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31.
In this research, the efficiency of electrocoagulation treatment process using aluminum electrodes to treat synthetic wastewater containing Reactive Red198 (RR198) was studied. The effects of parameters such as voltage, time of reaction, electrode connection mode, initial dye concentration, electrolyte concentration, and inter electrode distance on dye removal efficiency were investigated. In addition, electrical energy consumption, electrode consumption, and operating cost at optimum condition have been investigated. The results showed that dye and chemical oxygen demand removals were 98.6 and 84%, respectively. Electrode consumption, energy consumption and operating cost were 0.052 kg/m3, 1.303 kWh/m3 and 0.256 US$/m3, respectively. Dye removal kinetic followed first order kinetics. It can be concluded that electrocoagulation process by aluminum electrode is very efficient and clean process for reactive dye removal from colored wastewater. 相似文献
32.
Laura Schaefer 《Icarus》2004,169(1):216-241
We modified the MAGMA chemical equilibrium code developed by Fegley and Cameron (1987, Earth Planet. Sci. Lett. 82, 207-222) and used it to model vaporization of high temperature silicate lavas on Io. The MAGMA code computes chemical equilibria in a melt, between melt and its equilibrium vapor, and in the gas phase. The good agreement of MAGMA code results with experimental data and with other computer codes is demonstrated. The temperature-dependent pressure and composition of vapor in equilibrium with lava is calculated from 1700 to 2400 K for 109 different silicate lavas in the ONaKFeSiMgCaAlTi system. Results for five lavas (tholeiitic basalt, alkali basalt, Barberton komatiite, dunite, and a molten type B1 Ca, Al-rich inclusion) are discussed in detail. The effects of continuous fractional vaporization on chemistry of these lavas and their equilibrium vapor are presented. The predicted abundances (relative to Na) of K, Fe, Si, Al, Ca, and Ti in the vapor equilibrated with lavas at 1900 K are lower than published upper limits for Io's atmosphere (which do not include Mg). We predict evaporative loss of alkalis, Fe, and Si during volcanic eruptions. Sodium is more volatile than K, and the Na/K ratio in the gas is decreased by fractional vaporization. This process can match Io's atmospheric Na/K ratio of 10±3 reported by Brown (2001, Icarus 151, 190-195). Silicon monoxide is an abundant species in the vapor above lavas. Spectroscopic searches are recommended for SiO at IR and mm wavelengths. Reactions of metallic vapors with S- and Cl-bearing volcanic gases may form other unusual gases including MgCl2, MgS, MgCl, FeCl2, FeS, FeCl, and SiS. 相似文献
33.
As technical advances have dramatically increased our ability to analyze trace elements, the need for more reliable data on
the compositional dependence of trace element partitioning between minerals and melt has become increasingly important. The
late-Cretaceous Carmacks Group of south central Yukon comprises a succession of primitive high-Mg ankaramitic lavas characterized
by shoshonitic chemical affinities and containing large complexly zoned clinopyroxene phenocrysts. The compositional zonation
of the clinopyroxene phenocrysts is characterized by relatively Fe-rich (Mg# = Mg/(Mg + Fe) = 0.85), but mottled, cores surrounded by mantles of cyclically-zoned clinopyroxene whose Mg# varies repeatedly between 0.9 and 0.80. These cyclically zoned clinopyroxene mantles appear to record the repeated influx
and mixing of batches of primitive with more evolved magma in a deep sub-crustal (∼1.2 GPa) magma chamber(s). Laser ablation
ICP-MS was used to analyze the trace element variation in these zoned clinopyroxenes. The results indicate more than a threefold
variation in the absolute concentrations of Th, Zr, rare earth elements (REE), and Y within individual clinopyroxene phenocrysts,
with no apparent change in the degree of REE or high field strength element (HFSE) fractionation. The variation in absolute
abundances of trace elements correlates closely with the major element composition of the clinopyroxene, with the most enriched
clinopyroxene having the lowest Mg# and highest Al contents. The problem is that the amount of crystal fractionation required to explain the major element variation
(∼20%) in these clinopyroxene phenocrysts cannot explain the increase in the abundance of the incompatible trace elements,
which would require more than 70% crystal fractionation, if constant partition coefficients are assumed. The anomalous increase
in incompatible trace elements appears to reflect an increase in their partition coefficients with increasing AlIV in the clinopyroxene; with an increase in Al2O3 from 1.5 to 4.0 wt.% during ∼20% crystal fractionation over a temperature decrease of ∼100°C being associated with more that
a threefold increase in the partition coefficients of Th, Zr, REE, and Y. The magnitude of these increases may indicate that
the substitution of these trace elements into clinopyroxene is better modeled in some natural systems by a local charge balance
model, rather than the distributed charge model that better replicates the results of annealed experiments. These findings
indicate that the effect of Al on the partition coefficients of incompatible trace elements in clinopyroxene may be under
appreciated in natural magmatic systems and that the application of experimentally determined clinopyroxene partition coefficients
to natural systems must be done with caution. 相似文献
34.
