Microscopic Mechanism for Further NO Heterogeneous Reduction by Potassium-Doped Biochar: A DFT Study.

Biomass reburning is an efficient and low-cost way to control nitric oxide (NO), and the abundant potassium (K) element in biomass affects the heterogeneous reaction between NO and biochar. Due to the incomplete simulation of the NO heterogeneous reduction reaction pathway at the molecular level and the unclear catalytic effect of K element in biochar, further research is needed on the possible next reaction and the influencing mechanism of the element. After the products of the existing reaction pathways are referenced, two reasonably simplified biochar structural models are selected as the basic reactants to study the microscopic mechanism for further NO heterogeneous reduction on the biochar surface before and after doping with the K atom based on density functional theory. In studying the two further NO heterogeneous reduction reaction pathways, we find that the carbon monoxide (CO) molecule fragment protrudes from the surface of biochar models with the desorption of N2 at the TS4 transition state, and the two edge types of biochar product models obtained by simulation calculation are Klein edge and ac56 edge observed in the experiment. In studying the catalytic effect of potassium in biochar, we find that the presence of K increases the heat release of adsorption of NO molecules, reduces the energy barrier of the rate-determining step in the nitrogen (N2) generation and desorption process (by 50.88 and 69.97%), and hinders the CO molecule from desorbing from the biochar model surface. Thermodynamic and kinetic analyses also confirm its influence. The study proves that the heterogeneous reduction reaction of four NO molecules on the surface of biochar completes the whole reaction process and provides a basic theoretical basis for the emission of nitrogen oxides (NOx) during biomass reburning.

New insights into the effect of pyrolysis temperature on the spectroscopy properties of dissolved organic matter in manure-based biochar.

Dissolved organic matter (DOM) derived from biochar takes a crucial role in transport and bioavailability toward contaminants; hence, it is undeniable that a thorough analysis of its properties is important. So far, the effect of pyrolysis temperature on the functional groups, components, and evolutionary sequence of manure-based biochar DOM has not been adequately investigated. Here, DOM was released from two typical livestock manures (cow and pig) at five pyrolysis temperatures (300 ~ 700°C), and it was explored in depth with the aid of moving window 2D correlation spectroscopy (MW-2D-COS) and heterogeneous 2D correlation spectroscopy (hetero-2D-COS). The results demonstrated that the concentration, aromaticity, and hydrophobicity of DOM were greater at high temperatures, and more DOM was liberated from cow manure-based biochar at identical temperature. Protein-like compounds dominated at high temperatures. The pyrolysis temperatures of final configuration transformation points of the fulvic acid-like component and the aromatic ring C=C in DOM were 400°C and 500°C, respectively. Moreover, Fourier transform infrared spectroscopy combined with two-dimensional correlation analysis indicated that the functional group evolution of DOM depends on the pyrolysis temperature and feedstock type. The study provides a new perspective on manure management and environmental applications of biochar.

Synthesis of Acid Mine Drainage (AMD) Sludge-Derived Al-Fe3O4 as Fenton-like Catalysts for the Efficient Degradation of Tetracycline.

In recent years, the development of environmentally friendly solid catalysts derived from sludge for the efficient removal of pollutants from wastewater has triggered widespread attention. Acid mine drainage (AMD) sludge is a waste produced in the process of acid mine wastewater treatment and contains multitudes of valuable metal resources. Hence it provides the original conditions for the synthesis of metal-based Fenton catalysts. In this article, the Fenton-like catalyst Al-Fe3O4 derived from AMD sludge was first synthesized by acid leaching coprecipitation methods, and the relationship among catalyst properties and pH, growth temperature, and growth time during coprecipitation was explored. Transmission electron microscope (TEM)/vibrating sample magnetometer (VSM)/particulate size description analyzer (DLS) results showed that the Al-Fe3O4 catalyst with high purity, large particle size, and strong magnetic properties was obtained under the conditions of pH 10, reaction temperature 60 °C, and growth for 45 min. In addition, the introduction of Al active sites promoted the activation of H2O2 and improved the catalytic activity of Al-Fe3O4, and the degradation efficiency of tetracycline was up to 93.9% within 60 min, which was 1.94 times that of pure Fe3O4. Moreover, Al-Fe3O4 exhibited excellent recyclability after four adsorption-desorption cycles. Hence, this study is expected to promote the resource utilization of industrial sludge and provide a new idea for the rapid removal of TC from aqueous solution.

Effects of carboxymethyl cellulose on the emulsifying, gel and digestive properties of myofibrillar protein-soybean oil emulsion.

