TG-FTIR-MS (Evolved Gas Analysis) of bidi tobacco powder during combustion and pyrolysis

Trace Metals, Crude Protein, and TGA-FTIR Analysis of Evolved Gas Products in the Thermal Decomposition of Roasted Mopane Worms, Sweet Corn, and Peanuts

The thermal behavior of mopane worms (Imbrasia belina), roasted peanuts (Arachis hypogaea L.), and sweet corn (Zea mays L. saccharata) was investigated under inert conditions using the TGA-FTIR analytical technique heated from 64 to 844°C at a heating rate of 20°C/min. The degradation patterns of the food samples differed as sweet corn and peanuts exhibited four degradation stages 188, 248, 315, and 432°C and 145, 249, 322, and 435°C, respectively. Mopane worms displayed three (106, 398, and 403°C). The different decomposition patterns together with the types of evolved gases shown by FTIR analysis justified the varied biochemical and chemical composition of foods. The common evolved gas species between the food samples were H₂O, CO₂, P=O, CO, and CH₄ but mopane worms showed two extra different bands of C-N and N-H. Higher volumes of evolved gases were recorded at temperatures between 276 and 450°C, which are higher than the usual cooking temperature of 150°C. This means that the food maintained its nutritional value at the cooking temperature. Mopane worms were found to contain twice and four times crude protein content than peanuts and corn, respectively. Only total arsenic metal was reported to be above threshold limits.

The Catalytic Effect from Alkaline Elements on the Tar-Rich Coal Pyrolysis

Tar-rich coal has been widely concerned because of its high tar yield. Two kinds of tar-rich coals were studied by Thermogravimetric-Mass spectrometer-Fourier transform infrared (TG-MS-FTIR) to obtain the pyrolysis characteristics. TG-MS-FTIR was used to study the mass loss, gaseous compounds evolution, and functional group information of tar-rich coal during pyrolysis. Mass loss is mainly caused by water release and macromolecular decomposition. The results showed that there were two stages of mass loss in the pyrolysis process. In addition, the gas release signal detected by mass spectrometry is consistent with the functional group information detected by FTIR. The main gaseous products include H2, H2O, CO, CO2, and CH4. In addition, the effect of ash content on the pyrolysis of oil-rich coal and the catalytic effect of internal minerals on coal pyrolysis are also discussed, and the thermal pyrolysis characteristics of coke-rich oil coal are put forward. The results provide a new idea for the study of pyrolysis characteristics of tar-rich coal.

Emission-to-ash detoxification mechanisms of co-combustion of spent pot lining and pulverized coal

In response to the global initiative for greenhouse gas emission reduction, the co-combustion of coal and spent pot lining (SPL) may cost-effectively minimize waste streams and environmental risks. This study aimed to quantify the emission-to-ash detoxification mechanisms of the co-combustion of SPL and pulverized coal (PC) and their kinetics, gas emission, fluorine-leaching toxicity, mineral phases, and migrations. The main reaction covered the ranges of 335-540 °C and 540-870 °C while the interactions occurred at 360-780 °C. The apparent activation energy minimized (66.99 kJ/mol) with 90% PC addition. The rising PC fraction weakened the peak intensity of NaF and strengthened that of Ca₂F, NaAlSiO₄, and NaAlSi₂O₆. The addition of PC enhanced the combustion efficiency of SPL and raised the melting temperature by capturing Na. PC exhibited a positive effect on solidifying water-soluble fluorine and stabilizing alkali and alkaline earth metals. The leaching fluorine concentrations of the co-combustion ashes were lower than did SPL mono-combustion. The main gases emitted were HF, NH₃, NO_x, CO, and CO₂. HF was largely released at above 800 °C. Multivariate Gaussian process model-based optimization of the operational conditions also verified the gas emissions results. Our study synchronizes the utilization and detoxification of SPL though co-combustion and provides insights into an eco-friendlier life-cycle control on the waste-to-energy conversion.

