Broad pH Range Research Articles

PH-dependent mechanisms of sulfadiazine degradation by natural pyrite-driven heterogeneous Fenton-like reactions

The development of a natural pyrite/peroxymonosulfate (PMS) system for the removal of antibiotic contamination from water represented an economic and green sustainable strategy. Yet, a noteworthy knowledge gap remained considering the underlying reaction mechanism of the system, particularly in relation to its pH sensitivity. Herein, this paper investigated the impacts of critical reaction parameters and initial pH levels on the degradation of sulfadiazine (SDZ, 3 mg/L) in the pyrite/PMS system, and elucidated the pH dependence of the reaction mechanism. Results showed that under optimal conditions, SDZ could be completely degraded within 5 min at a broad pH range of 3.0–9.0, with a pseudo-first-order reaction rate of >1.0 min−1. The low or high PMS doses could lower degradation rates of SDZ through the decreased levels of active species, while the amount of pyrite was positively correlated with the removal rate of SDZ. The diminutive concentrations of anions exerted minor impacts on the decomposition of SDZ within the pyrite PMS system. Mechanistic results demonstrated that the augmentation of pH levels facilitated the transition from the non-radical to the radical pathway within the natural pyrite/PMS system, while concurrently amplifying the role of •OH in the degradation process of SDZ. This could be attributed to the change in interface electrostatic repulsion induced by pH fluctuations, as well as the mutual transformation between active species. The stable presence of the relative content of Fe(II) in the used pyrite was ensured owing to the reduced sulfur species acting as electron donors, providing the pyrite/PMS system excellent reusability. This paper sheds light on the mechanism regulation of efficient removal of organic pollutants through pyrite PMS systems, contributing to practical application.

Preparation of a low-temperature demulsifier derived from natural cottonseed oil

In this study, a low-temperature demulsifier (TEP-L) was synthesized by a simple method using polyethylene glycol 1000, and low-cost and readily accessible cottonseed oil as raw materials. The cottonseed oil was first hydrolyzed and then directly reacted with polyethylene glycol 1000 to obtain TEP-L. The chemical composition of TEP-L was determined by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance hydrogen spectroscopy (1H NMR). A comprehensive investigation was conducted to explore the demulsification performance of TEP-L in water-in-oil (W/O) emulsion. The investigation notably considered the effect of demulsifier dosage, temperature, settling time, pH value, and salinity on the demulsification process. The results demonstrated that the dehydration rate (DR) could reach 100 % with 1000 mg/L of TEP-L at 40 ℃ for 21 h, or a dosage of 500 mg/L at 60 ℃ for 240 min. Moreover, TEP-L exhibited a DR exceeding 90 % over a broad pH range of 8–12 and displayed remarkable resistance to salt. Characterization methods such as surface tension (SFT), dynamic interface tension (IFT), zeta potential, and optical microscopy observation were utilized to investigate the demulsification mechanisms.

Unraveling the outstanding catalytic efficiency of unprocessed bone-derived biochar: A deep dive into the mechanisms of native organic encapsulation and defective nitrogen doping in boosting persulfate activation for tetracycline degradation

