Hydrogen Chloride Gas Research Articles

Ultralong Phosphorescence from Organic Ionic Crystals under Ambient Conditions

AbstractA new type of materials, organic salts in the crystal state, have ultralong organic phosphorescence (UOP) under ambient conditions. The change of cations (NH4+, Na+, or K+) in these phosphors gives access to tunable UOP colors ranging from sky blue to yellow green, along with ultralong emission lifetimes of over 504 ms. Single‐crystal analysis reveals that unique ionic bonding can promote an ordered arrangement of organic salts in crystal state, which then can facilitate molecular aggregation for UOP generation. Additionally, reversible ultralong phosphorescence can be realized through the alternative employment of fuming gases (ammonia and hydrogen chloride), demonstrating its potential as a candidate for visual ammonic or hydrogen chloride gas sensing. The results provide an environmental responsible and practicable synthetic approach to expanding the scope of ultralong organic phosphorescent materials as well as their applications.

Study on the thermal decomposition of aluminium chloride hexahydrate

ABSTRACTThis paper presents a preliminary study on the thermal decomposition process of aluminium chloride hexahydrate (AlCl3·6H2O) crystal with non-isothermal thermal kinetic analysis and static calcination experiments. The ‘kinetic triplets’ including activation energy, pre-exponential factor and mechanism function for the decomposition reaction were determined through thermal analysis from Differential Scanning Calorimetry–Thermos Gravimetric Analysis results. It is found that the average activation energy and pre-exponential factor were 59.668 kJ mol−1 and 6.67 × 105 min−1, respectively, and the most suitable conversion function was . The emission rates of the gaseous products, water (H2O) and hydrogen chloride (HCl), were calculated from the chlorine content evolution obtained from the static calcination tests, respectively. The phase transformation and the change of particle morphology during the decomposition process were also investigated through X-ray diffraction and scanning electron microscope technologies.

Hydrogen Chloride Release From Combustion of Corn Straw in a Fixed Bed

Chlorine plays an important role in the slagging and corrosion of boilers that burn high-chlorine content biomass. This research investigated the emissions of hydrogen chloride (HCl) gas from combustion of biomass in a fixed bed, as functions of the mass air flow rate through the bed and of the moisture content of the fuel. The biomass burned was corn straw, either raw or torrefied. Results showed that increasing the air flow rate through the bed increased the release of HCl gas, as a result of enhanced combustion intensity and associated enhanced heat release rates. When the airflow through the bed was increased by a factor of six, the amount of fuel-bound chlorine converted to HCl nearly tripled. Upon completion of combustion, most of the chlorine remained in the biomass ashes, with the exception of the highest air flow case where the fraction of chlorine released in HCl equaled that captured in the ashes. HCl emissions from torrefied biomass were found to be lower than those from raw biomass. Finally, drying the biomass proved to be beneficial in drastically curtailing the generation of HCl gas.

Experimental evaporation of hyperacid brines: Effects on chemical composition and chlorine isotope fractionation

Hyperacid brines from active volcanic lakes are some of the chemically most complex aqueous solutions on Earth. Their compositions provide valuable insights into processes of elemental transfer from a magma body to the surface and interactions with solid rocks and the atmosphere. This paper describes changes in chemical and δ37Cl signatures observed in a 1750 h isothermal evaporation experiment on hyperacid (pH 0.1) sulphate-chloride brine water from the active lake of Kawah Ijen volcano (Indonesia). Although gypsum was the only evaporite mineral identified in the evolving brine, decreasing Si concentrations may ultimately result in amorphous silica precipitation. Geochemical simulations predict the additional formation of elemental sulphur at lower water activities (aH2O ≤ 0.65) that were not reached in the experiment. Absence of other sulphates and halides despite the high load of dissolved elements (initial TDS ca. 100 g/kg) can be attributed to increased solubility of metals, promoted by extensive formation of complexes between the variety of cations and the major anions (HSO4−, Cl−, F−) present. Chlorine deviations from a conservative behaviour point to losses of gaseous hydrogen chloride (HCl(g)) and consequently an increase in Br/Cl ratios.Chlorine isotope fractionation that accompanied the escape of HCl(g) showed a marked change in sign and magnitude in the course of progressive evaporation of the brine. The calculated factor of fractionation between HCl(g) and dissolved Cl for the initial interval (before 500 h) is positive (1000lnαHCl(g)-Cldiss.=+1.55±0.49‰to+3.37±1.11‰), indicating that, at first, the escaping HCl(g) was isotopically heavier than the dissolved Cl remaining in the brine. Conversely, fractionation shifted to the opposite direction in the subsequent interval (1000lnαHCl(g)-Cldiss.=5.67±0.17‰to-5.64±0.08‰), in agreement with values reported in literature. It is proposed that Cl isotopic fractionation in highly acidic brines is controlled by the distribution of dissolved chlorine species, which changes from Cl− to HClo dominance with the progressive pH decline.The Kawah Ijen lake acquired its extreme composition through influx of sulphur and halogen-rich magmatic gas components and extensive rock dissolution. If hyperacid brines with comparable chemical composition existed on Mars, evaporation processes up to the extent reported here (aH2O=0.85), were likely accompanied by losses of gaseous HCl. The resulting changes in Cl isotope compositions, Br/Cl, S/Cl and other ratios in the residual brine might be potentially recorded in assemblages of halogen-bearing secondary evaporation minerals. Also, volcanic-hydrothermal brines as these would extend the stability of liquid water on the Martian surface down to a temperature of −90 °C.

