Wide pH Range Research Articles

Poly(dimethyldiallylammonium chloride)-modified magnetic bentonite for removal of polystyrene nanoplastics

Nanoplastics (NPs) can contaminate water sources and living organisms, posing significant challenges for removal due to their small size and complex surface properties. There is a need to develop efficient technologies for the removal of NPs. In this study, bentonite was magnetically modified and loaded with Poly(dimethyldiallylammonium chloride) (PDMDAC) to enhance the adsorption for NPs, and improve separation and recovery efficiency. The synthesized PDMDAC-modified magnetic bentonite (PDMMB) had a high specific surface area of 49.386 m2/g and a maximum adsorption capacity of 250.50 mg/g for polystyrene nanoplastics (PS-NPs). The incorporation of PDMDAC increased the surface charge of magnetic bentonite from −39.50 mV to +37.7 mV, generating strong electrostatic attraction to the negatively charged PS-NPs (-64.3 mV). The PDMMB exhibited a saturation magnetization of 17.619 emu/g and an S-type hysteresis curve, indicating strong superparamagnetism that facilitating magnetic separation and recovery. Characterization analysis revealed that the adsorption was driven by electrostatic attraction and the Fe-O functional group. Kinetics and adsorption model analyses indicated that the adsorption mechanism involved electrostatic attraction, complexation, and single/multilayer adsorption, the adsorption process was exothermic and thermodynamically favorable. The adsorption rate remained at 86.41 % after 5 adsorption-desorption cycles. PDMMB exhibited high removal efficiency over a wide range of pH (3−10), ionic strength (0.01–0.5 mol/L), and in the presence of various anion types, indicating its potential for flexible application. The high efficiency, easy operation and excellent regeneration of PDMMB demonstrate its potential for effective removal of NPs from wastewater.

Great truths are always simple: A millimeter-sized macroscopic lanthanum-calcium dual crosslinked carboxymethyl chitosan aerogel bead as a promising adsorbent for scavenging oxytetracycline from wastewater

Given their increasing environmental and health harms, it is crucial to develop green and sustainable techniques for scavenging antibiotics represented by oxytetracycline (OTC) from wastewater. In the present work, a structurally simple lanthanum-calcium dual crosslinked carboxymethyl chitosan (CMCS-La3+-Ca2+) aerogel was innovatively synthesized for adsorptive removal of OTC. It was found that CMCS and La3+ sites collaboratively participated in OTC elimination, and OTC removal peaked over the wide pH range of 4–7. The process of OTC sorption was better described by the pseudo-second-order kinetic model and Redlich-Peterson model, and the saturated uptake amount toward OTC was up to 580.91 mg/g at 303 K, which was comparable to the bulk of previous records. The as-fabricated composite also exerted exceptional capture capacity toward OTC in consecutive adsorption-desorption runs and high-salinity wastewater. Amazingly, its packed column continuously ran for over 60 h with a dynamic uptake amount of 215.21 mg/g until the adsorption was saturated, illustrating its great potential in scale-up applications. Mechanism studies demonstrated that multifarious spatially-isolated reactive sites of CMCS-La3+-Ca2+ cooperatively involved in OTC capture via multi-mechanisms, such as n-π EDA interaction, H-bonding, La3+-complexation, and cation-π bonding. All the above superiorities endow it as a promising adsorbent for OTC-containing wastewater decontamination.

De Novo Design and Characterization of Amphiphilic Peptides with Basic Side Chains for Tailored Interfacial Chemistries.

Lysine-leucine (LK) peptides have been used as model systems and platforms for 2D material design for decades. LK peptides are amphiphilic sequences designed to bind and fold at hydrophobic surfaces through hydrophobic leucine side chains and hydrophilic lysine side chains extending into the aqueous subphase. The hydrophobic periodicity of the sequence dictates the secondary structure at the interface. This robust design makes them ideal candidates for controlling interfacial chemistry. This study presents the de novo design and characterization of two novel peptides: LRα14 and LHα14, which substitute lysine with arginine and histidine, respectively, in the helical LKα14 sequence. This modification is intended to expand the LK peptide platform to a new basic interfacial chemistry. We explore the stability of the new LRα14 and LHα14 designs with respect to changes in pH and salt concentration in bulk solution and at the interface using circular dichroism (UV-CD) and vibrational sum-frequency generation spectroscopy, respectively. Notably, the structural stability of the peptides remains unaffected across a wide range of pH and ionic strength values. At the same time, the variation of side-chain chemistry leads to a wide spectrum of interfacial water structures. By extension of the LK platform to include arginine and histidine, this study broadens the toolbox for designing tailored interfacial chemistries with applications in material and biomedical sciences.

