Three-dimensional Fluorescence Research Articles

A novel 3D-fluorescence sensing strategy based on HN-chitosan polymer probe for rapid identification and quantification of potential adulteration in saffron.

Saffron is a candidate for various kinds of fraud to make huge profits. The present study proposed an efficient three-dimensional (3D) fluorescence sensing strategy based on hydrophilic hydrazine-naphthalimide functionalized chitosan (HN-chitosan) polymer probe for rapid identification and quantification of potential adulteration in saffron. The amino functional group in the HN-chitosan probe reacted specifically with the Oxygen-containing group of active ingredients in saffron, amplifying the signal difference between saffron and the adulterants, which was comprehensively characterized by 3D fluorescence. Four advanced chemometrics methods were applied for the classification of saffron and adulterated saffron, and good performance were obtained in both training and prediction sets. Furthermore, the PLS regression model was applied to the prediction of adulteration level in saffron and showed satisfactory accuracy. This strategy provides a new solution for rapid identification and quantification of potential adulteration in saffron, which contributes to the healthy development of its industry.

Mixed pesticide recognition based on three-dimensional fluorescence spectroscopy and a convolutional neural network.

Kasugamycin, spinosad, and lambda-cyhalothrin are common organic pesticides that are widely used to control and prevent diseases and pests in fruits and vegetables. However, the unreasonable use of pesticides will cause great harm to the natural environment and human health. Pesticides often exist in the form of mixtures in nature. Establishing recognition models for mixed pesticides in large-scale sample testing can provide guidance for further precise analysis and reduce resource waste and time. Therefore, finding a fast and effective identification method for mixed pesticides is of great significance. This paper applies three-dimensional fluorescence spectroscopy to detect mixed pesticides and introduces a convolutional neural network (CNN) model structure based on an improved LeNet-5 to classify mixed pesticides. The input part of the model corresponds to fluorescence spectrum data at excitation wavelengths of 250-306nm and emission wavelengths of 300-450nm, and the mixed pesticides are divided into three categories. The research results show that when the learning rate is set to 1 and the number of iterations is 300, the CNN classification model has ideal performance (with a recognition accuracy of 100%) and is superior to the performance of the support vector machine method. This paper provides a certain methodological basis for the rapid identification of mixed pesticides.

Characteristics of Microplastic-derived Dissolved Organic Matter(MPDOM) and the Complexation Between MPDOM and Sulfadiazine/Cu2

Microplastic-derived dissolved organic matter(MPDOM) during the aging process could be complexed with organic pollutants, heavy metals, and other contaminants and thus affect their migration and transformation. In this study, two types of microplastics, polyethylene terephthalate(PET) and polystyrene(PS), were selected to investigate the spectral properties of MPDOM and their effect on the complexation between MPDOM and sulfadiazine(SDZ)/copper ion(Cu2+) using the fluorescence quenching method, various spectroscopic analysis techniques, and the Ryan-Weber quenching model. The results of UV-vis absorption spectroscopy analysis showed that the molecular weight of the two MPDOMs decreased; the aromaticity and humification increased; and the carboxyl, carbonyl, hydroxyl, and ester substituents on aromatic rings increased after aging. The fluorescence quenching process between MPDOM and SDZ/Cu2+ was static quenching. After quenching, the aromaticity and humification of the two MPDOMs were similar, and the molecular weights were comparable. Combined with three-dimensional fluorescence spectra and parallel factor analysis, two humic-like components and one protein-like component were identified. In addition, the protein-like components of MPDOM reacted preferentially with SDZ and were more sensitive to Cu2+. The results of the Ryan-Weber quenching model revealed that the binding ability of humic-like components to PET-DOM was higher in both SDZ and Cu2+ quenching systems, but the binding ability of MPDOM in the SDZ quenching system was generally stronger than that in the Cu2+ system.