Low-Voltage Gaseous HCl Electrolysis with Iron Redox-Mediated Cathode for Chlorine Regeneration

Chlorine (Cl2) is used to synthesize numerous consumer products and useful intermediates.[ 1 ] Chlorination of alkanes or aromatics is a substitution reaction with hydrogen, for which only one chlorine atom is actually used to produce chloro-organics, while the other is lost as gaseous hydrogen chloride (HCl) by-product, which is either disposed as waste gas or recovered as low-value HCl aqueous solution. Today, HCl by-product totals globally 9.3 million tons per year, when only considered is the synthesis of polyurethane, chloromethane, and polycarbonate. At present, only 15% of this HCl by-product is recycled, leaving an unrealized Cl2 regeneration market of $2.4 billion peryear (based on the current price of Cl2: $315/ton).[2] The need to regenerate Cl2 from HCl has become urgent in recent years as the demand for Cl2 is increasing drastically. Conversion from HCl to Cl2 can be achieved via chemical reactions in the Deacon process using a heterogeneous catalyst, but high temperature (e.g., 250–350 oC) and complex reactor design are needed to mitigate intrinsically low reactivity and yield. Alternatively, an electrochemical process can be used that as a simple modular design and mild operating conditions. [3] To complete the electrolysis process, anodic regeneration of Cl2 from HCl must be balanced by a cathodic reaction. There are two major types of cathodes used in HCl electrolysis process: the hydrogen evolution cathode (HEC) (Eqn. 1), and the oxygen reduction cathode, also commonly known as the oxygen depolarized cathode (ODC) (Eqn. 2). HEC-based electrolysis can produce H2as a valuable by-product but ODC-based electrolysis offers significantly lower standard cell voltage due to its high redox potential (1.23 V vs. SHE) HCl → Cl2 + H2 (1) 4HCl → 2Cl2 + 2H2O (2) Herein, we demonstrate a gaseous HCl electrolyzer with Fe3+/Fe2+ redox-mediated cathode (IRC) for the first time to regenerate Cl2. At the anode, gaseous HCl is oxidized to generate chlorine and protons, at the cathode, Fe3+ is electrochemically reduced to form Fe2+. Subsequently, Fe2+ is chemically oxidized to Fe3+ by oxygen in a reactor external to the electrolytic cell. Regeneration Fe2+ is recycled to the electrolyzer. Due to high standard potential (p o, 0.77 VSHE) and fast kinetics (exchange current density, i0 , of ~10−2 A/cm2 on glassy carbon, no catalyst was required),[4] IRC offers substantial benefits over alternative commercial HEC and ODC cathodes. Taking advantage of IRC, a much lower cell voltage is achieved: 0.67 V vs. 1.16 V (with ODC) and 1.22 V (HEC) at a typical current density of 4 kA/cm2. Compared to the commercial HEC or ODC-based HCl electrolysis processes, it will save 45–50% of energy consumption approximately. Moreover, without the need for a precious metal cathode catalyst and a costly thick membrane, the captital cost can be reduced by 40%–50% (IRC: $2,640/m2 vs. HEC: $4,339/m2 and ODC: $5,034/m2, estimated with 4 kA/m2and current materials prices). [1] J. Perez-Ramirez, C. Mondelli, T. Schmidt, et al, Energy & Environmental Science, 2011, 4, 4786. [2] ThyssenKrupp, HCl electrolysis brochure. [3] I. G. Martinez, T. Vidaković-Koch, R. Kuwertz, et al, Electrochimica Acta, 2014, 123, 387. [4] Y. H. Wen, H. M. Zhang, P. Qian, et al, Electrochimica Acta, 2006, 51, 3769.