Potentiometric determination of the local anesthetic procaine in pharmaceutical samples

In this study, a new potentiometric sensor was developed for the determination of the local anesthetic drug procaine in pharmaceutical samples. Procaine (Pr)–Tetraphenlyborate (TPB) ion–pair was synthesized and used as a sensor material. Potentiometric sensors using the synthesized ion pair (Pr–TPB), poly(vinyl chloride) (PVC) and o–nitrophenyloctyl ether (o–NPOE) in different proportions were prepared and their performance properties were tested. Among the prepared sensors, the best potentiometric response characteristics were obtained with the sensor composition Pr–TPB:PVC:o–NPOE in the ratio of 6.0:32.0:62.0 (w/w %). The new procaine sensor developed in the present study had a near–Nernstian behavior of 54.1 ± 3.3 mV/per decade and a low detection limit of 3.18 × 10−5 mol L−1 in the concentration range of 1.0 × 10−1–1.0 × 10−4 mol L−1. Additionally, the sensor had a response time of less than 10 s and could work in a wide pH range for two different concentration values without being affected by pH changes. Finally, the new procaine potentiometric sensor was used to detect procaine in injection samples and successfully determined procaine concentrations with high recoveries.

Fluorescent probe for imaging N2H4 in plants, food, and living cells and for quantitative detection of N2H4 in soil and water using a smartphone

Hydrazine is volatile and highly toxic, causing severe harm to water, soil, air, and organisms. Therefore, real-time detection and long-term monitoring of hydrazine are crucial for environmental protection and human health. Herein, an “OFF−ON” fluorescent probe 5-((10-ethyl-2-methoxy-10 H-phenothiazin-3-yl)methylene)−2,2-dimethyl-1,3-dioxane-4,6-dione (MPD) for hydrazine detection through a nucleophilic addition reaction was developed. MPD could exclusively identify hydrazine through colorimetric and fluorescent dual-channel responses within 30 s, which also demonstrated high sensitivity (detection limit, 12 nM) and a wide pH range (6 −12). The sensing mechanism of MPD was confirmed using theoretical calculations, where fluorescence was emitted following the recognition of hydrazine because of the disappearance of the photoinduced electron transfer (PET) process. Using a smartphone, MPD enabled the quantitative detection of hydrazine in real water samples and sandy soil. Notably, in the process of detecting hydrazine in actual water samples, the establishment of analytical methods and the completion of rapid quantitative detection only required a smartphone and built-in apps. Additionally, we showed that MPD could recognize hydrazine in various environmental samples, including plants, food, hydrazine vapors, and cells. We believe that the fluorescent probe MPD developed in this study and the established smartphone visualization platform will provide a convenient and effective tool for detecting hydrazine in environmental monitoring, food safety assessment, biological system safety, and other fields.

Multifunctional biomass-based solar evaporator with enhanced sterilization performance for solar-driven clean water evaporation

Solar-driven interfacial evaporation presents an important technology in dealing with the global freshwater crisis due to its highly effective solar-to-vapor conversion, minimal environmental impact, and off-grid application. However, the high material cost, complex fabrication process, and lack of effective sterilization limit its scaled-up application. Herein, we demonstrate an efficient multi-functional, biomass-based (MBB) photothermal evaporator using CuO nanoparticle-modified, carbonized peanut shells in a low-cost and scabble way. With highly efficient solar absorption, localized heating, and water transport, the MBB photothermal evaporator achieved a ∼ 91.1 % solar-to-vapor efficiency under sunlight illumination with a clean water production rate of 1.46 kg m−2 h−1. A similar evaporation rate of 1.41 kg m−2 h−1 was obtained directly from wastewater or seawater with a wide range of pH (2–14). The experiments showed that the collected water is relatively clean with complete removal of Escherichia coli and Staphylococcus aureus by damaging bacterial cell walls. 99 % of methylene blue and rhodamine B can also be effectively removed, benefiting from the formation of chelating and hydrogen bonds with the OH groups on the surface of MBB. This research provides a new environmentally sustainable photothermal evaporator for water purification, specifically designed to benefit economically stressed communities.

