Release Of Chlorine Research Articles

Computer simulation of impacts of a chlorine tanker truck accident

The aim of the study was to present the author’s original modelling programs of pollution dispersion in an urban environment. The programs outlined herein are based on a diagnostic model of air velocity field and Langrangian particle model. In both modelling programs author’s elements of mathematical modelling were applied. The models have been validated and verified. Geographic Information System (GIS) Idrisi Andes was applied in the pre-processing stage.The development of author’s original computer program and stages of hazardous material propagation modelling were discussed.The results of computations and analysis of pollution dispersion caused by a chlorine tanker truck collision and chlorine release into atmosphere were presented. It was simulated that the accident took place in the city of Bielsko-Biała, on a bypass in a built-up area causing leakage of 10t of chlorine. The computer simulations conducted for two wind direction scenarios allow to conclude that the total area affected by the pollutant cloud with concentrations above threshold levels could be over 2km2, with 5000 lethally exposed people.

Synthesis, Characterization, and Photocatalytic Tests of N-Doped Zinc Oxide: A New Interesting Photocatalyst

Fast and simple synthetic methods for the preparation of bare and N-doped zinc oxide, involving a stirring or microwave assisted process, are proposed. All samples were characterized by XRD analysis, BET, and DRS-UV-Vis spectroscopy. The photocatalytic activity of these nanostructured oxides was investigated using phenol and 2,4-dichlorophenol as model molecules under UV-A and visible light irradiation. N-doping in ZnO nanostructures provided a significant increase in phenol and 2,4-dichlorophenol degradation rate under Vis light, leading to a degradation rate higher than that obtained with bare ZnO. The release of chlorine as chloride ions from 2,4-dichlorophenol with N-doped ZnO was faster achieved as well and complete dechlorination was reached within 2 h of irradiation (N-doped ZnO) instead of 3 h (bare ZnO).

Pollution Control of HCl Synthesis Unit in Chloro-Alkali Industry

Control of chlorine gas release is a major concern for most chlor-alkali industries. Normally manual and proportional-derivative-integral control strategies are provided for control. In HCl synthesis plant there are chances of chlorine leakage to atmosphere under certain fault conditions. The limit of chlorine release at stack is 6ppm and its exposure limit at ground is 2ppm. If the chlorine release exceeds the limits it may cause pollution problems and in turn will affect human life and environment. This project defines a control strategy to limit the chlorine gas release from the stack by a control mechanism that measures the chlorine concentration at the stack and control the inlet flow rate of chlorine gas to the oven. For this control mechanism PID, Fuzzy logic and Fuzzy-PID strategies are used and of the three, Fuzzy-PID is the best controller which would efficiently limit the release of chlorine gas to atmosphere

Leaching characteristics of chlorine from municipal solid waste incineration fly ash by up-flow percolation column tests

To determine the potential release of chlorine from municipal solid waste incineration (MSWI) fly ash, the leaching behaviors of MSWI fly ash from Likeng waste incineration power plant in China were characterized according to the US EPA method 1314. Chlorine leaching characteristics were investigated over a wide range of liquid-to-solid ratios (L/S 0.2–10 mL/g-dry) and different pH conditions (2, 4 and 6). The test results revealed that the pH of eluate increased with increasing L/S ratio due to the increased release of CaO in fly ash. An initial fast early chlorine release followed by a slower, final release period was obtained. Chlorine release widely exceeds the limit of 2500 mg/L at initial stage. A maximum extractable amount (43–48 %) was obtained when the cumulative L/S ratio is about 2. The leachability of chlorine was almost pH independent due to the strong solubility. The leaching of chlorine is controlled by solution followed by diffusion of capillary. Exponential decay equation could well fit the cumulative chlorine release curves. X-ray diffraction results showed that the water-soluble chlorides, such as sodium chloride (NaCl), potassium chloride (KCl) and calcium chloride (CaCl2·2H2O), were easy to leach out, while calcium chloride hydroxide [Ca(OH)Cl] was hard to release.

