A comparative study of treatment of simulated wastewater containing Reactive Red 195 using zero-valent iron/activated carbon (ZVI/AC), microwave discharge electrodeless lamp/sodium hypochlorite (MDEL/NaCIO) and th...A comparative study of treatment of simulated wastewater containing Reactive Red 195 using zero-valent iron/activated carbon (ZVI/AC), microwave discharge electrodeless lamp/sodium hypochlorite (MDEL/NaCIO) and the combination of ZVI/AC- MDEL/NaCIO was conducted. The preliminary results showed the two steps method of ZVI/AC-MDEL/NaCIO had much higher degradation efficiency than both single steps. The final color removal percentage was nearly up to 100% and the chemical oxygen demand reduction percentage was up to approximately 82%. The effects of operational parameters, including initial pH value of simulated wastewater, ZVI/AC ratio and particle size of ZVI were also investigated. In addition, from the discussion of synergistic effect between ZVI/AC and MEDL/NaCIO, we found that in the ZVI/AC-MEDL/NaCIO process, ZVI/AC could break the azo bond firstly and then MEDLfNaCIO degraded the aromatic amine products effectively. Reversing the order would reduce the degradation efficiency.展开更多
The influencing factors and kinetics of oxidative degradation of ammonia nitrogen in high salinity wastewater by sodium hypochlorite oxidation( Na Cl O) were studied. The results showed that the degradation process of...The influencing factors and kinetics of oxidative degradation of ammonia nitrogen in high salinity wastewater by sodium hypochlorite oxidation( Na Cl O) were studied. The results showed that the degradation process of ammonia nitrogen by sodium hypochlorite accorded with a pseudo first-order kinetics model,and the influencing factors included Na Cl O dosage,initial concentration of ammonia nitrogen,salinity,temperature,and so on. When Na Cl O dosage was 0. 6%( MCl∶ MN= 13. 76),the reaction rate constant was up to 0. 015 75 min^(-1). The higher the initial concentration of ammonia nitrogen was,the worse the effect of oxidation reaction was. When the initial concentration did not exceed 45 mg/L,the effect on oxidation reaction rate constant increased with the increase of the initial concentration. Low salinity had no effect on ammonia nitrogen oxidation.When salinity was higher than 2. 0%,the inhibition effect on ammonia nitrogen oxidation would increase,and the reaction rate constant decreased obviously with the increase of salinity. The improvement of reaction temperature was beneficial to ammonia oxidation degradation. As temperature increased from 10 to 35 ℃,the reaction rate constant rose from 0. 00188 to 0. 01043 min^(-1).展开更多
We developed a novel rapid hygrothermal pasteurization (RHP) method using saturated water vapor with a dew point of 100℃. The aim of this paper is to compare the effect of RHP treatment versus conventional sodium hyp...We developed a novel rapid hygrothermal pasteurization (RHP) method using saturated water vapor with a dew point of 100℃. The aim of this paper is to compare the effect of RHP treatment versus conventional sodium hypochlorite (NaClO) treatments on inactivation of natural mesophilic bacteria and quality attributes on fruits and vegetables. The RHP treatment was performed within a second by free-falling samples (cabbage, cucumber, carrot, bell pepper, pineapple and melon) through cylindrical processing chamber filled with steam. NaClO treatment was performed by washing samples with NaClO solution (100 mg/mL of free chlorine (pH 7), for 1 min). The RHP treatment showed a significantly higher inactivation effect than NaClO treatment on all tested samples. The RHP treatment had a slightly larger influence on color and vitamin C content than NaClO treatment in cabbage. Furthermore, the effects of treatment time and operated temperature were also determined using microbial model system. Elongation of treatment time did not significantly increase the microbial inactivation effect. Lowering of operated temperature by mixing air into steam tended to decrease the inactivation effect. From these results, RHP treatment could be used as an alternative method for decontaminating microorganisms on fruits and vegetables, except on leafy vegetable. In addition, it is suggested that microbial inactivation by RHP treatment was achieved through the initial condensation stage of water vapor on sample surface. By contrast, interfusion of air disturbed the effective condensation of water vapor.展开更多
