Aniline Concentration Research Articles

Microbial Heterotrophic Nitrification-Aerobic Denitrification Dominates Simultaneous Removal of Aniline and Ammonium in Aquatic Ecosystems

A heterotrophic nitrification-aerobic denitrification (HN-AD) mixed culture was established as a simulated aquatic ecosystem to investigate the simultaneous removal of aniline and ammonium, as well as the succession of bacterial community. Aniline and ammonium were found to be simultaneously transformed, with maximum removal efficiencies of 99.98% and 89.87%, respectively. The presence of aniline at lower concentrations (0 to 100 mg/L) slightly inhibited ammonium oxidation, whereas further increasing the aniline concentration (from 100 to 500 mg/L) yielded an apparent enhancement effect, increasing the ammonium-N removal rate from 0.33 to 1.26 mg/L/day. In contrast, ammonium-N concentrations of 100 mg/L were able to facilitate aniline removal. Ammonium was the preferred nitrogen source for aniline removal when compared with nitrification metabolites such as nitrate or nitrite. The analysis of microbial community succession using high-throughput sequencing revealed that the microbial diversity generally decreased throughout the aniline and ammonium removal process. Proteobacteria is observed to increase at the climax stage, and the average relative abundances of Pseudomonas, Massilia, and Bacillus were highest at the climax stage and were positively related to the removal rate of aniline and ammonium-N. Surprisingly, the abundance of these microbes at the end stage was almost equal to that observed at the initial stage. This study demonstrated that polluted aquatic ecosystems hold potential for simultaneous removal of pollutants (hazardous organic carbon and ammonium), and have excellent self-rehabilitation abilities.

Polyaniline/Poly(acrylamide‐co‐sodium acrylate) Porous Conductive Hydrogels with High Stretchability by Freeze‐Thaw‐Shrink Treatment for Flexible Electrodes

AbstractWith the development of alternatives to traditional fossil energy and the rise of wearable technology, flexible energy storage devices have attracted great attention. In this paper, a polyaniline/poly(acrylamide‐sodium acrylate copolymer) hydrogel (PASH) with high flexibility and excellent electrochemical properties for flexible electrodes is fabricated by freeze‐thaw‐shrink treatment of a highly water‐absorptive hydrogel, together with in‐situ polymerization of aniline at a low aniline concentration (0.1 mol L−1). The PASH exhibits a conductivity of 4.05 S m−1 and an elongation at break of 1245%. The freeze‐thaw‐shrink treatment greatly improves the electrochemical performance and stability of the conductive PASH. The area specific capacitance of PASH reaches 849 mF cm−2 and the capacitance maintains 89% after 1000 galvanostatic charge–discharge cycles. All the raw materials are conventional industrialized materials and no additional templating agent is needed during the entire synthesis process. This study provides a cost‐efficient approach for the fabrication of conductive polymer hydrogels, which has a broad application prospect in flexible energy storage electronic devices.

Effect of organic coatings derived from the OH-initiated oxidation of amines on soot morphology and cloud activation

The presence of coatings on soot particles may significantly influence their environmental impacts. In this study, the processing of soot by OH-initiated photooxidation of amines was investigated in a series of chamber experiments. Monodisperse soot aerosol was exposed to oxidation products of monoethanolamine (MEA), triethylamine (TEA) and aniline, and changes in particle size, mass, effective density, shape factor, and activation as cloud condensation nuclei (CCN) were simultaneously measured by a suite of instruments. Different initial concentrations of amine precursor were applied, and in selected experiments, organic coatings were removed by thermal denuding to investigate the change of the soot core structure. Aniline generated the largest amount of low volatility condensable oxidation products, which induced minimal soot restructuring even at a high aniline concentration. On the contrary, the high volatility of MEA oxidation products led to reversible condensation on soot while inducing significant aggregate collapse for a smaller coating mass than with aniline. The products from TEA photooxidation showed volatility intermediate between aniline and MEA and induced the most significant restructuring. It can be concluded that restructuring depended on the physical state of the coating material and its distribution over the aggregate surface. Soot aged with the three different amine precursors produced distinct CCN activity profiles that depended on measured coating mass, and there was an indication that intermediate volatility oxidation products of MEA co-condensed with water during the droplet activation process.

