12, an extraction temperature of 75°C, an extraction time of 55 min, an extraction speed of 20 mm/s, and a resolution time of 3 min was selected. The method exhibited good linear in the range of 0–250 ng, with a relative standard deviation of the relative response factor of 3.9%. The blank spiked recoveries of aniline ranged from 110% to 116% with a relative standard deviation of 2.09%. The spiked recoveries of soil and sediment ranged from 81.4% to 92.0% and 92.2% to 109% respectively, with detection limits of 1.5 μg/kg. The method is simple, practical, accurate and reliable, and can be used for the determination of aniline in soil and sediment.
... Aniline is a widely used industrial chemical, but it is also one of the recognized contaminants which can badly pollute water and soil. So, intensive study on controlling and removing the aniline-induced pollution is of great importance [10,11]. Due to its high chemical stability, aniline is hardly degraded by some conventional approaches. ...
The photooxidation process of aniline-containing simulated wastewater under visible light irradiation over BiOBr microcrystal grains with different shapes was studied. The distinctive surface microstructures of the BiOBr microcrystals, like clustered flower petals and quadrate lamellas, were produced by using imidazole ionic liquid and inorganic bromide as Br sources and by solvothermal and hydrothermal route, respectively. The ionic liquid not only can impact the products’ morphology, but also can largely improve the photocatalytic activity of the BiOBr microcrystals due to the soft templating effect. The top degradation ratio of the aniline wastewater photocatalyzed by lamellar BiOBr crystals is 23.71%, but the equivalent value photocatalyzed by flower petal-like BiOBr crystals is almost twice as much; that is, it reaches 46.51%. The photodegradation effect and mechanism over differently shaped BiOBr microcrystals have been compared.
Polymers of Intrinsic Microporosity (PIMs) are documented as suitable materials for organic adsorption applications. Intrinsic porous structure along with a solution-processability behaviour make them attractive for the adsorption of organic contaminants from water. In this research, PIM-2 powder was synthesised and the exploitation of PIM-2 for aniline removal was studied using a batch adsorption process. The effect of several variables were explored including initial aniline concentration, adsorption time and temperature. Adsorption reached the equilibrium after five hours and experimental adsorption capacity (qe, exp) was found as 79.7 mg g-1 for aniline at pH 6 and 298K. Isotherm (Langmuir, Freundlich and Liu) and kinetic models (pseudo first order and pseudo second order) and elovich model were applied using non-linear regression analysis. In addition, various errors analysis approaches were used to determine the most appropriate isotherm and kinetic models. Pseudo second order model and Liu isotherm fitted well for aniline adsorption. Maximum adsorption capacity (qm) were computed as 82.4 mg g-1 for aniline at pH 6 and 298 K based on the Liu adsorption model. Thermodynamic studies revealed that the adsorption process was physical, spontaneous and exothermic.
Th e polymerization of monomers in the presence of a target molecule that imprints structural
information into resulting network polymers, called molecularly imprinted polymer (MIP), is a
scientifi c fi eld that is rapidly gaining signifi cance for a wide range of applications in chemistry,
biotechnology and pharmaceutical research. Due to their analytically useful properties, such
as selectivity, shelf stability, robustness and reusability, MIP off ers potential for the synthesis of
artifi cial recognition material and they are being proposed for the development of novel biorecognition
techniques for human health and bioterrorism protection technologies. MIPs are
successfully applied for developing and applying the analytical protocol/technology for selective
and specifi c determination of a wide range of pharmaceutics in various matrices. Th e proposed
chapter deals with all aspects of application of this technology (MIP) for analytical determination
of pharmaceutical samples.
M aleic anhydride-heptene-1-styrene terpolymer has been synthesized and modified with allyl alcohol and methylmethacrylate in order to prepare a new cross-linked functional polymer sorbent. The synthesized terpolymer, mono-allyl ester of terpolymer and synthesized cross-linked sorbent were characterized by Fourier transform infrared and 1 H NMR spectroscopies. The synthesized cross-linked polymer sorbent has a network structure and contains carboxylic acid, carbonyl and ester groups, all of which are capable of interacting with metal ions. The sorption performance of uranyl ions under optimum sorption conditions was evaluated. The analytical characteristics of the sorbent, such as, the solution pH, sorption degree and sorption capacity, have been established and the optimum sorption conditions have been determined. The sorption degree reaches a maximum at pH 6 (73.5%) and the maximum experimental sorption capacity of the sorbent for uranyl ions has been estimated as 1.8 mmol.g -1 (486 mg.g -1). Sorption isotherms of uranyl ions onto prepared polymer sorbent have been measured and the equilibrium data have fitted well to the Langmuir and Freundlich isotherm models. Langmuir and Freundlich isotherm constants and correlation coefficients for the present system are calculated and compared. The obtained values of the Langmuir and Freundlich equations parameters (q max = 2.03 mmol.g -1 , K L = 2.56, K F = 1.33, n = 2.35) specify a sufficient-ly high sorption activity of the synthesized sorbent towards uranyl ions. Uranyl ions are desorbed from the sorbent by treatment with 20-25% hydrochloric and nitric acids.