Designing efficient non-metallic catalysts for persulfate (PS) activation has attracted broad attention due to their demonstrated immense potential in environmental remediation. In this study, unprocessed pig bone waste was successfully converted into biochars (PBCs) through a straightforward one-step pyrolysis process, which function as efficient PS catalysts for the removal of tetracycline (TC). The results revealed that the endogenous inner layer hydroxyapatite activator (IHA) and the rich native outer layer organic component wrapped with nitrogen-doped additives (OONA) found in raw bone-derived waste biomass collaborate to exert a dual effect of template and surface modification at 900 °C. Notably, under this synergistic action, 900PBC exhibited active defect nitrogen (pyridinic and graphitic nitrogen), sp2-hybridized groups (C = C, C = O, and C = N) and high defect levels (ID/IG = 1.0291), along with a cross-linked micro-mesoporous structure. This unique combination of properties endowed 900PBC with excellent catalytic activity, enabling it to effectively remove 50 mg/L of TC in the PS system within 30 min, primarily through a dual reaction pathway involving oxygen-active species (O2·-, 1O2) and electron transfer (fitting instantaneous-current values to PS concentrations, R2 = 0.95). Density-functional theory calculations confirmed that, within the nitrogen configurations located at defect sites, pyridinic nitrogen exerted a significant influence on the electron cloud density of adjacent carbon networks, subsequently promoting the formation of excited states of PS. Meanwhile, graphitic nitrogen constructed electron bridges with adjacent sp2-hybridized orbitals, facilitating the formation of the metastable complex 900PBC-PS*. Remarkably, 900PBC also exhibited excellent cyclic stability, maintaining a 93 % TC removal rate after four cycles,as well as high tolerance to a broad pH range (3–9), high concentrations of coexisting ions (10 mM), and diverse real-world water bodies. This study offers novel insights into synthesizing high-value biochar from waste bones with high catalytic activity.

Imidacloprid removal by modified graphitic biochar with Fe/Zn bimetallic oxides

Coping with the critical challenge of imidacloprid (IMI) contamination in sewage treatment and farmland drainage purification, this study presents a pioneering development of an advanced modified graphitic white melon seed shells biochar (Fe/Zn@WBC). The Fe/Zn@WBC demonstrates a substantial enhancement in adsorption efficiency for IMI, achieving a remarkable removal rate of 87.69% within 30 min and a significantly higher initial adsorption rate parameter h = 4.176 mg g−1·min−1. This significant improvement outperforms WBC (12.22%, h = 0.115 mg g−1·min−1) and highlights the influence of optimized adsorption conditions at 900 °C and the graphitization degree resulting from Fe/Zn bimetallic oxide modification. Characterization analysis and batch sorption experiments including kinetics, isotherms, thermodynamics and pH factors illustrate that chemical adsorption is the main type of adsorption mechanism responsible for this superior ability to remove IMI through pore filling, hydrogen bonding, hydrophobic interaction, electrostatics interaction, π-π interactions as well as complexation processes. Furthermore, we demonstrate exceptional stability of Fe/Zn@WBC across a broad pH range (pH = 3–11), co-existing ions presence along with humic acid under various real water conditions while maintaining high removal efficiency. This study presents an advanced biochar adsorbent, Fe/Zn@WBC, with efficient adsorption capacity and easy preparation. Through three regeneration cycles via pyrolysis method, it demonstrates excellent pyrolysis regeneration capabilities with an average removal efficiency of 92.02%. The magnetic properties enable rapid separation facilitated by magnetic analysis. By elucidating the efficacy and mechanistic foundations of Fe/Zn@WBC, this research significantly contributes to the field of environmental remediation by providing a scalable solution for IMI removal and enhancing scientific understanding of bimetallic oxides-hydrophilic organic pollutant interactions.

Structural characterization of ligand binding and pH-specific enzymatic activity of mouse Acidic Mammalian Chitinase

Chitin is an abundant biopolymer and pathogen-associated molecular pattern that stimulates a host innate immune response. Mammals express chitin-binding and chitin-degrading proteins to remove chitin from the body. One of these proteins, Acidic Mammalian Chitinase (AMCase), is an enzyme known for its ability to function under acidic conditions in the stomach but is also active in tissues with more neutral pHs, such as the lung. Here, we used a combination of biochemical, structural, and computational modeling approaches to examine how the mouse homolog (mAMCase) can act in both acidic and neutral environments. We measured kinetic properties of mAMCase activity across a broad pH range, quantifying its unusual dual activity optima at pH 2 and 7. We also solved high-resolution crystal structures of mAMCase in complex with oligomeric GlcNAcn, the building block of chitin, where we identified extensive conformational ligand heterogeneity. Leveraging these data, we conducted molecular dynamics simulations that suggest how a key catalytic residue could be protonated via distinct mechanisms in each of the two environmental pH ranges. These results integrate structural, biochemical, and computational approaches to deliver a more complete understanding of the catalytic mechanism governing mAMCase activity at different pH. Engineering proteins with tunable pH optima may provide new opportunities to develop improved enzyme variants, including AMCase, for therapeutic purposes in chitin degradation.

