High Concentration Of Chloride Ions Research Articles

Corrosion Effects on the Seismic Vulnerability Index of Reinforced Concrete Scholar Buildings

The Veracruz - Boca del Río metropolitan area in Mexico presents high temperatures and even high chloride ion concentrations, causing an aggressive environment with significant corrosion rates. Therefore, in reinforced concrete buildings in said area, their service life and integrity can compromise. Rapid Screening Methods (RSM) are used to determine their Seismic Vulnerability Index (SVI). The Benedetti-Petrini RSM can be used to determine the SVI of the corroded structures, adapting how the state of conservation is evaluated and weighted. To that end, the corrosion level and the crack width were correlated to estimate how their state of conservation can be deteriorated, reducing the service life. To test its usefulness, nine faculties, whose ages are close to 50 years, were analyzed, and the SVI of the original and modified methods were compared. Additionally, as expected, the buildings close to the coastline, and the faces exposed to wind direction, were the most damaged. The results indicate that the modified SVI provides rational decisions and improves the action management for each structure.

Heterogenous Iron Oxide Assemblages for Use in Catalytic Ozonation: Reactivity, Kinetics, and Reaction Mechanism.

Heterogeneous catalytic ozonation (HCO) has gained increasing attention as an effective process to remove refractory organic pollutants from industrial effluents. However, widespread application of HCO is still limited due to the typically low efficacy of catalysts used and matrix passivation effects. To this end, we prepared an Al2O3-supported Fe catalyst with high reactivity via a facile urea-based heterogeneous precipitation method. Due to the nonsintering nature of the preparation method, a heterogeneous catalytic layer comprised of γ-FeOOH and α-Fe2O3 is formed on the Al2O3 support (termed NS-Fe-Al2O3). On treatment of a real industrial effluent by HCO, the presence of NS-Fe-Al2O3 increased the removal of organics by ∼100% compared to that achieved with a control catalyst (i.e., α-Fe2O3/Al2O3 or γ-FeOOH/Al2O3) that was prepared by a conventional impregnation and calcination method. Furthermore, our results confirmed that the novel NS-Fe-Al2O3 catalyst demonstrated resistance to the inhibitory effect of high concentration of chloride and sulfate ions usually present in industrial effluent. A mathematical kinetic model was developed that adequately describes the mechanism of HCO process in the presence of NS-Fe-Al2O3. Overall, the results presented here provide valuable guidance for the synthesis of effective and robust catalysts that will facilitate the wider industrial application of HCO.

Corrosion potential of coated steel bar embedded in sea-water mixed mortar

Corrosion of embedded steel bars in concrete structures is the most impactful deterioration case in the world therefore many researchers and engineers are looking for the unknown mechanism related to the occurrence process, the effect of the damaged structures to its capacity and serviceability, and the intervention methods to control the rate of corrosion nowadays. One of the most prevalent liquid materials used in concrete is freshwater. However, the lack of freshwater for basic requirements in certain regions necessitates the adoption of an alternate material. Seawater, abundant in Indonesia, has the ability to substitute freshwater in concrete mixtures. However, its high concentration of chloride ions might raise the risk of corrosion in reinforced concrete structures. The laboratory experiment was proposed to find the empirical test result of the performance of corrosion prevention to the seawater mix RC structures. Three type of cements (PPC, PCC, and PPC-PCC mixture) were used as binder and two type of protection (steel coating and no coating) were applied in this research. One day after specimen casting, it were demolded and cured under water condition until 28 days. After that, the cylindrical and beams specimens were tested and the cubical specimens were exposed to three conditions (air-dry, wet, and dry-wet cycle) until a half-year and the half-cell potential test was conducted periodically every week. Based on the results, it demonstrated that the steel coating is the most suitable corrosion prevention method and PCC is recommended to maintain the corrosion potential stable to be passive.

Hydrochemical Evaluation of Groundwater Resources in Ngbo Areas, Ebonyi State, Southeast Nigeria.