Biosorption potential of dried Neurospora crassa for Burazol Blue ED was studied with respect to pH, equilibrium time, biomass concentration and temperature to determine equilibrium and kinetic model parameters. The most suitable pH, equilibrium time and biomass concentration were determined as 1±0.2, 60min and 1.6g L−1, respectively, at 20°C±1.0. The equilibrium data was best described by the Langmuir isotherm model. The maximum biosorption capacity (qm) of biomass obtained from the Langmuir fit was 110.1mg g−1 biomass at 30°C. The overall biosorption process was best described by the pseudo-second-order kinetic model. The biosorption process was found to be favored at higher temperatures.
The conditions for preparation of activated carbon from walnut (Carya cathayensis S.) shell were studied with phosphate method, and optimized with orthogonal experiments taking phosphate concentration, carbonizing temperature and time as influential factors, methylene blue adsorption, iodine value and yield as indexes, and the adsorption process was analyzed in thermodynamics. The results showed that the adsorption value of the activated carbon to methylene blue was 102 mL/g, the iodine value 804.36 mg/g, and the yield 53.21%, which was produced at the conditions of 300°C activation temperature, 45 min activation time and phosphate concentration 50%(ω). In the studied conditions, the adsorption increased with increasing of temperature, acidic condition was beneficial to the adsorption. The equilibrium data fit well with Freundlich isotherm, and the thermodynamic parameters indicated that the adsorption reaction was exothermic and spontaneous.
Some random three-component copolymers have been prepared by condensing of formaldehyde with various aromatic amines. The compositions of the copolymers have been determined by known methods. Selective complexation of copolymers have been carried out with PAA, PEI, PVP and some transition metal ions (e.g., Cu2+) by adding the components in various sequences. The relative complexation ability of different -NH2 groups, associated with the various comonomer units, has been interpreted in terms of the nature of substituents present at the para position of the comonomer units. The formation of these complexes has been studied by conductometry, potentiometry and viscometry techniques. A scheme has been presented to explain the mode of interaction of the various components.
The use of powdered activated carbon treatment (PACT), based on simultaneous adsorption and biodegradation, is effective for treating organic toxic pollutants, present in industrial wastewaters. Removal of phenol and aniline from aqueous solutions by biological treatment alone, by adsorption on powdered activated carbon (PAC) alone and by simultaneous adsorption and biodegradation were compared. In the adsorption experiments, Langmuir adsorption isotherms were obtained, from which Qo, the limiting adsorption capacities, and b, the constant related to the energy of adsorption, were determined. Qo values of phenol and aniline were found to be similar, while the energy-related constant for aniline was five times higher than for phenol. Addition of mineral nutrients, needed for the biological treatment, and inactivated microbial cells increased the limiting adsorption capacities and significantly decreased the energy related constants. In biological treatment alone, kinetic studies showed that aniline was more resistant to biodegradation than phenol. In the simultaneous adsorption and biodegradation process, the PAC presence differently affected the biooxidation of phenol and aniline. While the PAC enhanced the microbial respiration in the phenol bioreactor, it significantly reduced the microbial respiration in the aniline bioreactor. Different organic removal mechanisms are suggested in PACT for phenol and aniline, due to their different energy of adsorption. The respirometric studies are recommended as an adequate tool for prediction of toxic organics removal capabilities from industrial wastewaters by PACT.
In this investigation, nine typical compounds, i.e., phenol, 2-aminophenol, aniline, 2-chlorophenol, chlorobenzene, ß-naphthol, naphthalene, α-naphthylamine and α-chloronaphthalene were introduced to evaluate the effects of the molecular structure and physicochemical properties of these selected adsorbates on the adsorption capacity and desorption efficiency of the activated carbon. Both the thermal and chemical regeneration methods were employed to compare the regeneration efficiencies among these adsorbates and adsorbent.
