Chlorine Utilization Research Articles

Novel pathway of stabilized Cu2S volatilization by derivated CH3Cl

Stabilized heavy metals-containing phases and low chlorine utilization limit heavy metals chlorination reactions. The traditional method of adding chlorinating agents can promote heavy metals chlorination volatilization, but the limiting factor has not been resolved and more chlorides are emitted. Herein, a new reaction pathway to promote heavy metals chlorination volatilization through the transformation of stabilized heavy metals-containing phases and chlorine species by the addition of biomass at the sintering is first reported. The Cu volatilization efficiency increased sharply from 50.50% to 93.21% compared with the control, Zn, Pb, and Cd were nearly completely volatilized. Results show that the biomass carbonization process was more important for Cu chlorination volatilization. Stabilized heavy metals-containing phases were converted from Cu2S to CuO and Cu2O with the biochar and oxygen, increasing the activity of Cu. The chlorine species KCl reacted with CH3-containing groups to form CH3Cl, which reacted with CuO with a lower Delta G than HCl and Cl2, increasing the tendency for the conversion of CuO to CuCl. Cu chlorination volatilization process, following shrinking core kinetic model and controlled by chemical reactions. The outcomes fundamentally addresses the limiting step for heavy metals chlorination volatilization, supporting the incineration fly ash harmless treatment.

Utilization of Ozone and Kefir Whey Probiotics as a Green Technology in Coliform Removal in Health Care Facilities Wastewater

Health care facilities wastewater (HWW), such as hospital, is classified as domestic wastewater according to Minister of Environment and Forestry Regulation No.P68/2016. One of the important parameters is total coliform. The disinfection process using chlorine is effective in reducing the number of coliforms, but it is indicated to cause residues and side effects for other microorganisms in the receiving water bodies. This research is an experimental study by utilizing ozone and probiotics from whey kefir to eliminate coliform bacteria, aiming to determine the strategy for choosing a method for removing total coliform bacteria in HWW using the Analytic Hierarchy Process (AHP) approach. Data processing used Expert Choice 2011 software and it was found that the criteria with the highest score were environmental aspects, namely 0.302 and the priority indicator being minimizing the risk of pollution with the highest score, 0.366. Determination of strategies in the process of eliminating coliform bacteria in HWW by making choices, between the use of chlorine, ozone and a combination of ozone and whey kefir probiotics with five criterias approach (environmental, technological, social, economic, and institutional). Ultimate priority by using ozon was chosen with a score of 0.449; use of ozone and probiotics is the second priority with a score of 0.316; and utilization of chlorine with a score of 0.235.

Advantages of ozone disinfection method for water purification over chlorine disinfection

The improvement of various advancements for water sanitization is a significant issue. Among numerous elective drinking water treatment advances, the well-known disinfectant techniques are ozonation and chlorination to treat drinking water. All through the ozonation procedure, it produces biodegradable organic by-products while in the chlorination process, some risky by-products (trihalomethanes and haloacetic acids) are generated. Because of the possible danger of these results, several water purification methods have been reported, such as ozonation, chlorination, UV, etc. During ozonation, exceptionally reactive hydroxyl radicals are produced, which has a crucial effect on purifying water. In this paper, we have discussed the wide use of ozone disinfectants for water treatment with an emphasis on radical chemistry of ozonization as well as advanced oxidation processes instead of the chlorination process, low-cost ozone generation processes, the impact of ozone and chlorine disinfectants on cryptosporidium oocysts, and the removal of seven strains microbes from drinking water. The favorable circumstances, hindrances of the utilization of ozone and chlorine in wastewater treatment, and their confinements in water treatment innovation just as the elective advances, for example, ozone-based oxidation process, catalytic ozonation, photocatalytic oxidation, and so on are additionally clarified in this paper.