广东省22个燕山期花岗岩的源区特征及成因：元素及Nd-Sr同位素研究 总被引：4，自引：3，他引：4
根据主要元素组成,将所研究的22个广东省燕山期花岗岩分为强过铝花岗岩和弱过铝花岗岩两类,后者又区分出分异和未分异两种。它们总体具有较为相似的微量元素和稀土元素组成,即都是以大离子元素明显富集、Ba,Sr,Nb,Ta,P与 Ti 呈负异常、Eu 亏损为特征,但分异弱过铝花岗岩(包括禾洞、大埔、荷泗、白浆岩体)的 Ba、Ti 呈负异常和 Eu 亏损更为明显。强过铝和弱过铝花岗岩的 Nd 同位素组成区别明显:象头山等6个强过铝花岗岩体具有低的ε_(Nd)(t)值(-13.4～-10.0,平均为-12.1)和较老的 Nd 模式年龄(1.76～2.08Ga,平均为1.96Ga),是由成熟度较高的陆壳部分熔融形成;在弱过铝花岗岩中,石背岩体以及禾洞和大埔两个分异岩体具有高的ε_(Nd)(t)值(-3.6～-4.9,平均为-4.4)和年轻的 Nd 模式年龄(1.23 ～1.34Ga,平均为1.3Ga),反映其源区存在一定数量的地幔物质;佛冈等其余12个弱过铝花岗岩体(包括荷泗、白浆2个分异花岗岩)的ε_(Nd)(t)值(-12.3～-8.1,平均为-9.7)和 Nd 模式年龄(1.56～1.94Ga,平均为1.74Ga)都介于上述两类花岗岩之间,但相对较接近于强过铝花岗岩,主要是由成熟度不同程度地低于强过铝花岗岩源区的陆壳变质岩部分熔融形成。广东省燕山期花岗岩主要是在伸展构造及玄武岩底侵条件下,由以沉积变质岩为主的中下陆壳部分熔融形成。 相似文献
35.
Al-containing MgSiO3 perovskites of four different compositions were synthesized at 27 GPa and 1,873 K using a Kawai-type high-pressure apparatus:
stoichiometric compositions of Mg0.975Si0.975Al0.05O3 and Mg0.95Si0.95Al0.10O3 considering only coupled substitution Mg2+ + Si4+ = 2Al3+, and nonstoichiometric compositions of Mg0.99Si0.96Al0.05O2.985 and Mg0.97Si0.93Al0.10O2.98 taking account of not only the coupled substitution but also oxygen vacancy substitution 2Si4+ = 2Al3+ + VO¨. Using the X-ray diffraction profiles, Rietveld analyses were performed, and the results were compared between the stoichiometric
and nonstoichiometric perovskites. Lattice parameter–composition relations, in space group Pbnm, were obtained as follows. The a parameters of both of the stoichiometric and nonstoichiometric perovskites are almost constant in the X
Al range of 0–0.05, where X
Al is Al number on the basis of total cation of two (X
Al = 2Al/(Mg + Si + Al)), and decrease with further increasing X
Al. The b and c parameters of the stoichiometric perovskites increase linearly with increasing Al content. The change in the b parameter of the nonstoichiometric perovskites with Al content is the same as that of the stoichiometric perovskites within
the uncertainties. The c parameter of the nonstoichiometric perovskites is slightly smaller than that of the stoichiometric perovskites at X
Al of 0.10, though they are the same as each other at X
Al of 0.05. The Si(Al)–O1 distance, Si(Al)–O1–Si(Al) angle and minimum Mg(Al)–O distance of the nonstoichiometric perovskites
keep almost constant up to X
Al of 0.05, and then the Si(Al)–O1 increases and both of the Si(Al)–O1–Si(Al) angle and minimum Mg(Al)–O decrease with further
Al substitution. These results suggest that the oxygen vacancy substitution may be superior to the coupled substitution up
to X
Al of about 0.05 and that more Al could be substituted only by the coupled substitution at 27 GPa. The Si(Al)–O1 distance and
one of two independent Si(Al)–O2 distances in Si(Al)O6 octahedra in the nonstoichiometric perovskites are always shorter than those in the stoichiometric perovskite at the same
Al content. These results imply that oxygen defects may exist in the nonstoichiometric perovskites and distribute randomly. 相似文献
36.
