N-containing Products Research Articles

Simultaneous regulation of nitrogen, sulfur and carbon using biochar during sewage sludge pyrolysis

Due to the complex nature of sewage sludge (SS), how to control the emission of precursor pollutants during its pyrolysis remains a challenge. In this work, the evolution of N, S and C during SS pyrolysis was investigated and biochars were employed to regulate their distribution in the resulting products. The release of N-containing products followed a descending order of NH3>HCN > NO > NO2 and the biochar addition resulted in a reduction of 40.7–54.3 % for these volatiles. The nitrile-N and pyrrolic-N species decreased, while the quaternary-N in residue increased significantly. The emission of S-containing products showed a descending order of COS > SO2>CH3SH > H2S > CS2 and the co-pyrolysis with biochar showed a reduction of 40.6–65.7 % for these products. The relative contents of thiophene-S and sulfoxide-S species increased, while the content of sulfone-S decreased. Biochar incorporation also resulted in a reduction of 67.2 % and 47.4 % for CO and CO2, respectively. Both Raman and XPS analysis indicated an increase in the graphitization degree and a decrease in structural defects.

Revealing the nitrogen migration mechanism during pyrolysis and steam gasification of biomass: A combined ReaxFF MD and DFT study

The biomass pyrolysis/gasification technology takes advantages of high efficiency and carbon neutrality, which is promising for high value-added products fabrication. However, biomass possesses relatively high amount of N especially for seaweeds and municipal sludge wastes, and the lack of N migration mechanism has resulted in emission of N-containing pollutants and limited its industrial application. In this work, a simulation investigation combining reactive force field molecular dynamic and density functional theory calculations was performed to study the conversion mechanisms of N-containing species in the pyrolysis/gasification of biomass processes. The glutamic acid and cellulose were selected as the model compounds of N-containing and typical compositions of biomass, respectively, and six models containing multiple mass ratios of glutamic acid to cellulose and steam to feedstock were constructed. The results show that the majority of nitrogen in the original model is converted towards NH3-N (62%) during glutamic acid pyrolysis by direct cleavage, hydrogen capture, deamination, and decarboxylation. The presence of cellulose effectively inhibits the decomposition of NH3 at high temperature range, thereby increasing the yield of NH3-N (up to 70%) and restraining the conversion of nitrogen into mesomolecules. The introduction of H2O provides a substantial amount of •H radicals, which facilitates the conversion of nitrogen into NH3-N. During DFT calculations, eight reaction pathways for the formation of N-containing products were proposed on the basis of distribution of pyrolysis products. The glutamic acid cleavage reaction achieves the lowest energy barrier, and the deamination of glutamic acid towards a ternary cyclic ether is found to be the most feasible pathway for the NH3 production. This work can provide theoretical support for nitrogen pollutants mitigation during pyrolysis and steam gasification of biomass processes.

Toward sustainable production of N-containing products via nonthermal plasma-enhanced conversion of natural gas resources

Nonthermal plasmas can directly activate and cleave the strong chemical bonds in molecular nitrogen and methane to facilitate the transformation of these inherently stable molecules through the application of electrical energy. Here, we report a low temperature, atmospheric pressure, nonthermal plasma for the “one-pot” synthesis of olefins, alkynes, higher molecular weight hydrocarbons, ammonia, and nitrogen-containing liquids from a representative shale gas feed enriched with nitrogen. We reproducibly observe a wide range of valuable and synthetically challenging gas-phase and liquid-phase products containing C–N, C–C, and N–H bonding by controlling the N2 concentration in the inlet feed stream. In nitrogen-lean regimes, hydrocarbon products dominate (e.g., ethylene, acetylene, etc.), while nitrogen-rich regimes promote incorporation of nitrogen into the products, leading to the formation of ammonia and liquid products containing a variety of functionalities (e.g., nitriles, amines, heterocycles). High resolution electrospray ionization mass spectrometry was used to measure molecular weights and identify the chemical formulas of the liquid products. Van Krevelen diagrams were created and showed many products with compositions around H/C= 2 and N/C= 0.5, indicating the potential importance of intermediate species with these ratios for liquid formation (e.g., CH3CN + H).

