Search Results (259)

p-nitrophenol (p-NP) is a pollutant with environmental persistence, bioaccumulation potential, and significant health risks, and is widely dispersed in wastewater, so efficient removal of p-NP is imperative. Among the various methods, the catalytic reduction of p-NP to p-aminophenol (p-AP) using sodium borohydride (NaBH₄) is a particularly promising one and, herein, catalysts play a crucial role. Among the various metals, Au shows unique catalytic activity for p-NP reduction. However, nanosized Au often exhibit limited activity and stability due to their high surface free energy. To address this challenge, we designed and synthesized Au-SnO_x hybrid nanoparticles confined within hollow mesoporous silica nanoreactors (Au-SnO_x@hm-SiO₂) via a soft-template-assisted co-adsorption strategy. The resulting bimetallic Au-SnO_x@hm-SiO₂ nanoreactor showed significantly enhanced catalytic activity toward the NaBH₄-mediated reduction of p-nitrophenol (p-NP) compared with its monometallic Au@hm-SiO₂ counterpart, owing to the synergistic effect between Au and SnO_x. Among various Au/Sn ratios, the catalyst with an Au/Sn molar ratio of 1:0.1 demonstrated the highest activity, achieving complete conversion of p-NP within 5 min at a p-NP/Au molar ratio of 529:1—a tenfold improvement over Au@hm-SiO₂. Moreover, the catalyst maintained high efficiency over six consecutive cycles, with only slight deactivation, benefiting from the protective silica shell. Full article

The catalytic reduction of toxic 4-Nitrophenol (4-NP) to valuable 4-aminophenol is highly important for environmental remediation. However, developing catalysts with high activity, good recyclability, and facile preparation remains challenging. Herein, Ag@Fe₃O₄ nanocomposites were controllably synthesized with a facile one-pot polyol method. By varying the Ag:Fe precursor ratio, the structure could be tuned from dense and porous core-shell to Janus architectures. The porous Ag@Fe₃O₄ nanoreactors (Ag:Fe-0.4) exhibited exceptional catalytic performance, achieving complete 4-NP reduction within 75 s, with an apparent rate constant (k) of 6.29 × 10⁻² s⁻¹, a normalized rate constant (k_n) of 3742 s⁻¹ mmol⁻¹, and a TOF value of 1042 h⁻¹. XPS results verified that the excellent activity originated from the porous structure and interfacial charge transfer from Ag to Fe₃O₄. The catalysts showed super-paramagnetism and could be reused for at least eight cycles with >95% conversion retained. It also displayed high efficiency in reducing diverse nitroaromatics and in natural water. This work highlights the significance of structural and electronic modulation, providing a scalable strategy for magnetically recyclable catalysts toward environmental remediation and heterogeneous catalysis. Full article

Pesticide manufacturing industry wastewater is a complex mixture of potentially harmful components. If not properly treated, discharged effluents may pose serious risks to environment and organisms. In this study, influent and effluent wastewater samples from a pesticide factory were comprehensively non-screened by liquid chromatography high-resolution mass spectrometry, coupled with zebrafish embryo toxicity testing to assess whole effluent toxicity. A total of eight chemical groups were identified, including pesticides, antibiotics, nitrogen compounds, ketones, esters, amines and derivatives, other drugs, and other organic compounds. While wastewater treatment processes reduced most of the analyzed groups of compounds, compounds (e.g., 2-aminophenol, N-Nitrosodipropylamine, and carbamazepine) increased during the treatments. The influent samples were more toxic to zebrafish than the effluent samples in terms of lethality, teratogenic effects, developmental impacts, locomotor behavior, and neurotoxicity. The results showed that locomotor behavior was the most sensitive phenotypic toxicity endpoint, with significantly higher sensitivity than traditional acute lethal or teratogenic endpoints. Through a multi-dimensional assessment approach combining chemical screening, literature-based, risk ranking, and targeted quantification, we identified three predominant pesticide residues in the wastewater samples (both influents and effluents): hexaconazole, fenobucarb and isoprocarb. All three compounds exhibited additive or synergistic toxicity in zebrafish embryos. Exposure to ≥0.08% influent or ≥2% effluent increased inflammation (interleukin-1 beta, IL-1β), oxidative stress (copper/zinc superoxide dismutase, Cu/Zn-Sod), apoptosis (tumor protein p53, p53), and significantly impaired neurodevelopment in zebrafish larvae by altering the expression of sonic hedgehog a (shha), synapsin IIa (syn2a), and glial fibrillary acidic protein (gfap). This study suggests the necessity of incorporating non-apical endpoint (locomotor behavior) into whole effluent toxicity test, as this approach is essential for reducing the environmental risks posed by pesticide factory wastewater. Full article

