Molecular interference and ecological restructuring: The acute strikes of nitroaromatics on anammox granular sludge.

Influencing factors of EPR detection of hydroxyl radicals in the Fenton system: The complicated roles of pH, zero-valent iron, and typical ligands.

Enhancement of nitrobenzene degradation by co-pyrolysis biochars in sulfide-mediated aqueous environment:adsorption and reduction contribution.

Engineering immobilized microbes with surface-displayed cold-adapted nitroreductase: An efficient strategy for nitrobenzene degradation at low temperature.

Innovative sandwich electrode-assembled bioelectrochemical system for efficient organic pollutants removal in low-conductivity groundwater.

Biosynthesised reduced graphene oxide/CuO based nanocomposite using 'Cordia dichotoma' leaf extract for 'nitrobenzene' determination.

The structure of self-assembled monolayers (SAMs) greatly influences electrochemical interface behavior. This study systematically examines how positional isomers of aromatic diamines (ADMs) assemble on a glassy carbon (GC) electrode and how such ordering affects the attachment and performance of electrochemically reduced graphene oxide (ERGO). SAMs of ortho-, meta-, and para-phenylenediamine (o-PDA, m-PDA, and p-PDA) were fabricated on GC and characterized using atomic force microscopy (AFM) and Raman spectroscopy. Among them, GC/p-PDA exhibited the most compact and homogeneous interfacial structure. ERGO was subsequently immobilized through the free amine functionalities of the SAM, as confirmed by attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV). Strong covalent coupling and electrostatic interactions between the positively charged ERGO and terminal amines enabled stable attachment. Under optimized conditions, the modified GC/p-PDA/ERGO electrode demonstrated exceptional electrocatalytic activity toward nitrobenzene (NBz) reduction, achieving a high sensitivity of 1410 μA mM−1 cm−2 and a low detection limit of 0.040 μM. In addition, this sensor displayed outstanding anti-interference capability, stability, and recovery in a water sample. These results establish GC/p-PDA/ERGO sensor as a robust and efficient electrocatalytically active interface for nitroaromatic pollutants detection and sustainable environmental monitoring.

Abstract An optimized Iron spinel ferrite (Fe 3 O 4 ) synthesis for the highest catalytic activity by the ultrasonic-assisted reverse co-precipitation (US-RP) method was tested, substituting the divalent cation (Me 2+ ) source from Fe 2+ for Zn 2+ , Ni 2+ or Co 2+ . The respective ZnFe 2 O 4 , NiFe 2 O 4 or CoFe 2 O 4 spinel ferrite nanoparticles were successfully synthesized in this work. The use of this US-RP method employing the ion source MeCl 2 (Me 2+ = Zn 2+ , Ni 2+ or Co 2+ ) yields a magnetic biphasic monocrystalline composite MeFe 2 O 4 /α-Fe 2 O 3 nanomaterial with potential photocatalytic properties. The amount of ferrite in the biphasic composite differed for each ion source, being 25.6%, 34.2%, and 38.2% for the CoFe 2 O 4 < NiFe 2 O 4 < ZnFe 2 O 4 , respectively. With an inverse trend in the magnetic properties, CoFe 2 O 4 > NiFe 2 O 4 > ZnFe 2 O 4 , with a magnetic saturation ( M s ) of 42.5, 28.4, and 2.7 emu g −1 . These magnetic properties were attributed to the differences in the degree of inversion ( δ ) calculated from Raman spectroscopy and Rietveld refinements. As for the photocatalytic potential for nitrobenzene (NB) degradation, the half-life calculated under the tested conditions was in the range of 72 – 113 min, following a reaction mechanism that yields H2O, CO 2 and 4-nitrophenol (4-NPh) as an intermediate product (< 5.65%). Showing an optimal efficiency at a pH = 2 when using the sample containing CoFe 2 O 4 . Graphical Abstract

This work describes the use of a pyrene-modified N-heterocyclic carbene (NHC)-stabilized Au13 nanocluster (denoted as Au NC) as the visible light photocatalyst in the multielectron reduction of nitrobenzene (NB). The photoreduction of NB to N-phenylhydroxylamine (PHA) proceeds with unity selectivity and product yield after 3 h of irradiation. The photocatalytic reduction proceeds via a four-electron and four-proton process. NB is first reduced by the excited state of the Au NC (Au NC*) to yield the ion pair (Au NC+ and NB•-). Further excitation of Au NC within the ion pair and involvement of external protons result in the reduction of NB•- to nitrosobenzene (NSB). The diffusion-controlled electron transfer in the first step is the rate-determining step, with the combination of dynamic and static quenching in the second step expediting electron transfer from Au NC* to NB•-. The third and fourth electron transfer events that lead to the final product are much faster than the first. Density functional theory (DFT) simulations link the selective formation of PHA to its weak adsorption on Au NC, driven by hydrophobic interactions and electronic effects of the pyrene ligands of Au NC. The excited-state reduction potential of Au NC* is -1.69 V vs SCE (Saturated Calomel Electrode), comparable to those of commonly used CdS quantum dot-based photocatalysts. This NB photoreduction study has afforded valuable insights into the intricate mechanisms at NHC-stabilized gold nanoclusters in energy-demanding multielectron transfer photocatalytic reactions.

