Showing papers on "Nitrobenzene published in 2011"
TL;DR: Reduced graphene oxide was used as a catalyst for reduction of nitrobenzene at room temperature and N-phenylhydroxylamine was proved to be the intermediate in this catalytic reaction.
381 citations
TL;DR: Investigation of the conversion of NB to aniline (AN), a less toxic endproduct that can easily be mineralized, using a fed-batch bioelectrochemical system with microbially catalyzed cathode indicated that the cathode was dominated by an Enterococcus species closely related toEnterococcus aquimarinus.
Abstract: Nitrobenzene (NB) is a toxic compound that is often found as a pollutant in the environment. The present removal strategies suffer from high cost or slow conversion rate. Here, we investigated the conversion of NB to aniline (AN), a less toxic endproduct that can easily be mineralized, using a fed-batch bioelectrochemical system with microbially catalyzed cathode. When a voltage of 0.5 V was applied in the presence of glucose, 88.2 ± 0.60% of the supplied NB (0.5 mM) was transformed to AN within 24 h, which was 10.25 and 2.90 times higher than an abiotic cathode and open circuit controlled experiment, respectively. AN was the only product detected during bioelectrochemical reduction of NB (maximum efficiency 98.70 ± 0.87%), whereas in abiotic conditions nitrosobenzene was observed as intermediate of NB reduction to AN (decreased efficiency to 73.75 ± 3.2%). When glucose was replaced by NaHCO(3), the rate of NB degradation decreased about 10%, selective transformation of NB to AN was still achieved (98.93 ± 0.77%). Upon autoclaving the cathode electrode, nitrosobenzene was formed as an intermediate, leading to a decreased AN formation efficiency of 71.6%. Cyclic voltammetry highlighted higher peak currents as well as decreased overpotentials for NB reduction at the biocathode. 16S rRNA based analysis of the biofilm on the cathode indicated that the cathode was dominated by an Enterococcus species closely related to Enterococcus aquimarinus.
248 citations
TL;DR: In this paper, the adsorption of nitrobenzene on MIL-53(Al) was carried out at 30 ± 1 °C using batch experiments, whereas no significant difference was observed in acidic pH.
Abstract: MIL-53(Al), hydrothermally synthesized and purified by solvent extraction, was used as adsorbent for the removal of nitrobenzene from aqueous solution. Pristine MIL-53(Al) and MIL-53(Al) loaded with various amounts of nitrobenzene were characterized by X-ray diffraction analysis with cell indexation study, thermogravimetric analysis, Fourier transform infrared spectroscopy, and BET surface area. A simulation study of nitrobenzene adsorption on MIL-53(Al) was performed. The adsorption study of nitrobenzene on MIL-53(Al) was carried out at 30 ± 1 °C using batch experiments. The amount of nitrobenzene adsorbed decreases with an increase in the temperature from 30° to 60 °C and pH from 8 to 11, whereas no significant difference was observed in acidic pH. The adsorption data were fitted to Sips and Redlich–Peterson isotherm models. The adsorption capacity of nitrobenzene on MIL-53(Al) obtained was 610 mg/g, higher than that of zeolites (267.2 mg/g) and organoclays (100 mg/g), but, lower than that of modified c...
116 citations
TL;DR: In this paper, blue light irradiation of heterogeneous photocatalysts PbBiO2X in the presence of triethanolamine as an electron donor leads to hydrogen evolution, and the selective, clean and complete reduction of nitrobenzene derivatives to their corresponding anilines.
76 citations
TL;DR: The three-phase hydrogenation of nitrobenzene catalysed by nanosized gold over titania was investigated in a slurry and the spectroscopic measurements provided new insights into the reaction mechanism and an update of the corresponding kinetics.
Abstract: The three-phase hydrogenation of nitrobenzene catalysed by nanosized gold over titania was investigated in a slurry. Simultaneous in situ ATR-FTIR monitoring of the liquid phase and at the solid/liquid catalyst interface identified the species adsorbed on the catalyst and those in the liquid phase during the reaction. Nitrosobenzene was not detected analytically while the spectroscopic measurements strongly indicated phenylhydroxylamine as an intermediate reacting before desorbing from the catalyst surface. Under the same reaction conditions, azobenzene and hydrazobenzene were identified as intermediates during the hydrogenation of azoxybenzene to aniline. When nitrosobenzene or phenylhydroxylamine was alternately fed as reactant, azoxybenzene was produced via a disproportionation route. With the former, azoxybenzene was not further reduced by hydrogen because nitrosobenzene deactivated the catalyst. Combined with H2 uptake, the spectroscopic measurements provided new insights into the reaction mechanism of the gold catalysed hydrogenation of nitrobenzene and an update of the corresponding kinetics.
