Chlorine Compounds Research Articles

Biogas trace compounds impact on high-temperature fuel cells short stack performance

Nowadays the most important issues for commercial SOFC systems are related to their durability and stability of performance both of which are affected by fuel feeding composition. The trace compounds contained in biogenous fuels can interact with SOFC components causing evident drops in performance and severely reducing the lifetime of the entire system. Due to the significant impact on SOFC performance from widely varying fuel inputs, the influence of trace compounds should be investigated in real case studies and practical applications. Anode deactivation and porous blocking electrodes are the main consequences that occur due to the presence of trace compounds impact.This work shows an experimental case study where the anode supported solid oxide fuel cells short stacks are fed with fuels containing trace compounds. These compounds were selected from the biological decomposition of organic matters. In addition, sulphur compounds were selected chlorine, aromatic compounds, terpenes, and carboxyl compounds were selected. The most deleterious impact on the stack was due to the sulphur action. However, chlorine compounds also affected the external part of the cell causing the stack to break due to the corrosion of the sealant.

Emission reduction process for the energetic use of biogenic residues

During the combustion of biogenic residues particulate matter, nitrogen oxides, chlorine and sulphur compounds as well as dioxins and furans occur in elevated concentrations depending on the respective fuel composition. Corresponding abatement technology is only available for the power plant sector and cannot be used economically on small biomass plants. Therefore an exhaust gas purification procedure was developed and tested which can be used economically in decentral biomass plants. The core of the exhaust aftertreatment process is a fabric filter with catalytically active filter bags which enables a combined reduction of dust and nitrogen oxides. An additional precoating of the fabric filter also removes acidic exhaust gas components such as SO2 and HCl. Experiments were conducted on pilot and field scale. Significant reduction of particle emissions, nitrogen oxides and chlorine compounds could be achieved. Further optimization of the quantities of reducing agent and precoat material supplied is necessary in order to improve the performance of the exhaust gas cleaning process.

Study of Burning Behaviors and Fire Risk of Flame Retardant Plywood by Cone Calorimeter and TG Test

A flame retardant composition was prepared by using phosphoguanidine, guanidine sulfamate, disodium octaborate tetrahydrate and dodecyl dimethyl benzyl ammonium chloride. Veneers were immersed in such flame retardant mixture to prepare plywood. The combustion characteristics and thermal stability of plywood were assessed using a cone calorimeter and TG. Results showed that: (1) High concentration and loading of flame retardant were beneficial for the fire resistance of the plywood. (2) The limiting oxygen index (LOI) and residual mass of plywood processed using the flame retardant was increased by 87.52% and 58.66% compared to those of the untreated plywood, while the average heat release rate (av-HRR), total heat release (THR), effective heat of combustion (EHC), total smoke release (TSR), CO yield (COY), CO2 yield (CO2Y) and oxygen consumption were decreased by 44.3%, 82.9%, 47.0%, 86.0%, 89.9%, 50.1% and 83.1%, respectively. (3) Treated plywood which had a low fire growth index (FGI) displayed a later combustion heat release rate peak and slower flame spread than observed for the untreated material. Combustion of treated plywood displayed a higher fire performance index (FPI), indicating a longer time to ignition. This suggests that burning structures from this material would be subject to a longer time for escape from the structure and would present lower fire risk than similar structures containing treated plywood. (4) TG results demonstrated that the presence of the flame retardant can decrease the pyrolysis temperature for hemicellulose and cellulose, change the decomposition and reaction progress for plywood degradation and promote dehydration carbonization and accelerated charformation. Moreover, the formed char was more stable than that combustion of untreated plywood. (5) The flame retardant contains nitrogen (N), phosphorus (P), boron (B), chlorine (Cl) and guanidine (Gu) compounds. The adhesive also contains N and P compounds. These substances display flame resistance and supplement each other to generate flame retardance than any one used alone. By changing the thermolysis and thermal decomposition processes, the heat release and smoke release from plywood, undergoing combustion was reduced. This controlled generation of combustible substances and promoted dehydration and carbonization to form char. As a result, the flame resistance of plywood was improved significantly. The probability of smoke asphyxia or poisoning death of those trapped in structures containing treated plywood during fire accidents can be decreased dramatically.