Insight into the application of micro-nano bubbles combined with heat-activated persulfate oxidation for removing dissolved organic matter from printing and dying wastewater

The effluent quality of printing and dyeing wastewater after secondary treatment does not meet industry discharge standards, which poses serious environmental risks. In this work, micro-nano bubbles and a heat-activated persulfate advanced oxidation process were innovatively combined to thoroughly treat industrial printing and dyeing wastewater. Under the optimal reaction conditions (a reaction time of 60 min, persulfate concentration of 20 mM, and temperature of 40 °C), the effluent quality met the discharge standards. Furthermore, the degradation and transformation mechanisms of dissolved organic matter during the wastewater treatment process were investigated by three-dimensional fluorescence spectroscopy and Fourier ion transform spin resonance mass spectrometry. The results showed that organic compounds in the wastewater were clearly degraded by the treatment process, and this was accompanied by a significant increase in molecular diversity. In summary, this work provides insight into the practical application of micro-nano bubbles in the advanced oxidation treatment of industrial wastewater as well as the degradation mechanism responsible for removing pollutants from this wastewater.

Synthesis, biological evaluation and action mechanism of 7H-[1,2,4] triazolo [3,4-b] [1,3,4] thiadiazine-phenylhydrazone derivatives as α-glucosidase inhibitors

In our work, several 7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine-phenylhydrazone derivatives as α-glucosidase inhibitors (α-GIs) were synthesized and characterized by 1H NMR, 13C NMR, and HRMS spectrum. Then, their bio-activity against the α-glucosidase (α-Glu) was further evaluated. Among them, almost all compounds displayed better bio-activity with IC50 from 31.23 ± 0.89 to 213.50 ± 4.19 μM than acarbose (IC50 = 700.20 ± 10.55 μM). In particular, compound 5o showed the best potency to inhibit α-Glu in a mixed manner. Moreover, the action mechanisms of 5o were further clarified including fluorescence quenching, circular dichroism spectra, three-dimensional fluorescence spectra, molecular docking, etc. All mechanism studies revealed that 5o could arouse the changed secondary structure of α-Glu to hinder enzyme catalytic activity. It was observed from an in vivo study that 5o of 20 mg/kg could significantly decrease by 24.45 % postprandial blood glucose in mice vs. the control. Meanwhile, 5o had low drug-drug interaction potential and was likely to be an orally active compound. Moreover, 5o was observed to be no obvious cytotoxicity to HEK-293 cells. In summary, compound 5o exhibited one potential to be further applied as an antidiabetic drug.

Enhancing anaerobic digestion of waste activated sludge by dielectric barrier discharge pretreatment: Nutrient release, sludge hydrolysis and microbial community succession

A dielectric barrier discharge (DBD) pretreatment of waste activated sludge (WAS) was developed for boosting the releasing of organic matter from floc structures and microbial cells. The changes of protein and polysaccharide in different extracellular polymeric substances layers of SCOD releasing from sludge were determined by using three-dimensional fluorescence spectra. Significantly improved cumulative methane production was achieved via enhancing anaerobic digestion, which was 83.5% higher than that of the control. The formed ∙OH radicals play a key role in sludge hydrolysis, thus improving the biodegradability of WAS. Furthermore, high-throughput sequencing analysis showed that DBD pretreatment improved the relative abundances of the main functional microbes with respect to sludge hydrolysis and anaerobic digestion. Therefore, this study verifies the feasibility of DBD pretreatment in sludge hydrolysis and is expected to provide a practical new technology for anaerobic digestion of WAS.

Preparation of Ti4O7 Reactive Electrochemical Membrane for Electrochemical Oxidation of Coking Wastewater

The effluent of coking wastewater comprises hundreds of refractory organics and is characterized by high toxicity and non-biodegradation. Electrochemical advanced oxidation processes (EAOPs) have been widely applied in the field of water purification. In this study, a Ti4O7 reactive electrochemical membrane (REM) was prepared using the plasma spraying method for the electro-oxidation of coking wastewater. The composition and surface morphology of the Ti4O7 REM were characterized via X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The computational fluid dynamics (CFD) simulation was used to compare the mass transfer performance of the Ti4O7 REM in traditional batch (TB) mode and flow-through (FT) mode. In the FT mode, the effects of current density and anode–cathode distance on the treatment efficiency were investigated, and the electrocatalytic performance of the anode on coking wastewater was analyzed. The results showed that the COD removal efficiency reached 76.2% with an energy consumption of 110.5 kWh kg−1 COD under the optimal condition. In addition, cathodic polarization provides an effective technique for maintaining the long-term activity of the Ti4O7 REM. The three-dimensional fluorescence results and UV-vis spectrum showed that the aromatic compounds could be effectively degraded using the Ti4O7 REM. The Ti4O7 REM demonstrated excellent performance of electrochemical oxidation and satisfactory stability, which had a strong potential for application in the field of practical wastewater and engineering practices that respond to the concept of sustainable development.