Study on the efficiency of co-composting of nitrobenzene-contaminated soil and cow manure enhanced by manganese dioxide modified biochar and synthetic microbial communities.

During the preparation of Fe nanoparticles (NPs) through aqueous reduction of Fe3+, it is discovered that the addition of sodium anthraquinone-2-sulfonate (AQS) results in the formation of ultrasmall Fe crystallites (down to 1.0nm), which is the hitherto reported smallest Fe crystallite size. This crystallite-shrinking effect of AQS is rather unique and subtle, as its various structural analogs, including sodium benzenesulfonate, methanesulfonate, and anthraquinone-2-carboxylate, conversely increase the crystallite size of Fe NPs from 9.0 to 16.6-32.4nm. The applied AQS/Fe molar ratio is crucial to the crystallite-shrinking effect, with 0.5% as a noticeable threshold and 1% as the optimal dosage, respectively. The AQS-induced ultrasmall crystallite size steers significant changes in a spectrum of key physicochemical properties of Fe NPs, including smaller particle size with narrower distribution, uniform morphology, suppressed electrochemical impedance, and lowered Tafel corrosion potential. More importantly, AQS modulation results in 18.6- and 4.7-fold increase in the reactivity and electron efficiency of Fe NPs toward nitrobenzene (NB), respectively. In addition, AQS advances the thorough conversion of NB by Fe NPs to the terminal reduction product aniline, thus minimizing the accumulation of intermediates. This study opens an avenue to fabricate Fe NPs of 1-nm crystallite with significantly promoted reactivity and selectivity.

ABSTRACT The on‐time detection of hazardous chemicals is very important in ecological environments. In this work, two new transition metal‐based coordination polymers were synthesized by solvothermal method, namely [Zn(2,5‐dpa)(phen)·H 2 O] n (CP‐1) and [Co(2,5‐dpa)(dmphen)] n (CP‐2) (2,5‐dpa = 2,5‐pyridinedicarboxylic acid, phen = 1,10‐phenanthroline, dmphen = 2,9‐dimethyl‐1,10‐phenanthroline). The structures of CP‐1 and CP‐2 were analyzed by single‐crystal x‐ray diffraction. The results show that CP‐1 and CP‐2 exhibit 1D chain structure despite the use of different auxiliary ligands. Luminescence sensing experiments showed that CP‐1 can serve as a highly sensitive sensor for the selective detection of nitrobenzene (NB), as well as nitroimidazole antibiotics metronidazole (MDZ) and ornidazole (ODZ). The detection limits were found to be as low as 1.16 × 10 −5 M for NB, 1.53 × 10 −5 M for MDZ, and 1.26 × 10 −5 M for ODZ, respectively. The possible sensing mechanisms were subsequently analyzed through in‐depth experimental and computational research.

High-energy materials (HEMs) commonly feature relatively weak C-NO2 bonds that facilitate rapid decomposition, making the nitro group a key explosophore. Multiple electronic states play a significant role in the decomposition of HEMs. Therefore, exploring both ground- and excited-state potential energy surfaces (PESs) describing the dissociation processes is essential for gaining mechanistic insights. The trans and cis isomers of 1-nitropropene (NP) can be considered as minimal models for studying the photochemistry of nitro compounds such as nitrobenzene (NB) and ortho-nitrotoluene (oNT), respectively. These two isomers correspond to two different regions of the NP PES and can interconvert through torsional motion around the C═C double bond. However, their photochemistry other than along the torsional mode needs to be considered separately, as they are representative analogues of NB and oNT, where this torsional motion is restricted by the aromatic ring. The photochemical pathways of trans- and cis-NP starting from the lowest bright state, have been investigated using the complete active space self-consistent field (CASSCF) method combined with second-order perturbative energy corrections (CASPT2). This involves the optimization of various stationary points and minimum energy crossing points on the PESs of relevant singlet and triplet electronic states. Our results suggest that both the trans and cis isomers have similar photodecay channels, except that in the case of cis-NP, an additional excited-state intramolecular hydrogen transfer (ESIHT) path competes with dissociation and reduces the yield of photofragments. A total of four distinct energy transfer channels have been identified from the S1 PES regions of both trans and cis isomers of NP: (1) adiabatic pathways leading to NO2 (2B2) formation, (2) intersystem crossing (ISC) to the lowest triplet state, (3) internal conversion (IC) to the ground-state reactant in trans-NP or to a hydrogen-transferred product in cis-NP, and (4) IC resulting in the formation of dissociated photoproducts. Among the four processes, ISC has been found to be dominant, suggesting a high triplet quantum yield. The molecule on the lowest energy triplet state favorably relaxes to the ground-state reactant via ISC. Alternatively, the molecule can form either the epoxide or the NO + CH3-CH-CHO on the triplet state. In the case of cis-NP, a competing hydrogen transfer process also exists as a deactivation route on the T1 surface. NP generated through IC or ISC retains excess internal energy, which drives further transformations on the ground state. This includes nitro-nitrite isomerization followed by the dissociation into NO and CH3-CH-CHO. Two different mechanisms are identified for the nitro-nitrite isomerization: one involves a roaming transition state characterized by the partially dissociated NO2 moiety, and the other proceeds through a conventional transition state. The proposed dominant pathways and the corresponding photoproducts qualitatively explain the experimental observations of the photochemistry of NB and oNT.

