Production Of Chemicals Research Articles

From bean to market: exploring the chemical and production dynamics of high-quality Indonesian vanilla

Indonesia’s vanilla industry requires continuous efforts to enhance its quality and safety to ensure its sustainability. The objective of this research is to identify the chemical composition, production constraints, and post-harvest practices impacting vanilla quality. This research investigates the quality of Indonesian vanilla through in-depth interviews with vanilla growers and exporters, as well as quality analysis in the laboratory. Purposive sampling targeted key producers across seven provinces from May to August 2023. Vanilla samples were collected for chemical analysis after a direct interview with each producer. The result shows that the physical and chemical qualities of vanilla products fulfill Indonesian standards (SNI). The vanillin content ranged from 1.21 to 3.50. Establishing universal standards requires considering various vanilla varieties and determining minimum quality attribute values. Due to the risk of theft, vanilla pods are often picked when they are less than 9 months old, before the fruit is fully ripe. This practice results in a drop in quality, particularly in vanillin concentration. Sustainable growth, stakeholder involvement, inclusive business models, education, and contract farming arrangements help navigate challenges like theft and premature harvesting. Advancements in processing methodologies and the selection of clonal materials reinforce the industry’s commitment to enhancing quality.

A genomic analysis reveals the diversity of cellulosome displaying bacteria.

Several species of cellulolytic bacteria display cellulosomes, massive multi-cellulase containing complexes that degrade lignocellulosic plant biomass (LCB). A greater understanding of cellulosome structure and enzyme content could facilitate the development of new microbial-based methods to produce renewable chemicals and materials. To identify novel cellulosome-displaying microbes we searched 305,693 sequenced bacterial genomes for genes encoding cellulosome proteins; dockerin-fused glycohydrolases (DocGHs) and cohesin domain containing scaffoldins. This analysis identified 33 bacterial species with the genomic capacity to produce cellulosomes, including 10 species not previously reported to produce these complexes, such as Acetivibrio mesophilus. Cellulosome-producing bacteria primarily originate from the Acetivibrio, Ruminococcus, Ruminiclostridium, and Clostridium genera. A rigorous analysis of their enzyme, scaffoldin, dockerin, and cohesin content reveals phylogenetically conserved features. Based on the presence of a high number of genes encoding both scaffoldins and dockerin-fused GHs, the cellulosomes in Acetivibrio and Ruminococcus bacteria possess complex architectures that are populated with a large number of distinct LCB degrading GH enzymes. Their complex cellulosomes are distinguishable by their mechanism of attachment to the cell wall, the structures of their primary scaffoldins, and by how they are transcriptionally regulated. In contrast, bacteria in the Ruminiclostridium and Clostridium genera produce 'simple' cellulosomes that are constructed from only a few types of scaffoldins that based on their distinct complement of GH enzymes are predicted to exhibit high and low cellulolytic activity, respectively. Collectively, the results of this study reveal conserved and divergent architectural features in bacterial cellulosomes that could be useful in guiding ongoing efforts to harness their cellulolytic activities for bio-based chemical and materials production.

Pros and cons of airlift and bubble column bioreactors: How internals improve performance

Gas fermentation is a promising technology of high commercial interest, particularly for capturing CO2 and CO from industrial off-gases to reduce greenhouse gas emissions and replace fossil fuels for bulk chemical production. Therefore, evaluating promising bioreactor settings ab initio is a crucial step. Whereas alternate configurations may be tested in laborious scale up studies, the procedure may be accelerated by in silico studies that accompany or even partially replace wet-lab work once the models are validated. In this context, the current study compares various pneumatically agitated reactor types – bubble column reactor (BCR), annulus- and center-rising internal-loop airlift reactor (AR-IL-ALR and CR-IL-ALR), and external-loop airlift reactor (EL-ALR) – to identify advantages and disadvantages for the given application based on computational fluid dynamics (CFD) models. Process performance is optimized by introducing internal structures to guide the flow. Despite a significant increase in the mass transfer coefficient (kLa) through internal modifications, the CR-IL-ALR still exhibited the poorest performance. The optimized AR-IL-ALR demonstrated good mixing and, after introducing an open-cone shaped internal in the head part and a conical bottom, superior mass transfer, achieving an enhancement over 10 % in the mass transfer coefficient to 315 1/h. This study thereby outlines the potential of internal structures for process improvement, as well as the value of a priori in silico design of reactor configurations.