The hydrochemical evaluation of groundwater resources of Ngbo Area have been carried out covering parts of Ohaukwu and Ebonyi LGAs of Ebonyi State. The area lies between latitudes 6025’N and 6030’N, and longitudes 8000’E and 8005’E. Geologically, the area is underlain by highly consolidated dark-grey and fissile- brown shales, limestone and mudstones belonging to the Albian Asu River Group. Ten (10) groundwater samples were collected for analysis using Standard sampling procedures. The result which was compared with the World Health Organization and Nigerian Standard shows that the mean concentration of the physical parameters such as pH (6.92), total dissolved solid (15.56), electrical conductivity (15.56), and total hardness (1.0mg/l) of the groundwater of the area are fresh (due to TDS < 1000 mg/l at temperature range of 270C to 300C), dominantly alkaline, moderately hard in some locations such as locations 7 (Umuezaka Ngbo), 9 (Hill Top Pri. Sch., Amoffia Ngbo) and 10 (Ndiulo Umusoke Amoffia Ngbo), possibly due to bicarbonate (HCO3–) concentrations of 340mg/l, 279mg/l, and 335mg/l, and were within the permissible limits for drinking, domestic, industrial and agricultural purposes. High concentration of chloride ions in some of the samples was indicated. This could be attributed to the presence of igneous rocks and the leaching of sewage effluents down to the groundwater system. The dominant order of cations and anions chemistry for most of the analyzed groundwater samples is Ca2+>Mg2+>Na+>K+ and Cl–>HCO3– >SO42-> and NO3– respectively. This is a reflection of high carbonates in the rocks. Proper sewage disposal should be upheld in the area.

Prospective of the LDI MS to characterization the corrosion products of silver-copper alloys on an example of the Ag-Cu-X (X- Zn, Pd, In) system

This work presents the perspective of applying the laser desorption/ionization mass spectrometry (LDI MS) for characterization the anode film of the Ag60Cu26Zn14, Ag58.5Cu31.5Pd10, and Ag63Cu27In10 alloys (at high concentrations of chloride ions in solutions). The reference LDI mass spectra of anode films of pure Ag and Cu have been used for the identification of product corrosion. Knowing the clusters detected in the reference spectra lead to the facilitating identification of the LDI mass spectrum of the sample and reduces the analysis time. The LDI MS analysis of these alloys revealed that the predominant corrosion product are AgCl (from AgnCln+1−/+, n = 1–3), and CuCl (from “superhalogen” CumCln− clusters, m = 1–2, n = 2–6); it also revealed Cu2(OH)3Cl (from Cu2(OH)(H2O)2+) and Cu2O (from Cu(H2O)+, Cu2O doped with chlorine). These results are in accordance with the X-ray diffraction and Raman analysis. The LDI MS spectra of alloys contain the additional peaks formed due to the mutual influences of different metals in the alloys (AgCuCl3− (AgCl-CuCl2−), AgCu2Cl4− (AgCl-CuCl-CuCl2−), and Ag2CuCl4− (AgCl-AgCl-CuCl−), which is consistent with the identified corrosion products. It should be noted that the LDI MS suggest the presence of CuCl2, which can be interpreted as the corrosion products retained in the porous films of alloys, and not detected by the other methods due to a small amount. The future theoretical and experimental studies of metal clusters, significant for metallurgy, can contribute that the LDI MS is becoming a powerful analytical tool for characterization the metal surfaces.

Elimination of pesticide from high salinity wastewater by electrochlorination process: Active chlorine species and scale-up performance

