Industrial Solvent Research Articles

Intergenerational toxic effects of 1-methyl-3-octylimidazolium chloride and 1-dodecylpyridinium chloride on the water flea, Moina macrocopa.

Ionic liquids (ILs) are generally considered eco-friendly alternatives to conventional industrial solvents, but they are hard to degrade and easily accumulate in the environment. Therefore, their long-term toxicities are especially vital to estimate their potential risk. However, the chronic toxicities of ILs over generations lacked intensive investigation. In the present work, acute toxicity and chronic toxicity of 1-methyl-3-octylimidazolium chloride ([Omim]Cl) and 1-dodecylpyridinium chloride ([DPy]Cl) were studied on Moina macrocopa with the first exposed generation (F0) and two successive recovery generation (F1 to F2). The acute results showed that both [Omim]Cl and [DPy]Cl exhibited high toxicity to M. macrocopa. The chronic results indicated that the exposure of [Omim]Cl and [DPy]Cl could inhibit the survivorship, body length, and reproduction of M. macrocopa and exhibited a significant dose-related decrease. Furthermore, these two types of ILs presented intergenerational toxicity in the water flea. And the toxic effects of [Omim]Cl disappeared in the recovery tests of F2 generation, while the [DPy]Cl toxic effects continued. Our research suggested a potential risk for the aquatic ecosystem induced by ILs. And the damage done by these chemicals to the aquatic environment is worthy of attention.

Evolutionary flexibility and rigidity in the bacterial methylerythritol phosphate (MEP) pathway.

Terpenoids are a diverse class of compounds with wide-ranging uses including as industrial solvents, pharmaceuticals, and fragrances. Efforts to produce terpenoids sustainably by engineering microbes for fermentation are ongoing, but industrial production still largely relies on nonrenewable sources. The methylerythritol phosphate (MEP) pathway generates terpenoid precursor molecules and includes the enzyme Dxs and two iron-sulfur cluster enzymes: IspG and IspH. IspG and IspH are rate limiting-enzymes of the MEP pathway but are challenging for metabolic engineering because they require iron-sulfur cluster biogenesis and an ongoing supply of reducing equivalents to function. Therefore, identifying novel alternatives to IspG and IspH has been an on-going effort to aid in metabolic engineering of terpenoid biosynthesis. We report here an analysis of the evolutionary diversity of terpenoid biosynthesis strategies as a resource for exploration of alternative terpenoid biosynthesis pathways. Using comparative genomics, we surveyed a database of 4,400 diverse bacterial species and found that some may have evolved alternatives to the first enzyme in the pathway, Dxs making it evolutionarily flexible. In contrast, we found that IspG and IspH are evolutionarily rigid because we could not identify any species that appear to have enzymatic routes that circumvent these enzymes. The ever-growing repository of sequenced bacterial genomes has great potential to provide metabolic engineers with alternative metabolic pathway solutions. With the current state of knowledge, we found that enzymes IspG and IspH are evolutionarily indispensable which informs both metabolic engineering efforts and our understanding of the evolution of terpenoid biosynthesis pathways.

Hybrid modeling of drop breakage in pulsed sieve tray extraction columns

Accurate models for pulsed sieve tray extraction columns (PSEs) depend on the correct prediction of the drop diameter to estimate extractive mass transfer across the phase boundary. Phenomenologically, the drop diameter is determined by a balance of drop breakage and coalescence. While for most industrial solvent systems, coalescence plays a minor role; breakage is mostly the dominant phenomenon determining the drop diameter. However, most modeling approaches for drop breakage in PSEs are characterized by a trade-off between a broad validity range and good prediction accuracy. To overcome this limitation, we developed a hybrid breakage model for drop breakage in PSEs in which a physical-empirical model basis is enhanced by data-driven parameter estimator models (PEMs). The hybrid model is based on a revised form of Garthe’s breakage model, for which we developed a linear PEM for the model parameters and two data-driven PEMs for dstab and d100, respectively. The hybrid breakage model was validated on 743 experimental data sets and evaluated based on the pull metric. In a sensitivity analysis, the model correctly predicted the breakage probability over a wide range of solvent properties, operating conditions, and sieve tray geometries. In future studies, the hybrid breakage model can be incorporated into extraction column models without an initial parametrization.

