The heterogeneous reactions of nitrophenols and their impact on HONO generation: The influence of mineral dusts.

Industrial dyes and organic pollutants pose a significant water contamination and environmental challenges. Herein, manganese oxide nanoparticles (MnO2NPs) were biosynthesized using Equisetum diffusum extract as the reducing and stabilizing agents. The successful biosynthesis of MnO₂NPs was confirmed by a characteristic UV-Vis absorption peak at 416nm, a band gap of 2.4eV, and XRD analysis, which showed a tetragonal crystalline phase with an average crystallite size of 15nm. SEM and DLS analyses revealed spherical nanoparticles with average sizes of 55.73 ± 1.17nm and 66.2 ± 3.4nm, respectively, while a zeta potential of - 63.4 ± 5.8 mV indicated excellent colloidal stability. The biosynthesized MnO2NPs were investigated for their photocatalytic efficiency in the degradation of methylene blue (MB), methyl orange (MO), and para-nitrophenol (PNP) under sunlight irradiation. The biosynthesized MnO2NPs exhibited improved degradation efficiencies of 92 for MB, 93 for MO, and 90% for PNP in 100min under pH 7 conditions. At a dye concentration of 10mg/L, the degradation of MB, MO, and PNP was 92, 93, and 90%, respectively. Additionally, MnO2NPs dosage of 10mg/L, the degradation of MB, MO, and PNP reached 92, 93, and 91%, respectively. Moreover, recyclability studies demonstrated minimal loss of catalytic activity over five consecutive cycles, indicating the stability of the MnO2NPs. This eco-friendly synthesis of MnO2NPs offers a sustainable and cost-effective solution for wastewater treatment, highlighting their potential application in environmental remediation and pollutant degradation.

A comprehensive polyphasic taxonomic strategy was applied to the systematic characterization of strain DNPG3T, which was isolated from the river Ganges, Hooghly, West Bengal, India. The Gram-positive, halotolerant, heavy-metal-tolerant strain exhibited the ability to degrade p-nitrophenol (PNP). Cellular fatty acid analysis revealed that the predominant components were anteiso-C15:0 (24.61%), C11:0 (21.06%), iso-C16:0 (11.89%), C16:0 (11.58%), and anteiso-C17:0 (11.24%). Notably, the presence of C11:0, C10:0 2-OH as major fatty acids differentiate strain DNPG3T from its closely related members of the genus Brachybacterium. The predominant respiratory quinone was identified as menaquinone-7 (MK-7). Analysis of 16S rRNA gene sequence indicated that B. zhongshanense strain JBT was the closest relative of DNPG3T, sharing 97.08% sequence similarity. Genome-based ANI value calculated using the EzBioCloud server revealed that B. zhongshanense JCM 15471T was the closest genomic relative (85.49%). These values were further substantiated by digital DNA-DNA hybridization (dDDH) estimates calculated using the GGDC server. Taxonomic assignment using the GTDB database further indicated that strain DNPG3T constitutes a previously unrecognized species within the genus Brachybacterium. Genome analysis of strain DNPG3T identified eleven genomic islands, along with a rich repertoire of 194 carbohydrate-active enzyme (CAZyme) families, comprising 95 glycoside hydrolases and 53 glycosyltransferases. In addition, five biosynthetic gene clusters were detected. Collectively, these genomic features indicate the involvement of horizontal gene transfer events and highlighted the pronounced metabolic versatility of the strain, underscoring its potential for industrial enzyme production and secondary metabolite biosynthesis. Pan-genome analysis further indicates that the Brachybacterium pan-genome is open, reflecting substantial genetic diversity and ongoing gene acquisition within the genus. Comprehensive biochemical, physiological, chemotaxonomic, and phylogenetic analyses supported the assignment of strain DNPG3T to the genus Brachybacterium while clearly distinguishing it from all currently described species within the genus. Accordingly, strain DNPG3T was proposed to represent a novel species, for which the name Brachybacterium netajii sp. nov. is suggested. The type strain was DNPG3T (= MTCC13125T).