M. D.?AlbaEmail author M. A.?Castro M.?Naranjo A. C.?Perdigón 《Physics and Chemistry of Minerals》2004,31(4):195-202
The main objective of this paper is to apply an NMR-based methodology to clay minerals that provides resolution enhancement in 27Al NMR spectra, permitting the differentiation of aluminum ions with one same coordination number, but with different chemical environments. For this purpose, we have performed two-dimensional 1H27Al cross-polarization experiments, which facilitate the identification of the different aluminum crystallographic sites by means of the nature of the proton polarization source. For the development of this methodology, we have carried out a systematic study of a set of well-characterized 2:1 phyllosilicates with aluminum in different crystallographic sites. The structural locations of aluminum in the selected layered silicates have been established unequivocally. Once the correlation between all different aluminum and proton sites in smectite was well established, an unknown material was examined, the utility of this methodology being illustrated. This methodology can be applied to a great variety of materials, such as zeolites, ALPOs and mesoporous aluminosilicates, in which a precise determination of the aluminum location is demanded. 相似文献
37.
A new phase of AlOOH (tentatively called δ-AlOOH) was synthesized at 21?GPa and 1000?°C and its crystal structure was identified by a powder X-ray diffraction method. Rietveld refinement revealed that this aluminum oxide hydroxide has an orthorhombic unit cell, a?=?4.7134(1) Å, b?=?4.2241(1) Å, c?=?2.83252(8) Å, V?=?56.395 (5) Å3, and Z?=?2 in the space group of P21?nm. A calculated density is 3.533?g?cm?3, which is about 4.48 and 15.04% denser than that of diaspore and boehmite, respectively. The δ-[Al0.86Mg0.07Si0.07]OOH is also stable at 21?GPa and 1000?°C, coexisting with majorite and phase egg, and its cell parameters are a?=?4.710(1) Å, b?=?4.215(1) Å, c?=?2.839(1) Å, and V?=?56.37(1) Å3. 相似文献
38.
Based on the connectivity relations among tetrahedron sites and the NMR spectra, we propose an ordered distribution of aluminum
atoms in the framework of analcime with space groups of Pbcb and Pcaa. The symmetries of the ordered distributions are formally
the same as Pcca. These symmetries are much lower than those reported by others such as Ia3d, I41/acd, Ibca, and I2/a. The lowering of symmetry results apparently from the fact that aluminum atoms in the framework of analcime
were strictly discriminated from silicon atoms. Dependence of the populations of Si(nAl)s upon Al content was estimated from 29Si MAS NMR, and can be successfully simulated by the ordered distributions. In the simulation, a small number of defects in
the Al distribution were introduced into the ordered distribution mainly to adjust the deviation of Al content per unit cell
from the typical composition. Analysis of the powder X-ray diffraction patterns of analcime was carried out, which suggests
that the space groups proposed in the present work offer a better fit than the ones reported previously.
Received: 5 April 1997 / Revised, accepted: 12 March 1998 相似文献
39.
通过电磁感应炉制备了含锶6A02铝合金,对制备的试样采用OM、XRD、硬度测试、拉伸测试,研究Sr含量对6A02铝合金组织和性能的影响。结果表明Sr元素的加入可以细化合金的铸态组织,改变组织形貌。当Sr含量为0.5%时,细化效果最好,合金其力学性能最优。随着Sr含量的增加,6A02铝合金出现新相Al_4Sr,随着组织中Al_4Sr相增多,Mg_2Si相的析出减少,减弱了对合金的强化效果,合金的力学性能呈下降趋势。 相似文献
40.
山东半岛近岸大气降水中的铝 总被引：4，自引：0，他引：4
根据1991－1995年间在黄海西北部的千里岩和青岛的八关山采集的雨水样品，对山东半岛近岸大气降水中铝的含量及其分布持征和影响因素进行了研究，结果表明，该区大气降水中的铝主要来自降水对陆源大气溶胶的淋洗和冲刷，具有显著的时空分布特异性，冬春季高于夏秋季，沿岸城市地带则高于远离陆地的海区，人文活动，气象条件及降水pH值是影响该地区大气降水中铝量的主要因素，通量计算显示大气沉降是陆源的铝向西北黄海输送的重要途径。 相似文献