Volatile Gases Research Articles

Influence of coal particle composition and maceral associations on fluidity development during the coking process

Maceral composition is a key parameter used in the assessment of metallurgical coals and coke quality prediction. However, coal particles are typically a mix of different macerals and minerals. Fluidity development in coal particles depends on particle size and the extent of association between constituent maceral grains. As such, determining the composition of coal particles is crucial to understanding the drivers of thermoplastic fluidity. In this work, coal grain analysis (CGA) was used to determine the maceral grain compositional information of individual coal particles for two pairs of metallurgical coals demonstrating different thermoplastic behaviour, as determined by standard Gieseler fluidity and dilatation testing. Each pair was comprised of coals with comparable ranks and both similar (coals A and C) and dissimilar (coals B and D) maceral compositions. The experimental results showed that coals of finer vitrinite particle size and higher degrees of maceral grain association, i.e., finely dispersed macerals within coal particles, demonstrated lower dilatation and higher permeability. It was postulated that coals with close maceral associations are more prone to volatile gas escape during thermoplasticity, hindering bubble growth and thermoswelling while also increasing melt viscosity, leading to decreased Gieseler fluidity measurements. It was also observed that coals with different degrees of maceral grain associations demonstrate different thermoplastic behaviour, where the presence of pure forms of reactive macerals enhanced coal fluidity. Results suggest that some coals possess a higher “effective fluidity” than reported from standard Gieseler testing. Conversely, coals with limited maceral grain association and high compositions of vitrinite prolific particles benefit from enhanced bubble growth and coalescence. Apparent fluidities of such coals are more accurately represented by standard Gieseler testing.

Hierarchical Porous Rod‐Like In2S3/In2O3 Structures for Trimethylamine Detection

AbstractTrimethylamine (TMA), a volatile gas possessing a strong, pungent odor, is widely recognized as an indicator for evaluating fish freshness. Despite the importance of TMA detection, the development of sensors that simultaneously possess high sensitivity, fast response kinetics, selectivity, and low‐temperature operation remains a challenge. To address this issue, this work presents a novel gas‐sensing material composed of porous, rod‐like In2S3/ In2O3 structures, synthesized via an in‐situ sulfurization process. By precisely modulating the sulfurization state of In2O3 through the adjustment of thioacetamide concentrations, the material's structural and compositional properties were optimized for enhanced sensing performance. Experimental results demonstrate that sulfur incorporation significantly improves sensor capabilities, owing to the synergistic effects of the In2S3/ In2O3 heterojunction, the enhanced adsorption capacity for oxygen molecules, and the distinctive one‐dimensional and porous architecture. Notably, the sensor with an S/In molar ratio of 1/3 exhibited exceptional TMA detection at 150 °C, with the highest response values (2.17 for 0.1 ppm and 8.17 for 10 ppm), rapid response/recovery times, excellent selectivity, and a low detection limit of 0.05 ppm. Moreover, the sensor demonstrated outstanding reproducibility and long‐term stability, highlighting its potential for practical applications in seafood freshness monitoring.

Tailoring the performance of the multidimensional electrostatically formed nanowire gas sensor