Multi-Responsive Wrinkling Patterns by the Photoswitchable Supramolecular Network

Multiresponsive reversible wrinkling patterns provide an effective approach to dynamically tuning the properties of surface on-demand to realize a smart surface; however, their fabrication remains challenging. In this study, we report a simple yet robust method to fabricate multiresponsive wrinkles based on a supramolecular polymer network composed of copolymer (P4VP-PS-PnBA) and carboxyl containing anthracene (AN-COOH), which can be cross-linked dynamically through reversible photodimerization of anthracene (AN) and the hydrogen bond between carboxyl and pyridine groups. The wrinkle pattern can be generated and erased selectively by UV radiation of different wavelengths due to reversible dimerization of AN. The resulting wrinkles have an extremely sensitive response to hydrogen chloride (HCl) gas and can be erased by HCl with a concentration of 5 ppm in the atmosphere. The generation/elimination process responsive to light and HCl could be cycled many times without damaging characteristic wrinkles, which...

Fabrication of low-fire-hazard flexible poly (vinyl chloride) via reutilization of heavy metal biosorbents

As a naturally abundant biopolymer, chitosan is considered to be a suitable adsorbent for stannate (SnO32−) in tin plating wastewater. However, mass transfer of the adsorbent and its recycling remain challenging problems. Though flexible poly(vinyl chloride) (PVC) is highly flammable due to the addition of plasticizers, the traditional flame retardant, antimony trioxide (Sb2O3), is potentially harmful. In this study, chitosan was anchored onto the surface of PVC resin to adsorb SnO32− from wastewater. Thereafter, tin-doped chitosan-coated PVC resin was readily recycled and processed into a flexible PVC composite (modified fPVC). The limiting oxygen index value of the modified fPVC increased to 33.1%, and the peak heat release rate decreased to 161kW/m2. In addition to reducing fire hazards, this approach also decreased the content of harmful hydrogen chloride gas released during the combustion of modified fPVC. Meanwhile, the tensile properties of modified fPVC were enhanced compared with those of the Sb2O3-treated sample. These results indicated the synthesis of an eco-friendly Sb2O3-free flexible PVC composite that poses a low fire hazard.

Synthesis of Mono-, Bis- and Tris(pentafluoroethyl)tin Derivatives, (C2 F5 )4-n SnXn (X=Ph, Me, Cl, Br, Cp; n=1-3).

For (pentafluoroethyl)phenylstannanes, (C2 F5 )4-n SnPhn (n=1-3), and dimethylbis(pentafluoroethyl)stannane, (C2 F5 )2 SnMe2 , a high yield synthesis was developed by the use of LiC2 F5 as a C2 F5 transfer reagent. The treatment of these products with gaseous hydrogen chloride or hydrogen bromide afforded (C2 F5 )4-n SnXn (X=Cl, Br; n=1-3) in good yields. The (pentafluoroethyl)stannanes were fully characterized by 1 H, 13 C, 19 F and 119 Sn NMR, IR spectroscopy and mass spectrometry. The treatment of the (pentafluoroethyl)tin halides (C2 F5 )4-n SnXn with 1,10-phenanthroline (phen) led to the formation of the corresponding octahedrally coordinated complexes [(C2 F5 )4-n SnXn (phen)], the structures of which were elucidated by X-ray diffraction analyses. The bromostannane (C2 F5 )3 SnBr reacted with sodium cyclopentadienide to give the (η1 -cyclopentadienyl)tris(pentafluoroethyl)stannane, (C2 F5 )3 SnCp, for which single-crystal X-ray diffraction analysis could be performed. The coupling constants 1 J(119 Sn,13 C) and 2 J(119 Sn,19 F) of all new stannanes are strongly correlated and sensitive to the substitution pattern at the tin atom. For both coupling constants a negative sign could be assigned.

