Amount Of Residual Chlorine Research Articles

Residual chlorine prevents full densification of flash sintered yttria-stabilized zirconia ceramics

The densification of yttria-stabilized zirconia (YSZ) during flash sintering is strongly dependent on the amount of residual chlorine in the sintered bodies. The residual chlorine, present as a remnant from powder synthesis, hinders densification after it is trapped and vaporized in the rapidly closing pores, limiting the final density at around 87 – 93% of theoretical. We show that this phenomenon is likely to affect all YSZ powders synthesized from chloride precursors unless the residual chlorine is reduced to ≤ 0.03 wt% before the onset of the flash sintering. This can be universally achieved by thermal purification of green bodies at a high temperature or by chemical purification in ammonium hydroxide. Furthermore, added binder in commercially available Tosoh zirconia TZ-powders (TZ-3YB, TZ-3YB-E) helps to significantly reduce chlorine content during binder burnout which in turn allows flash sintering into a high density even without green body purification.

The mixed-order chlorine decay model with an analytical solution and corresponding trihalomethane generation model in drinking water

Ensuring effective drinking water disinfection, remaining a certain amount of residual chlorine, and controlling disinfection by-product formation were very important for guarantying water quality safety and protecting public health; thus, the chlorine decay model and corresponding disinfection by-product formation model were necessary. This paper proposed a mixed-order chlorine bulk decay model (two parameters) based on Taylor's formula and derived its analytical solution. The accuracy of the mixed-order model was evaluated by comparing it with the nth-order model. To optimize the model and reduce the number of parameters required to be calibrated, the relationship of parameters with temperature, initial chlorine concentration, TOC and inorganic substance (ammonia nitrogen and iodide ion) was explored. The result proved that one of the parameters could be regarded as temperature dependent only. Meanwhile, the temperature equation of the model parameters was established by the Arrhenius formula. Subsequently, this paper selected trihalomethane as the target and study the linear relationship between chlorine consumption and trihalomethane formation. The results indicated that the liner slope had little correlation with initial chlorine concentration and temperature. On this basis, the corresponding trihalomethane model was built and its performance was proven to be good. The modeling developed in this work could be applied to drinking water distribution systems for residual chlorine and trihalomethane prediction, and provided a reference for the decision involving water quality.

Monitoring kvaliteta vode nakon poplava

Safe drinking water is one of the most important conditions for a healthy life. However, in case of disasters and emergencies, the water is often contaminated with various impurities of physical, chemical and/or biological origin. These contaminations can lead to a number of health problems, including various infectious diseases. For that reason, it is important to act preventively, and to perform appropriate treatment and water purification in a timely and urgent manner, depending on the type of pollution. In order to determine the type of pollution and perform the appropriate water treatment, the precondition is arranging certain chemical analyzes and monitoring of water quality through quality parameters. Since our time and economic resources are limited in the first moments of the accident, it is not possible to monitor all the parameters, so we monitor the most important: pH value, amount of residual chlorine, color, turbidity and the presence of pathogens. However, even when the type of pollution is determined, it is sometimes not possible to do centralized water purification immediately. Therefore, it is important to know the methods that can independently, and with the help of some handy tools, be applied in our household (eg. disinfection by boiling water or using some of the chemicals for disinfection; sedimentation, etc.). Using these methods, at least a physiological minimum can be provided for family members in the first moments after the accident, until a centralized purification is performed.

Using simulation model to determine the regulation and to optimize the quantity of chlorine injection in water distribution networks

Water can be disinfected by various techniques. Chlorination is the most prevalent and the cheapest method in this regard. One of the most significant factors in chlorination is the location and the amount of chlorine injections, both of which must be chosen in a way that the amount of chlorine remaining in all sections of a city’s water distribution network is within the standard range, and the associated costs are reduced to a considerable extent. Therefore, in this research, we have implemented a technique which takes both of those issues, i.e., the amount of residual chlorine in pipes and the quantity of chlorine consumed in diverse sections of the water distribution network into account leading to a much more cost-effective water disinfection technique. Our technique shows that municipal water distribution network, are effectively in tune with the current highest standards set in the water disinfection procedure for the lowest possible cost. For modeling the water allocation network, the WaterGems software was used. Using this software, the network was modeled into two practical methods, i.e., gravity and direct pumping methods. The productivity of gravity as well as direct pumping methods was shown to control the optimal chlorine injection rate by resolving the two applied models of water distribution networks. The results showed that the residual chlorine content in 70% of the direct pipe network was within the standard range and in 100% of the tubes in the gravity distribution network lower than the standard. Also, the chlorine which was consumed in the direct pumping network was 7% lesser than that in the gravity distribution network. This research showed that the adjusting of chlorine injection into direct-pumped networks compared with gravity distribution networks was more feasible and also required less chlorine consumption.

