High-performance Liquid Chromatography-mass Spectrometer Research Articles

Mechanism of enhanced degradation of antibiotic wastewater by three-dimensional electrocatalytic oxidation system: Coconut shell biochar as particle electrode

A porous particle electrode, coconut shell biochar (CBC), was prepared using coconut shell as raw material and applied to the treatment of tetracycline (TC) wastewater. Exploring the three-dimensional electrocatalytic oxidation system using a series of key factors such as pH (2−10), current density (20–60 mA/cm2), CBC particle size (0.88–2.36 mm), CBC dosage (3–13 g/L), electrolyte concentration (5000–10,000 mg/L), and electrode spacing (3–5 cm). The optimal conditions for these parameters were 10, 50 mA/cm2, 1.4–1.7 mm, 7 g/L, 8000 mg/L, and 4 cm. Under these conditions, the degradation of TC conformed to pseudo-first-order kinetics. The chemical oxygen demand (COD) and TC removal rates reached 84.01 % and 99.18 % within 45 min, while the two-dimensional system only achieved 29.27 % and 39.83 %, respectively. The degradation mechanism of TC was determined based on the production of H2O2 and •OH. The adsorbed saturated CBC might be regenerated through electrochemical reactions, inducing further adsorption, and forming numerous micro electrolysis cells to promote the production of free radicals, thereby boosting TC mineralization. Finally, the high-performance liquid chromatography-mass spectrometer was applied to identify the transformation products and degradation pathways of TC. Additionally, the CBC still showed excellent catalytic degradation effect after being reused for 4 times. Therefore, this study makes it possible to prepare an efficient and low-cost electrocatalyst for the treatment of antibiotic wastewater, as well as for further understanding the electrocatalytic mechanism, conversion products, and degradation pathways of TC in wastewater.

Mechanism of enhanced degradation of antibiotic wastewater by three-dimensional electrocatalytic oxidation system: Coconut shell biochar as particle electrode

A porous particle electrode, coconut shell biochar (CBC), was prepared using coconut shell as raw material and applied to the treatment of tetracycline (TC) wastewater. Exploring the three-dimensional electrocatalytic oxidation system using a series of key factors such as pH (2−10), current density (20–60 mA/cm2), CBC particle size (0.88–2.36 mm), CBC dosage (3–13 g/L), electrolyte concentration (5000–10,000 mg/L), and electrode spacing (3–5 cm). The optimal conditions for these parameters were 10, 50 mA/cm2, 1.4–1.7 mm, 7 g/L, 8000 mg/L, and 4 cm. Under these conditions, the degradation of TC conformed to pseudo-first-order kinetics. The chemical oxygen demand (COD) and TC removal rates reached 84.01 % and 99.18 % within 45 min, while the two-dimensional system only achieved 29.27 % and 39.83 %, respectively. The degradation mechanism of TC was determined based on the production of H2O2 and •OH. The adsorbed saturated CBC might be regenerated through electrochemical reactions, inducing further adsorption, and forming numerous micro electrolysis cells to promote the production of free radicals, thereby boosting TC mineralization. Finally, the high-performance liquid chromatography-mass spectrometer was applied to identify the transformation products and degradation pathways of TC. Additionally, the CBC still showed excellent catalytic degradation effect after being reused for 4 times. Therefore, this study makes it possible to prepare an efficient and low-cost electrocatalyst for the treatment of antibiotic wastewater, as well as for further understanding the electrocatalytic mechanism, conversion products, and degradation pathways of TC in wastewater.

Liquid residue analysis of Chinese bronze vessel of the Han Dynasty

The bronzeware ‘Fang’ was prevalently used as a liquor vessel during the late Warring States and the Han Dynasty (202 BCE–220 CE). In this paper, the liquid collected from a ‘Fang’ vessel of the Han Dynasty was analyzed by scientific techniques including high performance liquid chromatograph mass spectrometer (HPLC-MS), high-throughput sequencing (HTS) and polarizing microscope (PM). A variety of organic compositions, microbial communities and damaged starch grains were identified, suggesting the liquid is presumably the residue of liquor produced through cereal-based fermentation. Upon examing the historical literatures, the residue is speculated to be millet liquor made by following the procedures of immersing and steaming raw material, adding wheat yeast, stirring, saccharifying, fermenting, etc. The taste of the liquor is assumed to be mild, with a blend of sweet, slightly sour, and bitter taste. This paper can yield new insight into the research of archaeological organic remains and provide evidence for exploring the brewing technology of the Han Dynasty.

