Optimum Preparation Conditions Research Articles

Effects of Bio-Coal Briquette for Residential Combustion on Brown Carbon Emission Reduction

Biomass burning is an important source of brown carbon (BrC) which poses high-risk threats to human health and the environment. In this study, bio-coal briquette (coal mixed with biomass), a promising solid fuel for residential combustion, is proven to be a clean fuel which can effectively reduce BrC emission. First of all, an orthogonal experiment with three factors and three levels on the physical property of bio-briquette was carried out to identify the optimal preparation conditions including the ratio of biomass to anthracite, particle size and molding pressure. Then a combustion experiment of the bio-coal briquetted was implemented in a simulated residential combustion system. BrC emission factors (EFs) were calculated based on the detected black carbon (BC) concentration by an aethalometer, and other optical characteristics for organic components of extract samplers, such as mass absorption efficiency (MAE) and absorption angstrom index (AAE), were also explored. Lastly, composition analysis of BrC by a gas chromatography (GC) tandem mass spectrometer (MS) and direct visible images by scanning electron microscopy (SEM) were investigated to provide more detail information on BrC EFs and property change. It was shown that bio-coal briquette had such low BrC EFs that 70–81% BrC was reduced in comparison with an interpolation value of 100% biomass and 100% coal. Furthermore, the composition of BrC from bio-coal briquette burning was different, which consisted of more substances with strong wavelength dependence. Consequently, although MAE declined by 60% at a 540 nm wavelength, the AAE value of bio-coal briquette only decreased slightly compared with interpolation values. To be more specific, tar balls, the main existing form of BrC, were distributed much more sparsely in the SEM image of bio-coal briquette. To sum up, a positive reduction effect on BrC was discovered in bio-coal briquette. It is evident that bio-coal briquette can serve as an alternative solid fuel for residential combustion, which is beneficial for both human health and the atmosphere.

Soybean protein isolate/chitosan complex-rutin microcapsules

Rutin is a flavonoid polyphenol with excellent biological activity, but due to its instability and poor water solubility, the utilization rate is reduced in vivo. Preparation of rutin microcapsules from soybean protein isolate (SPI) and chitosan hydrochloride (CHC) by composite coacervation can improve this restriction. The optimal preparation conditions were as follows: the volume ratio of CHC/SPI 1:8, pH 6, and total concentration of CHC and SPI 2 %. The rutin encapsulation rate and loading capacity of the microcapsules were 90.34 % and 0.51 % under optimal conditions. The SPI-CHC-rutin (SCR) microcapsules had a gel mesh structure and good thermal stability, and the system was stable and homogeneous after 12 d storage. During in vitro digestion, the release rates of SCR microcapsules in simulated gastric and intestinal fluids were 16.97 % and 76.53 %, respectively, achieving a targeted release of rutin in intestinal fluids; and the digested products were found to exhibit superior antioxidant activity to that of free rutin digests, indicating a good protection of microencapsulation on the bioactivity of rutin. Overall, SCR microcapsules developed in this study effectively enhanced the bioavailability of rutin. The present work provides a promising delivery system for natural compounds with low bioavailability and stability.

Flocculation performance of PCFA composite coagulant for removing nanoparticles

In this study, red mud was used as the main raw material to prepare polyaluminum-ferric chloride (PCFA) with high added value. The effects of the liquid–solid ratio, reaction temperature, reaction time, hydrochloric acid concentration during acid leaching, polymerization time, OH−/Fe molar ratio, and polymerization temperature on the preparation of PCFA were investigated and determined by conducting single-factor optimization experiments under optimal preparation conditions. Characterization results show that the surface of the PCFA flocculant has compact and dense porosity and a dense sheet-like structure, and PCFA contains hydroxyl-bridged iron–aluminum polymers. When the settling time was 30 min, the stirring intensity was 200 rpm; the initial concentration of Nano-titanium dioxide（TiO2-NPs） was 30 mg·L−1; the pH value was 7.0; the dosage of PCFA was 25 mg·L−1, and the optimum removal rates of TiO2-NPs and turbidity were 84.8% and 81.3%, respectively. The flocs produced by PCFA treatment of TiO2-NPs were large and dense. Under optimal flocculation conditions, the average particle size of PCFA-TiO2-NP flocs was 2.98 µm, and the fractal dimension was 1.66. Based on the abovementioned flocculation experimental data, a Grey correlation method was established to evaluate the degree of correlation among factors such as ionic strength, settling time, stirring strength, kaolin concentration, initial concentration, reaction pH value, and dosage and the performance of PCFA coagulation to remove TiO2-NP-containing wastewater. In the reaction system of the PCFA coagulation of TiO2-NPs, the dosage is the most important factor.