A molecularly imprinted polymer which recognises the mycotoxin ochratoxin A was prepared using the mimic N-(4-chloro-1-hydroxy-2-naphthoylamido)-(L) -phenylalanine as a template. The polymer was obtained by dissolving the template, methacrylic acid and ethylendimethacrylate in chloroform and polymerising the mixture by thermal treatment at 60 °C. The monolith obtained was crushed, sieved to 30–90 μm and extensively washed till the template could no longer be found in the washing solution. The binding properties towards the template, ochratoxin A and several related molecules were measured by eluting with acetonitrile and chloroform a HPLC column packed with the imprinted polymer. The experimental results show that the polymer recognises not only the template well, but also the ochratoxin A. The specific molecular recognition effect is due to hydrogen bond interactions but in order to assure the full recognition effect adjunctive steric factors are necessary. The magnitude of these interactions can be controlled by the use of limited amounts of acetic acid in the mobile phase.
From the measurement of the relative selectivity it was found that only the simultaneous presence of the carboxyl, the phenolic hydroxyl and certain peculiar substructures such as the chlorine atom assures the whole recognition of the template.
A molecularly imprinted polymer (MIP)-based optode has been developed for zearalenone (ZON) mycotoxin analysis. The automated flow-through assay is based on the displacement of tailor-made highly fluorescent tracers by the analyte from a MIP prepared by UV irradiation of a mixture of cyclododecyl 2,4-dihydroxybenzoate (template, ZON mimic), 1-allyl piperazine (functional monomer), trimethylolpropane trimethacrylate (crosslinker) and 2,2′-azobisisobutyronitrile in acetonitrile (porogen). Three fluorescent analogues of ZON, namely 2,4-dihydroxybenzoic acid 2-[methyl(7-nitro-benzo[1,2,5]oxadiazol-4-yl)amino]ethyl ester (NBDRA), 2,4-dihydroxy-N-pyren-1-ylmethylbenzamide (PMRA) and of 2,4-dihydroxybenzoic acid 2-[(pyrene-l-carbonyl)amino] ethyl ester (PARA), have been molecularly engineered for the assay development. The pyrene-containing tracers also inform on the characteristics of the microenvironment of the MIP binding sites. PARA has been finally selected to optimize the ZON displacement fluorosensor, that shows a limit of detection of 2.5 × 10−5 M in acetonitrile. A positive cross-reactivity has been found for β-zearalenol, but not for resorcinol, resorcylic acid, 17β-estradiol, estrone or bisphenol-A.
Efficiency of acid–base treated raw laterite (RL) is investigated for removal of fluoride. FTIR, SEM-EDX, and surface area analyzer are used to characterize the treated laterite (TL). The batch adsorption of fluoride is explored using TL under varying process conditions like adsorbent dose, pH of solution, temperature, particle size and contact time. The adsorption isotherm data of fluoride ions on TL are fitted well to both Langmuir and Freundlich models. The temperature dependent maximum Langmuir adsorption capacities of fluoride ion on TL are found to be 36.3, 37.9, and 39.1 mg/g at 288, 305, and 315 K, respectively. A simple shrinking core model is applied to predict the batch adsorption kinetics of fluoride ions onto treated laterite (TL). In the proposed two-resistance model, external mass transfer (Kf) and pore diffusion coefficient (De) are estimated by comparing the simulated concentration profile with the experimental data using a non-linear optimization technique. Estimated values of De and Kf are found to be 4.8 × 10−10 m2/s and 8.5 × 10−4 m/s at 305 K, respectively. The fluoride adsorption in presence of other competitive ions as well as desorption of fluoride ions from spent adsorbent are studied in detail.
The sorption of aromatic amines as ligands on polymer-bound ferrous ion has been measured, using the sulfonic polystyrene resin Dowex 50W-X8 to bind the Fe2+ ion. The sorption is compared with that on the corresponding Fe3+-form resin and on a weakly acidic cation exchanger, Amberlite IRC-50. The amines used include aniline, m-hydroxyaniline, p-hydroxyaniline, m-nitroaniline, p-nitroaniline and p-carboxyaniline. Unlike the Fe3+-form resin which oxidizes some of these amines, such as aniline and hydroxyanilines, to insoluble products, thereby fouling the resin irreversibly, the Fe2+-form resin affords complete recovery of the sorbed species by acid stripping. The Fe2+-form resin also has higher sorption capacity (on dry basis) than the weak-acid cation exchanger. The stability constant of ligand sorption on the Fe2+-form resin increases markedly with the increasing basicity of the aromatic amines. The level of pH of the aqueous medium has a large influence on sorption capacity, sorption kinetics, and stability constant. While both the sorption capacity and sorption rate on the Fe2+-form resin increase markedly at lower pH, the stability constant, however, decreases. The ligand sorption kinetics at lower pH are well described by the unreacted-core model for unchanging particle size.