75 citations
TL;DR: In this article, the results of the studies on adsorption of nitrobenzene and humic acid from aqueous solution onto activated carbon commercial (ACC) grade were reported.
67 citations
TL;DR: In this article, an amorphous blue phase III with low and wide thermal range (∼20 °C) including room temperature is induced by doping a bent-core nematic with a strong chiral material.
Abstract: An amorphous blue phase III with low and wide thermal range (∼20 °C) including room temperature is induced by doping a bent-core nematic with a strong chiral material. We confirm that the electrooptical response is due to the Kerr effect, with the Kerr constant being up to two orders of magnitude larger than conventional Kerr materials such as nitrobenzene.
66 citations
TL;DR: In this paper, a thermally coupled steam reformer with an endothermic side and the hydrogenation of nitrobenzene to aniline in the exothermic is investigated.
51 citations
TL;DR: The quantitative relationship between the amount of adsorbed compounds and modified functional groups and the fitting for adsorbent isotherm models suggested that this adsorption might form a multi-layer adsorptive in the most cases.
44 citations
TL;DR: In this article, a cetyl trimethylammonium bromide (CTAB) surfactant-assisted technique was used to synthesize Zn-BDC nanorods with a 2D layered structure.
40 citations
TL;DR: In this article, the biodegradation of nitrobenzene by granular sludge was investigated, and the results may provide a guideline for nitronzene wastewater treatment.
TL;DR: In this article, a commercial activated carbon (AC) was modified by oxidation with HNO3 followed by heat treatment in a nitrogen atmosphere to enhance nitrobenzene removal from aqueous solution.
Abstract: To enhance nitrobenzene removal from aqueous solution, commercial activated carbon (AC) was modified by oxidation with HNO3 followed by heat treatment in a nitrogen atmosphere. The modification process introduced oxygen-containing functional groups and changed the charge properties of the AC surface. The effects of surface chemical properties and pore structure on the adsorption of nitrobenzene by the AC were investigated through kinetics and equilibrium isotherms. HNO3 oxidation modified the surface chemical properties and increased the number of acidic oxygen-containing surface groups, but had an almost negligible effect on the pore structure. Subsequent heat treatment caused decomposition of oxygen-containing functional groups on the AC surface, increased the pH point of zero charge (pHPZC) and increased the number of mesopores. The maximum adsorption capacity achieved by the modified AC was 1,443.53 mg g−1, 3.33 times of that unmodified AC. HNO3 oxidation combined with heat treatment was an effective method for the preparation of AC with high nitrobenzene adsorption capacity and fast adsorption kinetics. An appropriate pHPZC, amount of surface oxygen groups and the presence of well-developed mesopores together with micropores were the main reasons for the high nitrobenzene adsorption capacity of the modified AC.
TL;DR: The results showed that nanoscale Fe/Au particles exhibited higher catalytic activity than bulk gold for nitrobenzene reduction, and were found to be the electrolysis product.
TL;DR: Trace amounts of urea derivatives enhance the rate of nitrobenzene N3-sensitized TiO(2) photoreduction by catalyzing the proton transfer, facilitating its application in organic synthesis.
Abstract: Trace amounts of urea derivatives enhance the rate of nitrobenzene N3-sensitized TiO2 photoreduction by catalyzing the proton transfer. The usually required addition of transition metal co-catalysts becomes dispensable for this visible light photocatalysis, facilitating its application in organic synthesis.
TL;DR: This paper showed that neutral fullerenes (C60 and C70) are not a non-metal catalyst for molecular hydrogen activation under UV irradiation at room temperature and hydrogenation of aromatic nitro compounds to the corresponding aromatic amines.