Performance of alkali and Cu-modified ZSM-5 during catalytic ozonation of polyvinyl alcohol in aqueous solution.

A novel hierarchical Cu/ZSM-5 was prepared over alkaline treatment and incipient wet impregnation method for the catalytic ozonation of polyvinyl alcohol (PVA). Under the optimum preparation conditions, hierarchical Cu/ZSM-5 exhibited an excellent mineralization performance during the PVA degradation process, and the removal rate of TOC after 60min of reaction was 47.86%, much higher than that of ozonation alone (5.40%). Its high catalytic activity could attribute to the large pore volume (0.27 cm3/g) and pore size (6.51nm) which are beneficial for the distribution of loaded copper and adsorption performance for PVA. Compared to ·OH, 1O2 (2.66 times in 10min) contributed more to the removal of PVA. The degradation of PVA was a combined process of direct ozone oxidation, catalytic ozonation and adsorption. With its high catalytic performance and stability, hierarchical Cu/ZSM-5 has a very broad application prospect in the process of catalytic ozonation of refractory pollutants.

Antibacterial Mesoporous Silica Granules Containing a Stable N-Halamine Moiety.

High-efficacy and regenerable antimicrobial silica granules were prepared via oxa-Michael addition between poly(vinyl alcohol) (PVA) and methylene-bis-acrylamide (MBA) under the catalysis of sodium carbonate in an aqueous solution. Diluted water glass was added, and the solution pH was adjusted to about 7 to precipitate PVA-MBA modified mesoporous silica (PVA-MBA@SiO2) granules. N-Halamine-grafted silica (PVA-MBA-Cl@SiO2) granules were achieved by adding diluted sodium hypochlorite solution. It was found that a BET surface area of about 380 m2 g-1 for PVA-MBA@SiO2 granules and a Cl+% of about 3.80% for PVA-MBA-Cl@SiO2 granules could be achieved under optimized preparation conditions. Antimicrobial tests showed that the as-prepared antimicrobial silica granules were capable of about a 6-log inactivation of Staphylococcus aureus and Escherichia coli O157:H7 within 10 min of contact. Furthermore, the as-prepared antimicrobial silica granules can be recycled many times due to the excellent regenerability of their N-halamine functional groups and can be saved for a long time. With the above-mentioned advantages, the granules have potential applications in water disinfection.

Development and validation of a peptide-mapping procedure for a novel C1 esterase inhibitor

Peptide mapping is a key method for studying the primary structure of proteins. With its sensitivity to the slightest changes in the covalent structure of a protein, this method is applicable both to medicinal product identification at the control stage and to production process stability monitoring.The aim of the study was to develop and validate a peptide-mapping procedure for the identification of a novel highly glycosylated recombinant C1 esterase inhibitor.Materials and methods. The authors studied recombinant human C1 esterase inhibitor products and trypsin. The study involved peptide mapping using reverse-phase high-performance liquid chromatography and high-resolution mass spectrometry. The following statistics were calculated to evaluate the results: mean, standard deviation, and coefficient of variation. The validation parameters included specificity, precision, and robustness.Results. The authors tested several variants of sample preparation for tryptic digests, including additional N-glycanase treatment and complete deglycosylation, and established the optimal conditions for sample preparation and chromatographic separation of C1 esterase inhibitor peptides to obtain consistent chromatographic profiles (peptide maps). The authors identified characteristic peaks and the corresponding relative retention time and area ranges. The absolute retention time of the second (characteristic) peak was approximately 16.5–16.9 minutes. The relative retention times were 2.14–2.21 for peak 9, 2.55–2.64 for peak 12, 2.97–3.14 for peak 14, 3.11–3.29 for peak 15, and 6.20–6.63 for peak 28.Conclusions. The authors developed a peptide-mapping procedure for C1 esterase inhibitors and optimised the conditions to achieve an over 18-hour reduction in sample preparation time. This procedure met the established acceptance criteria for specificity, precision, and robustness.

