Chlorine Source Research Articles

Influence of Chlorine on the Fate of Pb and Cu during Clinkerization

The fate of heavy metals during clinkerization is of crucial significance to the utilization of solid waste as fuels and raw materials in cement kiln producing clinker. A ternary system of clinker–heavy metal–chlorine was developed that is more coincident with the condition of coprocessing of solid waste in cement kiln. The main goal of this study was to investigate the relationships among chlorine, volatilization and solidification of Cu/Pb, and the mineral phases of the clinker during clinkerization. The AlCl3·6H2O (chlorine source) and PbO/CuO were mixed with cement raw meal in appropriate ratios to produce coprocessed clinkers. The volatilization and solidification of Pb and Cu were investigated experimentally using a combination of atomic absorption spectrometry, electron probe microanalysis, scanning electron microscopy with energy-dispersive X-ray spectroscopy, optical microscope, and thermogravimetric and X-ray diffraction quantitative analyses. The volatilization ratios of Pb and Cu increased up to 46.18% and 34.04%, respectively, with increasing AlCl3·6H2O content up to 1.6% compared to the cement mixtures without AlCl3·6H2O addition (Pb and Cu volatilization ratios are 49.90% and 27.21%, respectively). Pb and Cu oxides can be transformed into Pb and Cu chlorides that are not stable and that have high vapor pressure. Pb and Cu are mainly concentrated in the interstitial phases of the clinker. The addition of AlCl3·6H2O led to the increase of the crystal size of alite and belite. X-ray diffraction quantitative analyses proved that the content of silicate phase increased with the corresponding content of interstitial phases decreasing during clinkerization with the addition of AlCl3·6H2O that decreased the ability of the clinker to solidify Pb and Cu in the produced clinkers. This research can help to promote understanding of the fate of heavy metals during the cement kiln coprocessing of solid wastes and can be meaningful for energy conservation and sustainable development.

Usefulness of Sunlight and Artificial UV Radiation Versus Chlorine for the Inactivation of Cryptosporidium Oocysts: An in Vivo Animal Study.

BACKGROUND:Cryptosporidium is an important waterborne protozoan.AIM:The aim of this study was to investigate the effect of sunlight being the natural source of UV and artificial UV irradiation on Cryptosporidium oocysts versus the effect of chlorination, being the traditional method of water disinfection and to provide an insight into the viability and degree of infectivity of Cryptosporidium oocysts, using an animal model.METHODS:An experimental study including 300 neonatal mice was carried out to investigate the effect of artificial ultraviolet (UV) irradiation and sunlight being the natural source of UV irradiation versus chlorine, the traditionally used water disinfectant on the infectivity of Cryptosporidium oocysts present in water. For each item, nine different exposure times were investigated. Parasitological assessment (Modified Ziehl Neelsen stained stool smears) and histopathological assessment of the excised segments of the small intestine (stained by both Haematoxylin & Eosin and ZN stain) of mice were used to verify the inactivation of oocysts.RESULTS:Cryptosporidium oocysts failed to induce any noticeable infection after 4 hours of artificial UV exposure that provided a UV dose of 10mJ/cm2 and after an 8 hours exposure to sunlight, whereas they showed resistance to disinfection by chlorine.CONCLUSION:The results of the study demonstrate the important role of an 8 hours sunlight exposure of potable water in plastic bottles in achieving complete inactivation of any contaminating Cryptosporidium oocysts, thus offering an applicable, economical and convenient method for the control of cryptosporidiosis especially in developing countries.

Facile synthesis of Ag@AgCl-contained cellulose hydrogels and their application

A cube-like Ag@AgCl-contained cellulose hydrogel was successfully synthesized via a facile two-step method. During the reaction process, the cross-linker of the cellulose hydrogel served as the chlorine source. And the hydrogel network played important role in the control of Ag@AgCl particles morphology. No additional surfactants, templates, reducing agents or special equipment are required during this synthesis procedure. The resulting hydrogel exhibit highly efficient degradation of methyl orange under visible light irradiation due to the photocatalytic property of the contained Ag@AgCl particles. Cycle experiments demonstrated good photocatalytic stability of this hydrogel in repeated use. This study provides a simple approach in fabrication of plasmon photocatalysts which could be reused easily without centrifugation.

