Co-precipitation of plutonium(IV) and americium(III) from nitric acid-oxalic acid solutions with bismuth oxalate

International Nuclear Information System (INIS)

Pius, I.C.; Noronha, D.M.; Chaudhury, Satyajeet

2017-01-01

Co-precipitation of plutonium and americium from nitric acid-oxalic acid solutions with bismuth oxalate has been investigated for the removal of these long lived α-active nuclides from waste solutions. Effect of concentration of bismuth and oxalic acid on the co-precipitation of Pu(IV) from 3 M HNO_3 has been investigated. Similar experiments were also carried out from 3.75 M HNO_3 on co-precipitation of Am(III) to optimize the conditions of precipitation. Strong co-precipitation of Pu(IV) and Am(III) with bismuth oxalate indicate feasibility of treatment of plutonium and americium bearing waste solutions. (author)

Study of precipitation behaviour of Mo and Zr in nitric acid solution

International Nuclear Information System (INIS)

Lin Cansheng; Wang Xiaoying; Zhang Chonghai

1992-01-01

The precipitation behaviour of Mo and Zr which depends on the concentrations of Mo, Zr, nitric acid and temperature is studied. Precipitation, post-precipitation and ultracentrifugation experiments are made at 100 deg C, 80 deg C, 60 deg C, 40 deg C and room temperatures in the range of 0.6-6.0 mol/1 nitric acid. The experimental feeds are made up of molybdenum labelled with 99 Mo, zirconium labelled with 95 Zr and nitric acid solution. The feed is allowed to stand at constant temperature for some time for the observation of precipitation behaviour. The filtered precipitate and ultracentrifuged liquid is to be measured with HP (Ge)-multichannel analyser in order to determine the content of Mo, Zr and their mole ration in the precipitate and to find out whether there is colloid in the liquid. The results show that the mixed solution of Mo and Zr can produce precipitate and post-precipitate in nitric acid. If the filtrated liquid is allowed to stand for some time, precipitate can be produced again, until the concentration of Mo and Zr in the feed is too low to form precipitate, such as 2.5 x 10 -3 mol/1. If the concentration of nitric acid is less than 4.0 mol/1, the precipitation is produced easily and more precipitate is formed. Precipitation is slower in solutions which are more than 4.0 mol/1 in HNO 3 . The mole-ratio of Mo to Zr in the precipitate is 2 to 1 and it is not dependent on that ratio in the system

Properties of precipitates formed during ammonization of extractional phosphoric acid

International Nuclear Information System (INIS)

Zakharova, B.S.; Komissarova, L.N.; Naumov, S.V.; Traskin, V.Yu.

1992-01-01

Dimensions of precipitated rare-earth phosphate particles -(0.1 μm)- are near the boundary of colloidal system sedimentation stability range at neutralization of extraction phosphoric acid. Thus, formation of multiple aggregates of colloidal particles results in immediate sedimentation of the precipitate. Processes occurring within the system may be described using second order reaction equation. Average efficient size of precipitates grows at reduction of reaction mixture pH. About 30% of rare-earth elements and yttrium in the extraction phosphoric acid is extracted from it; concentration of rare-earth elements, yttrium and scandium in precipitate is maximum 2 mass. %

Plasmodium falciparum-Derived Uric Acid Precipitates Induce Maturation of Dendritic Cells

Science.gov (United States)

van de Hoef, Diana L.; Coppens, Isabelle; Holowka, Thomas; Ben Mamoun, Choukri; Branch, OraLee; Rodriguez, Ana

2013-01-01

Malaria is characterized by cyclical fevers and high levels of inflammation, and while an early inflammatory response contributes to parasite clearance, excessive and persistent inflammation can lead to severe forms of the disease. Here, we show that Plasmodium falciparum-infected erythrocytes contain uric acid precipitates in the cytoplasm of the parasitophorous vacuole, which are released when erythrocytes rupture. Uric acid precipitates are highly inflammatory molecules that are considered a danger signal for innate immunity and are the causative agent in gout. We determined that P. falciparum-derived uric acid precipitates induce maturation of human dendritic cells, increasing the expression of cell surface co-stimulatory molecules such as CD80 and CD86, while decreasing human leukocyte antigen-DR expression. In accordance with this, uric acid accounts for a significant proportion of the total stimulatory activity induced by parasite-infected erythrocytes. Moreover, the identification of uric acid precipitates in P. falciparum- and P. vivax-infected erythrocytes obtained directly from malaria patients underscores the in vivo and clinical relevance of our findings. Altogether, our data implicate uric acid precipitates as a potentially important contributor to the innate immune response to Plasmodium infection and may provide a novel target for adjunct therapies. PMID:23405174

Arsenic removal from acidic solutions with biogenic ferric precipitates.

Science.gov (United States)

Ahoranta, Sarita H; Kokko, Marika E; Papirio, Stefano; Özkaya, Bestamin; Puhakka, Jaakko A

2016-04-05

Treatment of acidic solution containing 5g/L of Fe(II) and 10mg/L of As(III) was studied in a system consisting of a biological fluidized-bed reactor (FBR) for iron oxidation, and a gravity settler for iron precipitation and separation of the ferric precipitates. At pH 3.0 and FBR retention time of 5.7h, 96-98% of the added Fe(II) precipitated (99.1% of which was jarosite). The highest iron oxidation and precipitation rates were 1070 and 28mg/L/h, respectively, and were achieved at pH 3.0. Subsequently, the effect of pH on arsenic removal through sorption and/or co-precipitation was examined by gradually decreasing solution pH from 3.0 to 1.6 (feed pH). At pH 3.0, 2.4 and 1.6, the highest arsenic removal efficiencies obtained were 99.5%, 80.1% and 7.1%, respectively. As the system had ferric precipitates in excess, decreased arsenic removal was likely due to reduced co-precipitation at pHremoves iron and arsenic from acidic solutions, indicating potential for mining wastewater treatment. Copyright © 2015 Elsevier B.V. All rights reserved.

Impact of acid precipitation on freshwater ecosystems in Norway

Energy Technology Data Exchange (ETDEWEB)

Wright, R F; Dale, T; Gjessing, E T; Hendrey, G R; Henriksen, A; J Hannesen, M; Muniz, I P

1975-01-01

Precipitation in southern Norway contains large amounts of H/sup +/, SO/sub 4//sup 2 -/, and NO/sub 3//sup -/ ions, along with heavy metals such as Cu, Zn, Cd, and Pb. These pollutants are transported over long distances to Scandinavia and are deposited in precipitation and dry-fallout. Large areas of southern Norway have been adversely affected by acid precipitation. The pH of many lakes is below 5.0 and sulfate, rather than bicarbonate, is the major anion. Lakes in these areas are particularly vulnerable to acid precipitation because their watersheds are underlain by highly resistant bedrock with low calcium and magnesium contents. The effects of the increasing acidity of freshwater ecosystems involve interference at every trophic level. Biological surveys indicate that low pH-values inhibit the decomposition of allochthonous organic matter, decrease the species number of phyto- and zooplankton and benthic invertebrates, and promote the growth of benthic mosses. Fish populations have been severely affected - the salmon have been eliminated from many rivers, and hundreds of lakes have lost their sport fisheries.

Acid precipitation; an annotated bibliography

Science.gov (United States)

Wiltshire, Denise A.; Evans, Margaret L.

1984-01-01

This collection of 1660 bibliographies references on the causes and environmental effects of acidic atmospheric deposition was compiled from computerized literature searches of earth-science and chemistry data bases. Categories of information are (1) atmospheric chemistry (gases and aerosols), (2) precipitation chemistry, (3) transport and deposition (wet and dry), (4) aquatic environments (biological and hydrological), (5) terrestrial environments, (6) effects on materials and structures, (7) air and precipitation monitoring and data collection, and (8) modeling studies. References date from the late 1800 's through December 1981. The bibliography includes short summaries of most documents. Omitted are unpublished manuscripts, publications in press, master 's theses and doctoral dissertations, newspaper articles, and book reviews. Coauthors and subject indexes are included. (USGS)

Acid precipitation and forest vegetation

Energy Technology Data Exchange (ETDEWEB)

Tamm, C O; Cowling, E B

1977-04-01

Effects of acidic precipitation on forest vegetation may be classified as being either direct or indirect. Among the most important direct effects are damage to protective cuticular layers, interference with normal functioning of guard cells, poisoning of plant cells after diffusion of acidic substances through stomata or cuticle and interference with reproductive processes. Indirect effects include accelerated leaching of substances from foliar organs, increased susceptibility to drought and other environmental stress factors, and alteration of symbiotic associations and host-parasite interactions. The potential importance of nutrient uptake through foliage and the need to understand atmosphere-plant-soil interactions are stressed.

Impact of acid precipitation on recreation and tourism in Ontario: an overview

Energy Technology Data Exchange (ETDEWEB)

1984-01-01

The impacts of acid precipitation on fishing opportunities, waterfowl and moose hunting, water contact activities, and the perception of the environment in Ontario are analyzed. Economic effects and future research needs are also estimated and discussed. These questions have been examined by identifying the likely links between acidic precipitation and recreation and tourism, by developing estimates of the importance of aquatic-based recreation and tourism, by describing the current and estimated future effects of acid precipitation. 101 references, 9 figures, 19 tables.

Fabrication of Times and Micro-Formation of Discourse at a Secondary School

Directory of Open Access Journals (Sweden)

Michalis Kontopodis

2007-01-01

Full Text Available The paper presented here starts with a reference to modernist time theories, followed by a presentation of alternative views in the works of FOUCAULT, DELEUZE, LATOUR and others. The study concentrates on the concrete context of an experimental school aiming at incorporation of excluded students into society. Based on the synthesis of discourse analysis and Actor-Network-Theory, the study puts forward a twofold question: a whether and how the "fabrication of times" is interrelated to micro-formations of discourses and b how micro-formations of discourses emerge as processes in the concrete setting of a school in regard to their temporal and other aspects. To answer this query, I combine some critical ethnographic work with an Actor-Network-Theory methodology—an approach which could be regarded as "rhizomatic analysis" (DELEUZE & GUATTARI, 1980. Examining discursive and non-discursive action with a particular focus on materialities (sites, students' documents, educational reports, CVs, and files, I introduce the notion of "temporal devices of control" and map two of them: that of synchronicity and that of convergence. In this way, I propose a new understanding of time and relate it to discourse formation. This, in turn, reveals a new potential for critical reflection on theories of time as well as on all action taking place in the school. URN: urn:nbn:de:0114-fqs0701119

Characteristics of a continuous denitration by formic acid - electrolytic trimming of residual acid with accompanying the precipitation of metal ions

International Nuclear Information System (INIS)

Kim, G. W.; Kim, S. H.; Lim, J. G.; Lee, I. H.

2003-01-01

This work has studied the characteristics of destruction of nitric acid and precipitation of several metal ions in a continuous denitration process combining a denitration by formic acid and a residual acid-electrolytic trimming system. The metal ions of Zr, Mo, Fe, and Nd did not affect the electrodes at the step of electrolytic trimming of the residual acid after denitration by formic acid. The Mo ion in electrolytic solution enhanced the generation of nitrite ion during the electrolytic reaction. The mole ratio of formic acid to nitric acid fed into the continuous denitration reactor using formic acid affected much the final acidity, the precipitation yields of metal ions, the precipitate morphology. At the ratio of 1.65, the process had the lowest final acidity of less than 0.1 M, and the precipitation yields of Zr and Mo reached 95% and 83%, respectively as the highest values

Indium sulfide precipitation from hydrochloric acid solutions of calcium and sodium chlorides

International Nuclear Information System (INIS)

Kochetkova, N.V.; Bayandina, Yu.E.; Toptygina, G.M.; Shepot'ko, A.O.

1988-01-01

The effect of precipitation duration, acid concentration, indium complexing with chloride ions on the process of indium sulfide chemical precipitation in hydrochloric acid solutions, precipitate composition and dispersity are studied. It is established that indium sulfide solubility increases in solutions with acid concentration exceeding 0.40-0.45 mol/l. Calcium and indium chloride addition to diluted hydrochloric solutions greatly increases the solubility of indium sulfide. The effect of calcium chloride on In 2 S 3 solubility is higher than that of sodium chloride

Acid Precipitation Awareness Curriculum Materials in the Life Sciences.

Science.gov (United States)

Stubbs, Harriett S.

1983-01-01

Provides an outline of course content for acid precipitation and two acid rain activities (introduction to pH and effects of acid rain on an organism). Information for obtaining 20 additional activities as well as an information packet containing booklets, pamphlets, and articles are also provided. (JN)

Tracing of salicylic acid additive during precipitation of zirconium

International Nuclear Information System (INIS)

Bharati Misra, U.; Gopala Krishna, K.; Narasimha Murty, B.; Yadav, R.B.

2011-01-01

This paper presents the results of experimental study carried out to know whether the salicylic acid used as an additive during the precipitation of zirconium using ammonium hydroxide solution goes into the filtrate, remains in the hydrated zirconia or gets distributed between the both under the ambient conditions of precipitation. Keeping its simplicity and amenability to adopt on a routine basis, spectrophotometric method has been chosen for the purpose among the many methods available and the problems associated in determining salicylic acid in the presence of zirconium and the medial measures to circumvent the same have been brought out in detail. (author)

Precipitation stripping of neodymium from carboxylate extractant with aqueous oxalic acid solutions

International Nuclear Information System (INIS)

Konishi, Yasuhiro; Asai, Satoru; Murai, Tetuya

1993-01-01

This paper describes a precipitation stripping method in which neodymium ions are stripped from carboxylate extractant in organic solvent and simultaneously precipitated with aqueous oxalic acid solution. For the single-stage process, a quantitative criterion for precipitating oxalate powders was derived theoretically, and stripping experiments were done under the precipitation conditions. The resultant precipitates were neodymium oxalate, which is completely free from contamination by the carboxylate extractant and the organic solvent. The overall rate of stripping was controlled by the transfer of neodymium carboxylate in the organic solution, indicating that the presence of oxalic acid in the aqueous phase has no effect on the stripping rate. These findings demonstrate the feasibility of combining the conventional stripping and precipitation stages in a solvent extraction process for separation and purification of rare earths

Acidic precipitation, Vol. 1: Case studies. Advances in environmental science

Energy Technology Data Exchange (ETDEWEB)

Adriano, D.C.; Havas, M. (eds.)

1989-01-01

As has been the case with many environmental issues of the twentieth century, acidic precipitation has its origin in emissions to the atmosphere of numerous compounds from both natural and man-made sources. This volume of the subseries Acidic precipitation emphasizes some of the classical interactions between acidic deposition and ecological effects. It covers the cycling, behavior, and effects of acidic components in nature. Included are the effects of acidic deposition on soil chemistry, soil solution chemistry, aquatic chemistry, forest productivity, and fish populations. Several major ecological consequences, such as a decline in forest productivity, soil and water acidification, depletion of fish populations, and slower litter decomposition are highlighted. A chapter is devoted to the comparative biogeochemistry of aluminum, encompassing several ecosystems in North America and Europe. Nine chapters have been processed separately for inclusion in the appropriate data bases.

Wet precipitators for sulphuric acid plants

International Nuclear Information System (INIS)

Ojanpera, R.O.

1989-01-01

Both the service requirements and design construction details have changed considerably in recent years for wet electrostatic precipitators as used for gas cleaning ahead of metallurgical sulphuric acid plants. Increased concern over acid quality has resulted in more emphasis on dust efficiencies compared to collection of acid mist. Also, higher static operating pressures have caused large structural loads on casing and internal components. In this paper these two issues are addressed in the following ways: Recognition that all dusts do not collect similarly. The mechanism by which various dusts collect affect the design of the entire wet gas cleaning system. Use of both traditional and newer materials of construction to accommodate the higher design pressures while still maintaining corrosion resistance

Arsenic removal from acidic solutions with biogenic ferric precipitates

Energy Technology Data Exchange (ETDEWEB)

Ahoranta, Sarita H., E-mail: sarita.ahoranta@tut.fi [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101 Tampere (Finland); Kokko, Marika E., E-mail: marika.kokko@tut.fi [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101 Tampere (Finland); Papirio, Stefano, E-mail: stefano.papirio@unicas.it [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101 Tampere (Finland); Özkaya, Bestamin, E-mail: bozkaya@yildiz.edu.tr [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101 Tampere (Finland); Department of Environmental Engineering, Yildiz Technical University, Davutpasa Campus 34220, Esenler, Istanbul (Turkey); Puhakka, Jaakko A., E-mail: jaakko.puhakka@tut.fi [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101 Tampere (Finland)

2016-04-05

Highlights: • Continuous and rapid arsenic removal with biogenic jarosite was achieved at pH 3.0. • Arsenic removal was inefficient below pH 2.4 due to reduced Fe–As co-precipitation. • As(V) had better sorption characteristics than As(III). • Biogenic jarosite adsorbed arsenic more effectively than synthetic jarosite. - Abstract: Treatment of acidic solution containing 5 g/L of Fe(II) and 10 mg/L of As(III) was studied in a system consisting of a biological fluidized-bed reactor (FBR) for iron oxidation, and a gravity settler for iron precipitation and separation of the ferric precipitates. At pH 3.0 and FBR retention time of 5.7 h, 96–98% of the added Fe(II) precipitated (99.1% of which was jarosite). The highest iron oxidation and precipitation rates were 1070 and 28 mg/L/h, respectively, and were achieved at pH 3.0. Subsequently, the effect of pH on arsenic removal through sorption and/or co-precipitation was examined by gradually decreasing solution pH from 3.0 to 1.6 (feed pH). At pH 3.0, 2.4 and 1.6, the highest arsenic removal efficiencies obtained were 99.5%, 80.1% and 7.1%, respectively. As the system had ferric precipitates in excess, decreased arsenic removal was likely due to reduced co-precipitation at pH < 2.4. As(III) was partially oxidized to As(V) in the system. In shake flask experiments, As(V) sorbed onto jarosite better than As(III). Moreover, the sorption capacity of biogenic jarosite was significantly higher than that of synthetic jarosite. The developed bioprocess simultaneously and efficiently removes iron and arsenic from acidic solutions, indicating potential for mining wastewater treatment.

The effect of acid precipitation on tree growth in eastern North America

Science.gov (United States)

Charles V. Cogbill

1976-01-01

Detailed study of the history of forest tree growth by tree-ring analysis is used to assess the effect of acid precipitation. The pattern and historical trends of acid precipitation deposition are compared with growth trends from mature forest stands in New Hampshire and Tennessee. No clear indication of a regional, synchronized decrease in tree growth was found. The...

36 CFR 1238.28 - What must agencies do when sending permanent microform records to a records storage facility?

Science.gov (United States)

2010-07-01

... 1232 of this chapter and the additional requirements in this section. (b) Package non-silver copies separately from the silver gelatin original or silver duplicate microform copy and clearly label them as non-silver copies. (c) Include the following information on the transmittal (SF 135 for NARA Federal Records...

Acidic precipitation. Volume 3: Sources, deposition, and canopy interactions. Advances in environmental science

Energy Technology Data Exchange (ETDEWEB)

Lindberg, S.E.; Page, A.L.; Norton, S.A. (eds.)

1990-01-01

As has been the case with many environmental issues of the twentieth century, acidic precipitation has its origin in emissions to the atmosphere of numerous compounds from both natural and man-made sources. This volume emphasizes the atmospheric aspects of acidic precipitation and all that this term has come to include (e.g. toxic gases such as ozone, trace metals, aluminum, and oxides of nitrogen). It progresses from emissions of the precursors of acidic precipitation to their eventual deposition on environmental surfaces. The chapters describe the sources of acidic and basic airborne substances, their interactions in the atmosphere and with rain droplets, and their reactions with other airborne constituents such as aluminum and other metals. Also discussed are the use of metals as tracers of sources of the precursors of acidic precipitation and as tracers of historical deposition rates, the processes controlling the removal of airborne material as dry deposition and deposition interactions with the forest canopy, and past and future trends in atmospheric emissions and options for their abatement.

Acid precipitation literature review

Energy Technology Data Exchange (ETDEWEB)

Seip, H M; Andersen, B; Andersson, G; Hov, Oe; Kucera, V; Moseholm, L

1986-01-01

There is an increasing number of publications on acid deposition and related phenomena. Interest in these topics has also been reflected in a considerable number of meetings and conferences in this field. The largest of these in 1985 was the ''International Symposium on Acidic Precipitation'' (Muskoka, Ontario). Most work so far has been carried out in North America and Europe. There is, however, an increasing interest in obtaining a better picture of sensitive areas and possible acidification in other parts of the world. Anthropogenic SO/sub 2/ emissions have been estimated to be (in TgSyr/sup -1/): 2.4 (Africa), 4.1 (South America), 0.7 (Ocenia), and 18.3 (Asia). The largest increase during the last decade has been in Asia. Based on Studies of precipitation in remote areas it has been suggested that the natural background concentration for sulphate in many areas should be about 6 ..mu..eq 1/sup -1/. A new study of sulphate and nitrate in Greenland snow showed that both ions increased by a factor of about 2 from 1895 to 1978. The concentrations of SO/sub 2/ at Norwegian rural sites show a decreasing trend since late 1970s, while concentrations of sulphate in air show no clear trend. More reliable models for transformation, transport and deposition of chemicals are being developed, including three-dimensional grid models to describe episodes of elevated pollution levels lasting for a few days. Model calculations indicate that control of hydrocarbon (HC) emissions is much more efficient in reducing the ozone level in southern Scandinavia in episodes influenced by long-range transported pollutants than NO/sub x/ control of combined NO/sub x/ and HC control. 36 refs. (EG).

Long range transport of air pollutants in Europe and acid precipitation in Norway

Science.gov (United States)

Jack Nordo

1976-01-01

Observations show that pollutants from large emission sources may cause significant air concentrations 500 to 1000 miles away. Very acid precipitation occurs in such periods. The scavenging is often intensified by the topography. Case studies will be presented, with special emphasis on acid precipitation in Scandinavia. Large scale dispersion models have been developed...

Acidic precipitation. Volume 4: Soils, aquatic processes, and lake acidification. Advances in environmental science

Energy Technology Data Exchange (ETDEWEB)

Norton, S.A.; Lindberg, S.E.; Page, A.L. (eds.)

1990-01-01

Acidic precipitation and its effects have been the focus of intense research for over two decades. Recently, research has focused on a greater understanding of dose-response relationships between atmospheric loading of acidifying material and lake acidity. This volume of the subseries Acidic Precipitation emphasizes acid neutralizing processes and the capacity of terrestrial and aquatic systems to assimilate acidifying substances and, conversely, the ability of systems to recover after acid loading diminishes. Eight chapters have been processed separately for inclusion in the appropriate data bases.

Measurement of material mechanical properties in microforming

Science.gov (United States)

Yun, Wang; Xu, Zhenying; Hui, Huang; Zhou, Jianzhong

2006-02-01

As the rapid market need of micro-electro-mechanical systems engineering gives it the wide development and application ranging from mobile phones to medical apparatus, the need of metal micro-parts is increasing gradually. Microforming technology challenges the plastic processing technology. The findings have shown that if the grain size of the specimen remains constant, the flow stress changes with the increasing miniaturization, and also the necking elongation and the uniform elongation etc. It is impossible to get the specimen material properties in conventional tensile test machine, especially in the high precision demand. Therefore, one new measurement method for getting the specimen material-mechanical property with high precision is initiated. With this method, coupled with the high speed of Charge Coupled Device (CCD) camera and high precision of Coordinate Measuring Machine (CMM), the elongation and tensile strain in the gauge length are obtained. The elongation, yield stress and other mechanical properties can be calculated from the relationship between the images and CCD camera movement. This measuring method can be extended into other experiments, such as the alignment of the tool and specimen, micro-drawing process.

Amphibian recovery after a decrease in acidic precipitation.

Science.gov (United States)

Dolmen, Dag; Finstad, Anders Gravbrøt; Skei, Jon Kristian

2018-04-01

We here report the first sign of amphibian recovery after a strong decline due to acidic precipitation over many decades and peaking around 1980-90. In 2010, the pH level of ponds and small lakes in two heavily acidified areas in southwestern Scandinavia (Aust-Agder and Østfold in Norway) had risen significantly at an (arithmetic) average of 0.14 since 1988-89. Parallel with the general rise in pH, amphibians (Rana temporaria, R. arvalis, Bufo bufo, Lissotriton vulgaris, and Triturus cristatus) had become significantly more common: the frequency of amphibian localities rose from 33% to 49% (n = 115), and the average number of amphibian species per locality had risen from 0.51 to 0.88. In two other (reference) areas, one with better buffering capacity (Telemark, n = 21) and the other with much less input of acidic precipitation (Nord-Trøndelag, n = 106), there were no significant changes in pH or amphibians.

Ten-year study on acid precipitation nears conclusion

International Nuclear Information System (INIS)

Olem, H.

1990-01-01

Results from the National Acid Precipitation Assessment Program (NAPAP) are discussed. Final results are contained in 26 state of the science reports. Seven of the reports provide information on acid rain and aquatic ecosystems. They describe the current state of acidic surface waters, watershed processes affecting surface water chemistry, historical evidence for surface water acidification, methods for forecasting future changes, and the response of acidic surface water to liming. Six areas of the country were found to be of special interest: southwest Adirondacks, New England, forested areas of the mid-Atlantic highlands, the Atlantic coastal plain, the northern Florida highlands, parts of northeastern Wisconsin and the Upper Peninsula of Michigan. Environmental effects, mitigation efforts and possible legislation are briefly discussed

Glycation inhibits trichloroacetic acid (TCA)-induced whey protein precipitation

Science.gov (United States)

Four different WPI saccharide conjugates were successfully prepared to test whether glycation could inhibit WPI precipitation induced by trichloroacetic acid (TCA). Conjugates molecular weights after glycation were analyzed with SDS-PAGE. No significant secondary structure change due to glycation wa...

Application of a precipitation method for uranium recovery from abu-zaabal phosphoric acid plant, Egypt

International Nuclear Information System (INIS)

El-hazek, N.M.T.; Hussein, E.M.

1995-01-01

Current industrial recovery of uranium from 30% phosphoric acid-produced by the dihydrate process-is based on solvent extraction method. Uranium recovery from concentrated phosphoric acid (45-52% p o5 ) produced by evaporation of the 30% acid or directly produced by the hemihydrate process, by solvent extraction is difficult to apply in practice. In addition to possible contamination of the acid by the organic solvents and/or their deterioration. This paper investigates the possibility of applying a precipitation method (Weterings and Janssen, 1985) for uranium recovery from both low (28% P 2 O 5 ) and high (48% P 2 O 5 ) concentration phosphoric acids produced by abu-zaabal phosphoric acid plant (Abuzaabal fertilizers and chemicals Co., Egypt). The 28% acid produced by H 2 SO 4 dihydrate method and the 48% acid produced by evaporation of the 28% acid The applied precipitation method depends on using NH 4 F as a uranium precipitant from both low and high concentration phosphoric acids in presence of acetone as a dispersing agent. All the relevant factors have been studied

Precipitation of plutonium from acidic solutions using magnesium oxide

International Nuclear Information System (INIS)

Jones, S.A.

1994-01-01

Plutonium (IV) is only marginally soluble in alkaline solution. Precipitation of plutonium using sodium or potassium hydroxide to neutralize acidic solutions produces a gelatinous solid that is difficult to filter and an endpoint that is difficult to control. If the pH of the solution is too high, additional species precipitate producing an increased volume of solids separated. The use of magnesium oxide as a reagent has advantages. It is added as a solid (volume of liquid waste produced is minimized), the pH is self-limiting (pH does not exceed about 8.5), and the solids precipitated are more granular (larger particle size) than those produced using KOH or NaOH. Following precipitation, the raffinate is expected to meet criteria for disposal to tank farms. The solid will be heated in a furnace to dry it and convert any hydroxide salts to the oxide form. The material will be cooled in a desiccator. The material is expected to meet vault storage criteria

Third generation capture system: precipitating amino acid solvent systems

NARCIS (Netherlands)

Sanchez Fernandez, E.; Misiak, K.; Ham, L. van der; Goetheer, E.L.V.

2013-01-01

This work summarises the results of the design of novel separation processes for CO2 removal from flue gas based on precipitating amino acid solvents. The processes here described (DECAB, DECAB Plus and pH-swing) use a combination of enhanced CO2 absorption (based on the Le Chatelier’s principle)

Effect of amino acids on the precipitation kinetics and Ca isotopic composition of gypsum

Science.gov (United States)

Harouaka, Khadouja; Kubicki, James D.; Fantle, Matthew S.

2017-12-01

Stirred gypsum (CaSO4 · 2H2O) precipitation experiments (initial Ωgypsum = 2.4 ± 0.14, duration ≈ 1.0-1.5 h) were conducted in the presence of the amino acids glycine (190 μM), L-alanine (190 μM), D- and L-arginine (45 μM), and L-tyrosine (200 μM) to investigate the effect of simple organic compounds on both the precipitation kinetics and Ca isotopic composition of gypsum. Relative to abiotic controls, glycine, tyrosine, and alanine inhibited precipitation rates by ∼22%, 27%, and 29%, respectively, while L- and D-arginine accelerated crystal growth by ∼8% and 48%, respectively. With the exception of tyrosine, amino acid induced inhibition resulted in fractionation factors (αs-f) associated with precipitation that were no more than 0.3‰ lower than amino acid-free controls. In contrast, the tyrosine and D- and L-arginine experiments had αs-f values associated with precipitation that were similar to the controls. Our experimental results indicate that Ca isotopic fractionation associated with gypsum precipitation is impacted by growth inhibition in the presence of amino acids. Specifically, we propose that the surface-specific binding of amino acids to gypsum can change the equilibrium fractionation factor of the bulk mineral. We investigate the hypothesis that amino acids can influence the growth of gypsum at specific crystal faces via adsorption and that different faces have distinct fractionation factors (αface-fluid). Accordingly, preferential sorption of amino acids at particular faces changes the relative, face-specific mass fluxes of Ca during growth, which influences the bulk isotopic composition of the mineral. Density functional theory (DFT) calculations suggest that the energetic favorability of glycine sorption onto gypsum crystal faces occurs in the order: (1 1 0) > (0 1 0) > (1 2 0) > (0 1 1), while glycine sorption onto the (-1 1 1) face was found to be energetically unfavorable. Face-specific fractionation factors constrained by

Studies on Pu(IV)/(III)-oxalate precipitation from nitric acid containing high concentration of calcium and fluoride ions

International Nuclear Information System (INIS)

Kalsi, P.K.; Pawar, S.M.; Ghadse, D.R.; Joshi, A.R.; Ramakrishna, V.V.; Vaidya, V.N.; Venugopal, V.

2003-01-01

Plutonium (IV)/(III) oxalate precipitation from nitric acid solution, containing large amount of calcium and fluoride ions was investigated. It was observed that direct precipitation of Pu (IV) oxalate from nitric acid containing large amount of calcium and fluoride ions did not give good decontamination of Pu from calcium and fluoride impurities. However, incorporation of hydroxide precipitation using ammonium hydroxide prior to Pu (IV) oxalate precipitation results into PuO 2 with much less calcium and fluoride impurities. Whereas, good decontamination from calcium and fluoride impurities could be obtained by employing Pu (III) oxalate precipitation directly from nitric acid containing large amount of calcium and fluoride ions. A method was also developed to recover Pu from the oxalate waste containing calcium and fluoride ions. (author)

Optimization of precipitation conditions of thorium oxalate precipitate

International Nuclear Information System (INIS)

Pazukhin, Eh.M.; Smirnova, E.A.; Krivokhatskij, A.S.; Pazukhina, Yu.L.; Kiselev, P.P.

1986-01-01

Thorium precipitation in the form of difficultly soluble oxalate has been investigated. The equation binding the concentration of metal with the nitric acid in the initial solution and quantity of a precipitator necessary for minimization of desired product losses is derived. The graphical solution of this equation for a case, when the oxalic acid with 0.78 mol/l concentration is the precipitator, is presented

Precipitation of plutonium from acidic solutions using magnesium oxide

International Nuclear Information System (INIS)

Jones, S.A.

1994-01-01

Magnesium oxide will be used as a neutralizing agent for acidic plutonium-containing solutions. It is expected that as the magnesium oxide dissolves, the pH of the solution will rise, and plutonium will precipitate. The resulting solid will be tested for suitability to storage. The liquid is expected to contain plutonium levels that meet disposal limit requirements

Dose-response functions for effects of acidic precipitation on vegetation

Energy Technology Data Exchange (ETDEWEB)

Jacobson, J S; Troiano, J J

1983-01-01

Research on the effect of sulfuric and nitric acids, as well as other substances, in rain on plant growth has focused on quantifying the relationship between doses of acids in precipitation and plant response. After eight years, there has been no direct demonstration of harmful effects to plants by ambient acidic rain in North America, and there remains considerable uncertainty about the potential risk to cultivated and native plants. Current efforts to describe the relationships between dose of acidity and effects on plants need better experimental approaches if the results are to be more relevant to actual field situations. Mechanistic models that describe the physiological and biochemical basis for effects of acidic rain on plants will be needed to provide confidence in the predictions of plant response. 34 references, 1 figure.

Biomediated Precipitation of Calcium Carbonate in a Slightly Acidic Hot Spring

Science.gov (United States)

Jiang, L.

2015-12-01

A slightly acidic hot spring named "Female Tower" (T=73.5 °C, pH=6.64) is located in the Jifei Geothermal Field, Yunnan Province, Southwest China. The precipitates in the hot spring are composed of large amounts of calcite, aragonite, and sulfur. Scanning electron microscopy (SEM) analyses revealed that the microbial mats were formed of various coccoid, rod-shaped, and filamentous microbes. Transmission electron microscopy (TEM) showed that the intracellular sulfur granules were commonly associated with these microbes. A culture-independent molecular phylogenetic analysis demonstrated that the majority of the bacteria in the spring were sulfur-oxidizing bacteria. In the spring water, H2S concentration was up to 60 ppm, while SO42- concentration was only about 10 ppm. We speculated that H2S might be utilized by sulfur-oxidizing bacteria in this hot spring water, leading to the intracellular formation of sulfur granules. In the meantime, this reaction increased the pH in the micron-scale microdomains, which fostered the precipitation of calcium carbonate in the microbial mats. The results of this study indicated that the sulfur-oxidizing bacteria could play an important role in calcium carbonate precipitation in slightly acidic hot spring environments.

Chemical composition and seasonal variation of acid deposition in Guangzhou, South China: Comparison with precipitation in other major Chinese cities

International Nuclear Information System (INIS)

Huang Deyin; Xu Yigang; Peng Pingan; Zhang Huihuang; Lan Jiangbo

2009-01-01

With the aim of understanding the origin of acid rains in South China, we analyzed rainwaters collected from Guangzhou, China, between March 2005 and February 2006. The pH of rainwater collected during the monitoring period varied from 4.22 to 5.87; acid rain represented about 94% of total precipitation during this period. The rainwater was characterized by high concentrations of SO 4 2- , NO 3 - , Ca 2+ , and NH 4 + . SO 4 2- and NO 3 - , the main precursors of acid rain, were related to the combustion of coal and fertilizer use/traffic emissions, respectively. Ca 2+ and NH 4 + act as neutralizers of acid, accounting for the decoupling between high SO 4 2- concentrations and relatively high pH in the Guangzhou precipitation. The acid rain in Guangzhou is most pronounced during spring and summer. A comparison with acid precipitation in other Chinese cities reveals a decreasing neutralization capacity from north to south, probably related to the role and origin of alkaline bases in precipitation. - A north-to-south decreasing trend in the neutralization capacity of precipitation in China

OCHRE PRECIPITATES AND ACID MINE DRAINAGE IN A MINE ENVIRONMENT

Directory of Open Access Journals (Sweden)

BRANISLAV MÁŠA

2012-03-01

Full Text Available This paper is focused to characterize the ochre precipitates and the mine water effluents of some old mine adits and settling pits after mining of polymetallic ores in Slovakia. It was shown that the mine water effluents from two different types of deposits (adits; settling pits have similar composition and represent slightly acidic sulphate water (pH in range 5.60-6.05, sulphate concentration from 1160 to 1905 g.dm-3. The ochreous precipitates were characterized by methods of X-ray diffraction analysis (XRD, scanning electron microscopy (SEM and B.E.T. method for measuring the specific surface area and porosity. The dominant phases were ferrihydrite with goethite or goethite with lepidocrocide.

Dissolution of oxalate precipitate and destruction of oxalate ion by hydrogen peroxide in nitric acid solution

International Nuclear Information System (INIS)

Kim, Eung-Ho; Chung, Dong-Yong; Park, Jin-Ho; Yoo, Jae-Hyung

2000-01-01

This study aims at developing an oxalate precipitation process, which is applicable to a partitioning of long-lived radionuclides from the high-level radioactive liquid waste. In order to achieve this, a study for decomposition-reaction of oxalic acid by hydrogen peroxide was first carried out. The decomposition rates of H 2 O 2 and oxalic acid increased with an increase of nitric acid concentration, and especially those decomposition rates steeply increased at more than 2 M HNO 3 . Based on this result, the decomposition kinetics of H 2 O 2 and oxalic acid were suggested in this work. Then, the dissolution of oxalate precipitate and the destruction of oxalate ion in the solution were examined. Oxalate precipitates were prepared by adding oxalic acid into a simulated radioactive waste containing 8 metallic elements. The precipitates obtained thereby were dissolved in various nitric acid concentrations and reacted with H 2 O 2 at 90degC. When the oxalates were completely dissolved, most of the oxalates were decomposed by adding H 2 O 2 , but in a slurry state the decomposition yield of the oxalate decreased with an increase of the slurry density in the solution. Such phenomenon was considered to be due to a catalytic decomposition of H 2 O 2 on a solid surface of oxalate and the decomposition mechanism was explained by a charge transfer from a surface of oxalate solid to H 2 O 2 , producing OH radicals which can destruct H 2 O 2 explosively. Accordingly, the experimental condition for the decomposition of the oxalate precipitates was found to be most favorable at 3 M HNO 3 under the initial concentrations of 0.2 M oxalate and 1 M H 2 O 2 . At 3M HNO 3 , oxalate precipitates could be safely and completely dissolved, and almost decomposed. Additionally, it was observed that the presence of ferric ion in the solution largely affects the decomposition rate of H 2 O 2 . This could be explained by a chain reaction of hydrogen peroxide with ferric ion in the solution

Acid precipitation and reproductive success of Ambystoma salamanders

Energy Technology Data Exchange (ETDEWEB)

Pough, R H; Wilson, R E

1976-01-01

The two species of mole salamander that occur in the Ithaca, New York, region (Ambystoma maculatum and A. jeffersonianum) breed in temporary ponds that are formed by accumulation of melted snow and spring rains. Water in many of these pools during the breeding season is acid; pH values as low as 3.5 have been measured. In laboratory experiments A. maculatum tolerated pHs from 6 to 10 and had greatest hatching success at pH 7 to 9. Ambystoma Jeffersonianum tolerated pH 4 to 8 and was most successful at pH 5 to 6. Mortality rose abruptly beyond the tolerance limits. The pH optimum shifted upward with increasing temperature for A. jeffersonianum and downward for A. maculatum. Judging from our laboratory studies, the acidity measured in breeding ponds should cause mortality in A. maculatum and permit normal development in A. jeffersonianum. In a four-year study of a large acidic vernal pond, 938 adult A. maculatum produced 486 metamorphosed juveniles (0.52 juvenile/adult), while 686 adult A. jeffersonianum produced 2157 juveniles (3.14 juveniles/adult). Because the effects of acid precipitation on the salamanders' breeding ponds are cumulative from year to year, profound changes in the salamander populations can be anticipated.