Structural characterization of ligand binding and pH-specific enzymatic activity of mouse Acidic Mammalian Chitinase.

Chitin is an abundant biopolymer and pathogen-associated molecular pattern that stimulates a host innate immune response. Mammals express chitin-binding and chitin-degrading proteins to remove chitin from the body. One of these proteins, Acidic Mammalian Chitinase (AMCase), is an enzyme known for its ability to function under acidic conditions in the stomach but is also active in tissues with more neutral pHs, such as the lung. Here, we used a combination of biochemical, structural, and computational modeling approaches to examine how the mouse homolog (mAMCase) can act in both acidic and neutral environments. We measured kinetic properties of mAMCase activity across a broad pH range, quantifying its unusual dual activity optima at pH 2 and 7. We also solved high-resolution crystal structures of mAMCase in complex with oligomeric GlcNAcn, the building block of chitin, where we identified extensive conformational ligand heterogeneity. Leveraging these data, we conducted molecular dynamics simulations that suggest how a key catalytic residue could be protonated via distinct mechanisms in each of the two environmental pH ranges. These results integrate structural, biochemical, and computational approaches to deliver a more complete understanding of the catalytic mechanism governing mAMCase activity at different pH. Engineering proteins with tunable pH optima may provide new opportunities to develop improved enzyme variants, including AMCase, for therapeutic purposes in chitin degradation.

Enhancing Fenton-like degradation efficiency over a broad pH range through synergistic interactions among varied acidity sites in M1-O-M2 structures

This study introduced a novel catalyst, Cu-Fe@CTS (Chitosan)-ATP (attapulgite), which distinguished itself from traditional Fenton-like catalysts by effectively degrading pollutants across a broad pH range. This catalyst achieved impressive degradation rates of 200 mg L−1 of FA (Fulvic acid), reaching 97 % at pH = 3, 96 % at pH = 7, and 95 % at pH = 10. The catalyst’s enduring effectiveness, with FA removal rates marginal decrease to 94 % at pH = 3 after ten cycles, showcased its sustained catalytic activity. The underlying mechanism was attributed to a synergistic interaction facilitated by the addition of Cu2+ and Fe3+ into ATP’s framework, which generated a M1-O-M2 structure. Experimentation and analysis revealed a dynamic electron transfer mechanism within the M1-O-M2 structure. Moreover, the catalyst proved to be highly effective in treating real wastewater-leachate concentrate, underscoring its potential for environmental remediation across diverse pH conditions. This research laid the groundwork for expanding the pH applicability of catalysts, opening new pathways for advanced environmental clean-up strategies.

Biochemical characterization of an esterase from Thermobifida fusca YX with acetyl xylan esterase activity.

Esterases (EC 3.1.1.X) are enzymes that catalyze the hydrolysis ester bonds. These enzymes have large potential for diverse applications in fine industries, particularly in pharmaceuticals, cosmetics, and bioethanol production. In this study, a gene encoding an esterase from Thermobifida fusca YX (TfEst) was successfully cloned, and its product was overexpressed in Escherichia coli and purified using affinity chromatography. The TfEst kinetic assay revealed catalytic efficiencies of 0.58s-1mM-1, 1.09s-1mM-1, and 0.062s-1mM-1 against p-Nitrophenyl acetate, p-Nitrophenyl butyrate, and 1-naphthyl acetate substrates, respectively. Furthermore, TfEst also exhibited activity in a pH range from 6.0 to 10.0, with maximum activity at pH 8.0. The enzyme demonstrated a half-life of 20min at 70°C. Notably, TfEst displayed acetyl xylan esterase activity as evidenced by the acetylated xylan assay. The structural prediction of TfEst using AlphaFold indicated that has an α/β-hydrolase fold, which is consistent with other esterases. The enzyme stability over a broad pH range and its activity at elevated temperatures make it an appealing candidate for industrial processes. Overall, TfEst emerges as a promising enzymatic tool with significant implications for the advancement of biotechnology and biofuels industries.