Degradation of 2,4,6-trichlorophenol in aqueous solutions using peroxymonosulfate/activated carbon/UV process via sulfate and hydroxyl radicals

In this study, the activation of peroxymonosulfate (PMS) was investigated by activated carbon (AC) along with UV for 2,4,6-trichlorophenol (TCP) degradation. The effects of operating parameters including pH, PMS concentration, AC dosage, initial TCP concentration and reaction time on TCP degradation were studied and optimized at pH 5.0, 8.0mM PMS, 0.75g/L AC and 75min. Single step or two step additions of PMS made no marked difference in terms of TCP removal. The results of PMS decomposition showed that, AC/UV configuration was able to significantly activate PMS to degrade TCP compared to sole application of AC or UV. The contribution of UV in activation of PMS was more than that of AC. The rate constants of TCP degradation were in range of 0.0103–0.0512min−1 for initial TCP concentrations of 5–50mg/L. Scavenging experiments revealed that sulfate radical was the dominant radical of its kind for degradation of TCP, although hydroxyl radical was also partly effective. The results indicated that contribution of free radicals in solution was higher than that of surface-bound radicals. Moreover, mineralization of TCP was evaluated by COD, TOC and chlorine release and related results were 50.2%, 31.2% and 55%, respectively.

Investigation on K and Cl release and migration in micro-spatial distribution during rice straw pyrolysis

This study investigates the release and migration of potassium (K) and chlorine (Cl) in micro-spatial distribution during rice straw pyrolysis in a lab-scale reactor at temperatures from 300°C to 900°C. The K and Cl enrichment region and the morphology of K- and Cl-rich particles in rice straw and char obtained after pyrolysis was clearly revealed for the first time in this field of research. Scanning Electron Microscope/Energy-Dispersive Spectrometry (SEM/EDS) was used to analyze the morphology and distribution of inorganic matters in raw rice straw and water-washed rice straw, as well as the char obtained from raw rice straw pyrolysis, both upon the epidermis (outside surface) and the ground tissue (internal surface). X-ray Diffraction (XRD) was used to analyze the inorganic matters in the obtained char. The particles dispersedly distributed on the cell walls in the ground tissue were proven to be inorganic salt, rich in K and Cl. The ground tissue rather than the epidermis is the main part that decomposes and loses weight during pyrolysis. K and Cl diffuse from the ground tissue to the epidermis and they might be partly restricted to the epidermis during rice straw pyrolysis. The release of K and Cl is determined by both the mobility of K and Cl and the resistance along the diffusion way inside rice straw.

Release of Inorganic Elements from Gasification and Co-Gasification of Coal with Miscanthus, Straw, and Wood at High Temperature

Three biomass energy feedstocks (wood, straw, and miscanthus) are co-gasified at 1400 °C with two lignites and two hard coals. The objective of this work was to determine the release of alkali metal, chlorine, and sulfur species and to correlate the release with the share of the fuel in the blends. The release of the inorganics is detected using a molecular beam mass spectrometer. Significant species are 34H2S+, 36HCl+, 58NaCl+, 60COS+, and 74KCl+. By comparison of the experimental data with calculations, the influence of the inorganic content of the fuel blends on important release mechanisms and trends is determined. It is shown that the Al/Si ratio and the chlorine content have a major influence on the release of alkali metal species in general. Additionally, it was found that the Al/Si ratio has a strong influence on the release of sulfur species through changes of the availability of Ca.