Bumpy structured nanofibrous membrane as a highly efficient air filter with antibacterial and antiviral property

Recently, the pandemic infectious diseases caused by coronavirus have prompted the development of air filter membranes to against infectious agents and protect human health. This research focuses on air filter membrane with antibacterial and antiviral property for high-efficiency particulate matter (PM) removal. Herein, polyamide-6 electrospun nanofibers were anchored with silver nanoparticles through hydrogen-bond. Bumpy nanorough surface and multilevel structure contribute to improve capture capacity, and silver nanoparticles provide a strong ability to inactivate bacteria and virus. In conclusion, this membrane exhibits high PM_2.5 filtration efficiency of 99.99% and low pressure drop of 31 Pa; simultaneous removal of multiple aerosol pollutants, e.g., SO_x, NO_x, methylbenzene, L-Nicotine; superior antibacterial performance against Escherichia coli (Gram negative bacteria) and Staphylococcus aureus (Gram positive bacteria), antiviral property against Porcine Deltacoronavirus and not significant cytotoxicity. Research of air filtration material is important to remove air pollutants and to prevent infection and spread of respiratory infectious diseases.

Multi-response optimization toward efficient and clean (co-)combustions of textile dyeing sludge and second-generation feedstock

The rapid growth of textile dyeing sludge (TDS) necessitates feeding it back into a circular economy in an efficient and clean way. This study aimed to optimize the clean and efficient operational conditions to co-combust TDS and incense sticks (IS). The (co-)-combustions exhibited four distinctive stages of thermal degradation. According to the master-plots method, the reaction mechanisms of reaction order (F2.4 and F1.5), three-dimensional diffusion (D3), and nucleation growth (A1.5) best explained the four stages, respectively. The interaction between TDS and IS exerted an inhibition effect in the range of 400-500 °C and a facilitation effect in the range of 600-1000 °C. At 300 °C as the main reaction temperature, the main evolved gas and functional groups such as CO₂, H₂O, CH₄, C˭O, C-O, and C-H were detected. The addition of IS improved the comprehensive combustion index, inhibited SO₂, but enhanced CO₂, HCN, and NO_x emissions. CaO in IS enabled Fe to remain in TDS and fixed more S in ash. Multi-response optimizations based on the best-fit artificial neural networks revealed the range of 545-605 °C and the co-combustion of 25% TDS and 75% IS as the cleaner and more efficient operational conditions.

Evolution of chemical functional groups during torrefaction of rice straw

The evolution of CHON functional groups during torrefaction of rice straw at 200-300 °C were investigated. The results showed that 300 °C was more suitable for rice straw torrefaction due to the ideal fuel ratio, energy densification, energy-mass co-benefit index and the significantly improved HHV of the torrefied products. The functional groups such as O-H, N-H, C-H, C = O in the solids decreased with rising temperature accompanied by the releases of H₂O, CH₄, CO₂, CO and NH₃, et al. At 300 °C, 40.04% of fuel-N was released in the form of NH₃, HCN, HNCO et al. due to the decomposition of N-A which was the overall N-functionality in the raw rice straw. It is worth noting that the absorbance of NH₃ and HCN has the same order of magnitude as CO. Therefore, the releases of N-containing gases should be highly concerned for the application of torrefaction technology from the environmental perspective.

Novel Insights into the Kinetics, Evolved Gases, and Mechanisms for Biomass (Sugar Cane Residue) Pyrolysis

Biomass, a renewable energy source, via available thermo-chemical processes has both engineering and environmental advantages. However, the understanding of the kinetics, evolved gases, and mechanisms for biomass pyrolysis is limited. We first propose a novel temperature response mechanism for the pyrolysis of sugar cane residue using thermogravimetric analysis-Fourier transform infrared spectrometry-mass spectrometry (TG-FTIR-MS) combined with Gaussian model and two-dimensional correlation spectroscopy (2D COS). The existence and contribution of distinct peaks in TG-FTIR spectra were innovatively distinguished and quantified, and the temperature-dependent dynamics of gas amounts were determined using Gaussian deconvolution. The 2D-TG-FTIR/MS-COS results revealed for the first time that the primary sequential temperature responses of gases occurred in the order: H₂O/CH₄ > phenols/alkanes/aromatics/alcohols > carboxylic acids/ketones > CO₂/ethers > aldehyde groups/acetaldehyde. Subtle sequential changes even occurred within the same gases during pyrolysis. The quantity dynamics and sequential responses of gases were fitted to the combined effects of the order-based, diffusion, and chemical reaction mechanisms for the component degradation. The combination of TG-FTIR-MS, Gaussian model, and 2D COS is a promising approach for the online monitoring and real-time management of biomass pyrolysis, providing favorable strategies for pyrolysis optimization, byproduct recovery, energy generation, and gas emission control in engineering and environmental applications.

