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581.
582.
Guang Sun Gang Zhang Jingyong Liu Deniz Eren Evrendilek Musa Buyukada 《环境科学学报(英文版)》2021,33(9):124-137
An unavoidable but reusable waste so as to enhance a more circular waste utilization has been spent potlining (SPL) generated by the aluminum industry. The combustion mechanisms, evolved gasses, and ash properties of SPL were characterized dynamically in response to the elevated temperature and heating rates. Differential scanning calorimetric (DSC) results indicated an exothermic reaction behavior probably able to meet the energy needs of various industrial applications. The reaction mechanisms for the SPL combustion were best described using the 1.5-, 3- and 2.5-order reaction models. Fluoride volatilization rate of the flue gas was estimated at 2.24%. The SPL combustion emitted CO2, HNCO, NO, and NO2 but SOx. The joint optimization of remaining mass, derivative thermogravimetry, and derivative DSC was achieved with the optimal temperature and heating rate combination of 783.5°C, and 5 °C/min, respectively. Interaction between temperature and heating rate exerted the strongest and weakest impact on DSC and remaining mass, respectively. The fluorine mainly as the formation of substantial NaF and CaF2 in the residual ash. Besides, the composition and effect of environment of residual solid were evaluated. The ash slagging tendency and its mineral deposition mechanisms were elucidated in terms of turning SPL waste into a benign input to a circular waste utilization. 相似文献
583.
为解决贫燃条件下汽车尾气净化催化剂湿热稳定性差的问题,采用离子交换法把Ag离子交换到耐湿热性好的磷酸硅铝分子筛SAPO-34上,制备了有良好湿热稳定性的Ag-SAPO-34分子筛催化剂。研究结果表明:该催化剂经600℃、800℃高温水热处理8h后,活性分别平均降低2.3%和5.5%。水热处理初始4h时,催化剂活性下降2-5个百分点。随着水热处理时间增加到8-12h,催化剂活性的下降幅度逐渐减少至1-3个百分点,并趋向于稳定。同时,SEN、XRD表征测试结果表明,催化剂的表面形貌和骨架晶格结构在热处理和水热处理前后没有发生大的变化,这是催化剂耐湿热稳定性的根本原因。 相似文献
584.
镉与天然固体表面络合物的条件稳定常数 总被引:1,自引:1,他引:1
本文研究天然固体、伊利土和湘江悬浮沉积物从水中吸附极低浓度(ppb级)的镉时吸附量随pH的变化;同时研究不同pH值时的吸附等温线。根据简单的表面络合模式,利用线性关系及其分配系数,求取不同pH值时的天然固体与镉形成的表面络合物的条件稳定常数。条件稳定常数随pH值的上升,分为两个区域而呈线性增长。据此求得表面络合反应的条件络合常数。镉与伊利土和湘江悬浮沉积物的表面络合物条件稳定常数分别为3.0—1.8×10~2和0.8—2.5×10~2(pH5.0—8.5).低pH区伊利土和湘江悬浮沉积物吸附镉的条件络合常数分别为3.3×10~(-2)和2.8×10~(-2),高pH区二者的络合常数分别为5.6×10~(-5)和8.5×10~(-8)。 相似文献
585.
某隧道进口段滑坡的发生是由于隧道开挖过程中破碎围岩向隧道开挖临空面位移,进而引发的坡面岩土体的失稳。数值模拟结果表明,因隧道开挖引起的洞顶区边坡岩体应力水平下降的区域一直延续到地表,这种应力场的变化会直接导致边坡表面的变形和破坏,表现在以隧道轴线为中心,向两侧呈扇形展开的坡体产生了一定的沉降变形。对比结果表明滑坡区与由隧道开挖引起的坡体附加位移较大的区域基本相当,说明此滑坡是由于隧道开挖引起了围岩应力场调整,导致围岩产生向洞内的位移变形,从而使岩体发生松动而引发的。 相似文献
586.
587.
Samples of the moss Scleropodium purum collected in 1995 and 1997 were used to biomonitor the deposition of metals in the area surrounding a thermal power plant. Significantly higher levels of Cu (p<0.05), Fe (p<0.01), As and Hg (p<0.001) were found in the 1997 samples than in the 1995 samples, due to changes in atmospheric conditions. The influence on bioconcentration of the orientation of the sampling sites relative to the source of emission was studied. It was found that the increase recorded in 1997 generally occurred in the sampling sites in the south east of the study area. Analysis of the effect of distance from the source of emission revealed that the increase in metal levels in 1997 took place close to the power station (10–30 km). Finally, multiple regression analysis was used to construct a model that related different topographical variables to the concentrations of Hg in moss. The model, constructed using the data collected in both sampling periods, included the orientation of the sampling sites relative to the source of emission as well as the height of sampling sites in 1995 and the distance from the emission point in 1997. The model allowed us to determine the extent of the area affected by deposition and to establish the magnitude of deposition. 相似文献
588.
Samples of the moss Scleropodium purum collected in 1995 and 1997 were used to biomonitor the deposition of metals in the area surrounding a thermal power plant. Significantly higher levels of Cu (p<0.05), Fe (p<0.01), As and Hg (p<0.001) were found in the 1997 samples than in the 1995 samples, due to changes in atmospheric conditions. The influence on bioconcentration of the orientation of the sampling sites relative to the source of emission was studied. It was found that the increase recorded in 1997 generally occurred in the sampling sites in the south east of the study area. Analysis of the effect of distance from the source of emission revealed that the increase in metal levels in 1997 took place close to the power station (10–30 km). Finally, multiple regression analysis was used to construct a model that related different topographical variables to the concentrations of Hg in moss. The model, constructed using the data collected in both sampling periods, included the orientation of the sampling sites relative to the source of emission as well as the height of sampling sites in 1995 and the distance from the emission point in 1997. The model allowed us to determine the extent of the area affected by deposition and to establish the magnitude of deposition. 相似文献
589.
Pamela R. Veltkamp Kristen J. Hansen Robert M. Barkley Robert E. Sievers 《Environmental geochemistry and health》1996,18(2):77-80
Various organic compounds in aerosol particles in ambient air near a coniferous forest fire in Boulder, Colorado were identified as molecular markers of wood burning and forest fires. Particle samples were collected by filtering small volumes of air. The samples were analysed using thermal desorption followed by gas chromatographic separation and detection, a highly sensitive analytical method. Several compounds unique to softwood combustion were identified in the samples. Additionally, a predominance of odd-carbon-numbered n-alkanes over the corresponding even-carbon-numbered n-alkanes was observed. This predominance is a well-documented molecular pattern indicative of epicutical waxes in plants. 相似文献
590.
为了研究草本植物对排土场边坡加固能力,通过对排土场碱蓬和早熟禾根系生长情况进行调查,量化植物根随深度的分布关系,与此同时,采集2种草本植物根,通过根的抗拉试验,采用纤维束模型量化2种草本植物根黏聚力,采用FLAC3D分析边坡稳定性。结果表明,2种草本植物根的抗拉力与直径呈现幂律关系,根的抗拉力存在显著性差异。2种草本植物根面积比和根黏聚力均随深度的增加而降低,对比根黏聚力,碱蓬的根黏聚力大于早熟禾。草本植物加固后边坡安全系数提高,裸露边坡的安全系数为2.08,早熟禾与碱蓬加固的边坡的安全系数分别为2.09和2.1。 相似文献