Measurement of the solubility and density of the saturated solution of 3-aminophenol in different pure solvents from 283.1 to 323.1 K: Correlative to pure predictive thermodynamic modeling and molecular dynamic simulation

The solubility of 3-aminophenol was measured in water, isopropanol, ethyl acetate, chloroform, and tert-butyl methyl ether (MTBE) from 283.1 to 323.1 K at atmospheric pressure. In addition, the density of pure solvents and the saturated 3-aminophenol solutions was measured. The experimental solubility data were correlated and predicted using four types of thermodynamic models, including correlative (Wilson, NRTL, and UNIQUAC), semi-predictive (NRTL-SAC, and UNIQAUC-SAC), predictive group contribution methods (UNIFAC, and UNIFAC-DMD), and pure predictive COSMO-SAC model. The NRTL-SAC and UNIQUAC-SAC as semi-predictive models were used to obtain 3-aminophenol conceptual segment numbers, and then, using the NRTL-SAC model, the solubility of 3-aminophenol was predicted in 58 FDA approved solvents in the pharmaceutical industry. The predictive models including UNIFAC and UNIFAC-DMD were also used to predict the 3-aminophenol solubility and compared with the experimental data. The results of the COSMO-SAC model have a large deviation from experimental data. In addition, the experimental solubility data were correlated using the PR equation of state with relative success. The segment-based models such as NRTL-SAC and UNIQUAC-SAC are suggested in the fast solvent screening procedure. Finally, the standard dissolution enthalpy (ΔdisH), the standard dissolution entropy (ΔdisS), and the standard dissolution Gibbs energy (ΔdisG) of 3-aminophenol in the selected solvents were calculated by the Van’t Hoff model and the Gibbs-Helmholtz equation. These values imply that the solubility of 3-aminophenol is an entropy-driven non-spontaneous endothermic process in all chosen single solvents. Using the molecular dynamic (MD) simulation the solvation free energy of 3-aminophenol was calculated. The order of the absolute value of free energy of solvation is as ethyl acetate > isopropanol > MTBE > water > chloroform which is consistent with the order of solubility data.

Purification of hydrogenated oil by microchannel separation coupling hydrocyclone

Hydrogenated oils are commonly used as solvents in the petroleum resin industry. The separation of particulate matter from hydrotreating oil is critical to product quality and the service life of the catalyst in the downstream fixed bed. Conventional separation methods, represented by diatomaceous earth filtration, suffer from low separation efficiency, high material consumption, generation of large amounts of hazardous waste, and cumbersome operation. Therefore, a physical method of microchannel separation coupling hydrocyclone was proposed. A 1 m3/h pilot pretreatment device was established to comprehensively evaluate the particle removal in hydrogenated oil. The high separation efficiency and long operation cycle were achieved by a microchannel separator with 0.5–1 mm particle size quartz sand. The single cycle of the microchannel separator was 75 h. The turbidity was decreased by about 64.3%, which was better than that of the traditional separation method (49.9%). The particle removal in hydrogenated oil by microchannel separator was about 75.0%, while the removal of diatomite separator in the same period was only 44.7%. In a 40 m3/h petroleum resin plant based on a microchannel separator, the operating cost and the hazardous waste emissions are reduced by 1,815,000 CNY/year and 208 tons/year, respectively. It is hoped that this study can not only promote the energy-saving and cleaner production of hydrogenated oil but also provide useful guidance for other petrochemical industries.