Active chlorine species-mediated electrochemical process is a promising strategy for refractory pollutants and ammonia removal in high salinity organic wastewater. Herein, we constructed an electrochlorination (E-Cl) process with the help of the high concentration of chloride ions (Cl−) in the wastewater to realize the efficient treatment of pesticide wastewater. The E-Cl process exhibited excellent chemical oxygen demand (COD, 86.43%) and atrazine (ATZ, 98.67%) removal efficiency for the actual pesticide wastewater since active chlorine species, including free chlorine and reactive chlorine species (RCS), and hydroxyl radical (•OH) were all in-situ produced during the electrolysis process. The quenching experiments indicated that the free chlorine was the primary oxidizing substance for the decomposition of ATZ, and the RCS and •OH mainly enhanced the mineralization of intermediate products. In addition, the inhibition mechanism of different background substances in the E-Cl process was different. The toxicity test and three-dimensional fluorescence spectrum all proved that the E-Cl process could effectively remove ATZ and other organic matter from the actual pesticide wastewater. Finally, an E-Cl pilot reactor was designed and the pilot-scale experiments showed that the COD and NH4+-N of the actual pesticide wastewater after the treatment of the E-Cl process were < 50 mg/L and < 1.5 mg/L, and the energy consumption (EC) was ∼4.98 kWh/m3. The successful treatment of actual pesticide wastewater by the E-Cl process suggests that this is a promising method for treating organic pollutants and ammonia under highly salinity conditions.

Performance of drainage geocomposites applied as capillary break layers

The phenomenon of capillary rise can cause water rise up 2-3m above the high water table within the soil. Due to this effect the shear strength of fine-graded soil is decreased, or it can damage decorative floorings, paved areas, concrete and different manmade structures. Furthermore, in arid regions the ground water is often saline with a high concentration of chloride ions, which can be harmful to vegetation. The traditional methods to solve the above mentioned problems with breaking the capillary rise can be the use of free draining granular soil with very low fines contents, usually with 30 to 50 cm thickness. One of the effective capillary break methods is creating an air void between the soil layers with the help of drainage geocomposites therefore capillary rise of water is prevented. This paper presents the research work of the above described capillary break phenomenon with different types of geocomposite drainage layers in laboratory controlled conditions.

Chloride-Enhanced Removal of Ammonia Nitrogen and Organic Matter from Landfill Leachate by a Microwave/Peroxymonosulfate System

Landfill leachate contains not only high concentrations of refractory organic matter and ammonia nitrogen, but also high concentrations of chloride ions (Cl−). The modification of reactive species of the peroxymonosulfate (PMS) oxidation system by Cl− and its priority sequence for the removal of NH4+-N and organic matter from landfill leachate remain unclear. This study investigated the removal characteristics of NH4+-N and organic matter in the microwave (MW)/PMS system with high Cl− content. The results show that increasing Cl− concentration significantly improves the production of hypochlorous acid (HOCl) in the MW/PMS system under acidic conditions, and that the thermal and non-thermal effects of MW irradiation have an important influence on the HOCl produced by PMS activation. The maximum cumulative concentration of HOCl was 748.24 μM after a reaction time of 2 min. The formation paths of HOCl are (i) SO4•− formed by the MW/PMS system interacting with Cl− and HO•, and (ii) the nucleophilic addition reaction of PMS and Cl−. Moreover, the high concentration of HOCl produced by the system can not only remove NH4+-N in situ, but also interact with PMS to continuously generate Cl• as an oxidant to participate in the reaction with pollutants (e.g., NH4+-N and organic matter). Common aqueous substances (e.g., CO32−, HCO3−, NO3−, and humic acid) in landfill leachate will compete with NH4+-N for reactive species in the system, and will thereby inhibit its removal to a certain extent. It was found that when NH4+-N and leachate DOM co-exist in landfill leachates, they would compete for reactive species, and that humic acid-like matter was preferentially removed, leading to the retention of fulvic acid-like matter. It is hoped that this study will provide theoretical support for the design and optimization of methods for removing NH4+-N and organic matter from landfill leachate with high chloride ion content.