This study evaluated the effects of sodium hypochlorite(NaOCl) with different concentrations and exposure time on the structural, compositional and mechanical properties of human dentin in vitro. Sixty dentin slabs ...This study evaluated the effects of sodium hypochlorite(NaOCl) with different concentrations and exposure time on the structural, compositional and mechanical properties of human dentin in vitro. Sixty dentin slabs were obtained from freshly extracted premolars, randomly distributed into four groups(n=15), and treated with 1%, 5%, 10% NaOCl and distilled water(control group), respectively, for a total of 60 min. Attenuated total reflection infrared(ATR-IR) spectroscopy, Raman spectroscopy and X-ray diffraction(XRD) were carried out before, 10 min and 60 min after the treatment. Scanning electron microscopy(SEM) and flexural strength test were conducted as well. The results showed that dentins experienced morphological alterations in the NaOCl groups, but not in the control group. Two-way repeated-measures analysis of variance revealed that the carbonate:mineral ratio(C:M), Raman relative intensity(RRI), a-axis, c-axis length and full width at half maximum(FWHM) with the increase of time and concentration in the NaOCl groups were not significantly different from those in the control group(P〉0.05). Nevertheless, the mineral:matrix ratio(M:M) increased and the flexural strength declined with the increase of concentration and the extension of time in the NaOCl groups(P〈0.05). Additionally, it was found that the M:M and the flexural strength remained unchanged after 1% NaOCl treatment(P〉0.05), and the morphology changes were unnoticeable within 10 min in 1% NaOCl group. These results indicated that NaOCl has no significant effects on the inorganic mineral of human dentin; but it undermines and eliminates the organic content concentration-and time-dependently, which in turn influences the flexural strength and toughness of dentins. In addition, an irrigation of 1% NaOCl within 10 min can minimize the effects of NaOCl on the structural and mechanical properties of dentin during root canal treatment.展开更多
Two modified electrodes (Pb/PbO2 and C/PbO2) were prepared by electrodepositing a lead oxide layer on lead and carbon sub- strates. These modified electrodes were used as anodes for the generation of sodium hypochlo...Two modified electrodes (Pb/PbO2 and C/PbO2) were prepared by electrodepositing a lead oxide layer on lead and carbon sub- strates. These modified electrodes were used as anodes for the generation of sodium hypochlorite (NaOC1) from sodium chloride solution. Different operating conditions and factors affecting the treatment process of NaOC1 generation, including current density, pH values, con- ductive electrolytes, and electrolysis time, were studied and optimized. By comparison the C/PbO2 electrode shows a higher efficiency than the Pb/PbO2 electrode for the generation of NaOC1.展开更多
Introduction: “RC-Prep”, a chemo-mechanical preparation for root canals, includes EDTA and urea peroxide as ingredients. For lubrication and its chelating effect, RC-Prep is useful as an adjunct in root canal enlarg...Introduction: “RC-Prep”, a chemo-mechanical preparation for root canals, includes EDTA and urea peroxide as ingredients. For lubrication and its chelating effect, RC-Prep is useful as an adjunct in root canal enlargement. Furthermore, its cleaning action, due to its foaming properties in combi-nation with sodium hypochlorite, can be useful in root canal treatment in many situations. Methods: In a case of upper gingiva swelling, we used sodium hypochlorite with RC-Prep in the treatment of an infected root canal of the left maxillary premolar at the first visit. Within 2 min after use, the patient’s face became swollen. We kept the root canal open, and conducted a CT scan to investigate. Results: We diagnosed subcutaneous emphysema and prescribed 1 week of pain killers and antibiotics. The pain and swelling in the face finally resolved at 11 days after the incident. Conclusions: The cause of the emphysema was considered to have been the use of a sodium hypo-chlorite solution after using RC-Prep for an opened root apex.展开更多