Abstract Multi-gate field effect transistors (FETs) based on silicon-on-insulator (SOI) have been popular for several decades due to their improved electrostatic control of the channel current between the source and the drain. Chemical sensors based on such multi-gate FET platform can leverage this improved electrostatic control to detect gases at very low concentration with ultrahigh sensitivity. Electrostatically formed nanowire (EFN) is a multiple-gate FET device which has proven to be an excellent platform for detecting volatile organic compounds and gases. In case of such multi-gate FET sensors, it is imperative to rigorously understand the influence of each gate in controlling the sensing performances. Using palladium nanoparticles decorated EFN (Pd-EFN) as an example, the current work presents a detailed methodology for determining the operating parameters for maximal sensing performances of the Pd-EFN sensor towards hydrogen sensing. We observed that a single operating point does not yield best results with regard to sensor response, dynamic range, and power efficiency. By optimising the operating points (by varying the different gate biases), a sensor response of 107 % was reached even at low concentrations of hydrogen (500 ppm) which is significantly lower than the lower explosive limit of 4% and a tunable dynamic range over three decades (4-8000 ppm) was obtained. Also, the sensor response was not compromised at low driving voltages (100 mV) thus contributing to low power consumption of the sensor. Such a correlation between the working point of the transistor and the various sensor performance metrics (maximum sensor response, dynamic range etc ) has not been studied before to the best of our knowledge and this study can be extended to EFN for other gases and any other multi-gate FET sensors (not limited to Si based sensors).This study can pave the way for effective design of future multi-gate transistors for gas sensing.

In situ decoration of AuPd nanoparticles on MOF derived ZnO for ultra-high response and low detection limit trimethylamine detection.

Trimethylamine (TMA) is a colorless, volatile gas with a strong irritating odor. Prolonged exposure to a certain amount of TMA can cause symptoms such as dizziness, nausea and difficulty breathing, and may even be life-threatening. Therefore, effective detection of TMA is crucial. Gas sensors, due to their convenience, affordability and ability to real-time detect volatile gases including TMA, are increasingly favored. However, gas sensors based on single metal oxide materials have numerous drawbacks and may not meet practical requirements. Therefore, it is necessary to modify gas-sensitive materials to achieve sensors with higher sensitivity and selectivity at lower operating temperatures. In this research, gas-sensitive materials for detecting TMA were synthesized using liquid-phase methods. Firstly, metal-organic framework-derived ZnO nanoparticles were prepared via a co-precipitation method, followed by the in-situ reduction method to prepare ZnO modified with Au, Pd, and AuPd bimetallic nanoparticles. The experimental results revealed that when the total loading of AuPd was 2wt% and the ratio was Au:Pd=1:1, the gas-sensitive performance was enhanced significantly. The AuPd-ZnO sensor exhibited a remarkable high response of 1608.3 to 100ppm TMA at 200°C, which was approximately 140 times that of pristine ZnO (Ra/Rg=11.5, 275°C), and the optimal operating temperature was reduced by 75°C. Additionally, the sensor boasted a rapid response time (3s), and low detection limit (50ppb), high selectivity along with good long-term stability. The modified material can enable lower power consumption, increased sensitivity and enhanced stability for real-time detection of TMA. Combined with multiple characterization methods, the sensing mechanism of performance improvement was analyzed, which benefited from the electronic and chemical sensitization of Au and Pd, along with the synergistic effect of the AuPd bimetal. This research provided an effective strategy for the design of high-performance TMA gas sensors.

Natural gas volatility prediction via a novel combination of GARCH-MIDAS and one-class SVM

Research has focused on whether information spillovers from external influences play a role in clean energy–natural gas volatility forecasts. However, the climate and energy crises caused by the intensification of extreme events, such as recent extreme weather and geopolitical risks, have led the public to turn their attention to research in the field of clean energy. Therefore, this paper uses one-class SVM (support vector machine) techniques to identify extreme volatility in natural gas prices induced by significant occurrences (e.g., wars, financial crises, and COVID-19) and then investigates whether considering extreme volatility in natural gas over different volatile periods (short- and long-term periods) improves volatility forecasting accuracy within the context of a GARCH-MIDAS framework. The in-sample analyses demonstrate that extreme shocks increase natural gas price volatility and that the asymmetric effects are more influential than the short- and long-term extreme volatility effects. The out-of-sample results indicate that the GJR-GARCH-MIDAS-one-class-SVM-SLES model outperforms the other models and achieves the best forecasting performance of the remaining extended models. In addition, robustness tests confirm these findings.