Elevated risk of haloacetonitrile formation during post-chlorination when applying sulfite/UV advanced reduction technology to eliminate bromate

The formation of haloacetonitriles (HANs) during chlorination after sulfite/ultraviolet (UV) treatment of bromate (BrO3−) in the presence of amino acids (AAs) was investigated. During sulfite/UV treatment, the primary species hydrated electrons (eaq−) and hydrogen atom radicals (H) dominated the reduction of BrO3− to bromide (Br−), whereas the sulfite anion radicals (SO3−) and H degraded AAs to produce the intermediates HN=C(CH3)–COOH, CH3–CH=NH, and CH3–C≡N via α‑hydrogen abstraction and NH2–hydrogen abstraction mechanisms. During post-chlorination, Br− was converted to HBrO/BrO-, and the HN=C(CH3)–COOH, CH3–CH=NH, and CH3–C≡N groups featured higher bromine utilization factor (BUF) and chlorine utilization factor (CUF) values than AAs, enhancing the formation of dibromoacetonitrile (DBAN) and dichloroacetonitrile (DCAN). The energetic feasibility of the transformation pathway, that is, HN=C(CH3)–COOH, CH3–CH=NH, and CH3–C ≡ N formation via hydrogen abstraction by SO3− and H and their further conversion to HANs, was proved by density functional theory calculations, which showed stepwise negative Gibbs free energy changes (ΔG < 0). The effects of pH and water matrices (e.g., HCO3−, Cl−, Fe3+, and natural organic matter) were comprehensively evaluated. Although 72% of BrO3− was removed by sulfite/UV treatment in the presence of AAs, the cytotoxicity index (CTI) and genotoxicity index (GTI) during post-chlorination increased by 213% and 125%, respectively, due to the formation of 24 CX3R-type disinfection by-products (DBPs), especially brominated DBPs. Accordingly, more attention should be given to the formation of brominated DBPs during post-chlorination when using sulfite/UV processes to remove BrO3− in the presence of AAs. As a solution, using monochloramine instead of chlorine as a disinfectant after the sulfite/UV process could significantly lower the CTI and GTI values by alleviating the formation of brominated DBPs.

Raw Milk Microbiota Modifications as Affected by Chlorine Usage for Cleaning Procedures: The Trentingrana PDO Case.

Milk microbiota represents a key point in raw milk cheese production and contributes to the development of typical flavor and texture for each type of cheese. The aim of the present study was to evaluate the influence of chlorine products usage for cleaning and sanitizing the milking equipment on (i) raw milk microbiota; (ii) the deriving whey-starter microbiota; and (iii) Trentingrana Protected Designation of Origin (PDO) cheese microbiota and volatilome. Milk samples from three farms affiliated to a Trentingrana PDO cheese factory were collected three times per week during a 6-weeks period in which a sodium hypochlorite detergent (period C) was used and during a subsequent 6-weeks period of non-chlorine detergent usage (period NC). Samples were subjected to microbiological [Standard Plate Count; coliforms; coagulase-positive staphylococci; and lactic acid bacteria (LAB)] and metagenomic analysis (amplification of V3-V4 regions of 16S rRNA gene performed on Illumina MiSeq platform). In addition, cheese volatilome was determined by SPME-GC-MS. In the transition from period C to period NC, higher SPC and LAB counts in milk were recorded. Milk metagenomic analysis showed a peculiar distinctive microbiota composition for the three farms during the whole experimental period. Moreover, differences were highlighted comparing C and NC periods in each farm. A difference in microbial population related to chlorine usage in bulk milk and vat samples was evidenced. Moreover, chlorine utilization at farm level was found to affect the whey-starter population: the usually predominant Lactobacillus helveticus was significantly reduced during NC period, whereas Lactobacillus delbrueckii had the exact opposite trend. Alpha- and beta-diversity revealed a separation between the two treatment periods with a higher presence of L. helveticus, L. delbrueckii, and Streptococcus thermophilus in cheese samples after NC detergent period. Cheese volatilome analysis showed a slight decrease in lipolysis during C period in the inner part of the cheese wheel. Although preliminary, these results suggest a profound influence on milk and cheese microbiota, as well as on raw milk cheese production and quality, due to the use of chlorine. However, further studies will be needed to better understand the complex relationship between chlorine and microbiota along all the cheese production steps.

Sustainable utilization of chlorine via converting HCl to Cl2 over a robust copper catalyst