Enhanced solar-induced photocatalytic removal of antibiotics over molecularly reconstituted graphitic carbon nitride

Promoting the photocatalytic performance of graphitic carbon nitride (g–C3N4) for efficient removal of organic contaminants like antibiotics from wastewater has gained much consideration due to its metal-free uniqueness and environmental friendliness. In this work, the photocatalytic activity of g–C3N4 is greatly enhanced via a hydrothermally molecular dissociation and subsequent calcination reconstitution, which endows g–C3N4 with a large specific surface area, rapid separation of photogenerated electron/holes and strong redox ability. The apparent kinetic constant (k) of tetracycline hydrochloride (TCH) for the sample obtained under the optimal preparation conditions (CN–C–12) is 4.5 times that of pristine g–C3N4, companied with a stable cycling photocatalytic activity. The possible degradation pathways and the toxicological evaluation of the intermediates were analyzed by LC-MS and ECOSAR. Superoxide radicals (∙O2–) and singlet oxygen (1O2) are detected to be the primary reactive species in the photocatalytic degradation of TCH. Additionally, the practical application of CN–C–12 for TCH removal in actual sunlight and treatment of domestic printing and dyeing wastewater was also investigated. This work shows a potential application of the molecular reconstituted g–C3N4 in the photo-catalytically environmental purification.

Efficient removal of Hg0 from cement kiln flue gas using CexFeyOz composite catalyst.

In this study, a kind of CexFeyOz composite with oxygen vacancy structure and strong oxygen storage capacity was prepared by coprecipitation method. Under the condition of no HCl of flue gas, the Hg0 in the flue gas of cement kiln was efficiently and economically removed by using 6-8% oxygen. The results showed that the optimum preparation conditions of the catalyst were Ce-Fe molar ratio of 1-11 and calcination temperature of 550°C. In addition, the reaction temperature, space velocity, the concentration of O2, SO2, and NO had significant effects on the removal efficiency of Hg0 at different rates. More precisely, at the reaction temperature of 350°C, low airspeed, high concentration of O2, and low concentration of SO2 and NO, the efficiency reached the highest value. According to XPS results, the elemental valence of the CexFeyOz composite changed after the reaction. The redox pairs of Ce3+-Ce4+ and Fe3+-Fe2+ had the ability to transfer electrons, which enabled more oxygen adsorbed on the catalyst surface to be converted into O2-, leading to the improvement of the oxidation efficiency of Hg0.

Production and characterization of nanofibrillated cellulose gels simultaneously exhibiting thermally stable green color and oil-in-water emulsion stabilizing capability from Centella asiatica.