Environmentally friendly synthesis of Fe2O3@SiO2 nanocomposite: characterization and application as an adsorbent to aniline removal from aqueous solution.

Silica-based nanocomposite syntheses employ many harmful substances, which, in turn, demand the development of new synthetic environmental-friendly routes that meet the principles of green chemistry. In this work, we present a novel magnetic adsorbent, Fe2O3@SiO2 nanocomposite (Fe@SiNp), successfully obtained without surfactant, employing an electrochemical method. We characterized the nanocomposite and then applied it to remove aniline from the water medium. Characterization was carried out by vibrating-sample magnetometry (VSM), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR). The parameters to the adsorptive removal of aniline were successfully optimized, which made possible to remove 71.04 ± 0.06% (126.6 ± 2.0mg/g) from a 100mg/L aniline solution at pH6 and 323K, by employing around 50mg of Fe@SiNp, at a contact time of 40min. The adsorption of aniline by Fe@SiNp is a spontaneous and exothermic process according to the pseudo-second-order kinetic model (r2 = 1 at 20mg/L aniline concentration) and the Freundlich isotherm model (r2 = 0.9986).

Carbon Materials Derived from Poly(aniline-co-p-phenylenediamine) Cryogels.

Nitrogen-containing carbon derivatives were prepared by the carbonization of poly(aniline-co-p-phenylenediamine) cryogels in inert atmosphere. Lower aniline fraction in the comonomer mixture used for preparation of the cryogels led to the decrease of their thermal stability, a consequent increase of carbonization degree, and less defective structure of carbonized materials. The resulting carbonaceous products had up to 4 orders of magnitude higher specific surface area than their respective cryogel precursors, the highest value 931 m2 g−1 being achieved for carbonized poly(p-phenylenediamine) cryogel. Electrochemical characterization of the carbon derivatives demonstrated that the decrease in aniline concentration during the synthesis of the precursor cryogels led to higher gravimetric capacitance for corresponding carbonized materials. These materials can potentially be used for energy storage applications.

Surface modification of poly (L-lactic acid) films to improve electrical conductivity by surface entrapment/in situ polymerization methods

Electrical properties play an important role in the interaction of cells and biomaterials. The aim of this study was to increase surface electrical conductivity of poly (L-lactic acid) (PLLA) films by polyaniline (PANI) using surface entrapment (SE) and surface entrapment in situ polymerization (SEIP) methods. The entrapment modification technique was performed by the reversible gelation of the PLLA surface region following exposure to a solvent and non-solvent mixture, while PANI chains were diffused into the swollen PLLA surface. In SEIP method, PANI was entrapped through in situ chemical oxidative polymerization of aniline on PLLA films. The effects of PANI concentration, the ratios of solvents and immersion time on the electrical conductivity were studied by SE method. The effects of aniline concentration, doping effect, temperature and time of polymerization were evaluated by SEIP method too. The results obtained by attenuated total reflection Fourier transformer infrared spectroscopy, scanning electron microscopy and energy dispersive x-ray mapping analysis confirmed the presence of PANI on the surface of PLLA films. UV-visible analysis was employed to investigate the doping effect on the reduction of energy and conductivity of the films. Experimental results also indicated that the electrical conductivity, uniformity and density of the SEIP modified films were significant in comparison to those of the modified films by SE method.

Electrochemically prepared three-dimensional reduced graphene oxide-polyaniline nanocomposite as a solid-phase microextraction coating for ethion determination

Here, a three-dimensional reduced graphene oxide-polyaniline nanocomposite was synthesized and applied as a sorbent for solid-phase microextraction of ethion from water samples followed by negative corona discharge ionization ion mobility spectrometry. The nanocomposite was synthesized via a fast and facile two-step electrochemical method. The prepared sorbent was characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscopy and thermogravimetric analysis. The main experimental parameters in the preparation of the fiber including concentration of graphene oxide, electrodeposition time, aniline concentration, and electropolymerization time were investigated. Also, parameters affecting the extraction process (i.e., salt addition, sample stirring rate, solution pH, extraction temperature and extraction time) were studied. Under the optimal conditions, the linearity and limit of detection were found to be 1.0–70 and 0.4 μg L−1, respectively. The method presented good precision (intra-day and inter-day, n = 3), ranged from 1.7 to 4.7%. The analyte recovery obtained using spiked real water samples were in the range of 84–98%.