Abstract: A recent report claimed that fullerene is a nonmetal catalyst for molecular activation of hydrogen, and that its catalytic activity is comparable to that of a noble metal catalyst. Li and Xu showed neutral fullerenes (C60 and C70) to activate molecular hydrogen under UV irradiation at room temperature and hydrogenation of aromatic nitro compounds to the corresponding aromatic amines took place with high yields and selectivities under 0.1 MPa of hydrogen. In control experiments in the absence of UV irradiation, the reduction of the nitro compounds did not proceed at 0.1 MPa H2. The mechanism of the molecular hydrogen activation in these systems is unclear at present. They also showed activated fullerene (fullerene anion) to effectively catalyze the hydrogenation of nitrobenzene to aniline, under dark conditions and at elevated temperature and pressure, with high selectivity. These findings could revolutionize catalysis, because fullerenes are environmentally friendly and their application would reduce costs. Nonmetal-catalyzed hydrogenation is an exciting prospect. We were interested in the mechanism of the molecular hydrogen activation under dark conditions and the subsequent transfer of hydrogen to the substrate, and thus reproduced the experiments. We did not address the hydrogenation of nitro compounds with neutral fullerene under UV irradiation and ambient conditions in this study. Herein, we demonstrate that C60 is not a nonmetal catalyst for hydrogenation. To produce the active catalyst, C60 was treated with solid NaOH and a Ni Al alloy in a nitrogen atmosphere. After adding THF and water, a reduction occurred and a red cloudlike fullerene monoanion (C60 ) product formed. The product diffused into the THF layer, the color of which became dark violet. After approximately 15 min, the violet THF phase was separated from the colorless aqueous solution. The THF phase was then used for the hydrogenation of nitrobenzene. In a typical reaction, C60 or C60 (0.019 mmol), nitrobenzene (3.25 mmol), mesitylene (0.50 mmol) as the internal standard, and THF (25 mL) as the solvent were placed into a stainless steel autoclave at 100 8C (or 150 8C) and 5 MPa H2 pressure. The control reaction without catalyst gave 2.3 % conversion at 100 8C (Table 1, entry 1). With 0.019 mmol C60 catalyst, the conversion was equally low (Table 1, entry 2), indicating that untreated C60 is inactive in hydrogenation reactions. [4] An increase in temperature to 150 8C led to an increase in conversion to
TL;DR: Two new Schiff bases (I) and (II) containing nitrogen-sulfur-oxygen donor atoms were designed and synthesized in a multi-step reaction sequence and revealed a synergistic effect of this donors on extraction of UO2(2+) and Hg2+ by the studied Schiff base (I).
TL;DR: In this paper, the surface of attapulgite was cleaned, modified with 3-aminpropyltriethoxysilane, and then covered with silver nanoparticles.
Abstract: The surface of attapulgite was cleaned, modified with 3-aminpropyltriethoxysilane, and then covered with silver nanoparticles. The structure and morphology of the modified attapulgite were characterized by infrared spectroscopy, X-ray diffraction and transmission electron microscopy (TEM). TEM revealed that the silver nanoparticles were deposited on the surface of rod-like attapulgites. The composite material was used for electrochemical determination of nitrobenzene by taking advantage of the capability of the nanocomposites to catalyze the reduction of nitrobenzene. The relationship between peak current and the concentration of nitrobenzene is linear in the range from 3 to 30 μM, and the lowest detectable concentration is 1.1 μM.
TL;DR: In this article, the density functional theory (DFT) calculations were applied to derive the most probable structure of the tetrakis(2-ethoxyethoxy)-tetra-p-tert-butylcalix[4]arene·H3O+ complex species.
Abstract: Extraction experiments in the two-phase water/nitrobenzene system and γ-activity measurements were used to determine the stability constant of protonated tetrakis(2-ethoxyethoxy)-tetra-p-tert-butylcalix[4]arene in nitrobenzene saturated with water. Density functional theory (DFT) calculations were applied to derive the most probable structure of the tetrakis(2-ethoxyethoxy)-tetra-p-tert-butylcalix[4]arene·H3O+ complex species.
TL;DR: It is proposed that the Pd-imido species is the central key intermediate that can link together all reduction products of nitrobenzene and all oxidation products of methanol in one unified mechanistic scheme.
Abstract: The reactivity of palladium complexes of bidentate diaryl phosphane ligands (P(2)) was studied in the reaction of nitrobenzene with CO in methanol. Careful analysis of the reaction mixtures revealed that, besides the frequently reported reduction products of nitrobenzene [methyl phenyl carbamate (MPC), N,N'-diphenylurea (DPU), aniline, azobenzene (Azo) and azoxybenzene (Azoxy)], large quantities of oxidation products of methanol were co-produced (dimethyl carbonate (DMC), dimethyl oxalate (DMO), methyl formate (MF), H(2)O, and CO). From these observations, it is concluded that several catalytic processes operate simultaneously, and are coupled via common catalytic intermediates. Starting from a P(2)Pd(0) compound formed in situ, oxidation to a palladium imido compound P(2)Pd(II)=NPh, can be achieved by de-oxygenation of nitrobenzene 1) with two molecules of CO, 2) with two molecules of CO and the acidic protons of two methanol molecules, or 3) with all four hydrogen atoms of one methanol molecule. Reduction of P(2)Pd(II)=NPh to P(2)Pd(0) makes the overall process catalytic, while at the same time forming Azo(xy), MPC, DPU and aniline. It is proposed that the Pd-imido species is the central key intermediate that can link together all reduction products of nitrobenzene and all oxidation products of methanol in one unified mechanistic scheme. The relative occurrence of the various catalytic processes is shown to be dependent on the characteristics of the catalysts, as imposed by the ligand structure.