Analysis of chemical constituents in mainstream bidi smoke

Bidi, an indigenous form of cigarette in South Asian countries, is popular because of its low cost and multi-flavored variants. Although recent studies have shown that bidi smokers suffer from various adverse health effects including cancer, research on bidi smoke composition and exposure levels is still very limited. In this research, the vapor and particulate phases of bidi were characterized using gas chromatography coupled with mass spectrometry (GC–MS) and Fourier-transform infrared spectrometry (FTIR). The amounts of nicotine, cotinine, indole, substituted phenols, substituted pyridines, and phytol found in different size fractions of the particulate matter collected using a cascade impactor were reported. Due to the low combustibility of the tendu leaf in bidi, a six-second puff interval was used to sample the smoke constituents for analysis. Significant levels of carbon monoxide, hydrogen cyanide, and hydrocarbons like ethylene, methane and 1, 3-butadiene were detected in the mainstream bidi smoke. In addition, 3-methylpyridine, cotinine, α-amyrin, and β-amyrin were also present at high levels in bidi smoke. Despite having less tobacco compared to conventional cigarette, bidi smokers are potentially exposed to significantly higher concentrations of nicotine due to the greater puffing frequency. The non-porous nature and higher moisture content of tendu leaf in bidis compared to cigarette wrapping paper led to higher levels of carbon monoxide and tar in bidi smoke compared to regular cigarette smoke. Results of this study indicate the presence of harmful and carcinogenic chemicals in the mainstream bidi smoke that could be harmful to human health.

Flame retardant vinylon/poly(m-phenylene isophthalamide) blended fibers with synergistic flame retardancy for advanced fireproof textiles

Superior flame retardant textiles are urgently needed to address high fire and heat risks. This study provides a simple and effective strategy to improve the flame retardancy of textiles through a synergistic effect between the blended fibers, and a system with synergistic in flame retardant vinylon (FRV)/poly(m-phenylene isophthalamide) (PMIA) blended fibers is discovered. The FRV/PMIA 50/50 exhibits a much higher time to ignition and a lower peak heat release rate than those of the neat components, indicating a synergistic flame retardancy between constituents. The corresponding mechanism is explored. The residual char layer formed by blended fibers connects together and keeps the original fiber shape, which acts as a barrier slowing heat transmission and gas diffusion. Concurrently, thermal degradation analysis of blended fibers implies that both components mutually interact with each other, resulting in a higher experimental amount of incombustible gases at an early degradation stage and lower experimental amount of combustible gases at a later degradation stage as compared to the theoretical one. Therefore, the synergistic flame retardancy in FRV/PMIA blended fibers is attributed to the actions in the condensed and gas phases during pyrolysis. This work provides an effective strategy to design fireproof textiles.

Combustion performance of biocrude oil from solvolysis liquefaction of Chlorella pyrenoidosa by thermogravimetry-Fourier transform infrared spectroscopy

The kinetic behavior and evolution characteristics of gaseous products during the combustion of biocrude oil from solvolysis liquefaction of Chlorella pyrenoidosa were investigated by thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR). The results indicated the biocrude oil obtained from different ethanol/water mixed ratio had obvious difference with each other. The ignition temperature of biocrude oil from ethanol-water co-solvent was lower than that from pure water solvent, which promoted the comprehensive combustion index. Especially, BO40 (biocrude oil obtained from 40% ethanol content) achieved the lowest ignition temperature (163.4°C) and high comprehensive combustion index (1.24×10^-06min^-2°C^-3). CH, CO, CC, CO₂, CO and HCN were the main gaseous products. Compared to other biocrude oil samples, BO40 had high first peak intensity of CH, CO and CC, and low peak intensity of CO, which performed better combustion characteristic.

Fates of Chemical Elements in Biomass during Its Pyrolysis

Biomass is increasingly perceived as a renewable resource rather than as an organic solid waste today, as it can be converted to various chemicals, biofuels, and solid biochar using modern processes. In the past few years, pyrolysis has attracted growing interest as a promising versatile platform to convert biomass into valuable resources. However, an efficient and selective conversion process is still difficult to be realized due to the complex nature of biomass, which usually makes the products complicated. Furthermore, various contaminants and inorganic elements (e.g., heavy metals, nitrogen, phosphorus, sulfur, and chlorine) embodied in biomass may be transferred into pyrolysis products or released into the environment, arousing environmental pollution concerns. Understanding their behaviors in biomass pyrolysis is essential to optimizing the pyrolysis process for efficient resource recovery and less environmental pollution. However, there is no comprehensive review so far about the fates of chemical elements in biomass during its pyrolysis. Here, we provide a critical review about the fates of main chemical elements (C, H, O, N, P, Cl, S, and metals) in biomass during its pyrolysis. We overview the research advances about the emission, transformation, and distribution of elements in biomass pyrolysis, discuss the present challenges for resource-oriented conversion and pollution abatement, highlight the importance and significance of understanding the fate of elements during pyrolysis, and outlook the future development directions for process control. The review provides useful information for developing sustainable biomass pyrolysis processes with an improved efficiency and selectivity as well as minimized environmental impacts, and encourages more research efforts from the scientific communities of chemistry, the environment, and energy.