Laccase plays an important role in the detection and degradation of phenolic compounds, but it is limited by its cost and stability. In this study, the laccase-like property of copper peptide (GHK-Cu) has been revealed. In terms of enzymatic reaction kinetics, GHK-Cu has a V_max of 1.735 × 10⁻⁴ mM·s⁻¹ and a K_m of 0.061 mM, demonstrating good substrate affinity and excellent catalytic efficiency. Then, a colorimetry was developed for rapid detection of epinephrine (EP) and 2-aminophenol (2-AP). The linear response range of EP is 20–240 μM, with a limit of detection (LOD) of 9.5 μM. The linear response ranges of 2-AP are 14–100 μM (in ultrapure water) and 2–120 μM (in seawater), with LODs of 2.56 μM and 1.65 μM. In addition, combined with a smartphone platform, a cotton-based sensor has been developed for the detection of 2-AP in seawater. The linear response ranges are 0–0.2 mM and 0.2–1 mM, with LOD of 0.033 mM. The structure of GHK-Cu provides a reference for the development of novel laccase mimetic enzymes. The constructed colorimetry offers an option for the rapid detection of phenolic compounds, and the developed cotton-based sensor enabled rapid and portable detection of 2-AP. Full article

In this paper, the target compound, 4-hydroxy-3-[[(2-hydroxy-1-naphthalenyl)methylene]amino]benzenesulfonamide (hereafter referred to as HA), was synthesized via the reaction of 2-hydroxy-1-naphthaldehyde with 2-aminophenol-4-sulfonamide in an 86% yield. In methanol–water (v/v, 1:1, pH 5.0 acetate buffer), HA displays a “turn-on” fluorescence response at 531 nm (λex = 411 nm) toward Al³⁺ with high selectivity over 17 common metal ions and 11 anions. The fluorescence intensity is linearly correlated to an Al³⁺ concentration from 1 to 10 µM (R² = 0.999) with a detection limit of 58 nM (3σ/k). Job’s plot and DFT calculations (M06/6-31G) both support a 1:1 binding stoichiometry. Under the tested conditions (with the methanol–water medium having an effective ionic strength equivalent to a low-salinity environment), the probe’s performance was unaffected. In natural aqueous samples (tap water and bottled water), which typically have low salinity (estimated as 0–5‰), Al³⁺ in the samples can also be chelated by the HA probe with a precision of relative standard deviation of less than 1%, and the recovery rate is higher than 90%. The probe exhibited acceptable relative recovery and low standard deviation, demonstrating a rapid and convenient novel method for detecting Al³⁺ in a natural aqueous sample. Full article

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. Full article

This study investigates orange peel valorisation through KOH pre-treatment and high-temperature pyrolysis (800 °C) to develop a highly porous activated char for the efficient removal of phenolic compounds, specifically 2,4-dinitrophenol (DNP) and aminophenol (AP), from water. The main objective of the study is to synthesise high-surface area activated char from orange peel and investigate its performance for the adsorption of DNP and AP from water. The synthesised adsorbent exhibited a Brunauer–Emmett–Teller (BET) specific surface area of 965 m²/g, contributing to its excellent phenol adsorption efficiency. Batch adsorption experiments were performed, and a maximum removal efficiency of 99% and 92% was observed at pH 4 and 7 with initial concentration 50 mg/L, contact time 60 min, and adsorbent dosage 0.6 g/L, for DNP and AP, respectively. The adsorption process was described by the Langmuir isotherm model (R² = 0.99), indicating monolayer adsorption and followed pseudo-second-order kinetics, achieving a maximum adsorption capacity of 366 mg/g for DNP and 341 mg/g for AP. Furthermore, DFT analysis revealed that DNP possesses a lower HOMO-LUMO energy gap (−0.54 eV), favouring a stronger adsorption interaction, whereas AP exhibited a relatively higher energy gap (−0.27 eV), corresponding to its comparatively lower adsorption capacity. Overall, the findings demonstrates that a single step chemical-thermal conversion of orange peel into biochar-based adsorbent offers a sustainable pathway for the removal of phenolic compounds from water. Full article