Offering a substantial method to convert HCl to Cl2 over CuCl2/pumice, Deacon process is of great importance in chemical industry. In the process, the difficulty of Cl2 formation/desorption and catalyst re-oxidation have been unanimously recognized as the origin of the instability of CuO-based catalysts. In this work, the stability of the CuO/Al2O3 catalyst was significantly improved by adding Co. The fabricated CuO(12)–CoOx(13)/Al2O3 catalyst showed unprecedented stability with HCl conversion (xHCl) above 80%, lasting for at least 1000 h. The X-ray diffraction (XRD), Raman spectra, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and H2-temperature programmed reduction (H2-TPR) characterizations suggested that the addition of Co greatly enhanced the dispersion of CuO on Al2O3 and hindered the reduction of CuO due to their strong interaction. The results of reaction kinetics suggested that the lattice oxygen participated in the reaction and the reaction order on oxygen was estimated to be 0.15, suggesting that the catalyst obeyed the Mars-van Krevelen (M-K) mechanism, while only small amount of oxygen was required to maintain the activity of catalysts compared to CuO/Al2O3. Density functional theory (DFT) calculations proved that the CuO–CoOx/Al2O3 ternary system was more stable than CuO/Al2O3 binary system and easier to be oxidized by O2, which greatly reduced the difficulty of Cl2 associative desorption.

喷射型单重态氧发生器性能研究

As the heart of chemical oxygen iodine laser (COIL), the singlet oxygen generator (SOG) has been focus of research for many years. A novel eject singlet oxygen generator was designed based on research of industrial ejectors and cyclone separators. Simulations and experiments were performed on the chemical reaction of O2(1). This eject SOG can make larger gas-liquid surface area through nozzle compared with traditional SOGs, and therefore it has a high chemical efficiency. Gas and liquid were separated by a cyclone separator which was designed to fit for the high separation efficiency and low residence time. This SOG has a chlorine utilization of 97%-99% and O2(1) yield of 40%-50%.

Diagnostics and Data Acquisition for Chemical Oxygen Iodine Laser

This paper focuses on the implementation of various diagnostics for optimizing chemical oxygen iodine laser. This paper also dwells on the measurement methodologies and instrumentation employed in these diagnostic systems. The prime diagnostics are for the measurement of vital species in form of iodine, singlet oxygen, and chlorine. Iodine concentration measurement (absorption at λ = 499 nm ), chlorine utilization (absorption at λ = 330 nm), and singlet oxygen yield (emission at λ = 1.27 μm) have been implemented based on optical absorption/emission principle. Furthermore, online Mach number determination, which is critical for supersonic gas flows, laser pulse detection (at λ = 1315 nm ), and flow rate measurement and control over wide range, have been carried out. A dedicated diagnostics and data acquisition system (DDAS) customized for parameter monitoring have been developed. The developed DDAS also serves the purpose of precise operation sequencing and parameter control. It is a 168-channel personal-computer-based system with customized interface electronics employing Visual C++ programming language with user-friendly graphical user interfaces. A detailed uncertainty analysis of various critical parameters has been also presented.

O2(1Δ) Yield Measurement by Raman Spectroscopy With Elimination of Chlorine Fluorescence Interference

Deleterious chlorine fluorescence was found to occur at the same frequency as the Raman scattering of O2(1Δ) and O2(3Σ), seriously affecting the O2(1Δ) yield measurement in the reaction of chlorine with basic hydrogen peroxide by use of the Raman spectroscopy technique. To solve this problem we have taken advantage of the fact that Raman radiation is always strongly polarized while fluorescence is essentially non-polarized in a gaseous medium. When chlorine utilization of a singlet oxygen generator is 88%, O2(1Δ) yield reaches (42.4±7.4)% with the effect of chlorine fluorescence completely eliminated.

Closed loop recycling of chlorine for sustainable development of polyurethane industry

Increasing demand is fueling the booming polyurethane industry worldwide. An impeding issue for polyurethane industry is how to handle the large quantity of hydrogen chloride byproduct generated from the synthesis of intermediates, i.e., isocyanates. In the meantime, the traditional chloro-alkaline process suffers both from the high energy intensity of electrolysis method and the disparity in the chlorine and caustic soda market. To solve these problems, the state-of-the-art chlorine recycling technologies are reviewed and compared. Approaches for cost-effective utilization of chlorine in polyurethane industry are investigated. Chinese academies and enterprises’ on-going effort on the development of a novel hydrogen chloride oxidation process for the synthesis of chlorine is presented. With this process, the closed loop recycling of chlorine can be realized. Tremendous economic, environmental and social benefits can be expected. A wide adoption of this technology will significantly advance the sustainable development of polyurethane industry.