Nanofibrillated cellulose (NFC) gels simultaneously exhibiting Pickering stabilizing capability and thermally stable green color were developed for use as food additive in thermally processed food emulsion requiring the expression of color. Chopped Centella asiatica plant was mixed with zinc amino acid chelate solution and subject to autoclaving at 130°C for 2h to form zinc-chlorophylls complex and to remove noncellulosic components. Autoclaved sample was high-shear homogenized at 26,000rpm for 15min and microfluidized at either 80, 120, or 160MPa for 5 passes. An increase in microfluidization pressure resulted in a decrease in NFC diameters; microfluidization at 160MPa did not nevertheless yield any further reduction in the diameters when compared with that at 120MPa. From energy consumption point of view, microfluidization at 120MPa for 5 passes was then noted as optimal condition for preparation of NFC coloring gel; NFC with diameters of 8-42nm and crystallinity index of 35% was obtained. Freshly prepared gel exhibited gel-like behavior and dark green color. Heating at 121°C for 1h did not affect diameters, viscoelasticity, and color of the gel. Addition of the gel at 0.9% or 1.2% (w/w) into soybean oil-in-water emulsion, in combination with high-shear homogenization at 18,000rpm for 5min, resulted in adequate emulsion stability. The emulsion exhibited stable dark green color and no phase separation after heating at 121°C for 1h and during storage for 8 weeks. PRACTICAL APPLICATIONS: Information presented here can serve as a guideline for further development of a multifunctional food ingredient exhibiting thermally stable green color and oil-in-water emulsion stabilizing capability. In other words, one simple ingredient can serve at the same time as both natural food colorant and emulsion stabilizer.

Preparation, Characterization, Release and Antibacterial Properties of Cinnamon Essential Oil Microcapsules

In this study, the antibacterial microcapsules of cinnamon essential oil (CEO) were prepared by complex condensation method. Chitosan quaternary ammonium salt (HACC) combined with gum arabic (GA) was selected as the coated wall material. The optimal preparation conditions of CEO microcapsules (CMSs) were determined by response surface methodology (RSM): the core/wall mass ratio was 1:1, the pH value was 4.5, the mass concentration of CaCl2 was 0.7 wt% and the actual encapsulation rate of microcapsules was 90.72% ± 1.89%. The morphology, size, composition and thermal stability of the prepared CMSs were characterized by scanning electron microscopy (SEM), laser particle size analysis (LPDA), Fourier transform infrared spectroscopy (FTIR), thermogravimetric differential thermal analysis (TG–DTA) and differential scanning calorimetry (DSC). In addition, the in vitro drug release and antibacterial properties of CMS were also evaluated. The results showed that CMS was spherical, with an average particle size of 6.31 µm. The obvious weight loss occurred at 269 °C and the corresponding DSC curve had an obvious exothermic peak at 265.5 °C, which had an increase compared with CEO. Microcapsules can achieve slow release, with the lowest and highest release rates being 19.66% and 49.79%, within 30 days. The drug release curve of essential oil of microcapsules was consistent with a first-order release model named ExpDec1. Based on the above research results, the CMS can effectively improve the stability of essential oil, achieve slow release and prolong the antibacterial effect, indicating its potential applications in food, cosmetics and medicine.

Preparation and mechanism of carbon felt supported iron trioxide and zero-valent iron for enhancing anaerobic digestion performance

Promoting direct interspecies electron transfer (DIET) for methanogenesis via conductive materials is an effective strategy to enhance anaerobic digestion (AD) for methane production. In situ growth of iron trioxide (ITO) and zero-valent iron (ZVI) on carbon felts (CF) was first prepared as composite CF@ITO and CF@ZVI for AD application in this study via hydrothermal deposition and co-precipitation, respectively. The optimal preparation conditions of 2-fold concentration and 120℃ for CF@ITO and of 1-fold concentration for CF@ZVI were determined via batch AD tests adding different iron-carbon composites. Methane production was increased by 47.73% and 34.98%, respectively, for the optimally prepared CF@ITO and CF@ZVI compared to the control. The mechanisms behind were further explored in a more systematic and profound way. Cyclic voltammetry measurements showed that CF@ITO and CF@ZVI had around 10 times higher double-layer capacitance than CF, demonstrating the enhanced conductivity of iron-carbon composites. Fe and fluorescence analysis revealed that both composites increased Fe bioavailability and sludge conductivity potentially via enriching electrochemically active microorganisms and stimulating the secretion of protein-like substances, which enhanced microbial activity for methanogensis. Metagenomic sequencing analysis indicated that both composites enriched the functional genes associated with energy production and conversion, carbon and methane metabolism, and polysaccharide lyase activity. Iron reducing bacteria enhancing carbohydrate metabolic activity were more enriched in sludge after adding composites. Methanothrix capable of undertaking DIET for methanogenesis and electron carrier proteins associated genes were significantly enriched in biofilm on CF@ITO and CF@ZVI, implying the mediation of DIET via both composites and electron carrier proteins. Methanocorpusculum and Methanobacterium via interspecific hydrogen transfer (IHT) for methanogenesis were only significantly enriched in biofilm on CF@ZVI, demonstrating both enhanced DIET and IHT by CF@ZVI.