Silver-loaded granular activated carbon for fixed-bed drinking water treatment: antibacterial effect in both water and biofilm phases and impact on organic matter removal.

An activated sugarcane bagasse biochar (ASCBB) was used for constructing a filter module to remove p-nitrophenol (PNP) from contaminated water to introduce applicable tools for remediating pollutants. The PNP adsorption on the ASCBB filter was studied at different flow rates, pollutant dose levels, and ASCBB amounts. The PNP adsorption efficiency of ASCBB was evaluated and compared with its raw precursor, sugarcane bagasse (SCB). Furthermore, the reusability and regeneration potential of the ASCBB filter were investigated to ensure its long-term efficacy in removing PNP from aqueous solutions. A one-gram ASCBB filter achieved 94.98% removal of 50mg/L PNP at a flow rate of 2mL/min. Increasing the ASCBB adsorbent amount from 1 to 2g improved the removal of 500mg/L PNP from 75.96% to 92.84% at 2mL/min. Furthermore, the two-gram ASCBB filter can remove 85.60% of high tested concentration (1000mg/L) of PNP when pursuing a flow rate of 2ml/min. The results indicate that the ASCBB filter (2 gm) demonstrated good reusability by retaining 113mg out of 150mg of PNP after five separate cycles without regeneration. The ASCBB filter was restored completely after a simple regeneration process to be capable of retaining 68.2mg out of 90mg of PNP after three cycles without any further regeneration. This finding proved that the ASCBB filter can be used as a promising, sustainable, and reusable filter for removing the PNP from contaminated water.

The complete removal of persistent aromatic organic pollutants from aqueous environments demands the development of sustainable and highly efficient filtration materials. In this study, novel bio-sourced mixed-matrix membranes (MMMs) were successfully fabricated by incorporating the highly porous metal–organic framework MIL-68(Al) into a biodegradable polylactic acid (PLA) matrix via a solvent-induced phase inversion method. The integration of MIL-68(Al) nanoparticles significantly tailored the membrane’s morphological structure, endowing the hybrid membranes with enhanced surface hydrophilicity (water contact angle reduced from 90.3° to 72.7°) and superior permeability. The pure water flux reached an optimal value of 42.2 L m−2 h−1 at a 15 wt.% MOF loading. Crucially, the hybrid membranes exhibited exceptionally high adsorptive removal performance for p-nitrophenol (PNP) and methylene blue (MB). Driven by the abundant accessible active sites of the MOF filler, the MIL-20/PLA membrane achieved a maximum equilibrium adsorption capacity of 121.03 μg/cm2 (36.90 mg/g) for PNP, representing a remarkable 25.7-fold enhancement over the pristine PLA membrane. Kinetic analyses confirmed that the adsorption process is strictly governed by pseudo-second-order kinetics, indicating a chemisorption mechanism dominated by hydrogen bonding and π–π stacking interactions. Furthermore, the optimized membranes demonstrated outstanding dynamic filtration efficiencies (>80%) and robust regenerability over multiple continuous operating cycles. This work not only highlights the synergistic interfacial effects between MOFs and biodegradable polymers but also provides a highly effective, eco-friendly, and sustainable membrane platform for the advanced remediation of organic-contaminated wastewater.

A ratiometric fluorescence sensor for special detection of β-galactosidase and screening of its inhibitor in complex mixtures.

Bicarbonate enhances phenol degradation and nitro(so)phenol formation during nitrate photolysis: Importance of carbonate radical-mediated electron transfer process.