Sodium hypochlorite (NaOCl) or bleach, found in effluent from wastewater treatment plants, can act as an environmental toxin. The sea urchin Arbacia punctulata is a common subject of embryological toxicity tests due t...Sodium hypochlorite (NaOCl) or bleach, found in effluent from wastewater treatment plants, can act as an environmental toxin. The sea urchin Arbacia punctulata is a common subject of embryological toxicity tests due to its sensitivity to environmental pollutants. Using concentrations of NaOCl that mimic those found in treated wastewater (0.11 ppm, 0.06 ppm, and 0.03 ppm) we observed minimal affects on early larval development, though most larvae took longer to develop at higher NaOCl concentration. There was a significant difference in the percentage of non-normal plutei based on concentration (P = 0.038) and significant interaction between the percent of each morphology and NaOCl concentration (P = 0.0027). The most significant change in non-normal plutei was in the retarded (shortened skeletal rods) malformation which increased in frequency with NaOCl concentration (P = 0.001). There was a significant reduction in skeletal length in both normal and retarded plutei (P < 0.05) as NaOCl increased.展开更多
5.1% of sodium hypochlorite (NaOCl) mixed with 2% of chlorhexidine (CHX) forms a brown precipitate that corresponds to para-chloroaniline (PCA), whether PCA is formed after the combination of NaOCl, CHX, and ethylened...5.1% of sodium hypochlorite (NaOCl) mixed with 2% of chlorhexidine (CHX) forms a brown precipitate that corresponds to para-chloroaniline (PCA), whether PCA is formed after the combination of NaOCl, CHX, and ethylenediaminetetraacetic acid (EDTA) by means of electron impact (high resolution and interlaced scanning) and ionization by fast atom bombardment (FAB), was analyzed. The brown precipitate, showed signals 127 and 153 Da, corresponding to p-chloroaniline and p-chlorophenyl isocyanate, respectively. These results were analyzed and compared with signals from the interlaced scanning program and confirmed with high resolution mass spectrometry analysis and compared with the NIST database. The mass spectra of this precipitated after different days confirmed the evolution of byproducts with the presence of a peak m/z = 127, due to the decrease of the fragment m/z = 153, which disappeared after 180 days. A blue and a white precipitate were observed by the addition of CHX (2%) with or without polyethylene glycol, respectively, EDTA (17%) and NaOCl (5.1%) precipitates contain chlorhexidine (m/z = 505), but no PCA was detected. We confirmed that PCA is not formed directly as a byproduct of CHX oxidation, but through the formation of the para-chlorophenyl isocyanate intermediate, which degrades slowly to PCA.展开更多
In recent years,various methods for detecting exogenous and endogenous hypochlorite have been studied,considering its essential role as a biomolecule.However,the existing technologies still pose obstacles such as thei...In recent years,various methods for detecting exogenous and endogenous hypochlorite have been studied,considering its essential role as a biomolecule.However,the existing technologies still pose obstacles such as their invasiveness,high costs,and complicated operation.In the current study,we developed a glow-type chemiluminescent probe,hypochlorite chemiluminescence probe(HCCL)-1,based on the scaffold of Schaap's 1,2-dioxetane luminophores.To better explore the physiological and pathological functions of hypochlorite,we modified the luminophore scaffold of HCCL-1 to develop several probes,including HCCL-2,HCCL-3,and HCCL-4,which amplify the response signal of hypochlorite.By comparing the luminescent intensities of the four probes using the IVIS®system,we determined that HCCL-2 with a limit of detection of 0.166 mM has enhanced sensitivity and selectivity for tracking hypochlorite both in vitro and in vivo.展开更多
The majority of the refractory gold and silver occurs in occlusion in sulphides, then precious metal dissolution is possible by first oxidizing auriferous sulfide concentrate using sodium hypochlorite-sodium-hydroxide...The majority of the refractory gold and silver occurs in occlusion in sulphides, then precious metal dissolution is possible by first oxidizing auriferous sulfide concentrate using sodium hypochlorite-sodium-hydroxide solution followed of pressure cyanidation of the oxidized concentrate, for the extraction of precious metals. This process was conducted and evaluated under cyanide and oxygen pressure. This versatile approach offers many advantages, including low temperatures, low pressure and less costly materials of construction than conventional pressure oxidation. In this study, the effect of oxygen pressure, concentration of sodium hypochlorite, temperature, and initial pH, in precious metals recovery and As removal were evaluated using a 24 factorial design. Characterization of the ores showed that pyrite and arsenopyrite were the main minerals present on the concentrate. The best results for gold extraction were obtained with oxygen pressure of 80 psi, 10% (w/w) sodium hypochlorite, temperature of 80℃, at pH = 13, and a constant stirring speed of 600 rpm. These conditions allowed an approximated 60% of gold and 90% of silver extractions in 1 hr.展开更多