Acid precipitation and reproductive success of Ambystoma salamanders

Energy Technology Data Exchange (ETDEWEB)

Pough, F H; Wilson, R E

1977-03-01

The two species of mole salamander that occur in the Ithaca, New York, region (Ambystoma maculatum and A. jeffersonianum) breed in temporary ponds that are formed by accumulation of melted snow and spring rains. Water in many of these pools during the breeding season is acid; pH values as low as 3.5 have been measured. In laboratory experiments A. maculatum tolerated pHs from 6 to 10 and had greatest hatching success at pH 7 to 9. Ambystoma jeffersonianum tolerated pH 4 to 8 and was most successful at pH 5 to 6. Mortality rose abruptly beyond the tolerance limits. The pH optimum shifted upward with increasing temperature for A. jeffersonianum and downward for A. maculatum. Judging from our laboratory studies, the acidity measured in breeding ponds should cause mortality in A. maculatum and permit normal development in A. jeffersonianum. In a 4 yr study of a large, acidic vernal pond, 938 adult A. maculatum produced 486 metamorphosed juveniles (0.52 juvenile/adult), while 686 adult A. jeffersonianum produced 2157 juveniles (3.14 juveniles/adult). Because the effects of acid precipitation on the salamanders' breeding ponds are cumulative from year to year, profound changes in the salamander populations can be anticipated.

Effects of initial supersaturation on spontaneous precipitation of calcium carbonate in the presence of charged poly-L-amino acids.

Science.gov (United States)

Njegić-Dzakula, Branka; Falini, Giuseppe; Brecević, Ljerka; Skoko, Zeljko; Kralj, Damir

2010-03-15

Spontaneous precipitation of calcium carbonate was investigated in two precipitation systems: (1) with initial supersaturation lower than that corresponding to the solubility of amorphous calcium carbonate (ACC), at which vaterite precipitated, and (2) with initial supersaturation higher than that of ACC solubility, at which a mixture of calcite and vaterite was formed. After the addition of an acidic polypeptide, poly-L-glutamic acid (pGlu) or poly-L-aspartic acid (pAsp), into (1) a significant inhibition of nucleation, expressed as an increase in induction time, and growth of vaterite, perceived as a dead zone, was observed. Extent of inhibition decreased in the order: Inh(pAps)>Inh(pGlu)>Inh(pLys). The addition of a polypeptide into (2) caused the inhibition of precipitation and changed the morphology and polymorphic composition of the precipitate; only vaterite appeared at approximately c(pAsp)=3 ppm, c(pGlu)=6 ppm, or c(pLys)=7 ppm. This finding is explained as a consequence of kinetic constraints through the inhibition of calcite nucleation and stronger binding of acidic polypeptide by the calcite surfaces than by the vaterite surfaces. Laboratory precipitation studies using conditions that resemble those in living organism should be run at an initial supersaturation corresponding to the solubility of ACC as a limiting condition. 2009 Elsevier Inc. All rights reserved.

pH and its frequency distribution patterns of Acid Precipitation in Japan

International Nuclear Information System (INIS)

Kitamura, Moritsugu; Katou, Takunori; Sekiguchi, Kyoichi

1991-01-01

The pH data was collected at the 29 stations in Phase-I study of Acid Precipitation Survey over Japan by Japan Environment Agency in terms of frequency distribution patterns. This study was undertaken from April 1984 to March 1988, which was the first survey of acid precipitation over Japan with identical sampling procedures and subsequent chemical analyses. While the annual mean pH at each station ranged from 4.4 to 5.5, the monthly mean varied more widely, from 4.0 to 7.1. Its frequency distribution pattern was obtained for each station, and further grouped into four classes: class I; a mode at the rank of pH 4.5∼4.9, class II; bimodes above and below this pH region, class III; a mode at a higher pH region, class IV; a mode at a lower pH region. The bimodal pattern was suggestive of precipitation with and without incorporation of significant amounts of basic aerosol of anthropogenic origin during descent of rain droplet. The patterns of the stations were also classified on a basis of summer-winter difference into another four classes. Winter pH values were appreciably lower than summer pHs in western parts of Japan and on Japan Sea coast, we attribute the winter pH to probable contribution of acidic pollutants transported by strong winter monsoon from Eurasian Continent. At most stations in northern and eastern Japan, the pH was higher in winter months reflecting more incorporation of basic materials, e.g., NH 4 + and Ca 2+ . (author)

Oleic-acid-coated CoFe2O4 nanoparticles synthesized by co-precipitation and hydrothermal synthesis

International Nuclear Information System (INIS)

Gyergyek, Sašo; Drofenik, Miha; Makovec, Darko

2012-01-01

Highlights: ► Synthesis of oleic-acid-coated CoFe 2 O 4 nanoparticles from an aqueous solution. ► During the co-precipitation of Co 2+ /Fe 3+ single-phase spinel forms. ► During the co-precipitation of Co 2+ /Fe 2+ , feroxyhyte forms in addition to spinel. ► Oleic acid increases the spinel formation temperature and limits particle growth. ► Colloidal suspensions of ferrimagnetic CoFe 2 O 4 were prepared. - Abstract: Oleic-acid-coated CoFe 2 O 4 nanoparticles were synthesized by co-precipitation and hydrothermal synthesis. The coprecipitation of the nanoparticles was achieved by the rapid addition of a strong base to an aqueous solution of cations in the presence of the oleic acid surfactant, or without this additive. The nanoparticles were also synthesized by a hydrothermal treatment of suspensions of the precipitates, coprecipitated at room temperature in the presence of the oleic acid, or without it. The influence of the synthesis conditions, such as the valence state of the iron cation in the starting aqueous solution, the temperature of the treatment and the presence of oleic acid, on the particles size was systematically studied. X-ray powder diffractometry (XRD) and transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDS) revealed that, although spinel forms at room temperature, a substantial amount of Co was incorporated within the secondary, feroxyhyte-like phase when the iron cation was in the 2+ state. In contrast, when iron was in the 3+ state, the spinel forms at elevated temperatures of approximately 60 °C. The presence of the oleic acid further increased the formation temperature for the stoichiometric spinel. Moreover, the oleic acid impeded the particles’ growth and enabled the preparation of colloidal suspensions of the nanoparticles in non-polar organic solvents. The nanoparticles’ size was successfully controlled by the temperature of the synthesis in the region where superparamagnetism

Activities and results of the terrestrial effects program: acid precipitation in Ontario study (Apios)

Energy Technology Data Exchange (ETDEWEB)

Linzon, S N

1986-11-01

Studies on the terrestrial effects of acidic precipitation in Ontario involve determining the effects on soils, crops, forests, lichens, mosses and biogeochemical systems. In the soils program, a baseline study was started in 1980 to establish a reliable and uniform data base for soils across the province, in order to identify future trends. Soil sensitivity criteria are being derived for mapping purposes. Starting in 1982, a complex, sophisticated mobile rain exclusion canopy system was constructed outdoors for controlled acid rain studies to determine the dose-response relationships of field crops. In response to numerous complaints a program was designed to determine the role that acidic precipitation is playing in the decline of sugar maple trees in Ontario. At 8 sites, tree conditions were noted, samples of foliage, bark, roots and soil were collected for chemical analysis, and increment cores and discs (from felled trees) were taken for radial growth patterns. Results from this study indicated that acidic precipitation was an additional stress to insect outbreaks and spring droughts. Intensive surveys have been conducted in selected areas in Ontario to identify the current viability and distribution of common denominator lichens and mosses. Biogeochemical studies are being conducted at four watersheds in Ontario. The different watersheds are located in progressively decreasing atmospheric deposition loadings from east to west across the province. The studies are attempting to document the role of contrasting terrestrial ecosystems in the process of lake acidification by atmospheric deposition. 9 references.

Phosphate recovery through struvite-family crystals precipitated in the presence of citric acid: mineralogical phase and morphology evaluation.

Science.gov (United States)

Perwitasari, D S; Edahwati, L; Sutiyono, S; Muryanto, S; Jamari, J; Bayuseno, A P

2017-11-01

Precipitation strategy of struvite-family crystals is presented in this paper to recover phosphate and potassium from a synthetic wastewater in the presence of citric acid at elevated temperature. The crystal-forming solutions were prepared from crystals of MgCl 2 and NH 4 H 2 PO 4 with a molar ratio of 1:1:1 for Mg +2 , [Formula: see text], and [Formula: see text], and the citric acid (C 6 H 8 O 7 ) was prepared (1.00 and 20.00 ppm) from citric acid crystals. The Rietveld analysis of X-ray powder diffraction pattern confirmed a mixed product of struvite, struvite-(K), and newberyite crystallized at 30°C in the absence of citric acid. In the presence of citric acid at 30° and 40°C, an abundance of struvite and struvite-(K) were observed. A minute impurity of sylvite and potassium peroxide was unexpectedly found in certain precipitates. The crystal solids have irregular flake-shaped morphology, as shown by scanning electron microscopy micrograph. All parameters (citric acid, temperature, pH, Mg/P, and N/P) were deliberately arranged to control struvite-family crystals precipitation.

Ochre precipitates and Acid Mine Drainage in a mine environment

Czech Academy of Sciences Publication Activity Database

Máša, B.; Pulišová, Petra; Bezdička, Petr; Michalková, E.; Šubrt, Jan

2012-01-01

Roč. 56, č. 1 (2012), s. 9-14 ISSN 0862-5468 R&D Projects: GA MŠk(CZ) MEB0810136 Grant - others:Ministry of Education of the Slovak Republic(SK) VEGA 1/0529/09 Institutional research plan: CEZ:AV0Z40320502 Keywords : ochre precipitate * Acid Mine Drainage (AMD) * X-ray diffraction analysis (XRD) * Scanning electron microscopy (SEM) * specific surface area and porosity Subject RIV: CA - Inorganic Chemistry Impact factor: 0.418, year: 2012

Conceptual design of a novel CO2 capture process based on precipitating amino acid solvents

NARCIS (Netherlands)

Sanchez Fernandez, E.; Heffernan, K.; Ham, L.V. van der; Linders, M.J.G.; Eggink, E.; Schrama, F.N.H.; Brilman, D.W.F.; Goetheer, E.L.V.; Vlugt, T.J.H.

2013-01-01

Amino acid salt based solvents can be used for CO2 removal from flue gas in a conventional absorption-thermal desorption process. Recently, new process concepts have been developed based on the precipitation of the amino acid zwitterion species during the absorption of CO2. In this work, a new

Nitric acid adduct formation during crystallization of barium and strontium nitrates and their co-precipitation from nitric acid media

International Nuclear Information System (INIS)

Mishina, N.E.; Zilberman, B.Ya.; Lumpov, A.A.; Koltsova, T.I.; Puzikov, E.A.; Ryabkov, D.V.

2015-01-01

The molar solubilities of Ba, Sr and Pb nitrates in nitric acid as a function of total nitrate concentration is presented and described by the mass action law, indicating on formation of the adducts with nitric acid. Precipitates of Ba(NO 3 ) 2 and Sr(NO 3 ) 2 crystallized from nitric acid were studied by ISP OES and IR spectroscopy. The data obtained confirmed formation of metastable adducts with nitric acid. IR and X-ray diffraction studies of the mixed salt systems indicated conversion of the mixed salts into (Ba,Sr)(NO 3 ) 2 solid solution of discrete structure in range of total nitrate ion concentration ∼6 mol/L. (author)

Comparison of Four Strong Acids on the Precipitation Potential of Gypsum in Brines During Distillation of Pretreated, Augmented Urine

Science.gov (United States)

Muirhead, Dean; Carrier, Christopher

2012-01-01

In this study, three different mineral acids were substituted for sulfuric acid (H2SO4) in the urine stabilizer solution to eliminate the excess of sulfate ions in pretreated urine and assess the impact on maximum water recovery to avoid precipitation of minerals during distillation. The study evaluated replacing 98% sulfuric acid with 85% phosphoric acid (H3PO4), 37% hydrochloric acid (HCl), or 70% nitric acid (HNO3). The effect of lowering the oxidizer concentration in the pretreatment formulation also was studied. This paper summarizes the test results, defines candidate formulations for further study, and specifies the injection masses required to stabilize urine and minimize the risk of mineral precipitation during distillation. In the first test with a brine ersatz acidified with different acids, the solubility of calcium in gypsum saturated solutions was measured. The solubility of gypsum was doubled in the brines acidified with the alternative acids compared to sulfuric acid. In a second series of tests, the alternative acid pretreatment concentrations were effective at preventing precipitation of gypsum and other minerals up to 85% water recovery from 95th-percentile pretreated, augmented urine. Based on test results, phosphoric acid is recommended as the safest alternative to sulfuric acid. It also is recommended that the injected mass concentration of chromium trioxide solution be reduced by 75% to minimize liquid resupply mass by about 50%, reduce toxicity of brines, and reduce the concentration of organic acids in distillate. The new stabilizer solution formulations and required doses to stabilize urine and prevent precipitation of minerals up to 85% water recovery are given. The formulations in this study were tested on a limited number of artificially augmented urine batches collected from employees at the Johnson Space Center (JSC). This study successfully demonstrated that the desired physical and chemical stability of pretreated urine and brines

Calcium in milk products precipitates intestinal fatty acids and secondary bile acids and thus inhibits colonic cytotoxicity in humans

NARCIS (Netherlands)

Govers, MJAP; Termont, DSML; Lapre, JA; Kleibeuker, JH; Vonk, RJ; VanderMeer, R

1996-01-01

Dietary calcium may reduce the risk of colon cancer, probably by precipitating cytotoxic surfactants, such as secondary bile acids, in the colonic lumen. We previously showed that milk mineral, an important source of calcium, decreases metabolic risk factors and colonic proliferation in rats, We non

Study of lithium extraction from brine water, Bledug Kuwu, Indonesia by the precipitation series of oxalic acid and carbonate sodium

Science.gov (United States)

Sulistiyono, Eko; Lalasari, Latifa Hanum; Mayangsari, W.; Prasetyo, A. B.

2018-05-01

Lithium is one of the key elements in the development of batteries for electric car applications. Currently, the resources of the world's lithium are derived from brine water and lithium mineral based on spodumene rock. Indonesia which is located in the area of the ring of fire, has potential brine water resources in some area, such as brine water from Bledug Kuwu, Central Java that used in this research. The purposes of this research are to characterize brine water, Bledug Kuwu and to investigate the influence of chemical solvents on Li, Na, K, Ca, Mg, Al, B ion precipitation from brine water. This research was done with 2 times the process of chemical precipitation that runs series as follows: 5 liters of brine water were chemically precipitated using 400 ml of 12.43 N oxalic acid and followed by chemical precipitation using 400 mL of 7.07 N sodium carbonate solutions. Evaporation and filtration processes were also done twice in an effort to separate white precipitate and filtrate. The filtrate was analyzed by ICP-OES and white precipitates (salts) were analyzed by SEM, XRD, and XRF. The result shows that oxalate precipitation process extracted 32.24% Al, 23.42% B, 22.43% Ca, 14.26% Fe, 3.21 % K, 9.86% Na and 14.26% Li, the following process by carbonate precipitation process extracted 98.86% Mg, 73% Ca, 22.53% Li, 82.04% Al, 14.38% B, 12.50% K, 2.27% Na. There is 63.21% lithium is not extracted from the series process. The SEM analysis shows that the structure of granules on the precipitated salts by oxalic acid form gentle cubic-shaped solid. In the other hand, oxalate precipitation followed by sodium carbonate has various particle sizes and the shape of crystals is fragments, prism and cube look like magnesium carbonate, calcium chloride, and calcite's crystal respectively. This is in accordance with XRD analysis that phases of whewellite (CaC2O4.H2O), disodium oxalate (Na2C2O4), magnesite (MgCO3), calcium lithium aluminum (Al1.19 Ca1Li0.81), dolomite (CaCO3

Sustained release of nucleic acids from polymeric nanoparticles using microemulsion precipitation in supercritical carbon dioxide.

Science.gov (United States)

Ge, Jun; Jacobson, Gunilla B; Lobovkina, Tatsiana; Holmberg, Krister; Zare, Richard N

2010-12-21

A general approach for producing biodegradable nanoparticles for sustained nucleic acid release is presented. The nanoparticles are produced by precipitating a water-in-oil microemulsion in supercritical CO(2). The microemulsion consists of a transfer RNA aqueous solution (water phase), dichloromethane containing poly(l-lactic acid)-poly(ethylene glycol) (oil phase), the surfactant n-octyl β-D-glucopyranoside, and the cosurfactant n-butanol.

Acid deposition: State of science and technology. Summary report of the U.S. National Acid Precipitation Assessment Program

International Nuclear Information System (INIS)

Irving, P.M.; Smith, E.

1991-09-01

The twenty-seven State-of-Science and State-of-Technology (SOS/T) Reports, published in 1990 as the definitive scientific and technical synthesis of information obtained during the first decade of the U.S. national Acid Precipitation Assessment Program (NAPAP), are summarized in the document. In most cases, these summaries were the final chapter of the complete SOS/T Report

The production of rare earth elements group via tributyl phosphate extraction and precipitation stripping using oxalic acid

Directory of Open Access Journals (Sweden)

Esmaeil Jorjani

2016-11-01

Full Text Available In this study, solvent extraction and precipitation stripping were used to produce rare earth elements (REEs. Tributyl phosphate (TBP was used to extract yttrium, lanthanum, cerium, and neodymium from an aqueous solution produced by nitric acid leaching of apatite concentrate. In the extraction stage, the effects of TBP concentration, pH, contact time, temperature, and phase ratio were investigated. The results show that about 95%, 90%, 87% and 80% of neodymium, cerium, lanthanum, and yttrium, respectively, can be extracted in optimum conditions of extraction. Hot, deionized water was used to scrub the impurities from the loaded organic phase. The results showed that three stages of scrubbing with a phase ratio (Va/Vo of five removed about 80%, 30%, 27%, and 15% of Ca, Mg, Fe, and P, respectively, from loaded TBP, while less than 9% of total REEs was lost. The effects on precipitation stripping of oxalic acid concentration, contact time, and phase ratio were investigated. The results showed that precipitation stripping is a viable alternative to traditional acid stripping in the REEs production process. Mixed REEs oxide with an assay of about 90% can be achieved as a final product.

Removal of chromophore in enzymatic hydrolysis by acid precipitation to improve the quality of xylo-oligosaccharides from corn stalk.

Science.gov (United States)

Wang, Yue-Hai; Zhang, Jie; Qu, Yong-Shui; Li, Hong-Qiang

2018-02-01

As the most representative functional sugar, the application areas and market demands of xylo-oligosaccharides (XOS) have been expanding year by year. Owing to the complex structure of corn stalk (CS), XOS obtained from CS are accompanied by problems such as low purity and high color value, which degrade the product. To improve the quality of XOS from CS, the enzymatic hydrolysis was precipitated by acid; then, the ethanol elution concentration was systematically investigated after optimizing the adsorption conditions. The results showed that the purity of XOS was increased to 87.28% from 67.31%, and the color value was decreased to 1050 from 4682 when the acid precipitation pH was 2. On the basis of acid precipitation, if the corresponding optimal conditions of XOS adsorption and elution were used, the highest purity of XOS was 97.87% obtained, with the lowest color value, 780, which reached the standard of the commercial XOS. Copyright © 2017. Published by Elsevier Ltd.

Application of a precipitation method for uranium recovery from Abu-Zaabal phosphoric acid plant, egypt

International Nuclear Information System (INIS)

El-Hazek, N.M.T.; Hussein, E.M.

1997-01-01

Current industrial recovery of uranium from 30% phosphoric acid-produced by the dihydrate process-is based on solvent extraction method. Uranium recovery from concentrated phosphoric acid (45-52% P 2 O 5 ) produced by evaporation of the 30% acid or directly produced by the hemihydrate process, by solvent extraction is difficult to apply in practice. In addition to possible contamination of the acid by the organic solvents and/or their deterioration. This paper investigates the possibility of applying a precipitation method (Weterings and Janssen, 1985) for uranium recovery from both low (28% P 2 O 2 ) and high (48% P 2 O 5 ) concentration phosphoric acids produced by abu-Zaabal phosphoric acid plant (abu-Zaabal fertilizers and chemicals Co., Egypt). The 28% acid produced by H 2 SO 4 dihydrate method and the 48% acid produced by evaporation of the 28% acid

Microscopic evaluation of trace metals in cloud droplets in an acid precipitation region.

Science.gov (United States)

Li, Weijun; Wang, Yan; Collett, Jeffrey L; Chen, Jianmin; Zhang, Xiaoye; Wang, Zifa; Wang, Wenxing

2013-05-07

Mass concentrations of soluble trace metals and size, number, and mixing properties of nanometal particles in clouds determine their toxicity to ecosystems. Cloud water was found to be acidic, with a pH of 3.52, at Mt. Lu (elevation 1,165 m) in an acid precipitation region in South China. A combination of Inductively Coupled Plasma Mass Spectrometry (ICPMS) and Transmission Electron Microscopy (TEM) for the first time demonstrates that the soluble metal concentrations and solid metal particle number are surprisingly high in acid clouds at Mt. Lu, where daily concentrations of SO2, NO2, and PM10 are 18 μg m(-3), 7 μg m(-3), and 22 μg m(-3). The soluble metals in cloudwater with the highest concentrations were zinc (Zn, 200 μg L(-1)), iron (Fe, 88 μg L(-1)), and lead (Pb, 77 μg L(-1)). TEM reveals that 76% of cloud residues include metal particles that range from 50 nm to 1 μm diameter with a median diameter of 250 nm. Four major metal-associated particle types are Pb-rich (35%), fly ash (27%), Fe-rich (23%), and Zn-rich (15%). Elemental mapping shows that minor soluble metals are distributed within sulfates of cloud residues. Emissions of fine metal particles from large, nonferrous industries and coal-fired power plants with tall stacks were transported upward to this high elevation. Our results suggest that the abundant trace metals in clouds aggravate the impacts of acid clouds or associated precipitation on the ecosystem and human health.

Development and Preliminary Assessment of Hemoperfusion Cartridge with Tannic Acid for Toxic Proteins' Precipitation: An In Vitro Model

Directory of Open Access Journals (Sweden)

Valquíria Miwa Hanai Yoshida

2016-09-01

Full Text Available Charcoal hemoperfusion (CHP is one of the extracorporeal removal techniques that are used to remove toxins from the body. CHP generally is considered the preferred method for extracorporeal extraction of several toxins—toxins that are adsorbed by activated charcoal. Assessments of the tannic acid's protective effects on ophidian poisoning are associated with the toxic proteins' precipitation by tannic acid. The challenge in treating a snakebite lies in removing the injected poison with minimal damage to blood constituent proteins. An alternative is CHP, and this investigation proposed to develop a column for hemoperfuser cartridge, combining charcoal granules trapped between layers of polymeric material conjugated to tannic acid, using an in vitro model scaled to the Wistar rat, which can be tested in an animal model. The cartridge was evaluated using the 22 full factorial design, in duplicate, as a method to study the effects of granulated-charcoal size and tannic acid concentration on the hematologic profile (platelet and leukocyte counts and biochemical profile (total serum protein and albumin dosages of sheep blood. The results demonstrate that charcoal in hemoperfuser cartridge: (1 decreases the serum in sheep blood volume, as consequence, (2 increases the serum proteins' concentration, and (iii exerts slight influence on albumin. The inclusion of tannic acid in hemoperfuser column precipitates some of serum proteins and albumin, decreasing their concentrations in the plasma serum. In conclusion, based on these effects we can suggest the use of 0.02 g tannic acid concentration and 8–20 mesh granulated charcoal in hemoperfuser cartridge for precipitating toxic proteins from snake venoms.

Design of Test Facility to Evaluate Boric Acid Precipitation Following a LOCA

Energy Technology Data Exchange (ETDEWEB)

Suh, Jeong-Kwan; Song, Yong-Jae [KHNP CRI, Daejeon (Korea, Republic of)

2016-10-15

The U.S.NRC has identified a concern that debris associated with generic safety issue (GSI) - 191 may affect the potential precipitation of boric acid due to one or more of the following phenomena: - Reducing mass transport (i.e. mixing) between the core and the lower plenum (should debris accumulate at the core inlet) - Reduced lower plenum volume (should debris settle in the lower plenum), and, - Increased potential for boric acid precipitation (BAP) in the core (should debris accumulate in suspension in the core) To address these BAP issues, KHNP is planning to conduct validation tests by constructing a BAP test facility. This paper describes the design of test facility to evaluate BAP following a LOCA. The design of BAP test facility has been developed by KHNP. To design the test facility, test requirements and success criteria were established, and scaling analysis of power-to-volume method, Ishii-Kataoka method, and hierarchical two-tiered method were investigated. The test section is composed of two fuel assemblies with half of full of prototypic FA height. All the fuel rods are heated by the electric power supplier. The BAP tests in the presence of debris, buffering agents, and boron will be performed following the test matrix.

Biogenic precipitation of manganese oxides and enrichment of heavy metals at acidic soil pH

Science.gov (United States)

Mayanna, Sathish; Peacock, Caroline L.; Schäffner, Franziska; Grawunder, Anja; Merten, Dirk; Kothe, Erika; Büchel, Georg

2014-05-01

The precipitation of biogenic Mn oxides at acidic pH is rarely reported and poorly understood, compared to biogenic Mn oxide precipitation at near neutral conditions. Here we identified and investigated the precipitation of biogenic Mn oxides in acidic soil, and studied their role in the retention of heavy metals, at the former uranium mining site of Ronneburg, Germany. The site is characterized by acidic pH, low carbon content and high heavy metal loads including rare earth elements. Specifically, the Mn oxides were present in layers identified by detailed soil profiling and within these layers pH varied from 4.7 to 5.1, Eh varied from 640 to 660 mV and there were enriched total metal contents for Ba, Ni, Co, Cd and Zn in addition to high Mn levels. Using electron microprobe analysis, synchrotron X-ray diffraction and X-ray absorption spectroscopy, we identified poorly crystalline birnessite (δ-MnO2) as the dominant Mn oxide in the Mn layers, present as coatings covering and cementing quartz grains. With geochemical modelling we found that the environmental conditions at the site were not favourable for chemical oxidation of Mn(II), and thus we performed 16S rDNA sequencing to isolate the bacterial strains present in the Mn layers. Bacterial phyla present in the Mn layers belonged to Firmicutes, Actinobacteria and Proteobacteria, and from these phyla we isolated six strains of Mn(II) oxidizing bacteria and confirmed their ability to oxidise Mn(II) in the laboratory. The biogenic Mn oxide layers act as a sink for metals and the bioavailability of these metals was much lower in the Mn layers than in adjacent layers, reflecting their preferential sorption to the biogenic Mn oxide. In this presentation we will report our findings, concluding that the formation of natural biogenic poorly crystalline birnessite can occur at acidic pH, resulting in the formation of a biogeochemical barrier which, in turn, can control the mobility and bioavailability of heavy metals in

CONCENTRATION OF Pu USING AN IODATE PRECIPITATE

Science.gov (United States)

Fries, B.A.

1960-02-23

A method is given for separating plutonium from lanthanum in a lanthanum fluoride carrier precipitation process for the recovery of plutonium values from an aqueous solution. The carrier precipitation process includes the steps of forming a lanthanum fluoride precipi- . tate, thereby carrying plutonium out of solution, metathesizing the fluoride precipitate to a hydroxide precipitate, and then dissolving the hydroxide precipitate in nitric acid. In accordance with the invention, the nitric acid solution, which contains plutonium and lanthanum, is made 0.05 to 0.15 molar in potassium iodate. thereby precipitating plutonium as plutonous iodate and the plutonous iodate is separated from the lanthanum- containing supernatant solution.

Economic valuation of acidic deposition damages: Preliminary results from the 1985 NAPAP [National Acid Precipitation Assessment Program] damage assessment

International Nuclear Information System (INIS)

Callaway, J.M.; Darwin, R.F.; Nesse, R.J.

1985-01-01

This paper identifies methods used to evaluate the economic damages of acid deposition in the 1985 Damage Assessment being coordinated by the National Acid Precipitation Program. It also presents the preliminary estimates of economic damages for the Assessment. Economic damages are estimated for four effect areas: commercial agriculture and forests, recreational fishing and selected types of materials. In all but the last area, methods are used which incorporate the behavioral responses of individuals and firms or simulated physical damages to resources at risk. The preliminary nature of the estimated damages in each area is emphasized. Over all, the damage estimates should be interpreted with caution. 44 refs., 6 figs., 5 tabs

Continuous precipitation process of plutonium salts; Procede continu de precipitation des sels de plutonium

Energy Technology Data Exchange (ETDEWEB)

Richard, P [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1967-03-01

This work concerns the continuous precipitation process of plutonium oxalate. Investigations about the solubility of different valence states in nitric-oxalic and in nitric-sulfuric-oxalic medium lead to select the precipitation process of tetravalent plutonium oxalate. Settling velocity and granulometry of tetravalent oxalate plutonium have been studied with variation of several precipitation parameters such as: temperature, acidity, excess of oxalic acid and aging time. Then are given test results of some laboratory continuous apparatus. Conditions of operation with adopted tubular apparatus are defined in conclusion. A flow-sheet is given for a process at industrial scale. (author) [French] Cette etude porte sur la precipitation continue de l'oxalate de plutonium. L'etude de la solubilite des differentes valences du plutonium dans des milieux acides nitrique-oxalique, puis nitrique-sulfurique-oxalique conduit a choisir la precipitation de l'oxalate de plutonium tetravalent. L'etude porte ensuite sur la sedimentation et la granulometrie de l'oxalate de Pu{sup 4+} obtenue en faisant varier differents parametres de la precipitation : la temperature, l'acidite, l'exces oxalique et le temps de murissement. La derniere partie traite des resultats obtenus avec plusieurs types d'appareils continus essayes au laboratoire. En conclusion sont donnees les conditions de marche de l'appareil tubulaire adopte, ainsi qu'une extrapolation a l'echelle industrielle sous forme d'un flow-sheet. (auteur)

Recovery of Vanadium from H2SO4-HF Acidic Leaching Solution of Black Shale by Solvent Extraction and Precipitation

Directory of Open Access Journals (Sweden)

Xingbin Li

2016-03-01

Full Text Available The recovery of vanadium from sulfuric and hydrofluoric mixed acid solutions generated by the direct leaching of black shale was investigated using solvent extraction and precipitation methods. The process consisted of reduction, solvent extraction, and stripping, followed by precipitation and calcination to yield vanadium pentoxide. The influence of various operating parameters on the extraction and recovery of vanadium was studied. Vanadium (IV was selectively extracted using a mixture of 10% (v/v di(2-ethylhexylphosphoric acid and 5% (v/v tri-n-butylphosphate in sulfonated kerosene. Using six extraction and five stripping stages, the extraction efficiency for vanadium was 96.7% and the stripping efficiency was 99.7%. V2O5 with a purity of 99.52% was obtained by oxidation of the loaded strip solution and precipitation of ammonium polyvanadate at pH 1.8 to 2.2, followed by calcination of the dried precipitate at 550 °C for 2 h. It was concluded that the combination of solvent extraction and precipitation is an efficient method for the recovery of vanadium from a multi-element leach solution generated from black shale.

STRONTIUM PRECIPITATION

Science.gov (United States)

McKenzie, T.R.

1960-09-13

A process is given for improving the precipitation of strontium from an aqueous phosphoric-acid-containing solution with nickel or cobalt ferrocyanide by simultaneously precipitating strontium or calcium phosphate. This is accomplished by adding to the ferrocyanide-containing solution calcium or strontium nitrate in a quantity to yield a concentration of from 0.004 to 0.03 and adjusting the pH of the solution to a value of above 8.

Precipitation of humic acid with divalent ions

DEFF Research Database (Denmark)

Andersen, Niels Peder Raj; Mikkelsen, Lene Haugaard; Keiding, Kristian

2001-01-01

and Ba2+. The phase diagram model can not account for the observed precipitation in region III and However, in region IV the HA appears to posses colloidal properties, which is supported by precipitation taking place at a constant zeta-potential -21mV with the same amount of added barium ion regardless...

Acid Rain Examination and Chemical Composition of Atmospheric Precipitation in Tehran, Iran

Directory of Open Access Journals (Sweden)

Mohsen Saeedi

2012-01-01

Full Text Available Air pollution is one of the most important environmental problems in metropolitan cities like Tehran. Rain and snow, as natural events, may dissolve and absorb contaminants of the air and direct them onto the land or surface waters which become polluted. In the present study, precipitation samples were collected from an urbanized area of Tehran. They were analyzed for NO3-, PO43-, SO42-, pH, turbidity, Electrical Conductivity (EC, Cu, Fe, Zn, Pb, Ni, Cr, and Al. We demonstrate that snow samples were often more polluted and had lower pH than those from the rain, possibly as an effect of adsorption capability of snow flakes. Volume weighted average concentrations were calculated and compared with some other studies. Results revealed that Tehran's precipitations are much more polluted than those reported from other metropolitan cities. Cluster analysis revealed that studied parameters such as metals and acidity originated from the same sources, such as fuel combustion in residential and transportation sectors of Tehran.

TCA precipitation.

Science.gov (United States)

Koontz, Laura

2014-01-01

Trichloroacetic acid (TCA) precipitation of proteins is commonly used to concentrate protein samples or remove contaminants, including salts and detergents, prior to downstream applications such as SDS-PAGE or 2D-gels. TCA precipitation denatures the protein, so it should not be used if the protein must remain in its folded state (e.g., if you want to measure a biochemical activity of the protein). © 2014 Elsevier Inc. All rights reserved.

Inhibition of calcium phosphate precipitation under environmentally-relevant conditions

International Nuclear Information System (INIS)

Cao Xinde; Harris, Willie G.; Josan, Manohardeep S.; Nair, Vimala D.

2007-01-01

Precipitation of Ca phosphates plays an important role in controlling P activity and availability in environmental systems. The purpose of this study was to determine inhibitory effects on Ca phosphate precipitation by Mg 2+ , SO 4 2- , CO 3 2- , humic acid, oxalic acid, biogenic Si, and Si-rich soil clay commonly found in soils, sediments, and waste streams. Precipitation rates were determined by measuring decrease of P concentration in solutions during the first 60 min; and precipitated solid phases identified using X-ray diffraction and electron microscopy. Poorly-crystalline hydroxyapatite (HAP: Ca 5 (PO 4 ) 3 OH) formed in control solutions over the experiment period of 24 h, following a second-order dependence on P concentration. Humic acid and Mg 2+ significantly inhibited formation of HAP, allowing formation of a more soluble amorphous Ca phosphate phase (ACP), and thus reducing the precipitation rate constants by 94-96%. Inhibition caused by Mg 2+ results from its incorporation into Ca phosphate precipitates, preventing formation of a well-crystalline phase. Humic acid likely suppressed Ca phosphate precipitation by adsorbing onto the newly-formed nuclei. Presence of oxalic acid resulted in almost complete inhibition of HAP precipitation due to preemptive Ca-oxalate formation. Carbonate substituted for phosphate, decreasing the crystallinity of HAP and thus reducing precipitation rate constant by 44%. Sulfate and Si-rich solids had less impact on formation of HAP; while they reduced precipitation in the early stage, they did not differ from the control after 24 h. Results indicate that components (e.g., Mg 2+ , humic acid) producing relatively soluble ACP are more likely to reduce P stability and precipitation rate of Ca phosphate in soils and sediments than are components (e.g., SO 4 2- , Si) that have less effect on the crystallinity

Detrital processing in streams exposed to acidic precipitation in the Central Appalachian Mountains

International Nuclear Information System (INIS)

Meegan, S.K.; Perry, S.A.; Perry, W.B.

1996-01-01

Continuing high rates of acidic deposition in the eastern United States may lead to long-term effects on stream communities, because sensitive catchments are continuing to lose anions and cations. A two-year study of the effects of pH and associated water chemistry variables on detrital processing in three streams with different bedrock geology in the Monongahela National Forest, West Virginia were investigated. Leaf pack processing rates and macroinvertebrate colonization and microbial biomass (ATP concentration) on the packs in the three stream were compared. It was found that macroinvertebrate and microbial communities differed both among streams that differed in their capacity to buffer the effects of acidic precipitation and among years in the same stream; these differences in biotic communities were not large enough to affect rates of leaf processing between the two years of the study, but they did significantly affect processing rates between acidic and circumneutral streams

Gas Antisolvent Approach for the Precipitation of α -Methoxyphenylacetic Acid – ( R -1-Cyclohexylethylamine Diateromeric Salt

Directory of Open Access Journals (Sweden)

A. Zodge

2017-10-01

Full Text Available One of the major drawbacks of diastereomeric salt precipitation based enantioseparation is the time and solvent requirement of crystallization. In the gas antisolvent (GAS approach, supercritical carbon dioxide is applied as an antisolvent, and the precipitation takes place in a couple of minutes. By setting the process parameters diastereomeric excess, yields, and selectivity can be controlled. Applicability of the process is demonstrated on the resolution of racemic 2-methoxyphenylacetic acid with enantiopure (R-(−-1-cyclohexylethylamine. Diastereomeric excess values over 55 % along with 80 % yields were achieved at optimal conditions in a single step.

PRECIPITATION OF PROTACTINIUM

Science.gov (United States)

Moore, R.L.

1958-07-15

An lmprovement in the separation of protactinium from aqueous nitric acid solutions is described. 1t covers the use of lead dioxide and tin dioxide as carrier precipitates for the protactinium. In carrying out the process, divalent lead or divalent tin is addcd to the solution and oxidized, causing formation of a carrier precipitate of lead dioxide or stannic oxide, respectively.

IMPROVED PROCESS OF PLUTONIUM CARRIER PRECIPITATION

Science.gov (United States)

Faris, B.F.