Effect of ammonia on N migration and transformation characteristics during coal pyrolysis: Quantum chemical calculations and pyrolysis experiments

The co-firing of the non-carbon fuel, ammonia, with pulverized coal, is an effective way to reduce CO2 emissions in thermal power plants. However, the high nitrogen content of ammonia increases the risk of high NOx emissions during the co-firing process. To achieve low nitrogen combustion of ammonia-coal co-firing, it is necessary to study the impact of ammonia on the N migration and transformation characteristics, during the coal pyrolysis and combustion processes. In this work, the effects of ammonia on the release of N-containing products, during coal pyrolysis, were studied by quantum chemistry calculations and pyrolysis experiments. The theoretical calculation results showed that the mixing of hydrogen-rich ammonia fuel promoted the generation of HCN during coal pyrolysis and increased the energy consumption of HCN generation. Additionally, ammonia-N could be embedded into the coal char structure and exist in the form of N-6. The experimental results indicated that with the temperature increasing, the N content of the coal char and the pyridinic-N increased under the condition of ammonia-coal co-pyrolysis, confirming the microscopic mechanism of ammonia-N embedding into the coal char structure, as indicated by the theoretical calculations. Our work reveals the molecular paths of N migration and transformation and elaborates on the interaction mechanism of ammonia-N and coal-N during the ammonia-coal co-pyrolysis, which has a certain promoting effect on the development of ammonia-coal co-firing mechanism.

Moisture-Assisted Hydroboration of Nitriles and Conversion Thereof to N-Heterocyles and N-Containing Derivatives.

The recent revelation of hidden-borane catalysis has revolutionized the field of catalytic hydroboration in organic synthesis. Many nucleophilic reaction promoters, previously believed to be the catalysts, in fact primarily facilitated the formation of borane (BH3), which subsequently acted as the true catalyst. This revelation prompted us to explore the untapped potential of these unexpected transformations, with a view to simplify hydroboration using more cost-effective and environmentally friendly nucleophilic precatalysts. Via computational studies, we were able to identify that water can actually undertake that role. Herein, we report a study on the simple hydroboration of nitriles, a notoriously challenging yet synthetically valuable class of substrates, using nothing more than moisture as an activating agent. This moisture-assisted nitrile hydroboration process can seamlessly integrate with a range of downstream transformations in a one-pot fashion to produce valuable N-containing products such as symmetrical imines, thioureas, and bis(alcohol)amines as well as N-heterocycles such as pyrroles, pyridines, pyridinium salts, 2-iminothiazolines, and carbazoles.

Production of Oximes Directly from Sustainable Lignocellulose-Derived Aldehydes and Ammonia over HTS-1 Catalyst.

Oxime chemicals are the building blocks of many anticancer drugs and widely used in industry and laboratory. A simple but robust hierarchically porous zeolite (HTS-1) catalyst was prepared by hydrothermal methods and used for the preparation of vanillin oxime from vanillin in NH3 ⋅ H2 O/DIO (v/v 1/10) system. The results of the catalyst characterization showed that the larger pore size and more framework Ti were conducive to promote the transformation of the substrates. The conversion of vanillin and the yield of vanillin oxime were both higher than 99 % under optimized reaction conditions. It was found that the reaction proceeded by oxidation of NH3 to hydroxylamine (NH2 OH), and oximation of hydroxylamine with vanillin to obtain vanillin oxime, where the rate-controlling step was the hydroxylamine formation, and the apparent activation energy was 26.22 kJ/mol. The corresponding oximation products could also be obtained by extending this method to other compounds derived from lignin. Furthermore, the catalytic system was used directly to the conversion of birch biomass to obtain oxime products such as vanillin oxime, syringaldehyde oxime, and furfural oxime etc. This work might give insights into the sustainable production of N-containing high-value products from lignocellulose.