TL;DR: A tetragonal molybdenum nitride (beta-Mo2N) has been prepared by temperature programmed treatment of MoO3 in flowing N-2 + H-2 and for the first time shown to catalyze the liquid phase selective hydrogenation (T = 423 K; P-H2 = 11 bar) of a series of para-substituted (-H, -OH, -O-CH3, -CH 3, -Cl, -I and -NO2) nitrobenzenes to give the corresponding aromatic amine as discussed by the authors
TL;DR: In this article, the transfer of 64 neutral solutes from water and from the gas phase to the solvent benzonitrile has been studied, including ionic species derived from acids by loss of a proton and bases.
TL;DR: Aniline has been successfully produced by catalytic transfer hydrogenation of nitrobenzene in glycerol, which was employed as both a green solvent and a hydrogen donor as discussed by the authors.
TL;DR: In this paper, the coupling of ODE-N with activated carbons catalysts was investigated and two industrially important products, styrene and aniline, were obtained.
TL;DR: It is indicated that efficient adsorption of bulky pharmaceuticals to AC can be achieved by enlarging the adsorbent pore size through suitable activation treatments.
Abstract: Adsorption of sulfapyridine, tetracycline, and tylosin to a commercial microporous activated carbon (AC) and its potassium hydroxide (KOH)-, CO-, and steam-treated counterparts (prepared by heating at 850°C) was studied to explore efficient adsorbents for the removal of selected pharmaceuticals from water. Phenol and nitrobenzene were included as additional adsorbates, and nonporous graphite was included as a model adsorbent. The activation treatments markedly increased the specific surface area and enlarged the pore sizes of the mesopores of AC (with the strongest effects shown on the KOH-treated AC). Adsorption of large-size tetracycline and tylosin was greatly enhanced, especially for the KOH-treated AC (more than one order of magnitude), probably due to the alleviated size-exclusion effect. However, the treatments had little effect on adsorption of low-size phenol and nitrobenzene due to the predominance of micropore-filling effect in adsorption and the nearly unaffected content of small micropores causative to such effect. These hypothesized mechanisms on pore-size dependent adsorption were further tested by comparing surface area-normalized adsorption data and adsorbent pore size distributions with and without the presence of adsorbed antibiotics. The findings indicate that efficient adsorption of bulky pharmaceuticals to AC can be achieved by enlarging the adsorbent pore size through suitable activation treatments.
TL;DR: In this paper, a composite of carboxymethyl-modified β-cyclodextrin-intercalated ZnAl-layered double hydroxide (CMCD-LDH) was investigated for selective adsorption of phenol (Ph) and nitrobenzene (NB).
Abstract: The composite of carboxymethyl-modified β-cyclodextrin-intercalated ZnAl-layered double hydroxide (CMCD-LDH) was investigated for selective adsorption of phenol (Ph) and nitrobenzene (NB). The Freundlich model can be used to describe satisfactorily the adsorption isotherms of Ph and NB. The adsorption capacity of CMCD-LDH for Ph and NB increases with the increase of temperature, indicating the endothermic nature of this sorption process. CMCD-LDH exhibits preferential adsorption for Ph over NB at pH 6.5 due to the selective recognition of the interlayer CMCD cavity. Pseudo-first-order and pseudo-second-order kinetic models were applied to simulate the kinetics of the adsorption process. The calculated qe values based on the pseudo-second-order model are much closer to the experimental data qe,exp. As a result, the pseudo-second-order kinetic model is more reasonable to describe the adsorption process of Ph and NB onto the CMCD-LDH composite. CMCD-LDH can be potentially applied in selective adsorption and separation of wastewater pollutants.
TL;DR: In this paper, a carboxylated multi-walled carbon nanotubes modified glassy carbon (MWCNTs-GC) electrode was fabricated via the drop-casting of a CARNITES suspension onto a glassy electrode.