Improving the qualities of vegetable oil replaced animal fat meat products is particularly fascinating for the development of healthy meat products. This work was designed to investigate the effects of different carboxymethyl cellulose (CMC) concentrations (0.01 %, 0.05 %, 0.1 %, 0.2 %, and 0.5 %) on the emulsifying, gelation, and digestive properties of myofibrillar protein (MP)-soybean oil emulsions. The changes in MP emulsion characteristics, gelation properties, protein digestibility, and oil release rate were determined. Results demonstrated that CMC addition decreased the average droplet size and increased the apparent viscosity, storage modulus, and loss modulus of MP emulsions, and a 0.5 % CMC addition significantly increased the storage stability during 6 weeks. Lower CMC addition (0.01 % to 0.1 %) increased the hardness, chewiness, and gumminess of emulsion gel especially for the 0.1 % CMC addition, while higher CMC (0.5 %) content decreased the texture properties and water holding capacity of emulsion gels. The addition of CMC decreased protein digestibility during the gastric stage, and 0.01 % and 0.05 % CMC addition significantly decreased the free fatty acid release rate. In summary, the addition of CMC could improve the stability of MP emulsion and the texture properties of the emulsion gels, and decrease protein digestibility during the gastric stage.

Modified UiO-66-Br Microphotocatalyst with High Electron Mobility Enhances Tetracycline Degradation.

In this work, the Br functional group on the ligand UiO-66-Br was modified with a Bi-O bond through the secondary solvothermal method, and the synthesis method of visible light catalyst UB (UiO-66-BiOBr) with high electron mobility was explored. The findings indicate that the effective charge transfer of the functional group-modified material UB is 2.98 times and 1.22 times that of BiOBr and traditional UiO-66/BiOBr heterojunctions, respectively. Under simulated sunlight irradiation, the removal rate of tetracycline can reach 88.71%, and the photocatalytic performance is 22.73 times higher than that of UiO-66-Br. Moreover, it maintains good adsorption and photocatalytic performance under different laboratory and actual engineering water environment conditions. In the complex water environment of municipal wastewater, the degradation effect reaches more than 80%. Finally, the decomposition pathways of TC and ecotoxicities of the intermediates were analyzed via combining theoretical calculation, LC-MS/MS, and T.E.S.T.

Study on the cadmium and copper binding characteristics of dissolved organic matter released from human-feces-biochar (HFDOM) using parallel factor analysis (PARAFAC) and two-dimensional correlation spectroscopy (2D-COS).

The benefits of applying manure directly compared to carbonized applications are controversial, and the impact of dissolved organic matter (DOM) released from human feces-based biochar (HFDOM) on the soil environment is not yet known. Comparing the properties of the HFDOM at different pyrolysis temperatures and its binding properties to heavy metals (HMs) can provide some valuable information for the application of human manure-based biochar for soil amendment or HM remediation in soils. The result of EEM-PARAFAC shows that HFDOM contains four components. A comparison of the maximum fluorescence intensity of HFDOM bound to HMs at different pyrolysis temperatures indicates that high pyrolysis temperatures reduce the amount of HFDOM. Upon comparative analysis of 2D-SFS-COS maps, cadmium (Cd(II)) preferentially binds to humic substances and fulvic-like substances at different pyrolysis temperatures (280 °C, 380 °C), respectively, while copper (Cu(II)) preferentially complexes with fulvic-like substances in both cases. The 2D-FTIR-COS graphs with different pyrolysis temperatures (280 °C, 380 °C) are observed, and Cd(II) binds preferentially to the C-H stretching (peak 3030 cm-1) of olefins, the C-O stretching vibration, and the O-H bending vibration (peak 1231 cm-1) of carboxyl groups, respectively, while Cu(II) binds predominantly to the C-O stretching of alcohols, ethers, and esters (peak 1084 cm-1), the C = O stretch of the carboxylic acid (peak 1590 cm-1), respectively. The variability of these findings suggests that the pyrolysis temperature exerts a significant influence on the functional groups in HFDOM. Furthermore, the complexation stability constant between Cu(II) and the components decreases as the pyrolysis temperature increases, probably because the pyrolysis temperature changes the content of HFDOM and the distribution of functional groups, but the assessment of the influence still needs to be further investigated.

Enhanced photocatalytic activity by regulating charge transferring: Unveiling the decisive role of cerium oxide crystal-facet engineering over heterojunction.