A recombinant strain, Escherichia coli JM109-AN1, was obtained by constructing of a genomic library of the total DNA of Delftia sp. AN3 in E. coli JM109 and screening for catechol 2,3-dioxygenase activity. This recombinant strain could grow on aniline as sole carbon, nitrogen and energy source. Enzymatic assays revealed that the exogenous genes including aniline dioxygenase (AD) and catechol 2,3-dioxygenase (C230) genes could well express in the recombinant strain with the activities of AD and C230 up to 0.31 U/mg wet cell and 1.92 U/mg crude proteins, respectively. The AD or C230 of strain AN3 could only catalyze aniline or catechol but not any other substituted substrates. This recombinant strain contained a recombinant plasmid, pKC505-ANl, in which a 29.7-kb DNA fragment from Delftia sp. AN3 was inserted. Sequencing and open reading frame (orfs) analysis of this 29.7 kb fragment revealed that it contained at least 27 orfs, among them a gene cluster (consisting of at least 16 genes, named danQTAlA2BRDCEFGlHIJKG2) was responsible for the complete metabolism of aniline to TCA-cycle intermediates. This gene cluster could be divided into two main parts, the upper sequences consisted of 7 genes (danQTAlA2BRD) were predicted to encode a multi-component aniline dioxygenase and a LysR-type regulator, and the central genes (danCEFGlHIJKG2) were expected to encode meto-cleavage pathway enzymes for catechol degradation to TCA-cycle intermediates. Unlike clusters tad from Delftia tsuruhatensis AD9 and tdn from Pseudomonas putida UCC22, in this gene cluster, all the genes were in the same transcriptional direction. There was only one set of C230 gene (danC) and ferredoxin-like protein gene (danD). The presence of only one set of these two genes and specificity of AD and C230 might be the reason for strain AN3 could only degrade aniline. The products of danQTAlA2BRDC showed 99%-100% identity to those from Delftia acidovorans 7N, and 50%-85% identity to those of tad cluster from D. tsuruhatensis AD9 in amino acid residues. Besides this dan cluster, the 29.7 kb fragment also contained genes encoding the trans-membrane transporter and transposases which might be needed for transposition of the gene cluster. Pulsed-field gel electrophoresis (PFGE) and plasmid curing experiments suggested that the dan cluster might be encoded on the chromosome of strain AN3. The GenBank accession number for the dan cluster of Delftia sp. AN3 is DQ661649.
The aim of this work was to develop a method for the clean-up and preconcentration of zearalenone from corn and wheat samples employing molecularly imprinted polymer (MIP) as selective sorbent for solid-phase extraction (SPE). Cereal samples were extracted with acetonitrile/water (75:25, v/v) and the extract was diluted with water and applied to an AFFINIMIP ZON MIP-SPE column. The column was then washed to eliminate the interferences and zearalenone was eluted with methanol and quantified using HPLC with fluorescence detection (lambda(exc)=275/lambda(em)=450 nm). The precision and accuracy of the method were satisfactory for both cereals at the different fortification levels tested and it gave recoveries between 82 and 87% (RSDr 2.5-6.2%, n=3) and 86 and 90% (RSDr 0.9-6.8%, n=3) for wheat and maize, respectively. MIP-SPE column capacity was determined to be not less than 6.6 microg of zearalenone and to be at least four times higher than that of immunoaffinity column (IAC). The application of AFFINIMIP ZON molecularly imprinted polymer as a selective sorbent material for detection of zearalenone fulfilled the method performance criteria required by the Commission Regulation (EC) No. 401/2006, demonstrating the suitability of the technique for the control of zearalenone in cereal samples.