To investigate the structural features and provide an alternative method for high value-added utilization of coal, Lingwu coal was first extracted with organic solvent at room temperature. Then its extraction residue ...To investigate the structural features and provide an alternative method for high value-added utilization of coal, Lingwu coal was first extracted with organic solvent at room temperature. Then its extraction residue was oxidized in aqueous sodium hypochlorite(ASHC) under mild conditions. The effects of oxidation conditions, such as temperature, reaction time, the ratio of Lingwu coal extraction residue(LCER, g) to ASHC(m L) and p H value, on the product distributions and compositions were investigated. The results of gas chromatography/mass spectrometry(GC/MS) suggested that 53 kinds of methyl esterified products were detected in total, and benzene carboxylic acids were the main oxidation products, while chloro-substituted benzene carboxylic acids were the main by-products. Higher yield and fewer kinds of organic acids could be obtained at lower p H value, especially for the main objective product, benzene carboxylic acids.展开更多
Sodium hypochlorite has significant potential as a sanitation solution in hard-to-reach areas.Few studies have investigated the optimal electrolysis parameters for its production with volumes greater than 1o L.This st...Sodium hypochlorite has significant potential as a sanitation solution in hard-to-reach areas.Few studies have investigated the optimal electrolysis parameters for its production with volumes greater than 1o L.This study evaluated sodium hypochlorite production through electrolysis in a 22-L prototype and identified the optimal operating parameters.Tests were performed using graphite electrodes with areas of 68.4 cm²at the laboratory scale and 1865.0 cm?at the prototype scale.A design for experiments with different operating times,chloride concentrations,and electric current intensities was developed.The optimal operating time,sodium chloride concentration,and current intensity at the laboratory scale were 120 min,150 g of chloride per liter,and 3 A,respectively,leading to the production of 5.02 g/L of the disinfectant with an energy efficiency of 12.21 mg of Cl2 per kilojoule.At the prototype scale,the maximum sodium hypochlorite concentration of 3.99 g of chloride per liter was achieved with an operating time of 120 min,a sodium chloride concentration of 100 g of chloride per liter,and a current intensity of 70 A,reaching an energy efficiency of 42.56 mg of Cl2 per kilojoule.In addition,this study evaluated the influences of the chloride concentration,current intensity,and operating time on the production of sodium hypochlorite at the two scales,and formulated the equations showing the trends of sodium hypochlorite production and energy efficiency in the electrochemical systems.The 22-L prototype model for production of this oxidizing substance is promising for disinfection of large volumes of water in areas that are difficult to access.展开更多
基金supported by the Major Projects on Control and Rectification of Water Body Pollution (Water Special Project) (No.2009ZX07010-001,2008ZX07526-001)the National Basic Research Program (973) of China (No.2008CB418201)
文摘A comparative study of treatment of simulated wastewater containing Reactive Red 195 using zero-valent iron/activated carbon (ZVI/AC), microwave discharge electrodeless lamp/sodium hypochlorite (MDEL/NaCIO) and the combination of ZVI/AC- MDEL/NaCIO was conducted. The preliminary results showed the two steps method of ZVI/AC-MDEL/NaCIO had much higher degradation efficiency than both single steps. The final color removal percentage was nearly up to 100% and the chemical oxygen demand reduction percentage was up to approximately 82%. The effects of operational parameters, including initial pH value of simulated wastewater, ZVI/AC ratio and particle size of ZVI were also investigated. In addition, from the discussion of synergistic effect between ZVI/AC and MEDL/NaCIO, we found that in the ZVI/AC-MEDL/NaCIO process, ZVI/AC could break the azo bond firstly and then MEDLfNaCIO degraded the aromatic amine products effectively. Reversing the order would reduce the degradation efficiency.