Novel MIL-88B(Fe)/ZnTi-LDH high-low junctions for adsorption and photodegradation of tetracycline: Characteristics, performance, and mechanisms

In this paper, a high-efficient MIL-88B(Fe)/ZnTi-LDH high-low junction photocatalyst was successfully prepared by a simple method for the photodegradation of tetracycline (TC). The combination of MIL-88B(Fe) and ZnTi-LDH created an internal electric field and high-low junction, facilitated the separation of carriers, and thus enhanced photocatalytic activity. The optimized MZ-30% sample showed the highest photocatalytic degradation of TC about 93.51%. The photocatalytic kinetic removal rate of MZ-30% reached 0.0941 min−1, 31.36 times of MIL-88B(Fe) (0.003 min−1) and 1.7 times of ZnTi-LDH (0.0550 min−1). Furthermore, MZ-30% possessed the highest adsorption capacity for TC (543.89 mg/L). The effects of co-existing ions, initial pH, water source, and humic acid (HA) on TC degradation were examined. The main active substances of MIL-88B(Fe)/ZnTi-LDH in photocatalytic reaction were 1O2, h+, and ·O2- confirming by reactive species elimination experiment and electron spin resonance (ESR) tests. The molecular structure and toxicity of intermediates were investigated by a high-performance liquid chromatography-mass spectrometer (HPLC-MS) and Toxicity Estimation Software Tool (T.E.S.T), and the possible degradation pathway of TC was revealed. The results highlight that MIL-88B(Fe)/ZnTi-LDH high-low junction composite is a desirable photocatalyst for removing antibiotics and other emerging contaminants in water.

Insights into the Molecular Motion of Benzotriazole in the Volatile Corrosion Inhibitor Packaging: A Detection and Mass Transfer Study

A new methodology using microwave extraction, gas-diffusion microextraction (GDME) and high-performance liquid chromatography-mass spectrometer (HPLC-MS) was developed for the analysis of the quantitative detection of gaseous and solid benzotriazole (BTA) and the mass transfer behavior of BTA in volatile corrosion inhibitor (VCI) packaging. The best extraction conditions of BTA in the VCI films were obtained, and the vapor pressure of BTA in the VCI packaging was detected and characterized by a mathematical model using the new methodology. The migration content of BTA in the VCI films and the BTA content on the surface of the films were detected, and the diffusion coefficients at three temperatures were calculated. The vapor pressure and diffusion coefficients of BTA increased with increasing temperature, and the volatilization of BTA promoted the migration of BTA from the VCI films. Moreover, a molecular dynamics (MD) simulation was performed to determine the migration of the BTA molecules within the VCI films at three temperatures; the overall trend of the experimental values was the same and the simulated values were generally within two orders of magnitude of the corresponding experimental values, with the difference likely due to the ignoring of the crystallinity of LDPE.

Profiling of carbonyl compounds in fresh cabbage with chemometric analysis for the development of freshness assessment method

Abstract The aim of this study was to screen the distribution of carbonyl compounds (CCs) in fresh cabbage as a sample model of multi-layered leafy vegetables for discovering the universal freshness marker of fresh produces. The distribution of CCs was observed in the three outer leaf layers of the cabbage. The profile of CCs in each leaf will guide the selection of which leaf is the appropriate part to be used to further discover a freshness marker of cabbage during storage treatment at the postharvest stage. The carbonyl compounds in each leaf were extracted using a mixture of chloroform and methanol (2:1). The extracted CCs from samples were derivatized with dansyl hydrazine. A high-performance liquid chromatography-mass spectrometer with multiplexed multiple reactions monitoring (MRM) was used for the comprehensive detection of carbonyl compounds. More than 400 peaks were observed in the MRM chromatogram from all leaves. The distribution of m/z values that represent CCs were analyzed employing the principle component analysis-discriminant analysis by relating it to the leaf position. The distribution of CC was different for each leaf where the leaves of the second and third layers were similar and significantly different from the leaves of the first layer. The accumulation of trans-2-hexenal was dominant in the first layer; therefore, the utilization of the first layer is not suitable as the part of the sample to discover the freshness marker of multi-layered leafy vegetables.

