Red-mud is the residue from the Bayer process, in which the iron minerals should be removed before red-mud is used to produce refractory materials. The iron minerals in red-mud were extracted by oxalic acid solution. ...Red-mud is the residue from the Bayer process, in which the iron minerals should be removed before red-mud is used to produce refractory materials. The iron minerals in red-mud were extracted by oxalic acid solution. The content of Fe （calculated in Fe203） in red-mud was reduced from 17.6% to less than 1% after being treated by 1 mol/L oxalic acid solution at 75 ℃ for 2 h. The Fe（Ⅲ） oxalate solution obtained was then irradiated by UV light, resulting in the precipitation of Fe（Ⅱ） oxalate. Under UV photocatalysis, more than 90% of Fe（Ⅲ） oxalate in the extracted solution was transformed into the precipitation of Fe（Ⅱ） oxalate crystallite （fl-FeC2O4·2H2O）. The filtrate from the Fe（Ⅱ） oxalate precipitate filtration could be reused in the next cycle. The mechanism ofUV photocatalysis precipitation was also discussed.展开更多
Bauxite residue is a highly alkaline waste product from refining bauxite ore.Bioremediation driven by microbial activities has been evidently effective in lowering the alkalinity of bauxite residues,which is critical ...Bauxite residue is a highly alkaline waste product from refining bauxite ore.Bioremediation driven by microbial activities has been evidently effective in lowering the alkalinity of bauxite residues,which is critical to the initiation of pedogenesis under engineered conditions.The present study investigated the changes of alkalinity and aggregation of bauxite residue at different depth in response to the colonization of Penicillium oxalicum in columns.The results demonstrated that the inoculation of P.oxalicum decreased the residue’s pH to about 7 after 30 d only at the surface layer,which was exposed to aerobic conditions.The formation of aggregates was improved overall in the organic matter treated bauxite residue.However,the EC of bauxite residue increased with time under the incubation condition,probably due to accelerated hydrolysis of sodium-rich minerals.The inoculation of P.oxalicum had no effects on urease activity,but increased cellulose enzyme activity at surface layer only.展开更多
This paper presents the data from two-year experiments concerning with doses of sewage sludge （0, 7, 14 and 21 ton.ha^-1） and inorganic nitrogen doses （0, 50, 100 and 150 kg.ha^-1） from the Municipality of Van, wh...This paper presents the data from two-year experiments concerning with doses of sewage sludge （0, 7, 14 and 21 ton.ha^-1） and inorganic nitrogen doses （0, 50, 100 and 150 kg.ha^-1） from the Municipality of Van, which is located at an altitude of 1,725 m of eastern Anatolia in Turkey. A study was conducted to assess two different N sources on sandy-silty-clay soils grown to crested wheatgrass Agropyron cristatum （L.） Gaertn, grass pasture which had been amended with sewage sludge for two years. Plant tissue and DTPA （diethylenetriamine pentaacetic acid） extractable soil nutrient were evaluated; twelve elements were analyzed in the plant tissue and six elements in the soil extract in different soil depths. The research demonstrated that the applications produced increase contents of N, P, Mg, Mn, Zn and Pb in the plant. There was a significant （P 〈 0.01） accumulation of DTPA extractable concentrations of Fe, Mn, Cu, Zn and Pb in the top soil horizon. Also, sewage sludge resulted in 51 folded increase in extractable P in 0-20 cm soil horizon. However, DTPA concentrations of in soil showed that Fe exhibited a significant positive correlation with the concentrations of exchangeable fractions of Mn, Cu, Zn and Pb with the correlation. Positive correlations were also observed between Cu-Mn, Mn-Zn, Mn-Pb, Cu-Zn, Cu-Pb and Zn-Pb concentrations. In the same way, plant uptake of the Mn, Zn and Pb was highly correlated with concentrations of Cu, Zn and Pb in the soil. It was concluded that sewage sludge is a valuable source of nutrient and also provides an opportunity to increase soil organic matter.展开更多
One of the biggest problems responsible of the nonrenewable resources depletion and environmental issues is the construction industries,which generates large amounts of mineral waste and harmful emitted gases.Therefor...One of the biggest problems responsible of the nonrenewable resources depletion and environmental issues is the construction industries,which generates large amounts of mineral waste and harmful emitted gases.Therefore,these problems generated the necessity to search for alternative natural building materials based on renewable resources.To study the mechanical characteristics and microstructural behavior of the concrete reinforced by raw wheat straw basalt fiber composite(RWSBFc),and treated rice straw basalt fiber composite(TRSBFc),a number of experimental tests were carried out with different composites ratios.Concrete compressive strength,splitting tensile strength,and flexural strength tests were considered as main parameters.The results showed that the RWSBFC has a positive effect on concrete flexural strength by increasing of 12.58%,compared with control samples.Also,it showed good enhancement in concrete flexibility and ductility.In contrast,both RWSBFc and TRSBFc showed uneven deterioration in concrete compressive strength and splitting tensile strength.To avoid the deterioration in compressive strengths of the various composites types,some improvement methods such as processors for the used straw,and adding some additives were recommended.展开更多
基金Project (2010AA101703) supported by the National Hi-tech Research and Development Program of China
文摘Red-mud is the residue from the Bayer process, in which the iron minerals should be removed before red-mud is used to produce refractory materials. The iron minerals in red-mud were extracted by oxalic acid solution. The content of Fe （calculated in Fe203） in red-mud was reduced from 17.6% to less than 1% after being treated by 1 mol/L oxalic acid solution at 75 ℃ for 2 h. The Fe（Ⅲ） oxalate solution obtained was then irradiated by UV light, resulting in the precipitation of Fe（Ⅱ） oxalate. Under UV photocatalysis, more than 90% of Fe（Ⅲ） oxalate in the extracted solution was transformed into the precipitation of Fe（Ⅱ） oxalate crystallite （fl-FeC2O4·2H2O）. The filtrate from the Fe（Ⅱ） oxalate precipitate filtration could be reused in the next cycle. The mechanism ofUV photocatalysis precipitation was also discussed.