1959-06-30

This patent relates to an improvement in the bismuth phosphate process for separating and recovering plutonium from neutron irradiated uranium, resulting in improved decontamination even without the use of scavenging precipitates in the by-product precipitation step and subsequently more complete recovery of the plutonium in the product precipitation step. This improvement is achieved by addition of fluomolybdic acid, or a water soluble fluomolybdate, such as the ammonium, sodium, or potassium salt thereof, to the aqueous nitric acid solution containing tetravalent plutonium ions and contaminating fission products, so as to establish a fluomolybdate ion concentration of about 0.05 M. The solution is then treated to form the bismuth phosphate plutonium carrying precipitate.

National Acid Precipitation Assessment Program Report to Congress: An Integrated Assessment

Energy Technology Data Exchange (ETDEWEB)

Uhart, M.; et al,

2005-08-01

Under Title IX of the 1990 Clean Air Act Amendments, Congress reauthorized the National Acid Precipitation Assessment Program (NAPAP) to continue coordinating acid rain research and monitoring, as it had done during the previous decade, and to provide Congress with periodic reports. In particular, Congress asked NAPAP to assess all available data and information to answer two questions: (1) What are the costs, benefits, and effectiveness of Title IV? This question addresses the costs and economic impacts of complying with the Acid Rain Program as well as benefit analyses associated with the various human health and welfare effects, including reduced visibility, damages to materials and cultural resources, and effects on ecosystems. (2) What reductions in deposition rates are needed to prevent adverse ecological effects? This complex questions addresses ecological systems and the deposition levels at which they experience harmful effects. The results of the assessment of the effects of Title IV and of the relationship between acid deposition rates and ecological effects were to be reported to Congress quadrennially, beginning with the 1996 report to Congress. The objective of this Report is to address the two main questions posed by Congress and fully communicate the results of the assessment to decision-makers. Given the primary audience, most of this report is not written as a technical document, although information supporting the conclusions is provided along with references.

Parametric study on co-precipitation of U/Th in MOX fuel of AHWR

International Nuclear Information System (INIS)

Tiwari, S.K.; Swaroopa Lakshmi, Y.; Nath, Baidurjya; Setty, D.S.; Kalyana Krishnan, G.; Saibaba, N.

2015-01-01

During manufacturing of Mixed Oxide Fuel (MOX) pellets for Advance Heavy Water Reactor (AHWR-LEU), around 30% rejected MOX pellets are generated in every cycle. These rejected MOX pellets are dissolved in nitric acid for recovery of U/Th. The recovered U/Th is recycled for production of MOX pellets. MOX pellets of varying compositions are used in AHWR fuel. Dissolution of MOX pellets in nitric acid is a challenging task because of its low surface area and longer dissolution times. High normal nitric acid is used in order to increase rate of dissolution, which in turn results in generation of high free acidity solution which influences the precipitation characteristics of Uranium (VI) by oxalic acid. Oxalic acid precipitation helps in generation of nitric acid which can be used for dissolution there by effectively facilitating nil effluent generation. Precipitation by oxalic acid unlike ammonia has advantage of zero liquid effluent discharge by complete recycle of oxalate filtrate to dissolution section. In the present work, the effect of various parameters like free acidity, residence time, concentration of oxalic acid, initial concentration of uranium and thorium etc. on the precipitation of U(VI) and Th(IV) in nitrate media by oxalic acid was carried out. The precipitated powder was subjected to various morphological evaluations like particle size etc. Study of various parameters on the co-precipitation of uranium and thorium by oxalic acid was carried out. It was observed that complete precipitation (> 99.9%) of thorium as oxalate does not depend on free acidity range (1- 6 N). Excess oxalic acid is not required for complete precipitation of thorium oxalate. The precipitation of uranyl oxalate varies with initial free acidity of solution. Uranyl oxalate precipitation does not take place at and above 5 N of free acidity

Fractionation of equine antivenom using caprylic acid precipitation in combination with cationic ion-exchange chromatography.

Science.gov (United States)

Raweerith, Rutai; Ratanabanangkoon, Kavi

2003-11-01

A combined process of caprylic acid (CA) precipitation and ion-exchange chromatography on SP-Sepharose was studied as a means to fractionate pepsin-digested horse antivenom F(ab')(2) antibody. In the CA precipitation, the optimal concentration for fractionation of F(ab')(2) from pepsin-digested horse plasma was 2%, in which 89.61% of F(ab')(2) antibody activity was recovered in the supernatant with 1.5-fold purification. A significant amount of pepsin was not precipitated and remained active under these conditions. An analytical cation exchanger Protein-Pak SP 8HR HPLC column was tested to establish optimal conditions for the effective separation of IgG, albumin, pepsin and CA from the F(ab')(2) product. From these results, the supernatant from CA precipitation of pepsin-digested plasma was subjected to a SP-Sepharose column chromatography using a linear salt gradient. With stepwise elution, a peak containing F(ab')(2) antibody could be obtained by elution with 0.25 M NaCl. The total recovery of antibody was 65.56% with 2.91-fold purification, which was higher than that achieved by ammonium sulfate precipitation. This process simultaneously and effectively removed residual pepsin, high molecular weight aggregates and CA in the final F(ab')(2) product, and should be suitable for large-scale fractionation of therapeutic equine antivenoms.

Response of surface water chemistry to reduced levels of acid precipitation: Comparison of trends in two regions of New York, USA

Science.gov (United States)

Burns, Douglas A.; McHale, M.R.; Driscoll, C.T.; Roy, K.M.

2006-01-01

In light of recent reductions in sulphur (S) and nitrogen (N) emissions mandated by Title IV of the Clean Air Act Amendments of 1990, temporal trends and trend coherence in precipitation (1984-2001 and 1992-2001) and surface water chemistry (1992-2001) were determined in two of the most acid-sensitive regions of North America, i.e. the Catskill and Adirondack Mountains of New York. Precipitation chemistry data from six sites located near these regions showed decreasing sulphate (SO42-), nitrate (NO3-), and base cation (CB) concentrations and increasing pH during 1984-2001, but few significant trends during 1992-2001. Data from five Catskill streams and 12 Adirondack lakes showed decreasing trends in SO42- concentrations at all sites, and decreasing trends in NO3-, CB, and H+ concentrations and increasing trends in dissolved organic carbon at most sites. In contrast, acid-neutralizing capacity (ANC increased significantly at only about half the Adirondack lakes and in one of the Catskill streams. Flow correction prior to trend analysis did not change any trend directions and had little effect on SO42- trends, but it caused several significant non-flow-corrected trends in NO3- and ANC to become non-significant, suggesting that trend results for flow-sensitive constituents are affected by flow-related climate variation. SO42- concentrations showed high temporal coherence in precipitation, surface waters, and in precipitation-surface water comparisons, reflecting a strong link between S emissions, precipitation SO42- concentrations, and the processes that affect S cycling within these regions. NO3- and H+ concentrations and ANC generally showed weak coherence, especially in surface waters and in precipitation-surface water comparisons, indicating that variation in local-scale processes driven by factors such as climate are affecting trends in acid-base chemistry in these two regions. Copyright ?? 2005 John Wiley & Sons, Ltd.

Synthesis of aqueous suspensions of magnetic nanoparticles with the co-precipitation of iron ions in the presence of aspartic acid

Energy Technology Data Exchange (ETDEWEB)

Pušnik, Klementina; Goršak, Tanja [Department for Materials Synthesis, Jožef Stefan Institute, 1000 Ljubljana (Slovenia); Jožef Stefan International Postgraduate School, 1000 Ljubljana (Slovenia); Drofenik, Miha [Department for Materials Synthesis, Jožef Stefan Institute, 1000 Ljubljana (Slovenia); Faculty of Chemistry and Chemical Engineering, University of Maribor, 2000 Maribor (Slovenia); Makovec, Darko [Department for Materials Synthesis, Jožef Stefan Institute, 1000 Ljubljana (Slovenia); Jožef Stefan International Postgraduate School, 1000 Ljubljana (Slovenia)

2016-09-01

There is increasing demand for the production of large quantities of aqueous suspensions of magnetic iron-oxide nanoparticles. Amino acids are one possible type of inexpensive, nontoxic, and biocompatible molecules that can be used as the surfactants for the preparation of stable suspensions. This preparation can be conducted in a simple, one-step process based on the co-precipitation of Fe{sup 3+}/Fe{sup 2+} ions in the presence of the amino acid. However, the presence of this amino acid changes the mechanism of the magnetic nanoparticles' formation. In this investigation we analyzed the influence of aspartic amino acid (Asp) on the formation of magnetic iron-oxide nanoparticles during the co-precipitation. The process of the nanoparticles’ formation was followed using a combination of TEM, x-ray diffractometry, magnetic measurements, in-situ FT-IR spectroscopy, and chemical analysis, and compared with the formation of nanoparticles without the Asp. The Asp forms a coordination complex with the Fe{sup 3+} ions, which impedes the formation of the intermediate iron oxyhydroxide phase and suppresses the growth of the final magnetic iron-oxide nanoparticles. Slower reaction kinetics can lead to the formation of nonmagnetic secondary phases. The aspartic-acid-absorbed nanoparticles can be dispersed to form relatively concentrated aqueous suspensions displaying a good colloidal stability at an increased pH. - Highlights: • Co-precipitation of Fe{sup 3+}/Fe{sup 2+} ions in the presence of aspartic amino acid (Asp). • Through analysis of nanoparticle formation mechanism. • Presence of Asp changes the mechanism of the nanoparticles’ formation. • Asp forms a coordination complex with the Fe{sup 3+} ions. • Asp impedes the formation of iron oxyhydroxide phase and suppresses the growth of iron-oxide nanoparticles. • The aspartic-acid-absorbed nanoparticles form stable aqueous suspensions.

Synthesis of aqueous suspensions of magnetic nanoparticles with the co-precipitation of iron ions in the presence of aspartic acid

International Nuclear Information System (INIS)

Pušnik, Klementina; Goršak, Tanja; Drofenik, Miha; Makovec, Darko

2016-01-01

There is increasing demand for the production of large quantities of aqueous suspensions of magnetic iron-oxide nanoparticles. Amino acids are one possible type of inexpensive, nontoxic, and biocompatible molecules that can be used as the surfactants for the preparation of stable suspensions. This preparation can be conducted in a simple, one-step process based on the co-precipitation of Fe 3+ /Fe 2+ ions in the presence of the amino acid. However, the presence of this amino acid changes the mechanism of the magnetic nanoparticles' formation. In this investigation we analyzed the influence of aspartic amino acid (Asp) on the formation of magnetic iron-oxide nanoparticles during the co-precipitation. The process of the nanoparticles’ formation was followed using a combination of TEM, x-ray diffractometry, magnetic measurements, in-situ FT-IR spectroscopy, and chemical analysis, and compared with the formation of nanoparticles without the Asp. The Asp forms a coordination complex with the Fe 3+ ions, which impedes the formation of the intermediate iron oxyhydroxide phase and suppresses the growth of the final magnetic iron-oxide nanoparticles. Slower reaction kinetics can lead to the formation of nonmagnetic secondary phases. The aspartic-acid-absorbed nanoparticles can be dispersed to form relatively concentrated aqueous suspensions displaying a good colloidal stability at an increased pH. - Highlights: • Co-precipitation of Fe 3+ /Fe 2+ ions in the presence of aspartic amino acid (Asp). • Through analysis of nanoparticle formation mechanism. • Presence of Asp changes the mechanism of the nanoparticles’ formation. • Asp forms a coordination complex with the Fe 3+ ions. • Asp impedes the formation of iron oxyhydroxide phase and suppresses the growth of iron-oxide nanoparticles. • The aspartic-acid-absorbed nanoparticles form stable aqueous suspensions.

Continuous precipitation process of plutonium salts

International Nuclear Information System (INIS)

Richard, P.

1967-03-01

This work concerns the continuous precipitation process of plutonium oxalate. Investigations about the solubility of different valence states in nitric-oxalic and in nitric-sulfuric-oxalic medium lead to select the precipitation process of tetravalent plutonium oxalate. Settling velocity and granulometry of tetravalent oxalate plutonium have been studied with variation of several precipitation parameters such as: temperature, acidity, excess of oxalic acid and aging time. Then are given test results of some laboratory continuous apparatus. Conditions of operation with adopted tubular apparatus are defined in conclusion. A flow-sheet is given for a process at industrial scale. (author) [fr

Kinetic study of the precipitation of radioactive elements in the production process of phosphoric acid

International Nuclear Information System (INIS)

Ben Mahmoud, Souha

2009-01-01

In this engineering study we determined the activities of gamma emitting radionuclides belonging to the families of 238 U , 232 Th and 40K in phosphate, the acid derivatives and gypsum in Tunisian Chemical Group. The most important activities are those of 238 U and 226 Ra, which are located in the phosphate, gypsum and the precipitates formed in the pipes.

Removal of sulfamic acid from plutonium sulfamate--sulfamic acid solution

International Nuclear Information System (INIS)

Gray, L.W.

1978-10-01

Plutonium metal can be readily dissolved in aqueous solutions of sulfamic acid. When the plutonium sulfamate--sulfamic acid solutions are added to normal purex process streams, the sulfamate ion is oxidized by addition of sodium nitrite. This generates sodium sulfate which must be stored as radioactive waste. When recovery of ingrown 241 Am or storage of the dissolved plutonium must be considered, the sulfamate ion poses major and undesirable precipitation problems in the process streams. The present studies show that 40 to 80% of the sulfamate present in the dissolver solutions can be removed by precipitation as sulfamic acid by the addition of concentrated nitric acid. Addition of 64% nitric acid allows precipitation of 40 to 50% of the sulfamate; addition of 72% nitric acid allows precipitation of 50 to 60% of the sulfamate. If the solutions are chilled, additional sulfamic acid will precipitate. If the solutions are chilled to -10 0 C, about 70 to 80% of the orginal sulfamic acid in the dissolver will precipitate. A single, low-volume wash of the sulfamic acid crystals with concentrated nitric acid will decontaminate the crystals to a plutonium content of 5 dis/(min-gram)

Influence of commercial (Fluka) naphthenic acids on acid volatile sulfide (AVS) production and divalent metal precipitation.

Science.gov (United States)

McQueen, Andrew D; Kinley, Ciera M; Rodgers, John H; Friesen, Vanessa; Bergsveinson, Jordyn; Haakensen, Monique C

2016-12-01

Energy-derived waters containing naphthenic acids (NAs) are complex mixtures often comprising a suite of potentially problematic constituents (e.g. organics, metals, and metalloids) that need treatment prior to beneficial use, including release to receiving aquatic systems. It has previously been suggested that NAs can have biostatic or biocidal properties that could inhibit microbially driven processes (e.g. dissimilatory sulfate reduction) used to transfer or transform metals in passive treatment systems (i.e. constructed wetlands). The overall objective of this study was to measure the effects of a commercially available (Fluka) NA on sulfate-reducing bacteria (SRB), production of sulfides (as acid-volatile sulfides [AVS]), and precipitation of divalent metals (i.e. Cu, Ni, Zn). These endpoints were assessed following 21-d aqueous exposures of NAs using bench-scale reactors. After 21-days, AVS molar concentrations were not statistically different (pAVS production was sufficient in all NA treatments to achieve ∑SEM:AVS AVS) could be used to treat metals occurring in NAs affected waters. Copyright © 2016 Elsevier Inc. All rights reserved.

Separation and Precipitation of Nickel from Acidic Sulfate Leaching Solution of Molybdenum-Nickel Black Shale by Potassium Nickel Sulfate Hexahydrate Crystallization

Science.gov (United States)

Deng, Zhigan; Wei, Chang; Fan, Gang; Li, Xingbin; Li, Minting; Li, Cunxiong

2018-02-01

Nickel was separated and precipitated with potassium nickel sulfate hexahydrate [K2Ni(SO4)2·6H2O] from acidic sulfate solution, a leach solution from molybdenum-nickel black shale. The effects of the potassium sulfate (K2SO4) concentration, crystallization temperature, solution pH, and crystallization time on nickel(II) recovery and iron(III) precipitation were investigated, revealing that nickel and iron were separated effectively. The optimum parameters were K2SO4 concentration of 200 g/L, crystallization temperature of 10°C, solution pH of 0.5, and crystallization time of 24 h. Under these conditions, 97.6% nickel(II) was recovered as K2Ni(SO4)2·6H2O crystals while only 2.0% of the total iron(III) was precipitated. After recrystallization, 98.4% pure K2Ni(SO4)2·6H2O crystals were obtained in the solids. The mother liquor was purified by hydrolysis-precipitation followed by cooling, and more than 99.0% K2SO4 could be crystallized. A process flowsheet was developed to separate iron(III) and nickel(II) from acidic-sulfate solution.

Investigation of Neptunium Precipitator Cleanout Options

International Nuclear Information System (INIS)

Hill, B.C.

2003-01-01

Oxalate precipitation followed by filtration is used to prepare plutonium oxalate. Historically, plutonium oxalate has tended to accumulate in the precipitation tanks. These solids are periodically removed by flushing with concentrated (64 percent) nitric acid. The same precipitation tanks will now be used in the processing of neptunium. Literature values indicate that neptunium oxalate may not be as soluble as plutonium oxalate in nitric acid. Although a wide variety of options is available to improve neptunium oxalate solubility for precipitator flushing, most of these options are not practical for use. Many of these options require the use of incompatible or difficult to handle chemicals. Other options would require expensive equipment modifications or are likely to lead to product contamination. Based on review of literature and experimental results, the two best options for flushing the precipitator are (1) 64 percent nitric acid and (2) addition of sodium permanganate follow ed by sodium nitrite. Nitric acid is the easiest option to implement. It is already used in the facility and will not lead to product contamination. Experimental results indicate that neptunium oxalate can be dissolved in concentrated nitric acid (64 percent) at 60 degree C to a concentration of 2.6 to 5.6 grams of Np/liter after at least three hours of heating. A lower concentration (1.1 grams of Np/liter) was measured at 60 degree C after less than two hours of heating. These concentrations are acceptable for flushing if precipitator holdup is low (approximately 100-250 grams), but a second method is required for effective flushing if precipitator holdup is high (approximately 2 kilograms). The most effective method for obtaining higher neptunium concentrations is the use of sodium permanganate followed by the addition of sodium nitrite. There is concern that residual manganese from these flushes could impact product purity. Gas generation during permanganate addition is also a concern

Precipitation of plutonium oxalate from homogeneous solutions

International Nuclear Information System (INIS)

Rao, V.K.; Pius, I.C.; Subbarao, M.; Chinnusamy, A.; Natarajan, P.R.

1986-01-01

A method for the precipitation of plutonium(IV) oxalate from homogeneous solutions using diethyl oxalate is reported. The precipitate obtained is crystalline and easily filterable with yields in the range of 92-98% for precipitations involving a few mg to g quantities of plutonium. Decontamination factors for common impurities such as U(VI), Am(III) and Fe(III) were determined. TGA and chemical analysis of the compound indicate its composition as Pu(Csub(2)Osub(4))sub(2).6Hsub(2)O. Data are obtained on the solubility of the oxalate in nitric acid and in mixtures of nitric acid and oxalic acid of varying concentrations. Green PuOsub(2) obtained by calcination of the oxalate has specifications within the recommended values for trace foreign substances such as chlorine, fluorine, carbon and nitrogen. (author)

DISSOLUTION OF LANTHANUM FLUORIDE PRECIPITATES

Science.gov (United States)

Fries, B.A.

1959-11-10

A plutonium separatory ore concentration procedure involving the use of a fluoride type of carrier is presented. An improvement is given in the derivation step in the process for plutonium recovery by carrier precipitation of plutonium values from solution with a lanthanum fluoride carrier precipitate and subsequent derivation from the resulting plutonium bearing carrier precipitate of an aqueous acidic plutonium-containing solution. The carrier precipitate is contacted with a concentrated aqueous solution of potassium carbonate to effect dissolution therein of at least a part of the precipitate, including the plutonium values. Any remaining precipitate is separated from the resulting solution and dissolves in an aqueous solution containing at least 20% by weight of potassium carbonate. The reacting solutions are combined, and an alkali metal hydroxide added to a concentration of at least 2N to precipitate lanthanum hydroxide concomitantly carrying plutonium values.

Kinetics of cadmium hydroxide precipitation

International Nuclear Information System (INIS)

Patterson, J.W.; Marani, D.; Luo, B.; Swenson, P.

1987-01-01

This paper presents some preliminary results on the kinetics of Cd(OH)/sub 2/ precipitation, both in the absence and the presence of citric acid as an inhibiting agent. Batch and continuous stirred tank reactor (CSTR) precipitation studies are performed by mixing equal volumes of NaOH and Cd(NO/sub 3/)/sub 2/ solutions, in order to avoid localized supersaturation conditions. The rate of metal removal from the soluble phase is calculated from the mass balance for the CSTR precipitation tests. In addition, precipitation kinetics are studied in terms of nucleation and crystal growth rates, by means of a particle counter that allows a population balance analysis for the precipitation reactor at steady state conditions

Synthesis of aqueous suspensions of magnetic nanoparticles with the co-precipitation of iron ions in the presence of aspartic acid

Science.gov (United States)

Pušnik, Klementina; Goršak, Tanja; Drofenik, Miha; Makovec, Darko

2016-09-01

There is increasing demand for the production of large quantities of aqueous suspensions of magnetic iron-oxide nanoparticles. Amino acids are one possible type of inexpensive, nontoxic, and biocompatible molecules that can be used as the surfactants for the preparation of stable suspensions. This preparation can be conducted in a simple, one-step process based on the co-precipitation of Fe3+/Fe2+ ions in the presence of the amino acid. However, the presence of this amino acid changes the mechanism of the magnetic nanoparticles' formation. In this investigation we analyzed the influence of aspartic amino acid (Asp) on the formation of magnetic iron-oxide nanoparticles during the co-precipitation. The process of the nanoparticles' formation was followed using a combination of TEM, x-ray diffractometry, magnetic measurements, in-situ FT-IR spectroscopy, and chemical analysis, and compared with the formation of nanoparticles without the Asp. The Asp forms a coordination complex with the Fe3+ ions, which impedes the formation of the intermediate iron oxyhydroxide phase and suppresses the growth of the final magnetic iron-oxide nanoparticles. Slower reaction kinetics can lead to the formation of nonmagnetic secondary phases. The aspartic-acid-absorbed nanoparticles can be dispersed to form relatively concentrated aqueous suspensions displaying a good colloidal stability at an increased pH.

Seasonal factors controlling mineral precipitation in the acid mine drainage at Donghae coal mine, Korea

International Nuclear Information System (INIS)

Kim, J.J.; Kim, S.J.

2004-01-01

Monitoring over a 12 month period in the Sanae creek flow in acid mine drainage, Donghae coal mine area, demonstrates that the concentrations of dissolved metals and sulphate are highest during autumn when water flow in the creek is at its lowest. The highest pH values of the stream were measured in April and May, whereas the lowest pH was recorded in October. The Fe concentration of stream water rapidly decreased downstream due to the precipitation of Fe oxyhydroxide and/or oxyhydroxysulfate phases in the stream. Mineral precipitates in the creek in the Donghae mine area show various colours such as brownish yellow (Munsell colour 9.5 YR hues), reddish brown (Munsell colour 3.5 YR hues) and white depending on seasons and distance from the pollution source in the creek. Such phenomena are attributed to the variation in pH and chemical composition of stream water caused by seasonal factors. The measured pH ranges in stream water of the brownish yellow, white and reddish brown precipitates are pH 3.2-4.5, 4.5-6.0 and 5.3-6.9, respectively

Crosslinkers of Different Types in Precipitation Polymerization of Acrylic Acid

Directory of Open Access Journals (Sweden)

H. Eshaghi

2013-01-01

Full Text Available Crosslinked poly(acrylic acids were prepared using two types of crosslinker by precipitation polymerization method in a binary organic solvent. N,N’-methylenebisacrylamide (MBA and polyethylene glycol dimethacrylate (PEGDMA-330 were used as low-molecular weight and long-chain crosslinkers, respectively. The effect of various types of crosslinkers on polymer characteristics (i.e., gel content, equilibrium swelling, glass transition temperature, and rheological properties was investigated. Maximum amount of viscosity was obtained by using long-chain crosslinker. The Flory-Rehner equation and rubber elasticity theory were used to discuss the network structure of polymer. It was observed that, the glass transition temperature (Tg of the synthesized polymer containing PEGDMA-330 is higher than that of polymer containing MBA. Apparent and rotational viscosity were used to determine the optimal crosslinker type. In addition, the consistencycoefficient (m and flow behavior index (n parameter of Ostwald equation were investigated as well.

An Optimized Trichloroacetic Acid/Acetone Precipitation Method for Two-Dimensional Gel Electrophoresis Analysis of Qinchuan Cattle Longissimus Dorsi Muscle Containing High Proportion of Marbling.

Science.gov (United States)

Hao, Ruijie; Adoligbe, Camus; Jiang, Bijie; Zhao, Xianlin; Gui, Linsheng; Qu, Kaixing; Wu, Sen; Zan, Linsen

2015-01-01

Longissimus dorsi muscle (LD) proteomics provides a novel opportunity to reveal the molecular mechanism behind intramuscular fat deposition. Unfortunately, the vast amounts of lipids and nucleic acids in this tissue hampered LD proteomics analysis. Trichloroacetic acid (TCA)/acetone precipitation is a widely used method to remove contaminants from protein samples. However, the high speed centrifugation employed in this method produces hard precipitates, which restrict contaminant elimination and protein re-dissolution. To address the problem, the centrifugation precipitates were first grinded with a glass tissue grinder and then washed with 90% acetone (TCA/acetone-G-W) in the present study. According to our result, the treatment for solid precipitate facilitated non-protein contaminant removal and protein re-dissolution, ultimately improving two-dimensional gel electrophoresis (2-DE) analysis. Additionally, we also evaluated the effect of sample drying on 2-DE profile as well as protein yield. It was found that 30 min air-drying did not result in significant protein loss, but reduced horizontal streaking and smearing on 2-DE gel compared to 10 min. In summary, we developed an optimized TCA/acetone precipitation method for protein extraction of LD, in which the modifications improved the effectiveness of TCA/acetone method.

Organic influences on inorganic patterns of diffusion-controlled precipitation in gels

Science.gov (United States)

Barge, Laura M.; Nealson, Kenneth H.; Petruska, John

2010-06-01

The well-known AgNO 3/K 2CrO 4 reaction-diffusion system produces periodic bands of silver chromate precipitate in gelatin, but only randomly oriented crystals in agarose gel. We show that comparable bands can be produced in agarose gel by adding small amounts of simple organic acids (e.g., acetic acid, N-acetyl glycine, and N-acetyl alanine) that suppress crystal growth and promote formation of rounded particles of precipitate. These results indicate that α-carboxyl groups of amino acids or short peptides in gelatin under mildly acidic conditions can induce periodic band patterns in diffusion-controlled silver chromate precipitates.

A perspective of stepwise utilisation of Bayer red mud: Step two—Extracting and recovering Ti from Ti-enriched tailing with acid leaching and precipitate flotation

International Nuclear Information System (INIS)

Huang, Yanfang; Chai, Wencui; Han, Guihong; Wang, Wenjuan; Yang, Shuzhen; Liu, Jiongtian

2016-01-01

Highlights: • An integrated process for the stepwise disposal of red mud was proposed. • Extracting and recovering Ti from Ti-enriched tailing was the second step. • The factors influencing acid leaching and precipitate flotation were examined. • The extracting of metals in concentrated H 2 SO 4 was controlled by diffusion reactions. • [Hbet][Tf 2 N] was an effective precipitating reagent with its coordination mechanism. - Abstract: The extraction and recovery of Ti from Ti-enriched tailing with acid leaching and precipitate flotation, as one of the critical steps, was proposed for the stepwise utilization of red mud. The factors influencing acid leaching and precipitate flotation were examined by factorial design. The leaching thermodynamics, kinetics of Ti 4+ , Al 3+ and Fe 3+ , and the mechanism of selectively Fe 3+ removal using [Hbet][Tf 2 N] as precipitating reagent were discussed. The extracting of Ti 4+ , Al 3+ and Fe 3+ in concentrated H 2 SO 4 is controlled by diffusion reactions, depending mainly upon leaching time and temperature. The maximum extracting efficiency of Ti 4+ is approximately 92.3%, whereas Al 3+ and Fe 3+ leaching are respectively 75.8% and 84.2%. [Hbet][Tf 2 N], as a precipitating reagent, operates through a coordination mechanism in flotation. The pH value is the key factor influencing the flotation recovery of Ti 4+ , whereas the dosage of precipitating reagent is that for Al 3+ recovery. The maximum flotation recovery of Ti 4+ is 92.7%, whereas the maximum Al 3+ recovery is 93.5%. The total recovery rate for extracting and recovering titanium is 85.5%. The liquor with Ti 4+ of 15.5 g/L, Al 3+ of 30.4 g/L and Fe 3+ of 0.48 g/L was obtained for the following hydrolysis step in the integrated process for red mud utilisation.

Removal of palladium precipitate from a simulated high-level radioactive liquid waste by reduction by ascorbic acid

International Nuclear Information System (INIS)

Kim, Eung Ho; Yoo, Jae Hyung; Choi, Cheong Song

1998-01-01

A study of the selective removal of Palladium from a simulated solution of high-level radioactive liquid waste (HLLW) was carried out. The simulated solution contained 7 representative elements (Pd 2+ , Cs + , Sr 2+ , Fe 3+ , MoO 2 2+ , Ru 4+ , and Nd 3+ ) typical of HLLW, ascorbic acid was added to the solution at room temperature. Pd 2+ in the simulated solution was easily reduced to Pd metal by the ascorbic acid and then the metal precipitate could be removed from the solution, whereas other elements remained mainly in solution. When the resulting Pd metal was left in solution, it was reoxidized to Pb 2+ ion and redissolved in a nitric acid medium. The oxidation rate of Pd 2+ depended on the presence of a transition metal such as ferric ion, and was also in proportion to the concentration of nitric acid and in inverse proportion to the concentration of ascrobic acid. (orig.)

Behaviour of the pH adjustment, Ion exchange and concentrate precipitation stages in the acid leaching of uranium phosphate ores

International Nuclear Information System (INIS)

Estrada Aguilar, J.; Uriarte Hueda, A.

1962-01-01

The uranium recovery from acid leach solutions of uranium-phosphate ores has been studied. Relations have been found between the solution characteristics and the results obtained at different stages of the process. The following data can thus be predicted: solids to remove and uranium recovery in the pH adjustment stage, uranium capacity of the resin, more suitable eluating agent, elution velocity and uranium concentration in the eluate in the ion exchange stage, and composition of the concentrate produced by direct precipitation of the eluate in the concentrate precipitation stage. (Author) 8 refs

Application of citric acid in acid stimulation treatments

Energy Technology Data Exchange (ETDEWEB)

Alkhaldi, M.H.; Sarma, H.K. [Adelaide Univ., Adelaide (Australia); Nasr-el-Din, H.A. [Texas A and M Univ., College Station, TX (United States)

2009-07-01

A rotating disk apparatus was used to investigate mass transfer during the reaction of citric acid with calcite. The study evaluated the effects of initial acid concentrations, temperature, and disk rotational speed on the effective diffusion coefficient of citric acid. The diffusion coefficient was calculated at 25, 40, and 50 degrees C using various citric acid concentrations. The study indicated that the coefficient was a function of the interactions between calcium citrate precipitation and counter calcium ions. At high acid concentrations, the effects of calcium citrate precipitation and counter calcium ions were significant. The calculated citric acid diffusion coefficients were not comparable with measured effective diffusion coefficients using the rotating disk. At lower initial citric acid concentrations, the effects of both calcium citrate precipitation and counter calcium ions on citric acid diffusivity were minimal. It was concluded that temperature effects on the diffusion coefficient followed Arrhenius law. Activation energy was equal to 37.9 kJ/mol. 34 refs., 4 tabs., 13 figs.

Boronic Acid functionalized core-shell polymer nanoparticles prepared by distillation precipitation polymerization for glycopeptide enrichment.

Science.gov (United States)

Qu, Yanyan; Liu, Jianxi; Yang, Kaiguang; Liang, Zhen; Zhang, Lihua; Zhang, Yukui

2012-07-16

The boronic acid-functionalized core-shell polymer nanoparticles, poly(N,N-methylenebisacrylamide-co-methacrylic acid)@4-vinylphenylboronic acid (poly(MBA-co-MAA)@VPBA), were successfully synthesized for enriching glycosylated peptides. Such nanoparticles were composed of a hydrophilic polymer core prepared by distillation precipitation polymerization (DPP) and a boronic acid-functionalized shell designed for capturing glycopeptides. Owing to the relatively large amount of residual vinyl groups introduced by DPP on the core surface, the VPBA monomer was coated with high efficiency, working as the shell. Moreover, the overall polymerization route, especially the use of DPP, made the synthesis of nanoparticles facile and time-saving. With the poly(MBA-co-MAA)@VPBA nanoparticles, 18 glycopeptides from horseradish peroxidase (HRP) digest were captured and identified by MALDI-TOF mass spectrometric analysis, relative to eight glycopeptides enriched by using commercially available meta-aminophenylboronic acid agarose under the same conditions. When the concentration of the HRP digest was decreased to as low as 5 nmol, glycopeptides could still be selectively isolated by the prepared nanoparticles. Our results demonstrated that the synthetic poly(MBA-co-MAA)@VPBA nanoparticles might be a promising selective enrichment material for glycoproteome analysis. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A perspective of stepwise utilisation of Bayer red mud: Step two—Extracting and recovering Ti from Ti-enriched tailing with acid leaching and precipitate flotation

Energy Technology Data Exchange (ETDEWEB)

Huang, Yanfang; Chai, Wencui; Han, Guihong, E-mail: guihong-han@hotmail.com; Wang, Wenjuan; Yang, Shuzhen; Liu, Jiongtian

2016-04-15

Highlights: • An integrated process for the stepwise disposal of red mud was proposed. • Extracting and recovering Ti from Ti-enriched tailing was the second step. • The factors influencing acid leaching and precipitate flotation were examined. • The extracting of metals in concentrated H{sub 2}SO{sub 4} was controlled by diffusion reactions. • [Hbet][Tf{sub 2}N] was an effective precipitating reagent with its coordination mechanism. - Abstract: The extraction and recovery of Ti from Ti-enriched tailing with acid leaching and precipitate flotation, as one of the critical steps, was proposed for the stepwise utilization of red mud. The factors influencing acid leaching and precipitate flotation were examined by factorial design. The leaching thermodynamics, kinetics of Ti{sup 4+}, Al{sup 3+} and Fe{sup 3+}, and the mechanism of selectively Fe{sup 3+} removal using [Hbet][Tf{sub 2}N] as precipitating reagent were discussed. The extracting of Ti{sup 4+}, Al{sup 3+} and Fe{sup 3+} in concentrated H{sub 2}SO{sub 4} is controlled by diffusion reactions, depending mainly upon leaching time and temperature. The maximum extracting efficiency of Ti{sup 4+} is approximately 92.3%, whereas Al{sup 3+} and Fe{sup 3+} leaching are respectively 75.8% and 84.2%. [Hbet][Tf{sub 2}N], as a precipitating reagent, operates through a coordination mechanism in flotation. The pH value is the key factor influencing the flotation recovery of Ti{sup 4+}, whereas the dosage of precipitating reagent is that for Al{sup 3+} recovery. The maximum flotation recovery of Ti{sup 4+} is 92.7%, whereas the maximum Al{sup 3+} recovery is 93.5%. The total recovery rate for extracting and recovering titanium is 85.5%. The liquor with Ti{sup 4+} of 15.5 g/L, Al{sup 3+} of 30.4 g/L and Fe{sup 3+} of 0.48 g/L was obtained for the following hydrolysis step in the integrated process for red mud utilisation.

Antisolvent Precipitation for the Synthesis of Monodisperse Mesoporous Niobium Oxide Spheres as Highly Effective Solid Acid Catalysts

KAUST Repository

Li, Cheng Chao; Dou, Jian; Chen, Luwei; Lin, Jianyi; Zeng, Hua Chun

2012-01-01

We have developed a low-cost reaction protocol to synthesize mesoporous Nb 2O 5-based solid acid catalysts with external shape control. In the synthesis, monodisperse glycolated niobium oxide spheres (GNOS) were prepared by means of a simple antisolvent precipitation approach and subsequently converted to mesoporous niobium oxide spheres (MNOS) with a large surface area of 312m 2g -1 by means of the hydrothermal treatment. The antisolvent acetone used to obtain GNOS was recovered through distillation at high purity. The obtained mesoporous MNOS were functionalized further with sulfate anions at different temperatures or incorporated with tungstophosphoric acid to obtain recyclable solid acid catalysts. These MNOS-based catalysts showed excellent performance in a wide range of acid-catalyzed reactions, such as Friedel-Crafts alkylation, esterification, and hydrolysis of acetates. As they are monodisperse spheres with diameters in the submicrometer range, the catalysts can be easily separated and reused. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Antisolvent Precipitation for the Synthesis of Monodisperse Mesoporous Niobium Oxide Spheres as Highly Effective Solid Acid Catalysts

KAUST Repository

Li, Cheng Chao

2012-03-20

We have developed a low-cost reaction protocol to synthesize mesoporous Nb 2O 5-based solid acid catalysts with external shape control. In the synthesis, monodisperse glycolated niobium oxide spheres (GNOS) were prepared by means of a simple antisolvent precipitation approach and subsequently converted to mesoporous niobium oxide spheres (MNOS) with a large surface area of 312m 2g -1 by means of the hydrothermal treatment. The antisolvent acetone used to obtain GNOS was recovered through distillation at high purity. The obtained mesoporous MNOS were functionalized further with sulfate anions at different temperatures or incorporated with tungstophosphoric acid to obtain recyclable solid acid catalysts. These MNOS-based catalysts showed excellent performance in a wide range of acid-catalyzed reactions, such as Friedel-Crafts alkylation, esterification, and hydrolysis of acetates. As they are monodisperse spheres with diameters in the submicrometer range, the catalysts can be easily separated and reused. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influence of chemical composition of precipitation on migration of radioactive caesium in natural soils

International Nuclear Information System (INIS)

Thørring, H.; Skuterud, L.; Steinnes, E.

