Comparison of Domestic and International Technical Standards: Study on Improvement of Quality Control of Halogenated Fire Extinguishing Agents

Recently, the National Fire Protection Association (NFPA) announced the revised standards for halogen compound fire extinguishing facilities (NFPA 2001). Characteristically, it is strengthening the quality control standards for halogenated fire extinguishing agents, by presenting specific standards regarding the effects of not only their main ingredient, but also their additional ingredients on the human body. However, in Korea, halogen compound fire extinguishing agents used for firefighting purposes are managed by designating “purity” as the sole criteria for inspection. Considering that halogen compounds utilized for other purposes in Korea are undergoing quality control through various inspections for the safety of humans and the environment, it is evident that a higher level of quality control is required for halogen compounds used for firefighting purposes. Therefore, we would like to suggest a specific improvement plan to enhance safety while using halogenated fire extinguishing agents, through the comparative analysis of inspection criteria, and acceptance standards of corresponding domestic and foreign standards.

UAS Chromatograph for Atmospheric Trace Species (UCATS) – a versatile instrument for trace gas measurements on airborne platforms

UCATS (the UAS Chromatograph for Atmospheric Trace Species) was designed and built for observations of important atmospheric trace gases from unmanned aircraft systems (UAS) in the upper troposphere and lower stratosphere (UTLS). Initially it measured major chlorofluorocarbons (CFCs) and the stratospheric transport tracers nitrous oxide (N2O) and sulfur hexafluoride (SF6), using gas chromatography with electron capture detection. Compact commercial absorption spectrometers for ozone (O3) and water vapor (H2O) were added to enhance its capabilities on platforms with relatively small payloads. UCATS has since been reconfigured to measure methane (CH4), carbon monoxide (CO), and molecular hydrogen (H2) instead of CFCs and has undergone numerous upgrades to its subsystems. It has served as part of large payloads on stratospheric UAS missions to probe the tropical tropopause region and transport of air into the stratosphere; in piloted aircraft studies of greenhouse gases, transport, and chemistry in the troposphere; and in 2021 is scheduled to return to the study of stratospheric ozone and halogen compounds, one of its original goals. Each deployment brought different challenges, which were largely met or resolved. The design, capabilities, modifications, and some results from UCATS are shown and described here, including changes for future missions.

Macroalgae Microbiomes May Hold the Key to Reducing Methane Emissions From Ruminant Livestock

Ruminant mammals extract nutrients from plant-based food through fermentation in the rumen; fiber and starch are pre-digested by microorganisms and methane is produced as a by-product, which released into the atmosphere acts as a potent greenhouse gas. In an effort to reduce enteric methanogenesis, dietary additives for ruminants have been investigated, and marine macroalgae have proven particularly promising, e.g., the inclusion of 0.2% dry matter of the red alga A. taxiformis into cow feed decreased in vivo methane production by up to 98%. Thus, if globally applied, the addition of algae in ruminant diets could revolutionize the management of greenhouse gas emissions across the livestock sector. However, the ozone-depleting nature of halogen compounds produced in Asparagopsis sp. and the reported adverse health impacts on humans, along with impracticability issues and the difficulty to produce, commercialize and distribute algae widely, has sown some doubt on the feasibility of using macroalgae as methane mitigation instruments. To circumvent such obstacles, and taking into account the paradigm that eukaryotic hosts cannot be understood without considering interactions with their associated microbiome, the exploration of marine algae associated microorganisms is anticipated. Following the notion that in the close and intimate relationships between algae-hosts and their microbiota the origin of chemical response mechanisms is often unclear, and that compounds initially assigned to algae have previously been shown to stem from host-associated microbes, it is not unreasonable to think that these may be involved in the antimethanogenic effects of marine algae in the rumen. Once identified, such microorganisms could lead to antimethanogenic feed additives, and reduce enteric methanogenesis from livestock ruminants substantially. This review is three-fold: it provides a brief, historic overview of macroalgae as feed supplements for ruminants, sums up the difficulties related to using whole-macroalgae as large-scale antimethanogenic feed additives, and describes the macroalga microbiome, including its potential to serve as an antimethanogen for enteric fermentation.

Estimation of Rate Constants for Reactions of Organic Compounds under Atmospheric Conditions

Structure–activity (SAR) methods are presented for estimating rate constants at 298 K and approximate temperature dependences for the reactions of organic compounds with OH, NO3, and Cl radicals and O3, and O(3P) in the lower atmosphere. These are needed for detailed mechanisms for the atmospheric reactions of organic compounds. Base rate constants are assigned for the various types of H-abstraction and addition reactions, with correction factors for substituents around the reaction site and in some cases for rings and molecule structure or size. Rate constant estimates are made for hydrocarbons and a wide variety of oxygenates, organic nitrates, amines, and monosubstituted halogen compounds. Rate constants for most hydrocarbons and monofunctional compounds can be estimated to within ±30%, though predictions are not as good for multifunctional compounds, and predictions for ~15% of the rate constants are off by more than a factor of 2. Estimates are more uncertain in the case of NO3 and O3 reactions. The results serve to demonstrate the capabilities and limitations of empirical methods for predicting rate constants for the full variety of organic compounds that may be of interest. Areas where future work is needed are discussed.

The Role of Catalytic Ozonation Processes on the Elimination of DBPs and Their Precursors in Drinking Water Treatment

Formation of disinfection byproducts (DBPs) in drinking water treatment (DWT) as a result of pathogen removal has always been an issue of special attention in the preparation of safe water. DBPs are formed by the action of oxidant-disinfectant chemicals, mainly chlorine derivatives (chlorine, hypochlorous acid, chloramines, etc.), that react with natural organic matter (NOM), mainly humic substances. DBPs are usually refractory to oxidation, mainly due to the presence of halogen compounds so that advanced oxidation processes (AOPs) are a recommended option to deal with their removal. In this work, the application of catalytic ozonation processes (with and without the simultaneous presence of radiation), moderately recent AOPs, for the removal of humic substances (NOM), also called DBPs precursors, and DBPs themselves is reviewed. First, a short history about the use of disinfectants in DWT, DBPs formation discovery and alternative oxidants used is presented. Then, sections are dedicated to conventional AOPs applied to remove DBPs and their precursors to finalize with the description of principal research achievements found in the literature about application of catalytic ozonation processes. In this sense, aspects such as operating conditions, reactors used, radiation sources applied in their case, kinetics and mechanisms are reviewed.

Effects ofAdding Hydrotalcite with Different Compositional Ratios in the Pyrolysis Treatment of Brominated Plastics

In recent years, chemical recycling technologies related to the pyrolysis of plastics into fuels have received increasing attention under the circular economy agenda with respect to resource depletion. Herein, a method is presented to reduce halogen compounds in the product oil derived from the pyrolysis of polystyrene with tetrabromobisphenol A. Analysis was undertaken to identify the bromine compounds present in the residue after the pyrolysis treatment. Pyrolysis was conducted in the presence of hydrotalcites as a function of the Mg and Al additive composition ratio (type 1; KW-1000 and type 2; K W-2000). The bromine compounds identified in the oil after pyrolysis at 400 °C were determined as 2-bromophenol, 4- bromophenol, 2,4-dibromophenol, 1- bromomethylbenzene, 2- bromomethylbenzene, and 3,6-dibromo-2,5-xylidine. In the absence of hydrotalcite, bromine compounds were still detected in the product oil, residue and gas, whereas the addition of KW-2000 reduced the concentration of bromine compounds in the product oil. The reduced concentration of the bromine compounds in the product oil is suggested to be related to the trapping of bromine by the added hydrotalcite during the pyrolysis of the plastic.