Lime mud is a kind of solid waste in the papermaking industry,which has been a source of serious environmental pollution.Ceramsites containing anorthite and gehlenite were prepared from lime mud and fly ash through th...Lime mud is a kind of solid waste in the papermaking industry,which has been a source of serious environmental pollution.Ceramsites containing anorthite and gehlenite were prepared from lime mud and fly ash through the solid state reaction method at 1050°C.The objective of this study was to explore the efficiency of Ca^2＋ and OH-release and assess the phosphorus and copper ion removal performance of the ceramsites via batch experiments,X-ray diffraction（XRD） and scanning electron microscopy（SEM）.The results show that Ca^2＋ and OH-were released from the ceramsites due to the dissolution of anorthite,gehlenite and available lime.It is also concluded that gehlenite had stronger capacity for Ca^2＋ and OH-release compared with anorthite.The Ca^2＋ release could be fit well by the Avrami kinetic model.Increases of porosity,dosage and temperature were associated with increases in the concentrations of Ca^2＋ and OH-released.Under different conditions,the ceramsites could maintain aqueous solutions in alkaline conditions（p H = 9.3–10.9） and the release of Ca^2＋ was not affected.The removal rates of phosphorus and copper ions were as high as 96.88% and 96.81%,respectively.The final p H values of both phosphorus and copper ions solutions changed slightly.The reuse of lime mud in the form of ceramsites is an effective strategy.展开更多
Lime mud （LM）, a solid waste from the paper mill, is used as an economic and environmental friendly heterogeneous basic catalyst for transesterification, which is accompanied by characterization of X-ray fluorescenc...Lime mud （LM）, a solid waste from the paper mill, is used as an economic and environmental friendly heterogeneous basic catalyst for transesterification, which is accompanied by characterization of X-ray fluorescence, thermogravimetric-differential thermal analysis, X-ray diffraction, N2 adsorption, and Hammett indicator method. To investigate the performance of the achieved catalyst, which is activated through calcination, the aspects of calcination temperature, reaction time, mole ratio of methanol to oil, catalyst addition percentage, and reaction temperature are concerned. Characterization of catalyst reveals that LM could be activated through calcination to transform the carbonate and hydrate of calcium into the oxide forms and higher calcination temperature could lead to stronger basic strength. However, N2 adsorption results indicate that higher temperature causes the sintering of the catalyst and shrinkage of the catalyst grains. When LM is activated at 800℃ （LM-800） and the reac- tion is carried out at 64℃ with a methanol to oiL mole ratio of 15：1, catalyst addition percentage of 6%, and reaction time of 2 h, the maximum transesterification conversion of 94.35% could be achieved. Reusability of LM-800 is also investigated com- pared with laboratory grade CaO in five reaction cycles and the results indicate that the catalysts derived from LM can be used as an economic and efficient catalyst for biodiesel production.展开更多
Three identical model boxes were made from transparent plexiglass and angle iron. Using the method of sinking water and according to the sedimentary rhythm of saturated calcium carbonate （lime-mud） intercalated with...Three identical model boxes were made from transparent plexiglass and angle iron. Using the method of sinking water and according to the sedimentary rhythm of saturated calcium carbonate （lime-mud） intercalated with cohesive soil, calcites with particle sizes diameters of ≤ 5 μm, 10–15 μm and 23–30 μm as well as cohesive soil were sunk alternatively in water of three boxes to build three test models, each of which has a specific size of calcite. Pore water pressure gauges were buried in lime-mud layers at different depths in each model, and connected with a computer system to collect pore water pressures. By means of soil tests, physical property parameters and plasticity indices （Ip） were obtained for various grain-sized saturated lime-muds. The lime-muds with Ip ranging from 6.3 to 8.5 （lower than 10） are similar to liquid saturated silt in the physical nature, indicating that saturated silt can be liquefied once induced by a strong earthquake. One model cart was pushed quickly along the length direction of the model so that its rigid wheels collided violently with the stone stair, thus generating an artificial earthquake with seismic wave magnitude greater than VI degree. When unidirectional cyclic seismic load of horizontal compression-tension-shear was imposed on the soil layers in the model, enough great pore water pressure has been accumulated within pores of lime-mud, resulting in liquefaction of lime-mud layers. Meanwhile, micro-fractures formed in each soil layer provided channels for liquefaction dewatering, resulting in formation of macroscopic liquefaction deformation, such as liquefied lime-mud volcanoes, liquefied diapir structures, vein-like liquefied structures and liquefied curls, etc. Splendid liquefied lime-mud eruption lasted for two to three hours, which is similar to the sand volcano eruption induced by strong earthquake. However, under the same artificial seismic conditions, development of macroscopic liquefied structures in three experimental models varied in shape, depth and quantity, indicating that excess pore water pressure ratios at initial liquefaction stage and complete liquefaction varied with depth. With size increasing of calcite particle in lime-mud, liquefied depth and deformation extent increase accordingly. The simulation test verifies for the first time that strong earthquakes may cause violent liquefaction of saturated lime-mud composed of micron-size calcite particles, uncovering the puzzled issue whether seafloor lime-mud can be liquefied under strong earthquake. This study not only provides the latest simulation data for explaining the earthquake-induced liquefied deformations of saturated lime-mud and seismic sedimentary events, but also is of great significance for analysis of foundation stability in marine engineering built on the soft calcium carbonate layers in neritic environment.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos.51578289 and 51468053)the Technology Major Projects of China (No.2012ZX04010-032)+1 种基金the Research and innovation program of graduate students in Jiangsu Province (No.KYLX_0347)the Innovation Fund for National Small and Medium Technology Based Firms of China (No.11C26213201410)
文摘Lime mud is a kind of solid waste in the papermaking industry,which has been a source of serious environmental pollution.Ceramsites containing anorthite and gehlenite were prepared from lime mud and fly ash through the solid state reaction method at 1050°C.The objective of this study was to explore the efficiency of Ca^2＋ and OH-release and assess the phosphorus and copper ion removal performance of the ceramsites via batch experiments,X-ray diffraction（XRD） and scanning electron microscopy（SEM）.The results show that Ca^2＋ and OH-were released from the ceramsites due to the dissolution of anorthite,gehlenite and available lime.It is also concluded that gehlenite had stronger capacity for Ca^2＋ and OH-release compared with anorthite.The Ca^2＋ release could be fit well by the Avrami kinetic model.Increases of porosity,dosage and temperature were associated with increases in the concentrations of Ca^2＋ and OH-released.Under different conditions,the ceramsites could maintain aqueous solutions in alkaline conditions（p H = 9.3–10.9） and the release of Ca^2＋ was not affected.The removal rates of phosphorus and copper ions were as high as 96.88% and 96.81%,respectively.The final p H values of both phosphorus and copper ions solutions changed slightly.The reuse of lime mud in the form of ceramsites is an effective strategy.