2014-01-01

The aim of the present work was to study the impact of the chemical composition of precipitation on radiocaesium mobility in natural soil. This was done through column studies. Three types of precipitation regimes were studied, representing a natural range found in Norway: Acidic precipitation (southernmost part of the country); precipitation rich in marine cations (highly oceanic coastal areas); and low concentrations of sea salts (slightly continental inland areas). After 50 weeks and a total precipitation supply of ∼10 000 L m −2 per column, results indicate that acidic precipitation increased the mobility of 134 Cs added during the experiment. However, depth distribution of already present Chernobyl fallout 137 Cs was not significantly affected by the chemical composition of precipitation. - Highlights: • Mobility of freshly added Cs-134 was higher in soil receiving acidic precipitation. • Depth penetration of Cs-134 was higher in soil profiles with a thicker humus layer. • Depth distribution of Chernobyl Cs-137 was not affected by precipitation type

Prediction and mastering of wine acidity and tartaric precipitations: the Mextar® software tool

Directory of Open Access Journals (Sweden)

Audrey Devatine

2002-06-01

The article describes the theoretical background upon which MEXTAR® has been developed and details the computation procedures associated to the simulation of the operations described above. Iterative processes are used to determine the various parameters enounced above. They aim in particular at the verification of the electroneutrality of the sample. However, at first electroneutrality is rarely verified because the wine chemical analytical determination is never exhaustive. Therefore, we introduce the concept of «vinic acid» to compensate the negative ion deficit of usual wine chemical analytical determination. This «vinic acid» is describe as a diacid with a fixed second dissociation constant (pK2 = 5 and a first dissociation constant determined automatically by MEXTAR®. This enables MEXTAR® to simulate accurately experimental tartaric precipitations for several samples. Thanks to the predicting capacity of MEXTAR®, the correlation between the total polyphenol content (IPT in red wines and the difficulty to stabilise high IPT wine with respect to tartaric salts is confirmed. Finally, malolactic fermentations are also well simulated. A validation of MEXTAR® for the acid addition or removal has yet to be done when reliable experimental data are available.

Study on uranium loss during 'Iron-Gypsum Cake' precipitation from acid leach liquor of Jaduguda ore using factorially designed experiments

International Nuclear Information System (INIS)

Das, Amrita; Yadav, Manoj; Chatterjee, Ankur; Singh, A.K.; Hubli, R.C.

2012-01-01

Acid leaching process for uranium recovery from ore often generates considerable amounts of impurities into the solution. It is a challenge to separate the non-valuable impurities as manageable and stable waste products for final disposal, without losing the valuable constituents. The main impurities that come with the leach liquor are iron and sulfate. Their removal is essential for meeting the iron requirement in leaching circuit and also for making the effluent suitable for recycle. Factorial design analysis was applied to study of process variables for precipitation of iron and sulphate from leach liquor with composition using CaO as precipitation reagent

Study of molybdenum (VI) complexation and precipitation by zirconium (IV) in strongly acid medium. Application to nuclear spent fuel dissolution; Etude de la complexation et de la precipitation du molybdene (VI) par le zirconium (IV) en milieu tres acide. Application a la dissolution du combustible nucleaire irradie

Energy Technology Data Exchange (ETDEWEB)

Esbelin, E

1999-07-01

These last years the formation of solid deposits has been observed in the dissolution workshops of the La Hague plant. A sample of the solid was withdrawn for expertise: molybdenum and zirconium are the two major components of the solid, identified as zirconium molybdate. This thesis consisted in the approach of the mechanisms in solution liable to induce precipitate formation. After a bibliographical overview on the chemistry of Mo(VI) in highly acidic solution, this system was studied by absorption spectrophotometry in perchloric medium. The implication of two major forms of Mo(VI) in a dimerization equilibrium was confirmed by this way and by {sup 95}Mo NMR. The principal parameters governing this equilibrium were identified. It is thus shown that the molybdenum dimerization reaction is exothermic. Disturbance of the Mo(VI) system in highly acidic solution by Zr(IV) was also studied. In a restricted experimental field, for which 'conventional' exploitation methodologies had to be adapted to the system, a main complex of stoichiometry 1:1 between Mo(VI) and Zr(IV) was found. The precipitation study of Mo(VI) by Zr(IV) under conditions close to those of the dissolution medium of nuclear spent fuel was undertaken. The main parameters which control precipitation kinetics were identified. The results obtained reveal that precipitation is controlled by a single macroscopic process and therefore can be described by a single equation. The solid obtained is composed of only one phase presenting a Mo:Zr non-stoichiometry when compared to the theoretical formula ZrMo{sub 2}O{sub 7}(OH){sub 2},2H{sub 2}O. At last, on the basis of the research results, a descriptive mechanism of the system is proposed in which intervenes a 1:1 intermediate complex, much more soluble than a probable 2:1 precipitation precursor. (author)

Metal and acidity fluxes controlled by precipitation/dissolution cycles of sulfate salts in an anthropogenic mine aquifer.

Science.gov (United States)

Cánovas, C R; Macías, F; Pérez-López, R

2016-05-01

Underground mine drainages are extremely difficult to study due to the lack of information about the flow path and source proximity in relation to the outflow adit. Geochemical processes controlling metals and acidity fluxes in a complex anthropogenic mine aquifer in SW Spain during the dry and rainy season were investigated by geochemical and statistical tools. High concentrations of acidity, sulfate, metals and metalloids (e.g. Fe, Cu, Zn, As, Cd, Ni, Co) were observed due to intense sulfide oxidation processes. The high residence time inside the anthropogenic aquifer, around 40days, caused the release of significant quantities of metals linked to host rocks (e.g. Al, Ca, Ge, Li, Mg, REE). The most outstanding characteristic of the acid mine drainage (AMD) outflows is the existence of higher Fe/SO4 molar ratios than those theoretical of pyrite (0.50) during most of the monitored period, due to a fire which occurred in 1949 and remained active for decades. Permanent and temporal retention mechanisms of acidity and metals were observed in the galleries. Once released from sulfide oxidation, Pb and As are sorbed on Fe oxyhydroxysulfate or precipitated as low solubility minerals (i.e. anglesite) inside the galleries. The precipitation of evaporitic sulfate salts during the dry season and the subsequent re-dissolution after rainfall control the fluxes of acidity and main metals (i.e. Fe, Mg, Al) from this anthropogenic aquifer. Some elements, such as Cd, Cu, Ni, REE and Zn, are retained in highly soluble sulfate salts while other elements, such as Ge, Pb and Sc, have a lower response to washout processes due to its incorporation in less soluble sulfate salts. In this way, metal concentration during the washout processes would be controlled by the proportion and solubility of each type of evaporitic sulfate salt stored during the dry season. The recovery of metals of economic interest contained in the AMD could help to self-finance the remediation of these waters in

Preventing Precipitation in the ISS Urine Processor

Science.gov (United States)

Muirhead, Dean; Carter, Layne; Williamson, Jill; Chambers, Antja

2017-01-01

The ISS Urine Processor Assembly (UPA) was initially designed to achieve 85% recovery of water from pretreated urine on ISS. Pretreated urine is comprised of crew urine treated with flush water, an oxidant (chromium trioxide), and an inorganic acid (sulfuric acid) to control microbial growth and inhibit precipitation. Unfortunately, initial operation of the UPA on ISS resulted in the precipitation of calcium sulfate at 85% recovery. This occurred because the calcium concentration in the crew urine was elevated in microgravity due to bone loss. The higher calcium concentration precipitated with sulfate from the pretreatment acid, resulting in a failure of the UPA due to the accumulation of solids in the Distillation Assembly. Since this failure, the UPA has been limited to a reduced recovery of water from urine to prevent calcium sulfate from reaching the solubility limit. NASA personnel have worked to identify a solution that would allow the UPA to return to a nominal recovery rate of 85%. This effort has culminated with the development of a pretreatment based on phosphoric acid instead of sulfuric acid. By eliminating the sulfate associated with the pretreatment, the brine can be concentrated to a much higher concentration before calcium sulfate reach the solubility limit. This paper summarizes the development of this pretreatment and the testing performed to verify its implementation on ISS.

Metal transport and remobilisation in a basin affected by acid mine drainage: the role of ochreous amorphous precipitates.

Science.gov (United States)

Consani, Sirio; Carbone, Cristina; Dinelli, Enrico; Balić-Žunić, Tonci; Cutroneo, Laura; Capello, Marco; Salviulo, Gabriella; Lucchetti, Gabriella

2017-06-01

Metal-polluted mine waters represent a major threat to the quality of waters and sediments in a downstream basin. At the confluence between acidic mine waters and the unpolluted waters of the Gromolo Torrent (Liguria, North-West Italy), the massive formation of an ochreous amorphous precipitate takes place. This precipitate forms a soft blanket that covers the torrent bed and can be observed down to its mouth in the sea. The aim of this work is to evaluate the dispersion of metals in the Gromolo Torrent basin from the abandoned Cu-Fe sulphide mine of Libiola to the Ligurian Sea and to assess the metal remobilisation from the amorphous precipitates. The mineralogy of the superficial sediments collected in the torrent bed and the concentrations of different elements of environmental concern (Cu, Zn, Cd, Co, Cr, Mn, Ni, Pb, As, and Sb) were therefore analysed. The results showed that the precipitates contain high concentration of Fe, Al, Cu, and Zn, significantly modifying the bulk chemistry of the Gromolo Torrent sediments. In order to evaluate the possible remobilisation of ecotoxic elements from the amorphous precipitates, bulk leaching tests were performed with both deionised and seawater. Bulk leaching tests with deionised water mobilised primarily high Pb amounts, but also relatively high concentrations of Fe, Al, Cu, and Zn are released in the leachate. In seawater tests, Fe, Al, Cu, and Zn were released in smaller amounts, while other elements like Mn, Cd, Co, and Ni increased in the released fraction. Pb was still strongly released as in deionised water experiments. The results show that the interaction of precipitates and seawater can remobilise high concentrations of metals, thus affecting the surrounding environment.

The production of rare earth elements group via tributyl phosphate extraction and precipitation stripping using oxalic acid

OpenAIRE

Jorjani, Esmaeil; Shahbazi, Malek

2016-01-01

In this study, solvent extraction and precipitation stripping were used to produce rare earth elements (REEs). Tributyl phosphate (TBP) was used to extract yttrium, lanthanum, cerium, and neodymium from an aqueous solution produced by nitric acid leaching of apatite concentrate. In the extraction stage, the effects of TBP concentration, pH, contact time, temperature, and phase ratio were investigated. The results show that about 95%, 90%, 87% and 80% of neodymium, cerium, lanthanum, and yttri...

Determination of trifluoroacetic acid in 1996--1997 precipitation and surface waters in California and Nevada

Energy Technology Data Exchange (ETDEWEB)

Wujcik, C.E.; Cahill, T.M.; Seiber, J.N. [Univ. of Nevada, Reno, NV (United States)

1999-05-15

The atmospheric degradation of three chlorofluorocarbon (CFC) replacement compounds, namely HFC-134a, HCFC-123, and HCFC-124, results in the formation of trifluoroacetic acid (TFA). Concentrations of TFA were determined in precipitation and surface water samples collected in California and Nevada during 1996--1997. Terminal lake systems were found to have concentrations 4--13 times higher than their calculated yearly inputs, providing evidence for accumulation. The results support dry deposition as the primary contributor of TFA to surface waters in arid and semiarid environments. Precipitation samples obtained from three different locations contained 20.7--1530 ng/L with significantly higher concentrations in fogwater over rainwater. Elevated levels of TFA were observed for rainwater collected in Nevada over those collected in California, indicating continual uptake and concentration as clouds move from a semiarid to arid climate. Thus several mechanisms exist, including evaporative concentration, vapor-liquid phase partitioning, lowered washout volumes of atmospheric deposition water, and dry deposition, which may lead to elevated concentrations of TFA in atmospheric and surface waters above levels expected from usual rainfall washout.

Synthesis of WO3 nanoparticles by citric acid-assisted precipitation and evaluation of their photocatalytic properties

International Nuclear Information System (INIS)

Sánchez-Martínez, D.; Martínez-de la Cruz, A.; López-Cuéllar, E.

2013-01-01

Graphical abstract: Display Omitted Highlights: ► WO 3 nanoparticles were synthesized by a simple citric acid-assisted precipitation. ► WO 3 photocatalyst was able to the partial mineralization of rhB, IC and MO. ► WO 3 can be considered as a photocatalyst active under visible light irradiation. -- Abstract: WO 3 nanoparticles were synthesized by citric acid-assisted precipitation method using a 1:1.5 molar ratio of ammonium paratungstate hydrate (H 42 N 10 O 42 W 12 ·xH 2 O):citric acid (C 6 H 8 O 7 ). The formation of monoclinic crystal structure of WO 3 at different temperatures was confirmed by X-ray powder diffraction (XRD). The characterization of the samples synthesized was complemented by transmission electron microscopy (TEM), Brunauer–Emmitt–Teller surface area (BET) and diffuse reflectance spectroscopy (DRS). According to the thermal treatment followed during the synthesis of WO 3 , the morphology of the nanoparticles formed was characterized by rectangular and ovoid shapes. The photocatalytic activity of WO 3 obtained under different experimental conditions was evaluated in the degradation of rhodamine B (rhB), indigo carmine (IC), methyl orange (MO), and Congo red (CR) in aqueous solution under UV and UV–vis radiation. The highest photocatalytic activity was observed in the sample obtained by thermal treatment at 700 °C. In general, the sequence of degradation of the organic dyes was: indigo carmine (IC) > rhodamine B (rhB) > methyl orange (MO) > Congo red (CR). The mineralization degree of organic dyes by WO 3 photocatalysts was determined by total organic carbon analysis (TOC) reaching percentages of mineralization of 82% (rhB), 85% (IC), 28% (MO), and 7% (CR) for 96 h of lamp irradiation.

Inducing mineral precipitation in groundwater by addition of phosphate

Directory of Open Access Journals (Sweden)

Hartmann Thomas

2011-10-01

Full Text Available Abstract Background Induced precipitation of phosphate minerals to scavenge trace elements from groundwater is a potential remediation approach for contaminated aquifers. The success of engineered precipitation schemes depends on the particular phases generated, their rates of formation, and their long term stability. The purpose of this study was to examine the precipitation of calcium phosphate minerals under conditions representative of a natural groundwater. Because microorganisms are present in groundwater, and because some proposed schemes for phosphate mineral precipitation rely on stimulation of native microbial populations, we also tested the effect of bacterial cells (initial densities of 105 and 107 mL-1 added to the precipitation medium. In addition, we tested the effect of a trace mixture of propionic, isovaleric, formic and butyric acids (total concentration 0.035 mM. Results The general progression of mineral precipitation was similar under all of the study conditions, with initial formation of amorphous calcium phosphate, and transformation to poorly crystalline hydroxylapatite (HAP within one week. The presence of the bacterial cells appeared to delay precipitation, although by the end of the experiments the overall extent of precipitation was similar for all treatments. The stoichiometry of the final precipitates as well as Rietveld structure refinement using x-ray diffraction data indicated that the presence of organic acids and bacterial cells resulted in an increasing a and decreasing c lattice parameter, with the higher concentration of cells resulting in the greatest distortion. Uptake of Sr into the solids was decreased in the treatments with cells and organic acids, compared to the control. Conclusions Our results suggest that the minerals formed initially during an engineered precipitation application for trace element sequestration may not be the ones that control long-term immobilization of the contaminants. In

Studies on gadolinium precipitation in moderator system of nuclear reactor

International Nuclear Information System (INIS)

Joshi, Akhilesh C.; Rajesh, Puspalata; Rufus, A.L.; Velmurugan, S.

2015-01-01

Gadolinium is used in the moderator system of many Pressurised Heavy Water Reactors (PHWRs) for start-up, shut-down and reactivity control during operation. It is very much essential to maintain gadolinium concentration in the system as desired. It has been reported that gadolinium gets precipitated in as oxalate in carbonated water under the influence of γ-radiation. Hence, studies were carried out to investigate the effect of dose, presence of other metal ions and metal surfaces on the precipitation of gadolinium. The results showed that the amount of carboxylic acids viz., formic acid and oxalic acid, formed due to radiolysis is dependent on the dose and that the curve passes though a maxima. Gadolinium is added in higher concentration in Advanced Heavy Water Reactor. So, experiments with high concentration of gadolinium were also carried out. Ultra pure water saturated with high purity CO 2 containing gadolinium and desired ion/surface was irradiated with γ-radiation from 60 Co source at 25°C to doses ranging from 2.5-16.6 Mrad. At lower doses, formation of carboxylic acids takes place but as the dose increases, decomposition of these acids starts and hence the concentration Vs dose passes through a maximum. It was found that precipitation of gadolinium as oxalate occurred at lower doses. At higher doses, it was seen that pH of the solution decreases and hence solubility of gadolinium oxalate increases. It was also observed that the amount of gadolinium precipitated varied linearly with the initial concentration of gadolinium varying from 2 ppm to 20 ppm. While for gadolinium concentration from 20 ppm to 400 ppm, gadolinium in particulate form was observed. The amount of carboxylic acids formed depends on the nature of cations present in solution. It was found that the amount of oxalic acid formed in the case of gadolinium was more than that formed in the case of sodium. Presence of metal oxides such as ZrO 2 formed over zircoloy surfaces was found to

Bioavailability of zinc to rats from defatted soy flour, acid-precipitated soy concentrate and neutralized soy concentrate as determined by intrinsic and extrinsic labeling techniques

International Nuclear Information System (INIS)

Ketelsen, S.M.; Stuart, M.A.; Weaver, C.M.; Forbes, R.M.; Erdman, J.W. Jr.

1984-01-01

The bioavailability of 65Zn from intrinsically and extrinsically labeled soy flour, acid-precipitated soy concentrate and neutralized soy concentrate was evaluated in rats. Weanling rats were fed marginally zinc-deficient diets, providing 8 ppm zinc from one of these three soy products, for 7 days. The rats then received a radioactively labeled test meal, identical in composition to the previous diet except that the soy product was either intrinsically or extrinsically labeled with 65Zn. After the test meal the rats were again fed diets the same as those consumed prior to the test meal. Whole-body retention of 65Zn at 24 hours and 12 days as well as 65Zn retained in tibias of rats given meals containing neutralized concentrate-based meals was significantly lower than for rats given meals containing the soy flour or acid-precipitated concentrate. In addition, retention of 65Zn from the extrinsically labeled acid-precipitated concentrate-based meal was significantly higher than from the same product intrinsically labeled. These findings confirm the results of previous feeding studies from which it was suggested that neutralization of soy protein concentrates reduces zinc bioavailability to the rat. In addition, the results are taken to suggest that experimental conditions may influence the validity of the extrinsic labeling technique for zinc

Trends of two decadal precipitation chemistry in a subtropical rainforest in East Asia.

Science.gov (United States)

Chang, Chung-Te; Wang, Chiao-Ping; Huang, Jr-Chuan; Wang, Lih-Jih; Liu, Chiung-Pin; Lin, Teng-Chiu

2017-12-15

Long-term monitoring of precipitation chemistry provides a great opportunity to examine the evolution of air pollutant emissions and effectiveness of air pollution control measures. We evaluated the characteristics and trends of precipitation chemistry at both annual and seasonal scales based on the records of 1994-2013 at Fushan Experimental Forest (FEF) of northeastern Taiwan. The results showed that 77% of the weekly precipitation had pHprecipitation pH and the difference between [SO 4 2 - +NO 3 - ] and [Ca 2+ +NH 4 + ], not just [SO 4 2 - +NO 3 - ], suggesting that precipitation acidity was not solely determined by acidic pollutants but by the balance between acidic pollutants and base cations. We also found temporal decreases of Ca 2+ and NH 4 + concentrations in precipitation which contributed to the low acid neutralization capacity of precipitation. Annual deposition of NO 3 - and SO 4 2- was 23 and 55kgha -1 yr -1 , which is much higher than most forest sites in the industrialized countries suggesting that acid deposition is still a major environmental issue in Taiwan. Annual deposition of NH 4 + , Ca 2+ and NO 3 - showed significant decreasing trends during the 20-year period, which was mostly due to the decreases in the summer deposition associated with air pollution mitigation strategies. Winter deposition showed no decreasing patterns for the same period. The high contribution to annual acid deposition from autumn-winter and spring rains (50%) associated with northeast monsoon implies that long-range transport of anthropogenic emissions from East Asia played a key role on acid depositions at FEF and possibly many areas in the region. Therefore, intergovernmental cooperation is urgently needed to effectively mitigate the threat of acid deposition in East Asia. Copyright © 2017 Elsevier B.V. All rights reserved.

New composite materials prepared by calcium phosphate precipitation in chitosan/collagen/hyaluronic acid sponge cross-linked by EDC/NHS.

Science.gov (United States)

Kaczmarek, B; Sionkowska, A; Kozlowska, J; Osyczka, A M

2018-02-01

Nowadays, fabrication of composite materials based on biopolymers is a rising field due to potential for bone repair and tissue engineering application. Blending of different biopolymers and incorporation of inorganic particles in the blend can lead to new materials with improved physicochemical properties and biocompatibility. In this work 3D porous structures called scaffolds based on chitosan, collagen and hyaluronic acid were obtained through the lyophilization process. Scaffolds were cross-linked by EDC/NHS. Infrared spectra for the materials were made, the percentage of swelling, scaffolds porosity and density, mechanical parameters, thermal stability were studied. Moreover, the scaffolds were used as matrixes for the calcium phosphate in situ precipitation. SEM images were taken and EDX analysis was carried out for calcium and phosphorous content determination in the scaffold. In addition, the adhesion and proliferation of human osteosarcoma SaOS-2 cells was examined on obtained scaffolds. The results showed that the properties of 3D composites cross-linked by EDC/NHS were altered after the addition of 1, 2 and 5% hyaluronic acid. Mechanical parameters, thermal stability and porosity of scaffolds were improved. Moreover, calcium and phosphorous were found in each kind of scaffold. SEM images showed that the precipitation was homogeneously carried in the whole volume of samples. Attachment of SaOS-2 cells to all modified materials was better compared to unmodified control and proliferation of these cells was markedly increased on scaffolds with precipitated calcium phosphate. Obtained materials can provide the support useful in tissue engineering and regenerative medicine. Copyright © 2017 Elsevier B.V. All rights reserved.

Characterization of Lignin Precipitated From The Soda Black Liquor of Oil Palm Empty Fruit Bunch Fibers by Various Mineral Acids

Directory of Open Access Journals (Sweden)

M.N Mohamad Ibrahim

2017-10-01

Full Text Available Soda lignin from oil palm empty fruit bunch was directly isolated by various mineral acids i.e. sulfuric acid, hydrochloric acid, phosphoric acid and nitric acid at three levels of concentration (20% v/v, 60%v/v and concentrated. A comparison study was performed through physicochemical properties and structural features using FT-IR, UV, 13C-NMR and nitrobenzene oxidation. The FT-IR results showed that there is no significant difference between the main structures of the lignin isolated by various acids. However, low concentration of phosphoric acid is preferable because of its highest yield. The S: V: H ratio of 7-15:6-11:1 as evaluated by the nitrobenzene oxidation procedure suggests that soda lignin can be classified as belonging to either the cereal straw on grass type. The UV results indicate that phosphoric acid consistently gave the highest absorbance value among the four acids tested in this study regardless of its concentration level. The C13-FTNMR spectra, suggest that the lignin structure is independent of the type of acid used for precipitation.

Well acidizing

Energy Technology Data Exchange (ETDEWEB)

Street, E H

1980-01-23

The apparatus relates in particular to a well-treating process in which an aqueous acid solution having a pH of < 2 is injected into a subterranean reservoir in a manner such that materials that contain ferric ions are present in the acid and, as the acid reacts within the reservoir and attains a pH exceeding 3, tend to be precipitated as ferric ion-containing solid materials that may plug the pores of the reservoir. Such a precipitation is prevented by dissolving in the acid solution an amount of 5-sulfosalicylic acid which is at least sufficient to sequester significant proportions of ferric ions when the pH of the acid is from 0.5 to 3 but is less than enough to cause a significant salting-out of solid materials, and an amount of citric acid which is at least sufficient to sequester significant proportions of ferric ions when the pH of the acid is from 3 to 6 but is less than enough to precipitate a significant amount of calcium citrate. The amount of the 5-sulfosalicylic acid may be from 0.01 to 0.05 moles/l and the amount of citric acid is from 0.001 to 0.009 moles/l. 11 claims.

Synthesis of WO{sub 3} nanoparticles by citric acid-assisted precipitation and evaluation of their photocatalytic properties

Energy Technology Data Exchange (ETDEWEB)

Sánchez-Martínez, D. [Departamento de Ecomateriales y Energía, Facultad de Ingeniería Civil (UANL), Ciudad Universitaria, C.P. 66451, San Nicolás de los Garza, N.L. (Mexico); Martínez-de la Cruz, A., E-mail: azael70@yahoo.com.mx [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ciudad Universitaria, C.P. 66451, San Nicolás de los Garza, N.L. (Mexico); López-Cuéllar, E. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ciudad Universitaria, C.P. 66451, San Nicolás de los Garza, N.L. (Mexico)

2013-02-15

Graphical abstract: Display Omitted Highlights: ► WO{sub 3} nanoparticles were synthesized by a simple citric acid-assisted precipitation. ► WO{sub 3} photocatalyst was able to the partial mineralization of rhB, IC and MO. ► WO{sub 3} can be considered as a photocatalyst active under visible light irradiation. -- Abstract: WO{sub 3} nanoparticles were synthesized by citric acid-assisted precipitation method using a 1:1.5 molar ratio of ammonium paratungstate hydrate (H{sub 42}N{sub 10}O{sub 42}W{sub 12}·xH{sub 2}O):citric acid (C{sub 6}H{sub 8}O{sub 7}). The formation of monoclinic crystal structure of WO{sub 3} at different temperatures was confirmed by X-ray powder diffraction (XRD). The characterization of the samples synthesized was complemented by transmission electron microscopy (TEM), Brunauer–Emmitt–Teller surface area (BET) and diffuse reflectance spectroscopy (DRS). According to the thermal treatment followed during the synthesis of WO{sub 3}, the morphology of the nanoparticles formed was characterized by rectangular and ovoid shapes. The photocatalytic activity of WO{sub 3} obtained under different experimental conditions was evaluated in the degradation of rhodamine B (rhB), indigo carmine (IC), methyl orange (MO), and Congo red (CR) in aqueous solution under UV and UV–vis radiation. The highest photocatalytic activity was observed in the sample obtained by thermal treatment at 700 °C. In general, the sequence of degradation of the organic dyes was: indigo carmine (IC) > rhodamine B (rhB) > methyl orange (MO) > Congo red (CR). The mineralization degree of organic dyes by WO{sub 3} photocatalysts was determined by total organic carbon analysis (TOC) reaching percentages of mineralization of 82% (rhB), 85% (IC), 28% (MO), and 7% (CR) for 96 h of lamp irradiation.

[Characteristics of precipitation pH and conductivity at Mt. Huang].

Science.gov (United States)

Shi, Chun-e; Deng, Xue-liang; Wu, Bi-wen; Hong, Jie; Zhang, Su; Yang, Yuan-jian

2013-05-01

To understand the general characteristics of pH distribution and pollution in precipitation at Mt. Huang, statistical analyses were conducted for the routine measurements of pH and conductivity (K) at Mt. Huang during 2006-2011. The results showed that: (1) Over the period of study, the annual volume weighted mean (VWM) precipitation pH varied from 4.81 to 5.57, with precipitation acidity strengthening before 2009 and weakening thereafter. The precipitation acidity showed evident seasonal variations, with the VWM pH lowest in winter (4.78), and highest in summer (5.33). The occurrence frequency of acid rain was 46% , accounting for 45% of total rainfalls and with the most frequent pH falling into weak acid to neutral rain. (2) The annual VWM K varied from 16.91 to 27.84 microS x cm(-1), with no evident trend. As for ions pollution, the precipitation was relatively clean at Mt. Huang, with the most frequent K range being below 15 microS x cm(-1), followed by 15-25 microS x cm(-1). From February 2010 to December 2011, precipitation samples were collected on daily basis for ions analysis, as well as pH and K measurement in lab. Detailed comparisons were conducted between the two sets of pH and K, one set from field measurement and the other from lab measurement. The results indicated: (1) The lab measured pH (K) was highly correlated with the field pH (K); however, the lab pH tended to move towards neutral comparing with the corresponding field pH, and the shift range was closely correlated with the field pH and rainfall. The shift range of K from field to lab was highly correlated with the total ion concentration of precipitation. The field K showed evident negative correlation with the field pH with a correlation coefficient of -0.51. (2) When sampling with nylon-polyethylene bags, the statistics showed smaller bias between two sets of pH, with higher correlation coefficient between two sets of K. Furthermore, the lab K also showed evident negative correlation with

Three-decade changes in chemical composition of precipitation in Guangzhou city, southern China: has precipitation recovered from acidification following sulphur dioxide emission control?

Directory of Open Access Journals (Sweden)

Yunting Fang

2013-09-01

Full Text Available We examined if precipitation had recovered from acidification in Guangzhou, the third biggest city in China, and if sulphur deposition in precipitation had decreased, and to what extent if yes, following abatement strategies in sulphur dioxide (SO2 emission and energy use implemented since 2001. SO2 emissions were decreasing steadily since 2001, but a marked recovery of precipitation acidity occurred only since 2005; precipitation pH values decreased from 4.65 in 2001 to 4.34 in 2005 and then increased to 5.08 in 2010, while in the same period acid rain (pH<5.6 frequency increased from 70% to 81% and then decreased to 48%. During this period, the change in pH value and sulphate concentration more reflected the patterns of SO2 emission at provincial and national scales than at the local scale, suggesting that precipitation chemical composition was largely controlled by the emissions of pollutants from surrounding areas of the study city. Since 2001, sulphate deposition in precipitation decreased significantly (by 40% but nitrogen deposition remained unaltered. More importantly, the current sulphur (43 kg S ha−1 yr−1 as sulphate and nitrogen depositions (35 kg N ha−1 yr−1 as ammonium plus nitrate in 2010 were still among the highest in China. These results highlight the fact that ambient sulphur and nitrogen deposition still pose a threat to the health of both terrestrial and aquatic ecosystems. Precipitation may become more acidified in the future because the deposition of alkaline dusts containing calcium is also likely to decrease with stricter SO2 emission control policy and reduced construction activities. Additionally, we recommend that a reduction of emissions of nitrogen and chlorine bearing pollutants is urgently required for complete control on acid deposition.

Pretreating dogwood seedlings with simulated acidic precipitation increases dogwood anthracnose symptoms in greenhouse-laboratory trials

Energy Technology Data Exchange (ETDEWEB)

Anderson, R.L.; Knighten, J. (USDA Forest Service, Resistance Screening Center, Asheville, NC (United States)); Berrange, P.; Lawton, K.A. (USDA Forest Service, Center for Forest Environmental Studies, Dry Branch, GA (United States)); Britton, K.O. (USDA Forest Service, Southeastern Forest Experiment Station, Athens, GA (United States))

1993-01-01

Dogwood anthracnose is the most damaging disease of flowering dogwood (Cornus florida L.) in a large part of the tree's natural range. It is caused by Discula destructiva infection. Previous attempts to inoculate C. florida to produce anthracnose symptoms have met with limited success except when the leaves were pretreated with acidic water, suggesting that acidic precipitation may predispose dogwoods to the disease. This hypothesis was tested in two greenhouse-laboratory studies in which year-old C. florida seedlings were randomly assigned to four treatments of simulated rain (pH 2.5, 3.5, 4.5, and 5.5) in 1989 and 1990. After 10 applications over a 42-d period, the seedlings were moved to a temperature-controlled laboratory, placed in plastic bags, humidified, and sprayed with a spore suspension of five D. destructiva isolates. About 30 d layter, the seedlings were examined for the percentage of leaves exhibiting anthracnose symptoms and disease severity on affected leaves. Both trials showed that as the acidity of the simulated rain increased, the incidence and severity of anthracnose leaf symptoms increased. The 1989 study included a soil lime treatment that showed the same trend but the overall occurrence and severity of symptoms was higher. 17 refs., 5 tabs.

A perspective of stepwise utilisation of Bayer red mud: Step two--Extracting and recovering Ti from Ti-enriched tailing with acid leaching and precipitate flotation.

Science.gov (United States)

Huang, Yanfang; Chai, Wencui; Han, Guihong; Wang, Wenjuan; Yang, Shuzhen; Liu, Jiongtian

2016-04-15

The extraction and recovery of Ti from Ti-enriched tailing with acid leaching and precipitate flotation, as one of the critical steps, was proposed for the stepwise utilization of red mud. The factors influencing acid leaching and precipitate flotation were examined by factorial design. The leaching thermodynamics, kinetics of Ti(4+), Al(3+) and Fe(3+), and the mechanism of selectively Fe(3+) removal using [Hbet][Tf2N] as precipitating reagent were discussed. The extracting of Ti(4+), Al(3+) and Fe(3+) in concentrated H2SO4 is controlled by diffusion reactions, depending mainly upon leaching time and temperature. The maximum extracting efficiency of Ti(4+) is approximately 92.3%, whereas Al(3+) and Fe(3+) leaching are respectively 75.8% and 84.2%. [Hbet][Tf2N], as a precipitating reagent, operates through a coordination mechanism in flotation. The pH value is the key factor influencing the flotation recovery of Ti(4+), whereas the dosage of precipitating reagent is that for Al(3+) recovery. The maximum flotation recovery of Ti(4+) is 92.7%, whereas the maximum Al(3+) recovery is 93.5%. The total recovery rate for extracting and recovering titanium is 85.5%. The liquor with Ti(4+) of 15.5g/L, Al(3+) of 30.4g/L and Fe(3+) of 0.48g/L was obtained for the following hydrolysis step in the integrated process for red mud utilisation. Copyright © 2016 Elsevier B.V. All rights reserved.

Uranium peroxide precipitate drying temperature relationships

Energy Technology Data Exchange (ETDEWEB)

Rodgers, C.; Dyck, B., E-mail: chick_rodgers@cameco.com [Cameco Corp., Saskatoon, SK (Canada)

2010-07-01

Cameco Corporation is in the process of revitalizing the mill at its Key Lake operation in northern Saskatchewan. The current Key Lake process employs ammonia stripping and ammonia precipitation. As part of the revitalization, the company is considering installing strong acid stripping in solvent extraction as used at its Rabbit Lake operation. This change would lead to using hydrogen peroxide for uranium precipitation. As part of the process evaluation, tests were carried out to study how changes in the temperature of an indirect fired dryer affected the properties of uranium peroxide [yellowcake] precipitate. This paper discusses the results of the test work, including the relationships between drying temperature and the following: (author)

Precipitation of plutonium (III) oxalate and calcination to plutonium oxide

International Nuclear Information System (INIS)

Esteban, A.; Orosco, E.H.; Cassaniti, P.; Greco, L.; Adelfang, P.

1989-01-01

The plutonium based fuel fabrication requires the conversion of the plutonium nitrate solution from nuclear fuel reprocessing into pure PuO2. The conversion method based on the precipitation of plutonium (III) oxalate and subsequent calcination has been studied in detail. In this procedure, plutonium (III) oxalate is precipitated, at room temperature, by the slow addition of 1M oxalic acid to the feed solution, containing from 5-100 g/l of plutonium in 1M nitric acid. Before precipitation, the plutonium is adjusted to trivalent state by addition of 1M ascorbic acid in the presence of an oxidation inhibitor such as hydrazine. Finally, the precipitate is calcinated at 700 deg C to obtain PuO2. A flowsheet is proposed in this paper including: a) A study about the conditions to adjust the plutonium valence. b) Solubility data of plutonium (III) oxalate and measurements of plutonium losses to the filtrate and wash solution. c) Characterization of the obtained products. Plutonium (III) oxalate has several potential advantages over similar conversion processes. These include: 1) Formation of small particle sizes powder with good pellets fabrication characteristics. 2) The process is rather insensitive to most process variables, except nitric acid concentration. 3) Ambient temperature operations. 4) The losses of plutonium to the filtrate are less than in other conversion processes. (Author) [es

Comparative study on precipitation methods of yellow-cake from acid leachate of rock phosphate and Its purification

International Nuclear Information System (INIS)

Abow Slama, E. H. Y.

2009-05-01

This study was carried-out to leach uranium from rock phosphate using sulphuric acid in presences of potassium chlorate as an oxidant and to investigate the relative purity of different forms of yellow cakes produced with ammonia ((NH 4 ) 2 U 2 O 7 ), magnesia (UO 3 .xH 2 O) and sodium hydroxide (Na 2 U 2 O 7 ) as precipitants, as well as purification of the products with TBP extraction and matching its impurity levels with specification of the commercial products. Alpha-particle spectrometry was for used for determination of activity concentration of uranium isotopes (''2''3''4U and ''2''3''8U) in rock phosphate, resulting green phosphoric acid solution, and in different forms of the yellow cake from which the equivalent mass concentration of uranium was deduced. Likewise, AAS was used for determination of impurities (Pb, Ni, Cd, Fe, Zn, Mn, and Cu). On the average, the activity concentration of uranium in the rock phosphate was 1468±979 Bq/Kg (119.38±79.66 ppm), and 711±252 Bq/L (57.85±20.46 ppm) in the resulting green solution with corresponding percent of dissolution amounting to 48% which is considered low indicating that the experimental conditions (i.e. dissolution container, temperature, PH, retention time) were not optimal. However, the isotopic ratio (''2''3''4U, ''2''3''8U) in all stages of hydrometallurgical process was not much different from unity indicating lack of fractionation. Crude yellow cakes (hydrate uranium trioxide, ammonium diuranate and sodium diuranate) were precipitated from the green solutions prior to separation of iron and once after iron separation. Although, iron was tested using bipyridine and SCN, it was found in all types of crude samples analyzed this might be attributed to either the quality of the reagent used or inhibition of Fe present in the solution by stronger complexing agent. Uranium mass concentration in crude yellow cakes precipitated before iron separation was found following the order: UO 3 .xH 2 O

The precipitation and effect of nano nitrides in HSLC steel

Institute of Scientific and Technical Information of China (English)

2008-01-01

The existing forms of N and Al in HSLC (high strength low carbon) steel produced by TSCR (thin slab casting and rolling process), the precipitation thermodynamics and kinetics of AlN, and its effects on structure and mechanical property are studied. The experimental results show that only a small quantity of nitrogen is com- bined into AlN in HSLC steel produced by TSCR and most of the nitrogen in steel is still free nitrogen. Aluminum-nitride is mainly precipitated during the period of slow air cooling after coiling, but not during rolling and water cooling. The acid-soluble aluminum has no obvious effect on the grain size and mechanical property of HSLC steel produced by TSCR whose acid-soluble aluminum content is 0.005%―0.043%. The precipitation of AlN is not the main cause of grain refinement of HSLC steel produced by TSCR, nor is AlN the dominating precipitate that has precipitation strengthening effect. The nano nitrides are not pure AlN, but have complex compositions.

A simple procedure for preparing chitin oligomers through acetone precipitation after hydrolysis in concentrated hydrochloric acid.