A young researcher’s guide to three-dimensional fluorescence microscopy of living cells

Three-dimensional imaging of fast intracellular processes by fluorescence microscopy should provide decent spatial and high temporal resolution while minimizing fluorophore bleaching and cytotoxicity. We give a condensed introductory overview of three contemporary methods mostly used for imaging of living cells in 3D and compare their performance in terms of temporal and spatial resolution, imaging flexibility and specimen photodamage: point-scanning confocal microscopy, spinning-disc confocal microscopy, and lattice light-sheet microscopy. While point-scanning instruments are unsurpassed in terms of confocal performance, flexibility and configurability of their optical path, spinning-disc and lattice light-sheet optical designs excel in acquisition speed and low levels of light-inflicted specimen deterioration.

Enhanced synaptic protein visualization by multicolor super-resolution expansion microscopy.

Understanding the organization of biomolecules into complexes and their dynamics is crucial for comprehending cellular functions and dysfunctions, particularly in neuronal networks connected by synapses. In the last two decades, various powerful super-resolution (SR) microscopy techniques have been developed that produced stunning images of synapses and their molecular organization. However, current SR microscopy methods do not permit multicolor fluorescence imaging with 20 to 30nm spatial resolution. We developed a method that enables 4-color fluorescence imaging of synaptic proteins in neurons with 20 to 30nm lateral resolution. We used post-expansion immunolabeling of eightfold expanded hippocampal neurons in combination with Airyscan and structured illumination microscopy (SIM). We demonstrate that post-expansion immunolabeling of approximately eightfold expanded hippocampal neurons enables efficient labeling of synaptic proteins in crowded compartments with minimal linkage error and enables in combination with Airyscan and SIM four-color three-dimensional fluorescence imaging with 20 to 30nm lateral resolution. Using immunolabeling of Synaptobrevin 2 as an efficient marker of the vesicle pool allowed us to identify individual synaptic vesicles colocalized with Rab3-interacting molecule 1 and 2 (RIM1/2), a marker of pre-synaptic fusion sites. Our optimized expansion microscopy approach improves the visualization and location of pre- and post-synaptic proteins and can thus provide invaluable insights into the spatial organization of proteins at synapses.

Microbial induced calcium precipitation by Zobellella denitrificans sp. LX16 to simultaneously remove ammonia nitrogen, calcium, and chemical oxygen demand in reverse osmosis concentrates

In recent years, with the rapid development of industrial revolution and urbanization, the generation and treatment of a large number of salt-containing industrial wastewater has attracted wide attention. A novel salt-tolerant Zobellella denitrificans sp. LX16 with excellent nitrogen removal and biomineralization capabilities was isolated in this experiment. Kinetic experiments were conducted to determine the optimal condition. Under this condition, chemical oxygen demand (COD) can be entirely removed together with ammonia nitrogen, and the removal efficiency of calcium was 88.09%. Growth curves and nitrogen balance tests showed that strain LX16 not only had good HNAD and MICP capabilities, but also had high nitrite reductase and nitrate reductase activities during this process. Three-dimensional fluorescence results reflected that when external carbon sources were lacking or salinity was high, humic acid could effectively enhance the metabolic activity of heterotrophic nitrifying aerobic denitrifying microorganisms through extracellular electron transfer, and the substances produced in the metabolic process could promote biommineralization. Moreover, combined with SEM, SEM-EDS, XRD and FTIR analysis, it is concluded that the microbial surface can provide nucleation sites to form calcium salts, and with the increase of alkalinity to generate Ca5(PO4)3OH. The theoretical basis for the use of biological treatment in reverse osmosis wastewater have been proved by this experiment.

