Nitrophenol Compounds Research Articles

Adsorption of nitrophenol compounds from aqueous solution by cross-linked starch-based polymers

Two kinds of cross-linked starch polymers were synthesized and used as adsorbent materials for the adsorption of o-nitrophenol (o-NP), p-nitrophenol (p-NP), 2,4-dinitrophenol (2,4-DNP) and 2-s-butyl-4,6-dinitrophenol (DNBP) from aqueous solutions. Results from adsorption experiments showed that the polymer 1 prepared by 4,4′-methylene-bis-phenyldiisocyanate (MDI) as cross-linking agent exhibited higher adsorption behaviors than that of the polymer 2 prepared by hexamethylene diisocyanate (HMDI). Equilibrium and thermodynamic of four nitrophenols on polymer 1 were further studied. Analyzed experimental data showed that the Freundlich model fitted the isotherm data better than the Langmuir model of the four nitrophenols onto polymer 1. The thermodynamics for the adsorption of the nitrophenols on polymer 1 were estimated in the range of 303–333 K. It has been found that the values of Gibbs free energy (ΔG) became more negative with decreasing temperature, which indicated that the adsorption process was more favorable at low temperature.

Determination of nitrophenolic compounds from atmospheric particles using hollow‐fiber liquid‐phase microextraction and capillary electrophoresis/mass spectrometry analysis

A hollow-fiber liquid-phase microextraction method was developed to enrich nine nitrophenolic compounds from aqueous extracts of atmospheric aerosol particles. Analysis was performed by CE coupled with ESI MS. The BGE composition was optimized to a 20 mM ammonium acetate buffer at pH 9.7 containing 15% methanol v/v. Several extraction parameters (composition of organic liquid membrane, pH of acceptor phase, salting-out effect, extraction time) were investigated for their effect on the analyte recoveries. The donor phase consisted of a 1.8 mL sample solution kept at pH 2 while the acceptor phase was a 15 μL 100 mM aqueous ammonia solution. Dihexyl ether served as supported liquid membrane. Low detection limits in the range of nanomole per liter were achieved. Recoveries of aqueous standard solutions were found to be between 11 and 90% with enrichment factors between 10 and 100. Interday and intraday repeatabilities were in an acceptable range for most compounds (6-15% and 7-10%, respectively) but somewhat higher for 4-nitrocatechol (59 and 48%) and 2-nitrophenol (17 and 35%). The developed method was found to be competitive with more established method and was successfully applied to samples of atmospheric particulate matter from field experiments.

PEI@Mg2SiO4: an efficient carbon dioxide and nitrophenol compounds adsorbing material

PEI@Mg2SiO4: an efficient carbon dioxide and nitrophenol compounds adsorbing material.

Covalent fabrication of methyl parathion hydrolase on gold nanoparticles modified carbon substrates for designing a methyl parathion biosensor

A biosensor based on AuNP modified GC electrodes has been developed for direct detection of methyl parathion. AuNP can be introduced to mixed monolayers of aryldiazonium salt modified GC electrodes by Au–C bonding through aryldiazonium salt chemistry, which provides a stable interface showing efficient electron transfer between biomolecules and electrodes. PEG molecules were introduced to the interface to resist non-specific protein adsorption. AuNP surfaces were further modified with 4-carboxyphenyl followed by covalent immobilization of methyl parathion hydrolase (MPH), a specific biocatalytic enzyme to methyl parathion. Exposure of this interface to methyl parathion resulted in a change in amperometric signal due to the MPH catalytic hydrolysis of methyl parathion producing electroactive compound 4-nitrophenol. This biosensor shows high selectivity, specificity, reproducibility and stability, and is functional for the detection of methyl parathion in real samples. The linear range for detection of methyl parathion is 0.2–100ppb with a detection limit of 0.07ppb in 0.1M phosphate buffer at pH 7.0.