The use of custom-made polymeric materials with high selectivities as target molecules in solid-phase extraction (SPE), known as molecularly imprinted solid-phase extraction (MISPE), is becoming an increasingly important sample preparation technique. However, the potential risk of leakage of the imprinting molecules during the desorption phase has limited application. The use of a mimicking template, called a dummy molecular imprinting polymer (DMIP), that bears the structure of a related molecule and acts as a putative imprinting molecule may provide a useful solution to this problem. In the current study, cyproheptadine (CPH) and azatadine (AZA) were used as templates in the development of an MIP and DMIP for acrylic acid and methacrylic acid monomers. Our results indicate that DMIPs have equal recognition of CPH, avoiding the problem of leakage of original template during the desorption phase relative to MIPs synthesized in presence of the print molecule CPH. Examination of the surface structure of the two polymer products by SEM shows appreciable differences in structural morphology and function of the monomers employed. These results are well supplemented by data obtained for swelling ratios and solvent uptake. Molecular modelling of CPH and AZA suggests that both substrates are similar in shape and volume.
The adsorption of DPKSH onto silica gel was investigated, at 25+/-1 degrees C and pH 1, 4.7 and 12. For the same DPKSH concentration interval, the minimum required time of contact for adsorption maximum at pH 4.7 was smaller than at pH 1 and the maximum amount of DPKSH adsorbed per gram of silica at pH 1 is smaller than at pH 4.7. At pH 12 the DPKSH adsorption onto silica gel was not significant. The adsorption data followed Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms. The maximum amount of solute adsorbed (m(ads)(max)) and the adsorption constant, K(L), were derived from Langmuir isotherm. The Freundlich constants 1/n and K(F) related, respectively, to the energetic heterogeneity of adsorption sites and an empirical constant were evaluated. The mean sorption free energy (E) of DPKSH adsorption onto silica gel was calculated from D-R isotherm indicating a physical adsorption mode. Finally, conductimetric titrations showed the silica particle basicity and acidity as 0.002 and 0.3mmolg(-1), respectively.
A single piezoelectric quartz crystal coated with one kind of crown ether was applied to the simultaneous determination of binary acid and amine vapor mixtures. From the adsorption and desorption curves of analytes, which were somewhat different in shape, frequency shifts from ten time windows were taken as inputs for artificial neural networks (ANN). Prediction results were satisfactory for ANN in both sample sets. The average relative errors, for formic acid and acrylic acid were 5%, for n-butylamine and aniline, they were 3% with ANN respectively. The effects of number of neurons in the hidden layer of ANN on the performance of the network are also discussed.
Synthetic polymer receptors selective for atrazine have been prepared by molecular imprinting using trialkylmelamines as template molecules in place of atrazine. Trialkylmelamines were shown to be useful as templates for introducing affinity for atrazine into ethylene glycol dimethacrylate-methacrylic acid copolymers. The polymers showed the selective binding capacity for triazine herbicides including atrazine, whereas agrochemicals in other categories were not adsorbed to the imprinted polymers. The group selectivity demonstrated was comparable with that of the original atrazine imprinted polymers. Use of the nonagrochemical template molecules as a substitution to atrazine has made it possible to synthesize herbicide-receptor polymers free from troubles caused by analyte contaminants, which are desired for analytical applications.
The adsorption of aniline from aqueous solutions onto cobalt(II)-poly(vinyl chloride)-carboxylated diaminoethane (PVC-CDAE) resin has been studied using a mini-column apparatus at 25+/-0.1 degrees C. First of all, experimental data obtained from the breakthrough curves were tested by using the Scatchard plot analysis, to have a preliminary prediction about the types of interaction of the resin with aniline. Our aim was to determine the model which best describes the experimental data. The aspect of the Scatchard plot indicated that the aniline adsorption did not follow the Langmuir model and the presence of two types of binding sites for aniline on the resin. However, the dynamics of aniline uptake were represented by the Freundlich model reasonably well. The kinetics of aniline adsorption from aqueous solution on the cobalt(II)-PVC-CDAE have also been tested using continuous column runs and rate-controlling step of the process was determined. In this study, homogeneous diffusion model was adapted to a column system to describe the change in the aniline concentration at the column exit beginning from breakthrough point as a function of time. Kinetic studies revealed that the rate-controlling step of the aniline adsorption was predominately film diffusion controlled rather particle diffusion.
In this paper a new bifunctional polymeric resin (LS-2) was synthesized by introducing sulfonic groups onto the surface of the resin during the post-crossing of chloromethyl low crosslinking macroporous poly-styrene resin, and the comparison of the adsorption properties of LS-2 with Amberlite XAD-4 toward aniline and 4-methylaniline in aqueous solutions was made. The study focuses on the static equilibrium adsorption behaviors, the adsorption thermodynamics, and the column dynamic adsorption and desorption profiles. Freundlich model gives a perfect fitting to the isotherm data. Although the specific surface area of LS-2 is lower than that of Amberlite XAD-4, the adsorbing capacities for these two adsorbates on LS-2 are higher than those on Amberlite XAD-4 within the temperature range 288-318 K, which is contributed to microporous structure and the polar groups on the network of LS-2 resins. The adsorption for aniline or 4-methylaniline on LS-2 was proved to be an endothermic process and increasing temperature was favorable. From the studies on the adsorption thermodynamics, static equilibrium adsorption, and the desorption conditions, an important conclusion can be drawn that the adsorption for aniline or 4-methylaniline on the LS-2 is a coexistence process of physical adsorption and chemical transition.