Efficient removal of chlortetracycline hydrochloride and doxycycline hydrochloride from aqueous solution by ZIF-67

ZIF-67 nanoparticles were synthesized by a simple method at room temperature and used to remove chlortetracycline hydrochloride (CTC) and doxycycline hydrochloride (DOX) from water. ZIF-67 was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) surface area, X-ray photoelectron spectroscopy (XPS), thermogravimetry (TGA) and zeta potential analyzer. The morphology and chemical composition of the synthesized ZIF-67 were characterized. The effects of key parameters such as pH, dosage, temperature, contact time, different initial concentrations and coexisting ions on the adsorption behavior were systematically studied. The results of batch adsorption experiments indicate that the adsorption process conforms to the pseudo-second-order kinetic model and Sips model. At 303K, the removal rates of CTC and DOX at 150 mg/L reached 99.16 % and 97.61 %, and the maximum adsorption capacity of CTC and DOX reached 1411.68 and 1073.28 mg/g, respectively. At the same time, ZIF-67 has excellent stability and reusability. Most importantly, the possible adsorption mechanism is proposed by exploring the changes of SEM, TEM, BET and FT-IR characterization results before and after the reaction, which mainly includes pore filling, electrostatic interaction and π-π interaction. The prepared ZIF-67 has a large specific surface area (1495.967 m2 g−1), achieves a high removal rate within a short time frame, and maintains a high removal rate across a wide pH range. These characteristics make ZIF-67 a potentially promising adsorbent for removing antibiotics from aqueous solutions.

A novel iron oxide (Fe3O4)-laden titanium carbide (Ti3C2) MXene stacks for the efficient removal of tetracycline from aqueous solution

Fe3O4 has the advantages of unique magnetic stability and low biological toxicity, which can improve pollutants separation efficiency. MXenes are two-dimensional materials and easy surface functionalization that can provide suitable carriers for Fe3O4. In this work, we synthesized magnetic MXene composites by a one-pot method that relies on doping Fe3O4 particles onto Ti3C2 MXene nanosheets by heat treatment. The Fe3O4/Ti3C2 MXene was analyzed by SEM, XRD, FTIR and XPS techniques, which showed that the material has good tetracycline (TC) removal properties and magnetic separation ability. The results showed that the adsorption capacity of it was 46.42 mg g−1, and the removal efficiency of 0.06 g adsorbent for 50 mL of 30 mg L−1 TC could reach 92.1% in a wide pH range of 4–10, when the adsorption temperature was 25 °C, and the adsorption time was 3 h. The adsorption data were consistent with Langmuir and the proposed second-order kinetic model, and the thermodynamic experiments confirmed that the adsorption of TC was a monolayer physicochemical adsorption coexisting heat-trapping process (ΔH = 15.72 kJ mol−1). In addition, the adsorption of TC by Fe3O4/Ti3C2 MXene was attributed to the synergistic effect of electrostatic attraction, hydrogen bonding and π-π packing. In conclusion, the saturation magnetization of Fe3O4/Ti3C2 MXene is 27.3 emu/g and it can not only be separated from water using its strong magnetic properties to avoid secondary contamination, but also can be used as a promising material to effectively remove antibiotics from aqueous media.

Biochemical Properties of a Novel Cold-Adapted GH19 Chitinase with Three Chitin-Binding Domains from Chitinilyticum aquatile CSC-1 and Its Potential in Biocontrol of Plant Pathogenic Fungi.

