Lake sediment treatment with aluminum, iron, calcium and nitrate additives to reduce phosphorus release

Treatment of lake sediments with salts is a promising approach for preventing phosphorus release from sediments. Five 35-d treatments of undisturbed sediment cores in the East Lake, Wuhan, China were applied under anoxic conditions： nothing added （control）, Al2（SO4）3 added, FeCl3 added, CaCl2 added, and NaNO3 added. To identify changes in the P binding sites in the sediment caused by the treatments, different P binding forms were extracted from the sediment before and after the treatments. We found that the mean P release rates for anoxic treatments with Al2（SO4）3, FeCl3, CaCl2 and NaNO3 were -0.6, 0.03, 0.6 and 2.6 mg/（m^2·d）, respectively, while the P release rate with no additives was 7.3 mg/（m^2·d）. In suboxic conditions, the concentration of total phosphorus （TP ge 657 mg/kg） in sediment was much lower than that of untreated sediment （TPaverage 688 mg/kg） and treatments with salts （TP（Al2（SO4）3） 793 mg/kg, TP（FeCl3） 781 mg/kg, TP（NaNO3） 802 mg/kg, TP（CaCl2） 747 mg/kg）. We also found that adding CaCl2 prevented P release because of apatite formation and because PCa （Ca bound P） increased at the sediment surface. Addition of Fe^3＋ and NO3^- to the sediment increased the amounts of PFe. Mn （Redox-sensitive P, mostly Fe and Mn compounds）, since iron oxide has the ability to combine P. Addition of Al2（SO4）3 increased the fraction of PAl, Fe （P bound to metal oxides （Al, Fe）） and decreased the P and Fe in the water above the anoxic sediment, showing the greater ability orAl in binding P. The results showed that Al2（SO4）3, FeCl3, CaCl2 and NaNO3 all had an effect in controlling phosphorus release. The effect was related to the forms of phosphorus existing in the sediment before treatment and the forms resulting after adding the four reagents. The combination of Al^3＋ or Fe^3＋ with NO3^- promises to be a reasonable chemical treatment for increasing the P retention capacity of sediments in eutrophic lakes. If chemical treatment is combined with bioremediation, the aim of environmental repair may be achieved.     

Low temperature sintering and performance of aluminum nitride/borosilicate glass

Aluminum nitride （AlN）/borosilicate glass composites were prepared by the tape casting process and hot-press sintered at 950 ℃ with AIN and SiO2-B203-ZnO-Al2O3-Li2O glass as starting materials. We characterized and analyzed the variation of the microstructure, bulk density, porosity, dielectric constant, thermal conductivity and thermal expansion coefficient （TEC） of the ceramic samples as a function of AIN content. Results show that AIN and SiO2-B2O3-ZnO-Al2O3-Li2O glass can be sintered at 950 ℃, and ZnAI204 and Zn2SiO4 phase precipitated to form glass-ceramic. The performance of the ceramic samples was determined by the composition and bulk density of the composites. Lower AlN content was found redounding to liquid phase sintering, and higher bulk density of composites can be accordingly obtained. With the increase of porosity, corresponding decreases were located in the dielectric constant, thermal conductivity and TEC of the ceramic samples. When the mass fraction of AlN was 40%, the ceramic samples possessed a low dielectric constant （4.5-5.0）, high thermal conductivity （11.6 W/（m.K）） and a proper TEC （3.0× 10^-6 K^-1 which matched that of silicon）. The excellent performance makes this kind of low temperature co-fired ceramic a promising candidate for application in the micro-electronics packaging industry.     

Utilization of fly ash from coal-fired power plants in China

The rapidly increasing demand for energy in China leads to the construction of new power plants all over the country. Coal, as the main fuel resource of those power plants, results in increasing problems with the disposal of solid residues from combustion and off gas cleaning. This investigation describes chances for the utilization of fly ash from coal-fired power plants in China. After briefly comparing the situation in China and Germany, the status of aluminum recycling from fly ash and the ad- vantages for using fly ash in concrete products are introduced. Chemical and physical analyses of Chinese fly ash samples, e.g., X-ray diffraction （XRD）, ICP （Inductive Coupled Plasma） and particle size analysis, water requirement, etc. are presented. Rea- sonable amounts of aluminum were detected in the samples under investigation, but for recovery only sophisticated procedures are available up to now. Therefore, simpler techniques are suggested for the first steps in the utilization of Chinese fly ash.     