ABSTRACTMetal–organic frameworks (MOFs) integrating fluorescence sensing and photocatalytic functions remain challenging to construct due to competing structural requirements. Herein, we report the synthesis, spectral and crystallographic characterization of two novel group organic skeletons composed of 5‐(1H tetrazol‐5‐yl) isophthalic acid (H3L) ligand (formula [Zn2L(H2O)3]n⋅nNO3 (Zn2L‐MOF‐1) and [Pb2L(OH)(H2O)]n⋅nH2O (Pb2L‐MOF‐2). Single crystal X‐ray analysis shows that Zn2L‐MOF‐1 forms an infinite three‐dimensional network structure and a double interpenetrating pcu topology through two symmetrical metal centers and a tetrazolium of L3− ligand. Pb2L‐MOF‐2 further forms a three‐dimensional supramolecular structure through hydrogen bonding between L3− ligand and free water molecules. Zn2L‐MOF‐1 can be used as an efficient multifunctional fluorescent material for the high sensitivity detection of metal cations Pb2+, Hg2+ and nitrobenzene (NB). The minimum limit of detection (LOD) can reach 10−7 M−1. In addition, Pb2L‐MOF‐2 was used as a light‐driven catalyst for the photodegradation of tetracycline (TC) antibiotics, with a photodegradation rate of 90.16% within 140 min. The possible sensing and photocatalytic mechanism of MOFs is explained through the comprehensive analysis of experiment and molecular orbital theory. This work establishes photoactive 3D MOFs as dual‐purpose materials for environmental monitoring and remediation, with topology‐dependent property modulation offering new design paradigms.

In light of the escalating water pollution problem, there is an urgent need to construct novel sensing materials capable of swift and real-time detection of pollutants. Coordination polymers (CPs) are widely used in the field of fluorescence sensing due to their special and novel structural characteristics. Here, the ligands 5-[(4-pyridyl)methoxy]isophthalic acid (H2PLIA) and 4,4-bis(imidazolyl)biphenyl (BIBP) with high symmetry are employed as precursors to synthesize luminescent CPs [Sm(PLIA)1.5(H2O)2]n (CP1) and [Cd2(PLIA)2(BIBP)(H2O)2]n (CP2) under solvothermal conditions. CP1 and CP2 are characterized by single-crystal X-ray diffraction, powder X-ray diffraction (PXRD), infrared spectroscopy (FT-IR), thermogravimetric (TG) analysis, and fluorescence spectrophotometry. Notably, the two CPs have different structural characteristics. CP1 presents a three-dimensional network structure, while CP2 presents a two-dimensional structure. And they have ideal thermodynamic and chemical stability as well as strong fluorescence performance. Fluorescence sensing tests showed that CP1 and CP2 have superior fluorescence recognition ability for Fe3+, Cr2O72-, and NB (nitrobenzene) in aqueous solution, with fast response time, strong selectivity, and high sensitivity. The possible mechanism of fluorescence recognition is due to the competitive absorption between CP1 and CP2 sensors and Fe3+, Cr2O72-, and NB in a water environment. These results provide valuable information for the multifunctional real-time fluorescence sensing platform for the detection of environmental pollutants in water bodies.

A series of toxic nitro compounds were converted to aryl amine derivatives at room temperature in the presence of a hydrogen source such as sodium borohydride and in commercially available mineral water without the need for an organic solvent. A commercial catalyst containing Pd (PdAlO(OH) NPs) was used as the supporting material in the study. However, the amount of catalyst used was reduced by 40% compared to the amounts used previously due to the effect of mineral water. Thanks to the developed environmentally friendly and practical method, 8 different nitro arene compounds were converted to aryl amine derivatives with yields over 95%. The most powerful aspect of the developed method is that it is economical and industrial.