GH19 (glycoside hydrolase 19) chitinases play crucial roles in the enzymatic conversion of chitin and biocontrol of phytopathogenic fungi. Herein, a novel multifunctional chitinase of GH19 (CaChi19A), which contains three chitin-binding domains (ChBDs), was successfully cloned from Chitinilyticum aquatile CSC-1 and heterologously expressed in Escherichia coli. We also generated truncated mutants of CaChi19A_ΔI, CaChi19A_ΔIΔII, and CaChi19A_CatD consisting of two ChBDs and a catalytic domain, one ChBD and a catalytic domain, and only a catalytic domain, respectively. CaChi19A, CaChi19A_ΔI, CaChi19A_ΔIΔII, and CaChi19A_CatD exhibited cold adaptation, as their relative enzyme activities at 5 °C were 40.7, 51.6, 66.2, and 82.6%, respectively. Compared with CaChi19A and other variants, CaChi19A_ΔIΔII demonstrated a higher level of stability below 50 °C and retained relatively high activity over a wide pH range of 5-12. Analysis of the hydrolysis products revealed that CaChi19A and CaChi19A_ΔIΔII exhibit exoacting, endoacting, and N-acetyl-β-d-glucosaminidase activities toward colloidal chitin. Furthermore, CaChi19A and CaChi19A_ΔIΔII exhibited inhibitory effects on the hyphal growth of Fusarium oxysporum, Fusarium redolens, Fusarium fujikuroi, Fusarium solani, and Coniothyrium diplodiella, thereby illustrating effective biocontrol activity. These results indicated that CaChi19A and CaChi19A_ΔIΔII show advantages in some applications where low temperatures were demanded in industries as well as the biocontrol of fungal diseases in agriculture.

Efficient elimination of organic contaminants via a non-radical pathway involving activation of sulfite by synergistic adsorption-catalysis bifunctional chitosan-modified MOF derivative

Usually, Metal-based sulfite activation systems follow a radical generation pathway but are rare in non-radical pathways. Singlet oxygen (1O2) generation-targeted catalyst was synthesized by introducing non-redox metal oxides ZnO into chitosan-modified cobalt-zinc bimetallic oxides (CZ1.0C) via template method. Compared with Co3O4, the catalyst CZ1.0C coupled to the sulfite system (CZ1.0C/SO32-) maintained good adaptability in a common water background and a wide pH range (7–11). In addition, the CZ1.0C/SO32- system showed high efficiency in the degradation of Congo red (kobs = 0.190 min−1) and 100 % sulfite utilization. EPR, probe experiments, and DFT calculations proved the dominant role of 1O2, with a concentration three orders of magnitude higher than that of radicals. The controlled generation of non-radicals was achieved owing to the doping of ZnO and the conversion of lattice oxygen and oxygen vacancies. The catalytic oxidation intermediate HSO5- has also been demonstrated in the system, which achieves non-radical pathway oxidation through electron-mediated interactions. This article aims to develop a new “waste control by waste” strategy, which combines high selective adsorption and catalysis to achieve sulfur resource recovery and water pollutants elimination.

Efficient adsorption of hydroxychloroquine by carboxylated lignin-based sponge: Quantification of the adsorption contribution of interactions

Hydroxychloroquine (HCQ) as an antiviral pharmaceutical has been widely detected in the aquatic environment. Adsorption is an effective method for removal of HCQ, but the quantitative study of the adsorption interactions is unclear. In this study, a carboxylated lignin-based sponge (PLC) was fabricated, and the adsorption contributions of electrostatic attraction (EA), hydrogen bond (HB), and π-π electron donor–acceptor (π-π EDA) interactions were quantitatively investigated. The results showed that PLC exhibited excellent adsorption performance under wide pH range (4.0 < pH < 11.0), with the highest adsorption capacity of 0.165 mmol/g. Inhibitor and molecular probe experiments showed that EA and HB were the main contributors to adsorption at neutral and basic pH ranges, respectively. A linear correlation model of the carboxyl groups of lignin-based sponges with the adsorption capacity of EA, HB, and π-π EDA interactions of HCQ (R2 > 0.822) and three molecular probes (R2 > 0.749) was established, respectively. The optimal adsorption capacity was achieved by the synergistic combination of the deprotonated carboxyl of PLC with the HB of Ka1 amino, EA of Ka2 amino, and the π-π EDA of the quinoline ring. This study provided a new strategy for the quantitative construction of structure–activity relationships of adsorbents.