The impact of H-ZSM-5 catalyst on the mechanism of fuel-N conversion during glutamic acid pyrolysis

During the pyrolysis of biomass, Fuel-bound Nitrogen (Fuel-N) is converted into N-containing compounds present in bio-oil and biochar. These compounds are easily oxidized into NOx during subsequent utilization, causing ecological damage. Catalytic fast pyrolysis has emerged as a promising method for denitrogenation in recent years, but the underlying catalyst mechanism still needs to be determined. This study analyzed the impact of catalyst H-ZSM-5 on the mechanism of Fuel-N conversion during the pyrolysis of glutamic acid, a model compound for nitrogenous biomass, through experimental studies and theoretical calculations. According to literature data, the pyrolysis of glutamic acid predominantly yielded the N-containing products pyrrole, glutarimide, and pyrrolidone. The H-ZSM-5 catalyst showed optimum denitrification at 600 ℃, resulting in a 49.62% reduction in the proportion of N-containing compounds. In the catalytic pyrolysis products, the generation of toluene and naphthalene increased. In-situ DRIFTS experiments were consistent with the results of Py-GC-MS experiments, with catalytic pyrolysis promoting deaminations and decarboxylations, decreased imines and nitriles, and increased aromatic hydrocarbons. Additionally, the energy barrier changes of each pyrolysis pathway were calculated based on Density Functional Theory (DFT). The results showed that the H-ZSM-5 catalyst primarily promoted the deamination reaction, followed by the decarboxylation and dehydration condensation reactions, while inhibiting the dehydrogenation reaction. Moreover, the energy barrier for unsaturated hydrocarbon addition reactions was reduced, facilitating the formation of aromatic compounds. The acid sites inside the H-ZSM-5 catalyst weakly interacted with the reactants, making it easier to detach the amino group during catalytic pyrolysis. This study provides a reference for the denitrification of bio-oil and biochar. Subsequent work can realize the regulation of nitrogen conversion by changing the acidity and concentration of catalyst acid sites.

Directional Shunting of Photogenerated Carriers in POM@MOF for Promoting Nitrogen Adsorption and Oxidation.

The efficient catalysis of nitrogen (N2 ) into high-value N-containing products plays a crucial role in the N economic cycle. However, weak N2 adsorption and invalid N2 activation remain two major bottlenecks in rate-determining steps, leading to low N2 fixation performance. Herein, an effective dual active sites photocatalyst of polyoxometalates (POMs)-based metal-organic frameworks (MOFs) is highlighted via altering coordination microenvironment and inducing directional shunting of photogenerated carriers to facilitate N2 /catalyst interaction and enhance oxidation performance. MOFs create more open unsaturated metal cluster sites with unoccupied d orbital possessing Lewis acidity to accept electrons from the 3σg bonding orbital of N2 for storage by combining with POMs to replace bidentate linkers. POMs act as electron sponges donating electrons to MOFs, while the holes directional flow to POMs. The hole-rich POMs with strong oxidation capacity are easily involved in oxidizing adsorbed N2 . Taking UiO-66 (C48 H28 O32 Zr6 ) and Mo72 Fe30 ([Mo72 Fe30 O252 (CH3 COO)12 {Mo2 O7 (H2 O)}2 {H2 Mo2 O8 (H2 O)}(H2 O)91 ]·150H2 O) as an example, Mo72 Fe30 @UiO-66 shows twofold enhanced adsorption of N2 (250.5cm3 g-1 ) than UiO-66 (122.9cm3 g-1 ) at P/P0 =1. And, the HNO3 yield of Mo72 Fe30 @UiO-66 is 702.4µgg-1 h-1 , ≈7times and 24 times higher than UiO-66 and Mo72 Fe30 . This work provides reliable value for the storage and relaying artificial N2 fixation.