新荧光试剂1—(4—羟基水杨醛缩氨基)—8—羟基—3,6—萘二磺酸钠荧光熄灭法测定痕量铝

本文采用荧光熄灭法在水相中研究了席夫碱试剂l—(4—羟基水杨醛缩氨基)—8—羟基—3,6—萘二磺酸钠(HSHND)测定痕量Al(Ⅲ)的方法和条件。在PH=4.2的邻苯二甲酸氢钾缓冲体系中,试剂的激发波长λ_(ex)=356nm,荧炮发射波长λ_(em)=418nm,铝(Ⅲ)浓度在0.5—3.0μg/10mL范围内呈良好的线性关系,检出限为0.2μg/10mL。本法的灵敏度及选择性好,操作简便快速,无需加热。用于水样中痕量铝的测定,结果满意。     

铸铝件油漆开裂脱落的原因分析

针对某产品在高低温贮存过程中天线座转台（铸铝件）出现油漆从腻子层开裂、脱落现象,通过对比不同工艺方法制作的样件,在温度储存、温度循环试验情况下是否满足要求,从而查找出天线座转台（铸铝件）油漆从腻子层开裂、脱落的原因。     

浅谈提高铝熔体质量的措施

文章指出铝熔体中气体和夹杂物的主要来源,介绍常用的铝熔体净化技术,提出加强原辅材料管理,注重熔炼操作细节,选择合适的炉型和净化工艺等,是提高铝熔体质量的有效措施。     

如何保证铝合金零件阳极氧化着色一致性

针对某铝合金零件经阳极氧化着色存在颜色差异大,一次性合格率低,设计出新型阳极氧化挂具,并对抛光液采用压缩空气搅拌,从而提高产品一次性合格率。     

二次酸浸法提取煤灰中的氧化铝(英文)

目的:煤灰渣酸浸提铝通常效率不高,主要因为灰渣中存在含铝晶体矿物(如莫来石、尖晶石和长石等)。为解决含铝晶体不易与硫酸反应的问题,本文提出二次酸浸提铝法。创新点:基本实现铝硅分离,第一步酸浸实现非晶态铝的浸出,残渣经焙烧和水浸后,第二步酸浸实现剩余铝的浸出。方法:1.一次酸浸时,硫酸直接与煤灰渣反应浸出部分氧化铝,提铝残渣加碳酸钠焙烧后,含铝晶体遭到破坏;2.焙烧产物经水浸溶解出硅酸钠,水浸残渣做X射线衍射分析表明其主要为铝硅非晶体活性物质,此时可用硫酸在温和条件下浸出剩余的铝。结论:1.一次酸浸提铝在10 mol/L硫酸、120°C、2 h和1:2固液比的条件下,铝浸出率为81.72%;2.用5 mol/L硫酸二次酸浸时,20°C下铝浸出率已经达到87.31%,100°C下更是达到99.06%;3.综合两次酸浸结果,铝的浸出总效率在97%以上。     

铝合金压铸件表面处理方法讨论

铝合金是以铝为基的合金总称,在航空航天、机械制造、工业生产方面都是应用最广泛的有色金属结构材料。随着科学技术以及工业经济的迅猛发展,人们越来越关注铝合金的生产方式以及表面处理的方法。众所周知,铝合金在潮湿的空气中易腐蚀,这种腐蚀不仅使铝合金的表面变得粗糙而且也对铝合金的性能造成了一定的影响。详细地介绍了一些对铝合金压铸件表面的物理处理方法以及化学处理方法,有效防止了铝合金的腐蚀,为提高工业生产的效率带来了好处。     

Interaction of catechins with aluminum in vitro

INTRODUCTION nd that catechin-metal complexes had strong bio- activities (Midori et al., 2001). But, it is not clear Because of the aluminum accumulation in tea what the mechanism of combination of catechinsplant, the safety hazard of aluminum absorption with aluminum ion is (Inoue et al., 2002), and alsowhile drin…