PH independent adsorption: Reusable zinc-ferrite nanospheres for the selective recovery of dyes from binary mixtures

Efficient separation of colorant pollutants is a formidable challenge, prompting research into innovative materials. We developed zinc-ferrite nanoparticles via the Microwave-Assisted Solvothermal Technique (MAST), exploiting judicious solvent compositions to enhance Lewis's acidity. Upscaling to gram batches yielded nanoparticles with a higher specific surface area (149 m2g−1). These nanoparticles demonstrated selective separation of dyes from binary mixtures, including Orange-G (OG), Fluorescein-Sodium (FSS), and Methyl-Orange (MO), with their high sorption rate fitting to the pseudo-second-order kinetic model. Langmuir isotherm for OG and MO were observed with respective adsorption capacity (qm) of 94.12 mg/g, 104.28 mg/g, whereas FSS more likely matched Sips isotherm with qm = 124.31 mg/g at natural pH in room temperature (27 °C). Desorption, reliant on solution pH and OH− ions, enabled efficient regeneration and multiple reuses without significant efficiency loss over five reuse cycles. Remarkably, selective separation was independent of surface charge and remained effective across a wide pH range and in the presence of common anions, namely I−, NO3−, C2H3O2− routinely encountered in dye effluents. This ecologically safe, scalable adsorbent offers a promising solution for expensive dye recovery.

Pancreatic lipase immobilization on cellulose filter paper for inhibitors screening and network pharmacology study of anti-obesity mechanism

The discovery of pancreatic lipase (PL) inhibitors is an essential route to develop new anti-obesity drugs. In this experiment, chitosan was used to add amino groups to cellulose filter paper (CFP) and then glutaraldehyde was used to covalently combine PL with amino-modified CFP through the Schiff base reaction. Under optimal immobilization conditions, CFP immobilized PL has a wide range of pH and temperature tolerance, as well as excellent reproducibility, reusability and storage stability. Subsequently, 26 natural products (NPs) were screened by immobilized PL with black tea extract having the highest inhibition rate. Three compounds with binding effects on PL (epigallocatechin gallate, theaflavin-3-gallate and theaflavin-3,3′-digallate) were captured. Molecular docking proved that these three compounds have a strong binding affinity for PL. Fluorescence spectra further revealed that theaflavin-3,3′-digallate could statically quench the intrinsic fluorescence of pancreatic lipase. The molecular docking and thermodynamic parameters indicated that electrostatic interaction was considered as the main interaction force between PL and theaflavin-3,3′-digallate. Finally, the potential anti-obesity targets and pathways of the three compounds were discussed through network pharmacology. This study not only proposes a simple and efficient method for screening PL inhibitors, but also sheds light on the anti-obesity mechanism of active compounds in black tea.

Efficient peroxydisulfate activation with γ-Al2O3-C-MIL-100(Fe) framework for sulfamethazine degradation: Enhanced oxidant utilization and reduced metal leaching

Low degradation efficiency and significant transition metal leaching are two challenges in persulfate activation systems based on metal-organic frameworks (MOFs) for organic pollutant degradation. Here, the challenges were solved by designing and synthesizing a micron-sized core-shell material, γ-Al2O3-C-MIL-100(Fe) (γACM), by coating the γ-Al2O3 core with carbon (γ-Al2O3-C) and futher modifying with MIL-100(Fe). Testing γACM with sulfamethazine (SMZ) demonstrated its outstanding peroxydisulfate (PDS) activation, achieving 92.5 % SMZ removal within 20 min at a low oxidant/pollutant ratio. Fe leaching from γACM was effectively inhibited, with only 3.59 % Fe lost after three recycles. The system showed adaptability across a wide pH range, and usability in sewage effluent, indicating promise for practical application. The hydrophobicity of γ-Al2O3-C, the coordinatively unsaturated sites in MIL-100(Fe), and the strong bounding of MIL-100(Fe) on γ-Al2O3-C ensured the effective SMZ gather, PDS activation, and Fe stability respectively, which led to the excellent performances of γACM.

Primary alcohol-induced coacervation in alkyl polyglucoside micellar solution for supramolecular solvent-based microextraction and chromatographic determination of phthalates in baby food

This study reports for the first time the phenomenon of supramolecular solvent formation based on alkyl polyglucoside as an amphiphile and primary alcohol as a coacervation agent. The physical properties (density, kinematic viscosity, phase diagram for ternary system) of the supramolecular solvent were investigated, and a mechanism for its formation was proposed. A green and simple microextraction procedure for preconcentration and determination of phthalates in baby foods packaged in plastic packaging was developed as proof-of-concept example. The microextraction procedure assumed separation of analytes from solid phase sample in micellar solution of decyl glucoside and in situ formation of supramolecular solvent for analytes preconcentration after addition of n-heptanol. The determination of phthalates in obtained extracts was implemented by high-performance liquid chromatography with UV–Vis detection. The limits of detection, calculated from a blank test based on 3σ, were determined to be 10 μg kg−1 for dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, and di-n-octyl phthalate. The developed procedure did not require filtration of sample suspension, and assumed the use of green and biodegradable substances for the supramolecular solvent formation across a wide pH range.

