Nitroaromatics In Water Research Articles

Aggregation-induced emission active multianalyte sensor: Detection of pH, carbonate, bi-carbonate and nitroaromatics in water

An aggregation-induced emission (AIE) based multi-tasking probe DAAQ (5-(dimethylamino)-N-(9,10-dioxo-9,10-dihydroanthracen-2-yl)naphthalene-1-sulfonamide) has been reported for detecting multiple analytes such as anions (carbonate and bicarbonate ions) and nitroaromatic compounds (2,4-DNP and TNP). Probe DAAQ displayed the photophysical properties of aggregation-induced emission (AIE) in DMSO-water mixture, acidochromism and detected various analytes, making DAAQ a multi-tasking probe. DAAQ respond to carbonate and bicarbonate (CO32− and HCO3−) with a colour change from pale yellow to dark orange. The limit of detections (LOD) was estimated as 0.486 mg/L and 41.35 mg/L for CO32− and HCO3−, respectively. The applications of DAAQ were also explored to detect CO32− ions in water samples collected from various sources and soft drinks. Further, the probe also explored detecting neural aromatic compounds such as 2,4-DNP and TNP by a naked eye colour change and the LODs were calculated as 12.6 µM and 8.19 µM, respectively. DFT calculations were applied for the confirmation binding studies of DAAQ with multiple analytes. The sensing of 2,4-DNP and TNP were achieved through PET with a Turn-Off response. The sensing mechanisms were confirmed with 1H NMR experiments.

Flower-like MoS2 microspheres highly dispersed on CoFe2O4/MIL-101(Fe) metal organic framework: a recoverable magnetic catalyst for the reduction of toxic nitroaromatics in water

In this study, we report on the synthesis and characterization of novel magnetic MoS2/CoFe2O4/MIL101-(Fe) nanocomposite catalysts designed for the efficient reduction of toxic nitroaromatic compounds, such as nitrophenols and nitroanilines,...

Anthracene and tetraphenylsilane based conjugated porous polymer nanoparticles for sensitive detection of nitroaromatics in water

Conjugated porous polymers (CPPs) are a kind of promising sensing materials for the detection of nitroaromatic compounds, but their sensing applications in aqueous media are limited because of their poor dispersity or solubility in water. In this study, we prepared anthracene and tetraphenylsilane based CPPs named PSiAn by conventional Suzuki coupling and Suzuki-miniemulsion polymerization, respectively. The structure, morphology and porosity of the CPPs were characterized by Fourier Transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H NMR), transmission electron microscope (TEM) and N2 sorption isotherm, respectively. Both of the CPPs have porous structure which is beneficial for the adsorption and diffusion of the analytes within them. The particle size of PSiAn nanoparticles prepared by Suzuki-miniemulsion polymerization is 10–40 nm from the TEM image, which facilitates the dispersion in the aqueous phase. Combined with the porosity and nanoparticle morphology, PSiAn nanoparticles realized the efficient photoluminescence (PL) sensing of nitroaromatic explosives in aqueous phase. The limit of detection (LOD) and limit of quantitation (LOQ) of PSiAn nanoparticles for 2,4,6-trinitrophenol (TNP) detection in the pure aqueous phase are 0.33 μM and 1.11 μM, respectively. Meanwhile, the good selectivity and anti-interference in presence of other nitro-compounds were observed. Furthermore, the spike/recovery test for the TNP detection in real water samples by PL sensing based on PSiAn nanoparticles indicates the quantitative recovery of TNP from 100.74 % to 101.00 %. The electrochemical test, ultraviolet–visible absorption spectra, excitation and emission spectra, and time-resolved PL spectra were investigated to explore the PL sensing mechanism. As a result, it is found that the fluorescence inner filter effect might be the predominant quenching mechanism during the detection of nitrophenolic compounds such as TNP and 4-nitrophenol (4-NP).