Wall Decay Coefficient Estimation in a Real-Life Drinking Water Distribution Network

Injection of chlorine as a disinfectant and the correct prediction of the residual amount in water distribution networks are key points and important principles in the quality management of these networks. It is necessary to determine and measure some parameters to develop an effective model in this field. In this study, for the first time, the Simple Hybrid of Genetic Algorithm and Particle Swarm Optimization (SHGAPSO) method along with GA and PSO algorithms are used for qualitative calibration of a real-life water distribution network in Iran to minimize the difference between observed chlorine concentrations at measurement points and the concentrations simulated by the EPANET2.0 hydraulic-qualitative simulation model. The objective functions in this study are Mean Absolute Error (MAE) and Mean Square Error (MSE). The decision variables include bulk (kb) and wall (kw) chlorine decay coefficients are estimated by SHGAPSO, GA, and PSO methods during 4 scenarios. In this study, the amount of residual chlorine in the network was measured by a digital chlorine meter in different days of the year 2018. The results show that SHGAPSO method enhanced the performance of GA and PSO algorithms in the scenarios studied. In scenario 3, this difference was noticeable. Also, scenario 4 with the lowest values of objective functions is selected to estimate the coefficients kw and kb as the best scenario, and finally the qualitative calibration of the network.

Characterization of corrosion scale formed on stainless steel delivery pipe for reclaimed water treatment

To reveal corrosion behavior of stainless steel delivery pipe used in reclaimed water treatment, this research focused on the morphological, mineralogical and chemical characteristics of stainless steel corrosion scale and corroded passive film. Corrosion scale and coupon samples were taken from a type 304 pipe delivering reclaimed water to a clear well in service for more than 12 years. Stainless steel corrosion scales and four representative pipe coupons were investigated using mineralogy and material science research methods. The results showed corrosion scale was predominantly composed of goethite, lepidocrocite, hematite, magnetite, ferrous oxide, siderite, chrome green and chromite, the same as that of corroded pipe coupons. Hence, corrosion scale can be identified as podiform chromite deposit. The loss of chromium in passive film is a critical phenomenon when stainless steel passive film is damaged by localized corrosion. This may provide key insights toward improving a better comprehension of the formation of stainless steel corrosion scale and the process of localized corrosion. The localized corrosion behavior of stainless steel is directly connected with reclaimed water quality parameters such as residual chlorine, DO, Cl− and SO42−. In particular, when a certain amount of residual chlorine in reclaimed water is present as an oxidant, ferric iron is the main chemical state of iron minerals.

保管水の長期水質調査

We examined changes in the quality of drinking water stockpiled under various conditions for emergency use. The results indicated that the change in the quality of the stocked water was influenced mainly by the preservation period and not by the amount of water in the bottle. To maintain water quality, the amount of residual chlorine is less important than using sufficiently sterilized water, bottles and caps in the bottling process. Washing the bottles with a small amount of boiling water was not sufficient to ensure complete inhibition of microbial growth.

Adhesion Characteristics between Chemical Vapor Deposited Cu and TiN Films: Aspects of Process Integration

This paper examines the properties of Cu films deposited on different TiN substrates. The TiN substrates were prepared using TiCl4/NH3 chemistry based chemical vapor deposited (CVD) TiN process by varying the preparation methods and temperatures. Properties examined include morphology and crystallinity as well as adhesion characteristics of the Cu films on the TiN substrates. It was found that the Cu film properties were strongly affected by the overall stress in the multi-layer structure and the amount of residual chlorine (Cl) in the TiN film. When the stress conditions of the Cu and TiN films are the same, good adhesion occurred. Higher Cl concentrations caused adhesion enhancement of the Cu film; however, surface morphology was degraded. Angle resolved X-ray photoelectron spectroscopy (XPS) results and depth analysis implied that fast Cu diffusion occurred in the near-interface region. It is suggested that Cl enhances the diffusion of Cu, resulting in the formation of a diffusion interface that improves adhesion.