New insights into aniline toxicity: Aniline exposure triggers envelope stress and extracellular polymeric substance formation in Rubrivivax benzoatilyticus JA2

Aniline is a major environmental pollutant of serious concern due to its toxicity. Although microbial metabolism of aniline is well-studied, its toxic effects and physiological responses of microorganisms to aniline are largely unexplored. Rubrivivax benzoatilyticus JA2, an aniline non-degrading bacterium, tolerates high concentrations of aniline and produces extracellular polymeric substance(EPS). Surprisingly, strain JA2 forms EPS only when exposed to aniline and other toxic compounds like organic solvents and heavy metals indicating that EPS formation is coupled to cell toxicity. Further, extensive reanalysis of the previous proteomic data of aniline exposed cells revealed up-regulation of envelope stress response(ESR) proteins such as periplasmic protein folding, envelope integrity, transmembrane complex, and cell-wall remodelling proteins. In silico analysis and molecular modeling of three highly up-regulated proteins revealed that these proteins were homologous to CpxARP proteins of ESR signalling pathway. Furthermore, EPS formation to known ESR activators(Triton-X-100, EDTA) suggests that envelope stress possibly regulating the EPS production. The present study suggests that aniline triggers envelope stress; to counter this strain JA2 activates ESR pathway and EPS production. Our study revealed the hitherto unknown toxic effects of aniline as an acute envelope stressor thus toxicity of aniline may be more profound to life-forms than previously thought.

Electrochemical synthesis of polyaniline on activated carbon surface and its electromagnetic properties

In order to improve the electromagnetic properties of single polyaniline (PANI), polyaniline/activated carbon (PANI/AC) composites were prepared on the surface of an activated carbon-pencil core electrode (AC-PEC) by cyclic voltammetry of electrochemical synthetic method. The preparation conditions were optimized using charge of composite material, such as scanning potential range, scanning rate, aniline concentration, supporting electrolyte concentration, number of scanning cycles, applied neutral electrolyte concentration, concentration of activated carbon dispersion and effective conduction length of AC-PEC. The optimized results show that the as-prepared PANI/AC has the highest charge and the best stability when AC-PEC with 1.5 cm effective length (75mg/mL activated carbon dispersing liquid concentration) is put in a mixture solution (pH=0.22) containing 0.3 mol/L H₂SO₄, 0.2 mol/L KCl and 0.2 mol/L aniline (An) at the scanning speed of 0.04 V/s in a potential range from -0.4 V to 1.1 V with 8 cycles scanning successively. PANI/AC exhibits a kind of core-shell structure with good conductivity, and its impedance is lower than those of PANI and AC. It can absorb electromagnetic wave of 7.44-15.12 GHz in varying degrees, which is wider than that of pure PANI in the range from 10.48 GHz to 14.32 GHz.

Characterization and Photo-catalytic Efficiency of MnFe2O4/Zn2SiO4 for Aniline Degradation Using Box-Behnken Experimental Design and Simulated Solar Radiation

In this research, Zn2SiO4 as a support and MnFe2O4 as a main photo-catalyst were individually syn-thesized and MnFe2O4 was fixed on Zn2SiO4 with solid state dispersion method. MnFe2O4 nano pho-to-catalyst was synthesized by co-precipitation method and reflux condition for 12 hours at 85°C in the presence of urea. For identification of catalysts Fourier-transform infrared (FTIR) spectroscopy, Field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDXS), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray fluorescence (XRF) and Brunauer-Emmett-Teller (BET) techniques were used. The size of MnFe2O4 was determined about 15 nm after the fixation on the Zn2SiO4. The photo-catalytic efficiency of MnFe2O4/Zn2SiO4 was checked for degradation of aniline aqueous solu-tion utilizing the irradiation of a 1 kW Xe lamp fitted with the AM1.5 filter (to simulate the solar light spectrum) in the presence of H2O2. Degradation process was modeled and optimized successfully ap-plying response surface methodology (RSM) according to Box-Behnken designs. Experiment results were showed that initial concentration of aniline=5.5 ppm, H2O2 initial concentration=5.3 mM, pH=11 and nano photo-catalyst amount =0.4 g/L are optimal conditions and the degradation effi-ciency in this condition achieved is 96%. In the optimum conditions, arrangement of (MnFe2O4/Zn2SiO4)> (MnFe2O4)> (Zn2SiO4) was obtained for efficiency of photo-catalytic degrada-tion of aniline in aqueous solution. Decomposition kinetic equation determined pseudo first order and k=0.0407.