Removal characteristics of ammonia nitrogen and refractory organic matter in waste leachate by Co2+/peroxymonosulfate process at high chloride ion concentration

Landfill leachate contains high concentrations of refractory organic matter (ROM), ammonia nitrogen (NH4+), and chlorine ion (Cl–). With efficient ROM removal being the focus of advanced oxidation processes, there is an urgent need to clarify the role of high Cl– concentration on reactive species and preferential reactivity towards coexistent ROM and NH4+. This study investigated the removal characteristics of ROM and NH4+ using a Co2+/peroxymonosulfate (Co2+/PMS) process with high Cl– concentration. The results showed that the system produced large amount of hypochlorous acid (HOCl), with a maximum accumulated HOCl concentration reaching 2.78 mM at Co2+, PMS, and Cl– concentrations of 105 μM, 10 mM, and 17 mM, respectively. The differences in Cl–-to-PMS molar ratios altered HOCl formation pathway, and both Co3+ and SO4•− played important roles in HOCl generation. Although the initial concentrations of PMS, Co2+, and Cl– were proportional to the cumulative HOCl concentration, increasing pH significantly inhibited HOCl formation. The coexisting anions commonly found in waste leachate (i.e., CO32−, HCO3−, and NO3−) promoted HOCl production to some extent, but both NH4+ and dissolved organic matter (humic acid and amino acid complex) severely depleted the formed HOCl. Analysis of the removal characteristics of NH4+ and ROM in co-occurrence in actual waste leachate at high Cl– concentrations revealed that NH4+ and ROM competed for HOCl, and preferential removal of humic-like substances led to retention of fulvic-like substances. These results provide theoretical support for the design and optimization of methods for NH4+ and ROM removal from waste leachate containing high Cl– content.

Evaluation of Groundwater Quality by Water Quality Index During Successive Periodic Intervals in the Selected Villages of Gara Mandal of Srikakulam District in Andhra Pradesh

The quality of groundwater is assessed using the Water Quality Index method and it is pertinently helpful to transfer the complex data into usable data. In this research study the WQI values have been estimated for each water sample (in total, 66 samples have been collected) based on 9 water quality parameters at periodic intervals in May 2015, 2016 and 2017 in the villages of Gara Mandal of Srikakulam District in Andhra Pradesh. The overall results disclosed that 50-54% of the groundwater samples (WQI lies between 100-200) showed poor quality and 10-13% of water samples (WQI lies between 200-300) showed very poor quality in successive periodic intervals. An assessment of measured physicochemical parameters of 66 sample sites has shown that the majority of the groundwater samples have a high concentration of calcium, magnesium, sodium, chloride and sulfate ions beyond the desirable limits of BIS and WHO standards. Correlation matrix show a strong positive correlation existing between the calcium, magnesium, sodium, chloride and sulfate ions pointing out that groundwater in this region has been contaminated more by these components due to anthropogenic activities and over-exploitation. Hence, in the study region, suitable treatment of water is necessary before consumption, this is because maximum parts of the sampling points have a high WQI value.

Prediction of Concrete Compressive Strength in Saline Soil Environments.

Saline soil in Western China contains high concentrations of chloride ions, sulfate ions, and other corrosive ions, and the performance of concrete will substantially deteriorate from exposure to this environment. Therefore, it is of great significance to study and predict the concrete compressive strength in saline soil environments. In this paper, the effects of corrosion on concrete were analyzed from the aspects of surface damage, damage depth, and X-ray diffraction (XRD) of the corrosion products. The effects of corrosion were quantified by damage depth and corrosion depth. Then, considering the corrosion effects combined with Fick’s diffusion law, a time-dependent model of concrete compressive strength and a time-dependent model of damage depth were established. The results show that the deterioration of concrete gradually developed from the surface to the interior, and that the interface of the concrete specimen was equivalent to three parts: a failure zone, a filling zone, and an undisturbed zone. The results also showed that the time-varying model of concrete compressive strength proposed by the author was fully applicable, with an error of less than five percent. The service life of concrete predicted by the damage depth was found to be about 253 months (21.1 years), and the service life predicted by the time-varying compressive strength model was about 187 months (15.6 years). Both prediction results were far less than the normal concrete service life of 50 years. In addition, the long-term compressive strength of the corroded concrete was about 90% of that of the noncorroded concrete, which did not deteriorate with the corrosion time.