The rapid detection of organophosphorus (OP) compounds is crucial for safeguarding human health and ensuring food safety. This study presents a novel wearable electrochemical biosensor that integrates miniaturized screen-printed electrodes with wearable devices to achieve real-time, on-site OP detection. The biosensor was fabricated by constructing a screen-printed carbon electrode (SPCE) on a thermoplastic polyurethane (TPU) substrate, sequentially modified with graphene (GR), gold nanoparticles (AuNPs), and organophosphorus hydrolase (OPH), and finally encapsulated with Nafion. This SPCE/GR/AuNPs/OPH/Nafion configuration yields a highly flexible and portable device. The detection principle relies on the enzymatic hydrolysis of methyl paraoxon (MPOX) by OPH, generating p-nitrophenol (PNP), which is quantitatively measured via square wave voltammetry (SWV). The sensor exhibits a broad linear detection range (30-400 μM) with a strong linear correlation (R2 = 0.995) and a low detection limit (0.321 μM). It demonstrates excellent selectivity against common interfering substances, including urea, sucrose, and various metal ions. Application to real-world samples such as cabbage and tap water yielded high recoveries (107.2% for cabbage and 101.2% for tap water), with relative standard deviations (RSDs) below 8%. Furthermore, the biosensor maintains robust flexibility and mechanical resilience, with less than 5% signal loss after 100 bending cycles, confirming its suitability for wearable applications and reliable operation under mechanical stress. This innovative, flexible electrochemical biosensor provides a powerful and reliable platform for rapid OP detection, particularly in complex testing environments.

Directed evolution of APOX for proximity labeling using phenols with high redox potentials

Metabolic engineering of Halomonas cupida for co-mineralization of phenol and p-nitrophenol in high-saline wastewater.

Fe(III)-enhanced degradation of para-nitrophenol in a UV/monochloramine system: Mechanism and toxicity analysis.

ABSTRACT Rapid industrial development has led to wastewater discharge containing refractory toxic organics, posing a severe threat to aquatic ecosystems and water security. As a typical recalcitrant pollutant, p ‐nitrophenol (PNP) is hard to degrade due to its stable benzene ring and electron‐withdrawing nitro group, demanding efficient removal methods. This study synthesized a MIL‐53(Fe)/CuCo 2 S 4 composite (MCCS‐15, ‐20, ‐25, and ‐30) via hydrothermal method and constructed a heterogeneous photo‐Fenton system (composite/visible light/H 2 O 2 ) for PNP degradation. Among samples, MCCS‐25 exhibited the highest degradation performance, achieving a rate constant of 0.08613 min −1 , which is 9.06 and 23.03 times greater than that of MIL‐53(Fe) and CuCo 2 S 4 , respectively. Photoelectrochemical measurements revealed that the loading of CuCo 2 S 4 not only broadened the visible light absorption range of MIL‐53(Fe), but also significantly improved the separation efficiency of photogenerated electron‐hole pairs. Scavenger experiments and EPR analyses confirmed that hydroxyl radical (OH) and superoxide radical (O 2 − ) were the predominant reactive species in the degradation process. The possible degradation mechanism was proposed based on the band structures of MIL‐53(Fe) and CuCo 2 S 4 . The MIL‐53(Fe)/CuCo 2 S 4 /visible light/H 2 O 2 system demonstrates promising application potential for efficient degradation of PNP.

A green chemistry approach for the preparation of copper nanoparticles (CuNPs) using leaf extract of Hyptis capitata has been discussed. The presence of polyphenolic compounds and flavonoids in this plant was already confirmed and communicated by former researchers in their phytochemical studies. These biomolecules are efficient reducing and capping agents. After the successful synthesis, the CuNPs were characterized by UV-visible spectroscopy, FT-IR, XRD, HR-TEM, EDX, DLS, Zeta potential analyzer, and TGA techniques. The optical and morphological properties of CuNPs were elucidated using these characterization analyses. The average crystal size was found to be 12 nm. The characteristic SPR peak of CuNPs was obtained at 222.5 nm in the UV-visible absorption spectrum. CuNPs capped with HC leaf extract have the potential for catalytic transformation of pollutants methyl orange dye and 4-nitro phenol in aqueous system. Phytochemically stabilized CuNPs can inhibit the growth of gram-positive and gram-negative bacteria.