Application of interpretable machine learning models to improve the prediction performance of ionic liquids toxicity

With the wide application prospect of ionic liquids (ILs) as solvent in the future industry, in order to promote green and sustainable chemical engineering, the toxicity problem of common concern has been systematically modeled. Machine learning has promoted the development of chemical property prediction model with its powerful data processing ability. Two typical ensemble learning models, Random Forest (RF) and eXtreme Gradient Boosting (XGBoost), were used to model the toxicity of ILs to Vibrio fischeri in this work. The model's hyperparameters were fine-tuned using Bayesian optimization, and its robustness was enhanced through the 5-fold cross validation. The results of the model comparison showed that the XGBoost model exhibited good generalization ability. In addition, the SHapley Additive exPlanations (SHAP) method was used to explain the model in more detail and the XGBoost model was used to supplement the toxicity value matrix of 1590 ILs.

Recent advances in methanol production from methanotrophs.

Methanol, the simplest aliphatic molecule of the alcohol family, finds diverse range of applications as an industrial solvent, a precursor for producing other chemicals (e.g., dimethyl ether, acetic acid and formaldehyde), and a potential fuel. There are conventional chemical routes for methanol production such as, steam reforming of natural gas to form syngas, followed by catalytic conversion into methanol; direct catalytic oxidation of methane, or hydrogenation of carbon dioxide. However, these chemical routes are limited by the requirement for expensive catalysts and extreme process conditions, and plausible environmental implications. Alternatively, methanotrophic microorganisms are being explored as biological alternative for methanol production, under milder process conditions, bypassing the requirement for chemical catalysts, and without imposing any adverse environmental impact. Methanotrophs possess inherent metabolic pathways for methanol production via biological methane oxidation or carbon dioxide reduction, thus offering a surplus advantage pertaining to the sequestration of two major greenhouse gases. This review sheds light on the recent advances in methanotrophic methanol production including metabolic pathways, feedstocks, metabolic engineering, and bioprocess engineering approaches. Furthermore, various reactor configurations are discussed in view of the challenges associated with solubility and mass transfer limitations in methanotrophic gas fermentation systems.

Health risks and environmental influence of volatile organic compounds (VOCs) in a residential area near an industrial park in Southeast China

Industry emission is an important source of anthropogenic volatile organic compounds (VOCs) in China, which have caused elevated ground-level ozone (O3) and fine particulate matter (PM2.5) concentrations and potential adverse human health effects. This study investigated compositions, sources, and health risks of ambient VOCs in a residential area near an industrial park in Southeast China. The concentrations of total VOCs in spring and autumn were 16.7 ± 10.2 ppbv and 14.7 ± 8.35 ppbv, respectively. Alkanes and oxygenated VOCs (OVOCs) were the predominant components that contributed to the ozone formation potential (OFP), while the greatest contribution to secondary organic aerosol formation potential (SOAFP) was due to benzene, toluene, ethylbenzene, and xylene (BTEX). Based on the positive matrix factorization model analysis, the relative contributions of individual VOC sources are as follows: industrial process (49.6% and 53.5% in spring and autumn, respectively), vehicle exhausts (26.9% and 33.2%), solvent usage (17.9% and 8.6%), and biogenic source (5.6% and 4.7%). The carcinogenic risk of benzene in autumn and those of 1,2-dibromoethane in both seasons exceeded the acceptable level of 1.00 × 10−6. The hazard index of the observed 21 toxic VOCs was less than 1, suggesting no non-carcinogenic risk at the monitoring site. This study provides valuable information on public health management by taking effective measures to control benzene and halogenated hydrocarbon pollution from industry.

A study on red cyanine dyes employing bis(fluorosulfonyl)imide anions for color filters of virtual and augmented reality displays

Novel cyanine dyes were designed and synthesized for use in high-resolution OLED red color filters suitable for virtual/augmented reality applications. To enhance stability and solubility in organic solvents, four different weakly coordinating bis(fluorosulfonyl)imide anions were introduced to the cyanine moiety. Additionally, to prevent dye leaching during etching, a substituent containing a methacrylate group was incorporated into the cyanine dye. The spectral properties, solubility in industrial solvents, and stability of the synthesized dyes were investigated to evaluate the dyes for dye-based color filters. Subsequently, spin-coated color filters were fabricated using the optimized photoresists containing the synthesized dyes. The transmittance, chromaticity, and stability of the fabricated color filters were examined. The dyes showed sufficient optical properties and improved solubility in industrial solvents because of their weakly coordinating counter anions. Additionally, the synthesized dyes and prepared color filters exhibited sufficient thermal stability for applications. Furthermore, the prepared color filters exhibited superior transmittances compared to those of their parent dyes.