Influence of sea salt on the interfacial adhesion of bitumen–aggregate systems by molecular dynamics simulation

• Sea salt damaged bitumen’s original colloidal structure by disaggregating asphaltenes. • Saturates played the major role by most extensively diffusing to the surface of silica. • SARA fractions’ redistribution was driven by water with ions only acting as catalysts. • Number of SARA fractions in model decreased the adhesion energy in all environments. • Spatiotemporal distribution of SARA fractions at the interface determined the adhesion. This research investigated the influence of sea salt on the adhesion properties of bitumen–aggregate systems by molecular dynamics simulations in order to fundamentally understand the mechanism of damage in the seawater environment. The seawater environment was simulated by high concentrations of chloride, sodium, sulfate, magnesium, and calcium ions in water. Bitumen was represented by 3-, 4-, and 12-component models using the COMPASS force field, while the bitumen–seawater–aggregate interfacial model was discontinued by a vacuum layer of 60 Å in thickness. The results demonstrated that the presence of seawater affected the adhesion by facilitating the molecular migrations of bitumen components and by weakening the agglomeration of asphaltene. Consequently, this gradually damaged the colloidal structure of bitumen in the interfacial zone. Saturates played a dominant role in the adhesion in the seawater environment because they were the most likely to diffuse away from the silica surface. Besides the composition of bitumen, the spatiotemporal distribution of its components in the region of the interface was also identified as extremely important for the interpretation of the intrinsic factors which control the adhesion behaviour of thesesystems.

Electrochemical redox treatment of denitrification in coastal secondary effluent using Ti/IrO2 anode

In northern coastal industrial park, inlet of the wastewater treatment plant (WWTP) had the characteristics of low carbon source and high chloride ion concentration, which resulted in its poor biodegradability. In this case, the experiment explored an electrochemistral method to remove nitrogen. Cathodic potential, Ti/IrO2 was confirmed as the anode and − 1.6 V was taken as the potential in order to remove nitrate-N. The findings include: when the initial chloride ion was 2000 and 3000 mg/L, the effect on the removal difference of nitrogen was slight. When the electrolysis time was 60 min, ammonia-N was removed completely, nitrite-N concentration kept 1 mg/L approximately. The ammonia-N removal efficiency went up with the increasing cathodic potential, and was completely removed in different water samples, but nitrate-N removal showed an opposite result. The production amount of nitrite-N was the least at − 1.6 V. As the pH increased, ammonia-N and nitrate-N’s removal efficiency went up first and then down, the removal effect was the best at pH being 9, Nitrite-N was less influenced by pH. After optimizing the raw water sample, Nitrate-N and TN removal efficiency were significantly increased, but the nitrite-N almost kept constant.

Use of Alternative Water Resources in Copper Leaching Processes in Chilean Mining Industry—A Review

Due to the significant growth of the world population, the accelerated growth of economic industries in various countries, and improved living conditions, freshwater consumption has increased dramatically and is currently under critical pressure. Its good use and rationing are essential. Even though mining is an industry that consumes much less water than other industries, such as agriculture, surrounding communities are constantly questioned. This occurs mainly because mining deposits are generally found in arid areas where freshwater is scarce, forcing government authorities to regulate water use in mining processes more severely. Faced with this scenario, the mining industry has innovated the use of seawater and wastewater from processes for its production processes. In addition, various projects are under development to construct desalination plants and water impulsion systems of the sea; therefore, it is expected that seawater and/or wastewater in mining will continue to grow in the coming years. Among the main challenges faced in the use of these water resources in mining is: (i) the close relationship that exists between the use of seawater and energy consumption, transferring the problem of water scarcity to a problem of energy cost overruns; (ii) generation of greater integration between the use of water and sustainable energy; and (iii) brine management is economically expensive and technically challenging and, therefore, most desalination plants discharge untreated brine directly into the sea, causing an environmental impact. On the other hand, regarding the use of these water resources in leaching processes, there are very positive results for the dissolution of copper from sulfide minerals, where the wastewater from desalination plants presents better results than seawater due to its higher concentration of chloride ions, allowing it to work at higher redox potential values in order to increase copper dissolution. This manuscript is a bibliographic review in which finally, it is concluded that it is feasible to incorporate wastewater from water desalination plants in heap leaching processes for copper sulfide ores, as long as the cost of transfer from water desalination plants to mining sites can be supported.