In this study, what we believe to be a novel approach is presented whereby D-shaped polarization-maintaining photonic crystal fiber (PM-PCF) surface-enhanced Raman scattering (SERS) sensors are incorporated with a Raman spectrometer to achieve high sensitivity for the detection of organic pollutants (2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and nitrobenzene (NB)). The PM-PCF SERS probe was fabricated by applying a gold nanolayer of 40 nm thickness to the surface of the D-shaped fiber end. The organic pollutant-induced SERS signals are measured, and the sensing performance of the proposed sensors is examined through experimental analysis. The optimized structure exhibited a five-fold enhancement in SERS signals for 2,3,7,8-TCDD and a four-fold enhancement for NB compared to the conventional reflection configuration. Different 2,3,7,8 TCDD and NB concentrations in solution were detected, with limits of detection (LOD) of 1.35 x 10−11 M and 7.96 x10−12 M, respectively. This sensor, which features a highly sensitive SERS-active gold surface, is expected to be useful for online analysis and environmental monitoring. In the second part of this study, zirconium nanoparticles (ZrO2 NPs) were used to further enhance Raman signals in conjunction with a D-shaped PM-PCF sensor coated with a gold nanolayer. The ZrO2 NPs intensify the electromagnetic (EM) field near the sensor's surface due to their unique optical and surface characteristics. The integration of the ZrO2 NPs shows considerable potential for improving the performance of the D-shaped PM-PCF sensor in detecting trace amounts of organic pollutants with high precision. The dual-substrate SERS probe enhancement factor (EF) and LOD for 2,3,7,8-TCDD were 3.4 × 106 and 8.2 × 10−12 M, respectively.

Nitroaromatic compound (NAC)-contaminated sediments pose threats to aquatic ecosystems. The challenges of low mass transfer in sediments and the recalcitrance of NACs to degradation limit the effectiveness of conventional bioremediation techniques. This study demonstrates the potential of alternating current (AC)-driven bioredox cycling to overcome these barriers by coupling in situ reduction-oxidation processes. We report the successful application of AC stimulation in achieving the mineralization of nitrobenzene (NB) while elucidating its role in modulating bioredox dynamics, electron transfer, and electromicrobiome function. Sine-wave AC stimulation achieved an 87.7% reduction of NB and 90.3% mineralization of its intermediates. The AC stimulation promoted robust biofilm formation, enhanced bidirectional electrocatalytic activity, and increased microbial biomass. It also enriched a diverse microbial consortium capable of reducing NB, oxidizing aromatic intermediates, and facilitating electron transfer, as indicated by the upregulation of key enzymatic genes through multiomics analyses. Carbon metabolites from catechol meta-cleavage further supported nitro-reduction and sustained microbial viability. Compared to DC processes, AC-driven bioredox cycling reduced energy consumption by 16.8% in the remediation of NB-contaminated sediments. This approach offers a sustainable, low-carbon solution for efficient in situ biomineralization of NACs in sediments.

Specific detection of 2,4,6-trinitrophenol (TNP) is of fundamental importance for homeland security and environmental safety. Turn-off fluorescence sensors for TNP based on small organic fluorophores are gaining increasing attention for their excellent sensitivity and low cost. In experiment, the turn-off signal is generally attributed to the hydrogen bond-assisted charge transfer mechanism, in which the intermolecular hydrogen bond facilitates the photoinduced electron transfer (PeT) between the sensor and analyte. However, detailed computational works are usually not present to support this mechanism. This study performs a thorough investigation on the turn-off mechanism of a pyrene-based probe (PTC) for TNP with the aid of density functional theory (DFT) and time-dependent DFT (TDDFT) methods, presenting a novel π-π stacking-assisted PeT mechanism rather than the original hydrogen bond-assisted PeT mechanism. The investigation reveals that the π-π stacking model plants a lower-lying PeT state under the local excitation (LE) state of the PTC. π-π stacking, on one hand, enlarges the LUMO-LUMO gap between TNP and PTC; on the other, it renders considerable orbital overlap between the two LUMOs, which facilitates facile electron transfer from PTC to TNP and leads to fluorescence quenching. Moreover, the selectivity of the sensor in the presence of interfering nitro-aromatic compounds (NACs) is studied by taking nitrobenzene (NB) as an example. A similar PeT state is planted under the LE state in this case. However, for the first time, we observe a crossover of the PeT state and the LE state induced by NB. After photoexcitation, the PTC-NB complex will partially relax to the LE minimum via the minimal energy conical intersection (MECI) and the fluorescence is recovered. The selectivity of the sensor is well explained. This work expands our understanding of the effects of hydrogen bond and π-π stacking on the PeT process and provides new insights for the design of pyrene-based TNP sensors.

Treating nitrobenzene (NB) wastewater via an enhanced iron‒manganese oxides electron transfer strategy: Methods and mechanisms.