Peroxymonosulfate activation by iron-cobalt bimetallic phosphide modified nickel foam for efficient dye degradation

Novel catalysts with multiple active sites and rapid separation are required to effectively activate peroxymonosulfate (PMS) for the removal of organic pollutants from water. Therefore, an integrated catalyst for PMS activation was developed by directly forming Co–Fe Prussian blue analogs on a three-dimensional porous nickel foam (NF), which were subsequently phosphorylated to obtain cobalt-iron bimetallic phosphide (FeCoP@NF). The FeCoP@NF/PMS system efficiently degraded dye wastewater within 20 min. The system exhibited excellent catalytic degradation over a broad pH range and at high dye concentrations due to the presence of unique asymmetrically charged Coa+ and Pb− dual active sites formed by cobalt phosphides within FeCoP@NF. These active sites significantly enhanced the catalytic activity of PMS. The activation mechanism of PMS involves phosphorylation that accelerates electron transfer from FeCoP@NF to PMS, to generate SO4·–, ·OH, O2·–, and 1O2 active species. Three-dimensional FeCoP@NF could be readily recycled and showed good stability for PMS activation. In this study, a highly efficient, stable, and readily recyclable integrated catalyst was developed. This catalyst system effectively resolves the separation and recovery issues associated with conventional powder catalysts and has a wide range of potential applications in wastewater treatment.

Analysis of a new phage, KZag1, infecting biofilm of Klebsiella pneumoniae: genome sequence and characterization

BackgroundThis study investigates the effectiveness of the bacteriophage KZag1 against drug-resistant Klebsiella pneumoniae, aiming to assess its potential as a therapeutic agent. The novelty lies in the characterization of KZag1, a Myovirus with specific efficacy against multidrug-resistant K. pneumoniae strains. This highlights the significance of exploring alternative strategies, particularly phage therapy, in addressing biofilm-associated infections.MethodsKZag1, characterized by a typical Myovirus structure with a 75 ± 5 nm diameter icosahedral head and a 15 ± 5 nm short tail, was evaluated in experimental trials against 15 strains of K. pneumoniae. The infection cycle duration was determined to be 50 min, resulting in an estimated burst size of approximately 83 plaque-forming units per colony-forming unit (PFU/CFU). Stability assessments were conducted within a pH range of 4 to 12 and temperatures ranging from 45°C to 60°C. Biofilm biomass reduction was observed, particularly at a multiplicity of infection (MOI) of 10.ResultsKZag1 demonstrated infection efficacy against 12 out of 15 tested K. pneumoniae strains. The phage exhibited stability across a broad pH range and at elevated temperatures. Notably, treatment with KZag1 significantly reduced K. pneumoniae biofilm biomass, emphasizing its potential in combating biofilm formation. Genomic analysis revealed a complete genome of 157,089 base pairs with a GC content of 46.38%, encompassing 203 open reading frames (ORFs) and a cysteine-specific tRNA sequence. Comparison with phage GP4 highlighted similarities, with KZag1 having a longer genome by approximately 4829 base pairs and a higher GC content by approximately 0.93%. Phylogenetic analysis classified KZag1 within the Myoviridae family.ConclusionThe efficacy of KZag1 against K. pneumoniae biofilm suggests its potential as a therapeutic candidate, especially for drug-resistant infections. Further clinical research is warranted to explore its synergy with other treatments, elucidate genomic traits, compare with Myoviridae phages, and understand its host interactions. These findings underscore the promising role of KZag1 in addressing drug-resistant bacterial infections.