High Selectivity Electrocatalysts for Oxygen Evolution Reaction and Anti-Chlorine Corrosion Strategies in Seawater Splitting

Seawater is one of the most abundant and clean hydrogen atom resources on our planet, so hydrogen production from seawater splitting has notable advantages. Direct electrolysis of seawater would not be in competition with growing demands for pure water. Using green electricity generated from renewable sources (e.g., solar, tidal, and wind energies), the direct electrolytic splitting of seawater into hydrogen and oxygen is a potentially attractive technology under the framework of carbon-neutral energy production. High selectivity and efficiency, as well as stable electrocatalysts, are prerequisites to facilitate the practical applications of seawater splitting. Even though the oxygen evolution reaction (OER) is thermodynamically favorable, the most desirable reaction process, the four-electron reaction, exhibits a high energy barrier. Furthermore, due to the presence of a high concentration of chloride ions (Cl−) in seawater, chlorine evolution reactions involving two electrons are more competitive. Therefore, intensive research efforts have been devoted to optimizing the design and construction of highly efficient and anticorrosive OER electrocatalysts. Based on this, in this review, we summarize the progress of recent research in advanced electrocatalysts for seawater splitting, with an emphasis on their remarkable OER selectivity and distinguished anti-chlorine corrosion performance, including the recent progress in seawater OER electrocatalysts with their corresponding optimized strategies. The future perspectives for the development of seawater-splitting electrocatalysts are also demonstrated.

Synergistic Effect of Different NaCl Concentrations on the Initial Corrosion of Q235 Steel under a Simulated SO2 Environment

AbstractThe synergistic effect of chloride ions and industrial corrosive gases in the atmosphere intensifies metal corrosion. Therefore, the study of this corrosive behavior and its effects on metals in complex environments is crucial. In this study, the wet/dry cyclic corrosion test, under a constant deposited salt, was used to simulate atmospheric corrosion conditions. In addition, the methods of corrosion weight gain, dynamic potential polarization curves, electrochemical impedance spectroscopy, and other analyses were used to explore the mechanism and law of Q235 steel with different corrosion times in different coastal‐industrial atmospheric environments. The corrosion pattern of Q235 steel and the composition of the rust layer were further investigated through X‐Ray Diffractometer analysis and Scanning Electron Microscope observations. The results show that the content of Fe3O4 decreases at higher chloride ion concentrations and the content of α‐FeOOH increases in later stages of corrosion.

Evaluation of Physicochemical Characteristics and Carbonate Equilibria System of the New Calabar River, Choba, Rivers State, Nigeria

Carbonate equilibrium helps to critically determine the degree or level of pollution and its possible source. In this study the physicochemical properties and carbonate equilibria system of the New Calabar River, Choba, Rivers State, Nigeria was evaluated using standard techniques by analyzing the pH, total dissolved solid, bicarbonate ion, sulphate ion, chloride ion, total alkalinity and total hardness of five samples collected from strategic points along the River. Data obtained show that the pH ranged 5.93-6.33, while TDS values varied from 4770mg/l to 5280mg/l. The total alkalinity of the sample 1, sample 2, sample 3, sample 4 and sample 5 analyzed and their results are 70mg/l, 68 mg/l, 66 mg/l, 73 mg/l and 60.5 mg/l respectively. The total hardness of sample 1, sample 2, sample 3, sample 4 and sample 5 collected from the New Calabar River and the results are 913mg/l, 904 mg/l, 942 mg/l, 933 mg/l and 939 mg/l. The sulphate ion concentration for sample 1, sample 2, sample 3, sample 4 and sample 5 are 519.20mg/l, 510.5mg/l, 552mg/l, 543mg/l and 549.00mg/l, while the Chloride concentration varied from 3390.5 mg/l to 4,802 mg/l mg/l. Result indicated that all physiochemical parameters apart from total alkalinity was not within the WHO guidelines or standard and the river shows presence of weak acid deposits but very high concentration of chloride ion which indicates higher degree of organic pollution and also acidic in nature. Thus, the river poses a health risk to the rural communities who rely primarily on them as the only source of domestic water supply.