基金supported by the National Natural Science Foundation of China(Grant No.51206098)the Promotive Research Fund for Excellent Young and Middle-aged Scientists of the Shandong Province,China(Grant No.BS2012NJ005)Independent Innovation Foundation of Shandong University(IIFSDU,2011GN048)
文摘Lime mud （LM）, a solid waste from the paper mill, is used as an economic and environmental friendly heterogeneous basic catalyst for transesterification, which is accompanied by characterization of X-ray fluorescence, thermogravimetric-differential thermal analysis, X-ray diffraction, N2 adsorption, and Hammett indicator method. To investigate the performance of the achieved catalyst, which is activated through calcination, the aspects of calcination temperature, reaction time, mole ratio of methanol to oil, catalyst addition percentage, and reaction temperature are concerned. Characterization of catalyst reveals that LM could be activated through calcination to transform the carbonate and hydrate of calcium into the oxide forms and higher calcination temperature could lead to stronger basic strength. However, N2 adsorption results indicate that higher temperature causes the sintering of the catalyst and shrinkage of the catalyst grains. When LM is activated at 800℃ （LM-800） and the reac- tion is carried out at 64℃ with a methanol to oiL mole ratio of 15：1, catalyst addition percentage of 6%, and reaction time of 2 h, the maximum transesterification conversion of 94.35% could be achieved. Reusability of LM-800 is also investigated com- pared with laboratory grade CaO in five reaction cycles and the results indicate that the catalysts derived from LM can be used as an economic and efficient catalyst for biodiesel production.
基金supported by the National Natural Science Foundation of China(NSFC-41272066)the Program for Changjiang Scholars & Innovative Research Team of the University of China(IRT-13075)
文摘Three identical model boxes were made from transparent plexiglass and angle iron. Using the method of sinking water and according to the sedimentary rhythm of saturated calcium carbonate （lime-mud） intercalated with cohesive soil, calcites with particle sizes diameters of ≤ 5 μm, 10–15 μm and 23–30 μm as well as cohesive soil were sunk alternatively in water of three boxes to build three test models, each of which has a specific size of calcite. Pore water pressure gauges were buried in lime-mud layers at different depths in each model, and connected with a computer system to collect pore water pressures. By means of soil tests, physical property parameters and plasticity indices （Ip） were obtained for various grain-sized saturated lime-muds. The lime-muds with Ip ranging from 6.3 to 8.5 （lower than 10） are similar to liquid saturated silt in the physical nature, indicating that saturated silt can be liquefied once induced by a strong earthquake. One model cart was pushed quickly along the length direction of the model so that its rigid wheels collided violently with the stone stair, thus generating an artificial earthquake with seismic wave magnitude greater than VI degree. When unidirectional cyclic seismic load of horizontal compression-tension-shear was imposed on the soil layers in the model, enough great pore water pressure has been accumulated within pores of lime-mud, resulting in liquefaction of lime-mud layers. Meanwhile, micro-fractures formed in each soil layer provided channels for liquefaction dewatering, resulting in formation of macroscopic liquefaction deformation, such as liquefied lime-mud volcanoes, liquefied diapir structures, vein-like liquefied structures and liquefied curls, etc. Splendid liquefied lime-mud eruption lasted for two to three hours, which is similar to the sand volcano eruption induced by strong earthquake. However, under the same artificial seismic conditions, development of macroscopic liquefied structures in three experimental models varied in shape, depth and quantity, indicating that excess pore water pressure ratios at initial liquefaction stage and complete liquefaction varied with depth. With size increasing of calcite particle in lime-mud, liquefied depth and deformation extent increase accordingly. The simulation test verifies for the first time that strong earthquakes may cause violent liquefaction of saturated lime-mud composed of micron-size calcite particles, uncovering the puzzled issue whether seafloor lime-mud can be liquefied under strong earthquake. This study not only provides the latest simulation data for explaining the earthquake-induced liquefied deformations of saturated lime-mud and seismic sedimentary events, but also is of great significance for analysis of foundation stability in marine engineering built on the soft calcium carbonate layers in neritic environment.