Enantioselective α-chlorination of β-keto esters and amides catalyzed by chiral imidodiphosphoric acids

Chiral imidodiphosphoric acids were employed as catalysts for the enantioselective α-chlorination of β-keto esters and amides using NCS as the chlorine source, providing a series of optically active products with good to high enantioselectivities (74–95% ee) and excellent yields (92–99%). This represents the first report of the Brønsted acid catalyzed enantioselective α-chlorination of cyclic β-keto derivatives.

Post-Functionalization of P3HT Via Anodic Oxidation with High Current Efficiency

Recently, post-functionalization has attracted attention as a useful strategy to obtain functional polymers. We have already reported the anodic chlorination of poly(3-hexylthiophene) (P3HT) in the presence of chloride ions under a constant potential condition, and found that introduction of a chlorine atom to the 4-position of the thiophene rings could tune the optoelectronic properties of P3HT. However, the current efficiency of this reaction was low because of the competitive oxidation between P3HT and the chloride ions used as a chlorine source.1 In this study, we improved the current efficiency of the anodic chlorination of P3HT by using boron trifluoride-diethyl ether complex (BFEE). BFEE is well-known to decrease oxidation potentials of aromatic compounds due to the π-complex formation between BF3 and aromatic rings.2 BFEE used as a solvent and an electrolyte in voltammetric studies successfully decreased the oxidation potential of P3HT, and increased the oxidation potential of chloride ions. These interesting effects of BFEE also worked in the macroscale electrolysis of P3HT, giving higher current efficiency compared to the conventional methods.References S. Hayashi, S. Inagi, K. Hosaka, T. Fuchigami, Synth. Met., 2009, 159, 1792.S. Jin, G. Xue, Macromolecules, 1997, 30, 5753. Figure 1

Effects of the addition of municipal solid waste incineration fly ash on the behavior of polychlorinated dibenzo-p-dioxins and furans in the iron ore sintering process

Raw materials were co-sintered with municipal solid waste incineration (MSWI) fly ash through iron ore sintering to promote the safe treatment and utilization of MSWI fly ash. To assess the feasibility of this co-sintering method, in this study, the effects of the addition of MSWI fly ash on the formation and emission of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) were estimated via iron ore sintering pot experiments. During co-sintering, most of the PCDD/Fs in the added MSWI fly ash were decomposed and transformed into PCDD/Fs associated with iron sintering, and the concentrations of lower- and mid-chlorinated congeners increased. As there was a sufficient chlorine source and the sintering bed permeability was decreased by the addition of MSWI fly ash, the PCDD/F concentration in the exhaust gas increased. The mass emission of PCDD/Fs decreased; however, the emission of toxic PCDD/Fs increased beyond the total emissions from the independent MSW incineration and iron ore sintering processes due to the transformation of PCDD/F congeners. The co-sintering may be an important solution after technological improvements in the flue gas cleaning system and PCDD/F formation inhibition procedures.

Fluoroalkylsulfonyl Chlorides Promoted Vicinal Chloro-fluoroalkylthiolation of Alkenes and Alkynes.

The unprecedented use of CF3SO2Cl for direct bifunctional chloro-trifluoromethylthiolation of alkenes and alkynes is reported. CF3SCl, which is generated by the reduction of PPh3, undergoes electrophilic addition and then chlorination to give the bifunctionalized products without using an additional chlorine source. The method is also applicable for chloro-difluoromethylthiolation using CF2HSO2Cl.

Crystallisation of CH 3 NH 3 PbX 3 (X = I, Br, and Cl) trihalide perovskite using PbI 2 and PbCl 2 precursors

In this work, the effects of halides on the properties of mixed-halide perovskite films are investigated. The films were prepared by sequential deposition two-step technique. PbI 2 or PbI 2 -PbCl 2 solution was first spin-coated on fluorine-doped tin oxide glasses, and CH 3 NH 3 (I x Br y ) solution, with different molar ratio of I - and Br - (1:0, 2:1, 4:1, 1:4, 1:2, and 0:1), was subsequently coated on top. Then, the films were annealed at 90°C for 1 h and 100°C for 25 min to transform into perovskite structure. The characterisation of perovskite films included X-ray diffraction, ultraviolet-visible spectroscopy, photoluminescence spectroscopy, and scanning electron microscopy. The results indicated that the incorporation of Br - and/or Cl - in iodine-based perovskites, i.e. CH 3 NH 3 Pb(I 1-x Br x ) 3 and CH 3 NH 3 Pb(I 1-x-y Br x Cl y ) 3 , would enlarge their bandgap. However, with the use of PbI 2 precursor, excess PbI 2 occurred and resulted in minor affects on the structural and optical properties. The use of PbCl 2 as chlorine source was also found to affect the quality of the film morphology. The analysis in this study could provide another insightful aspect for understanding the role of halides in the synthesis of mixed-halide perovskites.

