Unveiling the geometric site dependent activity of spinel Co_(3)O_(4)for electrocatalytic chlorine evolution reaction

Spinel cobalt oxide(Co_(3)O_(4)),consisting of tetrahedral Co^(2+)(CoTd)and octahedral Co^(3+)(CoOh),is considered as promising earth-abundant electrocatalyst for chlorine evolution reaction(CER).Identifying the catalytic contribution of geometric Co site in the electrocatalytic CER plays a pivotal role to precisely modulate electronic configuration of active Co sites to boost CER.Herein,combining density functional theory calculations and experiment results assisted with operando analysis,we found that the Co_(Oh) site acts as the main active site for CER in spinel Co_(3)O_(4),which shows better Cl^(-)adsorption and more moderate intermediate adsorption toward CER than CoTd site,and does not undergo redox transition under CER condition at applied potentials.Guided by above findings,the oxygen vacancies were further introduced into the Co_(3)O_(4) to precisely manipulate the electronic configuration of Co_(Oh) to boost Cl^(-)adsorption and optimize the reaction path of CER and thus to enhance the intrinsic CER activity significantly.Our work figures out the importance of geometric configuration dependent CER activity,shedding light on the rational design of advanced electrocatalysts from geometric configuration optimization at the atomic level.

Effects of Chlorine and Chlorine Monoxide on Stratospheric Ozone Depletion

This paper presents a system approach of mass balance calculations of ozone and other species under diffusion-convection-reaction processes to study the impacts of major ozone-depleting chemicals, chlorine (Cl) and chlorine monoxide (ClO), and the effect of photolysis on ozone concentrations, ozone depletion, total ozone abundance, and ozone layer along the altitude in the stratosphere. The calculated ozone concentrations and profile of the layer followed a similar trend and were generally in good agreement with the measurements above the tropical area. The calculated peak of the layer was at the same mid-stratosphere at Z = 30 km with a peak concentration and total ozone abundance about 20% higher than the measured peak concentration of 8.0 ppm and total abundance of 399 DU. In the presence of Cl and ClO, the calculated ozone concentrations and total abundance were substantially reduced. Cl generally depleted more uniformly of ozone across the altitude, while ClO reduced substantially the ozone in the upper stratosphere and thus shifted the peak of the layer to a much lower elevation at Z = 14 km. Although both ClO and Cl are active ozone-depleting chemicals, ClO was found to have a more pronounced impact on ozone depletion and distribution than Cl. The possible explanations of these interesting phenomena were discussed and elaborated. The approach and calculations in this paper were shown to be useful in providing an initial insight into the structure and behavior of the complex ozone layer.

Effects of surface chlorine atoms on charge distribution and reaction barriers for photocatalytic CO_(2)reduction

Photocatalytic CO_(2)reduction to produce high value-added carbon-based fuel has been proposed as a promising approach to mitigate global warming issues.However,the conversion efficiency and product selectivity are still low due to the sluggish dynamics of transfer processes involved in proton-assisted multi-electron reactions.Lowering the formation energy barriers of intermediate products is an effective method to enhance the selectivity and productivity of final products.In this study,we aim to regulate the surface electronic structure of Bi_(2)WO_(6)by doping surface chlorine atoms to achieve effective photocatalytic CO_(2)reduction.Surface Cl atoms can enhance the absorption ability of light,affect its energy band structure and promote charge separation.Combined with DFT calculations,it is revealed that surface Cl atoms can not only change the surface charge distribution which affects the competitive adsorption of H_(2)O and CO_(2),but also lower the formation energy barrier of intermediate products to generate more intermediate*COOH,thus facilitating CO production.Overall,this study demonstrates a promising surface halogenation strategy to enhance the photocatalytic CO_(2)reduction activity of a layered structure Bi-based catalyst.

Full-scale study of removal effect on Cyclops of zooplankton with chlorine dioxide

Cyclops of zooplankton propagated excessively in eutrophic water body and could not be effectively inactivated by the conventional disinfections process like chlorination due to its stronger resistance to oxidation. In this paper, a full-scale study of chlorine dioxide preoxidation cooperating with routine clarification process for Cyclops removal was conducted in a waterworks. The experimental results were compared with that of the existing prechlorination process in several aspects: including the Cyclops removal efficiencies of water samples taken from the outlets of sedimentation tank and sand filter and the security of drinking water and so on. The results showed that chlorine dioxide might be more effective to inactivate Cyclops than chlorine and Cyclops could be thoroughly removed from water by pre-dosing chlorine dioxide process. The GC-MS examination and Ames test further showed that the sort and amount of organic substance in the treated water by chlorine dioxide preoxidation were evidently less than that of prechlorination and the mutagenicity of drinking water treated by pre-dosing chlorine dioxide was substantially reduced compared with prechlorination.