Science.gov (United States)

Kazami, Nao; Sakaguchi, Masayoshi; Mizutani, Daisuke; Masuda, Tatsuhiko; Wakita, Satoshi; Oyama, Fumitaka; Kawakita, Masao; Sugahara, Yasusato

2015-11-05

Chitin oligomers are of interest because of their numerous biologically relevant properties. To prepare chitin oligomers containing 4-6 GlcNAc units [(GlcNAc)4-6], α- and β-chitin were hydrolyzed with concentrated hydrochloric acid at 40 °C. The reactant was mixed with acetone to recover the acetone-insoluble material, and (GlcNAc)4-6 was efficiently recovered after subsequent water extraction. Composition analysis using gel permeation chromatography and MALDI-TOF mass spectrometry indicated that (GlcNAc)4-6 could be isolated from the acetone-insoluble material with recoveries of approximately 17% and 21% from the starting α-chitin and β-chitin, respectively. The acetone precipitation method is highly useful for recovering chitin oligomers from the acid hydrolysate of chitin. The changes in the molecular size and higher-order structure of chitin during the course of hydrolysis were also analyzed, and a model that explains the process of oligomer accumulation is proposed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Optimization of the conditions for the precipitation of thorium oxalate. II. Minimization of the product losses

International Nuclear Information System (INIS)

Pazukhin, E.M.; Smirnova, E.A.; Krivokhatskii, A.S.; Pazukhina, Yu.L.; Kiselev, P.P.

1987-01-01

The precipitation of thorium as a poorly soluble oxalate was investigated. An equation relating the concentrations of the metal and nitric acid in the initial solution and the amount of precipitant required to minimize the product losses was derived. A graphical solution of the equation is presented for the case where the precipitant is oxalic acid at a concentration of 0.78 M

Seasonal variations of ochreous precipitates in mine effluents in Finland

International Nuclear Information System (INIS)

Kumpulainen, Sirpa; Carlson, Liisa; Raeisaenen, Marja-Liisa

2007-01-01

Ochreous precipitate and water samples were collected from the surroundings of seven closed sulphide mines in Finland. In the Hammaslahti Zn-Cu-Au mine, Otravaara pyrite mine and Paroistenjaervi Cu-W-As mine, the collection was repeated in different seasons to study mineralogical and geochemical variations of precipitates. The sampling was done in 1999-2002 from the ditches and drainage ponds of the tailings and waste rock piles that are susceptible to seasonal changes. Mineralogy of the precipitates was evaluated by X-ray diffraction (XRD) and infrared spectroscopy (IR), and precipitate geochemistry was examined by selective extractions. Schwertmannite (Fe 8 O 8 (OH) 6 SO 4 ) was the most typical Fe hydroxide mineral found. Goethite was almost as common as schwertmannite, was often poorly ordered, and contained up to 10 wt.% of SO 4 . Goethite and schwertmannite were commonly found as mixtures, and they occurred in similar pH and SO 4 concentrations. Ferrihydrite (nominally Fe 5 HO 8 . 4H 2 O) was typically found in areas not influenced by acid mine drainage, and also in acid mine waters with high organic matter or As content. Jarosite (KFe 3 (SO 4 ) 2 (OH) 6 ) was found only in one site. In addition, some gypsum (CaSO 4 . 2H 2 O) and aluminous sulphate precipitates (presumably basaluminite, Al 4 (SO 4 )(OH) 10 . 5H 2 O) were identified. Selective extractions showed that acid extracts Fe tot /S tot -ratios of schwertmannite and goethite samples were similar, but the ratio of oxalate-extractable to total Fe, Fe ox /Fe tot , of goethite samples were lower than those of the schwertmannite samples. Only Al, Si and As were bound to precipitates in substantial amounts, up to several wt.%. In schwertmannites and goethites, Al, Cu, Co, Mn and Zn were mostly structural, substituting for Fe in an Fe oxyhydroxide structure or bound to surface adsorption sites in pores limited by diffusion. In ferrihydrites, heavy metals were also partly bound in adsorbed form dissolving in

Study on the Key Technology of High Purity Strontium Titanate Powder Synthesized from Oxalic Acid Co-sediment Precipitation

Science.gov (United States)

Bi, Xiaoguo; Dong, Yingnan; Li, Yingjie; Niu, Wei; Tang, Jian; Ding, Shuang; Li, Meiyang

2017-09-01

Oxalate coprecipitation is applied in this paper, high purity titanium tetrachloride, and after the purification of strontium chloride, match with a certain concentration of solution, oxalate and strontium chloride and titanium tetrachloride in 1.005:1.000 make strontium titanium mixture ratio, slowly under 60°C to join in oxalic acid solution, aging around 4 h, get oxygen titanium strontium oxalate (SrTiO(C2O4)2 • 4H2 ) precipitation, after washing, drying and other process made oxygen titanium strontium oxalate powder.

Study of fallout by precipitation around an oil-fired power plant

Energy Technology Data Exchange (ETDEWEB)

Granat, L; Rodhe, H

1973-01-01

An investigation into the distribution of deposition by precipitation around an oil-fired power plant on the west coast of Sweden is presented. The measurements cover seven precipitation events during late fall. The samples have been analyzed for sulfur, pH, alkalinity, and sodium. In most precipitation events an additional deposition (above the regional background level) of sulfur and acid has been identified on the leeward side of the source. Compared with the background values, the observed increase was generally less than about 100 percent. As a long-term average the additional deposition of acid by precipitation, due to the power plant, is estimated to be not larger than 10-15 percent within 15 km of the plant. A comparison with emitted quantities shows that 1-6 percent of the sulfur emittted during the precipitation has been deposited within the first 15 km, corresponding to a travel time of 20-60 min. If the comparison is made using the total emission, including the dry periods, this fraction is only a few per mille.

Effect of Aqueous Media on the Recovery of Scandium by Selective Precipitation

Directory of Open Access Journals (Sweden)

Bengi Yagmurlu

2018-05-01

Full Text Available This research presents a novel precipitation method for scandium (Sc concentrate refining from bauxite residue leachates and the effect of aqueous media on this triple-stage successive precipitation process. The precipitation pattern and the precipitation behavior of the constituent elements was investigated using different precipitation agents in three major mineral acid media, namely, H2SO4, HNO3, and HCl in a comparative manner. Experimental investigations showed behavioral similarities between HNO3 and HCl media, while H2SO4 media was different from them because of the nature of the formed complexes. NH4OH was found to be the best precipitation agent in every leaching media to remove Fe(III with low Sc co-precipitation. To limit Sc loss from the system, Fe(III removal was divided into two steps, leading to more than 90% of Fe(III removal at the end of the process. Phosphate concentrates were produced in the final step of the precipitation process with dibasic phosphates which have a strong affinity towards Sc. Concentrates containing more than 50% of ScPO4 were produced in each case from the solutions after Fe(III removal, as described. A flow diagram of the selective precipitation process is proposed for these three mineral acid media with their characteristic parameters.

Microbially Induced Precipitation of Gold(0) Nanoparticles.

Science.gov (United States)

Roh, Yu; Kang, Serku; Park, Bitna; Kim, Yumi

2015-01-01

The objectives of this study were to synthesize gold nanoparticles by biomineralization using metal-reducing bacteria and to characterize their mineralogical properties. The metal-reducing bacteria were able to reduce Au(III) to Au(0) with organic fatty acids as electron donors, as indicated by the color change of the culture solution from colorless gold ions to black precipitates at 25 degrees C. XRD, SEM- and TEM-EDS analyses of the precipitates showed that Au(0) was precipitated and formed at either the cell membrane or extracellularly. The Au(0) nanoparticles were about 200 nm in size and ball-shaped. Biomineralization for elemental Au(0) nanoparticle synthesis may be useful for the recovery of natural gold in natural environments.

Polyfluorinated and perfluorinated chemicals in precipitation and runoff from cities across eastern and central China.

Science.gov (United States)

Zhao, Lijie; Zhou, Meng; Zhang, Tao; Sun, Hongwen

2013-02-01

Twenty-three polychlorinated and perfluorinated compounds (PFCs) were investigated in water phase and particulate matters of 19 precipitation samples (18 snow samples and 1 rain sample) from different cities across eastern and central China collected in February 2010. The PFCs in samples of 9e precipitation events during more than half a year at 1 site in Tianjin and 6 successive samples during 1 precipitation event were measured to elucidate the change of PFC in precipitation. In addition, PFCs in 3 runoffs at different kinds of sites in Tianjin were compared with those in the corresponding precipitation. The results showed that the particulate matters separated from the precipitation contained undetectable PFCs. The total PFC concentration ranged between 4.7 and 152 ng L(-1) in water phase of the precipitation samples, with perfluorooctanoic acid (PFOA) being detected at all of the sampling sites and the dominant PFC at most of the sampling sites. Some potential precursors of environmentally concerned PFCs and their degradation intermediates were measured simultaneously, among which 6:2 fluorotelomer unsaturated carboxylic acid (6:2 FTUCA), 8:2 FTUCA, and  × (3, 4, 5, 7):3 acid [F(CF(2))xCH(2)CH(2)COOH] were measured for the first time in Chinese precipitations; however, their concentrations were all lower than the limits of detection except that 6:2 FTUCA and 8:2 FTUCA could be detected in 3 and 8 precipitation samples, respectively. No clear seasonal variation in PFC concentrations in precipitation was observed during half a year; however, a relatively greater average concentration of total PFCs was observed during winter and summer compared with spring. The concentration of individual PFCs showed an obvious descending trend in the successive samples of the precipitation event. PFOA and perfluorononanoic acid in runoffs collected from different sites showed the following similar pattern-gas station > highway > university campus-whereas the other

Zinc and nickel removal in limestone based treatment of acid mine drainage: The relative role of adsorption and co-precipitation

International Nuclear Information System (INIS)

Miller, Andrew; Wildeman, Thomas; Figueroa, Linda

2013-01-01

Highlights: • Limestone treatment of mining impacted water was simulated in batch reactors. • Zinc and nickel removals were quantified/characterized with a sequential extraction. • Removals were described with a surface complexation and a surface precipitation model. • Extraction/modeling results imply mechanisms beyond adsorption dominate metal removal. - Abstract: Mining influenced water may contain high metal and sulfate loads, and have low pH (acid mine drainage). Removal of these metals prior to environmental discharge is critical to maintain ecosystem vitality. Limestone based passive treatment systems are commonly used for pH neutralization. The same conditions that lead to pH neutralization may also remove a substantial amount of metals from solution, but the connection between treatment conditions and metal removal are not well understood. In this study, zinc and nickel removals are quantified in batch reactor simulated limestone treatment of acid mine drainage. The resulting solid phase is characterized with a sequential extraction procedure, and the removals are interpreted using surface complexation and surface precipitation models. Zinc and nickel removals are closely linked to the initial iron concentration in the mine water, but are also affected by pH, alkalinity, calcium and sulfate concentrations. The surface complexation model was based on literature descriptions of hydrous ferric oxide. In order to obtain a sufficient fit to the data, the surface site density was increased to an unrealistically high value. Uptake data was also fit to an existing surface precipitation model. The values used are similar to those found in previous studies. Both models indicate that adsorption is not the dominant removal process in the treatment system. Using adsorption only models will generally underpredict metal removals within limestone based treatment systems

Decomposition of oxalate precipitates by photochemical reaction

International Nuclear Information System (INIS)

Yoo, J.H.; Kim, E.H.

1998-01-01

A photo-radiation method was applied to decompose oxalate precipitates so that it can be dissolved into dilute nitric acid. This work has been studied as a part of partitioning of minor actinides. Minor actinides can be recovered from high-level wastes as oxalate precipitates, but they tend to be coprecipitated together with lanthanide oxalates. This requires another partitioning step for mutual separation of actinide and lanthanide groups. In this study, therefore, the photochemical decomposition mechanism of oxalates in the presence of nitric acid was elucidated by experimental work. The decomposition of oxalates was proved to be dominated by the reaction with hydroxyl radical generated from the nitric acid, rather than with nitrite ion also formed from nitrate ion. The decomposition rate of neodymium oxalate, which was chosen as a stand-in compound representing minor actinide and lanthanide oxalates, was found to be 0.003 M/hr at the conditions of 0.5 M HNO 3 and room temperature when a mercury lamp was used as a light source. (author)

Decomposition of oxalate precipitates by photochemical reaction

International Nuclear Information System (INIS)

Jae-Hyung Yoo; Eung-Ho Kim

1999-01-01

A photo-radiation method was applied to decompose oxalate precipitates so that it can be dissolved into dilute nitric acid. This work has been studied as a part of partitioning of minor actinides. Minor actinides can be recovered from high-level wastes as oxalate precipitates, but they tend to be coprecipitated together with lanthanide oxalates. This requires another partitioning step for mutual separation of actinide and lanthanide groups. In this study, therefore, some experimental work of photochemical decomposition of oxalate was carried out to prove its feasibility as a step of partitioning process. The decomposition of oxalic acid in the presence of nitric acid was performed in advance in order to understand the mechanistic behaviour of oxalate destruction, and then the decomposition of neodymium oxalate, which was chosen as a stand-in compound representing minor actinide and lanthanide oxalates, was examined. The decomposition rate of neodymium oxalate was found as 0.003 mole/hr at the conditions of 0.5 M HNO 3 and room temperature when a mercury lamp was used as a light source. (author)

Organic acids as analytical reagent: Part 1. Estimation of zirconium by gallic acid

International Nuclear Information System (INIS)

Pande, C.S.; Singh, A.K.; Kumar, Ashok

1975-01-01

Gallic acid has been found to be a selective reagent for the estimation of zirconium. The acid gives crystalline precipitate at pH of 4.8. The precipitate is ignited and weighed as ZrO 2 . Cations like Ca +2 , Ba +2 , Sr +2 , Mn +2 , Co +2 , Ni +2 , Fe +3 do not interfere in the estimation. (author)

Acid Rain. LC Science Tracer Bullet.

Science.gov (United States)

Hollmann, Pauline, Comp.

The term "acid rain," also called "acid precipitation," generally refers to any precipitation having a pH value of less than 5.6. This guide to the literature on acid rain in the collections of the Library of Congress is not necessarily intended to be a comprehensive bibliography. It is designed to provide the reader with a set…

Wet milling versus co-precipitation in magnetite ferrofluid preparation

Directory of Open Access Journals (Sweden)

Almásy László

2015-01-01

Full Text Available Various uses of ferrofluids for technical applications continuously raise the interest in improvement and optimization of preparation methods. This paper deals with preparation of finely granulated magnetite particles coated with oleic acid in hydrocarbon suspensions following either chemical co-precipitation from iron salt precursors or wet milling of micron size magnetite powder with the goal to compare the benefits and disadvantages of each method. Microstructural measurements showed that both methods gave similar magnetite particle size of 10-15 nm. Higher saturation magnetization was achieved for the wet-milled magnetite suspension compared to relatively rapid co-precipitation synthesis. Different efficacies of ferrophase incorporation into kerosene could be related to the different mechanisms of oleic acid bonding to nanoparticle surface. The comparative data show that wet milling represents a practicable alternative to the traditional co-precipitation since despite of longer processing time, chemicals impact on environment can be avoided as well as the remnant water in the final product.

Recovery Ce from Ce - TBP Used Oxalic Acid

International Nuclear Information System (INIS)

Purwani, MV; Subagiono, R.; Suyanti

2007-01-01

Recovery or stripping Ce from Ce - TBP product of monazite sand used oxalic acid. Ce - TBP as organic phase and oxalic acid as aqueous phase and as strong precipitant compound to precipitate metal element. The stripping product as Ce - oxalic precipitate. The influence parameter were percentage of oxalic acid, volume ratio of Ce-TBP with oxalic acid, time and rate of stripping. At stripping of 25 ml Ce - TBP used oxalic acid, the optimum condition were achieve at using 5% oxalic acid, volume ratio of Ce - TBP : 5% oxalic acid = 1 : 1, time of stripping 7.5 minute and rate of stripping 150 rpm. At the optimum condition was obtained the recovery efficiency was 100%. (author)

Correlation between precipitation and geographical location of the δ2H values of the fatty acids in milk and bulk milk powder

Science.gov (United States)

Ehtesham, E.; Baisden, W. T.; Keller, E. D.; Hayman, A. R.; Van Hale, R.; Frew, R. D.

2013-06-01

Hydrogen isotope ratios (δ2H) have become a tool for food traceability and authentication of agricultural products. The principle is that the isotopic composition of the produce is influenced by environmental and biological factors and hence exhibits a spatial differentiation of δ2H. This study investigates the variation in δ2H values of New Zealand milk, both in the bulk powder and individual fatty acids extracted from milk samples from dairy factories across New Zealand. Multivariate statistical analyses were used to test for relationships between δ2H of bulk milk powder, milk fatty acid and geographical location. Milk powder samples from different regions of New Zealand were found to exhibit patterns in isotopic composition similar to the corresponding regional precipitation associated with their origin. A model of δ2H in precipitation was developed based on measurements between 2007 and 2010 at 51 stations across New Zealand (Frew and Van Hale, 2011). The model uses multiple linear regressions to predict daily δ2H from 2 geographic and 5 rain-weighted climate variables from the 5 × 5 km New Zealand Virtual Climate Station Network (VCSN). To approximate collection radius for a drying facility the modelled values were aggregated within a 50 km radius of each dairy factory and compared to observed δ2H values of precipitation and bulk milk powder. Daily δ2H predictions for the period from August to December for the area surrounding the sample collection sites were highly correlated with the δ2H values of bulk milk powder. Therefore the δ2H value of milk fatty acids demonstrates promise as a tool for determining the provenance of milk powders and products where milk powder is an ingredient. Separation of milk powder origin to geographic sub-regions within New Zealand was achieved. Hydrogen isotope measurements could be used to complement traditional tracking systems in verifying point of origin.

Geological and hydrochemical sensitivity of the eastern United States to acid precipitation

Energy Technology Data Exchange (ETDEWEB)

Hendrey, G.R.; Galloway, J.N.; Norton, S.A.; Schofield, C.L.; Shaffer, P.W.; Burns, D.A.

1980-03-01

A new analysis of bedrock geology maps of the eastern US constitutes a simple model for predicting areas which might be impacted by acid precipitation and it allows much greater resolution for detecting sensitivity than has previously been available for the region. Map accuracy has been verified by examining current alkalinities and pH's of waters in several test states, including Maine, New Hampshire, New York, Virginia and North Carolina. In regions predicted to be highly sensitive, alkalinities in upstream sites were generally low. Many areas of the eastern US are pinpointed in which some of the surface waters, especially upstream reaches, may be sensitive to acidification. Pre-1970 data were compared to post-1975 data, revealing marked declines in both alkalinity and pH of sensitive waters of two states tested, North Carolina, where pH and alkalinity have decreased in 80% of 38 streams and New Hampshire, where pH in 90% of 49 streams and lakes has decreased since 1949. These sites are predicted to be sensitive by the geological map on the basis of their earlier alkalinity values. The map is to be improved by the addition of a soils component.

Selective Precipitation of Thorium lodate from a Tartaric Acid-Hydrogen Peroxide Medium Application to Rapid Spectrophotometric Determination of Thorium in Silicate Rocks and in Ores

Science.gov (United States)

Grimaldi, F.S.

1957-01-01

This paper presents a selective iodate separation of thorium from nitric acid medium containing d-tartaric acid and hydrogen peroxide. The catalytic decomposition of hydrogen peroxide is prevented by the use of 8quinolinol. A few micrograms of thorium are separated sufficiently clean from 30 mg. of such oxides as cerium, zirconium, titanium, niobium, tantalum, scandium, or iron with one iodate precipitation to allow an accurate determination of thorium with the thoronmesotartaric acid spectrophotometric method. The method is successful for the determination of 0.001% or more of thorium dioxide in silicate rocks and for 0.01% or more in black sand, monazite, thorite, thorianite, eschynite, euxenite, and zircon.

Novel method for concentrating and drying polymeric nanoparticles: hydrogen bonding coacervate precipitation.

Science.gov (United States)

D'Addio, Suzanne M; Kafka, Concepcion; Akbulut, Mustafa; Beattie, Patrick; Saad, Walid; Herrera, Margarita; Kennedy, Michael T; Prud'homme, Robert K

2010-04-05

Nanoparticles have significant potential in therapeutic applications to improve the bioavailability and efficacy of active drug compounds. However, the retention of nanometer sizes during concentrating or drying steps presents a significant problem. We report on a new concentrating and drying process for poly(ethylene glycol) (PEG) stabilized nanoparticles, which relies upon the unique pH sensitive hydrogen bonding interaction between PEG and polyacid species. In the hydrogen bonding coacervate precipitation (HBCP) process, PEG protected nanoparticles rapidly aggregate into an easily filterable precipitate upon the addition various polyacids. When the resulting solid is neutralized, the ionization of the acid groups eliminates the hydrogen bonded structure and the approximately 100 nm particles redisperse back to within 10% of their original size when poly(acrylic acid) and citric acid are used and 45% when poly(aspartic acid) is used. While polyacid concentrations of 1-5 wt % were used to form the precipitates, the incorporation of the acid into the PEG layer is approximately 1:1 (acid residue):(ethylene oxide unit) in the final dried precipitate. The redispersion of dried beta-carotene nanoparticles protected with PEG-b-poly(lactide-co-glycolide) polymers dried by HBCP was compared with the redispersion of particles dried by freeze-drying with sucrose as a cryprotectant, spray freeze-drying, and normal drying. Freeze-drying with 0, 2, and 12 wt % sucrose solutions resulted in size increases of 350%, 50%, and 6%, respectively. Spray freeze-drying resulted in particles with increased sizes of 50%, but no cryoprotectant and only moderate redispersion energy was required. Conventional drying resulted in solids that could not be redispersed back to nanometer size. The new HBCP process offers a promising and efficient way to concentrate or convert nanoparticle dispersions into a stable dry powder form.

Relationships between precipitation and surface water chemistry in three Carolina bays

International Nuclear Information System (INIS)

Monegue, R.L.; Jagoe, C.H.

1995-01-01

Carolina Bays are shallow freshwater wetlands, the only naturally occurring lentic systems on the southeastern coastal plain. Bays are breeding sites for many amphibian species, but data on precipitation/surface water relationships and long-term chemical trends are lacking. Such data are essential to interpret major fluctuations in amphibian populations. Surface water and bulk precipitation were sampled bi-weekly for over two years at three bays along a 25 km transect on the Savannah River Site in South Carolina. Precipitation chemistry was similar at all sites; average pH was 4.56, and the major ions were H + (30.8 % of total), and SO 4 (50.3% of total). H + was positively correlated with SO 4 , suggesting the importance of anthropogenic acids to precipitation chemistry. All three bays, Rainbow Bay (RB), Thunder Bay (TB), and Ellenton Bay (EB), contained soft (specific conductivity 5--90 microS/cm), acidic water (pH 4.0--5.9) with DOM from 4--40 mg/L. The major cation for RB, TB, and EB, respectively, was: Mg (30.8 % of total); Na (27% of total); and Ca (34.2% of total). DOM was the major anion for all bays, and SO 4 represented 13 to 28 % of total anions. H + was not correlated to DOM or SO, in RB; H + was positively correlated to DOM and SO 4 in TB, and negatively correlated to DOM and SO 4 in EB. Different biogeochemical processes probably control pH and other chemical variables in each bay. While surface water H + was not directly correlated with precipitation H + , NO 3 , or SO 4 , precipitation and shallow groundwater are dominant water sources for these bays. Atmospheric inputs of anthropogenic acids and other chemicals are important factors influencing bay chemistry

Thermal behaviour of natural and synthetic iron precipitates from mine drainage

Czech Academy of Sciences Publication Activity Database

Pulišová, Petra; Máša, B.; Michalková, E.; Večerníková, Eva; Maříková, Monika; Bezdička, Petr; Murafa, Nataliya; Šubrt, Jan

2014-01-01

Roč. 116, č. 2 (2014), s. 625-632 ISSN 1388-6150 R&D Projects: GA MŠk 7AMB12SK155 Institutional support: RVO:61388980 Keywords : Thermogravimetry * Differential thermal analysis * X-ray diffraction analysis * Acid mine drainage * Iron precipitates * Precipitation with urea Subject RIV: CA - Inorganic Chemistry Impact factor: 2.042, year: 2014

Understanding Acid Rain

Science.gov (United States)

Damonte, Kathleen

2004-01-01

The term acid rain describes rain, snow, or fog that is more acidic than normal precipitation. To understand what acid rain is, it is first necessary to know what an acid is. Acids can be defined as substances that produce hydrogen ions (H+), when dissolved in water. Scientists indicate how acidic a substance is by a set of numbers called the pH…

Recovery of yttrium from fluorescent powder of cathode ray tube, CRT: Zn removal by sulphide precipitation

International Nuclear Information System (INIS)

Innocenzi, Valentina; De Michelis, Ida; Ferella, Francesco; Beolchini, Francesca; Kopacek, Bernd; Vegliò, Francesco

2013-01-01

Highlights: • Treatment of fluorescent powder of CRT waste. • Factorial experimental designs to study acid leaching of fluorescent powder and the purification of leach liquors. • Recover of yttrium by precipitation using oxalic acid. • Suitable flowsheet to recover yttrium from fluorescent powder. - Abstract: This work is focused on the recovery of yttrium and zinc from fluorescent powder of cathode ray tube (CRT). Metals are extracted by sulphuric acid in the presence of hydrogen peroxide. Leaching tests are carried out according to a 2 2 full factorial plan and the highest extraction yields for yttrium and zinc equal to 100% are observed under the following conditions: 3 M of sulphuric acid, 10% v/v of H 2 O 2 concentrated solution at 30% v/v, 10% w/w pulp density, 70 °C and 3 h of reaction. Two series of precipitation tests for zinc are carried out: a 2 2 full factorial design and a completely randomized factorial design. In these series the factors investigated are pH of solution during the precipitation and the amount of sodium sulphide added to precipitate zinc sulphide. The data of these tests are used to describe two empirical mathematical models for zinc and yttrium precipitation yields by regression analysis. The highest precipitation yields for zinc are obtained under the following conditions: pH equal to 2–2.5% and 10–12% v/v of Na 2 S concentrated solution at 10% w/v. In these conditions the coprecipitation of yttrium is of 15–20%. Finally further yttrium precipitation experiments by oxalic acid on the residual solutions, after removing of zinc, show that yttrium could be recovered and calcined to obtain the final product as yttrium oxide. The achieved results allow to propose a CRT recycling process based on leaching of fluorescent powder from cathode ray tube and recovery of yttrium oxide after removing of zinc by precipitation. The final recovery of yttrium is 75–80%

Recovery of yttrium from fluorescent powder of cathode ray tube, CRT: Zn removal by sulphide precipitation

Energy Technology Data Exchange (ETDEWEB)

Innocenzi, Valentina, E-mail: valentina.innocenzi1@univaq.it [Department of Industrial Engineering and Information and Economy, University of L’Aquila, Via Giovanni Gronchi n.18, Nucleo Ind.le di Pile, 67100 L’Aquila (Italy); De Michelis, Ida; Ferella, Francesco [Department of Industrial Engineering and Information and Economy, University of L’Aquila, Via Giovanni Gronchi n.18, Nucleo Ind.le di Pile, 67100 L’Aquila (Italy); Beolchini, Francesca [Department of Marine Sciences, Polytechnic Institute of Marche, Via Brecce Bianche, 60131 Ancona (Italy); Kopacek, Bernd [SAT, Austrian Society for Systems Engineering and Automation, Gurkasse 43/2, A-1140 Vienna (Austria); Vegliò, Francesco [Department of Industrial Engineering and Information and Economy, University of L’Aquila, Via Giovanni Gronchi n.18, Nucleo Ind.le di Pile, 67100 L’Aquila (Italy)

2013-11-15

Highlights: • Treatment of fluorescent powder of CRT waste. • Factorial experimental designs to study acid leaching of fluorescent powder and the purification of leach liquors. • Recover of yttrium by precipitation using oxalic acid. • Suitable flowsheet to recover yttrium from fluorescent powder. - Abstract: This work is focused on the recovery of yttrium and zinc from fluorescent powder of cathode ray tube (CRT). Metals are extracted by sulphuric acid in the presence of hydrogen peroxide. Leaching tests are carried out according to a 2{sup 2} full factorial plan and the highest extraction yields for yttrium and zinc equal to 100% are observed under the following conditions: 3 M of sulphuric acid, 10% v/v of H{sub 2}O{sub 2} concentrated solution at 30% v/v, 10% w/w pulp density, 70 °C and 3 h of reaction. Two series of precipitation tests for zinc are carried out: a 2{sup 2} full factorial design and a completely randomized factorial design. In these series the factors investigated are pH of solution during the precipitation and the amount of sodium sulphide added to precipitate zinc sulphide. The data of these tests are used to describe two empirical mathematical models for zinc and yttrium precipitation yields by regression analysis. The highest precipitation yields for zinc are obtained under the following conditions: pH equal to 2–2.5% and 10–12% v/v of Na{sub 2}S concentrated solution at 10% w/v. In these conditions the coprecipitation of yttrium is of 15–20%. Finally further yttrium precipitation experiments by oxalic acid on the residual solutions, after removing of zinc, show that yttrium could be recovered and calcined to obtain the final product as yttrium oxide. The achieved results allow to propose a CRT recycling process based on leaching of fluorescent powder from cathode ray tube and recovery of yttrium oxide after removing of zinc by precipitation. The final recovery of yttrium is 75–80%.

Oxidative Precipitation of Manganese from Acid Mine Drainage by Potassium Permanganate

Directory of Open Access Journals (Sweden)

Regeane M. Freitas

2013-01-01

Full Text Available Although oxidative precipitation by potassium permanganate is a widely recognised process for manganese removal, research dealing with highly contaminated acid mine drainage (AMD has yet to be performed. The present study investigated the efficiency of KMnO4 in removing manganese from AMD effluents. Samples of AMD that originated from inactive uranium mine in Brazil were chemically characterised and treated by KMnO4 at pH 3.0, 5.0, and 7.0. Analyses by Raman spectroscopy and geochemical modelling using PHREEQC code were employed to assess solid phases. Results indicated that the manganese was rapidly oxidised by KMnO4 in a process enhanced at higher pH. The greatest removal, that is, 99%, occurred at pH 7.0, when treated waters presented manganese levels as low as 1.0 mg/L, the limit established by the Brazilian legislation. Birnessite (MnO2, hausmannite (Mn3O4, and manganite (MnOOH were detected by Raman spectroscopy. These phases were consistently identified by the geochemical model, which also predicted phases containing iron, uranium, manganese, and aluminium during the correction of the pH as well as bixbyite (Mn2O3, nsutite (MnO2, pyrolusite (MnO2, and fluorite (CaF2 following the KMnO4 addition.

Precipitation of iron (III) using magnesium oxide in fluidized bed

International Nuclear Information System (INIS)

Esteban-Bocardo, P. A.; Ferreira-Rocha, S. D.

2006-01-01

A process for iron (III) removal by hydroxide precipitation from and acid synthetic inorganic effluent using magnesium oxide as an alternative precipitant agent in a fluidized bed was developed. An acid synthetic inorganic effluent containing 100 and 200 mg/l of ferric ions (pH=1.0) was continuously fed up to the acrylic column (30 cm high and 2 cm diameter) during 180 minutes. Magnesium oxide pulp (3% v/v) was injected at the beginning of the experiment in order to allow the iron hydroxides precipitation. The concentration and pH profiles agreed in their curves, while the pH profile rose,the concentration profile decreased and a high percentage of iron removal /higher to 99%) was reached. Extremely low iron concentrations have been reached, thus permitting to attend to the environmental standard of 10.0 mg/l for discharge of effluent containing ferric ions established by the law DN 10/86 of COPAM (Conselho de Politica Ambiental do Estado de Minas Gerais-Brazil). (Author)

Lanthanide-alkali double sulfate precipitation from strong sulfuric acid NiMH battery waste leachate.

Science.gov (United States)

Porvali, Antti; Wilson, Benjamin P; Lundström, Mari

2018-01-01

In NiMH battery leaching, rare earth element (REE) precipitation from sulfate media is often reported as being a result of increasing pH of the pregnant leach solution (PLS). Here we demonstrate that this precipitation is a phenomenon that depends on both Na + and SO 4 2- concentrations and not solely on pH. A two-stage leaching for industrially crushed NiMH waste is performed: The first stage consists of H 2 SO 4 leaching (2 M H 2 SO 4 , L/S = 10.4, V = 104 ml, T = 30 °C) and the second stage of H 2 O leaching (V = 100 ml, T = 25 °C). Moreover, precipitation experiments are separately performed as a function of added Na 2 SO 4 and H 2 SO 4 . During the precipitation, higher than stoichiometric quantities of Na to REE are utilized and this increase in both precipitation reagent concentrations results in an improved double sulfate precipitation efficiency. The best REE precipitation efficiencies (98-99%) - achieved by increasing concentrations of H 2 SO 4 and Na 2 SO 4 by 1.59 M and 0.35 M, respectively - results in a 21.8 times Na (as Na 2 SO 4 ) and 58.3 times SO 4 change in stoichiometric ratio to REE. Results strongly indicate a straightforward approach for REE recovery from NiMH battery waste without the need to increase the pH of PLS. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Adsorption of arsenic by iron rich precipitates from two coal mine drainage sites on the West Coast of New Zealand

International Nuclear Information System (INIS)

Rait, R.; Trumm, D.; Pope, J.; Craw, D.; Newman, N.; MacKenzie, H.

2010-01-01

Dissolved As can be strongly adsorbed to fine grained Fe(III) minerals such as hydroxides, oxyhydroxides and hydroxysulphates. Therefore precipitates that form during neutralisation or treatment of acid mine drainage have potential to be useful for treatment of As-contaminated water because acid mine drainage is often Fe rich. We tested the adsorption properties of Fe(III) rich precipitates from two West Coast coal mines with As-contaminated water from an historic gold ore processing site near Reefton. Precipitates were collected from distinctly different settings, an active acid mine drainage treatment plant at Stockton mine and the neutralisation/oxidation zone of acid mine drainage discharge at the abandoned Blackball Coal Mine. The two mine sites produce precipitates with different compositions and mineralogy. Arsenic adsorption onto precipitates from each site was determined in batch and column tests under laboratory conditions. Batch experiments indicate As adsorption occurs rapidly during the first 5 h and reaches equilibrium after 24 h. At equilibrium, and for a dosing ratio of 50 g of precipitate per litre of water, As concentrations decreased from 99 mg/L to 0.0080 mg/L with precipitates from Stockton and to 0.0017 mg/L with precipitates from Blackball. Arsenic adsorption capacity is up to 12 mg/g on precipitates from Stockton sludge and 74 mg/g on precipitates from Blackball. The Blackball precipitate adsorbs more As than precipitates from Stockton which is probably due to the higher Fe oxide content but pH and surface structure could also play a role. The column experiment confirmed that adsorption of As from a continuous waste stream onto these precipitates is possible, and that passive remediation using this waste product mixed with gravel to enhance permeability could be a viable approach at As-contaminated mine sites. (author). 56 refs., 10 figs., 6 tabs.

Mathematical modeling of the formation of sedimentary acid precipitation in the atmosphere in view of the evaporation of moisture from their surface

Directory of Open Access Journals (Sweden)

Gvozdyakov Dmitry

2017-01-01

Full Text Available The article presents the results of numeric simulation of the formation of sedimentary acid precipitation in the atmosphere taking into account the evaporation of moisture from their surfaces. It is established that the joint condensation of vapors of sulfuric anhydride and water vapor, given the flow of solar energy and the evaporation process significantly slows the growth of drops. The possibility of achieving the underlying surface by the formed sediments is analyzed.

A new technique for production of yellow cake with double precipitation

International Nuclear Information System (INIS)

Li Jianhua; Zeng Yijun; Li Shangyuan; Kong Guiying

1997-01-01

The author presents a new technique for production of yellow cake with double precipitation, thus solving a series of problems for precipitating uranium with traditional double precipitation. The new technique can not only remove ferric ions and sulfate radicals but also make solid-liquid separation easy, utilize effectively the sulfuric acid produced in ferric ions precipitation process, and increase uranium concentration of leaching liquor. To take it as producing yellow cake will save investment, simplify operation, and cut down the consumption of raw materials and energies. It is more competitive than ion-exchange or solvent extraction in the process of extracting-purifying and preparing yellow cake

Synchrotron X-ray induced solution precipitation of nanoparticles

CERN Document Server

Lee, H J; Hwu, Y; Tsai, W L

2003-01-01

By irradiating a solution in electroless Ni deposition using synchrotron X-rays, Ni composite was found to nucleate homogeneously and eventually precipitate in the form of nanoparticles. The size of the nanoparticles precipitated is rather uniform (100-300 nm depending on the applied temperature). By the addition of an organic acid, well-dispersed nanoparticles could be effectively deposited on glass substrate. The hydrated electrons (e sub a sub q sup -), products of radiolysis of water molecules by synchrotron X-rays, may be responsible for the effective reduction of the metal ions, resulting in homogeneous nucleation and nanoparticle formation. Our results suggest that synchrotron X-ray can be used to induce solution precipitation of nanoparticles and therefore lead to a new method of producing nanostructured particles and coating.

Preparation of porous carboxymethyl chitosan grafted poly (acrylic acid) superabsorbent by solvent precipitation and its application as a hemostatic wound dressing

Energy Technology Data Exchange (ETDEWEB)

Chen, Yu, E-mail: cylsy@163.com [School of Material Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Zhang, Yong [School of Life Science, Beijing Institute of Technology, Beijing 100081 (China); Wang, Fengju [School of Material Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Meng, Weiwei; Yang, Xinlin [School of Life Science, Beijing Institute of Technology, Beijing 100081 (China); Li, Peng [School of Material Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Jiang, Jianxin [State Key Laboratory of Trauma Burns and Combined Injury, The Third Military Medical University, Chongqing 400042 (China); Tan, Huimin [School of Material Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Zheng, Yongfa [Guangdong Fuyang Biotechnology Co., Ltd., Heyuan, Guangdong 517000 (China)

2016-06-01

The volume phase transition of a hydrogel initiated by shrinking may result in complex patterns on its surface. Based on this unique property of hydrogel, we have developed a novel solvent precipitation method to prepare a kind of novel superabsorbent polymers with excellent hemostatic properties. A porous carboxymethyl chitosan grafted poly (acrylic acid) (CMCTS-g-PAA) superabsorbent polymer was prepared by precipitating CMCTS-g-PAA hydrogel with ethanol. Its potential application in hemostatic wound dressing was investigated. The results indicate that the modified superabsorbent polymer is non-cytotoxic. It showed a high swelling capacity and better hemostatic performance in the treatments of hemorrhage model of ear artery, arteria cruralis and spleen of the New Zealand white rabbit than the unmodified polymer and other commonly used clinic wound dressings. The hemostatic mechanism of the porous CMCTS-g-PAA polymer was also discussed. - Highlights: • The novel solvent precipitation method was developed to prepare the porous superabsorbent polymer. • The swelling rate was promoted and the harmful residual monomer was leached after modification. • The modified polymer showed good biological safety. • It showed good hemostasis to arterial hemorrhage model of the animal. • The hemostatic mechanism of the modified superabsorbent polymer was discussed.