Transcriptional response of Methanosarcina acetivorans to repression of the energy-conserving methanophenazine: CoM-CoB heterodisulfide reductase enzyme HdrED

ABSTRACT Methane-producing archaea are key organisms in the anaerobic carbon cycle. These organisms, also called methanogens, grow by converting substrate to methane gas in a process called methanogenesis. Previous research showed that the reduction of the terminal electron acceptor is the rate-limiting step in methanogenesis by Methanosarcina acetivorans . In order to gain insight into how the cells sense and respond to the availability of the terminal electron acceptor, we designed an experiment to deplete cells of the essential terminal oxidase enzyme, HdrED. We found that the depletion of HdrED in vivo results in a higher abundance of transcripts for methyltransferases ( mtaC2, mtaB3, mtaC3 ), coenzyme B biosynthesis, C1 metabolism, and pyrimidine compounds. In most cases, these changes were distinct from transcript abundance changes observed during the transition from exponential growth to stationary phase cultures. These data implicate the methylotrophic methanogenesis regulator MsrC (MA4383) in CoM-S-S-CoB heterodisulfide sensing and indicate cells have a specific mechanism to sense intracellular ratio of CoM-S-S-CoB, coenzyme M, and coenzyme B thiols and further suggest transcripts encoding translation and methanogenesis functions are controlled by feed-forward regulation depending on substrate availability. IMPORTANCE Methanosarcina is an emerging model archaeon and synthetic biology platform for the production of renewable energy and sustainable chemicals to reduce dependence on petroleum. Research into metabolic networks and gene regulation in this organism and other methanogens will inform genome-scale metabolic modeling and microbial function prediction in uncultured or non-model anaerobes and archaea. This study suggests methanogens use unknown mechanisms to efficiently couple methanogenesis to gene regulation via CoM-S-S-CoB and ATP availability.

Electrocoagulation treatment of wastewater collected from Haldia industrial region: Performance evaluation and comparison of process optimization

This study investigates the treatment of oil-contaminated wastewater with high levels of inorganic substances, suspended solids and turbidity, collected from the Haldia industrial region of India in February 2023. The wastewater, originating from industries such as chemical, petrochemical, textile, and battery manufacturing, presents a complex pollutant load that challenges traditional treatment methods. Electrocoagulation was employed as the treatment technique, with process optimization conducted using Box-Behnken design (BBD) and central composite design (CCD) for key parameters: pH, initial oil concentration, current density, and electrolysis time. The study comprehensively examined the effects of these parameters on turbidity removal. The optimal conditions were determined to be a pH of 7.5, an initial oil concentration of 275 mg/L, a current density of 17.5 mA/cm², and an electrolysis time of 20 min. Under these conditions, CCD outperformed BBD, achieving a desirability score of 93 % compared to 80 % for BBD. The process successfully reduced turbidity from 450 NTU to 56 NTU and total suspended solids (TSS) from 300 mg/L to 102 mg/L. The operation cost of the process was found to range from ₹0.904/m³ to ₹2.71/m³ as the electrolysis time increased from 0.17 to 0.5 h. The study presents a viable solution for industrial wastewater treatment in this region, aligning with the United Nations Sustainable Development Goal (UN SDG) 2030. Additionally, combining electrocoagulation with membrane filtration may enhance comprehensive pollutant removal.

Full-Volatility Reactive Organic Carbon Emissions from Volatile Chemical Products in Mainland China

Full-Volatility Reactive Organic Carbon Emissions from Volatile Chemical Products in Mainland China

Impact of the Indian Ocean Dipole Mode on Planetary Boundary Layer Ozone in China

AbstractThe Indian Ocean Dipole (IOD) mode exerts distinct impacts on the climate in China and can further affect tropospheric ozone. Using long‐term GEOS‐Chem simulations, we found distinct changes in planetary boundary layer ozone throughout China during positive and negative phases of IOD. In summer, ozone shows synchronized increases except in southern China during positive IOD; the ozone increases are dominated by chemical production and transport in northern and western China, respectively. The increased precursor from biogenic emissions contributed to ozone chemical formation in the northern region, and the increased precipitation and decreased solar radiation hindered ozone production in southern China. Ozone changes show good symmetry over most regions during negative IOD. In autumn, the ozone reduction in southern China shares the same reason as summer, while the chemical increase over northern China is affected more by changes in solar radiation and relative humidity than in the precursor emission.