Inhibition of element sulfur and calcium oxide on the formation of PCDD/Fs during co-combustion experiment of municipal solid waste

In order to investigate the effect of element sulfur (S) and calcium oxide (CaO) on the formation of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) during municipal solid waste (MSW) combustion process, MSW was incinerated with S or CaO in a laboratory-scale incinerator and heated in the flow of N2-O2 gas mixture at 800°C. It can be concluded that 25% of oxygen concentration is the best condition for the following inhibitors experiments through a series of oxygen variation experiments. With adding S and CaO in MSW incineration, seventeen kinds of 2, 3, 7, 8-substituted PCDD/Fs congeners were analysed with high-resolution chromatography and mass spectrometry method. The results show that S and CaO obviously suppress PCDD/Fs formation. Comparing inhibition effect of S with that of CaO, the inhibitory effect of S on HpCDD/Fs formation was most remarkable, of around 88.1%; while CaO could inhibit the formation of HxCDD/Fs more evidently than sulfur and the inhibition was 85.1%. PCDFs were the main components of dioxins produced from MSW incineration in the experiments, and S and CaO were unable to change the dominating generation route of PCDD/Fs. S and CaO could mainly consume chlorine sources or weaken the chlorination in the PCDD/Fs formation process to restrain the PCDFs formation, but the inhibition mechanisms were different. In addition, some dioxins or precursors might be decomposed by S and CaO.

Chlorine diffusion in rhyolite under low-H2O conditions

The chlorine diffusivity in rhyolitic melts containing <1.2 wt% H2O was determined at 650 °C–950 °C and 1.5–11.8 MPa. Diffusion experiments were carried out by reacting rhyolitic obsidian with four types of chlorine sources including a pure Cl2 fluid, Cl2 + H2O fluid mixture, molten NaCl, and NaCl aqueous solution. In the pure Cl2 experiments, the chlorine diffusivity ranged from 7.7 × 10−18 m2/s (650 °C) to 8.2 × 10−16 m2/s (950 °C); it is much lower than previously reported values for rhyolitic melt. The Cl2 + H2O fluid mixture experiments revealed that the chlorine diffusivity strongly depends on the water content: it increased by 1–2 orders as the water content of the melt increased to ~1 wt%. In the molten NaCl experiments, sodium infiltrated into the melt while potassium diffused out. The chlorine diffusivity was higher than that in the pure Cl2 experiments by a factor of 4–10. A single experiment using NaCl solution as a chlorine source resulted in the highest Cl diffusivity, probably due to the high H2O and sodium contents. The activation energy of chlorine diffusion was 135–202 kJ/mol, and it is comparable to the activation energy in more mafic melts. Because the diffusivity of chlorine is much smaller than that of H2O and CO2, a strong diffusive fractionation is expected to occur during magma vesiculation and degassing. Calcium diffusion was observed as a by-product of chlorine diffusion under anhydrous conditions. In the pure Cl2 experiments, calcium diffusivity ranged from 6.2 × 10−17 m2/s (650 °C) to 3.9 × 10−14 m2/s (950 °C), and the activation energy was 177 ± 15 kJ/mol. In molten NaCl experiments, the calcium diffusivity was higher by one order of magnitude, and the activation energy was similar to that for the pure Cl2 experiments.

Catalytic decomposition of PCDD/Fs on a V2O5-WO3/nano-TiO2 catalyst: effect of NaCl.

The effect of NaCl addition on the properties, activity, and deactivation of a V2O5-WO3/nano-TiO2 catalyst was investigated during catalytic decomposition of gas-phase polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). The extent of deactivation relates directly to the NaCl loading of the catalyst. Poisoning by sodium neutralizes acid sites, interacts strongly with active VOx species, and reduces the redox capacity of catalysts. In addition, NaCl is also a chlorine source and may actually accelerate the synthesis of new PCDD/Fs. Washing a catalyst with dilute sulfuric acid largely restores catalytic activity, breaking the interaction of Na+ ions and dispersed vanadia and removing Na from the catalyst surface. Consequently, catalyst acidity and redox capacity almost recover. Furthermore, sulfate residues react with surface adsorbed water to generate Brønsted acid sites, ensuing a surge of strong acidity of the catalysts.