Enhancement of room temperature sensitivity and reduction of baseline drift in WO3/g-C3N4 nanocomposite based volatile organic compound gas sensors

Enhancement of room temperature sensitivity and reduction of baseline drift in WO3/g-C3N4 nanocomposite based volatile organic compound gas sensors

A CNT-FET Electronic Nose for the Detection of VOCs Associated with Agriculturally Relevant Pests

Insect infection of post-harvest agricultural yield is detrimental where even a single fruit might spoil the whole batch causing significant economic loss and shortages in the food supply chain. Given this immense loss and the looming food shortages, early detection of spoiled fruits is essential.Upon Infection, fruits emit distinct volatile gases, conveyed even from unblemished waxed fruits. This is especially important as infected fruits may look unblemished and cannot be detected via optical sensors.Therefore, we developed an olfactory biomimetic nanometric electronic field-effect-transistors based on single-walled carbon nanotubes covalently functionalized with polyaniline oligomers doped with silver or copper ions. The volatiles were measured via a dedicated microfluidic system.As a proof of concept, we chose citrus fruits infected by the false codling moth Thaumatotibia leucotreta which attacks various fruits year-round but leaves the fruits unblemished from the outside, and is a common pest throughout the world.We identified specific volatile gases excreted from infected fruits using honey-bees as a biological sensor through Pavlovian conditioning and matched them with the synthetic equivalents.With our devices we were successful in identifying these volatile gases through repeated distinct shift of the transconductance gate response upon exposure to volatile gases. Washing of the device brought about a return to the initial state.Thus, our electronic-nose device can be used as a practical and beneficial tool to detect early infection on fruit batches.

Enhancement of SnO2-Based Gas Sensor Performance through WO3 Receptor Surface Modification

The widespread application of SnO2-based semiconductor gas sensors stems from their exceptional sensitivity and stability in detecting various gases, including volatile organic compounds (VOCs). The fundamental mechanism involves the interaction between the semiconductor material's surface and oxidizing or reducing gases, resulting in a change in electrical resistance. Additionally, the receptor function stands out as a pivotal factor influencing the sensing performance of chemical sensors [1]. Modification of the surface of SnO2 with acidic or basic oxides has been shown to effectively alter its catalytic properties, thereby changing the reaction pathways during ethanol oxidation. This study focuses on an acidic oxide, WO3, which is a promising candidate receptor for improving gas selectivity due to its property of not adsorbing oxygen as well as its high sensitivity to VOC gases. Our previous results demonstrated that similar ethanol consumption rates are observed between neat SnO2 and WO3-loaded SnO2 within the range of 150 to 350℃ during catalytic combustion. Over neat SnO2, dehydrogenation is primarily observed, resulting in CH3CHO being the main product at 150℃, with peak production occurring at 250℃, gradually transitioning to CO2. Furthermore, CO2 generation is initiated at 250℃ and rapidly increases at higher temperatures, attributed to the high catalytic activity of SnO2. Conversely, loading WO3 onto the surface of SnO2 successfully modifies the reaction pathway of ethanol oxidation, with the primary reaction shifting from dehydrogenation to dehydration and selectively generating C2H4 at temperature exceeding 300℃. When materials synthesized by different compositing methods are applied in thick film sensors, the interaction between WO3 and SnO2 significantly influences their sensing properties, with the fine dispersion of WO3 playing a crucial role. Both WO3-loaded and mixed SnO2 exhibited higher responses compared to neat SnO2, with the loaded group showing the highest response to ethanol and acetone. Additionally, 3 mol% WO3-loaded SnO2 demonstrated selective detection properties, with the highest response to 20 ppm acetone at 250℃, which was 22.8 times higher than that of neat SnO2.Efforts have also been made to enhance the gas sensing properties of VOC gases by integrating thermal modulation techniques into miniaturized gas sensors, known as MEMS sensors. These sensors enable operation in a pulse-driven mode [2,3], where the microheater is capable of rapidly heating and cooling the sensor device. Such a driving mode offers selectivity due to the gas adsorption and combustion properties occurring during the heating and cooling phases. By utilizing the pulse-driven mode, it is suggested that during the low-temperature heat-off phase, VOC gases adsorb to the surface of particles, followed by their combustion during the high-temperature heat-on phase. This gas detection model facilitates enhancements in both sensitivity and selectivity, capitalizing on the gas adsorption, diffusion, and catalytic combustion properties on the particle surface. Such developments offer significant improvements in gas detection based on catalytic combustion properties. These insights are crucial for the development of high-performance volatile organic compound gas sensor materials.