Construction of a gelatin aerogel catalyst functionalized with LaCoO3 and g-C3N5 for efficient ciprofloxacin degradation via adsorption and peroxymonosulfate activation

Three-dimensional porous gelatin-based aerogels functionalized with LaCoO3 and nitrogen-rich graphitic carbon nitride (g-C3N5) were successfully fabricated via a freeze-drying approach. Herein, the gelatin-based aerogels served as excellent adsorbents and catalysts activating peroxymonosulfate (PMS) to efficiently degrade ciprofloxacin (CIP) from aqueous solutions. In comparison to the pristine gelatin aerogel (GA), the optimized functionalized aerogel (GA–LCCN-1.5) demonstrated a 17.0% superior CIP adsorption performance. Remarkably, GA–LCCN-1.5 exhibited 95.7% removal efficiency for CIP, attributed to the effective generation of •OH, SO4•−, and 1O2 via PMS activation. In addition, high degradation efficiencies over 84.1% were maintained throughout a broad pH range of 3–9. Notably, GA–LCCN-1.5 demonstrated outstanding stability and reusability, with 93.2% CIP removal efficiency even after five reuse cycles indicating significant promise in real applications. Radical quenching and electron spin resonance (ESR) analysis suggest that CIP degradation was dominated by radical and non-radical routes through GA–LCCN-1.5 catalyzed PMS decomposition. Besides, the plausible CIP degradation mechanisms were systemically analyzed and proposed. The toxicities of CIP and the intermediate by-products were evaluated and reported. The findings of this study and insights demonstrate a facile construction of a biopolymer-based aerogel catalyst for synergistic and efficient PMS activation for the removal of antibiotics in water.

Cu quantum dots anchored core-shell submicrosphere catalyst for electro-enhanced degradation of diclofenac sodium

The low mass transfer efficiency, sluggish redox cycles of metal ions, and poor recycling rate of S2O82-→SO42-→S2O82- greatly limit the application of two-dimensional (2D) electrodes and persulfate (PS) techniques. In this study, an interface engineering strategy was developed to anchor Cu quantum dots (CuQDs) onto a novel Cu-CoO@NC (N-doped carbon) core-shell submicrosphere catalyst. The 3D electrochemical system (2D electrodes combined with Cu-CoO@NC particle electrodes) exhibited excellent catalytic behavior with 99.1 % removal of diclofenac sodium in 30 min. The Cu-CoO@NC catalyst presented effectiveness and strong environmental adaptability in a broad pH range, in actual water bodies, and for multiple PPCPs. Based on the results analyses of experiments and density functional theory (DFT) calculations, the excellent performances of Cu-CoO@NC/PS during electrochemical oxidation (EO) result from the effective mass transfer, efficient interfacial charge transport, rapid redox cycling of bimetallic ions promoted by cathode, repetitive cycle of S2O82- → SO42- → S2O82- caused by anode and multiple active sites of PS.

Oxygen-deficient AgIO3 for efficiently photodegrading organic contaminants under natural sunlight