Pilot-scale study of removal effect on Chironomid larvae with chlorine dioxide

Chironomid larvae propagated excessively in eutrophic water body and could not be effectively inactivated by the conventional disinfection process like chlorination due to its stronger resistance to oxidation. In this paper, a pilot-scale study of chlorine dioxide preoxidation cooperating with routine clarification process for Chironomid larvae removal was conducted in Shenzhen Waterworks in Guangdong Province, China. The experimental results were compared with that of the existing prechlorination process in several aspects, including the Chironomid larvae removal efficiencies of water samples taken from the outlets of sedimentation tank, sand filter, the security of drinking water and so on. The results showed that chlorine dioxide might be more effective to inactivate Chironomid larvae than chlorine and Chironomid larvae could be thoroughly removed from water by pre-dosing chlorine dioxide process. The GC-MS examination and Ames test further showed that the sort and amount of organic substance in the treated water by chlorine dioxide preoxidation were evidently less than that ofprechlorination and the mutagenicity of drinking water treated by pre-dosing chlorine dioxide was substantially reduced compared with prechlorination.

Inactivation of Resistant Mycobacteria mucogenicum in Water:Chlorine Resistance and Mechanism Analysis

Objective To better understand the mechanism of chlorine resistance of mycobacteria and evaluate the efficiency of various disinfection processes.Methods Inactivation experiments of one strain Mycobacteria mucogenicum,isolated from a drinking water distribution system in South China were conducted with various chlorine disinfectants.Inactivation efficiency and disinfectant residual,as well as the formation of organic chloramines,were measured during the experiments.Results This strain of M.mucogenicum showed high resistance to chlorine.The CT values of 99.9% inactivation by free chlorine,monochloramine and chlorine dioxide were detected as 29.6±1.46,170±6.16,and 10.9±1.55 min（mg/L） respectively,indicating that chlorine dioxide exhibited significantly higher efficiency than free chlorine and monochloramine.It was also found that M.mucogenicum reacted with chlorine disinfectants more slowly than S.aureus,but consumed more chlorine disinfectants during longer time of contact.Lipid analysis of the cell construction revealed that 95.7% of cell membrane lipid of M.mucogenicum was composed of saturated long chain fatty acids.Saturated fatty acids were regarded as more stable and more hydrophilic which enabled the cell membrane to prevent the diffusion of chlorine.Conclusion It was concluded that different compositions of cell membrane might endow M.mucogenicum with a higher chlorine resistance.

Study of Non-Ideal Effects for Extended Gate Field Effect Transistor Chlorine Ion Sensing Device

We use the extended gate field effect transistor (EGFET)as the structure of the chlorine ion sensor,and the chlorine ion ionophores (ETH9033 and TDDMAC1)are incorporated into solvent polymeric membrane (PVC/DOS),then the chlorine ion selective membrane is formed on the sensing window,and the fabrication of the EGFET chlorine ion sensing device is completed.The surface potential on the sensing membrane of the EGFET chlorine ion sensing device will be changed in the different chlorine ion concentration solutions,then changes further gate voltage and drain current to detect chlorine ion concentration.We will study non-ideal effects such as temperature,hysteresis and drift effects for the EGFET chlorine ion sensing device in this paper,these researches will help us to improve the sensing characteristics of the EGFET chlorine ion sensing device.

Investigation of heavy metal partitioning influenced by flue gas moisture and chlorine content during waste incineration

The impact of moisture on the partitioning of the heavy metals including Pb,Zn,Cu and Cd in municipal solid waste （MSW） was studied in a laboratory tubular furnace.A thermodynamic investigation using CHEMKIN software was performed to compare the experimental results.Simulated waste,representative of typical MSW with and without chlorine compounds,was burned at the background temperature of 700 and 950°C,respectively.In the absence of chlorine,the moisture content has no evident effect on the volatility of Pb,Zn and Cu at either 700 or 950°C,however,as flue gas moisture increasing the Cd distribution in the bottom ash increased at 700°C and reduced at 950°C,respectively.In the presence of chlorine,the flue gas moisture reduced the volatility of Pb,Zn and Cu due to the transformation of the more volatile metal chlorides into less volatile metal oxides,and the reduction became significant as chlorine content increase.For Cd,the chlorine promotes its volatility through the formation of more volatile CdCl 2.As a result,the increased moisture content increases the Pb,Zn,Cu and Cd concentrations in the bottom ash,which limits the utilization of the bottom ash as a construction material.Therefore,in order to accumulate heavy metals into the fly ash,MSW should be dried before incineration.