Recent advances in the synthesis of organic chloramines and their insights into health care

Organic nitrogen–chlorine compounds and their derivatives are important heterocyclic motifs, exhibiting applications such as N-chlorinating agents, analytical reagents, disinfectants, antipathogens, and as synthetic intermediates for drugs, polymers, and natural products.

Система контроля химических реагентов, применяемых в ПАО «Татнефть», на содержание органического хлора

Система контроля химических реагентов, применяемых в ПАО «Татнефть», на содержание органического хлора

Catalytic processing of organochlorine wastes into valuable monomers

The paper is devoted to experimental development of method for 1,1,2-trichlorethane (TCE) dehydrochlorination (DHC). The economic and environmental issues of organic chlorinated compounds processing are described. The basic principle and possible products of TCE processing are presented. The DHC of TCE, which is one of the chlorinated organic wastes produced in the ethylene dichloride process, to vinylidene chloride (VDC) was carried out over over CaO, MgO supported on SiO2 and modified with CsCl catalysts. This process was carried out in a continuous flow fixed-bed reactor. The prepared catalysts were characterized by surface area and base properties before/after reaction. The methodology for determining properties of catalyst is described. Laboratory activity test apparatus was developed, and the schematic diagram is presented in the paper. The method of determination of TCE concentration of was calculated from its partial saturation vapor pressure at a given temperature is presented. Encouraging results were obtained on the catalyst containing 10 % CsCl/CaO·SiO2. The direction of the DHC reaction changed radically under described conditions: VDC was not formed at all and the major products were cis- and trans-1,2-dichloroethene. Interesting results were obtained with the catalytic system comprising 10 % (MgO-CsCl) (1:1) supported on SiO2. DHC of 2 % TCE/Ar at 302 °C proceeds quantitatively over 20 h with selectivity for VDC of more than 80%. These systems are suitable to study the factors providing the binding and removal of HCl from the reaction zone. A possible way to increase the selectivity for VDC is the creation of the conditions favoring the DHC of TCE into VDC by the radical mechanism, which was observed in experiments with 10% CsCl/CaSiO3. The directions for future researches are formulated and described.

Can Medical-Grade Gloves Provide Protection after Repeated Disinfection?

The advent of the COVID-19 pandemic has generated an increased consumption of personal protective equipment (PPE), including gloves and masks, by healthcare workers and by the general public at a global scale. This has generated substantial shortage of these single-use and disposable PPEs that will end up as a landfill waste. Extending the life cycle of PPEs, such as gloves, by disinfecting treatments could help mitigate these concerns. However, the effect of various disinfection treatments on the functionality of gloves is unknown. In this study, six commonly used viral disinfection treatment methods (i.e., ultraviolet (UV) radiation, dry heat, steam, alcohol, chlorine compounds, and quaternary ammonium compounds) were evaluated for their effect on the performance attributes of two commonly used medical-grade gloves and nitrile and vinyl (latex) gloves. The barrier properties of both gloves against water and ethanol vapor flux were not affected up to 10 cycles of disinfection cycles. However, the increase in the disinfection cycle from 10 to 20 slightly reduced their barrier properties with minor variation in the type of disinfection and glove type. Infrared spectroscopy and microscopy investigations confirmed that both types of gloves could withstand up to 20 cycles of disinfection treatments with no observable change in the chemical structure and surface morphology of the disinfected surfaces, respectively. Lastly, tear property testing of the gloves indicated little to no change from the baseline after 20 cycles of treatment in both the nitrile and vinyl-based gloves. Overall, this study indicated that alcohol, UV, and heat treatment could be acceptable disinfection methods that allow the reuse of gloves up to 20 cycles. Such repeated disinfection of gloves not only reduces the strain on the supply of gloves but also decreases the postconsumer landfilled waste and environmental footprint of gloves.