Heterojunctions have been verified to be effective for separation of photogenerated electrons and holes, therefore improving the photocatalytic efficiency. Meanwhile, cerium oxide (CeO2) is an ideal semiconductor for studying the influence of different exposed crystal facets on regulation of electron transport pathways over heterojunctions. Herein, various kinds of crystal facet-dependent CeO2/g-C3N4 (graphitic carbon nitride) heterojunctions have been successfully engineered as representative model catalysts, and their critical role in regulating charge transfer pathways has been confirmed by systemic characterizations. It was found that facet-dependent heterojunctions followed different charge transport pathways, leading to different H2 evolution activities. In detail, heterojunctions with (100) and (110) exposed surfaces followed the Z-scheme transport pathways, while heterojunction with (111) exposed surface followed the type-II pathway. The H2 evolution rates via these three kinds of heterojunctions were determined to be 3.084, 1.925, and 1.128 mmol·g-1·h-1, respectively, which were 13.3, 7.9, 4.2 times that of bare g-C3N4. It's revealed that the different exposed crystal facets of CeO2 with different Fermi levels determine the transport pathways of photogenerated carriers. This work shows an example of controlling photocatalytic activity by facet-dependent heterojunctions and reveals the importance role of crystal-facet engineering toward heterojunction construction, which is expected to provide an important guidance for the design of new photocatalytic systems.

Binding characteristics of Pb and Zn to low-temperature feces-based biochar-derived DOM revealed by EEM-PARAFAC combined with general and moving-window two-dimensional correlation analyses.

Pyrolysis carbonization of human feces has shown potential for converting feces biomass into a soil amendment. However, little is known about the interactions of DOM derived from feces-based biochar produced at low-temperature with heavy metals (HMs). In this study, the binding properties of Pb(II) and Zn(II) with DOM derived from feces-based biochar produced at low pyrolysis temperatures were investigated using EEM-PARAFAC combined with general, and moving-window two-dimensional correlation analyses (2D-COS). The results revealed that DOM from biochar produced at 280 °C exhibited a higher Pb(II) and Zn(II) affinity and more binding sites than DOM produced at 380 °C. The fulvic-like and humic-like components exhibited obvious fluorescence quenching after the heavy metal addition, and the complexes formed with Pb(II) and Zn(II) were more stable. C-H groups exhibited the fastest response to Pb(II) and Zn(II) binding in the FB280 DOM, while the COO- groups of carboxylic acids in the FB380 DOM exhibited the fastest response to Pb(II) and Zn(II). Moreover, the mutation concentration range of components and functional groups in DOM, as analyzed by MW2D-COS, was greater for Zn(II) than for Pb(II). These results provide a more detailed molecular-level understanding of the interaction mechanisms between heavy metals and feces-based biochar-derived DOM and the effect of HM concentration on DOM binding. Further, these results will help to provide a reasonable reference for feces management and feces-based biochar in controlling soil HMs.

A new genus, Duffelsa gen. n., with descriptions of three new species and one new combination (Hemiptera: Cicadidae).

One new cicada genus, Duffelsa gen. n., is erected in the tribe Leptopsaltriini Moulton, 1923, with the designation of Pomponia orientalis (Distant, 1912) as the type species. Three new species, D. parvula sp. n., D. grandia sp. n. and D. rubida sp. n., are described from China. A key to species of Duffelsa gen. n. is provided. The relationship of this new genus to related taxa is discussed.

Rhodium(III)-catalyzed oxidative annulation of isoquinolones with allyl alcohols: synthesis of isoindolo[2,1-b]isoquinolin-5(7H)-ones.

An efficient rhodium(III)-catalyzed direct C-H oxidative annulation of isoquinolones with allyl alcohols as C1 synthons has been successfully developed. This protocol enables the straightforward synthesis of structurally diverse isoindolo[2,1-b]isoquinolin-5(7H)-ones with high atom economy, tolerates a broad spectrum of functionalities, and is applicable to one-pot operation from readily available N-methoxybenzamides.

Prediction of chemical reproductive toxicity to aquatic species using a machine learning model: An application in an ecological risk assessment of the Yangtze River, China.

The endocrine disrupting chemicals (EDCs) have been at the forefront of environmental issues for over 20 years and are a principle factor considered in every ecological risk assessment, but this kind of risk assessment faces difficulties. The expense, time cost of in vivo tests, and lack of toxicity data are key limiting factors for the ability to conduct ecological risk assessments of EDCs to aquatic species. In this study, a machine learning model named the support vector machine (SVM) was used to predict the reproductive toxicity of EDCs, and the performance of the models was evaluated. The results showed that the SVM model provided more accurate toxicity prediction data compared with the interspecies correlation estimation (ICE) model developed by previous study to predict the reproductive toxicity. The application of the predicted toxicity data was an important supplement to the observed data for the ecological risk assessment of EDCs in the Yangtze River, where estrogens and phenolic compounds have been found at some sampling sites in the middle and lower reaches. The results showed that the ecological risk of estrone, 17ß-estradiol, and ethinyl estradiol were significant. This study revealed the application potential of machine learning models for the prediction of reproductive toxicity effects of EDCs. This can provide reliable alternative toxicity data for the ecological risk assessments of EDCs.