Biosurfactants as stabilizers of niclosamide nanocrystals: Enhancing stability, solubility, and cytotoxicity profiling

Biosurfactants are surface-active compounds of biological origin, stable over a wide range of temperature, pH, and salinity. In this work, the ability of the biosurfactants rhamnolipid (RAM), sophorolipid (SOFO) and surfactin (SURF) to stabilize a nanocrystal suspension of niclosamide (NCL) in water, and to enhance the drug solubility were evaluated. The performances were compared with those of the synthetic surfactants tween 80 (TW) and soluplus (SOLU). Overall, RAM, SOFO, and SURF proved to be as effective as TW and SOFO in terms of NCL nanocrystal suspension stabilization. Formulations containing 3 % (w/w) surfactant exhibited the best stability at 4 °C and 25 °C. The three biosurfactants also led to an improvement of aqueous NCL solubility, even when a slurry of the micronized drug was used without nanocrystal formulation. The best performance was observed for the SURF 3 % (w/w) nanocrystal formulation (1157.48 μg/mL), which released more than twice the amount of NCL compared to the best synthetic surfactant formulation (TW 3 % (w/w), 542.57 μg/mL), and 622 times more than the pure solid drug (1.86 μg/mL). Cell viability was not compromised by the surfactants alone, indicating that the formulation cytotoxic effect is related to the enhanced solubilization of NCL. Consistently, the NCL/SURF formulation was the most effective, achieving a maximum cytotoxicity effect of 80 % at a concentration of 1000 nM, while the other formulations reached a maximum effect of 71 % at concentrations starting from 1500 nM. Nevertheless, when the balance between formulation stability, drug release enhancement, and cytotoxicity is considered the three biosurfactants studied in this work showed significant potential advantages relative to synthetic analogues that can be explored in pharmaceutical development.

Carbon quantum dots assemblies integrated with spatial confined Co nanoparticles for antibiotic degradation via peroxymonosulfate activation

Heterogeneous Co-based materials are well-known for their exceptional catalytic properties in activating peroxymonosulfate (PMS) for the degradation of antibiotic pollutants. However, the potential applications of these materials are often hindered by significant Co nanoparticle aggregation and ion leaching. In this study, a carbon quantum dot-mediated self-assembly strategy was used to fabricate three-dimensional porous sponge-like Co@CDs-x (x represents the calcination tempeatures) catalysts with spatially confined Co nanoparticles. Among the samples, Co@CDs-900 exhibited a remarkable 97.8 % removal efficiency of TC in 11 minutes, with an apparent rate constant of 0.313 min−1. The exceptional performance of Co@CDs-900/PMS can be attributed to its large specific surface area, unique porosity, and abundant catalytically active sites, which generate ample reactive oxygen species for TC degradation. The catalyst demonstrated good degradation capabilities across a wide pH range of 3–11 and various organic pollutants such as tetranitrophenol, oxytetracycline, ciprofloxacin, methyl orange, and rhodamine B. Moreover, Co@CDs-900 maintained high activity even after the 5th cycle due to its magnetic property and spatial confinement effect, preventing catalyst loss and ion leaching during recycling tests. The degradation mechanism involved both free-radical and non-free radical pathways, with SO4•− and 1O2 identified as the primary reactive oxygen species. The degradation intermediates of TC were identified and a plausible degradation pathway was proposed. Toxicity assessment revealed that the Co@CDs-900/PMS system effectively reduced the toxicity of TC post-degradation. This study presents an effective approach for developing sponge-like CDs assemblies with spatially confined metal nanoparticles for activating PMS in antibiotic degradation.