Validation of SMILES HCl profiles over a wide range from the stratosphere to the lower thermosphere

Abstract. Hydrogen chloride (HCl) is the most abundant (more than 95 %) among inorganic chlorine compounds Cly in the upper stratosphere. The HCl molecule is observed to obtain long-term quantitative estimations of the total budget of the stratospheric chlorine compounds. In this study, we provided HCl vertical profiles at altitudes of 16–100 km using the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) from space. The HCl vertical profile from the upper troposphere to the lower thermosphere is reported for the first time from SMILES observations; the data quality is quantified by comparison with other measurements and via theoretical error analysis. We used the SMILES level-2 research product version 3.0.0. The period of the SMILES HCl observation was from 12 October 2009 to 21 April 2010, and the latitude coverage was 40∘ S–65∘ N. The average HCl vertical profile showed an increase with altitude up to the stratopause (∼ 45 km), approximately constant values between the stratopause and the upper mesosphere (∼ 80 km), and a decrease from the mesopause to the lower thermosphere (∼ 100 km). This behavior was observed in all latitude regions and reproduced by the Whole Atmosphere Community Climate Model in the specified dynamics configuration (SD-WACCM). We compared the SMILES HCl vertical profiles in the stratosphere and lower mesosphere with HCl profiles from Microwave Limb Sounder (MLS) on the Aura satellite, as well as from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) on SCISAT and the TErahertz and submillimeter LImb Sounder (TELIS) (balloon borne). The TELIS observations were performed using the superconductive limb emission technique, as used by SMILES. The globally averaged vertical HCl profiles of SMILES agreed well with those of MLS and ACE-FTS within 0.25 and 0.2 ppbv between 20 and 40 km (within 10 % between 30 and 40 km; there is a larger discrepancy below 30 km), respectively. The SMILES HCl concentration was smaller than those of MLS and ACE-FTS as the altitude increased from 40 km, and the difference was approximately 0.4–0.5 ppbv (12 %–15 %) at 50–60 km. The difference between SMILES and TELIS HCl observations was about 0.3 ppbv in the polar winter region between 20 and 34 km, except near 26 km. SMILES HCl error sources that may cause discrepancies with the other observations are investigated by a theoretical error analysis. We calculated errors caused by the uncertainties of spectroscopic parameters, instrument functions, and atmospheric temperature profiles. The Jacobian for the temperature explains the negative bias of the SMILES HCl concentrations at 50–60 km.

Comparison of thermal and chemical enhanced recovery of DNAPL in saturated porous media: 2D tank pumping experiments and two-phase flow modelling

Pumping experiments were performed in a 2D tank in order to estimate the recovery yield of pure heavy chlorinated organic compounds (DNAPL; dense non-aqueous phase liquids) by varying different parameters: permeability of the saturated zone, pumping flow rates, addition of surfactant and heating. Surfactant was added to decrease capillary forces involved in the entrapment of DNAPL in porous media while temperature was increased to reduce DNAPL viscosity (and hence increase its mobility). Chemical enhancement was performed with the addition of Sodium Dodecyl Benzene Sulfonate (SDBS) (at its Critical Micelle Concentration, to avoid DNAPL dissolution) and thermal enhancement was performed at 50 °C (to avoid DNAPL volatilization). The experiments were monitored with photography allowing, on the basis of image interpretation, to convert optical densities (OD) into water saturations (Sw). Image interpretations were compared with modelling results. The two-phase flow modelling was performed with the pressure-pressure formulation using capillary pressure and relative permeability functions based on the van Genuchten–Mualem equations. Measured volumes of DNAPL recovered as well as the displacement of the DNAPL-water interface (radius and height of the cone of depression) are consistent with the modelling results. Furthermore, chemical enhancement results in a significant increase in the recovery rates of DNAPL. The observed improvement in the recovery of DNAPL with chemical enhancement is due to the fact that: (i) the residual saturation inside the cone of depression is lower and (ii) the cone of depression radius and height increase. Thermal enhancement had no beneficial effect on DNAPL recovery rate or yield. This study shows that it is possible to accurately determine water and DNAPL saturations by image interpretation during pumping tests in a 2D tank in the laboratory. For field-scale applications, the two-phase flow model allows to determine remediation yields as well as the volumes of the cone of depression according to the different operating conditions.