Rhodium(III)-Catalyzed Oxidative Cyclization of Oxazolines with Cyclopropanols: Synthesis of Isoindolinones.

The synthesis of C3-substituted isoindolin-1-ones from oxazolines and cyclopropanols has been achieved with oxazoline as a bifunctional nucleophilic directing group. The reaction proceeds by the cleavage of three chemical bonds and allows the formation of three new chemical bonds, a C-N bond, a C-C bond, and a C-O bond, in a single step.

Correction: Rhodium(iii)-catalyzed oxidative alkylation of N-aryl-7-azaindoles with cyclopropanols.

Correction for 'Rhodium(iii)-catalyzed oxidative alkylation of N-aryl-7-azaindoles with cyclopropanols' by Jidan Liu et al., Org. Biomol. Chem., 2021, DOI: .

Rhodium(III)-catalyzed oxidative alkylation of N-aryl-7-azaindoles with cyclopropanols.

An efficient Rh(iii)-catalyzed C-H oxidative alkylation of N-aryl-7-azaindoles with cyclopropanols by merging tandem C-H and C-C cleavage was developed. This transformation features mild reaction conditions, high regioselectivity, and excellent functional group compatibility. The resulting ß-aryl ketone derivatives can be readily transformed into 7-azaindole-containing π-extended polycyclic heteroarenes.

Copper-mediated tandem ring-opening/cyclization reactions of cyclopropanols with aryldiazonium salts: synthesis of N-arylpyrazoles.

A general method for the synthesis of structurally diverse N-arylpyrazoles from readily available cyclopropanols and aryldiazonium salts is disclosed. The reaction was conducted at room temperature within minutes with a broad substrate scope and excellent regioselectivity.

Mesoporous bimetallic Fe/Co as highly active heterogeneous Fenton catalyst for the degradation of tetracycline hydrochlorides.

Mesoporous bimetallic Fe/Co was prepared as a Fenton-like catalyst to degrade the tetracycline hydrochlorides (TC). The nanocasting strategy with KIT-6 as a hard template was carried out to synthesize the mesoporous bimetallic catalyst. The mesoporous bimetallic Fe/Co catalyst was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption-desorption isotherms, and Brunauer-Emmett-Teller (BET) method. The results showed that the catalyst has significant nanofeatures; the surface area, pore size, and particle size were 113.8 m2g-1, 4 nm, and 10 nm, respectively. In addition, the effects of the operating parameters, such as the iron-to-cobalt ratio, pH, H2O2, and initial TC concentrations on its catalytic performance were investigated. The best operating parameters were as follows: iron-to-cobalt ratio = 2:1 to 1:1, pH = 5-9, H2O2: 30 mmol, initial TC less than 30 mg/L. Furthermore, the mesoporous bimetallic Fe/Co showed a good performance for degrading TC, achieving a removal rate of 86% of TC after 3 h under the reaction conditions of H2O2 = 30 mmol, mesoporous bimetallic Fe/Co = 0.6 g/L, TC = 30 mg/L, pH = 7.0, and temperature = 25.5 °C. The mesoporous bimetallic Fe/Co catalyst shows good stability and reusability. This work demonstrated that mesoporous bimetallic Fe/Co has excellent catalytic efficiency, smaller amounts of leached ions, and wider pH range, which enhance its potential applications.

Detection of dissolved organic matter in saline-alkali soils using synchronous fluorescence spectroscopy and principal component analysis.