Surfactant-free synthesis of Ag@TiO2 and CuO@TiO2 photocatalyst: a comparative study of their photocatalytic activity for reduction of nitroaromatics in water

The reduction of harmful nitroaromatics to useful amino-aromatics have significant opportunities in synthetic chemistry. Here a visible-light-driven eco-friendly method for the selective reduction of aromatic nitro compounds to their corresponding amines in aqueous solution by using Ag@TiO2 and CuO@TiO2 is described. It was observed that both Ag@TiO2 and CuO@TiO2 are photo-catalytically more efficient compared to bare TiO2 and CuO@TiO2 has higher activity over Ag@TiO2 for the said conversion. The structural and morphological characterization of the as-synthesized catalysts has been done with SEM-EDX, TEM, powder XRD, ICP-AES, XPS, Photoluminescence, and UV-vis spectroscopic techniques. The nanocomposites Ag@TiO2 and CuO@TiO2 exhibit pure anatase phase with average crystallite size of 5.89 nm and 5.87 nm respectively as calculated from the Debye-Scherrer equation depending on the (101) plane. UV-visible results inferred enhanced optical properties of both the synthesized catalysts and revealed a reduced band gap (3.07 eV for Ag@ TiO2 and 2.5 eV for CuO@ TiO2) as compared to neat TiO2 (3.36 eV). Various nitro compounds were tolerated under 150 W LED as a light source (13.9 lumens for an area of 0.2 ft2) in an aqueous medium at room temperature (30 °C) using NaBH4 as a reducing agent to access corresponding amines in satisfying yields (78%–99%). The catalyst can be separated from the reaction mixture by simple centrifugal precipitation and reused for up to six consecutive cycles without apparent loss of its catalytic activity. The products were characterized by 1H-NMR spectroscopic techniques and compared with authentic samples.

Highly stable and uniform colloidal silver quantum dots stabilized with (N,S,O) donor ligand: Selective sensing of Hg(II)/Cu(II) and I− ions and reduction of nitro-aromatics in water

The present paper showed the role of ligand inthe effective stabilization of colloidal silver-quantum dots (Ag-QDs) and their applications for the colorimetric detection of metal ions/anions. Furthermore, the Ag-QDs have been explored to reduce nitroaromatics, industrial waste and pollutants. The donor atoms such as (N,S,O) present on ligands have been found to stabilize the Ag-QDs in the colloidal state effectively, and the pendant alkyl chain governs their uniform dispersion. The QDs (size ∼ 5 nm) are highly stable and can be kept in the colloidal state without aggregation for months under ambient conditions. The Ag-QDs showed naked-eye colorimetric sensing of Hg(II)/Cu(II) and I− ions selectively over other ions at very low concentrations. The colorimetric change has been attributed due to cation and anion-mediated aggregation of QDs. Furthermore, these QDs have also been found effective for reducing various nitroaromatics into valuable amines in a very short time and showed first-order kinetics with the calculated rate of 0.1352 min−1. The Hammett plot suggests that the reaction rate depends on the groups present at the para-position to the nitro group with a negative slope of − 1.291 which indicates that the reaction is proceedingviathe formation of a cationic intermediate. The results described in this paper will be the pioneer in the field of designing of new ligands for the effective stabilization of metal nanoparticles in the colloidal state without altering their activity.

Phosphorous‐modified Porous Carbon Supported Nickel Nanoparticles as a Catalyst for the Reduction of Nitroaromatics in Water

AbstractPhosphorus‐modified porous carbon (PCP) with about 7 w% phosphorus content has been prepared from acetylene and triphenylphosphine using chemical vapor deposition method. Then, 5, 10, 15, 20, 25, and 30 w% nickel(0) nanoparticles have been deposited (using the in‐situ reduction of NiCl2 salt) on the surface of PCP to obtain Ni‐decorated PCP (NPCP). The prepared materials (NPCP) have been employed as a catalyst for the catalytic reduction of nitrobenzene derivatives to anilines. The NPCP with 20 w% of Ni showed the highest catalytic efficiency. The reaction was carried out using 10 mg catalyst, 2 mL of 25 % hydrazine hydrate solution as the reducing agent in 2 h (optimized conditions) to obtain the product in 51–100 % yield. To show the versatility of this method, 8 nitrobenzene derivatives (including 3 different nitrophenols) have been successfully reduced using this method. The recyclability of the catalyst was investigated and the results showed only 20 % decreasing in the yield after 6 runs.