Rationally designed C-PANI/BiOBr STEP-scheme heterojunction photocatalyst for boosting photodegradation of 17β-estradiol

17β-estradiol (E2) in natural water has caused serious environmental problems because of its extremely high estrogenic activity. Herein, a novel β-CD@PANI/BiOBr (C-PANI/BiOBr) step scheme (S-scheme) heterojunction photocatalyst was successfully prepared via facile chemical precipitation method. The encapsulation of β-cyclodextrin (β-CD) around polyaniline (PANI) contributed to better transfer of photogenerated carries by the stabilization of radical cation and excellent adsorption capability driven by hydrophobic interaction, hydrogen bonding and π-π stacking. The C-PANI/BiOBr heterojunction photocatalysts realized excellent light absorption in full spectrum. The N derived from C-PANI could coordinate with Bi metal ions, which favored forming BiOBr with (110) facet exposure, thus promoting the photogenerated electron-hole separation. The optimal 20% C-PANI/BiOBr achieved rapid degradation of contaminants (100% removal of E2 in 40 min and RhB in 9 min) under visible light irradiation. Furthermore, three main degradation pathways of E2 photodegradation were proposed by high performance liquid chromatography-mass spectrometer (HPLC-MS) results, and the toxicity of E2 and intermediates were evaluated by ECOSAR program. The active species capture experiment indicated that h+ and •O2– played the dominated roles in the photodegradation process and S-scheme mechanism of C-PANI/BiOBr with enhanced photocatalytic performance was also revealed. This study provided an insight in fabricating efficient photocatalysts for environmental remediation.

Influence of octreotide on apoptosis and metabolome expression in lipopolysaccharide-induced A549 cells

Abstract Lung cancer shows a high rate of incidence and mortality. This study aimed to investigate the influence of octreotide (OCT) on lipopolysaccharide (LPS)-induced apoptosis and metabolome expression in A549 cells. After A549 cells were treated by LPS or co-cultured with LPS and OCT, cell apoptosis was tested by flow cytometry, and gas chromatography-mass spectrometer (GC/MS) and high-performance liquid chromatography-mass spectrometer (LC/MS) were subjected to determine the differently expressed metabolites, and the interaction network was constructed. Results found that OCT promoted the apoptosis of A549 cells and significantly affected LPS-regulated cell apoptosis. Following the further investigation by orthogonal partial least squares discriminant analysis (OPLS-DA), the metabolites with different expression levels were obtained, and most of which belong to amino acids, phospholipids, organic acid, and saccharides. Fourteen components with the role of the marker metabolites included serotonin, indole, threonine, serine, glucose, phenylalanine, lactose, fumarate, 4-hydroxyphenyllactate, aspartate, asparagine, putrescine, proline, and succinate. It is indicated that OCT promotes apoptosis through five metabolism pathways and 14 key metabolism elements in A549 cells.

Ultrathin fluorine-doped TiO2(B) nanosheets-anchored hierarchical cog wheel-shaped NH2-MIL-53(Al) for boosting photocatalytic activity

Developing novel S-scheme systems with highly active solar-driven catalysts are of huge interest in degrading noxious antibiotics in a sustainable manner. Herein, fluorine (F)-doped TiO2(B) nanosheets-modified gear-shaped NH2-MIL-53(Al) were first fabricated for tetracycline degradation. Benefiting from the synergy among the incorporated F species, well-matched band structure, and built-in electric field, the optimized nanohybrid attains an impressive degradation rate (94.6 %) and TOC mineralization efficiency (71.4 %). Moreover, the addition of external interferential ions, such as Cu2+ or NO3− nearly have no influence on the photoactivity. A probable degradation pathway was proposed on the basis of the calculated Fuki indexes and prime intermediates identified by a high-performance liquid chromatography-mass spectrometer. On NH2-MIL-53(Al)/F-TiO2(B) interfaces, the migration of electrons from F-TiO2(B) to NH2-MIL-53(Al) via intense electronic interactions contribute to a S-scheme mode, which is conductive to facilitating rapid spatial charge separation, superior visible light utilization, and populated exposed active sites with high potentials. This study paves new avenues to an atomic-scale interfacial engineering of S-scheme heterojunctions for efficient water purification.