Lab-scale thermal analysis of electronic waste plastics

In this work, we experimentally revealed the thermochemical decomposition pathway of Decabromodiphenyl ethane (DBDPE) and tetrabromobisphenol A (TBBPA) containing electronic waste plastics using an online thermogravimetric-fourier transform infrared-mass spectroscopy (TG-FTIR-MS) system, a high resolution gas chromatography/high resolution mass (HRGC-MS) spectroscopy, and a fixed-bed reactor. We found the distribution and species of produced bromides can be easily controlled by adjusting pyrolytic temperature, which is particularly crucial to their recycle. From the analysis of the liquid and solid phase obtained from the fixed-bed reactor, we proposed that the Br radicals formed during the pyrolysis process may be captured by organic species derived from the depolymerization of plastics to form brominated compounds or by the inorganic species in the plastics, and that these species remained in the char residue after pyrolysis. Our work for the first time demonstrates intramolecular oxygen atoms play a pivotal role in the formation of PBDD/Fs that pyrolysis of oxygen-free BFRs is PBDD/Fs-free, whereas pyrolysis of oxygen-containing BFRs is PBDD/Fs-reduced.

The emission of fluorine gas during incineration of fluoroborate residue

The emission behaviors of wastes from fluorine chemical industry during incineration have raised concerns because multiple fluorine products might danger human health. In this study, fluorine emission from a two-stage incineration system during the combustion of fluoroborate residue was examined. In a TG-FTIR analysis BF3, SiF4 and HF were identified as the initial fluorine forms to be released, while fluorine gases of greenhouse effect such as CF4 and SF6 were not found. Below 700 °C, NaBF4 in the sample decomposed to generate BF3. Then part of BF3 reacted with SiO2 in the system to form SiF4 or hydrolyzed to HF. At higher temperatures, the NaF left in the sample was gradually hydrolyzed to form HF. A lab-scale two-stage tube furnace is established to simulate the typical two-stage combustion chamber in China. Experimental tests proved that HF was the only fluorine gas in the flue gas, and emissions of BF3 and SiF4 can be negligible. Thermodynamic equilibrium model predicted that all SiF4 would be hydrolyzed at 1100 °C in the secondary-chamber, which agreed well with the experimental results.

Superoxide Ion: Generation and Chemical Implications

Superoxide ion (O2(•-)) is of great significance as a radical species implicated in diverse chemical and biological systems. However, the chemistry knowledge of O2(•-) is rather scarce. In addition, numerous studies on O2(•-) were conducted within the latter half of the 20th century. Therefore, the current advancement in technology and instrumentation will certainly provide better insights into mechanisms and products of O2(•-) reactions and thus will result in new findings. This review emphasizes the state-of-the-art research on O2(•-) so as to enable researchers to venture into future research. It comprises the main characteristics of O2(•-) followed by generation methods. The reaction types of O2(•-) are reviewed, and its potential applications including the destruction of hazardous chemicals, synthesis of organic compounds, and many other applications are highlighted. The O2(•-) environmental chemistry is also discussed. The detection methods of O2(•-) are categorized and elaborated. Special attention is given to the feasibility of using ionic liquids as media for O2(•-), addressing the latest progress of generation and applications. The effect of electrodes on the O2(•-) electrochemical generation is reviewed. Finally, some remarks and future perspectives are concluded.