Physiological Effects and Mechanisms of Chlorella vulgaris as a Biostimulant on the Growth and Drought Tolerance of Arabidopsis thaliana.

Microalgae have demonstrated biostimulant potential owing to their ability to produce various plant growth-promoting substances, such as amino acids, phytohormones, polysaccharides, and vitamins. Most previous studies have primarily focused on the effects of microalgal biostimulants on plant growth. While biomass extracts are commonly used as biostimulants, research on the use of culture supernatant, a byproduct of microalgal culture, is scarce. In this study, we aimed to evaluate the potential of Chlorella vulgaris culture as a biostimulant and assess its effects on the growth and drought tolerance of Arabidopsis thaliana, addressing the gap in current knowledge. Our results demonstrated that the Chlorella cell-free supernatant (CFS) significantly enhanced root growth and shoot development in both seedlings and mature Arabidopsis plants, suggesting the presence of specific growth-promoting compounds in CFS. Notably, CFS appeared to improve drought tolerance in Arabidopsis plants by increasing glucosinolate biosynthesis, inducing stomatal closure, and reducing water loss. Gene expression analysis revealed considerable changes in the expression of drought-responsive genes, such as IAA5, which is involved in auxin signaling, as well as glucosinolate biosynthetic genes, including WRKY63, MYB28, and MYB29. Overall, C. vulgaris culture-derived CFS could serve as a biostimulant alternative to chemical products, enhancing plant growth and drought tolerance.

Niobium Pentoxide as an Acid Catalyst: An Overview

The global chemical industry is under increasing pressure to adopt more sustainable practices, as most chemical products exceed environmental safety limits. Given that chemical production largely relies on catalytic processes, the development of solid acid catalysts has become crucial for more sustainable production. Among these catalysts, niobium pentoxide stands out due to its strong acid sites, which remain active in the presence of water, and its stability under hydrothermal conditions. Recent studies have demonstrated that these solids maintain their catalytic activity even in the presence of strong bases, making them unique catalysts. This review explores the potential of niobium pentoxide as an acid catalyst, addressing advances in synthesis techniques, surface modifications, and combinations with other materials to enhance its catalytic performance in sustainable applications, such as biomass conversion and biofuel production, opening new pathways for the production of greener chemicals. Finally, the future perspectives of niobium pentoxide - based catalysts in green chemistry are discussed.

Managing the parasitic honey bee mite Tropilaelaps mercedesae through combined cultural and chemical control methods

The western honey bee (Apis mellifera) is severely impacted by the parasitic Tropilaelaps mercedesae mite, which has the capacity to outcompete Varroa destructor mites (the current leading cause of colony losses) and more rapidly overwhelm colonies. While T. mercedesae is native to Asia, it has recently expanded its geographic range and has the potential to devastate beekeeping worldwide if introduced to new regions. Our research exploited the dependence of T. mercedesae on developing honey bees (brood) by combining a cultural technique (brood break) with U.S. registered chemical products (oxalic acid or formic acid) to manage T. mercedesae infestation. To evaluate this approach, we compared four treatment groups: (1) Brood Break; (2) Brood Break + Formic Acid (FormicPro®); (3) Brood Break + Oxalic Acid dribble (Api-Bioxal®); and (4) untreated Control. We found that the mite infestation rate of worker brood in Control colonies rose from 0.4 to 15.25% over 60 days, whereas all other treatment groups had infestation rates under 0.11% on Day 60. Mite fall assessments showed similar results, whereby Control colonies had 15.48 mites fall per 24 h on day 60 compared to less than 0.2 mites for any other treatment group. Evaluation of colony strength revealed that Brood Break + Formic Acid colonies had slightly reduced adult honey bee populations. No treatment eliminated all mites, so additional measures may be needed to eradicate T. mercedesae if detected in countries that do not currently have T. mercedesae.