Nitrophenol (NP) and methylene blue (MB) are considered among the most hazardous organic contaminants frequently released from pharmaceutical, textile, and paper industries, posing significant risks to both human health and the environment. The conventional treatment involves adsorption, oxidation, biological, filtration, and other photochemical degradation methods, which often suffer from low efficiency, limited reusability, and the production of secondary toxic by-products. In this context, the nanomaterials (NMs) mediated catalytic reduction of MB into leucomethylene blue and p-NP into p-aminophenol (p-AP) has emerged as a promising approach, due to its high efficiency and effectiveness. This review emphasizes the green synthesis of NMs for catalytic applications, which align with the principles of the circular economy and the Sustainable Development Goals (SDGs). This thorough review systematically examines the mechanistic understanding of the reduction of both p-NP and MB via different green synthesized NMs and evaluating their catalytic efficiencies. Furthermore, a detailed discussion of the reduction of pollutants (p-NP and MB) is provided, along with their mechanistic insights. In addition, this paper also provides a comparative table highlighting the effects of using different precursors, experimental conditions on the conversion catalytic efficiency and reusability potency. Thus, this work provides the insights into recent research on the catalytic reduction of p-NP and MB into valuable products, highlighting the significance of green synthesized nanocatalysts for effective wastewater treatment.

Pseudomonas asiatica strain PNPG3 demonstrated broad-spectrum heavy-metal tolerance, with minimum inhibitory concentrations (MICs) of 800, 400, 4, and 6 µg/mL (ppm) for arsenite, cadmium (Cd), cobalt (Co), and nickel (Ni), respectively. When exposed to 1 mM arsenite, strain PNPG3 retained approximately 89% of its p-nitrophenol (PNP) degradation efficiency relative to the PNP-only baseline, mineralizing 86% of 0.5 mM PNP within 66 h and releasing 0.41 mM nitrite, indicating strong catabolic resilience under combined PNP–arsenite stress. Genome analysis identified a distinct arsenic (As) tolerance and biotransformation gene cluster on contig 1, comprising coordinated transport, regulatory, and metabolic components, including an ArsR/SmtB family transcriptional regulator and an ArsJ-associated glyceraldehyde-3-phosphate dehydrogenase, suggesting the presence of a specialized and potentially novel As detoxification mechanism. Comparative genomics further revealed conservation of key abiotic and biotic stress response genes, along with metabolic pathways supporting degradation of styrene, dioxins, polycyclic aromatic hydrocarbons, cyanate, and diverse aromatic xenobiotics. Chromate reductase (ChrR) and arsenate reductase (ArsC), key enzymes involved in the biotransformation of Cr (VI) to Cr (III) and arsenate [As(V)] to arsenite [As(III)], respectively, were modeled, characterized, and validated, followed by docking analyses to elucidate heavy-metal interactions at their active sites. Molecular dynamics simulation (MDS) indicated that the ArsC–arsenate complex exhibited higher structural stability and compactness, with limited conformational fluctuations, implied greater robustness of arsenate reduction compared to Cr(VI) reduction under in situ metal stress conditions. Overall, the phenotypic robustness and genomic potential of strain PNPG3 underscore its strong capacity for heavy-metal tolerance, PNP biodegradation, and arsenate biotransformation, highlighting its promise for scalable bioremediation applications.

The hydrogen-bond charge transfer complex (HB-CTC) formed between the donor, 1,10-phenanthroline (Phen), and the π-acceptor, p-nitrophenol (PNP), has been thoroughly investigated through theoretical studies. The molecular structure and the HOMO-LUMO energy gap (ΔEH-L) of this complex have been investigated by the density functional theory. This work has studied the HB-CTC complex through FTIR, 1HNMR, 13CNMR, and electronic absorption spectra. A molecular electrostatic potential surface (MESP) study allowed us to explore key aspects of intermolecular interaction. Moreover, reduced density gradient analysis was conducted to visualize valuable insights into non-covalent interactions within the complex components. Quantum Theory of Atoms in Molecules was used to analyze the interaction between the 1,10-phenanthroline and p-nitrophenol. The findings from this research not only enhance our understanding of HB-CT complexes but also highlight their exciting potential for innovative applications in various fields.