Chemoselective reduction of nitroaromatics using recyclable alumina-supported nickel nanoparticles in aqueous medium—exploration to one pot synthesis of benzimidazoles

An economical and eco-compatible synthetic protocol for chemoselective and regioselective reduction of nitroaromatics in water has been achieved using easily accessible alumina-supported nickel nanoparticles as a stable recyclable heterogeneous catalyst. Various sensitive substituents like allyloxy, benzyloxy, t-butyldimethylsilyloxy, hydroxymethyl, alkoxycarbonyl, formyl, keto, carboxylic acid, chloro, bromo, azo and cyano were tolerated in the aforesaid protocol. This method has been extended for the construction of imidazole derivatives through one-pot reductive condensation of 2-nitroaniline with diversely substituted benzaldehydes. Some of the synthesized imidazoles have been used as antibacterial, antiplatelet and antithrombotic agents.

Assembly of a rod indium–organic framework with fluorescence properties for selective sensing of Cu2+, Fe3+ and nitroaromatics in water

A chiral fluorescent In-MOF with two types of unique homochiral In–O–In helical chains was synthesized. Then it was developed as a highly sensitive fluorescence sensor for detecting Cu2+, Fe3+ and nitroaromatics in water.

Modification of cellulose filter paper with bimetal nanoparticles for catalytic reduction of nitroaromatics in water

Modification of cellulose filter paper with bimetal nanoparticles for catalytic reduction of nitroaromatics in water

Copper oxide\u2013graphene oxide nanocomposite: efficient catalyst for hydrogenation of nitroaromatics in water

A low-cost nanocomposite catalyst containing copper oxide (CuO) nanoparticles (NPs) on graphene oxide (GO) was fabricated by a facile hydrothermal self-assembly process. The segregated CuO NPs and GO exhibited negligible catalytic activities for the reduction of nitroaromatics. However, their hybrid composite accomplished facile reduction with high conversions for several substituted nitroaromatics in aqueous NaBH4 solution; synergetic coupling effect of CuO NPs with GO in the nanocomposite catalyst provided excellent catalytic activity. The nanocomposite catalyst could be separated from the reaction mixture and recycled consecutively.

Recent Advances in the Nanocatalysts-assisted NaBH4 Reduction of Nitroaromatics in water.

In view of the increasing applications of nanocatalysis in chemical transformations, this article illustrates recent advances on the use of nanocatalysts for an important reduction reaction, the hydrogenation of nitroaromatics to significant aminoaromatics with aqueous NaBH4 solution; the utility of mono- and multimetal nanocatalysts with special emphasis on heterogeneous nanocatalysts is included. A progressive trend on the applicability of nanocatalysts is also incorporated with large-scale application and their sustainable recyclization and reuse utilizing supported and magnetic nanocatalysts; representative methods for the synthesis of such reusable nanocatalysts are featured.

Fluorescent Amorphous Distyrylnaphthalene-Based Polymers: Synthesis, Characterization and Thin-Film Nanomolar Sensing of Nitroaromatics in Water.

Two new fluorescent segmented conjugated polymers with either 1,4- or 2,6-distyrylnaphthalene chromophores and their model compounds were synthesized and the chemosensing abilities of the polymeric thin films to detect nitroaromatics (NACs) in aqueous media were evaluated. The structural, thermal and optical properties of the polymers were correlated with those displayed by their corresponding model compounds. Changes in the connectivity of naphthylene units caused minor differences in optical properties, morphology and quenching efficiencies. Molecular modeling highlighted the extremely bent character of polymer microstructures that explains their high solubility and amorphous character. Polymeric films are amorphous, strongly fluorescent and showed remarkable quenching efficiencies in the nanomolar range with picric acid (PA) and trinitrotoluene (TNT). Quenching experiments using either different nitroaromatic quenchers, excitation wavelengths, excitation beam path-lengths, or time of exposure of the film to the quenching solution evidenced the dominant role of inner filter effects (IFE) in the polymer response to NACs in the micromolar range. The sensing response towards PA, a quencher that strongly absorbs at the excitation wavelength, has an IFE contribution even at the nanomolar range, while the response towards the non-absorbing TNT depends only on the quenching occurring after diffusion of the analyte into the film.

A supramolecular Tröger's base derived coordination zinc polymer for fluorescent sensing of phenolic-nitroaromatic explosives in water.