A novel magnetic Fe@Au core–shell nanoparticles anchored graphene oxide recyclable nanocatalyst for the reduction of nitrophenol compounds

In this study, a novel catalyst based on Fe@Au bimetallic nanoparticles involved graphene oxide was prepared and characterized by transmission electron microscope (TEM), and x-ray photoelectron spectroscopy (XPS). The nanomaterial was used in catalytic reductions of 4-nitrophenol and 2-nitrophenol in the presence of sodium borohydride. The experimental parameters such as temperature, the dosage of catalyst and the concentration of sodium borohydride were studied. The rates of catalytic reduction of the nitrophenol compounds have been found as the sequence: 4-nitrophenol>2-nitrophenol. The kinetic and thermodynamic parameters of nitrophenol compounds were determined. Activation energies were found as 2.33 kcal mol−1 and 3.16 kcal mol−1 for 4-nitrophenol and 2-nitrophenol, respectively. The nanomaterial was separated from the product by using a magnet and recycled after the reduction of nitrophenol compounds. The recyclable of the nanocatalyst is economically significant in industry.

Molecular modeling and spectral comparison for the change in methyl position of nitrophenol compounds 2-methyl-4-nitrophenol and 3-methyl-4-nitrophenol: A density functional theoretical study

FT-IR and FT-Raman spectra of 2-methyl-4-nitrophenol (PNOC) and 3-methyl-4-nitrophenol (PNMC) were recorded and analyzed in the solid phase in the region 4000–400cm−1 and 3500–50cm−1 respectively. Molecular modeling of the compounds PNOC and PNMC were done by the density functional theoretical (DFT) method using Becke’s three parameter exchange functional combined with the Lee–Yang–Parr correlation functional with 6-31G(d) as basis set. Vibrational assignments of the two compounds have been carried out with the help of Normal coordinate analyses (NCA) followed by the Scaled Quantum Mechanical Force Field calculations (SQMFF). Intra-molecular charge transfer and delocalization within the molecule is confirmed with the aid of natural bond orbital analysis (NBO). PNOC and PNMC are similar compounds with same functional groups, only the position of the methyl group is different. The effect of the position change of the methyl group was interpreted with the vibrational spectra.

Physicochemical properties and trace organic compounds in a dairy processor’s aerobic bioreactor

Wastewater samples were taken from an aerobic bioreactor, operated by a dairy processor in southeastern Australia to reduce nutrient and pollutant loads. Samples were taken over a two-year period, to determine whether trace organic compounds or physicochemical analyses of the wastewater could be used to discriminate the water taken before, during and after processing of the wastewater in the bioreactor. Multivariate analyses of the physicochemical data suggested that nitrate, pH and total dissolved nitrogen best described the infeed wastewater entering the bioreactor, while organic and particulate phosphorus concentrations where predominantly responsible for describing the composition of the content of the bioreactor. Gas chromatography–mass spectrometry data of organic compounds within the wastewater samples were also analysed via multivariate analyses. The analyses found that the compound 4-nitrophenol was associated with ammonia concentrations and mixed liquor wastewater. Therefore, 4-nitrophenol may possibly be used to act as an indicator of anaerobicity in aerobic bioreactors.

Degradation of trace nitrobenzene in water by microwave-enhanced H2O2-based process

To evaluate possible use of microwave-enhanced H2O2-based (MW/H2O2) process to degrade trace nitrobenzene (NB) in water, a series of batch experiments were conducted. The results showed that 2450MHz microwave irradiation significantly enhanced oxidative decomposition of nitrobenzene (NB) in a H2O2 system. About 90% NB was degraded by the MW/ H2O2 process in 30 min. Moreover, the MW/ H2O2 process could enhanced the oxidative degradation of NB even at relatively low temperature (50°C). When the initial concentration of NB was 300μg/L, the optimum ratio of H2O2 to NB and MW power were 70 and 300W respectively. The presence of humic acid significantly increased H2O2 dosage. The ultraviolet absorbance at 254 nm (UV254) indicated degradation of NB was stepwise and some intermediates were produced. The gas chromatography-mass spectrometric (GC-MS) analysis showed that main intermediates were nitrophenolic and carbonyl compounds.