Development and Characterization of Thermal Protection Gels for Steel Pipelines Transporting Combustible Materials

Due to low costs, pipelines are commonly used for transporting hazardous substances such as combustible liquids and gasses. Currently, chemical industrial parks and gas production stations have dense pipeline networks. In the case of a pipeline leakage and subsequent fire accident, the adjacent pipelines could be directly impinged by the flame or engulfed in hot smoke, with the potential to result in a chain of accidents and catastrophic consequences. It is thus of practical importance to develop an efficient thermal protection material for pipelines. In this study, a new type of bio-based gel material was prepared for pipeline thermal protection, using guar gum (GG) as the gelling agent, sodium tetraborate (B) as the crosslinking agent and magnesium chloride (MgCl2) as the fire retardant. Firstly, orthogonal experiments were conducted to examine the gelling time of the gel and determine the optimal formulations that meet the protection requirements. Subsequently, water retention, thermal stability and the microstructure of these formulations were analyzed. Finally, the thermal protection performance of the gel formulations was evaluated under the direct impingement of flames or high-temperature smoke. The results indicated that the best performance was achieved by the formulation with GG, B and MgCl2 mass fractions of 2.5, 0.6 and 0.5 wt%, respectively. This formulation also exhibited the best water retention capacity and thermal stability. In the pipeline thermal protection experiments, this formulation achieved effective protection times of 216 s (for a 90 mm diameter) and 312 s (for a 120 mm diameter) for the lower part of the pipeline under direct flame impingement. Under high-temperature smoke impingement, this formulation also showed excellent performance. These research and findings can provide an important foundation for the further development of thermal protection materials for pipelines under fire conditions.

Role of Ionic Strength in Solubility of Salts in India

Purpose: The aim of the study was to assess the role of ionic strength in solubility of salts in India. Methodology: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low cost advantage as compared to a field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries. Findings: Ionic strength increases, the electrostatic interactions between oppositely charged ions in the salt and the surrounding ions in the solution are weakened, leading to changes in solubility. Higher ionic strength often results in greater solubility of salts due to the shielding effect, which reduces ion pairing and prevents precipitation. However, in some cases, extremely high ionic strength may lead to the "salting out" effect, where solubility decreases as ions compete for solvation. This relationship is essential in fields like chemistry and environmental science, where understanding solubility is crucial for processes such as crystallization and precipitation reactions. Implications to Theory, Practice and Policy: Debye-hückel theory, van’t hoff factor and colligative properties theory may be used to anchor future studies on the role of ionic strength in solubility of salts in India. Industries involved in chemical manufacturing and wastewater treatment should adopt protocols that account for ionic strength when designing their processes. Policymakers should establish regulatory frameworks that promote the inclusion of ionic strength considerations in environmental assessments.

Increasing the productivity of oil flax in the Central Non-Black Earth region

Oil fl ax is a valuable oil crop with a wide range of applications, the raw materials of which are used in the food, technical, chemical, pharmaceutical industries and feed production. In terms of metabolism energy content, fl ax seed surpasses the grain of legumes, cereals and oilseeds. Due to the combination of high energy nutritional value and a large content of useful organic elements, fl ax has a unique biological value. In terms of amino acid composition, fl ax seed is similar to soy protein, but it contains less lysine than soy. Flaxseed presscake obtained during oil production is the most valuable among other types of presscake. Adding waste from fl ax seeds to presscake and meal for young livestock is a proven and good preventive measure that allows reducing the use of expensive synthetic drugs. The purpose of the research was to study the possibility of increasing the productivity of oil fl ax in the Central Non-Black Earth region. Under the conditions of the Central part of the Non-Chernozem zone, on sod-podzolic heavy loamy soils, in multifactorial field experiments, comprehensive studies were carried out on the effect of various techniques (previous crop, use of microfertilizers, level of mineral nutrition, chemical measures of weed control) included in the cultivation technology to obtain diff erent levels of the planned yield of oil flax. It was found that for agricultural production it is possible to recommend the use of winter wheat in crop rotation as a predecessor for oil fl ax, application of mineral fertilizer at the rate of N175P20K65, calculated to obtain the planned yield of 2.5 t/ha, treatment of crops with a mixture of herbicides Hacker, VRG, 80 g/ha + Gerbitox, VRK, 0.8 l/ha, microfertilizer Micropolidoc Plus at a dose of 0.5 l/ha in the “herringbone” phase when the fl ax plants are 8–10 cm tall.

Development of a novel process towards an l-malate biorefinery using methanol as feedstock

Malate is primarily obtained from fossil resources. However, growing environmental concerns are rerouting chemical manufacturing to biomanufacturing. Despite significant ‘discovery research’ efforts for sustainable malate production, a successful industrial implementation remains elusive. A novel methanol-based l-malate biomanufacturing process using the methylotrophic bacterium Bacillus methanolicus is designed and the relationship between R&D and techno-economic feasibility is assessed. Two scenarios are modeled and compared using SuperPro Designer®. First, with limited R&D success a 65 g/L titer is achievable. Then with further strain improvement and process development titer is increased to 100 g/L. Four independent design parameters; biomass formation, CO2 evolution, methanol loss and selling price are selected to analyze techno-economic metrics of interest (yield per batch, yield on methanol, unit production cost, and net present value). Sensitivity analysis reveals the dependence of techno-economic feasibility to R&D success, while uncertainty analysis quantifies how uncertainty in process development propagates into uncertainty in process performance.