基金Supported by Project for Achievement Transformation of High and New Technology in Shanghai City(201405267)
文摘The influencing factors and kinetics of oxidative degradation of ammonia nitrogen in high salinity wastewater by sodium hypochlorite oxidation( Na Cl O) were studied. The results showed that the degradation process of ammonia nitrogen by sodium hypochlorite accorded with a pseudo first-order kinetics model,and the influencing factors included Na Cl O dosage,initial concentration of ammonia nitrogen,salinity,temperature,and so on. When Na Cl O dosage was 0. 6%( MCl∶ MN= 13. 76),the reaction rate constant was up to 0. 015 75 min^(-1). The higher the initial concentration of ammonia nitrogen was,the worse the effect of oxidation reaction was. When the initial concentration did not exceed 45 mg/L,the effect on oxidation reaction rate constant increased with the increase of the initial concentration. Low salinity had no effect on ammonia nitrogen oxidation.When salinity was higher than 2. 0%,the inhibition effect on ammonia nitrogen oxidation would increase,and the reaction rate constant decreased obviously with the increase of salinity. The improvement of reaction temperature was beneficial to ammonia oxidation degradation. As temperature increased from 10 to 35 ℃,the reaction rate constant rose from 0. 00188 to 0. 01043 min^(-1).
文摘We developed a novel rapid hygrothermal pasteurization (RHP) method using saturated water vapor with a dew point of 100℃. The aim of this paper is to compare the effect of RHP treatment versus conventional sodium hypochlorite (NaClO) treatments on inactivation of natural mesophilic bacteria and quality attributes on fruits and vegetables. The RHP treatment was performed within a second by free-falling samples (cabbage, cucumber, carrot, bell pepper, pineapple and melon) through cylindrical processing chamber filled with steam. NaClO treatment was performed by washing samples with NaClO solution (100 mg/mL of free chlorine (pH 7), for 1 min). The RHP treatment showed a significantly higher inactivation effect than NaClO treatment on all tested samples. The RHP treatment had a slightly larger influence on color and vitamin C content than NaClO treatment in cabbage. Furthermore, the effects of treatment time and operated temperature were also determined using microbial model system. Elongation of treatment time did not significantly increase the microbial inactivation effect. Lowering of operated temperature by mixing air into steam tended to decrease the inactivation effect. From these results, RHP treatment could be used as an alternative method for decontaminating microorganisms on fruits and vegetables, except on leafy vegetable. In addition, it is suggested that microbial inactivation by RHP treatment was achieved through the initial condensation stage of water vapor on sample surface. By contrast, interfusion of air disturbed the effective condensation of water vapor.
基金the 11th Five-Year Plan of the National Scientific and Technological Program of China(No. 2007BAB22B01)the National Natural Science Foundation of China(No.50704036).
基金supported by the National Natural Science Foundation of China(No.81470771,No.81500887)the Natural Science Foundation of Hubei Province(No.2013CFA068)
文摘This study evaluated the effects of sodium hypochlorite(NaOCl) with different concentrations and exposure time on the structural, compositional and mechanical properties of human dentin in vitro. Sixty dentin slabs were obtained from freshly extracted premolars, randomly distributed into four groups(n=15), and treated with 1%, 5%, 10% NaOCl and distilled water(control group), respectively, for a total of 60 min. Attenuated total reflection infrared(ATR-IR) spectroscopy, Raman spectroscopy and X-ray diffraction(XRD) were carried out before, 10 min and 60 min after the treatment. Scanning electron microscopy(SEM) and flexural strength test were conducted as well. The results showed that dentins experienced morphological alterations in the NaOCl groups, but not in the control group. Two-way repeated-measures analysis of variance revealed that the carbonate:mineral ratio(C:M), Raman relative intensity(RRI), a-axis, c-axis length and full width at half maximum(FWHM) with the increase of time and concentration in the NaOCl groups were not significantly different from those in the control group(P〉0.05). Nevertheless, the mineral:matrix ratio(M:M) increased and the flexural strength declined with the increase of concentration and the extension of time in the NaOCl groups(P〈0.05). Additionally, it was found that the M:M and the flexural strength remained unchanged after 1% NaOCl treatment(P〉0.05), and the morphology changes were unnoticeable within 10 min in 1% NaOCl group. These results indicated that NaOCl has no significant effects on the inorganic mineral of human dentin; but it undermines and eliminates the organic content concentration-and time-dependently, which in turn influences the flexural strength and toughness of dentins. In addition, an irrigation of 1% NaOCl within 10 min can minimize the effects of NaOCl on the structural and mechanical properties of dentin during root canal treatment.