Preparation and Application of Fe-Al-SiO2 Poly-Coagulants for Removing Microcystis aeruginosa from Water

Novel Fe-Al-SiO2 (FAS) poly-coagulants were prepared by the ball milling method using ferrous sulfate, aluminum sulfate, hydrophobic silica, and sodium carbonate as raw materials. The optimal preparation conditions and effects of preparation parameters on removal efficiencies were obtained by Response Surface Methodology (RSM) and Analysis of Variance (ANOVA). Removal efficiencies were investigated by employing FAS as the poly-coagulant for algae-laden water. Furthermore, obtained FAS samples were characterized by SEM, FTIR, XRD, and TGA. Results showed that the optimal preparation conditions were n(Fe):n(Al) of 2:1, m(Si):m(Fe+Al) of 1:2, and n(CO32−):n(Fe+Al) of 1.75:1, and the most significant influencing factor was n(CO32−):n(Fe+Al). FAS13 prepared under the above condition had the highest coagulation efficiency for simulated algae-laden water. Removal efficiencies for OD680, TP, and residual Al and Fe concentrations were 92.86%, 90.55%, 0.142 mg/L, and 0.074 mg/L, respectively. Nano-sized spherical particles, excellent thermal stability, and functional groups such as Al–O–Si, Fe–O–Si, and Fe–OH, corresponding to Al2Si2O5(OH)4, Fe7Si8O22(OH)2, and Fe2(OH)2CO3, were observed in FAS13. The coagulation performance of FAS13 was splendid when applied in real algae-laden water. The removal rates of TP, OD680, turbidity, and Chl-α were above 93.87%. The residual Al concentration was at the range of 0.057–0.128 mg/L.

Preparation of PVC-LMZO membrane and its lithium adsorption performance from brine

The forming technology of lithium ion sieves is of great significance for their industrial production and application in brine. A PVC-LMZO lithium ion sieve precursor membrane was prepared by blending the zirconium-coated lithium ion sieve precursor LMZO with PVC, PMMA and PVPk30. The adsorption and cyclic performance of the PVC-LMZO membrane obtained after treatment with HCl were studied. The results showed that the optimal condition for membrane preparation is to add 10 wt% PVC, 20 wt% LMZO, 6 wt% PMMA and 2 wt% PVPk30. After treatment with 0.1 mol·L−1 HCl for 2 h, the lithium desorption reached equilibrium, and the manganese loss rate was approximately 0.332 %. After 15 cycles of adsorption and desorption in brine, the Li+ adsorption capacity was lost by only 5.8 % (from 18.33 mg/g to 17.27 mg/g). The PVC-LMZO membrane had high selectivity for Li+ in brine containing a variety of complex ions such as K+, Ca2+, Na+ and Mg2+. The PVC-LMZO membrane has a stable structure and excellent recycling performance, which is conducive to its industrial application. The PVC-LMZO membrane accords with the Langmuir adsorption isotherm model and pseudo-second-order kinetics model, indicating a monolayer chemisorption. The PVC-LMZO membrane has great development potential for extracting lithium from liquid lithium resources such as salt lake brine.

