Heavy metal pollution of soil has become one of the most common hazards in human development.The artificial freezing method,especially the progressive freezing method,can reduce heavy metal pollutants in the soil and ...Heavy metal pollution of soil has become one of the most common hazards in human development.The artificial freezing method,especially the progressive freezing method,can reduce heavy metal pollutants in the soil and promises to be an effective in-situ treatment of contaminated sites.This study analyzes the freezing purification mechanism of heavy metal contaminants in saturated sand and identifies three main factors that impact the effects of purification:freezing rate,initial concentration,and diffusion coefficient.Moreover,one-dimensional freezing tests are carried out by different freezing modes.The experimental results show that the heavy metal chromium could only be removed effectively with a slow freezing rate.By optimizing the freezing mode and freezing rate,a long section of soil was frozen and purified,with the maximum purification rate reaching 65.8%.This study shows that it is feasible to treat contaminated saturated sand by a gradual-cooling freezing method.展开更多
Electrochemical measurements of the solid-oxide galvanic cell, Mo|Mo+MoO2|ZrO2 (MgO)| Fe+ (FexO)+Ag| Fe, have been made at temperatures of 1473K and 1573K in order to obtain the activities of FexO in BaO-BaF2-FexO sla...Electrochemical measurements of the solid-oxide galvanic cell, Mo|Mo+MoO2|ZrO2 (MgO)| Fe+ (FexO)+Ag| Fe, have been made at temperatures of 1473K and 1573K in order to obtain the activities of FexO in BaO-BaF2-FexO slags used for dephosphorization of chromium-containing hot metal. The FexO activities show a significant dependence upon the molar ratio of BaO/BaF2. Within the homogeneous liquid region, the substitution of BaF2 for BaO has an effect of raising the FexO activity. From these activity data, the phase diagrams of the system BaO -BaF2-FexO are drawn at 1473K and 1573K. The temperature dependence of the activity coefficient of FexO at a fixed BaO/ BaF2 molar ratio can be expressed by formula RTlnγ(FexO)=constant.展开更多
Hexavalent chromium is one of the important heavy metals found in water and wastewater. The hexavalent form of chromium is considered to be a human carcinogen because of its mutagenic and carcinogenic properties. This...Hexavalent chromium is one of the important heavy metals found in water and wastewater. The hexavalent form of chromium is considered to be a human carcinogen because of its mutagenic and carcinogenic properties. This work has focused on the comparison of copper oxide nanoparticles and aluminium oxide nanoparticles for the removal of chromium(VI) from water. The cooper oxide nanoparticles (CuNP) and aluminium oxide nanoparticles (AlNP) were synthesised by sol gel method. Both the adsorbents were evaluated for the adsorption capacity using Langmuir and Freundlich adsorption model. The CuNP and AlNP were characterized for X-ray diffraction and SEM. The study indicated that the AlNP showed better removal as compared to CuNP and can be further explored as potential adsorbent for hexavalent chromium removal.展开更多
基金supported by Major State Basic Research Development Program(Grant No.2012CB026103)111 Project of China(Grant No.B14021)+1 种基金National Natural Science Foundation of China(Grant No.51104146,Grant No.41271096)Open Fund of State Key Laboratory of Frozen Soil Engineering(Grant No.SKLFSE201704)。
文摘Heavy metal pollution of soil has become one of the most common hazards in human development.The artificial freezing method,especially the progressive freezing method,can reduce heavy metal pollutants in the soil and promises to be an effective in-situ treatment of contaminated sites.This study analyzes the freezing purification mechanism of heavy metal contaminants in saturated sand and identifies three main factors that impact the effects of purification:freezing rate,initial concentration,and diffusion coefficient.Moreover,one-dimensional freezing tests are carried out by different freezing modes.The experimental results show that the heavy metal chromium could only be removed effectively with a slow freezing rate.By optimizing the freezing mode and freezing rate,a long section of soil was frozen and purified,with the maximum purification rate reaching 65.8%.This study shows that it is feasible to treat contaminated saturated sand by a gradual-cooling freezing method.
文摘Electrochemical measurements of the solid-oxide galvanic cell, Mo|Mo+MoO2|ZrO2 (MgO)| Fe+ (FexO)+Ag| Fe, have been made at temperatures of 1473K and 1573K in order to obtain the activities of FexO in BaO-BaF2-FexO slags used for dephosphorization of chromium-containing hot metal. The FexO activities show a significant dependence upon the molar ratio of BaO/BaF2. Within the homogeneous liquid region, the substitution of BaF2 for BaO has an effect of raising the FexO activity. From these activity data, the phase diagrams of the system BaO -BaF2-FexO are drawn at 1473K and 1573K. The temperature dependence of the activity coefficient of FexO at a fixed BaO/ BaF2 molar ratio can be expressed by formula RTlnγ(FexO)=constant.
文摘Hexavalent chromium is one of the important heavy metals found in water and wastewater. The hexavalent form of chromium is considered to be a human carcinogen because of its mutagenic and carcinogenic properties. This work has focused on the comparison of copper oxide nanoparticles and aluminium oxide nanoparticles for the removal of chromium(VI) from water. The cooper oxide nanoparticles (CuNP) and aluminium oxide nanoparticles (AlNP) were synthesised by sol gel method. Both the adsorbents were evaluated for the adsorption capacity using Langmuir and Freundlich adsorption model. The CuNP and AlNP were characterized for X-ray diffraction and SEM. The study indicated that the AlNP showed better removal as compared to CuNP and can be further explored as potential adsorbent for hexavalent chromium removal.