Extractable organochlorine (EOCl) and extractable organobromine (EOBr) in GPC-fractionated extracts from high-trophic-level mammals: Species-specific profiles and contributions of legacy organohalogen contaminants

Previous studies have suggested that unidentified compounds constitute a large proportion of extractable organochlorine (EOCl) and extractable organobromine (EOBr) in the crude extracts without fractionation; however, the proportion of unidentified EOX (X = chlorine, bromine) associated with high-/low-molecular-weight compounds is still unknown. In this study, we applied gel permeation chromatography to fractionate extracts from archived liver samples of high-trophic marine and terrestrial mammals (striped dolphins, cats, and raccoon dogs), for which concentrations of legacy organohalogen contaminants (polychlorinated biphenyls, organochlorine pesticides, and polybrominated diphenyl ethers [PBDEs]) had been previously reported. EOX in high- (>1000 g/mol) and low- (≤1000 g/mol) molecular-weight fractions (EOX-H and EOX-L) were determined by neutron activation analysis. Comparison of EOCl and EOBr enabled the characterization among species. Despite small differences in the concentrations and molecular-weight profiles of EOCl among species, the contribution of chlorine in identified compounds to EOCl-L varied from 1.5% (cats) to 79% (striped dolphins). Considerable species-specific variations were observed in the concentrations of EOBr: striped dolphins exhibited significantly greater concentrations of both EOBr-H and EOBr-L than cats and/or raccoon dogs. Moreover, the contribution of bromine in PBDEs to EOBr-L was >50% in two cats, while it was <6% in other specimens. This is the first report on EOBr mass balance in cetaceans and on EOX mass balance in terrestrial mammals living close to humans. These results suggest the need for analysis of unidentified chlorinated compounds in terrestrial mammals and unidentified brominated compounds in marine mammals.

Characterization of hazardous gases evolved from various biomass wastes during biochar production using TGA-MS

The utilization of biomass waste by biochar production seems to be an efficient and environmental friendly way of biomass treating. Biochar is produced from biomass by low temperature pyrolysis (torrefaction). In this work, twelve different biomass wastes generated in the Czech Republic has been characterized by thermogravimetric analysis combined with mass spectrometry (TGA-MS). Most of all published works are focused on TGA-MS analysis of evolved hydrocarbon gases or on analysis of condensed liquids. This work is converting focus mainly on inorganic gases produced during pyrolysis, which can be toxic, explosive or corrosive. There is a few or none published works focused on sulfur or chlorine compounds in evolved gas. Some compounds that could be potentially produced with biomass compositions were not detected at all (e.g. H2S). Furthermore, it has been found that temperatures higher than those commonly used in torrefaction (i.e., 400 °C) are needed to produce compounds like H2. From the obtained results it can be also seen that CO2, NH3, NO2, SOx, Cl2 and HCl are mainly produced and their concentration reaches maximum just at this temperature. It has been proved that biomass, which contains sulfur and chlorine, releases SOx and HCl during torrefaction. Sulfur oxides, ammonia and chlorine compounds are strongly corrosive. The real conditions of pyrolysis on industrial scale can thus be adjusted according to the TGA-MS data. These data can be also used for the selection of a biomass, most suitable for pyrolysis, where almost no gases are generated with corrosive effect on the pyrolyser.

Modeling study of the indirect treatment of phosphate buffered saline in surface air plasma

Phosphate buffered saline (PBS) is a commonly used medium for in vitro experiments in plasma biomedicine; however, the mechanism for changes in PBS in response to plasma treatment is not well understood. Many kinds of reactive species are produced in plasma-activated PBS, but to date only a few of them can be quantified. In this paper, therefore, we aim to develop a fully coupled model for the interaction between surface air plasma and PBS, primarily to quantify its plasma-induced aqueous reactive species, as well as to elucidate their production mechanism. This model consists of a 0D sub-model for the surface plasma in air, and two 1D sub-models: for the PBS, and for the air gap between the plasma and the PBS. Similar models have been reported by our group fwith respect to the plasma treatment of deionized water. Here, by comparison, an additional 24 chlorine compounds, 17 phosphorous species and 123 chemical reactions are incorporated in our model. Our results indicate that the main aqueous reactive species are H2O2aq, O3aq, NO2aq −, NO3aq −, HClOaq, ClO2aq and ClO3aq −. During plasma treatment, the oxidation reduction potential of most reactive species increases within the first 50 s, then remains almost constant. The chemical profile of the plasma-activated PBS is also plotted, from which it can be observed that some reactive oxygen species, such as OHaq, H2O2aq, and O3aq play a crucial role in the production of chlorine compounds such as HClOaq and ClO3aq −.

Concentrations, profiles, emission inventory, and risk assessment of chlorinated benzenes in bottom ash and fly ash of municipal and medical waste incinerators in northern Vietnam.