文摘Two modified electrodes (Pb/PbO2 and C/PbO2) were prepared by electrodepositing a lead oxide layer on lead and carbon sub- strates. These modified electrodes were used as anodes for the generation of sodium hypochlorite (NaOC1) from sodium chloride solution. Different operating conditions and factors affecting the treatment process of NaOC1 generation, including current density, pH values, con- ductive electrolytes, and electrolysis time, were studied and optimized. By comparison the C/PbO2 electrode shows a higher efficiency than the Pb/PbO2 electrode for the generation of NaOC1.
文摘Introduction: “RC-Prep”, a chemo-mechanical preparation for root canals, includes EDTA and urea peroxide as ingredients. For lubrication and its chelating effect, RC-Prep is useful as an adjunct in root canal enlargement. Furthermore, its cleaning action, due to its foaming properties in combi-nation with sodium hypochlorite, can be useful in root canal treatment in many situations. Methods: In a case of upper gingiva swelling, we used sodium hypochlorite with RC-Prep in the treatment of an infected root canal of the left maxillary premolar at the first visit. Within 2 min after use, the patient’s face became swollen. We kept the root canal open, and conducted a CT scan to investigate. Results: We diagnosed subcutaneous emphysema and prescribed 1 week of pain killers and antibiotics. The pain and swelling in the face finally resolved at 11 days after the incident. Conclusions: The cause of the emphysema was considered to have been the use of a sodium hypo-chlorite solution after using RC-Prep for an opened root apex.
文摘Sodium hypochlorite (NaOCl) or bleach, found in effluent from wastewater treatment plants, can act as an environmental toxin. The sea urchin Arbacia punctulata is a common subject of embryological toxicity tests due to its sensitivity to environmental pollutants. Using concentrations of NaOCl that mimic those found in treated wastewater (0.11 ppm, 0.06 ppm, and 0.03 ppm) we observed minimal affects on early larval development, though most larvae took longer to develop at higher NaOCl concentration. There was a significant difference in the percentage of non-normal plutei based on concentration (P = 0.038) and significant interaction between the percent of each morphology and NaOCl concentration (P = 0.0027). The most significant change in non-normal plutei was in the retarded (shortened skeletal rods) malformation which increased in frequency with NaOCl concentration (P = 0.001). There was a significant reduction in skeletal length in both normal and retarded plutei (P < 0.05) as NaOCl increased.
文摘5.1% of sodium hypochlorite (NaOCl) mixed with 2% of chlorhexidine (CHX) forms a brown precipitate that corresponds to para-chloroaniline (PCA), whether PCA is formed after the combination of NaOCl, CHX, and ethylenediaminetetraacetic acid (EDTA) by means of electron impact (high resolution and interlaced scanning) and ionization by fast atom bombardment (FAB), was analyzed. The brown precipitate, showed signals 127 and 153 Da, corresponding to p-chloroaniline and p-chlorophenyl isocyanate, respectively. These results were analyzed and compared with signals from the interlaced scanning program and confirmed with high resolution mass spectrometry analysis and compared with the NIST database. The mass spectra of this precipitated after different days confirmed the evolution of byproducts with the presence of a peak m/z = 127, due to the decrease of the fragment m/z = 153, which disappeared after 180 days. A blue and a white precipitate were observed by the addition of CHX (2%) with or without polyethylene glycol, respectively, EDTA (17%) and NaOCl (5.1%) precipitates contain chlorhexidine (m/z = 505), but no PCA was detected. We confirmed that PCA is not formed directly as a byproduct of CHX oxidation, but through the formation of the para-chlorophenyl isocyanate intermediate, which degrades slowly to PCA.
基金supported by grants from the National Natural Science Foundation of China(Grant Nos.:81673393 and 81874308)Taishan Scholar Program in Shandong Province,and Shandong Natural Science Foundation(Grant No.:ZR2018ZC0233).