Early Sensing of Hazardous Volatile Organic Compounds to Avoid Disastrous Li-Ion Battery Thermal Runaway

Worldwide, lithium-ion batteries (LIBs) applications are growing from kWh (electric vehicle) to GWh (grid storage). Along with LIBs proliferation, the complexities in giga factory level battery manufacturing, large-scale storage, system installations and safe DoD operations became significant with enhanced probabilities to mechanical, electrical, or thermal abuse conditions. Thermal runaway,1 a potential hazard leading to battery failure and even fire and explosions, demands innovative solutions for early detection to prevent catastrophic incidents.Purdue University’s Vilas Pol Energy Research (ViPER) research team innovated scalable, cost effective, and energy efficient polymeric sensor2 for the early detection of volatile organic compounds (VOCs) and various gases released before catastrophic thermal runaway through measuring increased impedance in the LIBs. The studied impedimetric chemosensing of VOCs and vented gases coupled with the battery management system (BMS) is capable of early warning through real time data analysis to the driver/operator, public, fire fighters and first responders on expected toxic and combustible gases.For the proof of concept, submicron (∼0.15 μm) thick poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) sensor film was coated on an interdigitated platinum electrode measuring VOCs at 5, 15, and 30 ppm independently, in various combinations and at different temperatures with DC resistance/impedance spectroscopy.3-5 These preliminary research and development activities (TRL 2) demonstrated that the initial generation of VOCs before final thermal runaway of the cells can be tracked in seconds mitigating catastrophic event from occurring by sudden cooling of the entire system or venting the storage area. The obtained detection results will be discussed with the technology that could avoid LIBs thermal runaway in the field environment. References W. Huang, X. Feng, Y. Pan, C. Jin, J. Sun, J. Yao, H. Wang, C. Xu, F. Jiang and M. Ouyang, J. Energy Storage, 2023, 59, 106536.V. G. Pol, P. Kaur, Methods and Apparatus for sensing volatile organic compounds and gases released from electrochemical cells, US Patent App. 18/107,115.P. Kaur, S. Bagchi, V. G. Pol and A. P. Bhondekar, J. Phys. Chem. C, 2023, 127, 8373–8382.P. Kaur, S. Bagchi, D. Gribble, V. G. Pol and A. P. Bhondekar, ACS Sensors, 2022, 7, 674–682.P. Kaur, I. K. Stier, S. Bagchi, V. G. Pol, A. P. Bhondekar, Batteries, 2023, 9, 1–14.

The Effects of Varied Neutral Detergent Fiber Levels on Blood Parameters, Nutrient Digestibility, Rumen Fermentation Characteristics and Rumen Tissue Morphology in Lambs