Cs separation from nitric acid solutions of radioactive waste

International Nuclear Information System (INIS)

Heckmann, K.; Pieronczyk, W.; Strnad, J.; Feldmaier, F.

1989-01-01

It was the objective of this study to selectively separate active caesium (Cs-134 and Cs-137) from acid radioactive waste solutions (especially MAW and HAWC). The following 'strategy' was designed for a separation process: synthesis of reagents which are acid-resistant and selective for caesium; precipitation of Cs + and separation of the precipitates by filtration or centrifugation or precipitation of Cs + and separation of the precipitates by flotation; caesium separation by liquid-liquid extraction. As precipitating agents, sodium tetraphenylborate (kalignost) and several of its fluorine derivatives were examined. (orig./RB) [de

Research and performance evaluation on an HA integrated acid system for sandstone acidizing

Directory of Open Access Journals (Sweden)

Liqiang Zhao

2018-03-01

Full Text Available When the conventional sandstone acidizing technologies are adopted, many slugs are needed in the injection of prepad fluid, treatment fluid and postpad fluid, and consequently the production and operation suffers inconveniences and difficulties. In view of this, a kind of HA integrated acid system which is mainly composed of organic polybasic acids (HA+HCl + HF and an efficient organic solvent was developed in this paper based on the idea of integrated acid replacing ''multiple steps'' and high efficiency and intensification. Via this HA integrated acid system, the complicated blockage in sandstone reservoirs can be removed effectively. Then, experiments were carried out on this system to evaluate its performance in terms of its retardance, organic blockage dissolution, chelating and precipitation inhibition. It is indicated that this new system can not only realize the acidizing of conventional integrated acid, but also present a good retarding performance by controlling H+ multi-stage ionization step by step and by forming silica acid-aluminum phosphonate film on the surface of clay minerals; that via this new HA integrated acid system, the organic blockage can be removed efficiently; and that it is wider in pH solution range than conventional APCs (aminopolycarboxyliates chelants, stronger in chelating capacity of Ca2+, Mg2+ and Fe3+ than conventional chelants (e.g. EDTA, NTA and DTPA, and better in precipitation inhibition on metal fluoride, fluosilicic acid alkali metal, fluoaluminic acid alkali metal and hydroxide than multi-hydrogen acid, fluoboric acid and mud acid systems. These research results provide a technical support for the plugging removal in high-temperature deep oil and gas reservoirs. Keywords: Organic polybasic acid, Integrated acid, Retardance, Chelating, Precipitation, Acidizing, Sandstone, Reservoir

Characterization of the precipitates formed during the denitration of simulated HRLW

International Nuclear Information System (INIS)

Music, S.; Ristic, M.; Popovic, S.

1989-01-01

The denitration of several chemical compositions of simulated highly radioactive liquid waste (HRLW) was performed using formic acid as reducing agent. Precipitates formed during the denitration of simulated HRLW were analyzed using x-ray diffraction and 57 Fe Moessbauer spectroscopy. Goethite and amorphous fractions were the principal phases in these precipitates. It was found that the chemical composition of HRLW and the experimental conditions of denitration had more influence on the crystal formation and the particle size than on the phase composition of the precipitates. (author) 27 refs.; 6 figs.; 6 tabs

Whither Acid Rain?

Directory of Open Access Journals (Sweden)

Peter Brimblecombe

2000-01-01

Full Text Available Acid rain, the environmental cause célèbre of the 1980s seems to have vanished from popular conscience. By contrast, scientific research, despite funding difficulties, has continued to produce hundreds of research papers each year. Studies of acid rain taught much about precipitation chemistry, the behaviour of snow packs, long-range transport of pollutants and new issues in the biology of fish and forested ecosystems. There is now evidence of a shift away from research in precipitation and sulfur chemistry, but an impressive theoretical base remains as a legacy.

Complete covalent structure of statherin, a tyrosine-rich acidic peptide which inhibits calcium phosphate precipitation from human parotid saliva.

Science.gov (United States)

Schlesinger, D H; Hay, D I

1977-03-10

The complete amino acid sequence of human salivary statherin, a peptide which strongly inhibits precipitation from supersaturated calcium phosphate solutions, and therefore stabilizes supersaturated saliva, has been determined. The NH2-terminal half of this Mr=5380 (43 amino acids) polypeptide was determined by automated Edman degradations (liquid phase) on native statherin. The peptide was digested separately with trypsin, chymotrypsin, and Staphylococcus aureus protease, and the resulting peptides were purified by gel filtration. Manual Edman degradations on purified peptide fragments yielded peptides that completed the amino acid sequence through the penultimate COOH-terminal residue. These analyses, together with carboxypeptidase digestion of native statherin and of peptide fragments of statherin, established the complete sequence of the molecule. The 2 serine residues (positions 2 and 3) in statherin were identified as phosphoserine. The amino acid sequence of human salivary statherin is striking in a number of ways. The NH2-terminal one-third is highly polar and includes three polar dipeptides: H2PO3-Ser-Ser-H2PO3-Arg-Arg-, and Glu-Glu-. The COOH-terminal two-thirds of the molecule is hydrophobic, containing several repeating dipeptides: four of -Gn-Pro-, three of -Tyr-Gln-, two of -Gly-Tyr-, two of-Gln-Tyr-, and two of the tetrapeptide sequence -Pro-Tyr-Gln-Pro-. Unusual cleavage sites in the statherin sequence obtained with chymotrypsin and S. aureus protease were also noted.

DEGREE OF ACIDIFICATION OF PRECIPITATION IN BIELSKO-BIAŁA REGION

Directory of Open Access Journals (Sweden)

Henryk Kasza

2014-10-01

Full Text Available In the paper results of long-term studies on acidification of water precipitation conducted in seven research points located near Bielsko-Biała were introduced. In each point period of study lasted ca. 1 year. The research was performed in the years 2002-2010. The range of pH of precipitation varied between 3.35 to 7.22. Majority of precipitation samples, because approximately 86% had pH < 5.6 i.e. lower than natural level, which indicated the presence of acidifying substances. Amongst samples of precipitation 47.6% were significantly and strongly acidic i.e. pH < 4.5. The rainwater with pH < 5.6 was more frequent than in more industrialized part of Silesian voivodship. In the investigated area pH of precipitation is mainly under influence of pollution flowing from west and southern-west and local sources of its emission.

Process for recovering yttrium and lanthanides from wet-process phosphoric acid

Energy Technology Data Exchange (ETDEWEB)

Janssen, J.A.; Weterings, C.A.

1983-06-28

Process for recovering yttrium and lanthanides from wet-process phosphoric acid by adding a flocculant to the phosphoric acid, separating out the resultant precipitate and then recovering yttrium and lanthanides from the precipitate. Uranium is recovered from the remaining phosphoric acid.

Speciation and precipitation of heavy metals in high-metal and high-acid mine waters from the Iberian Pyrite Belt (Portugal).

Science.gov (United States)

Durães, Nuno; Bobos, Iuliu; da Silva, Eduardo Ferreira

2017-02-01

Acid mine waters (AMW) collected during high- and low-flow water conditions from the Lousal, Aljustrel, and São Domingos mining areas (Iberian Pyrite Belt) were physicochemically analyzed. Speciation calculation using PHREEQC code confirms the predominance of Me n+ and Me-SO 4 species in AMW samples. Higher concentration of sulfate species (Me-SO 4 ) than free ion species (Me n+ , i.e., Al, Fe, and Pb) were found, whereas opposite behavior is verified for Mg, Cu, and Zn. A high mobility of Zn than Cu and Pb was identified. The sulfate species distribution shows that Fe 3+ -SO 4 2- , SO 4 2- , HSO 4 - , Al-SO 4 , MgSO 4 0 , and CaSO 4 0 are the dominant species, in agreement with the simple and mixed metal sulfates and oxy-hydroxysulphates precipitated from AMW. The saturation indices (SI) of melanterite and epsomite show a positive correlation with Cu and Zn concentrations in AMW, which are frequently retained in simple metal sulfates. Lead is well correlated with jarosite and alunite (at least in very acid conditions) than with simple metal sulfates. The Pb for K substitution in jarosite occurs as increasing Pb concentration in solution. Lead mobility is also controlled by anglesite precipitation (a fairly insoluble sulfate), where a positive correlation was ascertained when the SI approaches equilibrium. The zeta potential of AMW decreased as pH increased due to colloidal particles aggregation, where water species change from SO 4 2- to OH - species during acid to alkaline conditions, respectively. The AMW samples were supersaturated in schwertmannite and goethite, confirmed by the Me n+ -SO 4 , Me n+ -Fe-O-OH, or Me n+ -S-O-Fe-O complexes identified by attenuated total reflectance infrared spectroscopy (ATR-IR). The ATR-IR spectrum of an AMW sample with pH 3.5 (sample L1) shows well-defined vibration plans attributed to SO 4 tetrahedron bonded with Fe-(oxy)hydroxides and the Me n+ sorbed by either SO 4 or Fe-(oxy)hydroxides. For samples with lower pH values (p

Chemical composition of precipitation in a forest area of Chongqing, southwest China

International Nuclear Information System (INIS)

Zhang, F.; Zhang, J.; Zhang, H.; Ogura, N.; Ushikubo, A.

1996-01-01

Experiments were carried out in Chongqing - a city seriously damaged by acid precipitation in southwest China - to explore chemical compositions of open bulk precipitation, throughfall and stemflow in a Masson pine (Pinus massoniana) forest. The results showed that annual mean pH values of and annual ion depositions in the three types of rain water were 4.47 and 50.6 g m -2 , 3.82 and 69.7 g m -2 m and 2.92 and 0.215 g m -2 respectively. pH values demonstrated an obvious seasonal variation; they were lower in winter than in the rest of the year. Ca 2+ and NH 4 + together made up more than 80% of the total cation, while SO 4 2- alone contributed over 90% to the total anion. This high level of SO 4 2- in rain water in Congqing, which outran those found in other cities in China, was closely related to the combustion of locally produced coal that contains 3 to 5% sulphur. Thus, acid precipitation in Chongqing is of a typical sulphuric-acid type. 6 refs., 3 figs., 6 tabs

Amino acids and glycine ethyl ester as new crystallization reagents for lysozyme

International Nuclear Information System (INIS)

Ito, Len; Shiraki, Kentaro; Yamaguchi, Hiroshi

2010-01-01

During the past two decades, amino acids and amino-acid derivatives have been applied in various fields of protein chemistry. The potential use of amino acids and their derivatives as new precipitating agents is described. Several amino acids and their derivatives are prominent additives in the field of protein chemistry. This study reports the use of charged amino acids and glycine ethyl ester as precipitants in protein crystallization, using hen egg-white lysozyme (HEWL) as a model. A discussion of the crystallization of HEWL using these reagents as precipitating agents is given

Chemical Characteristics of Precipitation in a Typical Urban Site of the Hinterland in Three Gorges Reservoir, China

Directory of Open Access Journals (Sweden)

Liuyi Zhang

2018-01-01

Full Text Available Major water-soluble ions were analyzed for two-year precipitation samples in Wanzhou, a typical urban site of the hinterland of Chinese Three Gorges Reservoir. The pH values of the precipitation were in the range of 4.0 to 8.3, and the volume-weighted mean (VWM value was 5.0. The concentration order of anions and cations was as follows: SO42->NO3->Cl->F- and NH4+>Ca2+>Na+>K+>Mg2+, respectively. Good correlations were found between SO42- and NH4+, SO42- and Ca2+, NO3- and NH4+, and NO3- and Ca2+, implying their co-occurrence in the precipitation, most likely as (NH42SO4, (NH4HSO4, NH4NO3, CaSO4, and Ca(NO32. The sum of all measured ions was 416.4 μeq L−1, indicating serious air pollution in Wanzhou. NH4+ and Ca2+ were the most important ions neutralizing the acidic compounds in the precipitation; their major sources included agricultural activity and crustal dust. Local anthropogenic activities, for example, coal burning and traffic related sources, contributed most of SO42- and NO3-. The equivalent concentration ratio of SO42-/NO3- was 4.5, indicating that excessive emission of sulfur was the main reason leading to the precipitation acidity in Wanzhou. However, this ratio was lower than the ratio (5.9 in 2000s in Wanzhou, indicating that the contribution of nitric acid to the acidity of precipitation was strengthening.

Expanding atmospheric acid deposition in China from the 1990s to the 2010s

Science.gov (United States)

Yu, Haili; Wang, Qiufeng

2017-04-01

Atmospheric acid deposition is considered a global environmental issue. China has been experiencing serious acid deposition, which is anticipated to be more serious with the country's economic development and increasing consumption of fossil fuels in recent decades. By collecting nationwide data on pH and concentrations of sulfate (SO42-) and nitrate (NO3-) in precipitation between 1980 and 2014 in China, we explored the spatiotemporal variations of precipitation acid deposition (bulk deposition) and their influencing factors. Our results showed that average precipitation pH values were 4.86 and 4.84 in the 1990s and 2010s, respectively. This suggests that precipitation acid deposition in China has not seriously changes. Average SO42- deposition declined from 30.73 to 28.61 kg S ha-1 yr-1 but average NO3- deposition increased from 4.02 to 6.79 kg N ha-1 yr-1. Specifically, the area of severe precipitation acid deposition in southern China has shrunk to some extent as a result of decreasing pollutant emissions, whereas the area of moderate precipitation acid deposition has expanded in northern China, associated with rapid industrial and transportation development. Significant positive correlations have been found between precipitation acid deposition, energy consumption, and rainfall. Our findings provide a comprehensive evaluation of the spatiotemporal dynamics of precipitation acid deposition in China over past three decades, and confirm the idea that strategies implemented to save energy and reduce pollutant emissions in China have been effective in alleviating precipitation acid deposition. These findings might be used to demonstrate how developing countries could achieve economic development and environmental protection through the implementation of advanced technologies to reduce pollutant emissions.

Characterisation of Suspension Precipitated Nanocrystalline Hydroxyapatite Powders

International Nuclear Information System (INIS)

Mallik, P K; Swain, P.K.; Patnaik, S.C

2016-01-01

Hydroxyapatite (HA) is a well-known biomaterial for coating on femoral implants, filling of dental cavity and scaffold for tissue replacement. Hydroxyapatite possess limited load bearing capacity due to their brittleness. In this paper, the synthesis of nanocrystalline hydroxyapatite powders was prepared by dissolving calcium oxide in phosphoric acid, followed by addition of ammonia liquor in a beaker. The prepared solution was stirred by using magnetic stirrer operated at temperature of 80°C for an hour. This leads to the formation of hydroxyapatite precipitate. The precipitate was dried in oven for overnight at 100°C. The dried agglomerated precipitate was calcined at 800°C in conventional furnace for an hour. The influence of calcium oxide concentration and pH on the resulting precipitates was studied using BET, XRD and SEM. As result, a well-defined sub-rounded morphology of powders size of ∼41 nm was obtained with a salt concentration of 0.02 M. Finally, it can be concluded that small changes in the reaction conditions led to large changes in final size, shape and degree of aggregation of the hydroxyapatite particles. (paper)

Synthesis of amorphous acid iron phosphate nanoparticles

International Nuclear Information System (INIS)

Palacios, E.; Leret, P.; Fernández, J. F.; Aza, A. H. De; Rodríguez, M. A.

2012-01-01

A simple method to precipitate nanoparticles of iron phosphate with acid character has been developed in which the control of pH allows to obtain amorphous nanoparticles. The acid aging of the precipitated amorphous nanoparticles favored the P–O bond strength that contributes to the surface reordering, the surface roughness and the increase of the phosphate acid character. The thermal behavior of the acid iron phosphate nanoparticles has been also studied and the phosphate polymerization at 400 °C produces strong compacts of amorphous nanoparticles with interconnected porosity.

On the Relation between Natural and Enforced Syneresis of Acidic Precipitated Silica

Directory of Open Access Journals (Sweden)

Sebastian Wilhelm

2014-11-01

Full Text Available Silica in industrial production processes is precipitated by mixing an acid and an inorganic precursor. In this aqueous solution, silica particles form due to a polymerization reaction and agglomeration and, finally, build a gel. Thereafter, the reaction continues, and the gel network shrinks with the expulsion of the enclosed pore liquid. This slow process is known as “natural syneresis” and strongly affects the product properties, such as the agglomerate size, specific surface or porosity of the silica produced. In order to investigate the influence of process parameters, such as temperature, pH or ionic strength, on the shrinkage in shorter time-scales, we propose an acceleration of this process and define it as “enforced syneresis”. The acceleration is performed by applying a mechanical external force to the gel by means of a plunger and measuring the shrinkage behavior under these conditions. Thereby, the conceptual idea is the prediction of the shrinkage due to natural syneresis based on the results of enforced syneresis. We are now able to predict the natural syneresis behavior from enforced syneresis data by the development of a correlative model. Using this prediction model, we can show the influence of temperature on the maximum shrinkage and on its rate in a significantly shorter time of about 12 h instead of several days.

Participation of the Pennsylvania State University in the MAP3S precipitation chemistry network

International Nuclear Information System (INIS)

Lamb, D.; de Pena, R.G.

1991-04-01

The Meteorology Department of the Pennsylvania State University collected precipitation in central Pennsylvania for more than 14 years on behalf of the Multistate Atmospheric Power Production Pollution Study (MAP3S). The MAP3S protocol, based on the sampling of precipitation from individual meteorological events over a long period of time, has allowed both for the development of a chemical climatology of precipitation in the eastern region of the United States and for a vastly improved understanding of the atmospheric processes responsible for wet acidic deposition. The precipitation chemistry data from the Penn State MAP3S site provide evidence of links to the anthropogenic emissions of sulfur dioxide and oxidant precursors. There is now little doubt that the free acidity in the precipitation of the region is due to the presence of unneutralized sulfate in the aqueous phase. In the absence of significant sources of this sulfur species and in view of supplemental enrichment studies, it is concluded that the sulfate enters cloud and rain water primarily through the aqueous-phase oxidation of sulfur dioxide emitted into the air within the geographical region of deposition. Within the source region the local abundances of sulfur dioxide often exceed those of the oxidants, so the depositions of sulfate and free acidity tend to be modulated by the availability of the strong oxidants. As a consequence, the deposition of sulfate exhibits a very strong seasonal dependence and little response to changes in the emissions of sulfur dioxide

End point control of an actinide precipitation reactor

International Nuclear Information System (INIS)

Muske, K.R.

1997-01-01

The actinide precipitation reactors in the nuclear materials processing facility at Los Alamos National Laboratory are used to remove actinides and other heavy metals from the effluent streams generated during the purification of plutonium. These effluent streams consist of hydrochloric acid solutions, ranging from one to five molar in concentration, in which actinides and other metals are dissolved. The actinides present are plutonium and americium. Typical actinide loadings range from one to five grams per liter. The most prevalent heavy metals are iron, chromium, and nickel that are due to stainless steel. Removal of these metals from solution is accomplished by hydroxide precipitation during the neutralization of the effluent. An end point control algorithm for the semi-batch actinide precipitation reactors at Los Alamos National Laboratory is described. The algorithm is based on an equilibrium solubility model of the chemical species in solution. This model is used to predict the amount of base hydroxide necessary to reach the end point of the actinide precipitation reaction. The model parameters are updated by on-line pH measurements

Generation of dose-response relationships to assess the effects of acidity in precipitation on growth and productivity of vegetation

International Nuclear Information System (INIS)

Evans, L.S.

1981-01-01

Experiments were performed with several plant species in natural environments as well in a greenhouse and/or tissue culture facilities to establish dose-response functions of plant responses to simulated acidic rain in order to determine environmental risk assessments to ambient levels of acidic rain. Response functions of foliar injury, biomass of leaves and seed of soybean and pinto beans, root yields of radishes and garden beets, and reproduction of bracken fern are considered. The dose-response function of soybean seed yields with the hydrogen ion concentration of simulated acidic rainfalls was expressed by the equation y = 21.06-1.01 log x where y = seed yield in grams per plant and x = the hydrogen concentration if μeq l -1 . The correlation coefficient of this relationship was -0.90. A similar dose-response function was generated for percent fertilization of ferns in a forest understory. When percent fertilization is plotted on logarithmic scale with hydrogen ion concentration of the simulated rain solution, the Y intercept is 51.18, slope -0.041 with a correlation coefficient of -0.98. Other dose-response functions were generated that assist in a general knowledge as to which plant species and which physiological processes are most impacted by acidic precipitation. Some responses did not produce convenient dose-response relationships. In such cases the responses may be altered by other environmental factors or there may be no differences among treatment means

Precipitation and measurements of precipitation

NARCIS (Netherlands)

Schmidt, F.H.; Bruin, H.A.R. de; Attmannspacher, W.; Harrold, T.W.; Kraijenhoff van de Leur, D.A.

1977-01-01

In Western Europe, precipitation is normal phenomenon; it is of importance to all aspects of society, particularly to agriculture, in cattle breeding and, of course, it is a subject of hydrological research. Precipitation is an essential part in the hydrological cycle. How disastrous local

Forecasting gastrointestinal precipitation and oral pharmacokinetics of dantrolene in dogs using an in vitro precipitation testing coupled with in silico modeling and simulation.

Science.gov (United States)

Kambayashi, Atsushi; Dressman, Jennifer B

2017-10-01

The aim of the current research was to determine the precipitation kinetics of dantrolene sodium using canine biorelevant in vitro testing and to model the precipitation kinetics by appropriately coupling the data with an in silico tool adapted for dogs. The precipitation profiles of dantrolene sodium solutions were obtained with the in vitro paddle apparatus at a revolution rate of 50rpm. The in silico prediction tool was designed using STELLA software and the predicted plasma concentration profiles of dantrolene using the in vitro precipitation data were compared with the observed in vivo pharmacokinetics in beagle dogs. The plasma profiles of dantrolene, which served as a model weakly acidic drug which precipitates in the upper gastrointestinal tract, was successfully predicted using the in vitro precipitation testing coupled with the in silico modeling and simulation approach. The approach was subsequently used to forecast the effect of pharmaceutical excipients (HPMC/PG) on the ability of the drug to supersaturate in the gut and the resulting pharmacokinetics. The agreement of the simulated pharmacokinetics with the observed values confirms the ability of canine biorelevant media to predict oral performance of enhanced dosage forms in dogs. Copyright © 2017 Elsevier B.V. All rights reserved.

Aquatic chemistry of acid deposition

Energy Technology Data Exchange (ETDEWEB)

Stumm, W; Sigg, L; Schnoor, J L

1987-01-01

The occurrence of acid precipitation in many regions of the Northern hemisphere is a consequnece of human interference in the cycles that unite land, water and atmosphere. The oxidation of carbon, sulfur and nitrogen, resulting mostly from fossil fuel burning, rivals oxidation processes induced by photosynthesis and respiration and disturbs redox conditions in the atmosphere. The paper discusses oxidation-reduction reactions, particularly those involving atmospheric pollutants that are important in the formation of acid precipitation. Topics covered are: a stoichiometric model of acid rain formation; sulfur dioxide and ammonia adsorption; acid neutralizing capacity. The paper concludes that explanations of simple chemical equilibria between gases and water aid our understanding of how acidifying gases become dissolved in cloud water, in droplets of falling rain, or in fog. Rigorous definitions of base- or acid-neutralizing capacities are prerequisites to measuring and interpreting residual acidity in dry and wet deposition and for assessing the disturbance caused by the transfer of acid to terrestrial and aquatic ecosystems. 20 references.

Growth response of four species of Eastern hardwood tree seedlings exposed to ozone, acidic precipitation, and sulfur dioxide

International Nuclear Information System (INIS)

Davis, D.D. Skelly, J.M.

1992-01-01

In 1987 a study was conducted in controlled environment chambers to determine the foliar sensitivity of tree seedlings of eight species to ozone and acidic precipitation, and to determine the influence of leaf position on symptom severity. Jensen and Dochinger conducted concurrent similar studies in Continuously Stirred Tank Reactor (CSTR) chambers with ten species of forest trees. Based on the results of these initial studies, four species representing a range in foliar sensitivity to ozone were chosen: black cherry (Prunus serotina Ehrh.), red maple (Acer rubrum L.), northern red oak (Quercus rubra L.) and yellow-poplar (Liriodendron tulipifera L.). These species were also chosen because of their ecological and/or commercial importance in Pennsylvania. Seedlings were exposed in growth chambers simulated acid rain. In addition acute exposures to sulfur dioxide were conducted in a regime based on unpublished monitoring data collected near coal-fired power plants. The objective of this study was to determine if the pollutant treatments influenced the growth and productivity of seedlings of these four species. This information will help researchers and foresters understand the role of air pollution in productivity of eastern forests

The precipitation of double fluoride salts of uranium

Energy Technology Data Exchange (ETDEWEB)

Muir, C. W.A.

1963-02-15

Bench-scale kinetic tests were conducted to study the reduction and precipitation reactions involved in the preparation of ammonium uranous fluoride from high-purity uranyl nitrate solutions. Sulphur dioxide and formic acid were used to form the active reducing agent, nascent hyposulphite ion. The reduction was affected in the presence of ammonium fluoride, resulting in the precipitation of the highly insoluble double salt. It was found that uranium was precipituted at a constant rate throughout the progress of the reaction. It is postulated that the reducing agent was continuously regenerated, and that this reaction was rate controlling. As a result of this study, a reaction mechanism is proposed. (auth)

Extraction of rare earth elements from low-grade Bauxite via precipitation reaction

Science.gov (United States)

Kusrini, E.; Nurani, Y.; Bahari, ZJ

2018-03-01

The aim of this research was to determine the optimum hydrometallurgical parameters to extract the rare earth elements (REE) from low-grade bauxite through acid leaching and precipitation reaction. REE or lanthanide recovery by a precipitation method with sodium sulphate and sodium phosphate as precipitation agents is reported where the effect of pH and recovery of REE are described. The metal composition of REE in low-grade bauxite after treatment were analyzed by ICP-OES. The total recovery values of REE elements at the first precipitation reaction using sodium sulphate as the precipitation agent at pH 3.5 showed ~68.2% of lanthanum, ~18.9% cerium, and ~7.8% yttrium. Lanthanum was the rare-earth element present at the highest concentration in the low-grade bauxite after the series treatments. An optimum pH of 3.5 for precipitation of rare-earth elements using sodium sulphate was demonstrated where this method is recommended for the extraction of REE elements from low-grade bauxite.

Microbially-Mediated Precipitation of Calcium Carbonate Nanoparticles.

Science.gov (United States)

Kang, Ser Ku; Roh, Yul

2016-02-01

The objective of this study was to investigate the biomineralization of carbonate minerals using microorganisms (Wu Do-1) enriched from rhodoliths. A 16S rRNA sequence analysis showed that Wu Do-1 mainly contained Proteus mirabilis. The pH decreased from 6.5 to 5.3 over the first 4 days of incubation due to microbial oxidation of organic acids, after which it increased to 7.8 over the remaining incubation period. XRD analysis showed that the precipitates were Mg-rich cal- cite (MgxCa(1-x)CO3), whereas no precipitates were formed without the addition of Wu Do-1 in D-1 medium. SEM-EDS analyses showed that the Mg-rich calcite had a rhombohedron shape and consisted of Ca, Si and Mg with an extracelluar polymeric substance (EPS). In addition, TEM-EDS analyses revealed they were hexagon in shape, 500-700 nm in size, and composed of Ca, Mg, C, and O. These results indicated that Wu Do-1 induced precipitation of Mg-rich calcite on the cell walls and EPS via the accumulation of Ca and/or Mg ions. Therefore, microbial precipitation of carbonate nanoparticles may play an important role in metal and carbon biogeochemistry, as well as in carbon sequestration in natural environments.

The Contribution of Extreme Precipitation to the Total Precipitation in China

Institute of Scientific and Technical Information of China (English)

SUN Jian-Qi

2012-01-01

Using daily precipitation data from weather stations in China, the variations in the contribution of extreme precipitation to the total precipitation are analyzed. It is found that extreme precipitation accounts for approximately one third of the total precipitation based on the overall mean for China. Over the past half century, extreme precipitation has played a dominant role in the year-to-year variability of the total precipitation. On the decadal time scale, the extreme precipitation makes different contributions to the wetting and drying regions of China. The wetting trends of particular regions are mainly attributed to increases in extreme precipitation; in contrast, the drying trends of other regions are mainly due to decreases in non-extreme precipitation.

FIA-FAAS method for tannin determination based on a precipitation reaction with hemoglobin

Directory of Open Access Journals (Sweden)

Ferreira Edilene C.

2003-01-01

Full Text Available A flow system, coupled with flame atomic absorption spectrometry (FIA-FAAS, was developed for tannin determination in pigeon pea samples, exploring the precipitation reaction between tannins and proteins. Sample extracts obtained by sonication with a 50% (v/v methanol solution were introduced into the system and induced to react with a hemoglobin solution. The precipitate produced was retained on a filter located in the analytical flow. A reversed flow of 1% (w/v sodium dodecyl sulfate solution was used for solubilization of the precipitate from the filter and to conduct the tannin-hemoglobin complex to the FAAS, to quantify the iron ions present in the hemoglobin structure. A tannic acid solution was used to prepare the analytical curve. The proposed method allowed determination of 30 samples per hour, a standard deviation of 9.7% (n=10, and a quantification limit of 0.27 mg L-1 for tannic acid.

Fundamental chemistry of precipitation and mineral scale formation

Science.gov (United States)

Alan W. Rudie; Peter W. Hart

2005-01-01

The mineral scale that deposits in digesters and bleach plants is formed by a chemical precipitation process. As such, it is accurately described or modeled using the solubility product equilibrium constant. Although solubility product identifies the primary conditions that need to be met for a scale problem to exist, the acid base equilibria of the scaling anions...

Comparison and trend study on acidity and acidic buffering capacity of particulate matter in China

Science.gov (United States)

Ren, Lihong; Wang, Wei; Wang, Qingyue; Yang, XiaoYang; Tang, Dagang

2011-12-01

The acidity of about 2000 particulate matter samples from aircraft and ground-based monitoring is analyzed by the method similar to soil acidity determination. The ground-based samples were collected at about 50 urban or background sites in northern and southern China. Moreover, the acidic buffering capacity of those samples is also analyzed by the method of micro acid-base titration. Results indicate that the acidity level is lower in most northern areas than those in the south, and the acidic buffering capacity showed inverse tendency, correspondingly. This is the most important reason why the pollution of acidic-precipitation is much more serious in Southern China than that in Northern China. The acidity increases and the acidic buffering capacity drops with the decreasing of the particle sizes, indicating that fine particle is the main influencing factor of the acidification. The ionic results show that Ca salt is the main alkaline substance in particulate matter, whereas the acidification of particulate matter is due to the SO 2 and NO x emitted from the fossil fuel burning. And among of them, coal burning is the main contributor of SO 2, however the contribution of NO x that emitted from fuel burning of motor vehicles has increased in recent years. By comparison of the experimental results during the past 20 years, it can be concluded that the acid precipitation of particulate matter has not been well controlled, and it even shows an increasing tendency in China lately. The acid precipitation of particulate matter has begun to frequently attack in part of the northern areas. Multiple regression analysis indicates that coefficient value of the ions is the lowest at the urban sites and the highest at the regional sites, whereas the aircraft measurement results are intermediate between those two kinds of sites.

[Current situation and impact factors of acid deposition in main cites of Shandong Province].

Science.gov (United States)

Jia, Hong-yu; Zhang, Qiao-xian; Deng, Hong-bing; Zhao, Jing-zhu; Mu, Jin-bo; Zhang, De-zhi

2006-12-01

Based on the monitoring data for years in Shandong Province, current situation of acid rain in every city was assessed, and the temporal distribution of the dry, wet and total sulfur deposition in Jinan and Qingdao were studied. The results showed that Qingdao which had the largest precipitation acidity was the single city whose annul average precipitation pH was below 5. 60. The precipitation acidities in the main cities of Shandong Province were in a descent tendency. The total sulfur desposition in Jinan and Qingdao was basically stable or in a descent tendency, but also reached 10 t/(km(2)x a) or so. Among the total sulfur deposition flux, the dry deposition of sulfur had the greater contribution, and the contribution of SO2 dry deposition was higher than that of SO42- dry deposition. By analyzing the relation between the precipitation acidity and the SO2 discharge intensity, soil acidity and meteorological condition, the impact factors of acid precipitation in the cities of Shandong Province were revealed.

Acid rain information book. Second edition

International Nuclear Information System (INIS)

1983-05-01

Potential consequences of widespread acid precipitation are reviewed through an extensive literature search. Major aspects of the acid rain phenomena are discussed, areas of uncertainty identified, and current research summarized

Salts-based size-selective precipitation: toward mass precipitation of aqueous nanoparticles.

Science.gov (United States)

Wang, Chun-Lei; Fang, Min; Xu, Shu-Hong; Cui, Yi-Ping

2010-01-19

Purification is a necessary step before the application of nanocrystals (NCs), since the excess matter in nanoparticles solution usually causes a disadvantage to their subsequent coupling or assembling with other materials. In this work, a novel salts-based precipitation technique is originally developed for the precipitation and size-selective precipitation of aqueous NCs. Simply by addition of salts, NCs can be precipitated from the solution. After decantation of the supernatant solution, the precipitates can be dispersed in water again. By means of adjusting the addition amount of salt, size-selective precipitation of aqueous NCs can be achieved. Namely, the NCs with large size are precipitated preferentially, leaving small NCs in solution. Compared with the traditional nonsolvents-based precipitation technique, the current one is simpler and more rapid due to the avoidance of condensation and heating manipulations used in the traditional precipitation process. Moreover, the salts-based precipitation technique was generally available for the precipitation of aqueous nanoparticles, no matter if there were semiconductor NCs or metal nanoparticles. Simultaneously, the cost of the current method is also much lower than that of the traditional nonsolvents-based precipitation technique, making it applicable for mass purification of aqueous NCs.

The Fractionation and Enrichment of La Content by Precipitation

International Nuclear Information System (INIS)

Suyanti; Purwani, MV

2007-01-01

The fractionation and enrichment of La content by precipitation have been done. The feed was La hydroxide by product of monazite sand. La hydroxide was diluted in HNO 3 and was precipitated with ammonia. For to obtain La, diluent was precipitated at pH 8 and the filtrate was precipitated with oxalic acid. The precipitant of La concentrated was more rich than the feed. This process was done continue and fractionally. The best yield of enrichment of La was obtained at dilution of 25 gram La Hydroxide in 20 ml HNO 3 . The efficient degree of fractionation was XV. The average weight of La concentrate was obtained at every fraction was 1 gram. The total sum weight from fraction I until fraction XV 13.5 grams. The average of La content was 48%, average fractionation efficiency of La for every step of fractionation was 48 %. Total efficiency all process was 100%. The average ratio of La/Nd was 2 and the ratio of La/Ce almost infinite. Before processed La/Ce was 7.86, and after process increase to 26.92 - to approach ∞. Before processed ratio of La/Nd was 2.79, after processed increased to 4.4 - to approach ∞. (author)

Particle precipitation in connection with KOH etching of silicon

DEFF Research Database (Denmark)

Nielsen, Christian Bergenstof; Christensen, Carsten; Pedersen, Casper

2004-01-01

This paper considers the precipitation of iron oxide particles in connection with the KOH etching of cavities in silicon wafers. The findings presented in this paper suggest that the source to the particles is the KOH pellets used for making the etching solution. Experiments show that the precipi......This paper considers the precipitation of iron oxide particles in connection with the KOH etching of cavities in silicon wafers. The findings presented in this paper suggest that the source to the particles is the KOH pellets used for making the etching solution. Experiments show...... that the precipitation is independent of KOH etching time, but that the amount of deposited material varies with dopant type and dopant concentration. The experiments also suggest that the precipitation occurs when the silicon wafers are removed from the KOH etching solution and not during the etching procedure. When...... not removed, the iron oxide particles cause etch pits on the Si surface when later processed and exposed to phosphoric acid. It has been found that the particles can be removed in an HCl solution, but not completely in an H2SO4- H2O2 solution. The paper discusses the involved precipitation mechanism in terms...

The Global Precipitation Climatology Project (GPCP) Combined Precipitation Dataset

Science.gov (United States)

Huffman, George J.; Adler, Robert F.; Arkin, Philip; Chang, Alfred; Ferraro, Ralph; Gruber, Arnold; Janowiak, John; McNab, Alan; Rudolf, Bruno; Schneider, Udo

1997-01-01

The Global Precipitation Climatology Project (GPCP) has released the GPCP Version 1 Combined Precipitation Data Set, a global, monthly precipitation dataset covering the period July 1987 through December 1995. The primary product in the dataset is a merged analysis incorporating precipitation estimates from low-orbit-satellite microwave data, geosynchronous-orbit -satellite infrared data, and rain gauge observations. The dataset also contains the individual input fields, a combination of the microwave and infrared satellite estimates, and error estimates for each field. The data are provided on 2.5 deg x 2.5 deg latitude-longitude global grids. Preliminary analyses show general agreement with prior studies of global precipitation and extends prior studies of El Nino-Southern Oscillation precipitation patterns. At the regional scale there are systematic differences with standard climatologies.

A simple and effective method for detecting precipitated proteins in MALDI-TOF MS.

Science.gov (United States)

Oshikane, Hiroyuki; Watabe, Masahiko; Nakaki, Toshio

2018-04-01

MALDI-TOF MS has developed rapidly into an essential analytical tool for the life sciences. Cinnamic acid derivatives are generally employed in routine molecular weight determinations of intact proteins using MALDI-TOF MS. However, a protein of interest may precipitate when mixed with matrix solution, perhaps preventing MS detection. We herein provide a simple approach to enable the MS detection of such precipitated protein species by means of a "direct deposition method" -- loading the precipitant directly onto the sample plate. It is thus expected to improve routine MS analysis of intact proteins. Copyright © 2018. Published by Elsevier Inc.

2,3-Butanediol recovery from fermentation broth by alcohol precipitation and vacuum distillation.

Science.gov (United States)

Jeon, Sangjun; Kim, Duk-Ki; Song, Hyohak; Lee, Hee Jong; Park, Sunghoon; Seung, Doyoung; Chang, Yong Keun

2014-04-01

This study presents a new and effective downstream process to recover 2,3-butanediol (2,3-BD) from fermentation broth which is produced by a recombinant Klebsiella pneumoniae strain. The ldhA-deficient K. pneumoniae strain yielded about 90 g/L of 2,3-BD, along with a number of by-products, such as organic acids and alcohols, in a 65 h fed-batch fermentation. The pH-adjusted cell-free fermentation broth was firstly concentrated until 2,3-BD reached around 500 g/L by vacuum evaporation at 50°C and 50 mbar vacuum pressure. The concentrated solution was further treated using light alcohols, including methanol, ethanol, and isopropanol, for the precipitation of organic acids and inorganic salts. Isopropanol showed the highest removal efficiency, in which 92.5% and 99.8% of organic acids and inorganic salts were precipitated, respectively. At a final step, a vacuum distillation process enabled the recovery of 76.2% of the treated 2,3-BD, with 96.1% purity, indicating that fermentatively produced 2,3-BD is effectively recovered by a simple alcohol precipitation and vacuum distillation. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

A study of selective precipitation techniques used to recover refined iron oxide pigments for the production of paint from a synthetic acid mine drainage solution

International Nuclear Information System (INIS)

Ryan, M.J.; Kney, A.D.; Carley, T.L.