Surface-Catalyzed Reaction between the Gases Hydrogen Chloride and Isoprene

Mixtures of gaseous hydrogen chloride (38–150 Torr) and isoprene (38–80 Torr) were allowed to react in Pyrex IR cells equipped with sodium chloride windows. The disappearance of reactants to form, initially, 3-chloro-3-methyl-1-butene and 1-chloro-3-methyl-2-butene was monitored and subsequent formation of multimeric products, some of which were brown, were observed. Such products may contribute to the formation of, or be found on, atmospheric particles.

Studies on process development for the separation of sodium chloride from residue after evaporation of reverse osmosis reject solution

Abstract The membrane reject streams generated in industrial waste stream are evaporated in solar evaporation pan/multiple effect evaporator. The residue after evaporation (RAE) from reverse osmosis reject streams lacks reusable characteristics, due to a high contamination of inorganic and organic salts. In this investigation, a process was developed to separate sodium chloride from the RAE by selective ion precipitation using hydrogen chloride gas. The possible ways of hydrogen chloride gas was evaluated and used for the precipitation of sodium chloride. The optimized process parameters for the separation of sodium chloride were as follows: hydrogen chloride gas purging time, 3 min; pH, 8.0; temperature, 30 °C; concentration of RAE, 60% (w/v) and H/D ratio, 2.23 for the 100 mL working volume. The RAE and the recovered sodium chloride were characterised, for SEM, XRD and Cyclic voltametry to identify the structural and composition of the material. The results confirmed that the recovered salt is NaCl. The cost toward the disposal of this RAE was also analyzed against present process.

UV–Vis spectra and structure of acid-base forms of dimethylamino- and aminoazobenzene

The changes in the UV–Vis absorption spectra of dimethylaminoazobenzene (DAB) in the cellulose triacetate (CTA) matrix during the absorption of gaseous hydrogen chloride and protonation of DAB in weakly and strongly acid solutions of hydrochloric and sulfuric acids were studied. The yellow-orange color of DAB and its analog aminoazobenzene (AAB) was shown to be due to the dimers, whose structure involves phenylaminyl type cations formed due to the promotion of the sp 2 electrons of the azo groups to the Rydberg R 3s orbitals of the azo groups and possessing Vis bands at 400–417 nm. The cations exist immanently as the dimers due to the Rydberg intermonomer bonds; the Vis bands of the dimers shifted toward 500–520 nm under the action of HCl (in CTA) and weakly acid media as a result of the formation of phenyl aminyl type pair cations, whose π* levels are split by Simpson’s mechanism, during the protonation of interrelated monomers. In the concentrated sulfuric acid, the Vis bands at 500–520 nm vanished because of the decomposition of the dimers into diprotonated monomers possessing Vis bands at 400–417 nm. The mechanism of transformations of chromogens responsible for the spectral transformation was given.

RESEARCH OF FACTORS INFLUENCING THE BURNOUT QUALITY INSIDE A BIOMASS COMBUSTION CHAMBER

The essence of the research is to evaluate how the emission concentrations are influenced by structural elements of combustion chambers, such as the inner walls of combustion chambers, as well as the position of the secondary air channel. For purposes of this research the most common type of combustion chamber structure was selected – combustion chamber of primary and secondary air channel system. A wide variety of gaseous compounds (such as carbon monoxide (CO), carbon dioxide (CO 2 ), nitrogen dioxides (NO x ), sulphur dioxide (SO 2 ), ammonia (NH 3 ), hydrogen chloride (HCl), hydrogen fluoride (HF), formaldehyde (HCHO), methane (CH 4 ) and other unburned hydrocarbons (C x H y )) was measured using an FTIR spectrometer. Other subjects measures obtained were particulate matter (PM ) , temperature inside the combustion chamber, smoke flue draught, etc., including chemical composition of the fuel. It was determined, that the burnout quality of the combustion chamber was influenced both by combustion chamber walls of different thermal conductivity and by position of the secondary air intake. It was determined, that use of vermiculite of lower thermal conductivity (V1) reduced the CO concentration by approximately 30 %, and the general concentration of all volatile organic compounds ( C x H y ) was reduced by half, also resulting in increase of temperature inside the combustion chamber by 33 °C and a 25 % increase of nitrogen oxides (NO x ). It was also determined that the height ratio of the combustion chamber and the secondary air intake of 2.3 (X/H2) is the most suitable position for the secondary air intake. This position ensures a carbon monoxide (CO) concentration is 25 % lower than in other positions, and the concentration of all volatile organic compounds ( C x H y ) is 34 % lower than at height ration of 2.7 (X/H1), and even 44 % lower than at height ratio of 2. DOI: http://dx.doi.org/10.5755/j01.mech.23.1.13960