Background: Neutral detergent fiber is a common analytical measure of feed fiber content, which could play an important role as an energy source, improve the rumen ecosystem and thus improve growth performance of lambs. The aim of this study was to investigate the effects of different levels of neutral detergent fibers on growth performance, blood parameters, nutrient digestibility, volatile fatty acid concentration, ammonia nitrogen, bacterial quantification, gas production and tissue morphology of growing lambs. Methods: Seventy-two Awassi lambs of weaning age were randomly assigned to three experimental feeds with different levels of neutral detergent fiber: low (210 g/kg), medium (280 g/kg) and high (350 g/kg), each with eight replicates in a completely randomized design. The growth performance parameters were evaluated over a trial period of 84 days. At the end of the trial, hematological and serum biochemical parameters and nutrient digestibility were evaluated. In addition, rumen fermentation characteristics, including pH, ammonia-nitrogen, gas production, volatile fatty acids, bacterial quantification and indices of rumen morphology indices were measured. Result: The results showed that lambs fed a medium-neutral detergent fiber feed had better growth performance (p less than 0.05). In addition, this experimental feed showed improvements in some blood parameters (WBC, RBC, HGB, TP, GLOB and GLU) and nutrient digestibility with the exception of crude protein and ash (p less than 0.05). Rumen fermentation characteristics and rumen morphology were also positively influenced by the medium- neutral detergent fiber level (p less than 0.05). These results indicate that a medium level of neutral detergent fiber (280 g/kg) is essential for optimal growth, health and rumen development in growing lambs.

Development of a Chemical Sensor Device for Monitoring Hazardous Gases Generated in the Semiconductor Manufacturing Process

The semiconductor industry plays a crucial role in various fields but also contributes to environmental degradation. Throughout the semiconductor chip manufacturing process, hazardous gases are released at each stage, despite stringent treatment procedures. These gases can be categorized into four groups: acidic and alkaline gases, volatile organic compounds, flammable and corrosive gases, and greenhouse gases. To meet stricter emission standards, further advancements in gas sensor technology are essential. This review examines recent research on monitoring these gases, highlighting the capabilities and limitations of existing sensor technologies. Additionally, the paper discusses current challenges in gas sensing research and proposes future directions for improving technologies.

Colorimetric sensor array based on metal porphyrin Dye-Modified mesoporous silica nanospheres for quantitative detection of aflatoxin B1 in wheat

This study developed a novel colorimetric sensor array (CSA) based on mesoporous silica nanospheres (MSNs) for the quantitative detection of aflatoxin B1 (AFB1) in wheat. First, 12 kinds of nano-composite color-sensitive materials (Nano-CSMs) were prepared based on MSNs combined with metal porphyrin dyes, and their color-sensitive materials (CSMs) were modified. The volatile gas information of wheat samples with different degrees of mold was collected using two different sensor arrays, and the characteristic maps were visualized. Next, the genetic algorithm (GA) and particle swarm optimization (PSO) were used to screen the optimal characteristic components, and a support vector regression (SVR) model was established to achieve rapid quantitative detection of AFB1. The optimization results show that the SVR model based on Nano-CSA performed best, with a correlation coefficient (Rp) of 0.9754. The results show that the colorimetric sensor array modified by MSNSs has higher sensitivity and efficiency in the detection of AFB1 in wheat.

High-Performance Field-Effect Sensing of Ammonia Based on High-Density and Ultrathin Silicon Nanowire Channels.

Ultrathin silicon nanowires (SiNWs), grown via a high-yield and low-cost catalytic approach, are ideal building blocks for the construction of highly sensitive field-effect transistor (FET) sensors. In this work, we demonstrate a high-density growth integration of an ultrathin SiNW array, with diameter down to DNW = 24 ± 3 nm and narrow NW-to-NW spacing of only 120 nm, fabricated via an in-plane solid-liquid-solid (IPSLS) approach. Junctionless bottom-gated SiNW FETs are successfully constructed, exhibiting a high on/off current ratio of >107 and a sharp subthreshold swing of 156 mV/dec These provide an excellent platform for realizing high-performance NH3 sensing at room temperature, with a high response of 96.9% at 25 ppm and 38.6% at 2.5 ppm, rapid response time of 7.9 s for 5% response (or 85.8 s for 50% response), and superior selectivity against common volatile organic compound gases in ambient environments. Finally, the field-effect sensing mechanism is attributed to the Schottky barrier modulation by the adsorbed NH3 molecules at the metal/SiNW interface, as confirmed through an epoxy-masked selective region comparative analysis. These results provide a solid basis for the ultrathin catalytic IPSLS-SiNWs to serve as advantageous one-dimensional (1D) channels for the scalable integration of various high-performance and flexible gas sensing applications.