2017-01-01

New resource recovery methods of acid mine drainage (AMD) treatment aim to reduce waste by extracting iron contaminants in usable forms, specifically iron oxides as industrial inorganic pigments, which can be marketed and sold to subsidize treatment costs. In this study, iron oxide pigments of varying colors and properties were recovered from a synthetic AMD solution through a stepwise selective precipitation process using oxidation, pH adjustment, and filtration. Chemical and physical design variables within the process, such as alkaline addition rate, reaction temperature, drying duration, and target pH, were altered and observed for their effects on iron oxide morphology as a means of reducing—or even eliminating—the need for refining after synthesis. Resulting iron oxide pigment powders were analyzed with X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS), and visually evaluated for color and coating ability. Drying duration resulted in increased redness in paint streaks and enhanced crystallinity, as amorphous phases of iron oxide transformed into hematite. Alkaline addition rate showed no effect on the crystallinity of the powders and no consistent effect on color. Conversely, increasing reaction temperature darkened the color of pigments and increased surface area of pigment particles (thus improving coating ability) without changing the crystallinity of the samples. Iron oxides precipitated at pH 3 displayed the highest purity and possessed a distinct yellow color suggestive of jarosite, while other paint streaks darkened in color as trace metal impurities increased. The choice to use lower pH for higher quality iron oxides comes with the compromise of reduced iron recovery efficiency. Manganese and nickel did not begin to precipitate out of solution up to pH 7 and thus require increased pH neutralization in the field if natural AMD is found to contain those metals. All pigments developed in this study were found to be adequate for use as

Recovery of Am-Cm from high-activity waste concentrate by in-canyon-tank precipitation as oxalates

International Nuclear Information System (INIS)

Gray, L.W.; Burney, G.A.; Wilson, T.W.; McKibben, J.M.

1980-01-01

Savannah River Laboratory and Savannah River Plant have been separating actinides for more than 25 years. Work continues to upgrade processes and to initiate new processes. This report summarizes work on a precipitation process to separate kg amounts of Am and Cm from hundreds of kilograms of NaNO 3 and Al(NO 3 ) 3 . The developed process includes formic acid denitration of the Am-Cm bearing streams for acid adjustment; oxalate precipitation of the Am-Cm; and Mn +2 catalyzed oxidation of oxalate in both the decanted supernate and the precipitated actinides. The new process generates one fourth the radioactive waste as the solvent extraction process which it replaced, and produces a cleaner feed solution for downstream processing to separate the Am and Cm before conversion to their respective oxides

Removal of ammonia from landfill leachate by struvite precipitation with the use of low-cost phosphate and magnesium sources.

Science.gov (United States)

Huang, Haiming; Xiao, Dean; Zhang, Qingrui; Ding, Li

2014-12-01

This paper presents a study concerning ammonia removal from landfill leachate by struvite precipitation with the use of waste phosphoric acid as the phosphate source. The results indicated that the Al(3+) ions present in the waste phosphoric acid significantly affected the struvite precipitation, and a removal ratio of ammonia close to that of pure phosphate salts could be achieved. Nevertheless, large amounts of NaOH were necessary to neutralize the H(+) present in the waste phosphoric acid. To overcome this problem, a low-cost magnesium source was proposed to be used as well as an alkali reagent in the struvite precipitation. The ammonia removal ratios were found to be 83%, with a remaining phosphate of 56 mg/L, by dosing the low-cost MgO in the Mg:N:P molar ratio of 3:1:1. An economic analysis showed that using waste phosphoric acid plus the low-cost MgO could save chemical costs by 68% compared with the use of pure chemicals. Post-treatment employment of a biological anaerobic filter process demonstrated that the high concentration of Mg(2+) remaining in the effluent of the struvite precipitation has no inhibitory effect on the performance of the biological treatment. Copyright © 2014 Elsevier Ltd. All rights reserved.

PREPARATION OF METAL OXIDE POWDERS FROM METAL LOADED VERSATIC ACID

OpenAIRE

KAKIHATA, Takayuki; USAMI, Kensuke; YAMAMOTO, Hideki; SHIBATA, Junji

1998-01-01

A production process for metal oxide powders was developed using a solvent extraction method. Versatic Acid 10 and D2EHPA solutions containing copper, zinc and nickel were used for a precipitation-stripping process, where oxalic acid was added to the solution as a precipitation reagent.Copper, zinc and nickel oxalates were easily formed in an aqueous phase, and 99.9% of precipitation was obtained for each metal during this process. These metal oxalates were easily converted to metal oxides by...

Separation and purification of uranium product from thorium in thorex process by precipitation technique

International Nuclear Information System (INIS)

Ramanujam, A.; Dhami, P.S.; Gopalakrishnan, V.; Mukherjee, A.; Dhumwad, R.K.

1989-01-01

A sequential precipitation technique is reported for the separation of uranium and thorium present in the uranium product stream of a single cycle 5 per cent TBP Thorex Process. It involves the precipitation of thorium as oxalate in 1M HNO 3 medium at 60-70degC and after filtration, precipitation of uranium as ammonium diuranate at 80-90degC from the oxalate supernatant. This technique has several advantages over the ion-exchange process normally used for treating these products. In order to meet the varying feed conditions, this method has been tested for feeds containing 10 g/1 uranium and 1-50 g/1 thorium in 1-6M HNO 3 . Various parameters like feed acidities, uranium and thorium concentrations, excess oxalic acid concentrations in the oxalate supernatant, precipitation temperatures, precipitate wash volumes etc. have been optimised to obtain more than 99 per cent recovery of thorium and uranium as their oxides with less than 50 ppm uranium losses to ammonium diuranate filtrate. The distribution patterns of different fission products and stainless steel corrosion products during various steps of this procedure have also been studied. For simulating the actual Thorex plant scale operation, experiments have been conducted with 25g and 100g lots of uranium per batch. (author). 6 tabs., 8 figs., 22 refs

On the Precipitation and Precipitation Change in Alaska

Directory of Open Access Journals (Sweden)

Gerd Wendler

2017-12-01

Full Text Available Alaska observes very large differences in precipitation throughout the state; southeast Alaska experiences consistently wet conditions, while northern Arctic Alaska observes very dry conditions. The maximum mean annual precipitation of 5727 mm is observed in the southeastern panhandle at Little Port Arthur, while the minimum of 92 mm occurs on the North Slope at Kuparuk. Besides explaining these large differences due to geographic and orographic location, we discuss the changes in precipitation with time. Analyzing the 18 first-order National Weather Service stations, we found that the total average precipitation in the state increased by 17% over the last 67 years. The observed changes in precipitation are furthermore discussed as a function of the observed temperature increase of 2.1 °C, the mean temperature change of the 18 stations over the same period. This observed warming of Alaska is about three times the magnitude of the mean global warming and allows the air to hold more water vapor. Furthermore, we discuss the effect of the Pacific Decadal Oscillation (PDO, which has a strong influence on both the temperature and precipitation in Alaska.

The characteristics changes of pH and EC of atmospheric precipitation and analysis on the source of acid rain in the source area of the Yangtze River from 2010 to 2015

Science.gov (United States)

Zong-Jie, Li; Song, Ling-Ling; Jing-zhu, Ma; Li, Yong-ge

2017-05-01

Through the analysis of pH value, EC, precipitation and wind speed of 402 precipitation samples in the source region of the Yangtze River from January 1, 2010 to December 31, 2015, especially for the analysis of the 14 acid rain events. The results showed that: the acid rain in the source region of the Yangtze River was mainly affected by the southwest monsoon and the westerly circulation. The occurrence of acid rain mainly controlled by industrial pollution and other pollutants coming from India and other surrounding areas. And the other cause was that because of the Qinghai Tibet highway and the Qinghai Tibet railway, there were a lot of cars coming and going. And there were people in the summer to plateau tourism increased year by year, and more for self-driving travelling. This added additional pollutants (automobile exhaust) for the source of the Yangtze River. During the period of sampling, the variation range of pH value was from 4.0 to 8.57, with the mean was 6.37. And the range of EC was from 5.2 to 124.4 μs/cm, the average was 27.59 μs/cm. The order of conductivity in the four seasons was Spring > Winter > Summer > Autumn. And the order of pH in four seasons was Summer > Spring = Winter > Autumn. The results are also helpful for further understanding the acid rain in the Tibetan Plateau and providing scientific basis for the effective prevention and control of acid rain.

Method for the recovery of uranium from a concentrate using pure phosphoric acid

International Nuclear Information System (INIS)

1980-01-01

Procedure for the recovery of an uranium bearing concentrate and pure phosphoric acid from a wet process phosphoric acid from the treatment fluid with a precipitation means in conjunction with an organic diluent, the thus formed precipitate to separate and from the remaining mixture of phosphoric acid and diluent the phosphoric acid to extract, characterised in that one applies an inorganic fluorine compound. (G.C.)

Biotic Iron Precipitation in Sand Filtration Systems by Gallionella ferruginea: Morphology and content of Exopolymers

DEFF Research Database (Denmark)

Søgaard, Erik Gydesen; Simonsen, Charlotte

conditions for principally biotic or abiotic iron precipitation is not well defined. An rH2 greater than 14 e.g. corresponding to an Eh a little above zero at slightly acidic pH is stated to be the best condition for biotic iron precipitation (Degremont, 1991). Abiotic iron precipitation is performed at a p...... are built with the purpose of biotic iron precipitation in order to reduce frequency of backwashing filtration systems. This is possibly due to the fact that biologically precipitated iron has a much denser structure than the corresponding abiotic precipitates (Søgaard et al. 2000). Both kinds of iron......-Peskir J. (2000) Conditions and rates of biotic and abiotic iron precipitation in selected Danish freshwater plants and microscopic analysis of precipitate morphology. Water Research, 34, 10, 2675-2682 Søgaard E.G., Aruna R., Abraham-Peskir, J. and Bender Koch, C. (2001) Conditions for iron precipitation...

Removal of arsenate by ferrihydrite via surface complexation and surface precipitation

Energy Technology Data Exchange (ETDEWEB)

Jiang, Xiuli [Department of Environment Engineering, College of the Environment and Ecology, and The Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystem, Xiamen University, Xiamen (China); Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, and The Key Laboratory for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen (China); Peng, Changjun; Fu, Dun; Chen, Zheng [Department of Environment Engineering, College of the Environment and Ecology, and The Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystem, Xiamen University, Xiamen (China); Shen, Liang [Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, and The Key Laboratory for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen (China); Li, Qingbiao [Department of Environment Engineering, College of the Environment and Ecology, and The Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystem, Xiamen University, Xiamen (China); Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, and The Key Laboratory for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen (China); Ouyang, Tong, E-mail: yz3t@xmu.edu.cn [Department of Environment Engineering, College of the Environment and Ecology, and The Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystem, Xiamen University, Xiamen (China); Wang, Yuanpeng, E-mail: wypp@xmu.edu.cn [Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, and The Key Laboratory for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen (China)

2015-10-30

Graphical abstract: - Highlights: • Surface complexation and surface precipitation of As on ferrihydrite happen at pH 3–6. • The formation of surface precipitation enhanced As(V) adsorption. • The dissolved Fe{sup 3+} had a good linear relationship with the amount of arsenate re-adsorption. - Abstract: In this study, macroscopic and spectroscopic experimental methods accurately modeled the sorption process of arsenate on ferrihydrite. EXAFS, X-ray diffraction and infrared (IR) spectroscopy indicated that the behavior of As(V) adsorption onto ferrihydrite took place mainly via surface complexation and surface precipitation at acidic pH (3.0–6.0), while the surface precipitation was dominated at longer time intervals and higher Fe{sup 3+} concentration. The macroscopic competitive adsorption experiment between arsenate with phosphate indicated two types of adsorption sites existing on the surface of ferrihydrite, i.e., non-exchangeable sites, which are responsible for a rapid surface complex formation; and exchangeable sites for a slow build-up of surface precipitates. In the slow build-up precipitates, the As(V) surface coverage (mmol/g) exhibited a good linear relationship (R{sup 2} = 0.952) with the amount of dissolved Fe{sup 3+}. Three steps are involved during the process of surface precipitation, i.e., (1) an initial uptake of As(V) via surface complexation; (2) re-adsorption of Fe{sup 3+} leaching from ferrihydrite on the surface complex; and (3) As(V) adsorption via surface complexation again and finally forming the surface precipitate.

Application of the Alternative Traditional and Selective Precipitation Routes for Recovery of High Grade Thorium Concentrates from Egyptian Crude Monazite Sand

International Nuclear Information System (INIS)

Helaly, O.S.

2017-01-01

Process flow sheet selection for thorium separation in relatively high grade concentrate from Egyptian crude monazite sand was carried out. Traditional selective leaching and precipitation routes were applied after sulfuric acid digestion upon Egyptian crude monazite for this purpose. The resultant hot grey sulfate paste from monazite digestion was firstly cooled to ambient temperature then leached by normal water into two successive stages. The first leach solution contained most of the thorium which represents about 88% of the present thorium and its concentration in the liquor reached 4.5 g Th/l. This liquor also contains most of the free acids and major of impurities especially iron (more than 6.3 g Fe/l). Different routes were tested to evaluate the suitable conditions that verify maximum recovery of thorium from such monazite sulfate solution and producing relatively high grade concentrate. Two different possible traditional and selective methods were involved, namely; thorium initial precipitation with rare earth elements as double sulfate or its precipitation as phosphate through acidity control at ph 1.1 which seems to be the simple, brief and convenient route to accomplish this purpose. Further separation and/or upgrading of thorium from these precipitates (after conversion to hydroxides or without) were conducted through re-dissolution in hydrochloric acid and re-precipitation with different selective reagents in the form of hydroxide, oxalate or fluoride was also included. The target was accomplished through thorium co-precipitation with light rare earth elements as double sulfate, followed by its recovery from this fraction, where a concentrate of grade 68.3% was produced

Synthesis of xenotime(YPO4) by precipitation from aqueous solution

International Nuclear Information System (INIS)

Hikichi, Yasuo; Hukuo, Ken-iti; Shiokawa, Jiro.

1978-01-01

Xenotime (tetragonal YPO 4 ) was synthesized by the precipitation from a mixed solution of yttrium chloride and orthophosphoric acid or orthophosphate above 50 0 C. At 50 0 C, the initial precipitate from the solutions in the pH range from 0.8 to 2.9 was crystalline weinschenkite (monoclinic YPO 4 .2H 2 O) and amorphous phosphate was formed at pH above 3, while precipitation did not take place at pH 0.5. Weinschenkite was stable at 50 0 C, but amorphous phosphate gradually crystallized by aging and became crystalline xenotime at pH 3.7 after 5 days and at pH 5.0 after 28 days. At 90 0 C, xenotime was detected in the precipitate from the solution of pH 0.5, and was also obtained by aging weinschenkite at pH between 0.8 and 2.9 or amorphous phosphate at pH above 3. The unit cell parameters of the synthesized xenotime were as follows: a=b=6.893A, c=6.026A. (auth.)

An alginate-antacid formulation localizes to the acid pocket to reduce acid reflux in patients with gastroesophageal reflux disease

NARCIS (Netherlands)

Rohof, Wout O.; Bennink, Roel J.; Smout, Andre J. P. M.; Thomas, Edward; Boeckxstaens, Guy E.

2013-01-01

Alginate rafts (polysaccharide polymers that precipitate into a low-density viscous gel when they contact gastric acid) have been reported to form at the acid pocket, an unbuffered pool of acid that floats on top of ingested food and causes postprandial acid reflux. We studied the location of an

The effect of a local source on the composition of precipitation in south-central Maine

Science.gov (United States)

Scott D. Boyce; Samuel S. Butcher

1976-01-01

Bulk precipitation samples were collected from ten sites in south-central Maine during the period 18 June to 30 September 1974. Data from the chemical analyses of the precipitation were used to determine regional deposition patterns of the ionic constituents. Acidic pH values ranging from 3.8 to 5.0 are characteristic of the region, but relatively alkaline pH values of...

Study of Ca-ATMP precipitation in the presence of magnesium ion.

Science.gov (United States)

Tantayakom, V; Fogler, H Scott; de Moraes, F F; Bualuang, M; Chavadej, S; Malakul, P

2004-03-16

ATMP (aminotri(methylenephosphonic acid)), a phosphonate scale inhibitor used in the petroleum industry, was used as a model scale inhibitor in this study. One of the goals of this work was to determine the range of conditions under which Mg ions, which are formed in reservoir formations containing dolomite, modulate the formation of Ca-ATMP precipitate as a scale inhibitor. The results revealed that the amount of ATMP precipitated decreased with addition of Mg ions in solution at all values of the solution pH. Furthermore, an increase in both the solution pH and the concentration of the divalent cations in solution resulted in a change of the molar ratio of (Ca + Mg) to ATMP in the precipitates. At a low solution pH (pH 1.5), Mg ions had little effect on the composition of the Ca-ATMP precipitate. However, at higher values of the solution pH (pH 4 and 7), the Ca to ATMP molar ratio in the precipitates decreased with increasing concentration of the Mg. Here it was found that Mg ions replaced Ca ions on available reactive sites of ATMP molecules. These results determined the limits of the Mg ion concentration, which affects the precipitation of Ca-ATMP, Mg-ATMP, and (Ca + Mg)-ATMP. The dissolution of the scale inhibitors was studied using a rotating disk reactor. These experiments showed that the total divalent cation molar ratio (Ca + Mg) to ATMP in the precipitates is the primary factor that controls the rate of dissolution (release) of the phosphonate precipitates. The phosphonate precipitate dissolution rates decreased as the molar ratio of divalent cations to ATMP in the precipitates increased.

Behavior of arsenic impurity at antimony electric precipitation

International Nuclear Information System (INIS)

Kim, G.N.; Rakhmanov, A.

2001-01-01

In the paper the arsenic impurity electrochemical behavior and it purification from antimony by electric precipitation out of fluoride solutions was studied. For this the arsenic sample with mass 0.003-0.006 g has been irradiated at the WWR-SM nuclear reactor during 3-5 hour in the thermal neutron flux 10 13 n/cm 2 s, after 24 h keeping the sample has being dissolved in the concentrated nitric acid, and then it has been evaporated several times with distillation water addition up to wet precipitation state. It is shown, that arsenic impurity behavior character in the antimony electric precipitation out to fluoride electrolyte depends on the electrolyte content, electrolysis conditions, arsenic valency state in arsenic impurity existence in the five-valency state its joint electric reduction with antimony is practically not observing. In the case the arsenic being in three-valency state, it joint electric reduction with antimony is taking place. In this time the electrolytic antimony contents arsenic impurities less in dozen time than initial material

Improvements on heap leaching process for a refractory uranium ore and yellow cake precipitation process

International Nuclear Information System (INIS)

Feng Jianke

2013-01-01

Some problems such as formed harden matrix, ore heap compaction, poor permeability, and agglomeration of absorption resin occur during extracting uranium from a refractory uranium ore by heap leaching process. After some measures were taken, i.e. spraying a new ore heap by low concentration acid, two or more ore heaps in series leaching, turning ores in ore heap, the permeability was improved, acid consumption was reduced. Through precipitate circulation and aging, the yellow cake slurry in amorphous or microlite form was transformed to crystal precipitate, thus uranium content in yellow cake was improved, and water content in yellow cake was lowered with good economic benefits. (author)

Chemical characteristics, deposition fluxes and source apportionment of precipitation components in the Jiaozhou Bay, North China

Science.gov (United States)

Xing, Jianwei; Song, Jinming; Yuan, Huamao; Li, Xuegang; Li, Ning; Duan, Liqin; Qu, Baoxiao; Wang, Qidong; Kang, Xuming

2017-07-01

To systematically illustrate the chemical characteristics, deposition fluxes and potential sources of the major components in precipitation, 49 rainwater and snow water samples were collected in the Jiaozhou Bay from June 2015 to May 2016. We determined the pH, electric conductivity (EC) and the concentrations of main ions (Na+, K+, Ca2 +, Mg2 +, NH4+, SO42 -, NO3-, Cl- and F-) as well as analyzed their source contributions and atmospheric transport. The results showed that the precipitation samples were severely acidified with an annual volume-weighted mean (VWM) pH of 4.77. The frequency of acid precipitation (pH pollution level over the Jiaozhou Bay. Surprisingly, NH4+ (40.4%), which is higher than Ca2 + (29.3%), is the dominant species of cations, which is different from that in most areas of China. SO42 - was the most abundant anions, and accounted for 41.6% of the total anions. The wet deposition fluxes of sulfur (S) was 12.98 kg ha- 1 yr- 1. Rainfall, emission intensity and long-range transport of natural and anthropogenic pollutants together control the concentrations and wet deposition fluxes of chemical components in the precipitation. Non-sea-salt SO42 - and NO3- were the primary acid components while NH4+ and non-sea-salt Ca2 + were the dominating neutralizing constituents. The comparatively lower rainwater concentration of Ca2 + in the Jiaozhou Bay than that in other regions in Northern China likely to be a cause for the strong acidity of precipitation. Based on the combined enrichment factor and correlation analysis, the integrated contributions of sea-salt, crustal and anthropogenic sources to the total ions of precipitation were estimated to be 28.7%, 14.5% and 56.8%, respectively. However, the marine source fraction of SO42 - may be underestimated as the contribution from marine phytoplankton was neglected. Therefore, the precipitation components in the Jiaozhou Bay present complex chemical characteristics under the combined effects of natural

Acidification of air and precipitation and its consequences on the natural environment

Energy Technology Data Exchange (ETDEWEB)

Oden, S

1968-01-01

Changes in the chemistry of the atmosphere were discussed using 15 years of data collected by a European sampling network, beginning in 1952. Sulfur content of air and precipitation were closely related to air pollution from cities and industry, as a result of increasing use of sulfurous fuels. A special study of the acidity of 600 lakes in western Scandinavia showed that between 1959 and 1967 pH values declined an average of 0.4 units. Acid precipitation will eventually acidify rivers. The change in pH will depend on the buffering capacity of the catchment area and other factors. Negative trends have already been noted. Acificiation threatens aquatic organisms as most cannot exist in water below pH 4.0. Certain valuable fish such as salmon are threatened at pH 5.5 and catches have begun to decline. Soils may also be affected if the supply of neutralizing substances declines. Decreased crop production and reduced forest growth rate may result. The balance of nature is disturbed by the present atmospheric pollution of sulfuric and other acids. (MDF)

Influence of phosphates when uranium in solutions obtained by attacking Forez with sulfuric acid is precipitated by the action of lime; Influence des phosphates, lors de la precipitation par la chaux, de l'uranium contenu dans les solutions d'attaque sulfurique du Forez

Energy Technology Data Exchange (ETDEWEB)

Brebec, G

1959-03-01

Influence of phosphates when uranium in solutions obtained by attacking Forez with sulfuric acid is precipitated by the action of lime was studied. Most of the phosphates were eliminated in the form of ferric phosphates without noticeable losses of uranium: for this it is only necessary to add sufficient ferric sulfate to the solution to be treated so that [Po{sub 4}{sup 3-}]/[Fe{sup 3+}] {approx} 0,4. In these conditions, the preparation of a calcium concentrate rich in uranium takes place in two stages. The first is neutralization at pH 2,7 to 2,8 with elimination of phosphates, sulfates and iron; the second is precipitation of the concentrate at pH 6,5. (author) [French] Nous avons reussi a eliminer la majeure partie des phosphates sous forme de phosphates ferriques, sans pertes sensibles d'uranium. Pour cela, il suffit d'ajouter a la solution a traiter, du sulfate ferrique en quantite telle que: (Po{sub 4}{sup 3-}]/[Fe{sup 3+}] {approx} 0,4. Dans ces conditions, la preparation du concentre calcique, riche en uranium, s'effectue normalement en deux temps: 1) preneutralisation a pH 2,7-2,8: elimination des sulfates, phosphates et fer; 2) precipitation du concentre a pH 6,5. (auteur)

Process for recovering a uranium containing concentrate and purified phosphoric acid from a wet process phosphoric acid containing uranium

International Nuclear Information System (INIS)

Weterings, C.A.M.; Janssen, J.A.

1985-01-01

A process is claimed for recovering from a wet process phosphoric acid which contains uranium, a uranium containing concentrate and a purified phosphoric acid. The wet process phosphoric acid is treated with a precipitant in the presence of a reducing agent and an aliphatic ketone

Process for recovering a uranium containing concentrate and purified phosphoric acid from a wet process phosphoric acid containing uranium

Energy Technology Data Exchange (ETDEWEB)

Weterings, C.A.M.; Janssen, J.A.

1985-04-30

A process is claimed for recovering from a wet process phosphoric acid which contains uranium, a uranium containing concentrate and a purified phosphoric acid. The wet process phosphoric acid is treated with a precipitant in the presence of a reducing agent and an aliphatic ketone.

The Role of Poly(Aspartic Acid) in the Precipitation of Calcium Phosphate in Confinement.

Science.gov (United States)

Cantaert, Bram; Beniash, Elia; Meldrum, Fiona C

2013-12-28

Many questions remain regarding the formation of ultrathin hydroxapatite (HAP) crystals within the confines of collagen fibrils of bones. These structures form through the interplay of the collagen matrix and non-collagenous proteins, and in vitro mineralization studies employing poly(aspartic acid) (PAsp) as a mimic of the non-collagenous proteins have generated mineralized fibrils with structures comparable to their biogenic counterparts. In this article, we employ the nanoscale cylindrical pores perforating track-etch filtration membranes to investigate the role of PAsp in controlling the infiltration and crystallization of calcium phosphate (CaP) within confined volumes. Oriented polycrystalline HAP and non-oriented octacalcium phosphate (OCP) rods precipitated within the membrane pores via an amorphous calcium phosphate (ACP) precursor, where PAsp increased the proportion of OCP rods. Further, ACP crystallized faster within the membranes than in bulk solution when PAsp was present, suggesting that PAsp inhibits crystallization in solution, but promotes it when bound to a substrate. Finally, in contrast to the collagen system, PAsp reduced the yield of intra-membrane mineral and failed to enhance infiltration. This suggests that a specific interaction between the collagen matrix and ACP/PAsp precursor particles drives effective infiltration. Thus, while orientation of HAP crystals can be achieved by confinement alone, the chemistry of the collagen matrix is necessary for efficient mineralisation with CaP.

Aerosol and precipitation chemistry in the southwestern United States: spatiotemporal trends and interrelationships

Science.gov (United States)

Sorooshian, A.; Shingler, T.; Harpold, A.; Feagles, C. W.; Meixner, T.; Brooks, P. D.

2013-08-01

This study characterizes the spatial and temporal patterns of aerosol and precipitation composition at six sites across the United States Southwest between 1995 and 2010. Precipitation accumulation occurs mostly during the wintertime (December-February) and during the monsoon season (July-September). Rain and snow pH levels are usually between 5-6, with crustal-derived species playing a major role in acid neutralization. These species (Ca2+, Mg2+, K+, Na+) exhibit their highest concentrations between March and June in both PM2.5 and precipitation due mostly to dust. Crustal-derived species concentrations in precipitation exhibit positive relationships with SO42-, NO3-, and Cl-, suggesting that acidic gases likely react with and partition to either crustal particles or hydrometeors enriched with crustal constituents. Concentrations of particulate SO42- show a statistically significant correlation with rain SO42- unlike snow SO42-, which may be related to some combination of the vertical distribution of SO42- (and precursors) and the varying degree to which SO42--enriched particles act as cloud condensation nuclei versus ice nuclei in the region. The coarse : fine aerosol mass ratio was correlated with crustal species concentrations in snow unlike rain, suggestive of a preferential role of coarse particles (mainly dust) as ice nuclei in the region. Precipitation NO3- : SO42- ratios exhibit the following features with potential explanations discussed: (i) they are higher in precipitation as compared to PM2.5; (ii) they exhibit the opposite annual cycle compared to particulate NO3- : SO42- ratios; and (iii) they are higher in snow relative to rain during the wintertime. Long-term trend analysis for the monsoon season shows that the NO3- : SO42- ratio in rain increased at the majority of sites due mostly to air pollution regulations of SO42- precursors.

Bio-precipitation of uranium by two bacterial isolates recovered from extreme environments as estimated by potentiometric titration, TEM and X-ray absorption spectroscopic analyses

Energy Technology Data Exchange (ETDEWEB)

Merroun, Mohamed L., E-mail: merroun@ugr.es [Institute of Radiochemistry, Helmholtz Centre Dresden-Rossendorf, Dresden (Germany); Departamento de Microbiologia, Universidad de Granada, Campus Fuentenueva s/n 18071, Granada (Spain); Nedelkova, Marta [Institute of Radiochemistry, Helmholtz Centre Dresden-Rossendorf, Dresden (Germany); Ojeda, Jesus J. [Cell-Mineral Interface Research Programme, Kroto Research Institute, University of Sheffield, Broad Lane, Sheffield S3 7HQ (United Kingdom); Experimental Techniques Centre, Brunel University, Uxbridge, Middlesex UB8 3PH (United Kingdom); Reitz, Thomas [Institute of Radiochemistry, Helmholtz Centre Dresden-Rossendorf, Dresden (Germany); Fernandez, Margarita Lopez; Arias, Jose M. [Departamento de Microbiologia, Universidad de Granada, Campus Fuentenueva s/n 18071, Granada (Spain); Romero-Gonzalez, Maria [Cell-Mineral Interface Research Programme, Kroto Research Institute, University of Sheffield, Broad Lane, Sheffield S3 7HQ (United Kingdom); Selenska-Pobell, Sonja [Institute of Radiochemistry, Helmholtz Centre Dresden-Rossendorf, Dresden (Germany)

2011-12-15

Highlights: Black-Right-Pointing-Pointer Precipitation of uranium as U phosphates by natural bacterial isolates. Black-Right-Pointing-Pointer The uranium biomineralization involves the activity of acidic phosphatase. Black-Right-Pointing-Pointer Uranium bioremediation could be achieved via the biomineralization of U(VI) in phosphate minerals. - Abstract: This work describes the mechanisms of uranium biomineralization at acidic conditions by Bacillus sphaericus JG-7B and Sphingomonas sp. S15-S1 both recovered from extreme environments. The U-bacterial interaction experiments were performed at low pH values (2.0-4.5) where the uranium aqueous speciation is dominated by highly mobile uranyl ions. X-ray absorption spectroscopy (XAS) showed that the cells of the studied strains precipitated uranium at pH 3.0 and 4.5 as a uranium phosphate mineral phase belonging to the meta-autunite group. Transmission electron microscopic (TEM) analyses showed strain-specific localization of the uranium precipitates. In the case of B. sphaericus JG-7B, the U(VI) precipitate was bound to the cell wall. Whereas for Sphingomonas sp. S15-S1, the U(VI) precipitates were observed both on the cell surface and intracellularly. The observed U(VI) biomineralization was associated with the activity of indigenous acid phosphatase detected at these pH values in the absence of an organic phosphate substrate. The biomineralization of uranium was not observed at pH 2.0, and U(VI) formed complexes with organophosphate ligands from the cells. This study increases the number of bacterial strains that have been demonstrated to precipitate uranium phosphates at acidic conditions via the activity of acid phosphatase.

Properties of Extreme Precipitation and Their Uncertainties in 3-year GPM Precipitation Radar Data

Science.gov (United States)

Liu, N.; Liu, C.

2017-12-01

Extreme high precipitation rates are often related to flash floods and have devastating impacts on human society and the environments. To better understand these rare events, 3-year Precipitation Features (PFs) are defined by grouping the contiguous areas with nonzero near-surface precipitation derived using Global Precipitation Measurement (GPM) Ku band Precipitation Radar (KuPR). The properties of PFs with extreme precipitation rates greater than 20, 50, 100 mm/hr, such as the geographical distribution, volumetric precipitation contribution, seasonal and diurnal variations, are examined. In addition to the large seasonal and regional variations, the rare extreme precipitation rates often have a larger contribution to the local total precipitation. Extreme precipitation rates occur more often over land than over ocean. The challenges in the retrieval of extreme precipitation might be from the attenuation correction and large uncertainties in the Z-R relationships from near-surface radar reflectivity to precipitation rates. These potential uncertainties are examined by using collocated ground based radar reflectivity and precipitation retrievals.

Dissolution and secondary mineral precipitation in basalts due to reactions with carbonic acid

Science.gov (United States)

Kanakiya, Shreya; Adam, Ludmila; Esteban, Lionel; Rowe, Michael C.; Shane, Phil

2017-06-01

One of the leading hydrothermal alteration processes in volcanic environments is when rock-forming minerals with high concentrations of iron, magnesium, and calcium react with CO2 and water to form carbonate minerals. This is used to the advantage of geologic sequestration of anthropogenic CO2. Here we experimentally investigate how mineral carbonation processes alter the rock microstructure due to CO2-water-rock interactions. In order to characterize these changes, CO2-water-rock alteration in Auckland Volcanic Field young basalts (less than 0.3 Ma) is studied before and after a 140 day reaction period. We investigate how whole core basalts with similar geochemistry but different porosity, permeability, pore geometry, and volcanic glass content alter due to CO2-water-rock reactions. Ankerite and aluminosilicate minerals precipitate as secondary phases in the pore space. However, rock dissolution mechanisms are found to dominate this secondary mineral precipitation resulting in an increase in porosity and decrease in rigidity of all samples. The basalt with the highest initial porosity and volcanic glass volume shows the most secondary mineral precipitation. At the same time, this sample exhibits the greatest increase in porosity and permeability, and a decrease in rock rigidity post reaction. For the measured samples, we observe a correlation between volcanic glass volume and rock porosity increase due to rock-fluid reactions. We believe this study can help understand the dynamic rock-fluid interactions when monitoring field scale CO2 sequestration projects in basalts.

Processes for working-up an aqueous fluosilicic acid solution

Directory of Open Access Journals (Sweden)

Alpha O. Toure

2012-11-01

Full Text Available Aqueous fluosilicic acid solutions were once considered to be only adverse by-products of phosphoric acid production, which required treatment to prevent ecosystem destruction when discharged into the sea. However, a range of chemicals can be generated by the transformation of this industrial waste product. Through experiments undertaken in the laboratory, we have shown the possibility of caustic soda production. Volumetric analysis showed caustic soda to be present as a 6%– 7%solution with yields of about 70% – 80%by weight. Two processes were investigated for the caustification of sodium fluoride, using different precipitates: sodium chloride and ethanol and are described by modelling caustification curves. The activation energies of precipitation determined by semi-empirical correlations showed that precipitation by ethanol (EA = 933.536 J/mol was more successful than precipitation by sodium chloride (EA = 7452.405 J/mol. Analyses performed on the precipitates highlighted compositions that are essential and useful constituents in the cement industry.

Biologically-induced precipitation of sphalerite-wurtzite nanoparticles by sulfate-reducing bacteria: implications for acid mine drainage treatment.

Science.gov (United States)

Castillo, Julio; Pérez-López, Rafael; Caraballo, Manuel A; Nieto, José M; Martins, Mónica; Costa, M Clara; Olías, Manuel; Cerón, Juan C; Tucoulou, Rémi

2012-04-15

Several experiments were conducted to evaluate zinc-tolerance of sulfate-reducing bacteria (SRB) obtained from three environmental samples, two inocula from sulfide-mining districts and another inoculum from a wastewater treatment plant. The populations of SRB resisted zinc concentrations of 260 mg/L for 42 days in a sulfate-rich medium. During the experiments, sulfate was reduced to sulfide and concentrations in solution decreased. Zinc concentrations also decreased from 260 mg/L to values below detection limit. Both decreases were consistent with the precipitation of newly-formed sphalerite and wurtzite, two polymorphs of ZnS, forming <2.5-μm-diameter spherical aggregates identified by microscopy and synchrotron-μ-XRD. Sulfate and zinc are present in high concentrations in acid mine drainage (AMD) even after passive treatments based on limestone dissolution. The implementation of a SRB-based zinc removal step in these systems could completely reduce the mobility of all metals, which would improve the quality of stream sediments, water and soils in AMD-affected landscapes. Copyright © 2012 Elsevier B.V. All rights reserved.

Development of atmospheric acid deposition in China from the 1990s to the 2010s

International Nuclear Information System (INIS)

Yu, Haili; He, Nianpeng; Wang, Qiufeng; Zhu, Jianxing; Gao, Yang; Zhang, Yunhai; Jia, Yanlong; Yu, Guirui

2017-01-01

Atmospheric acid deposition is a global environmental issue. China has been experiencing serious acid deposition, which is anticipated to become more severe with the country's economic development and increasing consumption of fossil fuels in recent decades. We explored the spatiotemporal variations of acid deposition (wet acid deposition) and its influencing factors by collecting nationwide data on pH and concentrations of sulfate (SO 4 2− ) and nitrate (NO 3 − ) in precipitation between 1980 and 2014 in China. Our results showed that average precipitation pH values were 4.59 and 4.70 in the 1990s and 2010s, respectively, suggesting that precipitation acid deposition in China has not seriously worsened. Average SO 4 2− deposition declined from 40.54 to 34.87 kg S ha −1 yr −1 but average NO 3 − deposition increased from 4.44 to 7.73 kg N ha −1 yr −1 . Specifically, the area of severe precipitation acid deposition in southern China has shrunk to some extent as a result of controlling the pollutant emissions; but the area of moderate precipitation acid deposition has expanded in northern China, associated with rapid industrial and transportation development. Furthermore, we found significant positive correlations between precipitation acid deposition, energy consumption, and rainfall. Our findings provide a relatively comprehensive evaluation of the spatiotemporal dynamics of precipitation acid deposition in China over past three decades, and confirm the idea that strategies implemented to save energy and control pollutant emissions in China have been effective in alleviating precipitation acid deposition. These findings might be used to demonstrate how developing countries could achieve economic development and environmental protection through the implementation of advanced technologies to reduce pollutant emissions. - Highlights: • Explore spatial and temporal dynamics of wet acid deposition during three decades in China. • Acid

Precipitation kinetics of a continuous precipitator, with application to the precipitation of ammonium polyuranate

International Nuclear Information System (INIS)

Hoyt, R.C.