Efficient Production of Valuable Aromatic N-Heterocycles from Bio-Polyols by Heterogeneous Catalysis via Controlling Unstable Intermediate Conversion

Efficient and controllable conversion of renewable polyols to valuable N-containing products by heterogeneous catalysis, especially under relativley mild conditions (<200 °C), remains a significant challenge. Here, we develop a method for one-step efficient production of 2-methylquinoxalines (2-MQs), a type of high-value aromatic N-heterocycles, directly from polyols in the presence of supported Pt dehydrogenation catalyst through controllably in situ trapping reactive pyruvaldehyde (PA) intermediate by aryl-1,2-diamine at the temperature of only 140 °C. The presence of aryl-1,2-diamine not only enabled the formation of 2-MQs, but also markedly enhanced the polyols’ carbon utilization to near-quantitative (>98 C%) level. More importantly, organic solvent-enabled kinetics control of competitive reactions associated with PA transformation, i.e., the condensation with aryl-1,2-diamine to produce 2-MQs and the Cannizzaro reaction to form lactic acid, allowed to access the desired 2-MQs in a controllable manner with yields ranging from 12 C% to 81 C%. The application of this approach to attain diverse 2-MQs and analogues of interest in pharmaceutical industry has been demonstrated.

Use of the N–O Bonds in N-Mesyloxyamides and N-Mesyloxyimides To Gain Access to 5-Alkoxy-3,4-dialkyloxazol-2-ones and 3-Hetero-Substituted Succinimides: A Combined Experimental and Theoretical Study

AbstractThe reactivity of N-mesyloxyamides and -imides with bases was studied based on the initial hypothesis of a possible [3,3]-rearrangement. While the intended α-sulfonyloxylation method could not be developed, the formation of valuable N-containing heterocyclic products was found. Treating N-mesyloxyamides with triethylamine gave fully substituted oxazolone products, which are masked α-amino acid derivatives. The products were identified by a computational approach, which revealed that α-lactams are first formed from an initial enolate by an intramolecular nucleophilic substitution. As strained intermediates, they readily rearrange to the oxazolone products. With a cyclic N-mesyloxyimide, elimination to a maleimide was found. This might indicate that sulfonyloxylation has taken place, but the corresponding product probably underwent elimination. Nucleophiles were then added to trap this suspected intermediate by substitution of methanesulfonate. That way, quaternary α-nitrogen- and α-oxygen-substituted succinimides could be formed, which represent a pharmacologically important class that has received much attention for its value in drug design.

Aqueous-phase formation of N-containing secondary organic compounds affected by the ionic strength

The reaction of carbonyl-to-imine/hemiaminal conversion in the atmospheric aqueous phase is a critical pathway to produce the light-absorbing N-containing secondary organic compounds (SOC). The formation mechanism of these compounds has been wildly investigated in bulk solutions with a low ionic strength. However, the ionic strength in the aqueous phase of the polluted atmosphere may be higher. It is still unclear whether and to what extent the inorganic ions can affect the SOC formation. Here we prepared the bulk solution with certain ionic strength, in which glyoxal and ammonium were mixed to mimic the aqueous-phase reaction. Molecular characterization by High-resolution Mass Spectrometry was performed to identify the N-containing products, and the light absorption of the mixtures was measured by ultraviolet-visible spectroscopy. Thirty-nine N-containing compounds were identified and divided into four categories (N-heterocyclic chromophores, high-molecular-weight compounds with N-heterocycle, aliphatic imines/hemiaminals, and the unclassified). It was observed that the longer reaction time and higher ionic strength led to the formation of more N-heterocyclic chromophores and the increasing of the light-absorbance of the mixture. The added inorganic ions were proposed to make the aqueous phase somewhat viscous so that the molecules were prone to undergo consecutive and intramolecular reactions to form the heterocycles. In general, this study revealed that the enhanced ionic strength and prolonged reaction time had the promotion effect on the light-absorbing SOC formation. It implies that the aldehyde-derived aqueous-phase SOC would contribute more light-absorbing particulate matter in the industrial or populated area where inorganic ions are abundant.