The climate crisis - actions to prioritize for anaesthesiologists.

Climate change is the biggest threat to human health and survival in the twenty-first century. Emissions associated with healthcare contribute to climate change and there are many personal and professional actions that can reduce carbon emissions. This review highlights why action is necessary and what anaesthetists and healthcare workers can do. Encouraging continuing research regarding sustainable anaesthesia and expanding education at all levels to include climate action is key. Professionally, actions include limiting use of single-use equipment, reducing reliance on volatile gas inhalational anaesthesia, and adopting low fresh gas flow techniques. Personal actions such as climate-conscious travelling, spending, and eating are important, especially when shared to create climate positive movements. This article shows that, while patient safety and quality of care must remain healthcare's top priority, considering the climate implications of care is part of that duty. Many actions that reduce the carbon impact of care simultaneously improve the quality of care and reduce financial cost. More research into sustainable healthcare is needed. Departments and hospitals and must create environments in which climate conversations are welcomed and can result in positive advancements.

A comprehensive review of treasury management practices and their impact on corporate sustainability in emerging economies: Strategic insights from the oil and gas sector

Treasury management practices are critical for ensuring financial stability and fostering corporate sustainability, particularly in the volatile oil and gas sector of emerging economies. This comprehensive review examines the relationship between treasury management practices and corporate sustainability, focusing on strategic insights that can be drawn from the oil and gas industry. The review highlights the importance of effective cash management, risk assessment, and liquidity optimization as key components of successful treasury operations. The study categorizes treasury management practices into several essential areas, including cash flow forecasting, working capital management, investment strategies, and risk management frameworks. Each category is analyzed concerning its contribution to corporate sustainability, emphasizing the need for a holistic approach that aligns financial objectives with environmental and social considerations. The findings indicate that robust treasury management practices can significantly enhance operational resilience, improve resource allocation, and support long-term sustainability initiatives. Furthermore, the review discusses the challenges faced by oil and gas companies in emerging economies, such as economic instability, regulatory uncertainty, and fluctuating commodity prices. These challenges necessitate the adoption of innovative treasury strategies that not only safeguard financial assets but also promote sustainable business practices. By integrating sustainability metrics into treasury decision-making, companies can better manage risks associated with environmental regulations and stakeholder expectations. Additionally, the role of technology in modernizing treasury management is examined, particularly in terms of digital tools and platforms that enhance data analysis and decision-making capabilities. The review underscores the potential for fintech solutions to streamline treasury operations and improve transparency, thereby contributing to enhanced corporate sustainability. In conclusion, this review provides strategic insights into the interplay between treasury management practices and corporate sustainability in the oil and gas sector of emerging economies. The insights presented herein are intended to guide industry practitioners in developing effective treasury strategies that foster sustainable growth while addressing the unique challenges of the emerging market context.

N, O-codoped carbon aerogel electrode improves capacitive deionization performance

Capacitive deionization (CDI) using porous carbon materials provides an environmentally friendly and sustainable solution to produce affordable fresh water. However, low salt adsorption rates significantly limit its practical application. In this study, N, O-codoped carbon aerogel (NOCA) was prepared by a simple sol–gel method using agar as the carbon framework, NaCl as the template, NH4HCO3 as the nitrogen source and self-blowing agent. The electrochemical and electrosorption properties of the NOCA electrode were significantly better than compared to commercial activated carbon (CAC) electrodes. The NOCA material had the following characteristics: (i) During the rapid freeze-drying process, NaCl crystals provide a three-dimensional network structure for effective dispersion of agar, reducing the agglomeration of particles. The volatile gas generated during the thermal decomposition of NH4HCO3 reduces the plugging of pores. (ii) The fluffy interconnecting network structure of the material enhances its electrical conductivity, providing sufficient channels and adsorption sites for the entry and exit of salt ions. (iii) The abundant hydroxyl and ether groups in the agar enhance the hydrophilicity of the material, whereas N doping further improves the electrical conductivity and reduces the ion transport resistance. The electrosorption capacity and adsorption rate of the NOCA material in 500 mg/L NaCl solution were 22.1 mg/g and 4.4 mg/(g·min), respectively. These values correspond to low energy consumption and high energy recovery efficiency in the electrosorption process. The adsorption capacity remained at 95.5 % after 50 adsorption/desorption cycles. These findings show that NOCA is a novel and potential electrode material for CDI applications.