Experimentally determined distribution of fluorine and chlorine upon hydrous slab melting, and implications for F–Cl cycling through subduction zones

Fluorine and chlorine are volatile elements known to be enriched in primitive arc magmas, and variations of F/Cl ratios can carry information about slab devolatilization processes. Recent experiments on the fractionations of these elements suggest that aqueous fluid has limited capacity to enrich the magma source region in F. Hence, it is difficult to explain observations of primitive arc magmas particularly rich in F. To complement previous experimental studies, we examined the fractionation of fluorine and chlorine during hydrous partial melting of subducting slab. Element-doped phase equilibria experiments were carried out in a complex chemical system at conditions equivalent to potential slab melting temperatures (750–1000°C) across the amphibolite to eclogite facies transition (1.3–3GPa). Partition coefficients of F and Cl between hydrous silicic melts and minerals were determined by electron microprobe and/or ion probe. Fluorine is compatible in amphibole (DFamp/glass=1.18–1.85), and incompatible in garnet (0.034–0.140), clinopyroxene (0.059–0.505), and allanite (0.205–0.504). Hence, amphibole is an important F host, and can retain significant quantities of F in the solid residue of partial melting. On the contrary, Cl is incompatible, with DClmineral/glass generally decreasing from amphibole (0.079–0.625; one outlier at 1.87) to allanite (0.163), clinopyroxene (0.066–0.158), and garnet (0.031–0.153; outlier at 0.492). As a result, Cl is easily mobilized during partial melting. Fluorine and chlorine release during slab melting have been quantified by applying our partition coefficients to a non-modal batch melting model. The model shows that amphibole plays a key role in F/Cl fractionation during partial melting, while F/Cl is close to that of source for the melting of amphibole free eclogite. Moreover, the results from a flux-melting model employing several source compositions are compared to F and Cl abundances in primitive arc magmas. The observed variations are best described by variable additions of slab-derived aqueous fluids and hydrous melts to the mantle wedge melting region.

The real-time estimation of hazardous gas dispersion by the integration of gas detectors, neural network and gas dispersion models

Release of hazardous materials in chemical industries is a major threat to surrounding areas. Current gas dispersion models like PHAST and FLACS, use release velocity, release elevation, meteorological parameters, and other related information as model input. In general, such information is not always available during an on-going accident. In this paper, we develop a fast prediction approach which could bypass the input parameters that are difficult to obtain and predict the released gas concentration at certain off-site location using parameters that could be obtained easily. The new approach is an integration of gas detectors, artificial neural network (ANN) and one of the aforementioned gas dispersion models. PHAST is applied to simulate numbers of release scenarios and the results containing the spatial and temporal distributions of released gas concentration are prepared as input and target data samples for training the neural network. The approach was applied to a case study involving a hypothetical chlorine release with varying release rates and atmospheric conditions. The results of the approach that are concentration and dispersion time profiles in the environmental sensitive locations were validated against PHAST. The validation shows highly correlations with PHAST and convincingly demonstrates the effectiveness of the proposed approach.

Synthesis of 1,4‐Disubstituted Pyrido[1′,2′:1,5]pyrazolo[3,4‐d]pyridazines by Means of SNAr and Palladium‐Catalysed Reactions

AbstractThe first efficient synthesis of various 1,4‐disubstituted pyrido[1′,2′:1,5]pyrazolo[3,4‐d]pyridazines is reported. The reactivity toward chlorine release at the C‐1 and C‐4 positions was investigated. SNAr and palladium‐catalysed cross‐coupling reactions were carried out, and conditions were optimised for each procedure. 1,4‐Bis(het)aryl derivatives were obtained under a Suzuki cross‐coupling procedure whereas SNAr substitution was achieved mainly at C‐1 in preference to C‐4. The monosubstituted C‐4 morpholino derivative was used as a starting material to provide dissymmetrical 1,4‐diaminated or 1‐(het)aryl‐4‐morpholino products.