Comparison of aqueous secondary organic aerosol (aqSOA) product distributions from guaiacol oxidation by non-phenolic and phenolic methoxybenzaldehydes as photosensitizers in the absence and presence of ammonium nitrate

Abstract. Aromatic carbonyls (e.g., methoxybenzaldehydes), an important class of photosensitizers, are abundant in the atmosphere. Photosensitization and nitrate-mediated photo-oxidation can occur simultaneously, yet studies about their interactions, particularly for aqueous secondary organic aerosol (aqSOA) formation, remain limited. This study compared non-phenolic (3,4-dimethoxybenzaldehyde, DMB) and phenolic (vanillin, VL) methoxybenzaldehydes as photosensitizers for aqSOA formation via guaiacol (GUA) oxidation in the absence and presence of ammonium nitrate (AN) under atmospherically relevant cloud and fog conditions. GUA oxidation by triplet excited states of DMB (3DMB∗) (GUA + DMB) was ∼ 4 times faster and exhibited greater light absorption than oxidation by 3VL∗ (GUA + VL). Both GUA + DMB and GUA + VL formed aqSOA composed of oligomers, functionalized monomers, oxygenated ring-opening species, and N-containing products in the presence of AN. The observation of N-heterocycles such as imidazoles indicates the participation of ammonium in the reactions. The majority of generated aqSOA comprises potential brown carbon (BrC) chromophores. Oligomerization and functionalization dominated in GUA + DMB and GUA + VL, but functionalization appeared to be more important in GUA + VL due to contributions from VL itself. AN did not significantly affect the oxidation kinetics, but it had distinct effects on the product distributions, likely due to differences in the photosensitizing abilities and structural features of DMB and VL. In particular, the more extensive fragmentation in GUA + DMB than in GUA + VL likely generated more N-containing products in GUA + DMB + AN. In GUA + VL + AN, the increased oligomers may be due to VL-derived phenoxy radicals induced by ⚫OH or ⚫NO2 from nitrate photolysis. Furthermore, increased nitrated products observed in the presence of both DMB or VL and AN than in AN alone imply that photosensitized reactions may promote nitration. This work demonstrates how the structural features of photosensitizers affect aqSOA formation via non-carbonyl phenol oxidation. Potential interactions between photosensitization and AN photolysis were also elucidated. These findings facilitate a better understanding of photosensitized aqSOA formation and highlight the importance of AN photolysis in these reactions.

Experimental and DFT study on the migration and transformation mechanism of nitrogen during the pyrolysis of food waste

Pyrolysis technology is an effective way to realize the reduction and recycling of food waste (FW), but the generation of N-containing substances has a great impact on the quality of pyrolysis products and the environment. The present study mainly focused on the migration and transformation mechanism of N during the pyrolysis process of FW, which was investigated by TG-FTIR, GC–MS, and DFT calculation. The experimental results show that NH3 and HCN are the main N-containing gas products, and the N-containing substances in the pyrolysis oil are mainly N-containing heterocycles (21.82%), nitriles (6.43%), and amides (4.00%) at 500 ℃. The proteins in food waste are cleaved into various amino acid molecules at temperatures above 300 ℃. Some amino acid molecules generate NH3 and HCN by removing various groups. Some other amino acid molecules generate N-containing heterocycles, nitriles, amides, and various other N-containing substances by intramolecular de-H2O or intermolecular de-H2O reactions of amino acids or condensation reactions of amino acids with small molecules and transfer to the pyrolysis oil. As the temperature increases, most of the N-containing heterocycles and nitriles will be cleaved and generate HCN.