Effect of Methanation of Active Carbon Support on the Barium-Promoted Ruthenium Catalyst for Ammonia Synthesis

The effect of the induced methanation of hydrogen-treated active carbon (HTAC) support on the structural change and then catalytic activity over Ba-promoted Ru/HTAC catalysts (Ba(NO3)2 and RuCl3 were precursors) for ammonia synthesis was investigated. It was found that a moderate degree of the methanation of HTAC support increased the catalyst surface area and pore volume significantly rather than destroyed the porous structure. But the methanation of carbon support might accelerate the growth of Ru particles, which finally led to the low activity. We suggested that both the dechlorination temperature (refer to the reductive dechlorination of RuCl3 to form Ru on HTAC) and the hydrogenolysis temperature (refer to the hydrogenolysis of Ba(NO3)2 on Ru/HTAC) have binary effects on the catalytic activity, respectively. On the one hand, the dechlorinating effect and the hydrogenolysis effect increased with the increase of H2 treatment temperature. On the other hand, simultaneously the methanation degree of the support increased too in above both processes. The performance of the catalyst was the combined result of the interaction of the amount of residual chlorine, Ru particle size, and the active promoter component. A respective control of the methanation degree during the catalyst preparation and activation processes was suggested to be necessary for the practical use of the promoted Ru/C catalyst.

Corrosion behaviour of TiN films obtained by plasma-assisted chemical vapour deposition

Titanium nitride (TiN) coatings with a dense structure were prepared on high-speed steel by plasma-assisted chemical vapour deposition (PACVD). The electrochemical polarization measurement of TiN coating was compared with that of the uncoated substrate. It was found that the TiN coating had a higher corrosion potential, and a lower corrosion rate (current density), about three orders of magnitude less than for the steel substrate. The major corrosion mechanism of TiN was pitting corrosion through surface defects and/or open pores. The number and size of pits decreased with the chlorine content of the film. The TiN coating deposited by PACVD, regardless of the amount of residual chlorine, proved to be a good anti-corrosion coating on a steel substrate.

Dependence of Residual Chlorine Amount on Al Grain Size

From the investigation of the thermal desorption spectroscopy (TDS) results, it was found that the amount of residual chlorine on Al films increased with increasing Al grain boundary length after 60°C etching and rinsing. The aluminum surface morphology, which was observed by atomic force microscopy (AFM) after etching, indicated that the Al surface was etched along grain boundaries. Consequently, residual chiorine was trapped at the ditches of grain boundaries which were engraved by etching. In the case of -10°C etching, residual chlorine was hardly trapped at the ditches of grain boundaries because engraving along grain boundaries by etching was suppressed at low temperature.

Papillomas on Fish Exposed to Chlorinated Wastewater Effluent<xref ref-type="fn" rid="FN2">2</xref>

The presence of carcinogenic and mutagenic chemical(s) in the effluent of a wastewater treatment plant was indicated by papillomas developing on caged black bullheads (Ictalurus melas), hepatic enzyme induction in exposed fish, and Ames test mutagenicity of organic extracts of the wastewater. Although virus-like particles have been reported in papillomas of several other fish species, no evidence was obtained for the presence of viruses in the black bullhead papillomas. Mutagenic and carcinogenic chemicals were not identified in the wastewater, but chlorination was implicated as a factor contributing to the induction of the papillomas. The prevalence of papillomas on wild black bullheads exposed to the effluent decreased from 73 to 23% after the amount of residual chlorine (CAS: 7782-50-5) in the effluent leaving the chlorine contact chamber was reduced from 1.3-3.1 mg/liter to 0.25-1.2 mg/liter.

Influence of Heat Treatment on Aluminum Oxide Films on Silicon

Properties of aluminum oxide films deposited on silicon by hydrolysis of AlCl3 depend on the growth temperatures. The influence of subsequent heat treatments on the film properties and structures have been investigated in films grown at 700 and 830°C. Etch rates and electron-diffraction patterns indicated that the properties of the films grown at 700°C were not converted to those of the 830°C-grown films even after the heat treatment at 900°C in argon. The amount of residual chlorine in low-temperature films determined by MeV He+ ion backscattering technique, reduced from 2 to 0.9 at.% after the heat treatment at 900°C but still exceeded that (≲0.02 at.%) for the film deposited at 830°C. A small amount of silicon (5 at.% at the surface) diffused through the films deposited at 700°C after the heat treatment at 900°C. In contrast, the 830°C-deposited film did not change following the heat treatment at 900°C in argon atmosphere. Comparisons between the backscattering data obtained from the films treated under oxidizing conditions and those from reference standards indicated oxygen migration through aluminum oxide and growth of an oxide film underneath the aluminum oxide. In addition, at least a part of the new-formed oxide appeared to be comprised of a mixture of aluminum, silicon, and oxygen.