Spray generator of singlet oxygen for a chemical oxygen-iodine laser

A spray type of singlet oxygen generator for driving the Chemical Oxygen-Iodine Laser was developed. Singlet oxygen, O2(1Δg), is generated by a fast reaction of chlorine with basic hydrogen peroxide solution in the form of a dense spray. A mathematical model of this reaction system showed that O2(1Δg) can be generated in this system with a high yield (0.70–0.80), high utilization of chlorine (0.75–0.95), and effective utilization of liquid (0.36–0.54) at very high generator pressures (35–75 kPa). Experimental studies of this reaction system without an efficient separation of liquid proved an efficient O2(1Δg) production characterized by a rather high product of chlorine utilization and O2(1Δg) yield (0.4–0.9) at very high generator pressures (30–80 kPa). This pressure is much higher than the operation pressure used in other generators, which should be beneficial for a pressure recovery system of the COIL. These results provided the basis for designing a centrifugal spray generator with an efficient separation of liquid from the gas flow, which is the subject of the following paper.

Centrifugal spray generator of singlet oxygen for a chemical oxygen-iodine laser

A centrifugal spray generator of singlet oxygen, O2(1Δg), for driving a chemical oxygen-iodine laser was developed and its operation was experimentally studied. Modeling of the liquid separation from the gas flow showed that the separator designed could remove droplets larger than 0.5 μm from gas, which is very important for the laser operation. This result was confirmed by experiments. Experimental studies proved that O2(1Δg) could be produced with a high efficiency (chlorine utilization 0.68–0.87 and O2(1Δg) yield 0.35–0.7) even at very high generator pressures (25–70 kPa), which cannot be attained by other O2(1Δg) generators.

High throughput jet singlet oxygen generator for multi kilowatt SCOIL

A jet flow singlet oxygen generator (JSOG) capable of handling chlorine flows of nearly 1.5 mol s −1 has been designed, developed, and tested. The generator is designed in a modular configuration taking into consideration the practical aspects of handling high throughput flows without catastrophic BHP carry over. While for such high flow rates a cross-flow configuration has been reported, the generator utilized in the present study is a counter flow configuration. A near vertical extraction of singlet oxygen is effected at the generator exit, followed by a 90° rotation of the flow forming a novel verti-horizontal COIL scheme. This allows the COIL to be operated with a vertical extraction SOG followed by the horizontal arrangement of subsequent COIL systems such as supersonic nozzle, cavity, supersonic diffuser, etc. This enables a more uniform weight distribution from point of view of mobile and other platform mounted systems, which is highly relevant for large scale systems. The present study discusses the design aspects of the jet singlet oxygen generator along with its test results for various operating ranges. Typically, for the intended design flow rates, the chlorine utilization and singlet oxygen yield have been observed to be ∼94% and ∼64%, respectively.

Research on Uniform-Droplet Singlet-Oxygen Generator

The formation of a uniform droplet is the key in a uniform-droplet singlet-oxygen generator (SOG). This paper is mainly on the condition of uniform droplet formation. Factors in uniform-droplet formation, such as basic hydrogen peroxide (BHP) liquid velocity, disturbance frequency, and the pressure distribution in the fluid infusion cavity, were analyzed and optimized in order to improve the performance of the uniform-droplet singlet-oxygen generator. The chlorine utilization, O2(1Δ) yield, H2O concentration, and laser power were measured. The output concentration of O2(1Δ) was as high as 2.94 ×1017/cm3. The maximum power density through the nozzle was 121.3 W/cm2.

Experimental and Theoretical Study of Centrifugal Flow Singlet Oxygen Generator

We designed and realized a novel centrifugal flow singlet oxygen generator (CFSOG) that was originally proposed by Emanuel [Proc. SPIE 5448 (2004) 233]. In this device, singlet oxygen O2(1Δ) is generated by the reaction of gaseous Cl2 with aqueous basic hydrogen peroxide (BHP) that flows rapidly along an arc-shaped concave to form a rotating liquid layer, so that the nascent O2(1Δ) generated in the liquid phase will be separated from it quickly to suppress the collision quenching loss of O2(1Δ) with the help of the enormous centrifugal force produced by the rotating fluid. Our preliminary experiment shows that, because the specific reactive surface area of this novel singlet oxygen generator (SOG) is much larger than that of the jet-type SOG normally used in current chemical oxygen–iodine laser (COIL), enhanced performance of O2(1Δ) yield ∼60%, O2(1Δ) partial pressure ∼31 Torr, and an extremely high chlorine utilization within 96–98% have been realized.