Biodegradation of nitrophenol compounds and the membrane fouling trends in different submerged membrane bioreactors

Abstract Phenolic compounds are commonly used in industry and discharged into water. The objectives of this study were to evaluate the performance of submerged membrane bioreactors (MBRs) to simultaneously remove nitrophenols (metabolic uncouplers) and inorganic nitrogen compounds from wastewater and to determine the membrane fouling trends in two different types of MBRs: CSTR-MBR (continuous stirred tank reactor MBR) and MLE-MBR (modified Ludzack Ettinger MBR). At a target solids retention time of 110 day, a mixture of nitrophenol compounds (2-nitrophenol, 3-nitrophenol, 4-nitrophenol, and 2,4-dinitrophenol) was continuously dosed to the MBRs at the influent concentrations of 0.05 mM each. The nitrophenol removal efficiencies ranged from 87% to 96% while the total inorganic nitrogen removal efficiencies were 52% and 75% for the CSTR-MBR and MLE-MBR, respectively. The metabolic uncoupling by nitrophenols resulted in lower adenosine triphosphate (ATP) yield of 0.06 mg/g VSS and bound extracellular polymeric substances (EPS) of 20.5 mg/g VSS from the CSTR-MBR compared to the values of 0.10 mg ATP/g VSS and 30.7 mg EPS/g VSS from the MLE-MBR. There was a direct relationship between the EPS content and fouling, as membranes were less susceptible to fouling in the CSTR-MBR because of the reduced release of EPS due to the metabolic uncoupling by nitrophenols. These results suggest that both MBRs are effective in removing nitrophenols. While the MLE operation resulted in more efficient nitrogen removal, the CSTR-MBR configuration appears to be superior with less membrane fouling, an added benefit to the CSTR process, which is capable of reducing the toxicity of chemicals due to rapid mixing and dilution and widely used in industrial operations.

Discovery of nitrophenols as GPR35 agonists

GPR35 is a family A orphan G protein-coupled receptor whose biological functions are largely unknown. Identification of novel GPR35 ligands is essential to elucidate the biology and pathophysiology of GPR35. Here we report the discovery of nitrophenol compounds to be a novel chemical class of GPR35 agonists. Both endogenously and stably expressed GPR35 were found to be activated by a number of nitrophenol analogues including 2-amino-4,6-dinitrophenol, tolcapone and nitecapone. Among them, 4,4′-(2,2-dichloroethene-1,1-diyl)bis(2,6-dinitrophenol) was found to be the most potent GPR35 agonist.

Antipassivating Electrochemical Process of Glassy Carbon Electrode (GCE) Dedicated to the Oxidation of Nitrophenol Compounds

AbstractWe report for the first time a novel electrochemical treatment applied to a glassy carbon electrode (GCE) during p‐nitrophenol (PNP) oxidation and dedicated to the limitation of electrode passivation by nitrophenol compounds oxidation. We propose an electrochemical process of direct phenol oxidation by starting the electrolysis at a very low potential, −1.2 V/SCE, in order to generate a soluble monomer, p‐aminophenol, on the electrode surface. Then, p‐aminophenol elaborated on the electrode surface in the place of oligomers, gives benzoquinone as a by‐product and no film formation was observed. Furthermore, the presence of a p‐NiTSPc (film of nickel tetrasulfonated phtalocyanine) coating permitted to increase two times the electrode sensitivity without passivation, too.