Variability and chemical composition of the extractive content of woody residues from three European orchard species: apricot (Prunus Armeniaca L.), olive (Olea Europea L.), and orange trees (Citrus Sinensis L.)

AbstractBackgroundThe huge quantity of agricultural biomass has led Europe to issue directives to ensure that it is properly managed. Among the permanent European crops area, olive, orange, and apricot orchards are the most present. The management of these crops produces significant amounts of biomass, which very often is burned in the field. With a view to the circular economy, this study aims to analyze the secondary metabolites present in the biomass of these three crops.ResultsSecondary metabolites were extracted from wood and bark by an Accelerated Solvent Extractor at 120° using water, ethanol, and a mixture of water and ethanol as solvents. In addition, the identification of the molecules present in the extracts was attempted using high‐performance liquid chromatography (HPLC) coupled with a mass spectrometer (MS). The analysis showed that in the three crops, the highest yields of extract were measured in the bark while the species that has shown the highest yield compared to the others was the olive tree. HPLC–MS technique revealed interesting molecular compounds, such as catechins, epicatechins, and oleuropein, respectively in the apricot and olive extracts.ConclusionThe biomass extractives of these three species highlighted an interesting potential for applications in various industrial sectors such as for example, pharmaceutical, nutraceutical, and agriculture.

Age-related changes in the ratio of Type I/III collagen and fibril diameter in mouse skin.

The content of type I collagen (COL-I) and type III collagen (COL-III) and the ratio between them not only affect the skin elasticity and mechanical strength, but also determine the fibril diameter. In this research, we investigated the age-related changes in COL-I/COL-III ratio with their formed fibril diameter. The experimental result was obtained from high performance liquid chromatography-mass spectrometer, hydroxyproline determination, picrosirius red staining and transmission electron microscopes (TEM), respectively. The result indicated that the COL-I/COL-III ratio in mouse skin increased with aging. From the 0th to 9th week, the COL-I/COLIII ratio increased from 1.3:1 to 4.5:1. From the 9th to the 18th week, it remained between 4.5:1 and 4.9:1. The total content of COL-I and COL-III firstly increased and then decreased with aging. The TEM result showed that the fibril diameter increased with aging. From the 0th to 9th week, the average fibril diameter increased from 40 to 112 nm; From the 9th to 18th weeks, it increased from 112 to 140 nm. After the 9th week. The fibril diameter showed obvious uneven distribution. Thus, the COL-I/COLIII ratio was proportional to the fibril diameter, but inversely proportional to the uniformity of fibril diameter.

Degradation of the nonylphenol aqueous solution by strong ionization discharge: evaluation of degradation mechanism and the water toxicity of zebrafish.

Nonylphenol (NP) is a typical environmental endogenous disrupter with low concentration and high toxicity. This paper describes the mechanism of NP degradation in solution by strong ionization dielectric barrier discharge (SIDBD). Furthermore, the degradation performance of NP by SIDBD was tested by changing the equipment voltage, the initial concentration of NP in aqueous solution, pH, and inorganic ions. Degradation pathways of NP were detected using a high-performance liquid chromatography-mass spectrometer. The biological effects of NP degradation were assessed by detecting indicators of embryonic development in zebrafish (survival rate, fetal movement, heartbeat, the body length, behavior, deformity) and adult fish (sex differentiation, weight, ovarian testes pathological section analysis). The results showed when the input O2 was 5 L/min and the voltage was 3.2 kV, the degradation efficiency of NP can reach 99.0% after 60 min of experiment. Equipment voltage, initial concentration of NP in solution, pH, inorganic ions and other factors can influence the degradation efficiency of NP by DBD. At the higher concentration of NP, the greater influence on embryonic development in zebrafish was noticed. Although the effects of NP on zebrafish sex differentiation were not obvious, it showed significant male weight inhibition and decrease in sperm number.