A facile preparation of high flux NaA zeolite membranes by direct secondary growth of wet gel layer

NaA zeolite membranes were first applied in industrial organic solvent dehydration in 1999. However, issues such as poor reproducibility, low flux, and high cost of NaA zeolite membrane preparation have hindered its industrial progress. In this work, a direct secondary growth of wet gel layer method is employed. Specifically, a wet gel layer is coated to the outer surface of the seeded support, which is then placed into the Teflon-lined autoclave without additional hydrogel inside. Under the conditions of conventional secondary growth (100 °C for 4 h), high flux NaA zeolite membranes can be prepared. The pervaporation performance in the 90 wt% ethanol/water solution is tested at 75 °C, showing the flux up to 4.59 kg m−2 h−1 and the separation factor above 10,000. The controlling factors involved in the preparation of high flux NaA zeolite membranes using the direct secondary growth of wet gel layer are investigated. It is found that the introduction method of the seed layer and wet gel layer, the size of the seed, the state of the gel, and the immersion time play significant roles in the formation of zeolite membranes with superior separation performance. This method provides a new idea for the preparation of high performance, low cost and reproducible zeolite membranes with prospects for industrial application.

Cold extraction of post-salt oil asphaltenes and their solubilization in deep eutectic solvents

The most used oil deasphalting processes are Residuum Oil Supercritical Extraction Kerr-McGee (ROSE), thermal hydrocracking, and liquid-liquid extraction at lower temperatures from 100° to 150°C. All these processes require a large amount of thermal energy, in which the growing global demand for energy emerges the need to improve more efficient, economical, and environmentally friendly techniques. This work proposes a cold extraction asphaltenes process from oil. In addition to removing asphaltenes, the solubilization of asphaltenes in two Deep Eutectic Solvents (DES) (Thymol:C8 Ac. and Menthol:Thymol) is proposed. These solvents have the advantage of lower toxicity, recyclability, and chemical and thermal stability. The study of the use of these solvents in the oil industry is recent and has shown great potential for its application on a large scale. These asphaltenes were solubilized without saturation up to an initial concentration of 7 g/L, maintaining solubilization for 48 h. These results are a basis for future studies on a pilot scale for industrial application and bioconversion of asphaltenes into value-added products.

Spatiotemporal distribution, source apportionment and health risk assessment of atmospheric volatile organic compounds using passive air samplers in a typical coastal area, China

To fully understand source characteristics and human health effects of atmospheric volatile organic compounds (VOCs), it is of great importance to implement long-term measurements, precise source apportionment and simulation. In this study, a 12-month measurement of VOCs was conducted in a coastal area in East China by a novel passive air sampler (PAS). A total of 28 VOC species, mainly in groups of aromatics and halohydrocarbons were observed. The monthly average concentrations of TVOC were as follows: industrial sites (154.10–727.19 μg m−3) > business sites (65.83–86.96 μg m−3) > residential sites (59.63–60.05 μg m−3) > background site (57.62 μg m−3). Their seasonal variation characteristics were: winter > spring > autumn > summer, which was more apparent at industrial sites due to human activities. Six VOC sources including industrial processes, organic solvents, dyeing, plastic synthesis, traffic emissions, and pesticides identified by the positive matrix factorization model compared favorably with the local emissions at industrial sites. Bromoform, hexachloro-1,3-butadiene, C1–C3 halogenated alkanes and benzene homologs could be the important indicators of industrial VOC emissions. The halohydrocarbons and aromatics were the major contributors to the ozone formation potential (OFP) and secondary organic aerosol potential (SOAP) in industrial areas, respectively. Both of OFP and SOAP have their maximum values in winter due to high VOC concentrations. Health risk assessment indicated that a high probability of non-carcinogenic risk (HI > 1) was in the region at 10 m height and 50m radius, and minor carcinogenic risk (CR > 10−6) was in the region at 70 m height and 1000 m radius. Among all the compounds, 1,2-Dibromo-3-chloropropane was the largest contributor with the individual HI value (17.99) and carcinogenic risk (5.34 × 10−3) at the peak. In this study, the PAS as a sampling tool was proven to be reliable and efficient for long-term measurements in coastal areas. It is worth to have further studies to promote passive sampling as an alternative to VOCs monitoring methods.