Defect engineering is regarded as an effective strategy to boost the photo-activity of photocatalysts for organic contaminants removal. In this work, abundant surface oxygen vacancies (Ov) are created on AgIO3 microsheets (AgIO3-OV) by a facile and controllable hydrogen chemical reduction approach. The introduction of surface Ov on AgIO3 broadens the photo-absorption region from ultraviolet to visible light, accelerates the photoinduced charges separation and migration, and also activates the formation of superoxide radicals (•O2−). The AgIO3-OV possesses an outstanding degradation rate constant of 0.035 min−1, for photocatalytic degrading methyl orange (MO) under illumination of natural sunlight with a light intensity is 50 mW/cm2, which is 7 and 3.5 times that of the pristine AgIO3 and C–AgIO3 (AgIO3 is calcined in air without generating Ov). In addition, the AgIO3-OV also exhibit considerable photoactivity for degrading other diverse organic contaminants, including azo dye (rhodamine B (RhB)), antibiotics (sulflsoxazole (SOX), norfloxacin (NOR), chlortetracycline hydrochloride (CTC), tetracycline hydrochloride (TC) and ofloxacin (OFX)), and even the mixture of organic contaminants (MO-RhB and CTC-OFX). After natural sunlight illumination for 50 min, 41.4% of total organic carbon (TOC) for MO-RhB mixed solution can be decreased over AgIO3-OV. In a broad range of solution pH from 3 to 11 or diverse water bodies of MO solution, AgIO3-OV exhibits attractive activity for decomposing MO. The MO photo-degradation process and mechanism over AgIO3-OV under natural sunlight irradiation has been systemically investigated and proposed. The toxicities of MO and its degradation intermediates over AgIO3-OV are compared using Toxicity Estimation Software (T.E.S.T.). Moreover, the non-toxicity of both AgIO3-OV catalyst and treated antibiotic solution (CTC-OFX mixture) are confirmed by E. coli DH5a cultivation test, supporting the feasibility of AgIO3-OV catalyst to treat organic contaminants in real water under natural sunlight illumination.

Design and fabrication of magnetic cross-linked laccase aggregate using superparamagnetic metal-organic frameworks for phenol removal

Phenolic pollutants represent a significant environmental concern due to their widespread presence in industrial effluents, agricultural runoff, and urban waste streams. Enzymatic bioremediation emerges as a promising approach for the efficient removal of phenolic pollutants from contaminated environments. Laccases exhibit remarkable catalytic capabilities in degrading phenolic compounds into less harmful or even inert products. In this study, magnetic cross-linked laccase aggregate was prepared using superparamagnetic metal-organic frameworks and then was applied for phenol removal. The obtained results showed that the magnetic cross-linked laccase aggregate retains its activity across a broad pH range. Interestingly, (NH4)2SO4 exhibited a positive influence on enzyme activity, resulting in a relative activity of 137.7 %. The findings suggest that an optimal concentration range of 0.4–0.8 % can achieve maximum enzyme activity while avoiding potential negative impacts associated with excessive cross-linking. Optimal pH and temperature conditions were identified for enhanced phenol removal efficiency as pH 4.5 and 45℃, respectively. The investigation revealed the remarkable reusability of the cross-linked enzyme over multiple cycles. Harnessing the power of enzymes for phenolic pollutant remediation holds immense promise for mitigating environmental pollution and safeguarding public health.

Degradation of atrazine by ionizing radiation coupled with persulfate oxidation: Mechanism, pathway and toxicity assessment

The ubiquitous existence of atrazine (ATZ) in aquatic environments has aroused intense concerns, regarding its potential harmful effects on human health and ecology safety. Ionizing radiation has now drawn increasing attention in wastewater treatment. However, its unsatisfactory mineralization performance has significantly hindered the practical applications. Herein, the gamma radiation combined with persulfate oxidation (gamma/PS) system has been innovatively engineered to facilitate the removal of ATZ. Results showed that ATZ (10 mg/L) can be completely removed by gamma radiation with 1.0 kGy dose, and the pseudo-first-order kinetic model provided an good fit for the degradation. Gamma radiation can effectively remove ATZ with initial concentrations ranging from 5–20 mg/L, over a broad pH range (3.2–10.5), with the co-existence of inorganic anions (including CO32-, NO3-, and SO42-) and humic acid, and in actual waters (tap water and surface water). Degradation pathways of ATZ were proposed according to density functional theory (DFT) calculation and LC-MS analysis, including alkylic-hydroxylation, alkylic-oxidation, and dechlorination-hydroxylation. Moreover, gamma radiation was promising to reduce the toxicity of ATZ. Compared with the gamma radiation alone process, the gamma/PS system exhibited satisfactory ATZ removal performance. The k value rose by 4.78 times when PS (1 mM) was added, and TOC removal efficiency increased from 6.48 % to 34.53 % when PS was 4 mM. •OH and SO4•- participated in ATZ degradation, with •OH dominating. These results demonstrated that gamma/PS is a potential approach to degrade ATZ.