Preparation and performance of PANI-TiO2 nanotube arrays composite electrode by in-situ microcavity polymerization

TiO2 nanotube arrays (TNTA) were firstly impregnated with ethanol solution containing aniline monomer, then the polyaniline-TiO2 nanotube arrays (PANI-TNTA) composite electrode was prepared through polymerization of aniline monomer in the microcavity of the nanotubes using ammonium persulfate (APS) as the initiator. The effects of aniline and APS concentration on the properties of the composite electrodes were studied. The electrochemical performances of the composite electrode in sodium sulfate aqueous solution and sulfuric acid aqueous solution were compared at different potential windows of −0.2–1 V and −0.2–1.8 V. Results show that the composite electrode exhibits optimal performance when the concentration of aniline and APS is 0.2 M and 0.05 M, respectively. The composite electrode has fair good electrochemical performances under various testing conditions especially in sulfuric acid aqueous solution, it has a maximum capacitance of 816.7 F g−1, and at the enlarged potential window of −0.2–1.8 V, its energy densities are higher than those of −0.2–1 V. The composite electrode also has excellent rate and cycling properties.

Facile synthesis of curly conductive polyaniline composite fibers using cattail fluff as substrate

Cattail fluff is widely distributed in nature. Scanning electron microscopy revealed it has a curly flexible characteristic with groove structure. Novel flexible composite fibers with good conductivity were synthesized by using cattail fluff as substrate via in situ polymerization. Aniline monomers were absorbed and polymerized on the cattail fluff fibers. The conductivities of the composite fibers increase with the increasing aniline concentration. This method is very simple and effective. These flexible conductive composite fibers may find potential applications in flexible electronic devices.

Fluorescence quenching of novel pyrazoline derivative with aniline in different solvents

The fluorescence quenching process of a new pyrazoline derivative (4-[5-(2,3,4-trimethoxyphenyl)-3-(4-trifluoromethylphenyl)-4,5-dihydro-1H-pyrazole-1-yl] benzensulfonamide, fluorophore T) and aniline was investigated in four different solvents (tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), acetonitrile (ACN) and Ethanol (EtOH)) by using UV–vis. absorption, steady-state and time-resolved fluorescence techniques. According to the data obtained, it was determined that fluorescence intensity of fluorophore T decreased as the concentration of aniline increased in all solvents used due to the fluorescence quenching process between fluorophore T and aniline. The mechanism of the quenching process between the fluorophore T and the aniline was explained by Stern-Volmer plots. The fluorescence quenching parameters such as Stern-Volmer constants (KS and KD), bimolecular quenching constants (kq), the probability of quenching per encounter (p) and activation energy of quenching (Ea) were determined from both steady-state and time-resolved measurements. The results obtained with the modified Stern-Volmer equation presented that the fluorescence quenching process quenching is dominated by static interactions between the fluorophore T and the aniline with a minor dynamic component. In addition, the calculated activation energy of quenching (Ea) values confirmed that the quenching process did not occur with material diffusion only. It is thought that fluorophore T can be used for aniline detection via fluorescence quenching in future.