SET-mediated epigenetic dysregulation of p53 impairs trichloroethylene-induced DNA damage response

Trichloroethylene (TCE) was a widely used industrial solvent, and now has become a major environmental pollutant. Exposure to TCE has been found to result in significant damage to the liver, leading to hepatic toxicity. In our previous study, we discovered that a histone chaperon called SET plays a crucial role in mediating the DNA damage and apoptosis caused by TCE in hepatic cells. However, the precise function of SET in the response to DNA damage is still not fully understood. In this study, we evaluated TCE-induced DNA damage of hepatic L-02 cells with SET-knockdown, then analyzed alterations of H3K79me3 and p53 in hepatic cells and carcinogenic mice livers. Results suggested that SET interferes with DNA response via mediating down-regulation of p53 and partially suppressing H3K79me3 under treatment of TCE. To further verify the regulatory cascade, H3K79me3 was reduced and p53 was knocked down in L-02 cells respectively, and extent of DNA damage was evaluated. Reduced H3K79me3 was found leading to down-regulation of p53 which further exacerbated TCE-induced DNA injury. These findings demonstrated that SET-H3K79me3-p53 served as an epigenetic regulatory axis involved in TCE-induced DNA damage response.

환경사회지배구조(ESG) 맥락에서 친환경식품 개념 정립

With climate change-related crises, people started to be aware of the importance of global cooperation and collaboration instead of global competition. In particular, in a situation where climate change-induced food system issues are threatening human survival, a need to have a new approach as to what environmentally sustainable food (ESF) is arises. Unfortunately promoting green food in the traditional paradigm without its proper concept, has often led to a form of green washing. Therefore, with the content analysis, this paper was to re-conceptualizes it in the ESG context. The newly defined concept is ‘sustainable food in the food systems integrating production, farming, processing and global supply chains, which restricts or does not use pesticides, chemical fertilizers, antibiotics and antimicrobial; is not processed using irradiation, industrial solvents, or synthetic food additives; and does not use or reduces using high fructose corn syrup. In addition, ESF is mainly based on locally grown seasonal fruits, vegetables and insects rather than meat and contributing to socially responsible and ethical management ’ This paper suggests that effective ESG strategies should be further established to enhance consumers’ affective utility associated with the newly defined ESF.

Durable LBL microcapsule-based sponges with superhydrophobic/super-oleophilic and photothermal behaviors for oil–water separation

Spills of marine oily pollutants and illegal discharges of industrial organic solvents have severely undermined the natural resources and ecological sustainability. Herein, a versatile and durable modified melamine sponge (MS) was fabricated by integrating with multilayered microcapsules (MCs) and chemical vapor deposition of 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES), namely PFDTES@MCs@MS. The combination of giant microcapsules on the sponge structure imparts the rough surface micro-construction, accompanied by the hydrophobic modification, which enabled PFDTES@MCs@MS to exhibit superhydrophobic/super-oleophilic and self-cleaning capabilities. PFDTES@MCs@MS displayed outstanding oil–water mixtures or emulsions separation capabilities with the separation efficiencies more than 99%. Impressively, PFDTES@MCs@MS preserved mechanical and chemical durability in 100 recycle tests or chronic processes under harsh conditions. In addition, PFDTES@MCs@MS exhibited the remarkable uptake capacity of organic solvents or oils, and the adsorption amount of light or heavy oil was barely impacted with squeezing after the 50 times of circulation. Furthermore, the PFDTES@MCs@MS displayed antibacterial performance. Significantly, the PFDTES@MCs@MS showed superior photothermal conversion capability, the temperature of it increased dramatically to approximately 80 °C within 180 s under simulated sunlight from room temperature (about 25 ℃), and the flux of separating high-viscosity oils was significantly increased. This study presents a novel oil sorption and separation materials with excellent durability and repeatability, which establishes the foundation for the judicious design of innovative weapons to combat the challenging oil spills.