基金Projects(41877511,41842020)supported by the National Natural Science Foundation of ChinaProject(2018zzts421)supported by the Innovative Project of Independent Exploration of Central South University,China
文摘Bauxite residue is a highly alkaline waste product from refining bauxite ore.Bioremediation driven by microbial activities has been evidently effective in lowering the alkalinity of bauxite residues,which is critical to the initiation of pedogenesis under engineered conditions.The present study investigated the changes of alkalinity and aggregation of bauxite residue at different depth in response to the colonization of Penicillium oxalicum in columns.The results demonstrated that the inoculation of P.oxalicum decreased the residue’s pH to about 7 after 30 d only at the surface layer,which was exposed to aerobic conditions.The formation of aggregates was improved overall in the organic matter treated bauxite residue.However,the EC of bauxite residue increased with time under the incubation condition,probably due to accelerated hydrolysis of sodium-rich minerals.The inoculation of P.oxalicum had no effects on urease activity,but increased cellulose enzyme activity at surface layer only.
文摘This paper presents the data from two-year experiments concerning with doses of sewage sludge （0, 7, 14 and 21 ton.ha^-1） and inorganic nitrogen doses （0, 50, 100 and 150 kg.ha^-1） from the Municipality of Van, which is located at an altitude of 1,725 m of eastern Anatolia in Turkey. A study was conducted to assess two different N sources on sandy-silty-clay soils grown to crested wheatgrass Agropyron cristatum （L.） Gaertn, grass pasture which had been amended with sewage sludge for two years. Plant tissue and DTPA （diethylenetriamine pentaacetic acid） extractable soil nutrient were evaluated; twelve elements were analyzed in the plant tissue and six elements in the soil extract in different soil depths. The research demonstrated that the applications produced increase contents of N, P, Mg, Mn, Zn and Pb in the plant. There was a significant （P 〈 0.01） accumulation of DTPA extractable concentrations of Fe, Mn, Cu, Zn and Pb in the top soil horizon. Also, sewage sludge resulted in 51 folded increase in extractable P in 0-20 cm soil horizon. However, DTPA concentrations of in soil showed that Fe exhibited a significant positive correlation with the concentrations of exchangeable fractions of Mn, Cu, Zn and Pb with the correlation. Positive correlations were also observed between Cu-Mn, Mn-Zn, Mn-Pb, Cu-Zn, Cu-Pb and Zn-Pb concentrations. In the same way, plant uptake of the Mn, Zn and Pb was highly correlated with concentrations of Cu, Zn and Pb in the soil. It was concluded that sewage sludge is a valuable source of nutrient and also provides an opportunity to increase soil organic matter.
基金supported in part by the Priority Academic Program Development of Jiangsu Higher Education Institutions under Grant 1105007002.
文摘One of the biggest problems responsible of the nonrenewable resources depletion and environmental issues is the construction industries,which generates large amounts of mineral waste and harmful emitted gases.Therefore,these problems generated the necessity to search for alternative natural building materials based on renewable resources.To study the mechanical characteristics and microstructural behavior of the concrete reinforced by raw wheat straw basalt fiber composite(RWSBFc),and treated rice straw basalt fiber composite(TRSBFc),a number of experimental tests were carried out with different composites ratios.Concrete compressive strength,splitting tensile strength,and flexural strength tests were considered as main parameters.The results showed that the RWSBFC has a positive effect on concrete flexural strength by increasing of 12.58%,compared with control samples.Also,it showed good enhancement in concrete flexibility and ductility.In contrast,both RWSBFc and TRSBFc showed uneven deterioration in concrete compressive strength and splitting tensile strength.To avoid the deterioration in compressive strengths of the various composites types,some improvement methods such as processors for the used straw,and adding some additives were recommended.