Recent progress in C–N coupling for electrochemical CO2 reduction with inorganic nitrogenous species in aqueous solution

The electrocatalytic CO2 reduction in aqueous solution mainly involves bond cleavage and formation between C, H and O, and it is highly desirable to expand the bond formation reaction of C with other atoms to obtain novel and valuable chemicals. The electrochemical synthesis of N-containing organic chemicals in electrocatalytic CO2 reduction via introducing N sources is an effective strategy to expand the product scope, since chemicals containing C–N bonds (e.g. amides and amines) are important reactants/products for medicine, agriculture and industry. This article focuses on the research progress of C–N coupling from CO2 and inorganic nitrogenous species in aqueous solution. Firstly, the reaction pathways related to the reaction intermediates for urea, formamide, acetamide, methylamine and ethylamine are highlighted. Then, the electrocatalytic performance of different catalysts for these several N-containing products are summarized and classified. Finally, the challenges and opportunities are analyzed, aiming to provide general insights into future research directions for electrocatalytic C–N coupling.

Transformation of nitrogen during solar pyrolysis of algae in molten salt

Molten salt pyrolysis of N-rich algae driven by concentrated solar energy is considered as an economical and environmentally friendly method to prepare N-doped value-added carbon. The transformation of nitrogen during the carbon production process by algae pyrolysis in molten Na2CO3-K2CO3 is investigated in-depth, which contributes to the utilization or treatment of nitrogen-containing products. Algae-N is mainly converted to gasN, and the gas-N yield increases as temperature rises, reaching 75.7 wt.% at 900 °C. Molten salt reduces the release temperature of all N-containing gas, captures 89.6% of HCN as CN−, and promotes the release of NH3 and NO. The char-N is dominated by pyrrole-N and quaternary-N at 800–900 °C due to the promotion of molten salt and higher temperature. The major contributors to the bio-oil-N yield are pentadecanenitrile, isoamyl cyanide, benzyl nitrile, styryl cyanide, pyrrole and indole. Nitriles and indoles are promising N-containing products in value-added carbon production, while NH3 and NO are primary pollution gas to be controlled.

Accessing secondary amine containing fine chemicals and polymers with an earth-abundant hydroaminoalkylation catalyst

Titanium-catalyzed hydroaminoalkylation has emerged as an atom-economical, earth-abundant synthesis of N-containing products.

Electrochemically Upcycling Waste Nitrogen into Ammonia in a Membrane-Free Alkaline Electrolyzer

Ammonia (NH3) is a primary form of reactive nitrogen (Nr) which is an essential nutrient for all lives on the earth. Over the past century, the anthropological N2-fixing process in the industry (i.e., the Haber-Bosch process) has contributed to a significant portion of NH3 production, and has also led to the continued accumulation of Nr in our ecosystems that has caused alarming and profound damages to the ecosystems as well as human welfare, as the rate of Nr generation is not balanced by the natural nitrification-denitrification process for its elimination. For example, leakage of excessive nitrate (NO3 −) into the water bodies caused by overfertilization of crop fields and discharged streams from food processing facilities has led to the formation of “dead zones” in coastal areas created by eutrophication. Denitrification in nature is also accompanied by the considerable generation of nitrous oxide (N2O) which possesses century-long stability and a 300-time greater potential for greenhouse effect than CO2. Therefore, restoring the balance between the generation and elimination of Nr is a challenging but urgent task faced by our human beings today.Sustainable solutions to this human-induced matter have been actively pursued in recent years either by converting Nr to harmless N2 (i.e., denitrification), or by enhancing the effective circulation and utilization of Nr in the cycle of the nitrogen element. For instance, the electrochemical reduction of nitrate (NO3RR) is a promising approach as it can eliminate Nr without the need for additional oxidant/reductant. Selective NO3RR toward N2 is highly desirable but remains difficult to achieve due to the high activation barrier for linking two N atoms on typical catalyst surfaces, and thus the coexistence of competing pathways toward other N-containing products. Alternatively, if other forms of Nr in waste resources can be converted to NH3 in an electrochemical device, this process will not only alleviate the environmental impacts of those Nr, but also simultaneously produce NH3 that could substantially decrease the NH3 demand from the Haber-Bosch process, reduce the use of fossil-derived H2 in NH3 production, and decelerate the accumulation of Nr.In this work, we seek to develop an electricity-driven process that can convert various forms of Nr in real waste resources into manageable NH3 products. The key component is a membrane-free alkaline electrolyzer (MFAEL) which transforms Nr into NH3 as the sole N-containing product. With the inexpensive and robust MFAEL system, we achieved an ampere-level partial current density towards NH3 production. By properly choosing the conditions of NH3 collection from MFAEL, continuous production of pure NH3-based chemicals can be realized without the need for additional separation procedures. Techno-economic analysis (TEA) suggests the potential economic feasibility of the waste-to-NH3 process by coupling electrodialysis (ED) for Nr concentration and the MFAEL process for Nr conversion, offering an all-sustainable route for upcycling waste N into the highest-demanded N-based chemical product, so that the growing trend of Nr buildup can be largely decelerated and reversed.