Filtration of chlorine and hydrogen chloride gas by engineered UiO-66-NH2 metal-organic framework

Chlorine (Cl2) and hydrogen chloride (HCl) are heavily utilized industrial chemicals that present significant respiratory health risks. The metal-organic framework UiO-66-NH2 has shown an unprecedented ability in powder form to remove chlorine gas. Here, we engineered UiO-66-NH2 into 20×40 mesh granules and evaluated their ability to remove chlorine and hydrogen chloride gas challenges. The exposed materials were characterized with nitrogen isotherms, powder X-ray diffraction, and attenuated total reflectance – Fourier transform infrared spectroscopy. Breakthrough results revealed that UiO-66-NH2 sorption of chlorine and hydrogen chloride met or exceeded sorption of state-of-the-art metal-impregnated activated carbon materials on a mass and volume basis in engineered form.

Determination of Ammonium in Aqueous Samples by Gas Phase Light Scattering Using Hydrogen Chloride Gas as a Derivatizing Reagent Followed by Nondispersive Atomic Fluorescence Spectrometry.

A sensitive method was developed for the determination of ammonium in an aqueous solution based on gas phase light scattering. In a stream of carrier gas, the gaseous ammonia from the alkalized solution formed a volatile ammonium chloride derivative by reacting with gaseous hydrogen chloride; the gaseous ammonium chloride was analyzed by nondispersive atomic fluorescence spectrometry. The mechanisms of the method are elucidated based on evaporative light scattering detection. Parameters such as temperature, amount of sodium hydroxide, and carrier gas flow rate were studied. Under optimal conditions, the detection limit of ammonium-nitrogen was 0.045 μg. The method was successfully applied to the determination of ammonium in certified reference materials, and tap and seawater samples.

Preparation of HCl Gas Sorbent from Paper Sludge

Paper sludge (PS) is generated as an industrial waste during the manufacture of recycled paper products, and amounts discharged globally are increasing annually. On the other hands, hydrogen chloride (HCl) is an acidic pollutant that is present in the flue gases of most municipal and hazardous waste incinerators. In this study, the removal of hydrogen chloride gas using the product from paper sludge at high temperatures (700oC) using a fixed-bed flow-type reactor was investigated. PS can be granulated with distilled water using granulators, and the particle shapes can be kept after calcination and alkali reaction. Calcined PS and the product after alkali reaction of calcined PS have amorphous phases and katoite (Ca3Al2(SiO4)(OH)8) phase, respectively, and both of these indicate HCl removal ability at high temperature (700oC). The product from calcined PS via alkali reaction has higher HCl fixation ability (78 mg/g) than calcined PS. Removal experiments for HCl gas showed that the removal process followed pseudo-second-order kinetics rather than pseudo-first-order kinetics. These results suggested that the product particles with HCl gas removal ability at high temperature can be prepared from PS using calcination and alkali reaction.

Iodine Redox-Mediated Electrolysis for Energy-Efficient Chlorine Regeneration from Gaseous HCl

Hydrogen chloride (HCl) by-product is often produced from chlorine-consuming processes. Traditional electrochemical processes for converting HCl to chlorine (Cl2) are completed by anodic oxidation reaction coupled with cathodic reduction reactions (two major types: hydrogen evolution reaction and oxygen reduction reaction). Herein, a triiodide (I3−)/iodide (I−) redox-mediated cathode is implemented for the first time for converting HCl to Cl2. The iodide (I−) can be converted back to triiodide (I3−) by air in a reactor external to the eletrolyzer. The desirable redox potential and facile kinetics of I3−/I− offer a substantially lower operational cell voltage, reducing energy consumption by 20%–25% at a typical current density of 4 kA m−2 and improving the efficiency of Cl2 recovery.