p-Nitrophenol (PNP), a highly toxic and recalcitrant organic pollutant prevalent in industrial wastewater, poses severe challenges to traditional Fenton treatment technologies. In this study, a novel nanoporous catalyst is synthesized via a combined annealing-dealloying strategy. Annealing at 550 °C and 600 °C induces partial crystallization, generating α-Fe and Fe2B phases that serve as preferential corrosion sites during chemical dealloying. This process results in a three-dimensionally interconnected nanoporous structure, which significantly increases the specific surface area of the catalyst to 2.642 m2/g. The optimized nanoporous catalyst exhibits excellent degradation performance, achieving complete removal of PNP within 30 min under room temperature reaction conditions. Notably, kinetic analysis reveals a degradation mechanism involving adsorption and Fenton-like catalysis. The high specific surface area provides abundant active sites for PNP adsorption, while the enhanced Fe2+ dissolution synergistically accelerates the degradation. The adsorption kinetic follows a pseudo-second-order model, and the degradation kinetic conforms to a first-order model, with activation energy analysis further confirming a surface-reaction-controlled process. This work provides a feasible approach and technical reference for designing efficient porous catalysts based on amorphous alloys for advanced treatment of refractory organic wastewater.

The development of efficient and stable electrochemiluminescence (ECL) emitters remains a major challenge in practical sensing applications. Although copper nanoclusters (CuNCs) have attracted increasing attention due to their low cost and molecule-like electronic structures, their ECL activity is often limited by disordered aggregation and weak radiative emission. In this study, we report a deprotonation-driven interfacial assembly strategy for CuNCs, leading to a remarkable enhancement in the ECL performance. Using 4,6-diamino-2-mercaptopyrimidine (DAMP) as a multifunctional reductant and capping ligand, disordered aggregates (CuNCsacid) formed under acidic conditions undergo structural evolution in response to pH, transforming into highly ordered nanosheets (CuNCsbase) in mildly alkaline media. This transformation is driven by the deprotonation of amino groups, which strengthens the interligand hydrogen bond networks and promotes π-π stacking, ultimately yielding compact structures enriched in Cu(I) species. The ordered assemblies effectively suppress nonradiative relaxation and lower the onset potential, leading to an ECL enhancement of nearly 3 orders of magnitude compared to that of CuNCsacid. Benefiting from these features, a highly sensitive ECL biosensor for N-acetyl-β-d-glucosaminidase (NAG) detection in human urine was constructed employing CuNCsbase as emitters. The signal is generated by the enzyme catalytic production of p-nitrophenol (PNP), which perturbs the hydrogen-bond-directed assembly of CuNCsbase, causing an activity-dependent decrease in the ECL signal. By establishing a pH-modulated assembly strategy to boost ECL emission, this study opens new avenues for the rational design of high-performance, CuNC-based bioanalytical luminophores.

The development of sensitive and efficient sensors for monitoring organic pollutants in water is of critical environmental importance. Transition metal oxides, particularly spinel Co3O4, present a promising platform, yet their performance hinges on their electronic structure. This study successfully synthesized Zn-, Fe-, Mn-, and Ni-doped spinel Co3O4 hollow nanocubes using a zeolitic imidazolate framework-8 (ZIF-8) template for the electrochemical detection of p-nitrophenol (PNP). Material characterization confirmed that doping effectively tuned the Co2+/Co3+ ratio and oxygen vacancy (OVs) concentration. Among the materials, Zn-Co3O4 exhibited the highest Co2+/Co3+ ratio and OVs content, which corresponded to its superior electrochemical performance for PNP detection, including high sensitivity (0.3461 μA μM-1) and low detection limit (5.24 nM). The enhanced performance is attributed to the elevated Co2+/Co3+ ratio boosting redox activity and the abundant OVs acting as prime adsorption sites for PNP molecules. The sensor also demonstrated excellent selectivity, stability, and applicability in real water samples. This work confirms that cation doping is an effective strategy for enhancing the sensing performance by regulating valence states and defect engineering.