Abstract: A carboxylated multi-walled carbon nanotubes modified glassy carbon (MWCNTs-GC) electrode was fabricated via the drop-casting of a carboxylated carbon nanotubes suspension onto a glassy carbon electrode. A headspace adsorptive accumulation on the surface of the multi-walled carbon nanotubes modified glassy carbon electrode coupled with cyclic voltammetry has been established for analyzing nitrobenzene and 4-nitrotoluene in water samples. Factors which affect the extraction efficiency (modifier amount, pH, extraction temperature, extraction time, salt addition) have been investigated. The calibration plot for the determination of nitrobenzene and 4-nitrotoluene are linear in the wide ranges of 10–4000 ng mL−1 and 20–6000 ng mL−1 respectively. Under optimal extraction conditions, the detection limits (at S/N = 3) for nitrobenzene and 4-nitrotoluene were 3.0 ng mL−1 and 6.0 ng mL−1 respectively. The proposed method has been applied successfully for the determination of nitrobenzene and nitrotoluene in water and wastewater samples within a recovery range of ca. 97.5–103.33%.
TL;DR: In this paper, two steps involving catalytic hydrogenation of nitrobenzene to phenylhydroxylamine (PHA) in acid medium and its rearrangement to p-aminophenol (PAP) were studied separately in a batch reactor, using a well-characterized 3% Pt/C catalyst.
Abstract: Two steps involving catalytic hydrogenation of nitrobenzene to phenylhydroxylamine (PHA) in acid medium and its rearrangement to p-aminophenol (PAP) were studied separately in a batch reactor, using a well-characterized 3% Pt/C catalyst. The first step of hydrogenation of nitrobenzene to PHA could be carried out at 303 K and a H2 pressure of 0.69 MPa with complete conversion of nitrobenzene, while the achieved selectivity to PHA was higher than 90% with some formation of aniline, even at lower temperature. The second step of PHA rearrangement to PAP could be achieved under a hydrogen atmosphere at elevated temperature of 353 K to give a maximum selectivity to PAP of 74%.
TL;DR: Photocontrollable ONOO(-) generation from a nitrobenzene derivative was demonstrated by the designed compound released NO in response to photoirradiation, and the resulting semiquinone reduced molecular oxygen to generate O(2)˙(-); reaction of the two generated ONOO(-).
TL;DR: In this paper, the influence of the organic solvents and also the effect of some surfactants on the selectivity and transport efficiency of the metal cations through bulk liquid membrane (BLM) was studied.
Abstract: Competitive transport of Zn(II), Cd(II), Cr(III), Co(II), Ag(I), Pb(II), and Cu(II) cations from an aqueous source phase at pH 5 through bulk liquid membrane (BLM) containing 18-crown-6 (ion carrier), organic solvents chloroform, dichloromethane, 1,2-dichloroethane, and nitrobenzene, and chloroform–dichloromethane and chloroform–dichloroethane binary mixed solvents into an aqueous receiving phase at pH 3 has been investigated. The influence of the organic solvents and also the effect of some surfactants on the selectivity and transport efficiency of the metal cations through BLMs were studied. The obtained results show that the selectivity and the efficiency of transport for these heavy metal cations change with the nature of the organic solvents which were used as liquid membranes in these experiments. A good transport efficiency and high selectivity was observed for the Pb(II) cation under the experimental conditions in this investigation.
TL;DR: In this article, the exchange extraction constants corresponding to the general equilibrium M+(aq)+NaL+(nb)⇔ML+(nb)+Na+(aq) taking place in the two-phase water-nitrobenzene system (M+=Li+, Ag+, Rb+, Tl+, Cs+; L=p-tert-butylcalix[4]arene-tetrakis(N,N-diethylacetamide); aq=aqueous phase, nb=nitrogen phase) were determined.
Abstract: Abstract From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium M+(aq)+NaL+(nb)⇔ML+(nb)+Na+(aq) taking place in the two-phase water-nitrobenzene system (M+=Li+, Ag+, Rb+, Tl+, Cs+; L=p-tert-butylcalix[4]arene-tetrakis(N,N-diethylacetamide); aq=aqueous phase, nb=nitrobenzene phase) were determined. Moreover, the stability constants of the ML+ complexes in water-saturated nitrobenzene were calculated; they were found to increase in the cation order Cs+ < Rb+ < Tl+ < Ag+ < Li+.