Concentrations and congener profiles of seven di- to hexachlorinated benzenes (CBzs) were characterized in bottom ash and fly ash samples collected simultaneously from one medical waste incinerator (MEWI) and one municipal waste incinerator (MUWI) in northern Vietnam. Total concentrations of seven CBzs in the fly ash samples ranged from 6.98 to 34.4 (median 19.1) ng g-1 in the MEWI, and ranged from 59.1 to 391 (median 197) ng g-1 in the MUWI. Concentrations of CBzs in the bottom ash samples of the MEWI (median 1.95; range 1.53-5.98 ng g-1) were also lower than those measured in the MUWI samples (median 17.4; range 14.5-42.6 ng g-1). Levels of CBzs in the fly ash samples were significantly higher than concentrations measured in the bottom ash samples, partially indicating the low-temperature catalytic formation of these pollutants in post-combustion zone. In general, higher chlorinated congeners (e.g., hexachlorobenzene, pentachlorobenzene, and 1,2,4,5-tetrachlorobenzene) were more abundant than lower chlorinated compounds. However, compositional profiles of CBzs were different between the ash types and incinerators and even between the same sample types of different sampling days, suggesting that the formation of CBzs in these incinerators is complicated and influenced by many factors. Emission factors and annual emission amounts of CBzs were estimated for the two incinerators by using actually measured data of CBz concentrations in the ash. Daily intake doses and cancer risks of ash-bound CBzs estimated for workers in the two incinerators were generally lower than critical values, but cancer risks caused by other relevant pollutants (e.g., polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and dioxin-related compounds) were not considered.

Effects of a human-based mixture of persistent organic pollutants on the in vivo exposed cerebellum and cerebellar neuronal cultures exposed in vitro

Exposure to persistent organic pollutants (POPs), encompassing chlorinated (Cl), brominated (Br) and perfluoroalkyl acid (PFAA) compounds is associated with adverse neurobehaviour in humans and animals, and is observed to cause adverse effects in nerve cell cultures. Most studies focus on single POPs, whereas studies on effects of complex mixtures are limited. We examined the effects of a mixture of 29 persistent compounds (Cl + Br + PFAA, named Total mixture), as well as 6 sub-mixtures on in vitro exposed rat cerebellar granule neurons (CGNs). Protein expression studies of cerebella from in vivo exposed mice offspring were also conducted. The selection of chemicals for the POP mixture was based on compounds being prominent in food, breast milk or blood from the Scandinavian human population. The Total mixture and sub-mixtures containing PFAAs caused greater toxicity in rat CGNs than the single or combined Cl/Br sub-mixtures, with significant impact on viability from 500x human blood levels. The potencies for these mixtures based on LC50 values were Br + PFAA mixture > Total mixture > Cl + PFAA mixture > PFAA mixture. These mixtures also accelerated induced lipid peroxidation. Protection by the competitive N-methyl-D-aspartate (NMDA) receptor antagonist 3-((R)-2-Carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP) indicated involvement of the NMDA receptor in PFAA and Total mixture-, but not Cl mixture-induced toxicity. Gene-expression studies in rat CGNs using a sub-toxic and marginally toxic concentration ((0.4 nM-5.5 µM) 333x and (1 nM-8.2 µM) 500x human blood levels) of the mixtures, revealed differential expression of genes involved in apoptosis, oxidative stress, neurotransmission and cerebellar development, with more genes affected at the marginally toxic concentration. The two important neurodevelopmental markers Pax6 and Grin2b were downregulated at 500x human blood levels, accompanied by decreases in PAX6 and GluN2B protein levels, in cerebellum of offspring mice from mothers exposed to the Total mixture throughout pregnancy and lactation. In rat CGNs, the glutathione peroxidase gene Prdx6 and the regulatory transmembrane glycoprotein gene Sirpa were highly upregulated at both concentrations. In conclusion, our results support that early-life exposure to mixtures of POPs can cause adverse neurodevelopmental effects.