Phosphorus-nitrogen-containing flame-retardant plasticizers derived from L-lactic acid for poly (lactic acid) improved toughness, flame retardancy and crystallization

Designing highly-effective and environmentally friendly biobased flame-retardant plasticizers for polylactic acid (PLA) remains a formidable challenge. In this study, we synthesized four novel phosphorus-nitrogen-containing L-lactic acid-based flame-retardant plasticizers with adjustable chemical structures and phosphorus content, designated as NPDL-Cn, where ’n’ corresponds to the alkyl groups numbers in the alkylamine chain (with n = 4, 6, 8, and 10). Incorporating NPDL-Cn into the PLA matrix offered a twofold benefit, significantly enhancing both the flame retardancy and toughness of PLA. Remarkably, as incorporating 20 phr NPDL-Cn, the resulting blends all achieved UL-94 V-0 grade, and their limiting oxygen index reached about 30.8 %, 29.5 %, 28.3 % and 27.2 %, respectively. A comprehensive analysis of the volatile gases and char layer generated during combustion showed that the flame-retardant mechanism of NPDL-Cn in PLA significantly influenced both the condensed-phase and gas-phase behavior. Meanwhile, NPDL-Cn effectively overcame the brittleness and rigidity of PLA, thus realizing the enhancement of its toughness. In particular, as compared to a mere 3.7 % and 1.7 MJ/m3 for neat PLA, when the methylene numbers of NPDL-Cn were 4, the elongation at break and tensile toughness of the PLA/NPDL-C4 exhibited a substantial increase to 180.1 % and 43.4 MJ/m3, respectively, due to the best interfacial tension of NPDL-C4 with PLA matrix. Additionally, while the tensile strength of neat PLA is notably high at 50.7 MPa, the introduction of PLA/NPDL-C4 results in a significant decrease to 26.3 MPa. Interestingly, biodegradation experiments showed that NPDL-C4 was decomposed into non-toxic and harmless small molecules. This study presents a method for constructing toughened and flame-retardant PLA blends by modulating the alkyl chain length of flame-retardant plasticizers and elucidating their structure–property relationships.

Politics of International Oil Companies (IOCs): Understanding PETRONAS Carigali Nile Ltd Exit From South Sudanese Oilfields