Profile of Green Chemistry on Chemistry Education Students: Study on Developing Green Chemistry Practical Module to Support Sustainable Development Goals (SDGs)

The Society 5.0 era emphasizes production efficiency by transitioning from conventional to renewable energy sources. Thus, the Society 5.0 Era aligns with one of the goals of the SDGs, which is that industrial processes become more environmentally friendly and more efficient in using energy resources while increasing their value. Green chemistry is a comprehensive approach that designs safe chemicals ranging from environmentally friendly chemical products and processes to reducing the formation of harmful chemical substances. The type of research is descriptive and aimed at describing the student's early understanding of green chemistry. The subject of this study is a student of Prodi Education Chemistry at the University of Muhammadiyah Cirebon. The test instrument consists of 4 description questions compiled to measure the student's initial understanding of green chemistry. The analysis results show that the students understood the terminology for green chemistry. However, students still need to understand the 12 principles of green chemistry and their applications in everyday life.

High-throughput optimization of organic carbon provision strategies enables enhanced arachidonic acid production in novel microalgae

BackgroundMicroalgae are potential sustainable resources for the production of value-added chemicals that can be used as biofuels, pharmaceuticals, and nutritional supplements. Arachidonic acid (ARA), a omega-6 fatty acid, plays a crucial role in infant development and immune response, and can be used in cosmetics and pharmaceuticals. Demand for industrial-scale ARA production is continuously increasing because of its broad applicability. To address this demand, there has been a significant shift towards microorganism-based ARA production. To accelerate large-scale ARA production, it is crucial to select suitable strains and establish optimal culture conditions.ResultsHere, we isolated a novel microalga Lobosphaera incisa CFRC-1, a valuable strain that holds promise as a feedstock for ARA production. Optimal cultivation conditions were investigated using a high-throughput screening method to enhance ARA production in this novel strain. Out of 71 candidates, four organic carbon substrates were identified that could be utilized by L. incisa CFRC-1. Through flask-scale verification, fructose was confirmed as the optimal organic carbon substrate for promoting microalgal growth, total lipid accumulation, and ARA production. Subsequently, we investigated appropriate substrate concentration and cultivation temperature, confirming that the optimal conditions were 30 g L− 1 of fructose and 27 ℃ of temperature. Under these optimized conditions, biomass and ARA production reached 13.05 ± 0.40 g L− 1 and 97.98 ± 7.33 mg L− 1, respectively, representing 9.6-fold and 5.3-fold increases compared to the conditions before optimization conditions. These results achieved the highest biomass and ARA production in flask-scale cultivation, indicating that our approach effectively improved both production titer and productivity.ConclusionsThis study presents a novel microalgae and optimized conditions for enhancing biomass and ARA production, suggesting that this approach is a practical way to accelerate the production of valuable microalgae-based chemicals. These findings provide a basis for large-scale production of ARA-utilizing microalgae for industrial applications.

Air quality improvement at urban bus stops: Optimal air purification placement using CFD

Nitrogen dioxide (NO2) levels are often elevated near roadways due to vehicle emissions, while sulfur dioxide (SO2) is predominantly found near petrochemical complexes as a result of industrial activities such as oil refining and chemical manufacturing. Considering the detrimental effects of these emissions on the environment and human health, the optimal placement of air purification systems at two bus stops in Ulsan, a heavily industrialized city in South Korea, was investigated in this study to reduce NO2 and SO2 concentrations. Computational fluid dynamics (CFD) simulations were performed to identify strategic installation locations, resulting in a significant reduction in pollutant levels. The largest impact was noted for the Deokha Market bus stop, whereby the added health risk (AR) decreased by 1.93 % and the exposure reduction effectiveness (ERE), a measure of air purification system efficiency, increased by 13.8 %. Similarly, at the Hyomun Intersection bus stop, placing the system near the sidewalk led to a significant reduction in AR by 1.60 % and an increase in ERE by 11.63 %. Additionally, air purification systems at Ulsan bus stops are expected to reduce NO2 levels by 9.1 ppb, decreasing mortality risk by 1.44 %, saving 7 lives annually, and yielding an economic benefit of 33.06 million USD.