VARIATIONS IN ISOTOPIC COMPOSITIONS OF CHLORINE IN EVAPORATION-CONTROLLED SALT LAKE BRINES OF QAIDAM BASIN,CHINA

The variations in the isotopic compositions of chlorine in evaporation controlled saline lake brines were determined by using an improved procedure for precise measurement of chlorine isotopes based on Cs 2Cl + ion by thermal ionization mass spectrometry. The results showed that variation in δ 37 Cl values in these evaporation controlled brines are attributable to evaporation of brine accompanied by the deposition of saline minerals. The isotopic fractionation of chlorine between the deposited saline mineral and the co existing brine caused the variation of δ 37 Cl values in the brine. In general the isotopic fractionation of chlorine in nature indicates enrichment of 3 7Cl in the solid phase relative to 3 5Cl. The reverse isotopic fractionation of chlorine in which 3 5Cl is enriched in the solid phase, was observed to some extent during quick deposition under laboratory conditions as well as in nature. The mechanism of isotopic fractionation of chlorine during evaporation deposition was studied.

Effects of Chlorine Dioxide Gas on Postharvest Physiology and Storage Quality of Green Bell Pepper (Capsicum frutescens L.var.Longrum)

The effects of treatment of chlorine dioxide （C1Oz） gas on postharvest physiology and preservation quality of green bell peppers were studied. Green bell peppers were collected in bags and treated with 0, 5, 10, 20, and 50 mg L^-1 ClO2 gas at 10±0.5℃ for over 40 d, and the changes in postharvest physiology and preservation quality of the peppers were evaluated during the storage. The inhibition of rot of the peppers was observed for all the tested ClO2 gas treatments. The rot rates of the treated samples were 50% lesser than those of the control after day 40 of storage. The highest inhibitory effect was obtained after 50 mg L^-1 ClO2 gas treatment, where the peppers did not decay until day 30 and showed only one-fourth of the rot rate of the control at day 40 of storage. The respiratory activity of the peppers was significantly （P〈0.05） inhibited by 20 and 50 mg L^-1 ClO2 treatments, whereas no significant effects on respiratory activity were observed with 5 and 10 mg L^-1 ClO2 treatments （P〉0.05）. Except for 50 mg L^-1 ClO2, malondialdenyde （MDA） contents in the peppers treated with 5, 10, or 20 mg L^-1 ClO2 were not significantly （P〉0.05） different from those in the control. Degradation of chlorophyll in the peppers was delayed by 5 mg L-1ClO2, but promoted by 10, 20, or 50 mg L^-1 ClO2. The vitamin C content, titratable acidity, and total soluble solids of the peppers treated by all the tested ClO2 gas did not significantly change during the storage. The results suggested that ClO2 gas treatment effectively delayed the postharvest physiological transformation of green peppers, inhibited decay and respiration, maintained some nutritional and sensory quality, and retarded MDA accumulation.

Roasting and chlorine leaching of gold-bearing refractory concentrate:Experimental and process analysis

This paper deals with gold extraction from a refractory concentrate by chlorine leaching.The process considers a pre-treatment of refractory materials by low temperature oxidation carried out with low oxygen concentration.The oxidized material is treated by leaching with brine.After gold adsorption/reduction onto activated carbon,iron and base metals can be precipitated by NaOH.Roasting tests show the necessity to carry out a thermal pre-treatment at least at 550°C to obtain a reduction of sulfur and mercury in the material(50%and 90%,respectively).Highest gold extraction yield(around 93%)is obtained in the leaching test performed with material sample treated at 650°C.This result confrms the necessity to optimize the thermal pre-treatment to improve Au recovery and to reduce chlorine consumption.A comparison with conventional cyanidation confrms that chlorination could be an useful alternative:in fact,gold extraction yield is quite low:57%in non-pre-treated material and 25%in pre-treatment material.