Interactions between gold nanoparticles with different morphologies and human serum albumin

Introduction: Three different shapes of gold nanoparticles were synthesized in this experiment. At the same time, studies compared their effects with human serum albumin (HSA).Methods: Gold nanoparticles (AuNPs) with three different morphologies, such as, nanospheres (AuNSs), nanorods (AuNRs), and nanoflowers (AuNFs) were synthesized via a seeding method and their characteristic absorption peaks were detected using ultraviolet-visible (UV-vis) absorption spectroscopy, Telectron microscopy (TEM), Dynamic Light Scattering (DLS) and Zeta potential measurements, circular dichroism (CD), and Fourier transform infrared spectroscopy (FTIR) to study the interactions between them and HSA. By comparing the thermodynamic parameters and quenching mechanism of the three materials, similarities and differences were determined in their interactions with HSA.Results: The results showed that with an increase in the concentration of the AuNPs with the three different morphologies, the UV-vis absorption peak intensity of the mixed solution increased, but its fluorescence intensity was quenched. This indicates that the three types of AuNPs interact with HSA, and that the interactions between them represent a static quenching process, which is consistent with the conclusions derived from three-dimensional fluorescence experiments. Through variable-temperature fluorescence experiments, the binding constants, number of binding sites, and thermodynamic parameters of the interactions between the three types of AuNPs and HSA were determined. The Gibbs free energy changes were <0, indicating that the reactions of the three types of AuNPs with HSA are spontaneous, resulting in associated matter. Binding constant measurements indicated that the strongest binding took place between the AuNFs and HSA. In addition, the results of fluorescence, CD spectroscopy, and FTIR showed that three different shapes of AuNPs can induce conformational changes in HSA and reduce the α-helix content. Among them, AuNFs have the smallest ability to induce conformational changes.Discussion: According to studies, AuNFs interact more favorably with HSA. This can be used as a reference for the administration of drugs containing AuNPs.

A novel strategy of peracetic acid activation by dielectric barrier discharge plasma for bisphenol a degradation: Feasibility, mechanism and active species dominant to degradation pathway

As a typical endocrine disruptor, bisphenol A (BPA) can not only affect the reproduction and development of aquatic organisms, but also pose a significant threat to environmental safety and human health. This work proposed a novel strategy of peracetic acid (PAA) activation by dielectric barrier discharge (DBD) plasma for BPA degradation. It can be confirmed that DBD plasma can effectively activate PAA. 93.4 % BPA was destructed in the DBD/PAA system, which was 39.8 % higher than that in the DBD system alone. The energy yield (G50) of the DBD/PAA system was 211.5 g/kWh, while the single DBD system was only 59.7 g/kWh. The degradation efficiencies of chemical oxygen demand (COD) and total organic carbon (TOC) were also improved. The active substances such as OH, CH3C(O)OO, 1O2, O2−, and e− were important for the degradation of BPA in the DBD/PAA system. The pH dropped, and the total conductivity rose in the degradation processing of BPA. Three-dimensional fluorescence spectroscopy, liquid chromatography mass spectrometry (LC-MS) and density functional theory (DFT) simulation were adopted to investigate the degradation mechanism and process. The toxicity of intermediates in three degradation pathways to aquatic organisms was reduced. The degradation efficiency of BPA was more effective as input power increased and initial concentration decreased. BPA was more easily degraded under acidic solutions than under alkaline and neutral solutions. In addition, the effects of typical inorganic ions and humic acids on BPA degradation in the DBD/PAA system were examined. Finally, the DBD/PAA system is suitable for the application of various pollutants and actual wastewater. This research proposes an innovative idea and reference for PAA activation and plasma application in wastewater treatment.

