A1416从选硼后母液中萃取硼酸研究   总被引：10，自引：0，他引：10  

唐明林  邓天龙 《盐湖研究》1994,2(1):63-66

本文详细报道了利用Ａ１４１６萃取剂选硼后母液中萃取硼酸的研究结果．Ａ１４１６对硼酸选择性高，总回收率８３．８０％，制得了高纯度硼酸产品。  相似文献   

On the metal content and metal ion uptake of botanically specific peats and the derived humic acids     

Raymond Bonnett  Richard P.C. Cousins 《Organic Geochemistry》1987,11(6)

With respect to ten metals (Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga) which are continguous in the Periodic Table the natural metal content and the ability to take up metal ions has been determined for three peats of defined botanical origin, each peat being sampled at three different levels. A correlation is found between the natural metal content and botanical origin. Apart from aluminium, the concentration of individual metals increased in the series Sphagnum < fen sedge < reed, the increase being statistically significant (P = 0.001) for V, Mn, Co, Ni, and Ga and for the sum of the metal ions measured.No clear correlation emerged between botanical origin and metal uptake. The metal uptake by the humic acid derived from each peat sample was also determined, and correlated with the metal uptake of the source peat itself.In all the humic acid and peat metal-uptake experiments the selectivities were very similar. V, Cr, Cu, Ga were readily taken up while Mn, Co and Zn were consistently less preferred.  相似文献   

Acid catalysis of alkyl hydrogen exchange and configurational isomerisation reactions: acyclic isoprenoid acids     

Alfons V. Larcher  Robert Alexander  Steven J. Rowland  Robert I. Kagi 《Organic Geochemistry》1986,10(4-6)

Acid-catalysed alkyl hydrogen exchange and configurational isomerisation has been studied in a series of acyclic isoprenoid acids when they were heated at 160°C in the presence of a montmorillonite. Hydrogen exchange occurred between the adsorbed water of the clay surface and the a position of the isoprenoid acids. In cases where this position was chiral, exchange was accompanied by configurational isomerisation. Configurational isomerisation occurred more slowly in experiments conducted without a clay matrix in the presence of water. These results have been rationalized in terms of a reaction mechanism involving protonation of the carbonyl oxygen causing enolization and consequent hydrogen exchange at the a position of the acids. This mechanism was used to account for the relatively fast rate of isomerisation of C-2 chiral centres in sedimentary acyclic isoprenoid acids during maturation.  相似文献   

The reaction of ozone with isolated aquatic fulvic acid     

Linda J. Anderson  J.Donald Johnson  Russell F. Christman 《Organic Geochemistry》1985,8(1):65-69

Aquatic fulvic acid, isolated from a North Carolina bay lake, was reacted with ozone, an alternative oxidant in drinking water treatment. Ozonated samples were acidified, extracted with ether, dried, concentrated, and methylated prior to GC-MS analysis. Identified reaation products include mono-, di- and tribasic aliphatic acids and benzene tricarboxylic acids. The products with the highest relative concentrations were succinic and malonic acid, although all products were at relatively low concentration levels. Many of the products identified in this study have also been seen among the reaction products of fulvic acid and other oxidants, such as Cl₂, CIO₂ and KMnO₄.  相似文献   

Thermal characterization of natural and synthetic humic substances     

P. Ioselis  Y. Rubinsztain  R. Ikan  Z. Aizenshtat  M. Frenkel 《Organic Geochemistry》1985,8(1):95-101

Thermogravimetric technique was used for the characterization of natural (humic) and synthetic (melanoidins) substances. The influence of pH on the thermal stability of humic substances was studied. A similarity in thermal behaviour of natural humic substances and of melanoidins (prepared from an excess of sugar) and the unique thermal properties of melanoidins (prepared from basic amino acids) was observed. Thermal behavior of natural and synthetic substances was compared with model compounds of sugar, peptide and kerogen types.  相似文献   

Low levels of aluminium causing death of brown trout (salmo trutta fario,L.) in a Swiss alpine lake     

Daniel Dietrich  Ch. Schlatter 《Aquatic Sciences - Research Across Boundaries》1989,51(4):279-295

Several attempts to stock fish in acidified alpine lakes have so far proven unsuccessful. In an effort to investigate the problems associated with the stocking of fish, the Swiss alpine Lake Laiozza was chosen for experimentation. An analysis of Lake Laiozza water revealed low ion concentrations (0.5 mg Ca/L, 0.13 mg Na/L, 0.02 mg Cl/L), moderate aluminium concentrations (121 ± 28 µg Al/L), and a moderately low pH (5.41 ± 0.21). As in common practice, one and two year old brown trout were exposed in a closed keep-net in Lake Laiozza. The water of Lake Laiozza proved to be acutely toxic to the fish. Mucous clogging of the gills, gill epithelial damage, plasma electrolyte losses, and high hematocrits were the predominant symptoms observed. All symptoms observed are typical for an acute intoxication with aluminium. This stands in contrast to the generally accepted view that aluminium concentrations lower than 200 µg Al/L should not be toxic to brown trout at a pH 5.4. The low Na and Cl and low Ca concentrations in the Lake Laiozza water seem to have rendered the fish much more susceptible to aluminium intoxication.  相似文献   