Smog Chamber Study on the Role of NOxin SOA and O3Formation from Aromatic Hydrocarbons

China is facing dual pressures to reduce both PM2.5 and O3 pollution, the crucial precursors of which are NOx and VOCs. In our study, the role of NOx in both secondary organic aerosol (SOA, the important constituent of PM2.5) and O3 formation was examined in our 30 m3 indoor smog chamber. As revealed in the present study, the NOx level can obviously affect the OH concentration and volatility distribution of gas-phase oxidation products and thus O3 and SOA formation. Reducing the NOx concentration to the NOx-sensitive regime can inhibit O3 formation (by 42%), resulting in the reduction of oxidation capacity, which suppresses the SOA formation (by 45%) by inhibiting the formation of O- and N-containing gas-phase oxidation products with low volatility. The contribution of these oxidation products to the formation of SOA was also estimated, and the results could substantially support the trend of SOA yield with NOx at different VOC levels. The atmospheric implications of NOx in the coordinated control of PM2.5 and O3 are also discussed.

Molecular transformations of dissolved organic matter during UV/O3-assisted membrane filtration of UASB-treated real textile wastewater

A ceramic membrane reactor (CMR) integrated with in-situ UV/O3 was assessed for post-treatment of the effluent out of an up-flow anaerobic sludge blanket (UASB) reactor treating real textile wastewater, focusing on the transformation of dissolved organic matter (DOM). Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) revealed the transformation of heteroatomic DOM containing S, N or both to simpler DOM containing mainly C, H, and O atoms. The decreased N contents in products (N/C = 0.0249) compared to precursors (N/C = 0.0311) and the higher O/C ratios in the N-containing products suggest the removal of R–NH2 groups accompanying DOM oxidation. While, S-containing compounds in the products had lower O/C and H/C ratios, suggesting a reduced state and the transformation of R–SO3 to R–S–R. H-abstraction and OH addition were identified as the primary oxidation mechanisms, thus enhancing the dominance of highly unsaturated and phenolic DOM in the effluent (70.3%) compared to the feed (56.6%). The double bond equivalent (DBE) was also increased by 26% in the effluent compared to the feed and by 33% in products compared to precursors. These findings help understand the DOM transformation in UV/O3-assisted ceramic membrane reactors and call for comprehensive toxicity analyses of effluents from the advanced oxidation processes.

Structures and Biological Activities of Alkaloids Produced by Mushrooms, a Fungal Subgroup.

Alkaloids are a wide family of basic N-containing natural products, whose research has revealed bioactive compounds of pharmacological interest. Studies on these compounds have focused more attention on those produced by plants, although other types of organisms have also been proven to synthesize bioactive alkaloids, such as animals, marine organisms, bacteria, and fungi. This review covers the findings of the last 20 years (2002–2022) related to the isolation, structures, and biological activities of the alkaloids produced by mushrooms, a fungal subgroup, and their potential to develop drugs and agrochemicals. In some cases, the synthesis of the reviewed compounds and structure−activity relationship studies have been described.