Identification of membrane engineering targets for increased butanol tolerance in Clostridium saccharoperbutylacetonicum

There is a growing interest in the use of microbial cell factories to produce butanol, an industrial solvent and platform chemical. Biobutanol can also be used as a biofuel and represents a cleaner and more sustainable alternative to the use of conventional fossil fuels. Solventogenic Clostridia are the most popular microorganisms used due to the native expression of butanol synthesis pathways. A major drawback to the wide scale implementation and development of these technologies is the toxicity of butanol. Various membrane properties and related functions are perturbed by the interaction of butanol with the cell membrane, causing lower yields and higher purification costs. This is ultimately why the technology remains underemployed. This study aimed to develop a deeper understanding of butanol toxicity at the membrane to determine future targets for membrane engineering. Changes to the lipidome in Clostridium saccharoperbutylacetonicum N1–4 (HMT) throughout butanol fermentation were investigated with thin layer chromatography and mass spectrometry. By the end of fermentation, levels of phosphatidylglycerol lipids had increased significantly, suggesting an important role of these lipid species in tolerance to butanol. Using membrane models and in vitro assays to investigate characteristics such as permeability, fluidity, and swelling, it was found that altering the composition of membrane models can convey tolerance to butanol, and that modulating membrane fluidity appears to be a key factor. Data presented here will ultimately help to inform rational strain engineering efforts to produce more robust strains capable of producing higher butanol titres.

Scalable Aqueous Battery Electrode Processing Strategy to Improve High C-Rate Capability of Lithium-Ion Battery Electrodes

N-methyl-2-pyrrolidone (NMP) is a popular solvent in the battery industry, but its environmental impact has caused a shift towards aqueous-based slurry compositions. However, its use is limited in several nations due to its hazardous effects on humans and the environment. Developing environmentally friendly aqueous processing for electrode manufacturing is crucial as a countermeasure. To implement green and sustainable production method, a water-based battery electrode processing is devised to replace NMP, the standard organic solvent. In addition, the manufacturing procedures of lithium-ion battery electrodes must be tuned for the electrodes to provide equivalent performance to those produced by conventional processing. In this study, we developed a simple aqueous battery electrode manufacturing method to form channels to reduce tortuosity and kinetic limitation of thick, high mass loading LIB battery electrodes and, more importantly, to improve rate performance at high C-rate while ensuring scalability and lowering electrode manufacturing cost

Polyamide thin film nanocomposite with in-situ co-constructed COFs for organic solvent nanofiltration