Measurements of the HONO photodissociation constant     

K. J. Wall  C. L. Schiller  G. W. Harris 《Journal of Atmospheric Chemistry》2006,55(1):31-54

Measurements of the photodissociation constant for nitrous acid (j _HONO) were made at an urban site in Toronto, Canada, during the months of May–July 2005, using an optically thin actinometer. Operating details of the j _HONO monitor are reported, along with laboratory tests. Measurements of j _HONO were obtained for solar zenith angles ranging from 20–75^∘, under clear and cloudy skies. Maximum error estimates on j _HONO under clear skies range from 11% at sunrise, to 4% at solar noon, with a minimum detection limit of 5.7 × 10⁻⁴/sec for our actinometer. Measured clear-sky values of j _HONO were compared with values calculated by a four-stream discrete ordinate radiative transfer (RT) model (ACD TUV version 4.1), and were found to be within better than 10% agreement for solar zenith angles < 65^∘. For conditions of scattered cloud, enhancement and suppression of the j _HONO values occurred by as much as 16%–70%, and 59%–80%, respectively. The integrated band area of the nπ^∗ transition for gas-phase nitrous acid yields an oscillator strength, f = (1.06 ± 0.044)×10⁻³ (based on clear-sky data), 19.1% higher than the value reported by Bongartz et al. (1991).  相似文献   

A method for determining thermophysical properties of organic material in aqueous solutions: Succinic acid     

I. Riipinen  B. Svenningsson  M. Bilde  A. Gaman  K.E.J. Lehtinen  M. Kulmala 《Atmospheric Research》2006,82(3-4):579

A method for determining evaporation rates and thermodynamic properties of aqueous solution droplets is introduced. The method combines evaporation rate measurements using modified TDMA technique with data evaluation using an accurate evaporation model. The first set of data has been collected and evaluated for succinic acid aqueous solution droplets.Evaporation rates of succinic acid solution droplets have been measured using a TDMA system at controlled relative humidity (65%) and temperature (298 K). A temperature-dependent expression for the saturation vapour pressure of pure liquid phase succinic acid at atmospheric temperatures has been derived by analysing the evaporation rate data with a numerical model. The obtained saturation vapour pressure of liquid phase succinic acid is ln(p) = 118.41 − 16204.8/T − 12.452ln(T). The vapour pressure is in unit of Pascal and the temperature in Kelvin. A linear expression for the enthalpy of vaporization for liquid state succinic acid is also presented.According to the results presented in the following, a literature expression for the vapour pressure of liquid phase succinic acid defined for temperatures higher than 461 K [Yaws, C.L., 2003. Yaws' Handbook of Thermodynamic and Physical Properties of Chemical Compounds, Knovel] can be extrapolated to atmospheric temperatures with very good accuracy. The results also suggest that at 298 K the mass accommodation coefficient of succinic acid is unity or very close to unity.  相似文献   

Sulfate-coated dust particles in the free troposphere over Japan   总被引：1，自引：0，他引：1  

Tomoko Kojima  Peter R. Buseck  Yasunobu Iwasaka  Atsushi Matsuki  Dmitri Trochkine   《Atmospheric Research》2006,82(3-4):698

Airborne aerosol collections were performed over Wakasa bay (36°00′N, 135°30′E) in March and Kumano open sea (34°00′N, 136°50′E) and Seto (35°10′N, 137°10′E) in July 2001 at altitudes between 1.0 and 5.8 km. The particles were individually analyzed using transmission electron microscopy (TEM). Relatively large mineral-dust (mostly clay) particles were abundant in the March samples. They also dominated in July in the mid-troposphere higher than 4 km altitude, whereas sea salt and ammonium sulfate were more abundant at lower altitudes. Ca-coated grid samples show many traces of aqueous sulfate droplets. The proportions of former sulfate droplets to the total collected particles apparently increased with increasing relative humidity at the time of sampling. TEM analysis revealed that a significant fraction of these former droplets enclose mineral-dust particles as well as sea salt, soot, and fly ash. Some enclose mixtures of mineral-dust, sea-salt, soot, and fly ash particles. The results provide evidence that mineral dust from the Asian continent could acquire coatings of sulfate while being transported in the free troposphere. The mineral-dust particles probably acquired the sulfate coatings either through heterogeneous uptake of gaseous SO₂ and subsequent oxidation or through coagulation with cloud or fog droplets. The presence of the mixed particles in sulfate droplets also indicates that aggregation of particles of different origins occurred through cloud processing. Such sulfate-coated dust particles would affect cloud formation, precipitation, and chemistry of the free troposphere.  相似文献   

Modeling and predicting of drainage quality for sulfide mine tailings impoundments     

Kaixuan TAN Zhwngji YI Aili TAN Liangshu XIA 《中国地球化学学报》2006,25(B08):28-29

Effluent from tailings impoundments of sulfide mine is an important environmental problem. The oxidation of sulfide minerals in tailings impoundments and consequent release of acid and contaminants, including heavy metals and arsenic, to tailings pore-water can last for decades to centuries. Pollution of water bodies including surface water and groundwater occurs when infiltration of precipitation is unhindered, bottom liners are absent and no drainage collection is installed. So there is a great need to develop reliable modeling techniques for characterizing geochemical interactions taking place within the tailings and predicting potential future environmental hazard which favor further prevention and remediation of the acidic mine drainage （AMD）. In this paper, a comprehensive dynamic model for tailings-water interaction was established on the basis of considering the coupling and feedback among many factors and processes such as sulfide oxidation, gangue dissolution, oxygen diffusion, water flow and mass transport,  相似文献