Ion irradiation of 37Cl implanted nuclear graphite: Effect of the energy deposition on the chlorine behavior and consequences for the mobility of 36Cl in irradiated graphite

Graphite is used in many types of nuclear reactors due to its ability to slow down fast neutrons without capturing them. Whatever the reactor design, the irradiated graphite waste management has to be faced sooner or later regarding the production of long lived or dose determining radioactive species such as 14C, 3H or 36Cl. The first carbon dioxide cooled, graphite moderated nuclear reactors resulted in a huge quantity of irradiated graphite waste for which the management needs a previous assessment of the radioactive inventory and the radionuclide’s location and speciation. As the detection limits of usual spectroscopic methods are generally not adequate to detect the low concentration levels (<1ppm) of the radionuclides, we used an indirect approach based on the implantation of 37Cl, to simulate the presence of 36Cl. Our previous studies show that temperature is one of the main factors to be considered regarding the structural evolution of nuclear graphite and chlorine mobility during reactor operation. However, thermal release of chlorine cannot be solely responsible for the depletion of the 36Cl inventory. We propose in this paper to study the impact of irradiation and its synergetic effects with temperature on chlorine release. Indeed, the collision of the impinging neutrons with the graphite matrix carbon atoms induces mainly ballistic collisions. However, a small part of the recoil carbon atom energy is also transferred to the lattice through electronic excitation. This paper aims at elucidating the effects of the different irradiation regimes (ballistic and electronic) using ion irradiation, on the mobility of implanted 37Cl, taking into account the initial disorder level of the nuclear graphite.

Modeling an irritant gas plume for epidemiologic study

Plume dispersion modeling systems are often used in assessing human exposures to chemical hazards for epidemiologic study. We modeled the 2005 Graniteville, South Carolina, 54,915 kg railcar chlorine release using both the Areal Locations of Hazardous Atmospheres and Hazard Prediction and Assessment Capability (HPAC) plume modeling systems. We estimated the release rate by an engineering analysis combining semi-quantitative observations and fundamental physical principles. The use of regional meteorological conditions was validated by comparing concentration estimates generated by two source-location weather data-sets. The HPAC model estimated a chlorine plume with 20 ppm outdoor concentrations up to 7 km downwind and 0.25 km upwind/downgrade. A comparative analysis of our two models showed that HPAC was the best candidate for use as a model system on which epidemiologic studies could be based after further model validation. Further validation studies are needed before individual exposure estimates can be reliable and the chlorine plume more definitively modeled.

Growth of TixAl1 − xOy films by atomic layer deposition using successive supply of metal precursors

Atomic layer deposition (ALD) of thin ternary films from TiCl4, trimethylaluminum (TMA), AlCl3 and H2O was investigated at different successions of precursor pulses with the aim to explore passivation effect of TiCl4 to the chemisorption of TMA and AlCl3. Concentrations of Ti and Al in the films grown on silicon substrates at 100–500°C in different ALD precursor sequences were studied. In order to obtain additional information about the deposition mechanisms, the behavior of the quartz crystal microbalance (QCM) signal during ALD cycles was characterized and analyzed at a deposition temperature of 200°C. Post-deposition analysis revealed up to 2 times lower Al2O3 deposition rate in the TiCl4-TMA-H2O and TiCl4-AlCl3-H2O processes than that in the TiCl4-H2O-TMA-H2O and TiCl4-H2O-AlCl3-H2O processes, respectively. Despite of the markedly reduced growth rate of Al2O3 in the TiCl4-TMA-H2O and TiCl4-AlCl3-H2O processes, films with Al/(Al+Ti) ratios exceeding 0.5 were obtained. Consequently, the surface intermediate species, which stopped further adsorption of TiCl4, limited the adsorption of AlCl3 and TMA only partially. Enhanced growth rate of TiO2 was observed in films grown in the TiCl4-TMA-H2O and TiCl4-H2O-TMA-H2O processes. QCM revealed more efficient chlorine release and thereby reduced effect of steric hindrance in those processes. In addition, marked increase of Al2O3 deposition rate was observed in the TiCl4-H2O-TMA-H2O and TiCl4-TMA-H2O processes with the increase of deposition temperature from 300°C to higher temperatures. As no increase of this kind was recorded in the TMA-H2O process, the effect was related to the influence of Ti-containing surface layer on the adsorption of TMA.