Organic solvent nanofiltration (OSN) is a novel membrane technology, it has great potential for organic solvent separation and purification due to its advantages of low energy consumption and mild operating conditions. High-performance OSN membranes are essential for OSN technology. Herein, we adopted a straightforward one-step in-situ co-polymerization procedure for the fabrication of a thin film nanocomposite (TFN) OSN membrane having a COFs-polyamide selective layer via doping the COFs reaction monomers, p-phenylenediamine (Pa) and 1,3,5-triformylphloroglucinol (Tp), into the aqueous m-phenylenediamine (MPD) solution and organic trimesoyl chloride (TMC) solution, respectively, during the interfacial polymerization (IP) process. With the ultra-low concentrations used in both MPD and COFs reactive monomers, the optimal TFN OSN membrane, TFN-100-75, achieves an ethanol permeance of 65.7 L m−2 h−1 MPa−1 and an Rhodamine B (RDB, 479 Da) rejection of 99.0%. Meanwhile, this OSN membrane has an ultra-smooth surface, corresponding to a roughness of only 2.9 ± 0.3 nm. Also, this membrane has larger porosity, average pore size, and surface pore density compared with the COFs-free thin-film composite (TFC) membrane. Besides, the TFN-100-75 membrane has a pure methanol and ethanol permeance of 184.3 and 105 L m−2 h−1 MPa−1, respectively, and a molecular weight cut-off (MWCO) of about 362 Da. The TFN-100-75 membrane achieved an rifampicin rejection of above 99% during the separation of rifampicin/ethanol solutions with different concentration as well as the continuous concentration experiment, demonstrating its potential in pharmaceutical separation and purification. During a long-time variable temperature immersion test in pure N,N-dimethylformamide (DMF) at 25 °C for 32 days and then at 80 °C for 24 days, the TFN-100-75 membrane demonstrates superior solvent resistance, where the RDB rejection decreased only by 2%, from 99.0% to 97.0%. The TFN OSN membrane fabricated by the simple process in this work shows better separation performance than most OSN membranes reported in literatures, and has bright prospects for industrial organic solvents treatment.

Catalytic Conversion of Lignin Model Compound and Kraft Lignin over Reduced Ru/C Catalyst

AbstractCatalytic conversion of lignin into valuable liquid products has been a promising approach. Herein, we reported the catalytic conversion of the lignin model compound and Kraft lignin over reduced Ru/C catalyst with different industrial organic solvents using a high‐pressure/ high‐temperature reactor in a nitrogen atmosphere. The results showed reduced Ru/C catalyst is stable for two runs and active for the conversion of the lignin model compound (2‐phenoxy‐1‐phenyl ethanol) with a breaking of the C−O ether bond at high temperature. In the case of Kraft lignin, 2‐butanol and ethanol were potential solvents for the lignin conversion. The Ru/C catalyst enhanced the conversion of lignin, and the highest Kraft lignin conversion (~68 %) was obtained by using ethanol solvent at 220 °C for 1 h reaction. The product distribution with most small phenolic compounds demonstrated the potential of Kraft lignin conversion over the Ru/C catalyst.

Photochemistry in the urban agglomeration along the coastline of southeastern China: Pollution mechanism and control implication

The concentrations of ground-level ozone (O3) in China have undergone a rapid increase in recent years, resulting in adverse impacts on the air quality and climate change. However, limited research has been conducted on the coastal urban agglomerations with increasingly serious O3 pollution. Therefore, in order to better understand in situ photochemistry, comprehensive field observations of O3 and its precursors, coupled with the model simulation, were conducted in autumn of 2019 at six sites in an urban agglomeration along the coastline of southeastern China. Results indicated that O3 pollution in the southern part of the urban agglomeration was more severe than that in the northern part, due to higher levels of O3 precursors and stronger atmospheric oxidation capacity (AOC) in the southern regions. Oxygenated volatile organic compounds (OVOCs), NO2, and CO dominated the total OH reactivity, and the site-average daytime Ox (O3 + NO2) increments correlated well (R2 = 0.94) with the total OH reactivity of CO and VOCs at these sites except for Quanzhou, where industrial emissions (35.1 %) and solvent usages (33.7 %) dominated the VOC sources. However, vehicle exhausts (31.1 %) were the most predominant contributors to the VOC sources at other sites. The results of model simulations showed that net O3 formation rates were larger at the southern sites. Furthermore, O3 production was mainly controlled by VOCs at most sites, but co-limited by VOCs and NOx at Quanzhou. The most significant VOC groups contributing to O3 formation were aromatics and alkenes, with m/p-xylene, toluene, propene, and ethene being the main contributors at these sites. This study offers a more comprehensive understanding of the characteristics and formation of photochemical pollutions on the scale of the urban areas, indicating the critical need to reduce VOC emissions as a means of mitigating their photochemical effects.