Anisotropy of water dynamics confined in model silica material

Silica microfibers with highly oriented cylindrical mesopores embedded in alumina membrane were used as model system to characterize the water dynamics anisotropy at a picosecond timescale. To reach this goal, we first studied the optimal preparation conditions to obtain longitudinal silica mesopores orientation at macroscopic scale. Accordingly, we characterized the impact of ethanol content and aspiration pressure on the orientation and filling of the mesopores using scanning electron microscopy, transmission electron microscopy, small angle X-ray scattering, and dynamic vapor sorption. Based on the obtained results we selected the most appropriate sample as a model system. The model system was filled with water and used to characterize the dynamics of water molecules in parallel and perpendicular directions using quasi-elastic neutron scattering measurements collected in two orientations at two timescales (7 ps and 30 ps). The results revealed the anisotropy of water dynamics in the silica mesopores and highlighted a larger perpendicular diffusion coefficient compared to the parallel one at both timescales. This suggests that it may be more difficult for water molecules to move from one hydroxyl surface site to another compared to forming a hydrogen bond with a water molecule not adsorbed at the surface.

Preparation of thin-film nanocomposite membrane with alkali-treated nanozeolite to improve the dehydration performance of alcohol solution

BackgroundThin-film nanocomposite (TFN) membrane separates water from alcohols effectively. However, during fabrication of TFN membrane, the dispersion of inorganic nanoparticle in the solvent media limits its used. MethodsNanozeolite, a natural inorganic particle, was modified through alkaline treatment using NaOH or NaHCO3. Both alkaline indeed improved the dispersion of nanozeolite in trimesoyl chloride (TMC)/n-hexane solution. TFN membrane had been prepared through interfacial polymerization of diethylenetriamine (DETA) and TMC, forming a thin selective polyamide layer on top of hydrolyzed polyacrylonitrile (mPAN) support. Significant findingsThe pore size of the nanozeolite was also enlarged due to the etching by the alkaline. Nanozeolite modified with NaHCO3 was dispersed well in the membrane surface, thus increasing its membrane efficiency. At the optimum preparation condition, 0.2 wt% NZ-NaHCO3 treated using 1 M NaHCO3, the TFNNZ-NaHCO3 exhibited the highest flux of 1,869 g∙m2∙h−1 with 99% water concentration in permeate. Furthermore, the modified membrane had a stable performance for long-term, as well as at different operating temperature and alcohol concentration in the feed. Therefore, the right concentration and type of alkaline could improve the property of nanozeolite for preparing high pervaporation membrane.

Preparation of Encapsulated Breakers for Polymer Gels and Evaluation of Their Properties

A common problem associated with conventional gel breakers is that they can cause a premature reduction in gel viscosity at high temperatures. To address this, a urea-formaldehyde (UF) resin and sulfamic acid (SA) encapsulated polymer gel breaker was prepared via in situ polymerization with UF as the capsule coat and SA as the capsule core; this breaker was able to withstand temperatures of up to 120-140 °C. The encapsulated breaker was characterized using scanning electron microscopy (SEM), infrared spectroscopy (FT-IR), and thermogravimetric (TG) analysis. Meanwhile, the dispersing effects of various emulsifiers on the capsule core, and the encapsulation rate and electrical conductivity of the encapsulated breaker were tested. The gel-breaking performance of the encapsulated breaker was evaluated at different temperatures and dose conditions via simulated core experiments. The results confirm the successful encapsulation of SA in UF and also highlight the slow-release properties of the encapsulated breaker. From experimentation, the optimal preparation conditions were determined to be a molar ratio between urea and formaldehyde (nurea:nformaldehyde) of 1:1.8 for the capsule coat, a pH of 8, a temperature of 75 °C, and the utilization of Span 80/SDBS as the compound emulsifier; the resulting encapsulated breaker exhibited significantly improved gel-breaking performance (gel breaking delayed for 9 days at 130 °C). The optimum preparation conditions determined in the study can be used in industrial production, and there are no potential safety and environmental concerns.