Combustion of hazardous biological waste derived from the fermentation of antibiotics using TG-FTIR and Py-GC/MS techniques

The combustion characteristics for three kinds of antibiotics residue (AR) materials were investigated by TG-FTIR and Py-GC/MS technique. The TG results indicated that AR combustion involved three stages, and correlation between the H/C atomic ratio of the raw materials and peak temperature of weight loss for the second stage was obtained. The FTIR spectra identified evolving gaseous products as CO2, CH4, HCNO, NH3, HCN, and NO. An AR material with a low H/C ratio promoted the formation of CO2 and HCN, but suppressed the yields of NH3 and CH4. The Py-GC/MS results suggested that abundant volatiles can be produced, including alkenes, benzene, phenols, furans, acid, and heterocyclic-N, nitrile-N and amine-N compounds, and confirmed the FTIR absorption characteristics in the low temperature range. A possible pathway for the AR combustion was also tentatively presented.

Thermogravimetric and Kinetic Analysis of Raw and Torrefied Biomass Combustion

The use of torrefied biomass as a substitute for untreated biomass may decrease some technological barriers that exist in biomass co-firing technologies e.g. low grindability, high moisture content, low energy density and hydrophilic nature of raw biomass. In this study the TG-MS-FTIR analysis and kinetic analysis of willow (Salix viminalis L.) and samples torrefied at 200, 220, 240, 260, 280 and 300 °C (TSWE 200, 220, 240, 260, 280 and 300), were performed. The TG-DTG curves show that in the case of willow and torrefied samples TSWE 200, 220, 240 and 260 there are pyrolysis and combustion stages, while in the case of TSWE 280 and 300 samples the peak associated with the pyrolysis process is negligible, in contrast to the peak associated with the combustion process. Analysis of the TG-MS results shows m/z signals of 18, 28, 29 and 44, which probably represent H2O, CO and CO2. The gaseous products were generated in two distinct ranges of temperature. H2O, CO and CO2 were produced in the 500 K to 650 K range with maximum yields at approximately 600 K. In the second range of temperature, 650 K to 800 K, only CO2 was produced with maximum yields at approximately 710 K as a main product of combustion process. Analysis of the FTIR shows that the main gaseous products of the combustion process were H2O, CO2, CO and some organics including bonds: C=O (acids, aldehydes and ketones), C=C (alkenes, aromatics), C-O-C (ethers) and C-OH. Lignin mainly contributes hydrocarbons (3000-2800 cm−1), while cellulose is the dominant origin of aldehydes (2860-2770 cm−1) and carboxylic acids (1790-1650 cm−1). Hydrocarbons, aldehydes, ketones and various acids were also generated from hemicellulose (1790-1650 cm−1). In the kinetic analysis, the two-steps first order model (F1F1) was assumed. Activation energy (Ea) values for the first stage (pyrolysis) increased with increasing torrefaction temperature from 93 to 133 kJ/mol, while for the second stage (combustion) it decreased from 146 to 109 kJ/mol for raw willow, as well as torrefied willow at the temperature range of 200-260°C. In the case of samples torrefied at 280 and 300°C, the Ea values of the first and second stage were comparable to Ea of untreated willow and torrefied at 200°C. It was also found that samples torrefied at a higher temperature, had a higher ignition point and also a shorter burning time.

Air nicotine levels in public places in ahmedabad, India: before and after implementation of the smoking ban

Aim:

To compare air nicotine levels in public places in Ahmedabad, India, before (June 2008) and after (January, 2010) the implementation of a comprehensive smoking ban which was introduced in October 2008.

Materials and Methods:

Air nicotine concentrations were measured by sampling of vapor-phase nicotine using passive monitors. In 2008 (baseline), monitors were placed for 5-7 working days in 5 hospitals, 10 restaurants, 5 schools, 5 government buildings, and 10 entertainment venues, of which 6 were hookah bars. In 2010 (follow-up), monitors were placed in 35 similar venues for the same duration.

Results:

Comparison of the overall median nicotine concentration at baseline (2008) (0.06 μg/m³ Interquartile range (IQR): 0.02-0.22) to that of follow-up (2010) (0.03 μg/m³ IQR: 0.00-0.13), reflects a significant decline (% decline = 39.7, P = 0.012) in exposure to second-hand smoke (SHS). The percent change in exposure varied by venue-type. The most significant decrease occurred in hospitals, from 0.04 μg/m³ at baseline to concentrations under the limit of detection at follow-up (%decline = 100, P < 0.001). In entertainment venues, government offices, and restaurants, decreases in SHS exposure also appeared evident. However, in hookah bars, air nicotine levels appeared to increase (P = 0.160).

Conclusion:

Overall, SHS exposure was significantly reduced in public places after the smoke-free legislation came into force. However, nicotine concentrations were still detected in most of the venues indicating imperfect compliance with the comprehensive ban.