The study has examined the politics of the International Oil Companies (IOCs), the case study of PETRONAS Carigali Nile Ltd. It does this by appraising the legal violations of PETRONAS Carigali Nile Ltd exit and farming out from South Sudanese oilfields. The study explains the politics of IOCs and particularly, PETRONAS Carigali Nile Ltd as dependent variable and independent variables such as legal violations of Petronas Carigali Nile Ltd, types of residual liabilities and responsibility of these liabilities.The study was subjected to stringent empirical literature review and the gaps in the literature were filled through fieldwork. During fieldwork, the methodology of research tools and instruments such as questionnaires and interview guides/schedules were deployed with target of 52 respondents. Persuasive and cluster type of sampling amongst the senior staff of Ministry of Petroleum (MOP), Nile Petroleum Corporation (NILEPET), Dar Petroleum Operating Company (DPOC), Sudd Petroleum Operating Company (SPOC) and Greater Pioneer Operating Company (GPOC) were applied. The study findings indicate that PETRONAS Carigali Nile Ltd has politicized and violated sections 12, 22, 23, 24, 41 & 42 of the Petroleum Act 2012. Various types of liabilities such as cost recovery audits, environmental audit, petroleum taxes, surface rentals, and cash calls should be taken care off by Petronas Carigali Nile Ltd or by a company that farms into its shares. While the study concludes that PETRONAS Carigali Nile Ltd exit and farming out has been politicized and violated the laws of the Republic of South Sudan, the study recommends that the Ministry of Petroleum should be held responsible for all the legal violations Petronas Carigali Nile Ltd have committed in South Sudan without any action. Whether Savannah Energy Ltd farms into Petronas Carigali Nile Ltd shares or not after the PETRONAS has exited, consequences should be rolled out for such violations so that no any other IOC can do it again in the near future in this volatile oil and gas industry.

A Critical Review of Deep Oxidation of Gaseous Volatile Organic Compounds via Aqueous Advanced Oxidation Processes.

Volatile organic compounds (VOCs) are considered to be the most recalcitrant gaseous pollutants due to their high toxicity, diversity, complexity, and stability. Gas-solid catalytic oxidation methods have been intensively studied for VOC treatment while being greatly hampered by energy consumption, catalyst deactivation, and byproduct formation. Recently, aqueous advanced oxidation processes (AOPs) have attracted increasing interest for the deep oxidation of VOCs at room temperature, owing to the generation of abundant reactive oxygen species (ROS). However, current reviews mainly focus on VOC degradation performance and have not clarified the specific reaction process, degradation products, and paths of VOCs in different AOPs. This study systematically reviews recent advances in the application of aqueous AOPs for gaseous VOC removal. First, the VOC gas-liquid mass transfer and chemical oxidation processes are presented. Second, the latest research progress of VOC removal by various ROS is reviewed to study their degradation performances, pathways, and mechanisms. Finally, the current challenges and future strategies are discussed from the perspectives of synergistic oxidation of VOC mixtures, accurate oxidation, and resource utilization of target VOCs via aqueous AOPs. This perspective provides the latest information and research inspiration for the future industrial application of aqueous AOPs for VOC waste gas treatment.

Metal–organic framework-based SERS chips enable in situ and sensitive detection of dissolved hydrogen sulfide in natural water: Towards a bring-back-chip mode for field analysis

Hydrogen sulfide (H2S) in natural water plays an important role in carbon and sulfur cycles in biosphere. Current detection protocol is complicated, which need to “bring back water” to lab followed by gas chromatograph analysis. In situ, field detection is still challenging. Herein, a portable, sensitive surface enhanced Raman scattering (SERS) chip was proposed for in situ H2S sampling and SERS signal stabilizing, enabling a “bring back chip” manner for lab analysis. The SERS chip was composed of single core-shell gold nanorod-ZIF-8 framework (Au NR@ZIF-8) nanoparticle. Relying on headspace adsorption, evaporated H2S was enriched in the ZIF-8 shell and then reacted with Au NR, resulting in the weakening of the Au-Br bond Raman peak (175 cm−1) and the appearance of the Au-S bond Raman peak (273 cm−1). The SERS signal reached equilibrium in 10 min. The detection range of H2S was 0.1–2000 μg/L and limit of detection was 0.098 μg/L. SERS signal was not interfered by normal volatile gases. Moreover, SERS signal of a reacted chip was stable at an ambient condition, allowing for in situ sampling and bring-back detection. The applicability of the chip was verified by dynamic H2S monitoring during artificial black-odor water evolution, and in-field quantitative analysis of H2S content in river water and sediment. Finally, the chip was sealed in a waterproof breathable membrane device, which realized the detection of vertical profiles of H2S in the river. This work provided a promising tool for field analysis of H2S in natural environments.