Effect of temperature and oxygen content on the release of organic and inorganic species during high temperature thermochemical conversion of PVC-condensate

In this study, the release of organic and inorganic species during high-temperature thermochemical conversion of PVC-condensate was determined online by Molecular beam Mass Spectrometry. The lab-scale experiments were conducted at 1000–1400°C with an oxygen content reaching from 0 to 30vol.%. The organic species under investigation were 51C4H3+, 52C4H4+, 53C4H5+, 77C6H5+, and 78C6H6+. The inorganic species under investigation were 36HCl+, 58NaCl+, 39NaO+, 60COS+, and 56Fe+. This investigation showed for the first time that organics can be effectively destroyed even in an oxygen depleted atmosphere at 1400°C. Furthermore, the release of chlorine, sulphur, and alkaline species is shown to be less temperature sensitive than oxygen sensitive in the temperature range of 1000–1400°C.

Accidental Release of Chlorine from a Storage Facility and an On‐Site Emergency Mock Drill: A Case Study

In the current industrial scenario there is a serious need for formulating strategies to handle hazardous substances in the safest way. Manufacture, storage, and use of hazardous substances pose a serious risk to industry, people, and the environment. Accidental release of toxic chemicals can lead to emergencies. An emergency response plan (ERP) is inevitable to minimize the adverse effects of such releases. The on-site emergency plan is an integral component of any process safety and risk management system. This paper deals with an on-site emergency response plan for a chlorine manufacturing industry. It was developed on the basis of a previous study on chlorine release and a full scale mock drill has been conducted for testing the plan. Results indicated that properly trained personnel can effectively handle each level of incidents occurring in the process plant. As an extensive guideline to the district level government authorities for off-site emergency planning, risk zone has also been estimated with reference to a chlorine exposure threshold of 3 ppm.

Effects of Steam on the Release of Potassium, Chlorine, and Sulfur during Char Conversion, Investigated under Dual-Fluidized-Bed Gasification Conditions

The corrosion and fouling of heat-transfer surfaces and the agglomeration of bed materials in fluidized beds are some of the ash-related problems caused by the transformation and release to the gas phase of ash-forming elements from biomass during thermochemical conversion processes. The magnitudes of these problems are largely dependent upon the release of potassium (K), chlorine (Cl), and sulfur (S) from the biomass. We investigated the effects of steam on the release of K, Cl, and S during char conversion, under conditions relevant for dual-fluidized-bed gasification (DFBG). The study was carried out with wheat straw in a laboratory-scale bubbling fluidized-bed reactor in the temperature range of 800–900 °C. The release of K, Cl, and S from wheat straw during devolatilization, char gasification, and char combustion was quantified with a mass balance that linked the masses of these elements in the wheat straw to the mass of the solid residue obtained at the end of each experiment. To facilitate analyses of the experimental results, leaching and the Brunauer–Emmett–Teller surface area measurement of the wheat straw and some of the solid residues were carried out. The results show that, during devolatilization, the release of volatile salts, e.g., KCl, is significantly limited by intraparticle diffusion resistance, owing to a compact char matrix (i.e., negligible porosity). However, during char gasification, steam renders the char less compact by expanding and/or creating new pores in the char. As a result, intraparticle diffusion resistance decreases, thereby facilitating the evaporation of volatile salts of K and S from the char matrix. The conversion of the char is also conducive to the release of char-bound K and S, especially at 900 °C. At temperatures of >800 °C, the relative proportions of the elements released and char gasified indicate that the release of K can somewhat be decoupled from the release of S and Cl by maximizing the extent of char conversion in the gasification chamber. The results also show that, during char combustion, the proportions of the char that can be combusted and the extent of the release of the elements are influenced by the extent to which the char is gasified in the gasification chamber.