Dissolved organic matter (DOM) is attributed a key role in soil major biogeochemical processes. Its molecular characteristics can reflect both its source and its biogeochemical history. Saline-alkali soil samples were collected from a field in desert and semi-desert region. DOM was analyzed by synchronous fluorescence spectroscopy. Principal Components Analysis (PCA) of synchronous fluorescence spectra was used to detect and describe changes in the DOM in different soil profiles. The analysis of PCA yielded 2 PCs that account for 97% of the variance. DOM is characterized by a dominant tyrosine-like fluorophore in the Region I (PC1>0.9, PC2<0.3), including soils Ke02, Ke03, Ke04, Rh02, Rh03, Rh04, Sa04 and Sc04. The region II including Kf02, Sa01, Yb01, Yzd01 and Yzd02 obtain higher PC2 (>0.9) and lower PC1 (<0.3) loading, which is dominated humic-like fluorophore. Hierarchical cluster analysis (HCA) identified five main clusters. The results of hierarchical cluster analysis (HCA) were consistent with the PCA. The ratio of fluorescence intensity of humic substances at long wavelengths and short wavelengths was used to indicate the humification of organic matter. Two ratios (I(345/318) and I(362/318).) can be used to indicate the humification of DOM. The humification degree of the remaining soils has no systematic trend because of land use, agricultural irrigation, soil erosion and salinization. Soils obtained a relatively high humification degree in the region II and a relatively low humification degree in the region I.

[Denitrification on secondary effluent of acrylic fiber wastewater by tri-stage biofilm advanced reactor].

To resolve the shortage of carbon source during traditional denitrification used to treat secondary effluent of acrylic fiber wastewater, tri-stage biofilm reactor was used, the influence of pH of influent, HRT, and NH4(+) -N concentration in raw water on NH4(+) -N removal was investigated. Efficiency of TN removal was also investigated. It demonstrated that the optimal HRT and pH were 24 hours and 7.8-8.0 respectively. Under these conditions the removal efficiencies of NH4(+) -N and TN were 94. 6% and 53% respectively. And the removal efficiency of NH4(+) -N had no relationship with the concentration of the inflow water. With absence of organic carbon source in the reactor, efficiency of TN removal was obvious, the average and the highest removal efficiencies of TN were 53% and 66% respectively, efficiency of secondary effluent of acrylic fiber wastewater nitrogen removal was obvious when treated with Tri-stage biofilm reactor.

Spectroscopic techniques for quantitative characterization of Cu (II) and Hg (II) complexation by dissolved organic matter from lake sediment in arid and semi-arid region.

Dissolved organic matter (DOM) was extracted from six sediment samples in arid and semi-arid region, which was characterized by fluorescence excitation-emission matrices (EEMs). The results showed that four fluorescent peak, fulvic-like (peak A), humic-like (peak C) and two tryptophan-like (peaks B and D), were identified in lake sediment DOM. Fluorescence quenching titration showed that peaks B and D were quenched gradually by adding additional Cu (II) and Hg (II), whereas humic-like substances had no systematic trend of the change of fluorescence intensity. Increasing fluorescence intensity value of humic-like substances can also be found. The modified Stern-Volmer model was used to calculate conditional stability constants (logK) and the percent of fluorophores (f %) which participate in the complexation between DOM and Cu (II), and Hg (II). The results showed that DOM-Cu (II) and DOM-Hg (II) complexes had higher logK values of 4.21-5.23 and the logK values of DOM-Cu (II) are much larger than the corresponding values for Hg (II). Peak B showed relatively low logK and high f % values than those of peak D. Different pollution sources which are mainly obtained from the upstream industrial wastewater, domestic sewage and return water of farmland irrigation tend to affect the stability constants and complexing capacities of Cu (II) and Hg (II).

Study on the spectral and Cu (II) binding characteristics of DOM leached from soils and lake sediments in the Hetao region.

INTRODUCTION: Dissolved organic matter (DOM) is the most active component in environmental system and its chemical and structural characteristics most likely influence its biodegradation. Four surface soil (0-20 cm) and three core sediment samples (0-10 cm) were collected from Wuliangsuhai Lake. The objectives of this study were to investigate the spectral properties and humification degree of DOM and to determine and discuss comparatively the complexing capacities and stability constants of DOM by Cu (II) in the Hetao region. MATERIALS AND METHODS: In this study, fluorescence spectra and fluorescence quenching methods were used to evaluate the humification degree of DOM and calculate the complexing capacities and the stability constants between DOM and Cu (II). RESULTS AND DISCUSSION: Two defined peaks, at wavelengths of 260∼300 nm (peak I) and 300∼350 nm (peak II), could be identified for soil DOM at a Δλ value of 30 nm. In sediment DOM extracts, a third peak (III) was observed near 364 nm. The results show that there is a significant difference in the structure of DOM because of different sources. The humification degree is significantly higher for soil samples than those of sediment samples. The FT-IR spectra of DOM show that structure in sediment DOM is more functional groups than those in soil DOM. DOM has a stronger Cu binding affinity in soils than in sediment in the Hetao region, which may lead to potentially significant influence on the migration and transformation of Cu (II).