Reaction and transport effects in the heterogeneous systems for lean gas purification

Sorption of hydrogen chloride gas by active soda and that of hydrogen sulfide gas by calcium oxide are explored by experiment as promising means of removing these detrimental contaminants from fuel gas: active Na2CO3 was prepared by the calcination of commercial NaHCO3 at 200 °C; reactive CaO was formed by decomposing a fine-grained, high-calcium limestone at 830 °C. Techniques with a differential reactor were employed to explore the rate of reaction of HCl with Na2CO3 at 500 °C and that of H2S with CaO at 800 °C. Time-resolved data on the sorbents’ conversion were collected as a function of mean particle size in the range between 0.285 and 1.12 mm. The surface reaction constants, deduced via the tractable model from the initial reaction rates of the two reactions, slightly increase with the increasing particle size. The proposed correlations enable to interpolate or cautiously extrapolate to other isotropic, irregularly shaped solids. The effective diffusivities educed by means of the model from the experimental curves decrease significantly with the increasing conversion and are affected by the particle size in both sorptions. The developed reaction rate equations can conveniently be applied to the design and simulation of the deep dechloridization and the bulk desulfurization of hot producer gas.

Synthesis and organic impurity profiling of 4-methoxymethamphetamine hydrochloride and its precursors

4-Methoxymethamphetamine (PMMA) was synthesised from star anise and from 4-methoxytoluene and the organic impurity profiles examined. These two starting materials are unrestricted chemicals in many jurisdictions and contain the requisite functional groups and are thus well suited for clandestine manufacturers. trans-Anethole was extracted from star anise and oxidised to 4-methoxyphenyl-2-propanone (PMP2P). 4-Methoxytoluene was oxidised to anisaldehyde, converted to 4-methoxyphenyl-2-nitropropene, and then reduced to PMP2P. The PMP2P obtained by both methods was then converted to PMMA via the Leuckart reaction. 4-Methoxymethamphetamine hydrochloride (PMMA·HCl) was synthesised from PMMA using hydrogen chloride gas. Both of the examined synthetic methods were found to be feasible routes into PMMA·HCl. The products of each step were analysed by gas chromatography–mass spectrometry (GC–MS) and proton nuclear magnetic resonance spectroscopy (1H NMR). Impurities were examined in an attempt to identify route specific compounds, which may provide valuable information about the synthetic pathway and precursors.

Kinetics of the Removal of Hydrogen Chloride Gas Using Hydroxysodalite at High Temperatures

Kinetics of the Removal of Hydrogen Chloride Gas Using Hydroxysodalite at High Temperatures

Synthesis of Group IV Nanowires on Graphene: The Case of Ge Nanocrawlers.

In recent years, there has been a growing interest in using graphene as a synthesis platform for polymers, zero-dimensional (0D) materials, one-dimensional materials (1D), and two-dimensional (2D) materials. Here, we report the investigation of the growth of germanium nanowires (GeNWs) and germanium nanocrawlers (GeNCs) on single-layer graphene surfaces. GeNWs and GeNCs are synthesized on graphene films by gold nanoparticles catalyzed vapor-liquid-solid growth mechanism. The addition of hydrogen chloride gas (HCl) at the nucleation step increased the propensity toward GeNCs growth on the surface. As the time lag before HCl introduction during the nucleation step increased, a significant change in the number of out-of-plane GeNWs versus in-plane GeNCs was observed. The nucleation temperature and time played a key role in the formation of GeNCs as well. The fraction of GeNCs (χNCs) decreased from 0.95 ± 0.01 to 0.66 ± 0.07 when the temperature was kept at 305 °C for 15 s versus maintained at 305 °C throughout the process, respectively. GeNCs exhibit ⟨112⟩ as the preferred growth direction whereas GeNWs exhibit both ⟨112⟩ and ⟨111⟩ as the preferred growth directions. Finally, our growth model suggests a possible mechanism for the preference of an in-plane GeNC growth on graphene versus GeNW on SiO2. These findings open up unique opportunities for fundamental studies of crystal growth on graphene, as well as enable exploration of new electronic interfaces between group IV materials and graphene, potentially toward designing new geometries for hybrid materials sensors.