Fate of Sulfur, Chlorine, Alkali Metal, and Vanadium Species during High-Temperature Gasification of Canadian Tar Sand Products

Co-feed of alternative fuels, e.g., petcoke, gains increasing importance for energy conversion in not only Germany but also worldwide. An auspicious process for power generation is the integrated gasification combined cycle (IGCC). Several volatile inorganic species are of concern in IGCC power systems, because they can cause erosion, corrosion, fouling, and slagging. The aim of this work was to obtain detailed information on the influence of fuel composition of the refinery product line tar sand, bitumen, and petcoke in comparison to the standard fuel hard coal on the release of sodium, potassium, chlorine, sulfur, and vanadium species during high-temperature gasification. In addition to the pure fuels, blends of hard coal and petcoke were gasified in lab-scale experiments in a helium/oxygen atmosphere at 1500 °C. The atmospheric conditions were in an entrained flow gasifier. Hot gas analysis was performed by molecular beam mass spectrometry. Species of interest were HCl, H2S, COS, SO2, NaCl, KCl, KOH, a...

Hydrothermal carbonization of poly(vinyl chloride)

Poly(vinyl chloride) (PVC) was subjected to hydrothermal carbonization in subcritical water at 180–260°C. Dehydrochlorination increased with increasing reaction temperature. The release of chlorine was almost quantitative above ∼235°C. The fraction of organic carbon (OC) recovered in the hydrochar decreased with increasing operating temperature from 93% at 180°C to 75% at 250°C. A wide array of polycyclic aromatic hydrocarbons (PAHs) could be detected in the aqueous phase, but their combined concentration amounted to only ∼140μgg−1 PVC-substrate at 240°C. A pathway for the formation of cyclic hydrocarbons and O-functionalized organics was proposed. Chlorinated hydrocarbons including chlorophenols could only be identified at trace levels (low ppb). Polychlorinated dibenzodioxins (PCDDs) and dibenzofurans (PCDFs) could not be detected. The sorption potential of the hydrochar turned out to be very low, in particular for polar organic pollutants. Our results provide strong evidence that hydrothermal carbonization of household organic wastes which can be tied to co-discarded PVC-plastic residues is environmentally sound regarding the formation of toxic organic products. Following these findings, hydrothermal treatment of PVC-waste beyond operating temperatures of ∼235°C to allow complete release of organic chlorine should be further pursued.

Release of chlorine from the slow pyrolysis of NaCl-loaded cellulose at low temperatures

This study reports the chlorine (Cl) release during the slow pyrolysis of NaCl-loaded cellulose in the temperature range of 150–400°C, providing new data to better understand the low-temperature Cl release during biomass pyrolysis. The results show that the form and amount of Cl released during the slow pyrolysis of the NaCl-loaded cellulose strongly depend on pyrolysis temperature. Cl is mainly released as HCl (g) at temperatures ⩽300°C whereas it can be released in forms that are organically bound in heavy tar (termed as “tar-Cl”) at temperatures ⩾350°C. The release of both HCl (g) and total Cl (including gaseous HCl and tar-Cl) begins at 200°C, reaches the corresponding maximum values (∼53% for gaseous HCl and ∼71% for total Cl) at 350°C, and then levels off with further increasing temperature to 400°C. The amount of organically bound Cl in solid residues after pyrolysis also increases from ∼6% at 150°C to ∼36% at 300°C, expressed as % of Cl in the solid residues. Further increasing temperature to 350–400°C leads to the depletion of the organically bound Cl in the solid residues. Our data show that the interaction between Cl and cellulose organic structure is at least one of the mechanisms responsible for the release of HCl (g) and tar-Cl during biomass pyrolysis.

An Automated Mitigation Model for Chlorine Release by Proposing Modifications in the Existing Plant Facilities

Chlorine is highly toxic and an accidental release of chlorine has the potential to kill or cause injury to people. This kind of release may occur unexpectedly and cause huge loss. Hence, proper mitigation methods should be devised to tackle them effectively. In this study, an accidental release of liquid chlorine from the storage tank is considered and a new mitigation model for the effects of release is proposed. A provision to recover the leaked chlorine is also proposed in the mitigation system. This approach can be beneficial to understand the significant elements of mitigation system and serve as a reference to various emergency response and design practitioners.