The influence of micro-flocculation on membrane fouling during ultrafiltration of dissolved organic matter

This study investigated the mitigating effect of micro-flocculation as an ultrafiltration (UF) membrane pretreatment process on membrane fouling caused by organic matter in urban micro-polluted river water. The removal characteristics of organic matter by micro-flocculation were analyzed using three-dimensional fluorescence excitation emission matrix (3D-FEEM) and liquid chromatography organic carbon detector (LC-OCD). Furthermore, the variation of floc properties such as flocculation index and fractal dimension of micro-flocs formed under different flocculant dosages and their effects on UF membrane flux were investigated. The experimental results show that micro-flocculation using ferric chloride (FeCl3) can effectively remove large molecular weight organics. The features of flocs, which are influenced by the amount of FeCl3, affect the formation of the cake layer. Micro-flocculation can control the formation of a floc cake layer with a larger size and lower fractal dimension. It is helpful to effectively delay the attenuation rate of membrane flux by reducing membrane pore blockage and forming a filter cake layer with high porosity, which is of great significance for improving membrane technology. After the FeCl3 micro-flocculation treatment, the final specific flux of the membrane increased by 57.0 %. The combination of FeCl3 micro-flocculation and UF is a superior technical and economical treatment scheme for micro-polluted river water.

Effect of lysozyme combined with hydrothermal pretreatment on excess sludge and anaerobic digestion

Anaerobic digestion (AD) is widely employed for sludge stabilization and waste reduction. However, the slow hydrolysis process hinders methane production and leads to prolonged sludge issues. In this study, an efficient and eco-friendly lysozyme pre-treatment method was utilized to address these challenges. By optimizing lysozyme dosage, hydrolysis and cell lysis were maximized. Furthermore, lysozyme combined with hydrothermal pretreatment enhanced overall efficiency. Results indicate that: (1) When lysozyme dosage reached 90 mg/g TS after 240 min of pretreatment, SCOD, soluble polysaccharides, and protein content reached their maxima at 855.00, 44.09, and 204.86 mg/L, respectively. This represented an increase of 85.87%, 365.58%, and 259.21% compared to the untreated sludge. Three-dimensional fluorescence spectroscopy revealed the highest fluorescence intensity in the IV region (soluble microbial product), promoting microbial metabolic activity. (2) Lysozyme combined with hydrothermal pretreatment significantly increased SCOD, soluble proteins, and polysaccharide release from sludge, reducing SCOD release time. Orthogonal experiments identified Group 3 as the most effective for SCOD and soluble polysaccharide release, while Group 9 released the most soluble proteins. The significance order of factors influencing SCOD, soluble proteins, and polysaccharide release is hydrothermal temperature > hydrothermal time > enzymatic digestion time.(3) The lysozyme-assisted hydrothermal pretreatment group exhibited the fastest release and the highest SCOD concentration of 8,135.00 mg/L during anaerobic digestion. Maximum SCOD consumption and cumulative gas production increased by 95.89% and 130.58%, respectively, compared to the control group, allowing gas production to conclude 3 days earlier.

Unveiling the molecular responses of dissolved organic matter in landfill leachate to activated carbon adsorption

Powdered activated carbon (PAC) is an effective method for removing dissolved organic matter (DOM) in membrane bioreactor effluent of landfill leachate (MBR effluent). Among commercially available PACs, wood-based PAC (WoAC) and coal-based PAC (CoAC) are two most common ones. However, the interactions between two PACs and DOM in MBR effluent at the molecular level as well as the effect of PACs properties on the adsorption of DOM compounds are not fully understood. To address the gap, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), three-dimensional fluorescence excitation-emission matrix (EEM) spectroscopy and other spectroscopic techniques were employed to study the change of DOM in MBR effluent when adsorbed by WoAC and CoAC. The results showed that CoAC had a better removal performance of DOM (89.2% for UV254 and 78.4% for DOC) than WoAC (80.9% for UV254 and 70.8% for DOC), which was likely due to the Fe component in CoAC playing an important role in the DOM adsorption process. Both WoAC and CoAC exhibited preferential adsorption for compounds with high unsaturation or poor oxygen. Moreover, the Fe component in CoAC may bind with some functional groups (e.g., carboxyl groups) in unsaturated compounds, which may enhance the adsorption of unsaturated compounds. These findings deepen our understanding of PAC-DOM interactions at the molecular level and provide guidance for designing cost-effective PACs for landfill leachate treatment.