Amperometric detection at carbon felt electrodes. Application to the determination of nitro musk derivatives and phenolic endocrine disruptors

The use of a carbon-felt electrode (CFE) of small dimensions for the amperometric detection of various nitro musk fragrances and phenolic compounds with endocrine disrupting properties is reported. The electrode material is composed of multiple disordered carbon fibres of micrometre diameter. The use of CFE for the detection of nitro musk derivatives implied the electrochemical activation by applying successive SW voltammetric scans between 0.0 and +2.6 V vs. Ag/AgCl in 0.1 M PBS of pH 7.0. At the activated CFE (aCFE), cyclic voltammograms for nitro musks derivatives in 0.1 M PBS of pH 7.0, showed a non-reversible behaviour with two or three cathodic peaks corresponding to the number of nitro groups present in the molecule. Hydrodynamic voltammograms from nitro musk solutions obtained under flow injection conditions at the aCFE led to the selection of a cathodic potential of −800 mV vs. Ag/AgCl as the value to be applied for the amperometric detection of these compounds. A calibration graph for musk ketone was obtained between 0.1 and 10 μg mL−1 with a detection limit of 50 ng mL−1. A RSD value of 3.7% was calculated for 10 successive measurements of 500 ng mL−1 musk ketone with no need for cleaning the electrode surface. Similar results to those obtained by GC-MS were found for the analysis of incense samples by FI with amperometric detection at the activated CFE. FI hydrodynamic voltammograms for estrogenic phenols at non-activated CFE exhibited current anodic plateaux from which a detection potential of +700 mV was chosen. Liquid chromatography with amperometric detection at the CFE was accomplished to analyze mixtures of estrogenic compounds. A mobile phase consisting of 40 : 60 (v/v) acetonitrile : 0.05 M PBS of pH 7.0 was employed. Detection limits ranging between 102 nM for bisphenol A (BPA) and 182 nM for 17α-ethynylestradiol (EE2) were achieved. Good recoveries were obtained in the analysis of well water and tap water samples spiked with five phenolic estrogenic compounds at a 14 nM each concentration level.

ADSORPTION OF 2,4-DINITROPHENOL AND 2,6-DINITROPHENOL ONTO ORGANOCLAYS AND INORGANIC-ORGANIC PILLARED CLAYS

The adsorption of two substituted nitrophenols, 2,4-dinitrophenol and 2,6-dinitrophenol on smectite clay modified by intercalation of hexadecylpyridinium bromide (O-Sa01) or hexadecylpyridinium bromide and complex hydroxy-aluminum (IO-Sa01) were studied. The adsorption experiments were conducted in batch mode. The results obtained show that adsorption increases with the initial concentration of the nitrophenols and equilibrium is reached within a short period of time (20 min). The maximum capacity uptake from waste water was 28.07 and 28.58 mg g-1 for O-Sa01 and IO-Sa01 respectively for an initial concentration of 18.40 mg L-1 of 2,4-dinitrophenol, and 24.65 and 26.62 mg g-1 of 2,6-dinitrophenol for O-Sa01 and IO-Sa01, respectively, for the same initial concentration as in the case of 2,4-dinitrophenol. Separation factor RL indicates that the adsorption of the nitrophenol compounds studied is more favorable on IO-Sa01. Adsorption was modeled by the equations of Langmuir, Freundlich, and Temkin. Kinetic data were described by the pseudo-first order and pseudo-second order equations. Based on the linear correlation coefficient (>0.97), the Langmuir model better represented the data.

Adsorption and Competitive Adsorption on Zeolites of Nitrophenol Compounds Present in Wastewater

This work investigates the removal of various nitrophenolic compounds (ortho-nitrophenol (ONP), para-nitrophenol (PNP), meta-nitrophenol (MNP), and 2,4-dinitrophenol (2,4-DNP)) from aqueous solution using hydrophobic FAU zeolites. The adsorption equilibrium of nitrophenols from aqueous solutions by FAU can be well-described using the Fowler−Guggenheim equation. The relative affinity of nitrophenols toward the FAU is dependent on the pH solution and on the pollutant solubility in water. Their sorption capacity is in the following order: ONP > 2.4-DNP > PNP > MNP. In binary mixtures, the most important parameter that governs the adsorption in zeolites seems to be the solubility of pollutants in water. Thus, the less-soluble compound (in this case, ONP) was adsorbed more easily than the other components present in the binary mixture. Finally, hydrophobic FAU zeolite seems to be an efficient adsorbent; it is able to be easily regenerated under air or by solvent leaching, through retention of these initial ads...