Proanthocyanidins (PACs) are a key group of bioactive phytochemicals known to provide health benefits. Most PACs are non-bioavailable polymeric molecules that need to be biotransformed by colonic microbes into simple metabolites to exert their pharmacological effects. In this study, six previously unexamined PAC metabolites from Saccharomyces cerevisiae, 3-aminophenol (3-AMP), 3-aminosalicylic acid, 2,4-dihydroxy-6-methylbenzaldehyde, 4-hydroxyphenylacetamide (4-HPA), 3-phenyllactic acid, and 2,4,6-trihydroxyacetophenone, were tested for their antiadipogenic activity using an insulin-dependent 3T3-L1 preadipocyte differentiation model. Lipid accumulation in differentiating preadipocytes was visualized and measured with the Oil Red O assay. Only 3-AMP and 4-HPA significantly reduced lipid accumulation at a concentration of 25 µM. To understand the cellular mechanisms, protein levels of key regulators of adipogenesis and lipid metabolism were analyzed using Western blotting. 3-AMP and 4-HPA may attenuate lipid accumulation by suppressing de novo lipogenesis, with 3-AMP downregulating the peroxisome proliferator-activated receptor (PPAR)-γ/acetyl-CoA carboxylase (ACC)/fatty acid synthase (FAS) axis and 4-HPA primarily inhibiting ACC/FAS signaling. Molecular docking studies indicated that 3-AMP may downregulate PPAR-γ expression through competitive inhibition of insulin receptors. These preliminary findings suggest that 3-AMP and 4-HPA exhibit potential antiadipogenic effects, highlighting PAC-derived postbiotics as promising nutraceuticals for mitigating obesity risk. Full article

This study developed a sonoseeding strategy for controlling the crystal size of acetaminophen during cooling crystallization by introducing sonication into a supersaturated solution, thereby inducing nucleation. Based on the synthetic route of acetaminophen, crystallization behavior in both water and acetic acid aqueous solutions was investigated, along with the influence of a structurally related additive, p-aminophenol, on nucleation. To establish the sonoseeding approach, the solubility of acetaminophen in water and an aqueous solution of acetic acid, with and without the additive, was measured over a temperature range of 10–70 °C using a titration method. In parallel, the nucleation temperatures and metastable zone widths of acetaminophen were systematically determined during cooling crystallization under varying operating conditions. Results demonstrate that sonication effectively induces nucleation and significantly narrows the metastable zone width, particularly in aqueous solutions of acetic acid. Guided by the determined solubility and nucleation behavior, sonoseeding crystallization experiments were conducted at various supersaturation levels, allowing for the efficient control of acetaminophen crystal size, which ranged from 27 μm to 95 μm, with narrower particle size distributions compared to spontaneous nucleation. Furthermore, the recrystallized acetaminophen was confirmed as Form I using PXRD, DSC, and FTIR analysis. This study demonstrates that the sonoseeding approach is an efficient method for controlling crystal size during the crystallization of active pharmaceutical ingredients. Full article

Redox mediators are central to electrochemical biosensors, enabling electron transfer between deeply buried enzymatic cofactors and electrode surfaces when direct electron transfer is kinetically inaccessible. Among all design parameters, the reversibility of mediator redox cycling remains the most decisive yet under-examined factor governing biosensor stability, drift and long-term reproducibility. This review establishes reversibility as a unifying framework grounded in inorganic and organometallic redox chemistry, with particular emphasis on coordination environments, ligand-field effects and outer-sphere electron-transfer pathways. Recent advances (2010–2025) in ruthenium and osmium polypyridyl complexes, cobalt macrocycles, hexacyanoferrates and Prussian Blue analogues are examined alongside ferrocene derivatives and other organometallic mediators, which together define the upper limits of reversible behaviour. Organic mediator families, including quinones, phenazines, indophenols, aminophenols and viologens, are discussed as mechanistic contrasts that highlight the structural and thermodynamic constraints that limit long-term cycling in aqueous media. Mechanistic indicators of reversibility, including peak separation, current ratios and heterogeneous electron-transfer rate constants, are linked to mediator architecture, coordination chemistry and immobilisation environment. By integrating molecular electrochemistry with applied sensor engineering, this review provides a mechanistically grounded basis for selecting or designing redox mediators that sustain efficient electron transfer, minimal fouling and calibration stability across diverse sensing platforms. Full article

This study describes a series of water-soluble half-sandwich ruthenium(II), rhodium(III), and iridium(III) complexes with α-diimine ligands containing substituted aromatic groups. These ligands were derived from glyoxal and 2-aminophenol (a), 4-methyl-2-aminophenol (b), 4-aminophenol (c), phenyl hydrazine (d), and 1-aminonaphthalene (e). The ruthenium(II) (1b–1e), rhodium(III) (2a–2c, 2e), and iridium(III) complexes (3a–3e) were obtained by reacting the ligands (a–e) with the corresponding dimeric precursor [(η⁶-p-cym)RuCl₂]₂ (p-cym = p-cymene) or [(η⁵-Cp*)MCl₂]₂ (Cp* = pentamethylcyclopentadienyl, M = Rh, Ir) in air and under nonanhydro conditions. The air-stable and water-soluble ruthenium(II), rhodium(III), and iridium(III) complexes were characterized via nuclear magnetic resonance spectroscopy and electrospray ionization–mass spectrometry. The structures of complexes [(η⁶-p-cym)Ru(d)Cl]Cl, 1d; [(η⁵-Cp*)Ir(a)Cl]Cl, 3a; and [(η⁵-Cp*)Ir(c)Cl]Cl, 3c were determined via single-crystal X-ray diffraction. Additionally, the complexes exhibited catalytic activity as precatalysts in formic acid decomposition. Complex [(η⁵-Cp*)Ir(d)Cl]Cl, 3d achieved turnover number (TON) and turnover frequency (TOF) values of up to 2150 and 3861 h⁻¹, respectively, at short reaction times. In the hydrogenation of carbon dioxide, [(η⁶-p-cym)Ru(e)Cl]Cl, 1e attained TON and TOF values of up to 1385 and 69.25 h⁻¹, respectively. Full article