Effects of inorganic chlorine source on dioxin formation using fly ash from a fluidized bed incinerator

Chlorine source is indispensable for polychlorinated dibenzo-p-dioxin and furan （PCDD/F） formation during municipal solid waste （MSW） incineration. Inorganic chlorine compounds were employed in this study to investigate their effects on PCDD/F formation through heterogeneous synthesis on fly ash surfaces. A fly ash sample obtained from a fluidized bed incinerator was sieved to different size fractions which served as the PCDD/F formation sources. The capability of different metal chlorides which facilitate the formation of PCDDs/Fs was found to follow the trends： Na 〈 Mg 〈 K 〈 AI 〈 Ca, when two particle fractions of 〉177 μm and 104-125 μm were used in the experiments. However, the capability of NaCI, MgCl2 and KCI did not seem much different from each other, whereas CaCl2 and AlCl3 were much more active in PCDD/F formation. NaCl and MgCl2 were relatively effective to produce more PCDDs, while KC1, AICl3 and CaCl2 generated more PCDFs during heterogeneous reactions occurring on fly ash. 2,3,7,8-TCDF was the most significant contributor to the toxicity of the PCDDs/Fs formed from inorganic chlorine sources. Decreasing the sizes of fly ash particles led to more active formation of PCDDs/Fs when NaCl was used as inorganic chlorine in the experiment. The highest PCDDs/Fs produced from particles with size 〈37 μm, while the lowest PCDDs/Fs produced from particles with size 〉177μm. The toxicity generally increased with decreasing size of the fly ash particles. The formation of PCDDs was mainly facilitated by the two size fractions, 104-125 μm and 〈37μm, while the formation of PCDFs was favored by the two other size fractions, 〉177 μm and 53-104 μm.

Modeling of residual chlorine in water distribution system

Water quality within water distribution system may vary with both location and time. Water quality models are used to predict the spatial and temporal variation of water quality throughout water system. A model of residual chlorine decay in water pipe has been developed, given the consumption of chlorine in reactions with chemicals in bulk water, bio films on pipe wall, in corrosion process, and the mass transport of chlorine from bulk water to pipe wall. Analytical methods of the flow path from water sources to the observed point and the water age of every observed node were proposed. Model is used to predict the decay of residual chlorine in an actual distribution system. Good agreement between calculated and measured values was obtained.

Preparation and Evaluation of Novel Solid Chlorine Dioxide-based Disinfectant Powder in Single-pack

Objective To prepare and evaluate novel chlorine dioxide-based disinfectant powder in single-pack that is more convenient for use and transportation. Methods Orthogonal experiment was performed to determine the recipe of the disinfectant powder. Stability test, suspension quantitative bactericidal test, simulation field triM, and animal toxicity test were carded out to observe its bactericidal and toxicological effects. Results The orthogonal experiment showed that the type of water solution had no effect on the disinfectant powder and the best ratio of sodium chlorite to solid acid was 1：3. Ten grams of the disinfectant powder was fully dissolved in 20 mL water for 2 min, and diluted to 500 mL in water. After 5-10 min, the concentration of chlorine dioxide （CIO2） solution was 266 mg/L to 276 mg/L. After stored at 54℃ for 14 d, the average concentration of CIO2 was decreased by 5.03%. Suspension quantitative bactericidal test showed that the average killing logarithm （KL） value for both Staphylococcus aureus and Escherichia coli in 100 mg/L CIO2 solution for 2 min was over 5.00. In simulation field triM, the average descending KL value for Escherichia coli in the solution containing 100 mg/L CIO2 for 5 min was over 3.00. The mouse acute LD50 in the solution 5 times exceeded 5000 mg/kg. The disinfectant powder was not toxic and irritative to rabbit skin and had no mutagenic effect on mouse marrow polychromatic erythrocytes （PCE）. Conclusion The stability and bactericidal efficacy of solid chlorine dioxide-based disinfectant powder in single-pack are good. The solution containing 100 mg/L CIO2 can kill vegetative forms of bacteria. The concentration of CIO2 on the disinfecting surface of objects is 100 mg/L. The disinfectant powder is not toxic and irritative.

Kinetics of aniline oxidation with chlorine dioxide

For the first time, kinetics of aniline oxidation with chlorine dioxide(ClO 2) were investigated systematically by detecting concentration of aniline with HPLC at regular intervals. Results showed that the reaction was first-order both in ClO 2 and in aniline, and the oxidation reaction could be described as second-order reaction. Stoichiometric factor η was experimentally determined to be 2 44. The second-order-reaction rate constant k was 0 11 L/(mol·s) under condition of pH 6 86 and water temperature(T w) 287K. Reaction activation energy was 72 31 kJ/mol, indicating that the reaction could take place under usual water treatment conditions. The reaction rate constants in acidic and alkali media were greater than that in neutral medium. Chlorite ion could slightly increase reaction rate in acidic medium. p-aminophenol and azobenzene were detected by GC-MS as intermediates.