Assessment of a dynamic hollow-fibre liquid phase microextraction system for human blood plasma samples

A dynamic liquid phase microextraction (LPME) system, based on hollow-fibre supported liquid membrane (SLM) extraction, was developed for extracting ionisable xenobiotics from human plasma, and its performance was evaluated (in terms of extraction efficiency, reproducibility, durability and carry-over) using nitrophenolic compounds as model analytes at concentrations of 0.1–0.5 μg mL −1 in aqueous standards. The efficiency and repeatability were tested also on spiked human plasma. The system is non-expensive, convenient, requires minimal manual handling and enables samples with volumes as small as 0.2 mL to be extracted. For plasma samples extraction efficiencies of between 30 and 58% were achieved within 20 min, including washing steps. The limit of detection (LOD) values were in the range 0.02–0.03 μg mL −1. The developed system can provide enrichment factors up to eight, based on the injection-to-acceptor volume ratio (in this case 0.2–0.025 mL). The same hollow-fibre membrane was used up to 8 days with no loss of efficiency. Carry-over was lower than detection limit.

Real‐Time Nitrophenol Detection Using Single‐Walled Carbon Nanotube Based Devices

AbstractSingle‐walled carbon nanotube (SWNT) based devices have been developed for the real‐time detection of nitrophenols in aqueous solution. SWNTs are assembled to electrodes using AC dielectrophoresis technique. The SWNT devices exhibit not only high sensitivity to nitrophenol compounds, but also good reusability. Charge transfer between nitro group and SWNTs, and the metal‐nanotube interface modification are hypothesized to be the possible origins of conductance change. These results indicated that the SWNT devices can be utilized as a simple, low cost, sensitive, and reusable platform for real‐time detection of nitrophenol compounds.

The Electrochemical Reduction of Nitrophenols on Silver Globular Particles Electrodeposited under Pulsed Potential Conditions

A pulsed electrodeposition technique based on a multipulse sequence of potentials of equal amplitude, duration and polarity was employed for the preparation of highly dispersed silver particles on glassy carbon surfaces . A detailed analysis of the scanning electron microscope images reveals that silver deposit, obtained under pulsed electrodeposition conditions, appears as homogeneously compact and the crystallites are well dispersed on the GC substrate. The globular particles appear isolated or dispersed as twinned and rarely as trimer islands. The resulting silver modified electrode was electrochemically characterized through the reduction of nitrophenol compounds. The potential needed for the reduction of these compounds on the electrodes is significantly less negative than that observed on the unmodified glassy carbon electrode or bare silver substrates. Under chronoamperometric conditions, the Ag electrodeposited film shows a good catalytic activity and temporal stability regarding the electroreduction of nitrophenol compounds and can be usefully used for the electrochemical massive hydrogenation of these molecules in acidic medium. Moreover, the electrode was successfully tested as a sensing probe for the analytical detection of nitrophenol compounds under differential pulse voltammetric conditions showing interesting analytical performance in terms of limits of detection and dynamic linear range.

Identification and Biological Evaluation of a Novel and Potent Small Molecule Radiation Sensitizer via an Unbiased Screen of a Chemical Library