A toxic effect at molecular level can be expressed at community level: A case study on toxic hierarchy

This study demonstrated hierarchical toxicity and addressed the relevance and differences of toxic effects at the molecular, individual, population, and community levels. Superoxide dismutase (SOD) activity, photosynthetic oxygen production, filtration rate, life span and densities of Platymonas helgolandica var. tsingtaoensis, Isochrysis galbana, and Brachionus plicatilis in single-species tests and customized community tests were examined in response to a concentration gradient of aniline ranging from 0 to 50.0 mg L−1. The SOD activity was the most sensitive endpoint with the fastest response to aniline according to the calculated no-detection of toxic effect concentration (NDEC) and the EC50. The individual- and population-level endpoints, showing a lower response to aniline, could be constructed from the SOD activity in a stepwise manner. A multi-scale hierarchical model with endpoints at 4 levels was used to characterize toxic effects, at the scales of time and size. Linkage of SOD activity to toxic effects at a community level was established level by level to express the change in the customized community with the concentration of aniline. The calculated threshold concentration of aniline for the customized community was nearly equal to the minimum NDEC, demonstrating as great an impact on interactions by the toxic effect at subpopulation-level as that at the community level. However, we identified a trend of higher sensitivities of measured endpoints at sub-population level, decreasing sensitivity at higher levels but a great variety of sensitivities at community level. Although the characteristics of toxic effects are different at different levels, the structure and process of endpoints at adjacent levels are related to and interact with each other. The resulted indirect effects, together with direct effect, determine the toxic effect at every levels of biological complexity. The toxic effects at adjacent levels should be studied at the same time to better understand the ecological risk of contaminants.

Decomposition of refractory aniline aerofloat collector in aqueous solution by an ozone/vacuum-UV (O3/VUV) process

ABSTRACT The degradation of refractory aniline aerofloat (AAF) collector was investigated by an ozone/Vacuum-UV (O3/VUV) process. The effects of O3 dosage and initial pH on the AAF degradation were studied. The total organic carbon (TOC) and concentrations of , and anions were measured to evaluate the AAF mineralization. The solid phase extraction and gas chromatography–mass spectrometry (SPE/GC–MS) was developed to identify byproducts. The results showed that 99.84% of AAF could be removed by the O3/VUV, and the AAF degradation was enhanced at higher O3 dosage and initial solution pH. The radical scavenging tests revealed that most of AAF was degraded by OH• radicals, and the O3/UV254nm made the main contribution in AAF degradation in the O3/VUV system. The mineralization extents of C, S, P and N elements of AAF at 180 min reached 47.74%, 93.94%, 17.71% and 45.81%, respectively. At initial pH > 10.0, the EE/O values of AAF degradation by the O3/VUV was below 7.0 kWh m−3 per order, showing the energy consumption was acceptable. The SPE/GC–MS analysis showed that toxic aniline was generated in the O3/VUV oxidation of AAF, but it was further degraded at a longer time. Compared to the ozonation, the O3/VUV had a much lower content of aniline at 180 min. The possible degradation pathways of AAF by the O3/VUV were proposed.

Plasmonic Switching of the Reaction Pathway: Visible‐Light Irradiation Varies the Reactant Concentration at the Solid–Solution Interface of a Gold–Cobalt Catalyst

AbstractProduct selectivity of alkyne hydroamination over catalytic Au2Co alloy nanoparticles (NPs) can be made switchable by a light‐on/light‐off process, yielding imine (cross‐coupling product of aniline and alkyne) under visible‐light irradiation, but 1,4‐diphenylbutadiyne in the dark. The low‐flux light irradiation concentrates aniline on the catalyst, accelerating the catalytic cross‐coupling by several orders of magnitude even at a very low overall aniline concentrations (1.0×10−3 mol L−1). A tentative mechanism is that Au2Co NPs absorb light, generating an intense fringing electromagnetic field and hot electrons. The sharp field‐gradient (plasmonic optical force) can selectively enhance adsorption of light‐polarizable aniline molecules on the catalyst. The light irradiation thereby alters the aniline/alkyne ratio at the NPs surface, switching product selectivity. This represents a new paradigm to modify a catalysis process by light.

Plasmonic Switching of the Reaction Pathway: Visible-Light Irradiation Varies the Reactant Concentration at the Solid-Solution Interface of a Gold-Cobalt Catalyst.