文摘In recent years,various methods for detecting exogenous and endogenous hypochlorite have been studied,considering its essential role as a biomolecule.However,the existing technologies still pose obstacles such as their invasiveness,high costs,and complicated operation.In the current study,we developed a glow-type chemiluminescent probe,hypochlorite chemiluminescence probe(HCCL)-1,based on the scaffold of Schaap's 1,2-dioxetane luminophores.To better explore the physiological and pathological functions of hypochlorite,we modified the luminophore scaffold of HCCL-1 to develop several probes,including HCCL-2,HCCL-3,and HCCL-4,which amplify the response signal of hypochlorite.By comparing the luminescent intensities of the four probes using the IVIS®system,we determined that HCCL-2 with a limit of detection of 0.166 mM has enhanced sensitivity and selectivity for tracking hypochlorite both in vitro and in vivo.
文摘The majority of the refractory gold and silver occurs in occlusion in sulphides, then precious metal dissolution is possible by first oxidizing auriferous sulfide concentrate using sodium hypochlorite-sodium-hydroxide solution followed of pressure cyanidation of the oxidized concentrate, for the extraction of precious metals. This process was conducted and evaluated under cyanide and oxygen pressure. This versatile approach offers many advantages, including low temperatures, low pressure and less costly materials of construction than conventional pressure oxidation. In this study, the effect of oxygen pressure, concentration of sodium hypochlorite, temperature, and initial pH, in precious metals recovery and As removal were evaluated using a 24 factorial design. Characterization of the ores showed that pyrite and arsenopyrite were the main minerals present on the concentrate. The best results for gold extraction were obtained with oxygen pressure of 80 psi, 10% (w/w) sodium hypochlorite, temperature of 80℃, at pH = 13, and a constant stirring speed of 600 rpm. These conditions allowed an approximated 60% of gold and 90% of silver extractions in 1 hr.
基金Supported by the National Basic Research Program of China("973" Program,No.2011CB215302)National Natural Science Foundation of China(No.21206188 and 21106177)+1 种基金China Postdoctoral Science Foundation(No.2012M511339)Fundamental Research Funds for the Central Universities(No.2011QNA23)
文摘To investigate the structural features and provide an alternative method for high value-added utilization of coal, Lingwu coal was first extracted with organic solvent at room temperature. Then its extraction residue was oxidized in aqueous sodium hypochlorite(ASHC) under mild conditions. The effects of oxidation conditions, such as temperature, reaction time, the ratio of Lingwu coal extraction residue(LCER, g) to ASHC(m L) and p H value, on the product distributions and compositions were investigated. The results of gas chromatography/mass spectrometry(GC/MS) suggested that 53 kinds of methyl esterified products were detected in total, and benzene carboxylic acids were the main oxidation products, while chloro-substituted benzene carboxylic acids were the main by-products. Higher yield and fewer kinds of organic acids could be obtained at lower p H value, especially for the main objective product, benzene carboxylic acids.
基金supported by the America University,the Swiss Agency for Development and Cooperation,and the Central Technical Institute.
文摘Sodium hypochlorite has significant potential as a sanitation solution in hard-to-reach areas.Few studies have investigated the optimal electrolysis parameters for its production with volumes greater than 1o L.This study evaluated sodium hypochlorite production through electrolysis in a 22-L prototype and identified the optimal operating parameters.Tests were performed using graphite electrodes with areas of 68.4 cm²at the laboratory scale and 1865.0 cm?at the prototype scale.A design for experiments with different operating times,chloride concentrations,and electric current intensities was developed.The optimal operating time,sodium chloride concentration,and current intensity at the laboratory scale were 120 min,150 g of chloride per liter,and 3 A,respectively,leading to the production of 5.02 g/L of the disinfectant with an energy efficiency of 12.21 mg of Cl2 per kilojoule.At the prototype scale,the maximum sodium hypochlorite concentration of 3.99 g of chloride per liter was achieved with an operating time of 120 min,a sodium chloride concentration of 100 g of chloride per liter,and a current intensity of 70 A,reaching an energy efficiency of 42.56 mg of Cl2 per kilojoule.In addition,this study evaluated the influences of the chloride concentration,current intensity,and operating time on the production of sodium hypochlorite at the two scales,and formulated the equations showing the trends of sodium hypochlorite production and energy efficiency in the electrochemical systems.The 22-L prototype model for production of this oxidizing substance is promising for disinfection of large volumes of water in areas that are difficult to access.