Eu/GO/PbO2 composite based anode for highly efficient electrochemical oxidation of hydroquinone

Herein, a novel europium/graphene oxide/lead oxide (Eu/GO/PbO2) composite based anode with excellent electrocatalytic performance towards degradation of hydroquinone was prepared by a facile co-electrodeposition method. The composition and micromorphology of the anode was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) and the results confirmed that europium (Eu) and graphene oxide (GO) were successfully composited with PbO2 and a more compact structure was obtained, which was conductive to enhancing the corrosion resistance of the electrode. Besides, electrochemical measurements indicated that Eu/GO/PbO2 electrode possessed longer service lifetime (87 h), higher oxygen evolution potential (2.64 V), and lower charge transfer resistance (41.08 Ω) than GO/PbO2 and pure PbO2 electrode. The promoted electrocatalytic activity of Eu/GO/PbO2 electrode was ascribed to its stronger hydroxyl radical generation ability, more active sites and lower electron transfer resistance. Additionally, effects of initial hydroquinone concentration, applied current density and initial pH value on the degradation performance of Eu/GO/PbO2 anode were systematically investigated. The behind degradation mechanism of hydroquinone by Eu/GO/PbO2 anode was speculated on the basis of the major intermediates identified by high performance liquid chromatography-mass spectrometer (HPLC-MS). Under the continuous attack of free hydroxyl radicals, hydroquinone was finally decontaminated into CO2 and H2O. The present work demonstrated that Eu/GO/PbO2 composite anode exhibited excellent degradation performance towards hydroquinone.

Carbon nitride coupled with Ti3C2-Mxene derived amorphous Ti-peroxo heterojunction for photocatalytic degradation of rhodamine B and tetracycline

Exploring the solar-driven photocatalyst for antibiotic and dye degradation has been confronted with a great challenge. In this study, a novel and original photocatalyst derived from the g-C3N4/amorphous Ti-peroxo complexes (CATC) heterojunction was successfully synthesized towards Rhodamine B (RhB) and tetracycline (TC) degradation under visible light irradiation (λ>420 nm). Based on the special photocatalytic activity, Ti3C2-Mxene acted as the starting precursor of amorphous Ti-peroxo complexes via one-step H2O2 oxidation route. Multiple characterization techniques were applied to explore the crystal structure, element composition, and photoelectrochemical property of photocatalyst. As expected, the modified photocatalyst possessed a favorable photocatalytic performance towards the preferable reaction rate for RhB (0.0483 min−1) and TC (0.0208 min−1) degradations, which were 16.65 times and 69.3 times higher than that of pure g-C3N4 (CN) material, profiting from the generated direct Z-scheme heterojunction with favorable redox capacity. Here, h+,∙O2- and ∙OH were verified as typical active radicals for RhB and TC degradation through free radical quenching experiments and electron spin resonance characterization. Degradation intermediate products were also confirmed by high performance liquid chromatography–mass spectrometer (HPLC-MS). The effects of initial pH and ionic strength on RhB and TC photocatalytic degradation performances were discussed. In addition, a preferable reusability and stability performance ensured the modification photocatalyst had a great application potential in wastewater treatment. This study provided a unique avenue through one-step method for the construction of g-C3N4 and Mxene based photocatalyst towards the degradation of antibiotics and dyes from wastewater.

Influence of the Lignin Extraction Methods on the Content of Tricin in Grass Lignins

Tricin as a monomer of grass lignin with unique biological properties is beneficial to human health with the potential for various applications. The abundant grass lignin could be an alternative source for tricin if an effective separation method is available. In this study, we used different lignin preparations, including alkali lignin (AL), mild acidolysis lignin (MAL), cellulase enzymatic lignin (CEL), γ-valerolactone lignin (GVL), and organosolv lignin (OL), to investigate the effect of different fractionation methods on the tricin content of the wheat straw lignin. The tricin signal of different lignins can be clearly identified by 2D heteronuclear singular quantum correlation (HSQC) spectra. GVL showed the highest tricin level among these lignin samples as the tricin content of GVL was accounted to be 8.6% by integrals. The tricin content was carefully determined using thioacidolysis combined with high-performance liquid chromatography-mass spectrometric (HPLC-MS), and the quantitative results of tricin by HPLC-MS were basically consistent with that of 2D HSQC integrals. Both methods have proved that the tricin contents of lignins isolated under acid conditions were significantly higher than that of AL. In addition, the determination of the sun protection factors (SPF) of lignin-based sunscreen and antioxidant activity of lignin preparations indicated that reserving more tricin was beneficial to the UV resistance of lignin samples. Therefore, this study not only provides new insights for the extraction methods of lignin with high tricin content but also is beneficial to the future study on the application of tricin and tricin-lignin.