For patients with solid tumors, the tolerance of surrounding tissues often limits the dose of radiation that can be delivered. Thus, agents that preferentially increase the cytotoxic effects of radiation toward tumor cells would significantly alter the therapeutic ratio and improve patient survival. Using a high-throughput, unbiased screening approach, we have identified 4'-bromo-3'-nitropropiophenone (NS-123) as a radiosensitizer of human glioma cells in vitro and in vivo. NS-123 radiosensitized U251 glioma cells in a dose-dependent and time-dependent manner, with dose enhancement ratios ranging from 1.3 to 2.0. HT-29 colorectal carcinoma and A549 lung adenocarcinoma cells were also radiosensitized by NS-123 in vitro, whereas NS-123 did not increase the radiation sensitivity of normal human astrocytes or developmental abnormalities or lethality of irradiated Zebrafish embryos. In a novel xenograft model of U251 cells implanted into Zebrafish embryos, NS-123 enhanced the tumor growth-inhibitory effects of ionizing radiation (IR) with no apparent effect on embryo development. Similar results were obtained using a mouse tumor xenograft model in which NS-123 sensitized U251 tumors to IR while exhibiting no overt toxicity. In vitro pretreatment with NS-123 resulted in accumulation of unrepaired IR-induced DNA strand breaks and prolonged phosphorylation of the surrogate markers of DNA damage H2AX, ataxia telangiectasia mutated protein, DNA-dependent protein kinase, and CHK2 after IR, suggesting that NS-123 inhibits a critical step in the DNA repair pathway. These results show the potential of this cell-based, high-throughput screening method to identify novel radiosensitizers and suggest that NS-123 and similar nitrophenol compounds may be effective in antiglioma modalities.

Kinetics of the electrochemical oxidation of 2-nitrophenol and 4-nitrophenol studied by in situ UV spectroscopy and chemometrics

Here we report on the elimination of 4-nitrophenol (4-NPh) and 2-nitrophenol (2-NPh) from aqueous solutions by electrochemical oxidation at the dimensionally stable anodes (DSA) Ti/IrO 2–SnO 2–Sb 2O 5. The ternary oxide electrodes show high catalytic activity for the electrochemical oxidation of nitrophenolic compounds. UV–vis spectroscopy was employed to in situ monitor time-dependent concentration changes during the electrochemical oxidation of the 2-NPh and 4-NPh. A kinetic analysis of the electrochemical oxidation of 2-NPh, 4-NPh and a mixture of the two has been carried out. The electrochemical oxidation of 4-NPh and 2-NPh is governed by the hydroxyl radical reaction and obeys the first-order kinetics with the overall apparent activation energy of 8.3 and 9.2 kJ mol −1, respectively. Partial least squares (PLS) regression was performed to resolve the highly overlapping spectrophotometric signals measured from the mixture of 4-NPh and 2-NPh. In situ UV–vis spectroscopic measurements in combination with PLS multivariate calibration enabled us to determine the competitive effects during the electrochemical treatment of variety of mixtures of 2-NPh and 4-NPh, showing that the presence of 2-NPh inhibits the electrochemical oxidation of 4-NPh.

A microcosm study on bioremediation of fenitrothion-contaminated soil using Burkholderia sp. FDS-1

Abstract Fenitrothion, a toxic organophosphorus pesticide, can build up the concentration of nitrophenolic compound in soils and hence needs to be removed. Burkholderia sp. FDS-1, a fenitrothion-degrading strain, was used in this work to study factors affecting its growth, and then evaluated for its capacity to degrade fenitrothion in soil microcosms. Minimal salt medium containing 1% (w/v) glucose was found to be a suitable carbon source for inoculum preparation. Various factors, including soil pH, temperature, initial fenitrothion concentration, and inoculum size influenced the degradation of fenitrothion. Microcosm studies performed with varying concentrations (1–200 mg kg−1) of fenitrothion-spiked soils showed that strain FDS-1 could effectively degrade fenitrothion in the range of 1–50 mg kg−1 soil. The addition of Burkholderia sp. FDS-1 at 2×106 colony forming units g−1 soil was found to be suitable for fenitrothion degradation over a temperature range of 20–40 °C and at a slight alkaline pH (7.5). The results indicate that strain FDS-1 has potential for use in bioremediation of fenitrothion and its metabolite-contaminated sites. This is a model study that could be used for decontamination of sites contaminated with other compounds.