Reaction mechanism of organoselenium-catalyzed syn-dichlorination of alkenes: a DFT study.

A new method for the syn-dichlorination of alkenes at room temperature has been proposed by Denmark et al. The method uses diselenide (PhSeSePh) as the precatalyst, benzyltriethylammonium chloride (BnEt3NCl) as the source of chlorine, and an N-fluoropyridinium salt as the oxidant to recover the catalyst. This approach has achieved exquisite diastereocontrol on a number of alkene substrates. In this paper, we report the results of DFT calculations we performed to study the mechanism of this reaction. We were able to identify a reasonable reaction path, including the intermediate and transition-state structures. The results also indicate that PhSeCl3, rather than PhSeCl, is the active catalyst.

A construction of Ag-modified raspberry-like AgCl/Ag2WO4 with excellent visible-light photocatalytic property and stability

A novel multiphase photocatalyst of Ag-modified raspberry-like AgCl/Ag2WO4 composite was successfully fabricated via a facile solvent-free reaction technique, in which the Ag and AgCl were subtlely generated from the one-step reaction between Ag2WO4 particles and HONH3Cl as reductant and chlorine source at room temperature. The as-obtained ternary Ag-modified raspberry-like AgCl/Ag2WO4 composites can facilitate the contact of dye molecules and photocatalysts, exhibiting superior photocatalytic property and good recycling ability towards the decomposition of organic dye under the visible-light irradiation. The reductant addition amounts greatly affect the performance of Ag2WO4 photocatalyst. The optimum composite ratio of Ag-modified AgCl/Ag2WO4 samples show significant enhancement of visible-light photocatalytic activities and the degradation rate constant is about 16 times greater than that of pure Ag2WO4. The highly improved performance of Ag-modified raspberry-like AgCl/Ag2WO4 structure can be ascribed to the surface plasma resonance (SPR) effects of metal Ag and the synergistic effect among composites, accordingly effectively promote the separation of photoinduced electron-hole pairs, widen the absorbance range in the visible light and increase surface area. The h+ and ·OH degraded mechanism for the improved photocatalytic activity of Ag-modified AgCl/Ag2WO4 is proposed based on radical-trapping experiments and ESR spectra records.

Facile preparation of Sn/BiOCl composite oxides and their photocatalytic performance

ABSTRACTSn-doped BiOCl (Sn/BiOCl) photocatalysts were synthesized by a precipitation method using Bi(NO3)3 · 5H2O as a bismuth source, SnCl2 as an Sn source, imidazole hydrochloride as a chlorine source, a solvent, and a template agent. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, surface area analysis (Brunauer, Emmett and Teller [BET]), and diffuse reflectance spectroscopy. The XRD results showed a greater increase in the peak intensity of Sn/BiOCl because of its high degree of crystallinity. The UV–Vis results indicated a redshift from 368 nm (BiOCl) to 418 nm (Sn/BiOCl), leading to the reduced band gap of BiOCl because of Sn doping in BiOCl. The Sn/BiOCl not only retained ultraviolet photocatalytic activity of BiOCl but also showed visible photocatalytic activity. The BET results showed that the surface area of Sn/BiOCl (23.35 m2 ) was bigger than that of BiOCl (13.54 m2 g). The bigger surface show higher photocatalytic activity due to more contact opportunity between reactants. Hence, the increased photocatalytic activity of Sn/BiOCl in the degradation of rhodamine B can be attributed to a higher degree of crystallinity, larger surface area, and broader range of optical absorption. The Sn/BiOCl needed only 20 min under visible light and 40 min under ultraviolet light to completely degrade rhodamine B. Moreover, the photocatalytic experiment did not require any other chemical reagent such as H2O2. The microstructures of BiOCl and Sn/BiOCl ensured that the catalyst still has high recovery rate when it is reused. The microstructures of catalyst have a little of loss.

Efficient α-chlorination of carbonyl containing compounds under basic conditions using methyl chlorosulfate

An efficient method for the α-chlorination of ketones under basic conditions is described using methyl chlorosulfate. Its applicability for the chlorination of other functional groups has also been studied and it is equally useful for the synthesis of α-chloroesters and amides. Methyl chlorosulfate is described for the first time as a positive chlorine source. Some aldol reactions which occur during the chlorination of some substrates are also reported.