La0.5Sr0.5Fe0.5Ti0.5O3 as a Bifunctional Catalyst for H2/O2 Fuel Cells: Towards Enhanced Stability and Electroactivity

To address the rising demand for H2 for fuel cells, hydrogen is produced through water splitting (electrochemically/photoelectrochemically).Although perovskite-structured materials show promise for the oxygen reduction reaction (ORR), their effectiveness in the oxygen evolution reaction (OER) poses a challenge. Consequently, there’s a growing demand for bifunctional catalysts exhibiting high electroactivity across a broad pH range. One potential candidate for exploration as a negative electrode in batteries and fuel cells is LaFeO3. With co-substitution of Sr and Ti, La0.5Sr0.5Fe0.5Ti0.5O3 (LSFT) is formed and explored as an air electrode. In this study, we systematically assess LSFT as a bifunctional catalyst across a broad pH spectrum of electrolytic solutions. LSFT displays increased current densities in both the OER and hydrogen evolution reaction (HER) domains, alongside improved stability, notably in neutral conditions. Our investigation incorporates Density Functional Theory (DFT) simulations to determine surface binding energies and construct a Pourbaix diagram. The results underscore the robustness of LSFT as a perovskite-based bifunctional catalyst, achieving a cycle stability exceeding 600 cycles and a chronopotentiometric stability of 1500 h with a stable potential of ∼2 V at the current density of 150 mA/cm2 in the neutral environment.

Copper (II) Ion Detection in Food and Water Harnessing Schiff Base-Enabled Electrochemical Sensor

A copper (II) ion-selective sensor was generated using a processed membrane that included 4-(2-(2,4-Dinitrophenylhydrazono) Methyl)Benzene-1,3-diol (L). The sensor’s efficacy was tested using a variety of plasticizers, comprising sodium tetraphenylborate (NaTPB), O-Nitrophenyloctyl ether (ONPOE), benzyl acetate (BA), dibutyl phthalate (DBP), and dibutyl sebacate (DBS). Membrane layers comprised of L:DBS:OA:PVC in a ratio of 5:55:10:30 (w/w,%) provided optimum sensing effectiveness. The detection system performed well in an average concentration that ranged from 5.3×10−8 to 1.0×10−1 mol L−1, with a Nernstian slope of 29.1±0.5 mV decade-1 for Cu(II) ions. The sensor’s minimal detection limit of 2.1×10−8 mol, broad pH range (3.1–8.2), quick reaction time (9 s), strong non-aqueous resistance (up to 25% v/v), and good retention time (2 months) demonstrates its value. Potentiometric selectivity coefficients revealed an exclusive exposure for Cu(II) ions under the influence of intervening ions, allowing for accurate identification of copper in a variety of materials such as food oils, tomato plant material, and river water. The proposed sensor is a promising means for accurately detecting Cu(II) ions in environmental and food specimens, with potential utilization in quality assurance and environmental surveillance.

Extraction, catalytic study and milk-clotting properties of proteases from Brassicaoleracea