A V-Shaped 4-amino-1,8-napthalimide derived tetracarboxylic acid linker (L; bis-[N-(1,3-benzenedicarboxylic acid)]-9,18-methano-1,8-naphthalimide-[b,f][1,5]diazocine) comprising the Tröger's base (TB) structural motif was rationally designed and synthesised to access a nitrogen-rich fluorescent supramolecular coordination polymer. By adopting the straight forward precipitation method, a new luminescent nanoscale Zn(ii) coordination polymer (TB-Zn-CP) was synthesized in quantitative yield using Zn(OAc)2·2H2O and tetraacid linker L (1 : 0.5) in DMF at room temperature. The phase-purity of as-synthesised TB-Zn-CP was confirmed by X-ray powder diffraction analysis, infra-red spectroscopy, and elemental analysis. Thermogravimetric analysis suggests that TB-Zn-CP is thermally stable up to 330 °C and the morphological features of TB-Zn-CP was analysed by SEM and AFM techniques. The N2 adsorption isotherm of thermally activated TB-Zn-CP at 77 K revealed a type-II reversible adsorption isotherm and the calculated Brunauer-Emmett-Teller (BET) surface area was found to be 72 m2 g-1. Furthermore, TB-Zn-CP displayed an excellent CO2 uptake capacity of 76 mg g-1 at 273 K and good adsorption selectivity for CO2 over N2 and H2. The aqueous suspension of as-synthesized TB-Zn-CP showed strong green fluorescence (λmax = 520 nm) characteristics due to the internal-charge transfer (ICT) transition and was used as a fluorescent sensor for the discriminative sensing of nitroaromatic explosives. The aqueous suspension of TB-Zn-CP showed the largest quenching responses with high selectivity for phenolic-nitroaromatics (4-NP, 2,4-DNP and PA) even in the concurrent presence of other potentially competing nitroaromatic analytes. The fluorescence titration studies also provide evidence that TB-Zn-CP detects picric acid as low as the parts per billion (26.3 ppb) range. Furthermore, the observed fluorescence quenching responses of TB-Zn-CP towards picric acid were highly reversible. The highly selective fluorescence quenching responses including the reversible detection efficiency make the nanoscale coordination polymer TB-Zn-CP a potential material for the discriminative fluorescent sensing of nitroaromatic explosives.

Syntheses and structures of two gold(I) coordination compounds derived from P-S hybrid ligands and their efficient catalytic performance in the photodegradation of nitroaromatics in water.

Solvothermal reactions of HAuCl4·4H2O with a P-S hybrid ligand N,N-bis(diphenylphosphanylmethyl)-amino-thiocarbamide (dppatc) at 80 °C and 115 °C produced two Au-P-S complexes, [Au2(dppatc)2]Cl2 (1) and [Au2(dppmt)2]n (2) (dppmtH = (diphenylphosphino)methanethiol). 1 and 2 were characterized by elemental analyses, IR and UV-vis spectra, thermal-gravity analyses, powder X-ray diffraction and single crystal X-ray diffraction analyses. Compound 1 contains a dinuclear [Au2(dppatc)2](2+) dication, while 2 has a one-dimensional chain formed by AuAu aurophilic interactions. Compounds 1 and 2 exhibited excellent catalytic activity toward the photodegradation of nitrobenzene, p-nitrophenol and 2,4-dinitrophenol in aqueous solutions. The degradation reactions followed the zero-order kinetic model, in which the three nitroaromatics could be converted into CO2 and H2O in 92-96% yields.

ChemInform Abstract: Chemoselective Reductions of Nitroaromatics in Water at Room Temperature.

A robust and green protocol for the reduction of functionalized nitroarenes to the corresponding primary amines has been developed. It relies on inexpensive zinc dust in water containing nanomicelles derived from the commercially available designer surfactant TPGS-750-M. This mild process takes place at room temperature and tolerates a wide range of functionalities. Highly selective reductions can also be achieved in the presence of common protecting groups.