Chloride-mediated co-formation of 3-monochloropropanediol esters and glycidyl esters in both model vegetable oils and chemical model systems

3-Monochloropropanediol esters (3-MCPDEs) and glycidyl esters (GEs) with high toxicity have drawn global concerns due to their widespread occurrence in refined oils and oil-based foods. The effect mechanisms of organic chlorine compound lindane, inorganic chlorine compounds tetra-n-butylammonium chloride (TBAC) and sodium chloride (NaCl) on the formation of 3-MCPDEs and GEs were investigated in model oils and chemical models at 240 °C. Results showed that 3-MCPDEs contents increased with the addition of lindane and TBAC, whereas, surprisingly, GEs presented the same tendency as the results of 3-MCPDEs. This suggested that although chlorine compounds were not involved in the formation reaction of GEs, they could also promote GEs formation. Chemical model experiments confirmed that the presence of chlorine compounds led to the transformation of GEs to 3-MCPDEs and conversely 3-MCPDEs could also transform to GEs. The latter transformation rate from 3-MCPDEs to GEs was higher than the former, which might account for the fact that chlorine compounds promoted GEs formation. Additionally, it was also observed that solid NaCl did not induce the increase of 3-MCPDEs and GEs levels in chemical models, suggesting that the chlorine in NaCl, different from lindane and TBAC, was not available for 3-MCPDEs formation. The present findings give novel insights into the interactions between 3-MCPDEs and GEs formation mechanisms, which offer the theoretical basis for efficient and simultaneous inhibition of 3-MCPDEs and GEs.

Biodegradation of trichlorobiphenyls and their hydroxylated derivatives by Rhodococcus-strains

A possibility of using a complex approach is considered to explain features of biodestruction of polychlorinated biphenyls (PCBs), which are known to be persistent organic pollutants. The approach comprises the following main stages: (i) chemical modification of chloroarenes by hydroxylation and (ii) bacterial degradation of the hydroxylated derivatives. This approach is applicable to individual trichlorobiphenyls (PCB 29, PCB 30) and to a widespread mixture Trikhlorbifenil (analog of Aroclor 1242 and Delor 103). As bacterial strain destructors, the Rhodococcus-strains (КТ112–7, СН628, P25) were used. It was established that the main metabolites of microbial biodegradation of both polychlorobiphenyls and their hydroxy derivatives are polychloro- and hydroxy(polychloro)benzoic acids, which allows an assumption to be made about possible further biodegradation of these compounds down to the products of the base exchange reaction in a cell: water, carbon dioxide and chlorine compounds. The study discusses the effect that the structure of PCBs congeners causes on the conversion by hydroxylation, on the biodegradation rate of both PCBs and their hydroxy derivatives, and on the metabolite formation levels.

Understanding the regularities of recovering non-ferrous and rare earth metals from standard test solutions by flotation and solvent sublation

This paper describes the results of experimental and theoretical studies that looked at ion exchange processes in liquid phase systems containing nonferrous metals, rare earth elements and a surfactant — i.e. sodium dodecylsulphate (NaDS). Ion flotation processes are considered in reciprocal systems containing Co+2 and Ni+2. There is a number of reasons for choosing the above salts: – The problem of removing cations of heavy metals (in particular, Co+2 and Ni+2) from water is of relevance; – At рН 7, these ions do not form hydroxides or hydroxide residue; – Co+2 and Ni+2 bond with NaDS to form easily soluble salts; – Quite a few low-cost analysis techniques are known that can detect these ions. Ion flotation processes were also examined in systems containing rare earth elements, NaCl and surfactants. The influence of Cl– ions on the distribution coefficient in Sm+3 and Eu+3 containing systems was studied by comparing instability constants typical of chlorine compounds and hydroxides. It was found that a rising concentration of NaCl is associated with a rising pH of cations of the rare earth elements of interest at the early stage of recovery and during the peak recovery. The paper considers an innovative technique to examine systems with rare earth elements and surfactants — i.e. solvent sublation. The authors examine the possibility of recovering ions of lanthanides (e.g. erbium) by solvent sublation using NaDS as a collector and isooctyl alcohol as an extractant. Many researchers believe the latter to be the best agent for such studies. The concentration of Er+3 in the standard test solutions was 0.001 mol/l. As the process develops, the concentration of extracted ions asymptotically approaches the value that is typical of a system approaching its steady state. It was established that in these conditions the maximum recovery for Er+3 is reached at рН of 8.0. This research study was funded through a scholarship granted by the President of the Russian Federation to young researchers and postgraduate students under the following project: SP-347.2019.1 “Ion flotation as an innovative and efficient technique to recover rare earth elements while concentrating dilute industrial solutions with possible identification of elements”.