Biodegradable hydroxylase polyols production from epoxidized palm oleic acid

Recently, the trend of using renewable sources has great attention in the production of polyol chemicals via the epoxidation method. Palm-based polyols produced from the epoxidation and hydroxylation methods usually have low hydroxyl values (below 200 mg KOH/g). This study aimed to synthesize the hydroxylase polyols with a higher hydroxyl value from the renewable source palm oil. The epoxidized palm oleic acid was synthesized using the in situ performic acid, which is obtained from the reaction of formic acid and hydrogen peroxide. The Taguchi method was executed to optimize the epoxidation process for the maximum production of epoxidized oleic acid. Then, optimized epoxidized palm oleic acid was hydroxylated to produce polyols. In addition, the effect of process parameters on the polyol yields was also studied. At the optimum process parameters, the response of relative conversion to oxirane (RCO) with the determination of oxirane oxygen content (OOC) was found at the maximum value of 82%. According to the results, the maximum hydroxyl value produced was 339 mg KOH/g. A kinetic study revealed that the oxirane cleavage by methanol is a second-order reaction whereas the formation of epoxidized palm oleic acid is a first-order reaction.

High Response and ppb-Level Detection toward Hydrogen Sensing by Palladium-Doped α-Fe2O3 Nanotubes.

Developing hydrogen sensors with parts per billion-level detection limits, high response, and high stability is crucial for ensuring safety across various industries (e.g., hydrogen fuel cells, chemical manufacturing, and aerospace). Despite extensive research on parts per billion-level detection, it still struggles to meet stringent requirements. Here, high performance and ppb-level H2 sensing have been developed with palladium-doped iron oxide nanotubes (Pd@Fe2O3 NTs), which have been prepared by FeCl3·6H2O, PdCl2, and PVP electrospinning and air calcination techniques. Various characterization techniques (FESEM, TEM, XRD, and so forth) were used to prove that the nanotube structure was successfully prepared, and the doping of Pd nanoparticles was realized. The experiments show that palladium doping can significantly improve the gas response of iron oxide nanotubes. Specifically, 0.59 wt % Pd@Fe2O3 NTs have high response (Ra/Rg = 41,000), high selectivity, and excellent repeatability for 200 ppm hydrogen at 300 °C. Notably, there was still a significant response at a low detection limit (LOD) of 50 ppb (Ra/Rg = 16.8). This excellent hydrogen sensing performance may be attributed to the high surface area of the nanotubes, the p-n heterojunction of PdO/Fe2O3, which allows more oxygen to be adsorbed on the surface, and the catalytic action of Pd nanoparticles, which promotes the reaction of hydrogen with surface-adsorbed oxygen.

Impacts of tropical cyclone–heat wave compound events on surface ozone in eastern China: comparison between the Yangtze River and Pearl River deltas

Abstract. China has implemented some air pollution management measures in recent years, yet severe ozone pollution remains a significant issue. The southeastern coast of China (SECC) is often influenced by hot extremes and tropical cyclones (TCs), and the two can occur simultaneously (TC–HDs). The compound TC–HDs show a rising trend in the summers of 2014–2019, potentially affecting ozone pollution. Here, we found that surface ozone concentrations over the SECC are more elevated during extremely hot days than the summer climatology. However, compared to extremely hot days alone (AHDs), the maximum 8 h average ozone (MDA8 O3) concentration increases by an average of 6.8 µg m−3 in the Pearl River Delta (PRD) and decreases by 13.2 µg m−3 in the Yangtze River Delta (YRD) during the compound TC–HDs. The meteorological conditions during AHDs favor the chemical production of ozone over the SECC, exhibiting increased temperature and solar radiation and decreased relative humidity. Relative to AHDs, strong northeasterly winds prevail in the SECC during TC–HDs, suggesting the potential of ozone cross-regional transport between YRD and PRD. The process analysis in the chemical transport model (GEOS-Chem) suggests that relative to AHDs, the chemical production of ozone is enhanced in YRD during TC–HDs, while horizontal transport alleviates ozone pollution in YRD but worsens it in PRD through cross-regional transport. The results highlight the significant effects of cross-regional transport in modulating ozone pollution in the two megacity clusters during hot extremes accompanied by TC activities, giving insight into future ozone control measures over the SECC under global warming.