Efficient Thermal- and Photocatalyst of Pd Nanoparticles on TiO2 Achieved by an Oxygen Vacancies Promoted Synthesis Strategy

Pd nanoparticles supported on defective TiO2 with oxygen vacancies (TiO2-OV) have been prepared by an oxygen vacancies mediated reduction strategy. The resulting Pd-TiO2-OV catalyst with uniform Pd nanoparticles deposition demonstrates a remarkably thermocatalytic activity toward rapid, efficient reduction of nitroaromatics in water. The reaction proceeds efficiently using HCOONH4 as a hydrogen source under ambient conditions. The controlled experiments show that the (•)CO2(-) radicals produced by dehydrogenation of HCOONH4 are the main active species for the selective nitro reduction. Moreover, defective TiO2 nanostructures deposited with Pd nanoparticles, featuring excellent visible-light absorption via the creation of oxygen vacancies, can take advantage of the solar and thermal energy to drive catalytic reduction reactions more efficiently at room temperature. During this process, the oxygen vacancies and Pd nanoparticles play synergetic roles in the photoreduction of nitro compounds. Our work would be beneficial for implementation of a novel defect-mediated catalytic system in which solar light energy can be coupled with thermal energy to drive an energy efficient catalytic process.

Chemoselective Reductions of Nitroaromatics in Water at Room Temperature

A robust and green protocol for the reduction of functionalized nitroarenes to the corresponding primary amines has been developed. It relies on inexpensive zinc dust in water containing nanomicelles derived from the commercially available designer surfactant TPGS-750-M. This mild process takes place at room temperature and tolerates a wide range of functionalities. Highly selective reductions can also be achieved in the presence of common protecting groups.

Limiting Activity Coefficients of Some Aromatic and Aliphatic Nitro Compounds in Water

Limiting activity coefficients of nine nitroaromatic compounds and four nitroalkanes in water were determined in the range of environmentally related temperatures by measuring suitable phase equilibria. For liquid and solid nitroaromatics (nitrobenzene, 2-nitrotoluene, 3-nitrotoluene, 4-nitrotoluene, 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 1-chloro-2-nitrobenzene, and 1-chloro-4-nitrobenzene) the aqueous solubilities were measured by a conventional batch contacting method with UV spectrophotometric analysis, while for nitroalkanes (nitromethane, nitroethane, 1-nitropropane, and 2-nitropropane) the air-water partitioning (Henry`s law constant H{sub 12} or air-water partition coefficient K{sub aw}) was determined by the inert gas stripping method employing gas chromatography. Whenever possible, results were compared to literature values. Calculation of H{sub 12} or K{sub aw} for nitroaromatics from the measured solubilities is hindered by the lack of reliable vapor pressure data. On the basis of the temperature dependences of the solubilities measured, the enthalpies of solution at infinite dilution for the nitroaromatics in water were evaluated.

Uptake of weakly hydrophobic nitroaromatics from water by semipermeable membrane devices (SPMDs) and by goldfish ( Carassius auratus)

Semipermeable membrane devices (SPMDs) filled with triolein, and goldfish ( Carassius auratus) were simultaneously exposed to nine weakly hydrophobic nitroaromatics in a laboratory continuous-flow experiment. The results showed that the device concentrated the compounds in most cases to a larger extent than fish and that the overall uptake rate constants ( K μ ) and average pollutant sampling rates ( R s ) were similar. We conclude that the SPMDs may be used to determine the levels of weakly hydrophobic nitroaromatics in water. It is obvious, however, that more researches at laboratory in order to establish kinetic database for a wide spectrum of compounds varying in lipophilicity and other properties are needed to elucidate various theoretical and practical aspects of the use of membranes in the environmental research and for related practical applications.

Liquid chromatographic determination of nitroaromatics in water following solid phase extraction, pre-column reduction and derivatization

A selective and sensitive method for determination of nitroaromatics is described. The analytes were reduced to corresponding primary amines with iron powder and then derivatized with fluram in citrate buffer to form pyrrolinones. The highly fluorescent pyrrolinones were isolated and preconcentrated by octadecylsilane solid phase extraction cartridge followed by reversed-phase, high-performance liquid chromatographic analysis. Detection was at 395–495 nm. Various aspects such as the reduction process, derivatization, solid phase extraction and chromatographic separation were optimized. Analysis time was relatively short due to a special design for successive reduction and preconcentration. Limits of detection for 3-nitrophenol, nitrobenzene, 4 and 2-nitrotoluene were less than 60, 12, 60 and 280 ng L−1 respectively.