Facile construction of novel organic–inorganic tetra (4-carboxyphenyl) porphyrin/Bi2MoO6 heterojunction for tetracycline degradation: Performance, degradation pathways, intermediate toxicity analysis and mechanism insight

Developing durable photocatalysts with highly efficient antibiotics degradation is crucial for environment purification. Herein, tetra (4-carboxyphenyl) porphyrin (TCPP) was loaded onto the surface of Bi2MoO6 microspheres to gain hierarchical organic–inorganic TCPP/Bi2MoO6 (TCPP/BMO) heterojunctions via a facile impregnation strategy. The catalytic properties of these catalysts were comprehensively investigated through the photodegradation of tetracycline hydrochloride (TC) under visible light. Among all the TCPP/BMO heterojunctions, the highest photodegradation rate constant (0.0278 min−1) was achieved with 0.25 wt% TCPP (TCPP/BMO-2), which was approximately 1.15 folds greater than that of pristine Bi2MoO6 and far superior to pure TCPP. The extremely high photocatalytic performance is attributed to the interfacial interaction between TCPP and Bi2MoO6, which favors the efficient separation of charge carriers and the enhancement of visible-light absorbance. TCPP/BMO-2 possesses high mineralization capability and good recycling performance. Photo-induced O2–, h+, and OH were mainly responsible for the degradation of TC. The degradation pathways of TC and toxicity of degradation intermediates were analyzed based on the intermediates detected by the high performance liquid chromatography-mass spectrometer (HPLC–MS) and the toxicity assessment by the quantitative structure–activity relationship (QSAR) prediction. A possible photocatalytic mechanism over TCPP/BMO is proposed. This work offers an insight in developing the porphyrin-based organic–inorganic heterojunctions for effectively remedying pharmaceutical wastewater.

Elevated levels of urine isocitrate, hydroxymethylglutarate, and formiminoglutamate are associated with arterial stiffness in Korean adults

Recent evidence suggests that cellular perturbations play an important role in the pathogenesis of cardiovascular diseases. Therefore, we analyzed the association between the levels of urinary metabolites and arterial stiffness. Our cross-sectional study included 330 Korean men and women. The brachial-ankle pulse wave velocity was measured as a marker of arterial stiffness. Urinary metabolites were evaluated using a high-performance liquid chromatograph-mass spectrometer. The brachial-ankle pulse wave velocity was found to be positively correlated with l-lactate, citrate, isocitrate, succinate, malate, hydroxymethylglutarate, α-ketoisovalerate, α-keto-β-methylvalerate, methylmalonate, and formiminoglutamate among men. Whereas, among women, the brachial-ankle pulse wave velocity was positively correlated with cis-aconitate, isocitrate, hydroxymethylglutarate, and formiminoglutamate. In the multivariable regression models adjusted for conventional cardiovascular risk factors, three metabolite concentrations (urine isocitrate, hydroxymethylglutarate, and formiminoglutamate) were independently and positively associated with brachial-ankle pulse wave velocity. Increased urine isocitrate, hydroxymethylglutarate, and formiminoglutamate concentrations were associated with brachial-ankle pulse wave velocity and independent of conventional cardiovascular risk factors. Our findings suggest that metabolic disturbances in cells may be related to arterial stiffness.