Direct and Indirect Effects of Land Use on Dissolved Organic Matter in a Typical Karst River

Land use can directly affect the abundance of riverine dissolved organic matter (DOM) by transporting terrestrial organic matter to rivers and can also indirectly enhance local production of DOM by increasing riverine nutrient loading. This study investigated the characteristics and spatial distribution of DOM components in the Furong River during the rainy season (July) using ultraviolet-visible light absorption spectroscopy (UV-VIS) and three-dimensional excitation emission matrix fluorescence spectroscopy-parallel factor analysis (EEM-PARAFAC) techniques. Furthermore, correlation analysis and the partial least squares path model (PLS-PM) were used to identify and quantify the direct and indirect impacts of land use on DOM at multiple scales. The results revealed that:① the direct effects of land use on DOM were generally stronger than the indirect effects. ② The responses of different DOM components to riverine nutrient status and land use varied, with dissolved organic carbon (DOC) and colored dissolved organic matter (CDOM) components being more susceptible to riverine nutrient status and fluorescent dissolved organic matter (FDOM) being more sensitive to land use. ③ The direct impact intensity of land use on DOC and CDOM fluctuated slightly with the spatial scale, but the total impact intensity had no visible spatial scale difference, and the direct impact intensity on the FDOM component decreased with the increase in spatial scale. ④ Dryland, urban and other construction land, patch density (PD), edge density (ED), and Shannon's diversity index (SHDI) were typical land use metrics that exacerbated DOM abundance, whereas paddy field, shrubland, largest patch index (LPI), and aggregation index (AI) were typical land use metrics that effectively mitigated DOM abundance. Total nitrogen (TN), nitrate nitrogen (NO3--N), and dissolved total phosphorus (DTP) were water quality parameters that were significantly affected by land use and were closely related to DOM components, that is, nitrogen and phosphorus played an important "intermediary" role in "land use-riverine DOM." FDOM could be used as indicators to measure the strength of terrestrial organic matter directly input to rivers by land use.

Noninvasive detection of diabetes mellitus based on skin fluorescence and diffuse reflectance spectroscopy.

There is an urgent need for a mass population screening tool for diabetes. Skin tissue contains a large number of endogenous fluorophores and physiological parameter markers related to diabetes. We built an excitation-emission spectrum measurement system with the excited light sources of 365, 395, 415, 430, and 455 nm to extract skin characteristics. The modeling experiment was carried out to design and verify the accuracy of the recovery of tissue intrinsic discrete three-dimensional fluorescence spectrum. Blood oxygen modeling experiment results indicated the accuracy of the physiological parameter extraction algorithm based on the diffuse reflectance spectrum. A community population cohort study was carried out. The tissue-reduced scattering coefficient and scattering power of the diabetes were significantly higher than normal control groups. The Gaussian multi-peak fitting was performed on each excitation-emission spectrum of the subject. A total of 63 fluorescence features containing information such as Gaussian spectral curve intensity, central wavelength position, and variance were obtained from each person. Logistic regression was used to construct the diabetes screening model. The results showed that the area under the receiver operating characteristic curve of the model for predicting diabetes was 0.816, indicating a high diagnostic value. As a rapid and non-invasive detection method, it is expected to have high clinical value.

A rapid and low-cost method for detection of nine kinds of vegetable oil adulteration based on 3-D fluorescence spectroscopy

The integrity of vegetable oil has become a focal concern within the global food industry, particularly in specific regions where economic interests drive authenticity issues. In this study, we used three-dimensional (3-D) fluorescence spectroscopy for the qualitative and quantitative analysis of adulteration in different vegetable oils, offering the advantages of rapid and low-cost detection. Nine types of adulterated vegetable oils were modeled using five machine learning methods: K-nearest neighbor (KNN), Random Forest (RF), Support Vector Machine (SVM), Partial Least Squares (PLS), and Convolutional Neural Network (CNN). In the qualitative analysis, the Rp2 and RMSEP values ranged from 0.89 to 0.99 and 0.01 to 0.05, respectively. For qualitatively analysis, a threshold of 5 % was established for detecting adulteration in soybean oil with palm oil and sesame oil with palm oil, achieving an accuracy (ACC) greater than 90 %. Meanwhile, a threshold of 10 % was effective for remaining seven adulterated oils, with an ACC exceeding 90 %. Moreover, an ACC rate of over 95 % was attained when the threshold was set at 15 %. The findings demonstrate that 3-D fluorescence spectroscopy presents a robust tool for detecting various adulterated oils, heralding a valuable contribution to food safety and quality control.