Removal effect on Mesocyclops leukarti and mutagenicity with chlorine dioxide

Mesocyclops leukarti of zooplankton propagates excessively in eutrophic water body and it cannot be effectively inactivated by the conventional drinking water treatment process. In order to tackle this problem, a study of removal effect on Mesocylops leukarti with chlorine dioxide in a waterworks was performed. The results showed that Mesocyclops leukarti could be effectively removed from water by 1.0 mg/L chlorine dioxide prcoxidation combined with the conventional drinking water treatment process. Higher oxidizability and molecular state of chlorine dioxide in water is the key to the inactivation of Mesocyclops leukarti. The chlorite, disinfection by-products （DBPs） of chlorine dioxide, was stable at 0.45 mg/L, which is lower than that critical value of the USEPA. GC-MS examination showed that the quantity of organic substance in the water treated by chlorine dioxide obviously decreased. Ames test further revealed that the mutagenicity was reduced by chlorine dioxide with respect to prechlorine. The propagation ofMesocyclops leukorti can be inactivated effectively and safely by chlorine dioxide pre-oxidation.

Research on the explosion characteristics of chlorine dioxide gas

The explosion characteristics of chlorine dioxide gas have been studied for the first time in a cylindrical exploder with a shell capacity of 201. The experimental results have indicated that the lower concentration limit for the explosive decomposition of chlorine dioxide gas is 9.5% （[ClO2]/[air]）, whereas there is no corresponding upper concentration limit. The maximum pressure of explosion relative to the initial pressure was measured as 0.024 MPa at 10% ClO2 and 0.641 MPa at 90% ClO2. The induction time （the time from the moment of sparking to explosion） at 10% ClO2 was 2195 ms, but at 90% ClO2 the induction time was just 8 ms. The explosion reaction mechanism of ClO2 is of a degenerate chain-branching type involving the formation of a stable intermediate （Cl2O3）, from which the chain branching occurs.

Chlorine-anion doping induced multi-factor optimization in perovskites for boosting intrinsic oxygen evolution

The oxygen evolution reaction(OER) plays a crucial role in many electrochemical energy technologies,and creating multiple beneficial factors for OER catalysis is desirable for achieving high catalytic efficiency.Here,we highlight a new halogen-chlorine(Cl)-anion doping strategy to boost the OER activity of perovskite oxides.As a proof-of-concept,proper Cl doping at the oxygen site of LaFeO3(LFO) perovskite can induce multiple favorable characteristics for catalyzing the OER,including rich oxygen vacancies,increased electrical conductivity and enhanced Fe-O covalency.Benefiting from these factors,the LaFeO2.9-δCl0.1(LFOCl) perovskite displays significant intrinsic activity enhancement by a factor of around three relative to its parent LFO.This work uncovers the effect of Cl-anion doping in perovskites on promoting OER performance and paves a new way to design highly efficient electrocatalysts.

The decay kinetics of residual chlorine in cooling seawater simulation experiments

To find out the decay character of residual chlorine （RC） in the sea water, the concentration of RC was analyzed by N, N-diethyl-p-phenylenediamine （DPD） method under different simulation experimental conditions, in which salinity, temperature, and Chemical Oxygen Demand （COD） were selected. The water used in the experiment was the mixture of aging ocean water, coastal water and extracting solution of coastal sediment at appropriate level. Results are shown as follows： （1） Piecewise function can well reflect the decay dynamics of RC in the cooling seawater. Concretely, the decay dynamics of first 1 min is too rapid to ascertain using a specific kinetic function, and that of the time from 1 to 30 min is fit for the first-order kinetic model. （2） The results could be the foundation of the chemical behavior of RC in seawater, and be used as not only the guidance of the coastal power plants production and sea water desalting companies, but also the establishment of the correlative trade standard.

Improved blue quantum dot light-emitting diodes via chlorine passivated ZnO nanoparticle layer

In blue quantum dot light emitting diodes(QLEDs),electron injection is insufficient,which would degrade device efficiency and stability.Herein,we employ chlorine passivated ZnO nanoparticles as electron transport layer to facilitate electron injection into QDs effectively.Moreover,it suppresses exciton quenching at the QD/ZnO interface by blocking charge transfer channel.As a result,the maximum external quantum efficiency of blue QLED was increased from 2.55%to 4.60%,and the operation lifetime of blue QLED was nearly 4 times longer than that of the control device.Our work indicates that election injection plays an important role in blue QLED efficiency and stability.