Laser Additively Manufactured Iron-Based Biocomposite: Microstructure, Degradation, and In Vitro Cell Behavior.

A too slow degradation of iron (Fe) limits its orthopedic application. In this study, calcium chloride (CaCl2) was incorporated into a Fe-based biocomposite fabricated by laser additive manufacturing, with an aim to accelerate the degradation. It was found that CaCl2 with strong water absorptivity improved the hydrophilicity of the Fe matrix and thereby promoted the invasion of corrosive solution. On the other hand, CaCl2 could rapidly dissolve once contacting the solution and release massive chloride ion. Interestingly, the local high concentration of chloride ion effectively destroyed the corrosion product layer due to its strong erosion ability. As a result, the corrosion product layer covered on the Fe/CaCl2 matrix exhibited an extremely porous structure, thus exhibiting a significantly reduced corrosion resistance. Besides, in vivo cell testing proved that the Fe/CaCl2 biocomposite also showed favorable cytocompatibility.

Same site, different corrosion phenomena caused by chloride: The effect of the archaeological context on bronzes from Sujialong Cemetery, China

The corrosion of archaeological bronzes is a complex process, and different corrosion phenomena can occur even within the same site, while previous studies paid little attention. Different corrosion phenomena can be observed on bronzes unearthed from Sujialong Cemetery, Hubei, China; in particular, some bronzes exhibit severe bronze disease, which is an uncommon phenomenon in Hubei bronzes. Multiple analysis methods were used to identify the corrosion products on the bronzes and to clarify the corrosion mechanisms. The results showed that the different corrosion phenomena were associated with the tomb microenvironment in different areas of the cemetery, which was confirmed by a spatial analysis of the whole cemetery; the outbreak of bronze disease was closely related to the presence of high chloride ion concentrations in the tomb environment and poor preservation conditions after excavation. The different corrosion phenomena are related to the archaeological contexts of the bronzes (especially microenvironments), which have been investigated only superficially in the past.

Degradation of chloroaniline in chemical wastewater by ionizing radiation technology: Degradation mechanism and toxicity evaluation

Chloroaniline is a typical organic pollutant in chemical wastewater, which cannot be effectively removed in conventional wastewater treatment processes. In this study, ionizing radiation was used as advanced treatment process to degrade 2-chloroaniline (2-CA). The results showed that 10 mg/l of 2-CA could be completely degraded at 1 kGy. The required dose for completely degrading 2-CA by radiation increased when its initial concentration increased. Solution pH affected 2-CA degradation by changing the radiation-chemical yield of reactive species. Chloride ions (10 and 100 mM) had not obvious influence on 2-CA degradation. Hydrogen radicals, hydrated electrons and hydroxyl radicals, all contributed to the degradation of 2-CA, but with different degradation mechanisms. Hydrogen radicals and hydrated electrons could initiate reductive dechlorination of 2-CA, while hydroxyl radicals can degrade 2-CA by hydroxylation. 6-amino-1,4-cyclohexadiene and chlorobenzene were the main intermediate products of 2-CA degradation in the hydrogen radicals or hydrated electrons dominant process; while o-hydroxyaniline and nitroso-chlorobenzene were the main intermediate products in the hydroxyl radicals dominant process. The solution toxicity after radiation treatment varied with the initial concentration of 2-CA and the absorbed dose. In the actual chemical wastewater, 2-CA can be effectively removed by radiation, even in the presence of high concentration of chloride ions (about 2800 mg/l). The solution toxicity of actual wastewater decreased with the increase of adsorbed dose. This study provided an insight into the 2-CA degradation by radiation, and demonstrated that radiation could be an alternative option for the treatment of chloroaniline-containing chemical wastewater.