Development of a Sustainable Perchlorate-Free Yellow Pyrotechnical Strobe Formulation

Novel yellow-light-emitting pyrotechnical strobe formulations absent of any chlorine sources were developed. The five yellow strobe formulations cover a frequency range of 7 Hz < x < 20 Hz and do not use potassium dichromate, which is frequently applied as a stabilizer. Frequency measurements and a comparison to a literature-known state-of-the-art red reference strobe formulation revealed a comparable flash separation. In addition, the newly developed formulations meet the requirements of the U.S. Environmental Protection Agency and European regulation law REACH (Registration, Evaluation, Authorization and Restriction of Chemicals), as they do not contain any substances of very high concern, heavy metals, or chlorine atoms (Interim Drinking Water Health Advisory for Perchlorate; Office of Science and Technology, Office of Water, Health and Ecological Criteria Division, U.S. Environmental Protection Agency: Washington, DC, 2008). Potential resulting synergies with a proposed replacement candidate for the M...

Copper-catalyzed intermolecular aminochlorination of alkenes

A copper-catalyzed radical and regioselective aminochlorination of alkenes using N-fluoro-benzenesulfonimide (NFSI) and TMSCl as nitrogen and chlorine sources respectively is reported.

Natural Organochlorines as Precursors of 3-Monochloropropanediol Esters in Vegetable Oils.

During high-temperature refining of vegetable oils, 3-monochloropropanediol (3-MCPD) esters, possible carcinogens, are formed from acylglycerol in the presence of a chlorine source. To investigate organochlorine compounds in vegetable oils as possible precursors for 3-MCPD esters, we tested crude palm, soybean, rapeseed, sunflower, corn, coconut, and olive oils for the presence of organochlorine compounds. Having found them in all vegetable oils tested, we focused subsequent study on oil palm products. Analysis of the chlorine isotope mass pattern exhibited in high-resolution mass spectrometry enabled organochlorine compound identification in crude palm oils as constituents of wax esters, fatty acid, diacylglycerols, and sphingolipids, which are produced endogenously in oil palm mesocarp throughout ripening. Analysis of thermal decomposition and changes during refining suggested that these naturally present organochlorine compounds in palm oils and perhaps in other vegetable oils are precursors of 3-MCPD esters. Enrichment and dose-response showed a linear relationship to 3-MCPD ester formation and indicated that the sphingolipid-based organochlorine compounds are the most active precursors of 3-MCPD esters.

Chlorination of α-Cyanoketones and 1, 3-Dicarbonyl Compounds by Using Trichloroisocyanuric Acid as Chlorine Source

Chlorination of <i>α</i>-Cyanoketones and 1, 3-Dicarbonyl Compounds by Using Trichloroisocyanuric Acid as Chlorine Source

First Acid Ionization Constant of the Drinking Water Relevant Chemical Cyanuric Acid from 5 to 35 °C.

Cyanuric acid is present in drinking water when chemicals commonly referred to as dichlor (anhydrous sodium dichloroisocyanurate or sodium dichloroisocyanurate dihydrate) or trichlor (trichloroisocyanuric acid) are used as alternative free chlorine sources. Cyanuric acid and its ionization products combine with hypochlorous acid, forming various chlorinated cyanurates through a series of equilibrium reactions. Methods to measure the free chlorine (hypochlorous acid plus hypochlorite ion) concentration in systems adding cyanuric acid exhibit measurement bias. To overcome this limitation, one option is use of the established water chemistry of the free chlorine and cyanuric acid system to estimate free chlorine concentrations. Unfortunately, the equilibrium water chemistry has only been determined for 25 °C, limiting the usefulness of the water chemistry estimate in actual drinking water systems where temperatures may vary over a wide range (e.g., 5 to 35 °C). As a first step in extending the water chemistry model to relevant drinking water temperatures, the first acid ionization constant (K6) for cyanuric acid (H3Cy) and its first ionization product (H2Cy-) was determined using spectrophotometric techniques from 5 to 35 °C where or and ΔH° = 33.4 ± 1.7 kJ mol-1. As an example of temperature's impact (pH 7), the H2Cy- fraction of total cyanurate (sum of H3Cy and H2Cy-) effectively doubles from 5 to 35 °C. With K6's temperature dependence established, studies can be conducted to update the existing water chemistry model with temperature dependence, allowing free chlorine concentration simulation in drinking water systems with cyanuric acid present.