Azeotropic Separation of HCl-Water by Pressure Swing Distillation: Steady State Simulation and Economic Optimization

Copper-Chlorine (Cu-Cl) thermochemical cycle for hydrogen production involves decomposition of water into hydrogen and oxygen with the use of intermediate copper and chlorine compounds and all other reactants are regenerated and recycled to create a closed loop. Our ongoing investigations on copper-chlorine (Cu-Cl) cycle involve electrochemical and thermal reactions constituting six steps. Hydrolysis of cupric chloride to copper oxide and dry hydrogen chloride (HCl) gas is one of the crucial steps. This involves non-catalytic reaction of cupric chloride and steam between 350 and 400oC which needs excess steam for complete conversion of cupric chloride thereby resulting formation of dilute hydrochloric acid rather than dry HCl gas which needs to be recycled to hydrogen generation. Therefore, azeotrope between the HCl and water needs to be eliminated. This work has proposed design and optimization of pressure swing distillation (PSD) for separation of HCl -water by using heat integration of two columns operating at different pressures and temperatures. The first column operating at low pressure concentrates the feed up to the azeotropic point and second column operating at high pressure eliminates the azeotrope and generates dry HCl gas. The reboiler heat of high pressure column (HPC) is reutilized to heat the low pressure column (LPC) and HPC feed which reduces the total annual cost (TAC). Heat integration saves an energy cost by 11.03% of and total annual cost by 6.83 % as compared to non-heat integrated PSD system. Feed composition has strong impact on energy and ultimately economics.

Release of nitrogen, sulfur and chlorine species from coal in carbon dioxide atmosphere

In oxyfuel combustion, the release of minority species, such as sulfur, nitrogen and chlorine compounds from the fuel plays an essential role, since significant corrosion and emission issues arise from these species. In the present study, the release of nitrogen, sulfur and chlorine species from a US-American bituminous coal with high sulfur content was studied in CO2 atmosphere in an entrained flow reactor. With the entrained flow reactor, particle heating rates comparable to those observed in a full-scale furnace can be achieved. The experiments were performed at different reactor temperatures in CO2 atmosphere. Gas samples were extracted from the reactor, and the concentration of various gas species, including NO, N2O, NH3, HCN, H2S, SO2, COS and HCl, was determined. It was found that the formation and release of the considered minority species changes with temperature and fuel residence time. A rapid decrease of the N2O concentration and an increase of the NO concentration was observed with increasing temperature. The release of NH3 from the fuel increased with increasing temperature, whereas the release of HCN decreased. Furthermore, compared to pyrolysis in nitrogen atmosphere, the release of sulfur and chlorine species increased significantly. Finally, COS was detected in significant amounts in CO2 atmosphere, but not in inert N2 atmosphere.

Pilot Test on Pre-Swim Hygiene as a Factor Limiting Trihalomethane Precursors in Pool Water by Reducing Organic Matter in an Operational Facility.

Pool water must be constantly disinfected. Chlorine compounds used to disinfect pools react with organic substances such as sweat, urine, and personal care products introduced into pool water by users and results in the formation of disinfection byproducts. Trihalomethanes (THM), including chloroform and dissolved organic carbon (DOC) concentrations, were quantified using a two-stage process: determining initial THM and chloroform levels; then searching for a cheap and easy-to-use method to improve water quality. The method proposed here to limit THM and DOC concentrations in water is controlled showering. At three swimming pool facilities, chloroform concentrations (13.8 ± 0.33 µg/L, 15.5 ± 0.44 µg/L, and 13.9 ± 0.06 µg/L) were below the threshold concentration of 30 μg/L. At a fourth facility, however, the chloroform concentration exceeded that threshold (40.7 ± 9.68 μg/L) when showering was not controlled. Those conditions improved after the introduction of a mandatory shower; concentrations of DOC, THMs, and chloroform all decreased. The chloroform concentration decreased to 29.4 ± 3.8 μg/L, the THM concentration was 31.3 ± 3.9 μg/L, and the DOC concentration was 6.09 ± 0.05 mg/L. Pilot tests were carried out at real facilities to determine whether the control of pre-swim hygiene was possible. The introduction of proper pre-swim hygiene limited the concentration of DOC in water and can lead to a healthier environment for everyone attending the swimming facility.