Product selectivity of alkyne hydroamination over catalytic Au2 Co alloy nanoparticles (NPs) can be made switchable by a light-on/light-off process, yielding imine (cross-coupling product of aniline and alkyne) under visible-light irradiation, but 1,4-diphenylbutadiyne in the dark. The low-flux light irradiation concentrates aniline on the catalyst, accelerating the catalytic cross-coupling by several orders of magnitude even at a very low overall aniline concentrations (1.0×10-3 mol L-1 ). A tentative mechanism is that Au2 Co NPs absorb light, generating an intense fringing electromagnetic field and hot electrons. The sharp field-gradient (plasmonic optical force) can selectively enhance adsorption of light-polarizable aniline molecules on the catalyst. The light irradiation thereby alters the aniline/alkyne ratio at the NPs surface, switching product selectivity. This represents a new paradigm to modify a catalysis process by light.

Effects of preparation conditions on the supercapacitor performances of MnO2-PANI/titanium foam composite electrodes

MnO2-polyaniline (PANI)/titanium foam composite electrodes were prepared by a two-step cyclic voltammetry method with titanium foam as the current collector and aniline and manganese acetate solution as the deposition electrolytes. The effects of monomer concentration, deposition time, and scan rate on the supercapacitor performances of the composite electrodes were studied. The reasons for the change of capacitance were discussed by electrochemical impedance spectroscopy and deposition curves. Results show that nanoscale PANI and MnO2 are uniformly combined in the composite electrode. The redox reversibility and deposition amount of PANI are affected by the concentration and deposition scan rate of aniline. The concentration and deposition scan rate of manganese acetate mainly influence the deposition state of MnO2 and the compactness of the composite film. Under the optimized conditions, the composite electrode has a high capacitance value of 97.38 mF cm−2 (945.44 F g−1) at a current density of 0.2 mA cm−2 and exhibits superior cycling performance.

Preparing chitosan–polyaniline nanocomposite film and examining its mechanical, electrical, and antimicrobial properties

In recent years, development and progress in modern packaging resulting from degradable natural resources have grown remarkably. In this study, chitosan–polyaniline film was prepared with a combination of different concentrations of polyaniline and various synthesis times to produce antimicrobial and biodegradable packaging film. The physical, electrical, and mechanical properties of the films were investigated. The interaction between chitosan and polyaniline was confirmed by Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction patterns. The size and morphology of the synthesized particles were examined by scanning electron microscopy. The results indicated that the synthesized polyaniline particles had a spherical shape (45–100 nm). The antimicrobial and antifungal activity of the films against Aspergillus niger fungi (antifungal area: 61.47 mm2) and Escherichia coli bacteria (antimicrobial area: 187.27 mm2) increased with increasing the concentration of polyaniline. The results obtained from the study of the effect of polyaniline on the electrical conductivity of the chitosan film showed that increasing the polyaniline concentration and synthesis time resulted in decreased electrical resistance of the film, for which the film with the highest aniline concentration and the highest synthesize time had the lowest resistance. According to the mechanical property results, tensile strength (TS) and elastic modulus were increased due to the addition of the polyaniline to the polymer matrix. The chitosan blank film had a lower TS than nanocomposites. As the final results, the chitosan–polyaniline film has good electrical conductivity, indicating that the produced film could be used in intelligent food packaging.

The synergistic effect of biophoto anode for the enhancement of current generation and degradation

ABSTRACT The demand for removal of refractory organic pollutants limits the application of microbial fuel cells. In this study, the synergistic effects of bioelectrochemical and photocatalysis methods were captured by constructing a biophoto anode from a combination of WO3/TiO2 and carbon felt. This biophoto electrode was able to decrease the aniline concentration from 63.3 ± 6.2 to 9.3 ± 5.5 mg/L. The structure of the benzene ring was broken through strong oxidation by photocatalysis. Electrochemical analysis showed that photocatalysis also enhanced the extracellular electron transfer of microorganisms and reduced the resistance of the anode from 136.9 Ω to 69.9 Ω. In addition, the maximum current output increased by 28.5% under the composite biophoto electrode. Further analysis of the microbial community indicated that the biophoto electrode promoted the enrichment of Geobacter in the anode. This biophoto electrode provided a method for overcoming the disadvantages of anaerobic degradation of refractory organics.