Synergistic catalytic Fenton-like degradation of sulfanilamide by biosynthesized goethite-reduced graphene oxide composite

A series of goethite (Gt)-graphene (rGO) composites (Gt-rGO) having different rGO contents (2%–10%) was biologically prepared under mild conditions with Acidovorax sp. BoFeN1 and exhibited comparable or even higher catalytic efficiencies upon sulfonamides degradation than most known chemically synthesized catalysts. Pseudo-first-order rate constant of sulfanilamide degradation (60 μM, 0.971 h−1) in the system mediated by Gt-rGO with the optimal rGO content of 6% was 6.7, 15.4 and 168.1 folds higher than those in the control rGO/H2O2, Gt/H2O2 and H2O2 systems, respectively. Excellent synergistic catalytic effects between Gt and rGO in Gt-rGO were identified in four continuous cycles. The Gt-rGO systems exhibited more efficient •OH generation, H2O2 decomposition and Fe(II) accumulation rates than the control Gt or rGO systems. Fast Fe(III)/Fe(II) cycling was obtained in the Gt-rGO systems, which might be due to the strong Fe−C coordination and the decrease of rGO aggregation and Gt particle sizes. Additionally, Gt particles in Gt-rGO exposed more defects as active sites for H2O2 activation. High-performance liquid chromatography-mass spectrometer analysis suggested that sulfanilamide was gradually degraded through hydroxylation, C−N cleavage and benzene ring opening. The results provided a new approach for the tailored design of eco-friendly, cost-effective and efficient iron (oxyhydr)oxides-graphene catalysts for contaminants elimination.

Aquaculture drug degradation in persulfate by PANI-based microparticles controlled via ultrasonic field: Forced motion of “burning hot micromotors”

The triphenylmethane derivative malachite green (tpmMaG) despite repeated prohibitions but is frequently detected in aquatic environment and draws emerging attention because of the potential poisonous effects. The polyaniline/persulfate with ultrasound catalysis (US/PANI-PS) was developed for tpmMaG removal. The effects of 12 factors and the optimization by response surface methodology (RSM) for tpmFG removal were evaluated based on the pseudo-first-kinetics (kobs). From free radical inhibition, the ratios of active species in US/PANI-PS (δ11 = 0.355, δ12 = 0.593) were close to that in US-PS (δ21 = 0.346, δ22 = 0.586) and different to that in PANI-PS and PS systems. A possible degradation pathway (hydroxylation, N-demethylation, deamination, and open-benzene ring) was explored by gas chromatography-mass spectrometer (GC/MS) and high performance liquid chromatography-mass spectrometer (HPLC-MS). The designed reactor involving the US-driven PANI was simulated by acoustic-piezoelectric interaction. From cavitation calculations, the estimated effective-mean temperature at bubble-water interface had little increasing (from 704 K to 711 K) after adding the PANI, however, the adsorption capacity of tpmMaG in reactive zone decreased from 0.0891 μM to 0.0787 μM. The mechanism (PANI hot turbo-micromotors) with US/PANI-PS was proposed. The tpmMaG was removed with a low treatment cost of 2.81 $⋅m−3 (the EE/O value 18.29 kWh⋅m−3) by US/PANI-PS, presenting a cost-effective treating process. The reusability tests and characterizations (contact angle, X-ray diffraction (XRD), and scanning electron microscope (SEM)) further confirmed the stability of PANI.

Construction of BiOCl/CuBi2O4 S-scheme heterojunction with oxygen vacancy for enhanced photocatalytic diclofenac degradation and nitric oxide removal

Construction of step-scheme (S-scheme) heterojunction with superior redox ability is emerging to be an efficient way to develop high-efficiency photocatalysts for environmental pollution control. Herein, a new S-scheme heterojunction photocatalyst built from BiOCl with oxygen vacancies and CuBi2O4 was developed. Compared to pristine CuBi2O4 and BiOCl, this S-scheme heterojunction photocatalysts (BOC/CBO) show enhanced photocatalytic performance in removing aqueous diclofenac (DCF) and gaseous nitric oxide (NO) under visible light irradiation, which is mainly ascribed to the improved charge separation and transfer and redox ability by the S-scheme heterojunction structure and the enhanced catalytic oxidation by tunning the coordination structure and electronic states of O2 by oxygen vacancies. Further, the detailed DCF degradation pathways were studied and confirmed by high performance liquid chromatography–mass spectrometer (HPLC–MS). At last, a possible photocatalytic reaction mechanism based on such a S-scheme heterojunction (BOC/CBO) is proposed. This study provides an insight in constructing high-performance S-scheme heterojunction photocatalysts for environmental pollution remediation.