Synthesis of ordered mesoporous silica from biomass ash and its application in CO2 adsorption

It is possible to achieve high-value utilization of solid wastes and lower the cost of mesoporous silica synthesis by synthesizing mesoporous silica from solid wastes. In this study, silica was extracted using the alkali fusion method using biomass ash as the starting material. Biomass ash based mesoporous silica was successfully prepared by hydrothermal method with silicon extract solution as silicon source. The optimum conditions for preparation were determined as follows: addition of cetyltrimethylammonium bromide was 0.45g, hydrothermal temperature was 120 °C, hydrothermal time was 24h. The prepared mesoporous silicon was systematically characterized, and the results showed that high surface area (495 m2/g) and ordered pore structure appeared in the synthesized mesoporous silica materials. The synthesized mesoporous silica showed excellent CO2 adsorption performance (0.749 mmol/g) at 25 °C and 1 bar. According to the calculation of adsorption isotherm and thermodynamics, non-linear Freundlich model can fit the adsorption isotherm better and the adsorption heat of mesoporous silica is less than 20 kJ/mol, which belongs to physical adsorption. After five cycles of CO2 adsorption, the adsorption property was still above 90%, and the CO2/N2 adsorption selectivity reached 396.6, showing good regeneration performance and adsorption selectivity. This research can provide a new possibility for the high-value exploitation of biomass ash and reducing the cost of synthetic mesoporous silica.

Optimization of Preparation Conditions and Purity Analysis of Ammonium Ferrous Sulfate

The preparation of ammonium ferrous sulfate is a typical comprehensive experiment in inorganic chemistry in universities, and is also an important part of the chemistry laboratory technology project of the National Vocational Skills Competition. The synthesis method is constantly improving. The traditional preparation experiment of ammonium ferrous sulfate was studied by reduction and green modification, and the purity of the product was analyzed by spectrophotometry. The results show that the optimal experimental conditions are as follows: the raw material of reduced iron powder with fine particle size and uniform particle size is selected, the optimum molar ratio of iron raw material to dilute sulfuric acid is 1:1.2, and the product yield and purity obtained by evaporative crystallization in water bath are higher.

Suspect Screening of Lupin-Produced Phytotoxins in Environmental Samples

Phytotoxins, the secondary metabolites synthesized by plants, are now recognized as a new category of environmental micropollutants. So far, only a limited number of phytotoxins have been detected and reported in terrestrial and aquatic environments, partially due to the analytical challenge involved. In this article, a robust, reliable, and efficient approach, namely Source Supported Suspect Screening (4S), is introduced for high-throughput analysis of phytotoxins from their plant origin to the downstream environmental compartments. The approach was established on an ultrahigh-performance liquid chromatography–electrospray ionization–quadrupole‑time‑of‑flight-mass spectrometry (UHPLC–ESI-QTOF-MS) analytical platform where optimal sample preparation and chromatographic conditions were investigated and a new suspect screening protocol was suggested.

Synthesis of Nanocellulose‐Based Nitrogen‐Doped Carbon Quantum Dots with High Fluorescence Quantum Yields for Multifunctional Applications

AbstractCarbon quantum dots (CQDs) are one of the most promising luminescent nanomaterials for anti‐counterfeiting due to their excellent optical properties, low toxicity, and environmental friendliness. With the development of green chemistry, biomass carbon sources have attracted attention. Herein, nitrogen‐doped carbon quantum dots (N‐CQDs) are synthesized using waste corn bract nanocellulose as the carbon source and L‐histidine as the nitrogen source in a simple and quick one‐step microwave method. It is found that a raw material mass ratio of 1:4, a temperature of 100 °C, and a preparation time of 5 min are the optimum preparation conditions. The fluorescence quantum yield of N‐CQDs obtained under these conditions is 32.64%. Under the excitation of light at a wavelength of 365 nm, the emission peak of N‐CQDs is located at 430 nm and emits blue light. This study also provides a method to prepare fluorescent anti‐counterfeiting films with excellent performance and fluorescent detection probes solely from waste biomass corn bract leaves and L‐histidine.