The treatment of refractory nitrogenous organic matter in industrial wastewater management poses challenges in the removal of organic matter and nitrogen. To address these issues, this study utilized a novel composite hydrodynamic cavitator, mainly consisting of spiral pipes and a step drain, which could generate cavitation twice per pass at the throat of the spiral pipe and the step drain of the cavitation cavity, thereby distinguishing it from other existing cavitators that produce cavitation only once per pass. The composite hydrodynamic cavitator, optimized using ANSYS 19.2 simulation software, offers significant advantages in energy utilization and mass transfer efficiency. Moreover, it generates a high concentration of hydroxyl free radicals, which are crucial for organic matter degradation. Batch experiments demonstrated the effective treatment of 4-aminophenol. Within 120 min, 4-aminophenol degradation efficiency reached 74.7% and total nitrogen concentration decreased slightly from 1.28 mg/L to 1.06 mg/L, while ammonia nitrogen concentration initially increased before decreasing from its peak value of 0.82 mg/L to 0.77 mg/L. During the cavitation treatment of 4-aminophenol, intermediate products, such as benzoquinone, were generated. Under the strong oxidizing action of hydroxyl radicals, nitrogen undergoes deamination to form ammonium ions, which were likely removed predominantly as nitrogen gas. The experimental results are anticipated to establish a foundation for the application of hydrodynamic cavitation technology in the treatment of refractory organic wastewater degradation and to support denitrification processes. Full article

Skin sensitization is a critical endpoint in cosmetic safety assessment, necessitating reliable animal-free testing alternatives. Current established in chemico assays, such as the Direct Peptide Reactivity Assay and Amino acid Derivative Reactivity Assay, are limited by prolonged 24 h incubation periods and their inability to distinguish between direct electrophilic sensitizers and pro-electrophiles requiring metabolic activation or spontaneous oxidation. This study presents the design, synthesis, and validation of NNDNAC (N,N-dimethyl N-(2-(1-naphthyl)acetyl)-l-cysteine), a novel nucleophilic reactivity probe synthesized via a seven-step pathway. A modified naphthalene structure featuring N,N-dimethylamino substituent enhances nucleophilicity of the cysteine sulfur atom, enabling rapid reactivity assessment within an hour incubation using LC-DAD quantification. Comparative validation studies demonstrated that NNDNAC rapidly identified strong electrophilic sensitizers, achieving 100% and 98% depletion rates for p-benzoquinone and 2-methyl-4-isothiazolin-3-one, respectively, within 1 h. Critically, the NNDNAC assay successfully differentiated pro-electrophiles like p-phenylenediamine and 4-aminophenol, which showed negligible depletion at 1 h but significant depletion after 24 h due to auto-oxidation. Furthermore, NNDNAC classified farnesal as a weak sensitizer, aligning with established KeratinoSens™ and LLNA data. The NNDNAC probe represents a significant advancement in skin sensitization assessment, offering a time-efficient, high-throughput platform that not only accelerates screening processes but also provides crucial mechanistic insights through electrophile/pro-electrophile differentiation, significantly improving animal-free toxicological evaluations. Full article

Benzoxazoles are recognized as significant building blocks in organic synthesis and materials science. This work observed the formation of benzoxazole from o-aminophenol and o-hydroxybenzaldehyde using online ¹H NMR (continuous flow cell, 80 MHz). The identification of changes in the functional group was complemented by ATR-FTIR analysis. Additionally, the kinetic roles of phenylboronic acid and cyanide in the one-pot condensation-cyclization reaction are examined. Real-time monitoring has revealed three observable events: the rapid condensation of the aldehyde and o-aminophenol to produce the imine; the formation of the boron complex in the presence of phenylboronic acid; and the cyanide-assisted cyclization that converts the intermediate into benzoxazole. The findings clarify the transformations that control throughput and provide valuable insights for optimizing reagent loadings under environmentally friendly conditions. Full article