Rational biodiesel production by screening different long-term stored plant oils via nuclear magnetic resonance spectroscopic measurement

Screening the raw materials for biodiesel production has normally concentrated on the triglyceride (TAG) content and fatty acid profile without considering the oxidation stability, a crucial restriction factor for commercial life of biodiesel. The traditional screening methods had complex procedures by characterizing the raw material’ and the prepared biodiesel’ properties, which was not applicable for large sets of raw materials. These factors propelled the development of a simple and efficient screening method for potential biodiesel feedstock. Herein, we compared two kinds of spectroscopic measurements, the three-dimensional fluorescence (3D-FL) and high field nuclear magnetic resonance (NMR), for screening special and differential raw materials by investigating 19 plant oil species with one-year storage for biodiesel production. Among these samples, 13 kinds of plant oils contained TAGs, and the other 6 were free of TAGs. The results showed that 3D-FL measurements improperly assigned citronella oil as a TAG-containing plant oil and determined limited information about their chemical composition, suggesting unsatisfactory screening performance. In contrast, 1H NMR measurements screened 3 kinds of differential oils out of those 19 plant oil species, including coconut oil (Cocos nucifera L.), cotton seed oil (Gossypium barbadense L.), palm oil (Elaeis guineensis). Hierarchical clustering analysis (HCA) and partial least square discriminant analysis (PLS-DA) presented that the statistically significant NMR spectral bins for their differential compositions were signals at 3.6 ppm (–OCH3), 2.31 ppm (–OCH2–COOH), 4.29 ppm (TAG skeleton), and 5.27 ppm (TAG skeleton), representing the oxidation products, unsaturated fatty acids, and TAGs. Finally, the converted methyl and ethyl esters (biodiesel) from those three differential plant oil samples were subjected to Rancimat tests. They showed quite different oxidation stabilities from Rancimat tests, which was relevant to the composition differences in the NMR analysis. Our results suggested that the rapid, simple, and reliable NMR measurement combined with HCA and PLS-DA can serve as an efficient tool for potential biodiesel feedstock screening.

Advanced oxidation of bio-treated incineration leachate by persulfate combined with heat, UV254 nm, and UV365 nm: Kinetics, mechanism, and toxicity

This study compared and evaluated the ultraviolet/persulfate (UV/PS) at 254 or 365 nm and heat/persulfate (heat/PS) systems for advanced treatment of biologically pre-treated incineration leachate. The UV365 nm/PS system with the highest removal reduced chemical oxygen demand (COD) by 81.7%, total organic carbon by 73.8%, NH3-N by 96.8%, total nitrogen by 47.3%, and color by 98.6% within 24 h, separately. Kinetics tests suggested that a highest concentrations of 4.8 × 10−10 M for [SO4·-]ss and 2.8 × 10−11 M for [·OH]ss were reported in UV365/PS and UV254/PS systems, respectively. Characterization of leachate organic matter species revealed that low molecular weight organic matter < 5 kDa was preferentially degraded in three systems. Ketones are relatively easily degraded by both heat/PS and UV/PS systems, whereas esters were the most recalcitrant. Three-dimensional fluorescence analysis revealed > 99% humic acid and fulvic acid removal in all three systems. In practical applications, it is crucial to consider the pH and toxicity of SR-AOPs in the treatment of bio-treated incineration leachate. Furthermore, the ecotoxicity of MBR effluent treated by the heat/PS system and UV365 nm/PS system increased, which was caused by the strong acidity exhibited in the systems. In addition, we found that PS could interfere with 3.3% of the COD’s detection. The findings of this study suggest that secondary effects of PS on water quality at high doses should be investigated in future research.