Proteases were extracted and biochemically characterized from different Brassica oleracea varieties (B. oleracea var. palmifolia (black cabbage, BC), B. oleracea var. sabellica (curly kale, K), and B. oleracea var. botrytis (white cauliflower, WC)). Calf rennet (CR) and Cynara cardunculus crude extracts (CC) were used as reference samples. The catalytic study used two different substrates: the synthetic peptide Bz-Phe-Val-Arg-pNA (BPVA-pNA), which contains para-nitroaniline (pNA), and azocasein (AzC) as a macromolecular substrate. The effect of temperature and pH on the proteolytic activity were also evaluated. Brassica proteases were further proposed as milk coagulants, and their coagulating efficiencies were evaluated. Bovine casein was incubated with the plant extracts, and the relative breakdown products were observed through electrophoresis. BC, K, and WC contain proteases which hydrolyze the macromolecular substrate (AzC) and synthetic peptides with Arg in P-1 (BPVA-pNA). Therefore, among the three B. oleracea varieties and control extracts, K leaf extracts displayed greater catalytic efficiency against AzC. Brassica extracts showed a lesser milk clotting index but visible milk curd formation. More importantly, the protease activities of BC and K extracts exhibited great catalytic activity over a broad range of pH (3.6–9.0) and temperatures (40–70 °C) using AzC as a substrate. Current pH and thermal tolerance results indicate that B. oleracea var. palmifolia and B. oleracea var. sabellica proteases could have broad applications in food technology. Many plant resources, which could represent potential sources of efficient proteases, are still unexploited.

Xylella phage MATE 2: a novel bacteriophage with potent lytic activity against Xylella fastidiosa subsp. pauca.

Xylella fastidiosa (Xf) is a major phytosanitary threat to global agricultural production. The complexity and difficulty of controlling Xf underscore the pressing need for novel antibacterial agents, i.e., bacteriophages, which are natural predators of bacteria. In this study, a novel lytic bacteriophage of Xf subsp. pauca, namely Xylella phage MATE 2 (MATE 2), was isolated from sewage water in southern Italy. Biological characterization showed that MATE 2 possessed a broad-spectrum of antibacterial activity against various phytobacteria within the family Xanthomonadaceae, a rapid adsorption time (10 min), and high resistance to a broad range of pH (4-10) and temperatures (4-60°C). Most importantly, MATE 2 was able to suppress the growth of Xf subsp. pauca cells in liquid culture for 7 days, demonstrating its potential as an effective antibacterial agent against Xf. The genomic and electron microscopy analyses revealed that MATE 2 is a new species tentatively belonging to the genus Carpasinavirus within the class Caudoviricetes, with an isometric capsid head of 60 ± 5 nm along with a contractile tail of 120 ± 7.5 nm. Furthermore, the high-throughput sequencing and de novo assembly generated a single contig of 63,695 nucleotides in length; representing a complete genome composed of 95 Open Reading Frames. Bioinformatics analysis performed on MATE 2 genome revealed the absence of lysogenic mediated genes, and genes encoding virulence factors, antibiotic resistance, and toxins. This study adds a new phage to the very short list of Xf-infecting lytic phages, whose in-vitro antibacterial activity has been ascertained, while its efficacy on Xf-infected olive trees in the field has yet to be determined.

A self-cleaning photocatalytic membrane loaded with Bi2O2CO3/In(OH)3 S-scheme heterojunction composites for removing tetracycline from aqueous solutions

Bi2O2CO3/In(OH)3 (BON) photocatalysts were synthesized by a one-pot method and loaded onto polyvinylidene fluoride (PVDF) membranes to obtain a Bi2O2CO3/In(OH)3/PVDF (BON-M) catalytic membrane system. The catalytic membranes demonstrated complete degradation of tetracycline within 40 min under visible light. They demonstrated robust photocatalytic activity across a broad pH range (5–11) and in the presence of coexisting ions. The membranes demonstrated excellent self-cleaning performance. Following exposure to light, the irreversible contamination decreased from 27.1% to 4.7% and the membrane’s permeability was almost completely restored. Moreover, the charge transfer mechanism at the S-scheme heterojunction interface of BON was demonstrated by Density functional theory and in-situ X-ray Photoelectron Spectroscopy characterisation, and the active sites involved in tetracycline’s degradation were identified. Meanwhile, the mechanism of the “anemone effect” of BON-M was demonstrated in conjunction with Electron paramagnetic resonance, and the intrinsic Some factors enhancing the membranes’ photocatalytic activity are specified.