A MEMS Singlet Oxygen Generator—Part II: Experimental Exploration of the Performance Space

This paper reports the quantitative experimental exploration of the performance space of a microfabricated singlet oxygen generator (muSOG). SOGs are multiphase reactors that mix H2O2, KOH, and Cl2 to produce singlet delta oxygen, or O2 (a). A scaled-down SOG is being developed as the pump source for a microfabricated chemical oxygen-iodine laser system because scaling down a SOG yields improved performance compared to the macroscaled versions. The performance of the muSOG was characterized using O2 (a) yield, chlorine utilization, power in the flow, molar flow rate per unit of reactor volume, and steady-state operation as metrics. The performance of the muSOG is measured through a series of optical diagnostics and mass spectrometry. The test rig, which enables the monitoring of temperatures, pressures, and the molar flow rate of O2 (a), is described in detail. Infrared spectra and mass spectrometry confirm the steady-state operation of the device. Experimental results reveal O2 (a) concentrations in excess of 1017 cm-3, O2 (a) yield at the chip outlet approaching 80%, and molar flow rates of 02(a) per unit of reactor volume exceeding 600 times 10-4 mol/L/s.

Results of testing a centrifugal bubble singlet-oxygen generator

The results of parametric tests of a centrifugal bubble singlet-oxygen generator based on the reaction of chlorine with an alkaline hydrogen peroxide solution have been given. The utilization of chlorine grows with bubble-layer height, whereas the relative content of O2(1Δ) remains constant. Growth in centrifugal acceleration leads to a more efficient utilization of chlorine. A specific oxygen output of more than 1 mmole·cm−2·sec−1 from the bubble layer for a degree of chlorine utilization of ∼95% and a singlet-oxygen yield of more than 50% has been attained. It has been shown that a centrifugal bubble singlet-oxygen generator is an efficient energy source for an oxygen-iodine laser.

Singlet oxygen generator based on the reaction of chlorine with filament-guided jets of basic hydrogen peroxide

The chlorine utilization efficiency and singlet oxygen concentration are determined as functions of the chlorine flow rate, the base concentration, and the flow rate and temperature of basic hydrogen peroxide in a singlet oxygen generator based on the reaction of chlorine with filament-guided descending basic hydrogen peroxide jets. The effluent gas, without aerosol entrainment, contains about 10% residual chlorine and more than 60% singlet oxygen.

A 2-kW COIL with a square pipe-array JSOG and nitrogen buffer gas

A 2-kW-class chemical oxygen-iodine laser (COIL) using nitrogen buffer gas has been developed and tested since industrial applications of COIL devices will require the use of nitrogen as the buffer gas. The laser, with a gain length of 11.7 cm, is energized by a square pipe-array jet-type singlet oxygen generator (SPJSOG) and employs a nozzle bank with a designed Mach number of 2.5. The SPJSOG has advantages over the traditional plate-type JSOG in that it has less requirements on basic hydrogen peroxide (BHP) pump, and more important, it has much better operational stability. The SPJSOG without a cold trap and a gas-liquid separator could provide reliable operations for a total gas flow rate up to 450 mmol/s and with a low liquid driving pressure of around 0.7 atm or even lower. The nozzle bank was specially designed for a COIL using nitrogen as the buffer gas. The cavity was designed for a Mach number of 2.5, in order to provide a gas speed and static temperature in the cavity similar to that for a traditional COIL with helium buffer gas and a Mach 2 nozzle. An output power of 2.6 kW was obtained for a chlorine flow rate of 140 mmol/s, corresponding to a chemical efficiency of 20.4%. When the chlorine flow rate was reduced to 115 mmol/s, a higher chemical efficiency of 22.7% was attained. Measurements showed that the SPJSOG during normal operation could provide a singlet oxygen yield Y/spl ges/55%, a chlorine utilization U/spl ges/85%, and a relative water vapor concentration w=[H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O]/([O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ]+[Cl <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ])/spl les/0.1.

Measurements of the yield and chlorine utilization of singlet oxygen generator by use of Raman spectroscopy.

A Raman scattering system was used to measure the O2 (a1delta) yield end the chlorine utilization in a singlet oxygen generator of chemical oxygen iodine laser with nitrogen diluent. We present the results from the tests that conducted on a 0.1-mol/s jet-type singlet oxygen-iodine generator. On the basis of the current reported uncertainty of the Raman cross section, the error in the yield measurement is calculated to be less than 8%, and the error of the chlorine utilization is 12%.