Non-radical activation of persulfate by CuO catalyst for degradation of antibiotics

Advanced oxidation process (AOP) based on persulfate (PS) activation has attracted numerous attentions for antibiotic elimination due to the high stability and low cost of PS. In this work, a non-radical activation of PS by CuO catalyst was developed to efficiently degradation of antibiotics. Employing moxifloxacin (MOX) as model pollutant, the CuO/PS system showed excellent degradation rate for 100 mg L−1 MOX that is 13.2 and 7.7 times higher for than the single CuO and PS, and meanwhile the performance is also much better than the typical AOP heterogeneous catalyst Fe2O3 in both neutral and acidic solutions. The optimization experiments indicate the optimal PS concentration is 2.5 mM, and the CuO/PS system can work in a wide pH range for different MOX concentrations. Furthermore, the CuO catalyst has high structural stability and catalytic durability, and the CuO/PS system has good practicality that can degrade a variety of antibiotics and be used in different aquatic environments. Based on various characterizations, a non-radical PS activation route on the CuO surface was proposed. Finally, toxicity assessment of the detected intermediates implies that the toxicity and the potential risk to the environment were effectively decreased. This work testifies PS can be efficiently activated by CuO through a non-radical pathway and presents superior performance for antibiotic elimination.

Deep Reconstruction of Ruthenate Perovskite Oxide Enables Efficient pH-Universal Hydrogen Evolution Reaction.

Designing highly efficient, stable, and pH-universal perovskites for hydrogen evolution reaction (HER) is urgently needed yet remains a grand challenge. Herein, a titanium-containing strontium ruthenate (SrTi0.5Ru0.5O3, STRO) is developed as an excellent HER electrocatalyst in a wide pH range. The introduction of Ti into SrRuO3 significantly reduces the size of STRO, endowing with a high reactivity that facilitates a deep surface-reconstruction during HER. Furthermore, Sr2+ leaching triggered reconstruction leads to STRO breaking into tiny nanoparticles accompanied by high-valence ruthenium (Ru) species reducing to metallic Ru. The generated active species, increased accessible sites, and improved electrical conductivity greatly boost HER. The reconstructed STRO displays remarkable HER activities with exceptional low overpotentials of 18, 24, and 55mV at 10mA cm-2 in 1m KOH, 0.5m H2SO4, and 1m PBS, respectively, surpassing most perovskites reported previously and comparable to or even outperforming that of commercial Pt/C. Moreover, the STRO exhibits excellent stabilities over 200h in alkaline and acidic media, superior to that of Pt/C. This work not only provides insights into structure reconstruction of perovskites during HER, but also opens new perspectives for developing high-efficiency and pH-universal electrocatalysts for future energy applications.

Molecular identification of rhamnolipids produced by Pseudomonas oryzihabitans during biodegradation of crude oil.

The ability to produce biosurfactants plays a meaningful role in the bioavailability of crude oil hydrocarbons and the bioremediation efficiency of crude oil-degrading bacteria. This study aimed to characterize the produced biosurfactants by Pseudomonas oryzihabitans during the biodegradation of crude oil hydrocarbons. The biosurfactants were isolated and then characterized by Fourier transform infrared (FTIR), liquid chromatography-mass-spectrometry (LC-MS), and nuclear magnetic resonance spectroscopy (NMR) analyses. The FTIR results revealed the existence of hydroxyl, carboxyl, and methoxyl groups in the isolated biosurfactants. Also, the LC-MS analysis demonstrated a main di-rhamnolipid (l-rhamnopyranosyll-rhamnopyranosyl-3-hydroxydecanoyl-3-hydroxydecanoate, Rha-Rha-C10-C10) along with a mono-rhamnolipid (l-rhamnopyranosyl-b-hydroxydecanoylb-hydroxydecanoate, Rha-C10-C10). In agreement with these findings, the NMR analysis confirmed the aromatic, carboxylic, methyl, sulfate moieties, and hexose sugar in the biosurfactants. The emulsion capacity of the biosurfactants decreased the surface tension of the aqueous system from 73.4 mN m-1 to around 33 mN m-1 at 200 mg L-1 as the critical micelle concentration. The emulsification capacity of the biosurfactants in the formation of a stable microemulsion for the diesel-water system at a wide range of pH (2-12), temperature (0-80°C), and salinity (2-20 g L-1 of NaCl) showed their potential use in oil recovery and bioremediation through the use of microbial enhancement. This work showed the ability of Pseudomonas oryzihabitans NC392 cells to produce rhamnolipid molecules during the biodegradation process of crude oil hydrocarbons. These biosurfactants have potential in bioremediation studies as eco-friendly and biodegradable products, and their stability makes them optimal for areas with extreme conditions.