Molecularly imprinted polymers (MIPs) with selective recognition properties for zearalenone (ZON), an estrogenic mycotoxin, and structurally related compounds have been prepared using the non-covalent imprinting approach. A rationally designed ZON analogue, cyclododecyl 2,4-dihydroxybenzoate (CDHB), that exhibits resemblance to ZON in terms of size, shape and functionality has been synthesized and used as template for MIP preparation instead of the natural toxin. Several functional monomers have been evaluated to maximize the interactions with the template molecule during the polymerization process. The polymer material prepared with 1-allylpiperazine (1-ALPP) as functional monomer, trimethyl trimethacrylate (TRIM) as cross-linker and acetonitrile as porogen (in a 1:4:20 molar ratio) displayed superior binding capacities than any other of the MIPs tested. Selectivity of this material for ZON and structurally related and non-related compounds has been evaluated using it as stationary phase in liquid chromatography. Our results demonstrate that the imprinted polymer shows significant affinity in the porogenic solvent for the template mimic (CDHB) as well as for the ZON and other related target metabolites in food samples, dramatically improving the performance of previously reported MIPs for ZON recognition. Therefore, MIPs can be an excellent alternative for clean-up and preconcentration of the mycotoxin in contaminated food samples.
The removal of aniline from aqueous solutions by simultaneous use of ozone and activated carbon was investigated at different solution pH. For comparative purposes, single ozonation and adsorption on activated carbon were carried out in the same experimental set-up. In order to evaluate the role of the activated carbon surface chemistry during ozonation, a commercial activated carbon, Norit GAC 1240 PLUS, was submitted to oxidation in the liquid phase with HNO(3). The texture and surface chemistry of the activated carbon samples were characterized. During ozonation, complete conversion of aniline was achieved after approximately 20 min, regardless of the presence of activated carbon. In all cases, several by-products were formed during ozonation. Nitrobenzene, o- and p-aminophenol were the primary aromatic oxidation by-products identified. In terms of TOC removal, best results were achieved by the simultaneous use of ozone and activated carbon. Though there is a strong contribution of adsorption, a considerable synergetic effect between ozone and activated carbon is observed. In general, activated carbon promotes the reaction of ozonation enhancing the efficiency of this treatment process. The basic activated carbon presented greater activity in this process leading to higher mineralization rates.
Electrosorption-enhanced solid-phase microextraction (EE-SPME) based on activated carbon fiber (ACF) was developed for determination of aniline in aqueous solution. A porous ACF, served as working electrode in electrosorption procedure, was prepared and attached to a commercial manual SPME device. Parameters affecting the adsorption efficiency were investigated. Under optimized condition, which was 400 mV electrosorption potential, 0.01 M Na(2)SO(4) electrolyte, pH 7, and electrosorption at 40 degrees C for 10 min, the method exhibited wide linear range (0.1-100 microg L(-1), R(2)=0.9980), good repeatability of adsorption (RSD 6.15%, n=6), and low detection limit (0.02 microg L(-1)). The feasibility of the method was evaluated by analyzing lake water spiked with aniline. Comparison was made with direct immersion (DI) ACF-SPME without electrosorption enhancement. The proposed procedure was demonstrated to be a simple, fast, sensitive sample preparation method for determination of aniline in water samples.
A computational approach was developed to screening functional monomers and polymerization solvents for rational design of molecularly imprinted polymer (MIP). It was based on the comparison of the binding energy of the complexes between the template and different functional monomers. The effect of the polymerization solvent was included using the polarizable continuum model. According to the theoretical calculation results, the MIP with aniline as template was prepared by emulsion polymerization method using acrylamide (AAM) as functional monomer and divinylbenzene as cross-linker in carbon tetrachloride. The synthesized MIP was then tested by equilibrium-adsorption method, and the MIP demonstrated high removal efficiency to the aniline. The results of this study have indicated the possibility of using computer aided design for rational selection of functional monomers and solvents capable of removal of aniline from contaminated water.