1978-04-01

A mathematical model describing the kinetics of continuous precipitation was developed which accounts for crystal nucleation, crystal growth, primary coagulation, and secondary coagulation. Population density distributions, average particle sizes, dominant particle sizes, and suspension density fractions of the crystallites, primary agglomerates, and secondary agglomerates leaving the continuous precipitator can be determined. This kinetic model was applied to the continuous precipitation of ammonium polyuranate, which consists of: (1) elementary crystals, (2) clusters or primary coagulated particles, and (3) agglomerates or secondary coagulated particles. The crystallites are thin, submicron, hexagonal platelets. The clusters had an upper size limit of about 7 μ in diameter and contained numerous small voids (less than 0.3 μm) due to the packing of the crystallites. The agglomerates had an upper size limit of about 40 μm in diameter and contained large voids (approximately 1 μm). The particle size distribution and particle structure of the ammonium polyuranate precipitate can be controlled through proper regulation of the precipitation conditions. The ratio of clusters to agglomerates can be best controlled through the uranium concentration, and the cohesiveness or internal bonding strength of the particles can be controlled with the ammonium to uranium reacting feed mole ratio. These two conditions, in conjunction with the residence time, will determine the nucleation rates, growth rates, and size distributions of the particles leaving the continuous precipitator. With proper control of these physical particle characteristics, the use of pore formers, ball-milling, and powder blending can probably be eliminated from the nuclear fuel fabrication process, substantially reducing the cost

Precipitation kinetics of a continuous precipitator, with application to the precipitation of ammonium polyuranate

Energy Technology Data Exchange (ETDEWEB)

Hoyt, R.C.

1978-04-01

A mathematical model describing the kinetics of continuous precipitation was developed which accounts for crystal nucleation, crystal growth, primary coagulation, and secondary coagulation. Population density distributions, average particle sizes, dominant particle sizes, and suspension density fractions of the crystallites, primary agglomerates, and secondary agglomerates leaving the continuous precipitator can be determined. This kinetic model was applied to the continuous precipitation of ammonium polyuranate, which consists of: (1) elementary crystals, (2) clusters or primary coagulated particles, and (3) agglomerates or secondary coagulated particles. The crystallites are thin, submicron, hexagonal platelets. The clusters had an upper size limit of about 7 ..mu.. in diameter and contained numerous small voids (less than 0.3 ..mu..m) due to the packing of the crystallites. The agglomerates had an upper size limit of about 40 ..mu..m in diameter and contained large voids (approximately 1 ..mu..m). The particle size distribution and particle structure of the ammonium polyuranate precipitate can be controlled through proper regulation of the precipitation conditions. The ratio of clusters to agglomerates can be best controlled through the uranium concentration, and the cohesiveness or internal bonding strength of the particles can be controlled with the ammonium to uranium reacting feed mole ratio. These two conditions, in conjunction with the residence time, will determine the nucleation rates, growth rates, and size distributions of the particles leaving the continuous precipitator. With proper control of these physical particle characteristics, the use of pore formers, ball-milling, and powder blending can probably be eliminated from the nuclear fuel fabrication process, substantially reducing the cost.

Precipitation and purification of uranium from rock phosphate

International Nuclear Information System (INIS)

AbowSlama, E.H.Y.; Sam, A.K.; Etemad Ebraheem

2014-01-01

This study was carried-out to leach uranium from rock phosphate using sulphuric acid in the presence of potassium chlorate as an oxidant and to investigate the relative purity of different forms of yellow cakes produced with ammonia, magnesia and sodium hydroxide as precipitants, as well as purification of the products with TBP and matching its impurity levels with specifications of the commercial products. Alpha-particle spectrometry was used for determination of activity concentration of uranium isotopes in rock phosphate, resulting phosphoric acid, and in different forms of the yellow cake. Likewise, atomic absorption spectroscopy was used for determination of impurities. On the average, the equivalent mass concentration of uranium was 119.38 ± 79.66 ppm (rock phosphate) and 57.85 ± 20.46 ppm (phosphoric acid) with corresponding low percent of dissolution (48 %) which is considered low. The isotopic ratio ( 234 U: 238 U) in all stages of hydrometallurgical process was not much different from unity indicating lack of fractionation. Upon comparing the levels of impurities in different form of crude yellow cakes, it was found that the lowest levels were measured in hydrated trioxide (UO 3 ·xH 2 O). This implies that saturated magnesia is least aggressive relative to other precipitants and gives relatively pure crude cake. Therefore, it was used as an index to judge the relative purity of other forms of yellow cakes by taking the respective elemental ratios. The levels of impurities (Fe, Zn, Mn, Cu, Ni, Cd and Pb) in the purified yellow cake were found comparable with those specified for commercial products. (author)

Sintesa Precipitated Calcium Carbonate (PCC) dari Cangkang Kerang Darah (Anadara Granosa) dengan Variasi Ukuran Partikel dan Waktu Karbonasi

OpenAIRE

Rahmawati, Lucy; Amri, Amun; Zultiniar, Zultiniar; Yelmida, Yelmida

2015-01-01

Precipitated Calcium Carbonate (PCC) is a product of the processing of natural materials containing calcium carbonate resulting from the precipitation process with high purity. Bloodcockle shell can be used as a source of calcium for precipitated Calcium Carbonate. The purpose of this study to produce PCC of waste shells blood with carbonation method and determine the particle size of the PCC and the best carbonation time. Synthesis performed using carbonation method by adding nitric acid to ...

On basicity and composition of molybdogermanium heteropoly acid

International Nuclear Information System (INIS)

Mirzoyan, F.V.; Tarayan, V.M.; Petrosyam, A.A.

1984-01-01

The data on the number of single-charged cations of the basic dye (BD) associated by anion of molybdogermanium heteropoly acid equal to effective acid basicity, as well as the data on chemical analysis of formed solid-phase BD-MGA compounds were used to establish that composition and basicity of MGA depend on the nature of dye-precipitator. The use of acridine orange results in stabilization and precipitation of octasubstituted 12MGA salt, and acriflavine-tetrasubstituted 8MGA salt. Formation of the last ones is independent of medium acidity in its wide range: pH 0.45-4.80 and pH 0-3.8 respectively

Interaction of bovine gallbladder mucin and calcium-binding protein: effects on calcium phosphate precipitation.

Science.gov (United States)

Afdhal, N H; Ostrow, J D; Koehler, R; Niu, N; Groen, A K; Veis, A; Nunes, D P; Offner, G D

1995-11-01

Gallstones consist of calcium salts and cholesterol crystals, arrayed on a matrix of gallbladder mucin (GBM), and regulatory proteins like calcium-binding protein (CBP). To determine if interactions between CBP and GBM follow a biomineralization scheme, their mutual binding and effects on CaHPO4 precipitation were studied. Binding of CBP to GBM was assessed by inhibition of the fluorescence of the complex of GBM with bis-1,8-anilinonaphthalene sulfonic acid (bis-ANS). The effects of the proteins on precipitation of CaHPO4 were assessed by nephelometry and gravimetry. Precipitates were analyzed for calcium, phosphate, and protein. CBP and bis-ANS competitively displaced each other from 30 binding sites on mucin, with a 1:1 stoichiometry and similar affinity. The rate of precipitation of CaHPO4 was retarded by mucin and CBP. Precipitate mass was unaffected by GBM alone but decreased with the addition of CBP. Complexing CBP with GBM abolished or moderated this latter effect, altered precipitate morphology, and changed the stoichiometric ratios of Ca to PO4 in the precipitates from 1:1 to 3:2. Mucin and CBP were incorporated into the precipitates. These studies suggest that the formation of calcium-containing gallstones is a biomineralization process regulated by both GBM and CBP.

Micro-precipitation of Americium by Cerium Hydroxide for alpha spectrometry

International Nuclear Information System (INIS)

Wankhede, Sonal M.; Kumar, Suja A.; Sawant, Pramilla D.

2018-01-01

Estimation of trace amount of actinides in any biological and/or environmental sample is done by radiochemical separation followed by alpha spectrometry. Alpha-spectrometric determination of actinides requires thin, homogeneous and nearly weightless sample sources. The most widely used method for preparation of actinides for alpha spectrometry involves electro deposition of the alpha emitters using stainless steel planchetts (cathode) and platinum rod (anode). This procedure is time consuming, requires relatively elaborate equipment, and is expensive. Micro-precipitation technique using hydrofluoric acid (HF) is also reliable and already standardized at Bioassay Laboratory (Wankhede, 2016). However, it uses hazardous chemical such as HF, hence, in the present study, cerium hydroxide micro-precipitation technique was standardized

The Effect of Double Crosslinker on Precipitation Polymerization of Poly(acrylic acid

Directory of Open Access Journals (Sweden)

Hajar Es-haghi

2014-06-01

Full Text Available Cross-linked poly(acrylic acids were prepared by dual cross-linkers via precipitation polymerization method in a binary organic solvent. Polyethylene glycol diacrylate (PEGDA-400 as a long-chain cross-linker and di(trimethylol propane tetraacrylate (DTMPTA as multifunctional cross-linker were used. PEGDA-400 was utilized to increase thickening properties and DTMPTA was used to improve the gel strength. The dual cross-linkers effect on the sample features (i.e., equilibrium swelling, thickening properties and rheological properties was investigated. Maximum amount of swelling was obtained by a high percentage of long-chain cross-linker. The apparent viscosity of the microgels was measured to determine their thickening properties for aqueous media. Maximum viscosity occurred at DT25-PE75 which was dependent on the type of cross-linkers in the polymer structure. The Flory-Rehner equation (from swelling ratio data and rubber elasticity theory (from rheometry data were used to discuss the network structure of the polymer. Increasing density of the network was shown by a sample containing high percentage of a four-functional cross-linker. The rheological properties of the cross-linked polymers were measured to determine storage modulus (strength network. The rheological behaviors demonstrated that the synthesized polymer containing a high amount of four-functional cross-linker had higher storage modulus (G′ than other samples. In addition the consistency coefficient (m and flow behavior index (n parameters of Ostwald equation were investigated as well. As a result, n values in each sample were found to be smaller than 1 and these results were fitted clearly with the pseudoplastic model. Apparent and rotational viscosities were used to determine the optimal cross-linker type (synthesized sample contained a high percentage of long-chain cross-linker.

A rapid phospholipase D assay using zirconium precipitation of anionic substrate phospholipids

DEFF Research Database (Denmark)

Petersen, G.; Hansen, Harald S.; Chapman, K.D.

2000-01-01

-acylphosphatidylethanolamine (NAPE)-hydrolyzing PLD activity, which produces two lipophilic products, N-acylethanolamine (NAE) and phosphatidic acid. Therefore, we developed a rapid assay for the routine detection of NAPE-hydrolyzing PLD activity. This assay is based on precipitation of radiolabeled substrate (NAPE) in the presence...

Disentangling Seasonality and Mean Annual Precipitation in the Indo-Pacific Warm Pool: Insights from Coupled Plant Wax C and H Isotope Measurements

Science.gov (United States)

Galy, V.; Oppo, D.; Dubois, N.; Arbuszewski, J. A.; Mohtadi, M.; Schefuss, E.; Rosenthal, Y.; Linsley, B. K.

2016-12-01

There is ample evidence suggesting that rainfall distribution across the Indo-Pacific Warm Pool (IPWP) - a key component of the global climate system - has substantially varied over the last deglaciation. Yet, the precise nature of these hydroclimate changes remains to be elucidated. In particular, the relative importance of variations in precipitation seasonality versus annual precipitation amount is essentially unknown. Here we use a set of surface sediments from the IPWP covering a wide range of modern hydroclimate conditions to evaluate how plant wax stable isotope composition records rainfall distribution in the area. We focus on long chain fatty acids, which are exclusively produced by vascular plants living on nearby land and delivered to the ocean by rivers. We relate the C (δ13C) and H (δD) isotope composition of long chain fatty acids preserved in surface sediments to modern precipitation distribution and stable isotope composition in their respective source area. We show that: 1) δ13C values reflect vegetation distribution (in particular the relative abundance of C3 and C4 plants) and are primarily recording precipitation seasonality (Dubois et al., 2014) and, 2) once corrected for plant fractionation effects, δD values reflect the amount-weighted average stable isotope composition of precipitation and are primarily recording annual precipitation amounts. We propose that combining the C and H isotope composition of long chain fatty acids thus allows independent reconstructions of precipitation seasonality and annual amounts in the IPWP. The practical implications for reconstructing past hydroclimate in the IPWP will be discussed.

Trends in precipitation and streamwater chemistry in East Creek watershed in southwestern British Columbia, 1971–2008

Directory of Open Access Journals (Sweden)

Michael C. FELLER

2010-08-01

Full Text Available Bulk precipitation and streamwater in a small, undisturbed, forested watershed in southwestern British Columbia were sampled regularly and analyzed for dissolved chemical constituents from 1971 to 2008. Concentrations and fluxes of most chemicals in precipitation and streamwater have exhibited considerable yearly variation. Temporal trends, when they have occurred, have rarely been consistent for the entire 1972–2008 time period. Precipitation has exhibited a decline in electrical conductivity, a decline in NH4, inorganic-N, and total-N concentrations and fluxes since the 1980s, an increase in pH, a decline in acid H fluxes since ~1990, and a decrease in SO4 concentrations and fluxes from 1980 until the late 1990s. Streamwater has exhibited an increase in NO3 concentrations and fluxes until the late 1990s, an increase in pH and decrease in acid H fluxes since the early 1990s, a decrease in SO4 concentrations and fluxes from ~1980 until ~2000, and increases in Na and Cl concentrations and fluxes until ~2000. Critical precipitation SO4 and inorganic-N loads have probably been exceeded for most years. East Ck. watershed has continuously experienced net inflows of all forms of N and acid H, and net outflows of dissolved Si, Na, Mg, and Ca. Net inflows of inorganic forms of N and total-N have decreased since the early 1980s. Net acid H inflows have decreased since the early 1990s, while net Na and Cl outflows increased until ~2000. The contribution of nutrient cycling processes within the watershed to the changes is currently unknown.

Optimization Recovery of Yttrium Oxide in Precipitation, Extraction, and Stripping Process

Science.gov (United States)

Perwira, N. I.; Basuki, K. T.; Biyantoro, D.; Effendy, N.

2018-04-01

Yttrium oxide can be used as a dopant control rod of nuclear reactors in YSH material and superconductors. Yttrium oxide is obtained in the Xenotime mineral derived from byproduct of tin mining PT Timah Bangka which contain rare earth elements (REE) dominant Y, Dy, and Gd whose content respectively about 29.53%, 7.76%, and 2.58%. Both usage in the field of nuclear and non-nuclear science and technology is need to pure from the impurities. The presence of impurities in the yttrium oxide may affect the characteristic of the material and the efficiency of its use. Thus it needs to be separated by precipitation and extraction-stripping and calcination in the making of the oxide. However, to obtain higher levels of Yttrium oxide, it is necessary to determine the optimum conditions for its separation. The purpose of this research was to determine the optimum pH of precipitation, determine acid media and concentration optimum in extraction and stripping process and determine the efficiency of the separation of Y from REE concentrate. This research was conducted with pH variation in the precipitation process that pHs were 4 - 8, the difference of acid media for the extraction process, i.e., HNO3, HCl and H2SO4 with each concentration of 0,5 M; 1 M; 1,5 M; and 2 M and for stripping process were HNO3, HCl, and H2SO4 with each concentration of 1 M; 2M; and 3 M. Based on the result, the optimum pH of precipitation process was 6,5, the optimumacid media was HNO3 0,5 M, and for stripping process media was HNO3 3 M. The efficiency of precipitation process at pH 6,5 was 69,53 %, extraction process was 96.39% and stripping process was 4,50%. The separation process from precipitation to extraction had increased the purity and the highest efficiency recovery of Y was in the extraction process and obtained Y2O3 purer compared to the feed with the Y2O3 content of 92.87%.

Bio-precipitation of uranium by two bacterial isolates recovered from extreme environments as estimated by potentiometric titration, TEM and X-ray absorption spectroscopic analyses.

Science.gov (United States)

Merroun, Mohamed L; Nedelkova, Marta; Ojeda, Jesus J; Reitz, Thomas; Fernández, Margarita López; Arias, José M; Romero-González, María; Selenska-Pobell, Sonja

2011-12-15

This work describes the mechanisms of uranium biomineralization at acidic conditions by Bacillus sphaericus JG-7B and Sphingomonas sp. S15-S1 both recovered from extreme environments. The U-bacterial interaction experiments were performed at low pH values (2.0-4.5) where the uranium aqueous speciation is dominated by highly mobile uranyl ions. X-ray absorption spectroscopy (XAS) showed that the cells of the studied strains precipitated uranium at pH 3.0 and 4.5 as a uranium phosphate mineral phase belonging to the meta-autunite group. Transmission electron microscopic (TEM) analyses showed strain-specific localization of the uranium precipitates. In the case of B. sphaericus JG-7B, the U(VI) precipitate was bound to the cell wall. Whereas for Sphingomonas sp. S15-S1, the U(VI) precipitates were observed both on the cell surface and intracellularly. The observed U(VI) biomineralization was associated with the activity of indigenous acid phosphatase detected at these pH values in the absence of an organic phosphate substrate. The biomineralization of uranium was not observed at pH 2.0, and U(VI) formed complexes with organophosphate ligands from the cells. This study increases the number of bacterial strains that have been demonstrated to precipitate uranium phosphates at acidic conditions via the activity of acid phosphatase. Copyright © 2011 Elsevier B.V. All rights reserved.

Precipitation and growth of zinc sulfide nanoparticles in the presence of thiol-containing natural organic ligands.

Science.gov (United States)

Lau, Boris L T; Hsu-Kim, Heileen

2008-10-01

In sulfidic aquatic systems, metal sulfides can control the mobility and bioavailability of trace metal pollutants such as zinc, mercury, and silver. Nanoparticles of ZnS and other metal sulfides are known to exist in oxic and anoxic waters. However, the processes that lead to their persistence in the aquatic environment are relatively unknown. The objective of this study was to evaluate the importance of dissolved natural organics in stabilizing nanoparticulate ZnS that precipitates under environmentally relevant conditions. Precipitation and growth of ZnS particles were investigated in the presence of dissolved humic acid and low-molecular weight organic acids that are prevalent in sediment porewater. Dynamic light scattering was used to monitor the hydrodynamic diameter of particles precipitating in laboratory solutions. Zn speciation was also measured by filtering the ZnS solutions (precipitation experiments and not to the dissolved organic ligands. X-ray photoelectron spectroscopy and electron microscopy were used to confirm that amorphous particles containing Zn and S were precipitating in the suspensions. Observed growth rates of ZnS particles varied by orders of magnitude, depending on the type and concentration of organic ligand in solution. In the presence of humic acid and thiol-containing ligands (cysteine, glutathione, and thioglycolate), observed growth rates decreased by 1-3 orders of magnitude relative to controls without the ligands. In contrast, growth rates of the particles were consistently within 1 order of magnitude of the ligand-free control when oxygen- and amine-containing ligands (oxalate, serine, and glycolate) were present Furthermore, particle growth rates decreased with an increase in thiol concentration and increased with NaNO3 electrolyte concentration. These studies suggest that specific surface interactions with thiol-containing organics may be one factor that contributes to the persistence of naturally occurring and anthropogenic

Study on the effect of free acidity and entrained TBP in UNPS on the quality of ADU powder

International Nuclear Information System (INIS)

Prudhvi Raju, P.V.S.N.; Mandal, D.

2015-01-01

Graphical abstract: From the experimental study it was found that mean particle size of precipitated Ammonium Di-Uranate (ADU) depends on the free acidity content and entrained TBP in Uranyl Nitrate Pure Solution (UNPS). It was found that as the free acidity as well as the entrained TBP content in UNPS increases, mean particle size of precipitated ADU decreases. Based on the experimental results two correlations were developed as shown in below figures. - Highlights: • The mean particle size of precipitated ADU depends on the free acidity in UNPS. • The mean particle size of precipitated ADU also depends on the entrained TBP in UNPS. • As free acidity in UNPS increases, mean particle size of precipitated ADU decreases. • As entrained TBP in UNPS increases, particle size of precipitated ADU decreases. • Based on the experimental results two correlations were developed to find d p of ADU. - Abstract: The mean particle size and size distribution of Ammonium Di-Uranate (ADU) particles, precipitated during the precipitation reaction of Uranyl Nitrate Pure Solution (UNPS) with ammonia play an important role on the sintered density of UO 2 pellets. The quality of precipitated ADU depends on number of process parameters viz., pH of UNPS, concentration of uranium in UNPS, flow rate of ammonium hydroxide, temperature etc. However, the effects of the presence of free acid and entrained Tri-Butyl-Phosphate (TBP) in UNPS on the quality of ADU powder were not studied till date. Experiments were conducted to study the effect of free acidity and the presence of entrained TBP on the quality of precipitated ADU particles. It was found that as the concentration of free acid as well as the concentration of entrained TBP in UNPS increases, the particle size of precipitated ADU decreases. Based on the experimental results two correlations were developed to determine the mean particle size of ADU; one is based on the free acid content of UNPS and the other is based on the

Study on the effect of free acidity and entrained TBP in UNPS on the quality of ADU powder

Energy Technology Data Exchange (ETDEWEB)

Prudhvi Raju, P.V.S.N. [Nuclear Fuel Complex, Hyderabad 500 062 (India); Mandal, D., E-mail: dmandal@barc.gov.in [Chemical Engineering Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

2015-09-15

Graphical abstract: From the experimental study it was found that mean particle size of precipitated Ammonium Di-Uranate (ADU) depends on the free acidity content and entrained TBP in Uranyl Nitrate Pure Solution (UNPS). It was found that as the free acidity as well as the entrained TBP content in UNPS increases, mean particle size of precipitated ADU decreases. Based on the experimental results two correlations were developed as shown in below figures. - Highlights: • The mean particle size of precipitated ADU depends on the free acidity in UNPS. • The mean particle size of precipitated ADU also depends on the entrained TBP in UNPS. • As free acidity in UNPS increases, mean particle size of precipitated ADU decreases. • As entrained TBP in UNPS increases, particle size of precipitated ADU decreases. • Based on the experimental results two correlations were developed to find d{sub p} of ADU. - Abstract: The mean particle size and size distribution of Ammonium Di-Uranate (ADU) particles, precipitated during the precipitation reaction of Uranyl Nitrate Pure Solution (UNPS) with ammonia play an important role on the sintered density of UO{sub 2} pellets. The quality of precipitated ADU depends on number of process parameters viz., pH of UNPS, concentration of uranium in UNPS, flow rate of ammonium hydroxide, temperature etc. However, the effects of the presence of free acid and entrained Tri-Butyl-Phosphate (TBP) in UNPS on the quality of ADU powder were not studied till date. Experiments were conducted to study the effect of free acidity and the presence of entrained TBP on the quality of precipitated ADU particles. It was found that as the concentration of free acid as well as the concentration of entrained TBP in UNPS increases, the particle size of precipitated ADU decreases. Based on the experimental results two correlations were developed to determine the mean particle size of ADU; one is based on the free acid content of UNPS and the other is based on

Urban acid deposition

Energy Technology Data Exchange (ETDEWEB)

Conlan, D.E.; Longhurst, J.W.S.; Gee, D.R.; Hare, S.E.

1991-07-01

In this document results from the Greater Manchester Acid Deposition Survey (GMADS), an urban precipitation chemistry network, for 1990 are presented. Full analytical methods are described along with the precision and accuracy of the methods used. The spatial variability of precipitation chemistry and deposition over this urban region was investigated using a network of twenty collectors. Concentrations of non marine sulphate, ammonium, calcium and hydrogen, and nitrogen dioxide gas concentrations all show significant spatial variability. The spatial variability of the deposition rates of non marine sulphate, nitrate, ammonium, hydrogen and calcium were significant. (Author).

Ionic flotation of uranium contained in industrial phosphoric acid

International Nuclear Information System (INIS)

Jdid; Blazy; Bessiere

1983-01-01

A new process for uranium recovery from industrial phosphoric acid at 30% of P 2 O 5 is applied by the ionic flotation process. Research is carried out on determination of the nature of ionic species of U in H 3 PO 4 5.5 M and the behavior of reagents from CECA Co. in very acid media. Reagents able to form complexes directly with uranium and stable in phosphoric acid selected are: potassium ethylene diamine tetra (methylene phosphonate) (INIPOL AD32) and sodium dialkyldiphosphonate (34S). Uranium IV, obtained by reduction of uranium VI with iron powder, is precipitated by these reagents. Flotation of the precipitate obtained with INIPOL AD 32 is realized by addition of hexylamino bis (methylene phosphonic acid). A recovery of 80 wt% is obtained. Flotation of the coprecipitate 34S-U(IV) is obtained without any other additions because 34S is a surfactant. Metal recovery is better than 90% and the coprecipitate contains more than 10% U. The process is fast precipitation 10 minutes and flotation 5 minutes and is efficient even at 60 0 C [fr

Changes of chemistry of precipitation on the area affected by imissions from hard coal power plant in the years 1977-1994

International Nuclear Information System (INIS)

Zablocki, Z.

1996-01-01

The changes of precipitation chemistry was studied on 9 sites in the distance 0.2-13.5 km from Dolna Odra power plant during the years 1977-1994. The results of long-term studies of changes of precipitation reaction and amounts of sulfur in precipitation on the area were shown as chronotoposequences. The results indicated on some positive changes in chemistry of precipitation in 1991-1994 years as compared to the period of 1986-1990 which manifested as decrease as yearly averages of amounts of sulfur and nitrate-nitrogen in precipitation and decrease of percentage of monthly measurements of precipitation with very acid reaction. (author). 11 refs, 2 figs, 1 tab

Optimisation of parameters for co-precipitation of uranium and plutonium - results of simulation studies

International Nuclear Information System (INIS)

Pandey, N.K.; Velvandan, P.V.; Murugesan, S.; Ahmed, M.K.; Koganti, S.B.

1999-01-01

Preparation of plutonium oxide from plutonium nitrate solution generally proceeds via oxalate precipitation route. In a nuclear fuel reprocessing scheme this step succeeds the partitioning step (separation of uranium and plutonium). Results of present studies confirm that it is possible to avoid partitioning step and recover plutonium and uranium as co-precipitated product. This also helps in minimising the risk of proliferation of fissile material. In this procedure, the solubility of uranium oxalate in nitric acid is effectively used. Co-precipitation parameters are optimised with simulated solutions of uranium nitrate and thorium nitrate (in place of plutonium). On the basis of obtained results a reconversion flow-sheet is designed and reported here. (author)

Climate change and precipitation: Detecting changes Climate change and precipitation: Detecting changes

International Nuclear Information System (INIS)

Van Boxel, John H

2001-01-01

Precipitation is one of the most, if not the most important climate parameter In most studies on climate change the emphasis is on temperature and sea level rise. Often too little attention is given to precipitation. For a large part this is due to the large spatial en temporal variability of precipitation, which makes the detection of changes difficult. This paper describes methods to detect changes in precipitation. In order to arrive at statistically significant changes one must use long time series and spatial averages containing the information from several stations. In the Netherlands the average yearly precipitation increased by 11% during the 20th century .In the temperate latitudes on the Northern Hemisphere (40-60QN) the average increase was about 7% over the 20th century and the globally averaged precipitation increased by about 3%. During the 20th century 38% of the land surface of the earth became wetter, 42% experienced little change (less than 5% change) and 20% became dryer. More important than the average precipitation is the occurrence of extremes. In the Netherlands there is a tendency to more extreme precipitations, whereas the occurrence of relatively dry months has not changed. Also in many other countries increases in heavy precipitation events are observed. All climate models predict a further increase of mean global precipitation if the carbon dioxide concentration doubles. Nevertheless some areas get dryer, others have little change and consequently there are also areas where the increase is much more than the global average. On a regional scale however there are large differences between the models. Climate models do not yet provide adequate information on changes in extreme precipitations

Precipitous Birth

Directory of Open Access Journals (Sweden)

Jennifer Yee

2017-09-01

Full Text Available Audience: This scenario was developed to educate emergency medicine residents on the management of a precipitous birth in the emergency department (ED. The case is also appropriate for teaching of medical students and advanced practice providers, as well as reviewing the principles of crisis resource management, teamwork, and communication. Introduction: Patients with precipitous birth require providers to manage two patients simultaneously with limited time and resources. Crisis resource management skills will be tested once baby is delivered, and the neonate will require assessment for potential neonatal resuscitation. Objectives: At the conclusion of the simulation session, learners will be able to manage women who have precipitous deliveries, as well as perform neonatal assessment and management. Method: This session was conducted using high-fidelity simulation, followed by a debriefing session and lecture on precipitous birth management and neonatal evaluation.

Magnesium hydroxide as the neutralizing agent for radioactive hydrochloric acid solutions

International Nuclear Information System (INIS)

Palmer, M.J.; Fife, K.W.

1995-10-01

The current technology at Los Alamos for removing actinides from acidic chloride waste streams is precipitation with approximately 10 M potassium hydroxide. Although successful, there are many inherent drawbacks to this precipitation technique which will be detailed in this paper. Magnesium hydroxide (K sp = 1.3 x 10 -11 ) has limited solubility in water and as a result of the common ion effect, cannot generate a filtrate with a pH greater than 9. At a pH of 9, calcium (K sp = 5.5 x 10 -6 ) will not coprecipitate as the hydroxide. This is an important factor since many acidic chloride feeds to hydroxide precipitation contain significant amounts of calcium. In addition, neutralization with Mg(OH) 2 produces a more filterable precipitate because neutralization occurs as the Mg(OH) 2 is dissolved by the acid rather than as a result of the much faster liquid/liquid reaction of KOH with the waste acid. This slower solid/liquid reaction allows time for crystal growth to occur and produces more easily filterable precipitates. On the other hand, neutralization of spent acid with strong KOH that yields numerous hydroxide ions in solution almost instantaneously forming a much larger volume of small crystallites that result in gelatinous, slow-filtering precipitates. Magnesium hydroxide also offers a safety advantage. Although mildly irritating, it is a weak base and safe and easy to handle. From a waste minimization perspective, Mg(OH) 2 offers many advantages. First, the magnesium hydroxide is added as a solid. This step eliminates the diluent water used in KOH neutralizations. Secondly, because the particle size of the precipitate is larger, more actinides are caught on the filter paper resulting in a smaller amount of actinide being transferred to the TA-50 Liquid Waste Treatment Facility. Third, the amount of solids that must be reprocessed is significantly smaller resulting in less waste generation from the downstream processes

Precipitation isoscapes for New Zealand: enhanced temporal detail using precipitation-weighted daily climatology.

Science.gov (United States)

Baisden, W Troy; Keller, Elizabeth D; Van Hale, Robert; Frew, Russell D; Wassenaar, Leonard I

2016-01-01

Predictive understanding of precipitation δ(2)H and δ(18)O in New Zealand faces unique challenges, including high spatial variability in precipitation amounts, alternation between subtropical and sub-Antarctic precipitation sources, and a compressed latitudinal range of 34 to 47 °S. To map the precipitation isotope ratios across New Zealand, three years of integrated monthly precipitation samples were acquired from >50 stations. Conventional mean-annual precipitation δ(2)H and δ(18)O maps were produced by regressions using geographic and annual climate variables. Incomplete data and short-term variation in climate and precipitation sources limited the utility of this approach. We overcome these difficulties by calculating precipitation-weighted monthly climate parameters using national 5-km-gridded daily climate data. This data plus geographic variables were regressed to predict δ(2)H, δ(18)O, and d-excess at all sites. The procedure yields statistically-valid predictions of the isotope composition of precipitation (long-term average root mean square error (RMSE) for δ(18)O = 0.6 ‰; δ(2)H = 5.5 ‰); and monthly RMSE δ(18)O = 1.9 ‰, δ(2)H = 16 ‰. This approach has substantial benefits for studies that require the isotope composition of precipitation during specific time intervals, and may be further improved by comparison to daily and event-based precipitation samples as well as the use of back-trajectory calculations.

Cerium oxalate precipitation

International Nuclear Information System (INIS)

Chang, T.P.

1987-02-01

Cerium, a nonradioactive, common stand-in for plutonium in development work, has been used to simulate several plutonium precipitation processes at the Savannah River Laboratory. There are similarities between the plutonium trifluoride and the cerium oxalate precipitations in particle size and extent of plating, but not particle morphology. The equilibrium solubility, precipitation kinetics, particle size, extent of plating, and dissolution characteristics of cerium oxalate have been investigated. Interpretations of particle size and plating based on precipitation kinetics (i.e., nucleation and crystal growth) are presented. 16 refs., 7 figs., 6 tabs

Cintichem modified process - {sup 99}Mo precipitation step: application of statistical analysis tools over the reaction parameters

Energy Technology Data Exchange (ETDEWEB)

Teodoro, Rodrigo; Dias, Carla R.B.R.; Osso Junior, Joao A., E-mail: jaosso@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Fernandez Nunez, Eutimio Gustavo [Universidade de Sao Paulo (EP/USP), SP (Brazil). Escola Politecnica. Dept. de Engenharia Quimica

2011-07-01

Precipitation of {sup 99}Mo by {alpha}-benzoin oxime ({alpha}-Bz) is a standard precipitation method for molybdenum due the high selectivity of this agent. Nowadays, statistical analysis tools have been employed in analytical systems to prove its efficiency and feasibility. IPEN has a project aiming the production of {sup 99}Mo by the fission of {sup 235}U route. The processing uses as the first step the precipitation of {sup 99}Mo with {alpha}-Bz. This precipitation step involves many key reaction parameters. The aim of this work is based on the development of the already known acidic route to produce {sup 99}Mo as well as the optimization of the reactional parameters applying statistical tools. In order to simulate {sup 99}Mo precipitation, the study was conducted in acidic media using HNO{sub 3}, {alpha}Bz as precipitant agent and NaOH /1%H{sub 2}O{sub 2} as dissolver solution. Then, a Mo carrier, KMnO{sub 4} solutions and {sup 99}Mo tracer were added to the reaction flask. The reactional parameters ({alpha}-Bz/Mo ratio, Mo carrier, reaction time and temperature, and cooling reaction time before filtration) were evaluated under a fractional factorial design of resolution V. The best values of each reactional parameter were determined by a response surface statistical planning. The precipitation and recovery yields of {sup 99}Mo were measured using HPGe detector. Statistical analysis from experimental data suggested that the reactional parameters {alpha}-Bz/Mo ratio, reaction time and temperature have a significant impact on {sup 99}Mo precipitation. Optimization statistical planning showed that higher {alpha}Bz/Mo ratios, room temperature, and lower reaction time lead to higher {sup 99}Mo yields. (author)

Amino acid salt solutions as solvents in CO2 capture from flue gas

DEFF Research Database (Denmark)

Lerche, Benedicte Mai; Thomsen, Kaj; Stenby, Erling Halfdan

New solvents based on the salts of amino acids have emerged as an alternative to the alkanolamine solutions, for the chemical absorption of CO2 from flue gas. But only few studies on amino acids as CO2 capturing agents have been performed so far. One of the interesting features of amino acid salt...... solutions is their ability to form solid precipitates upon the absorption of CO2. The occurrence of crystallization offers the possibility of increasing the CO2 loading capacity of the solvent. However, precipitation can also have negative effect on the CO2 capture process. The chemical nature of the solid...... of glycine, taurine, and lysine, while in the case of proline, and glutamic acid, the precipitate was found to be bicarbonate. These results give an important contribution to further understanding the potential of amino acid salt solutions in CO2 capture from flue gas....

Urban acid deposition in Greater Manchester

Energy Technology Data Exchange (ETDEWEB)

Lee, D.S.; Longhurst, J.W.S.; Gee, D.R.; Hare, S.E. (Manchester Polytechnic, Manchester (UK). Acid Rain Information Centre)

1989-08-01

Data are presented from a monitoring network of 18 bulk precipitation collectors and one wet-only collector in the urban area of Greater Manchester, in the north west of England. Weekly samples were analysed for all the major ions in precipitation along with gaseous nitrogen dioxide concentrations from diffusion tubes. Statistical analysis of the data shows significant spatial variation of non marine sulphate, nitrate, ammonium, acidity and calcium concentrations, and nitrogen dioxide concentrations. Calcium is thought to be responsible for the buffering of acidity and is of local origin. Wet deposition is the likely removal process for calcium in the atmosphere and probably by below cloud scavenging. Nitrate and ammonium concentrations and depositions show close spatial, temporal and statistical association. Examination of high simultaneous episodes of nitrate and ammonium deposition shows that these depositions cannot be explained in terms of trajectories and it is suggested that UK emissions of ammonia may be important. Statistical analysis of the relationships between nitrate and ammonium depositions, concentrations and precipitation amount suggest that ammonia from mesoscale sources reacts reversibly with nitric acid aerosol and is removed by below cloud scavenging. High episodes of the deposition of non marine sulphate are difficult to explain by trajectory analysis alone, perhaps suggesting local sources. In a comparison between wet deposition and bulk deposition, it was shown that only 15.2% of the non marine sulphur was dry deposited to the bulk precipitation collector. 63 refs., 86 figs., 31 tabs.

Nucleic acid-binding glycoproteins which solubilize nucleic acids in dilute acid: re-examination of the Ustilago maydis glycoproteins

Energy Technology Data Exchange (ETDEWEB)

Unrau, P.; Champ, D.R.; Young, J.L.; Grant, C.E.

1980-01-01

Holloman reported the isolation from Ustilago maydis of a glycoprotein which prevented the precipitation of nucleic acids in cold 5% trichloroacetic acid. Two glycoprotein fractions from U. maydis with this nucleic acid-solubilizing activity were isolated in our laboratory using improved purification procedures. The activity was not due to nuclease contamination. The glycoproteins are distinguished by: their ability to bind to concanavalin A-Sepharose; their differential binding to double- and single-stranded deoxyribonucleic acid, and to ribonucleic acid; their molecular weights (46,000 and 69,000); and the relative amounts present in growing versus nongrowing cells. Both fractions required sulfhydryl-reducing conditions for optimal yields, specific activity, and stability. Nucleic acid binding was cooperative, the minimum number of glycoproteins required to make a native T7 DNA molecule soluble in dilute acid being estimated at 2 and 15, respectively.

Citric acid fermentation medium from sugar waste

Energy Technology Data Exchange (ETDEWEB)

Asai, S.; Yarita, K.; Uchio, R.; Kikuchi, K.

1977-11-02

Wastes from a sugar refinery are hydrolyzed to yield fructose and glucose; a part of the fructose is removed from the hydrolyzate by treating with lime and the remaining hydrolyzate is used as a C source for citric acid fermentation. Thus, 1 kg beet molasses was dissolved in 2.5 L water, adjusted to pH 1.5, hydrolyzed at 60/sup 0/ for 4 h, neutralized with Ca(OH)/sub 2/, and the precipitate was removed. The hydrolyzate was cooled to 0/sup 0/, mixed with a solution containing 205 g Ca(OH)/sub 2/, seeded with fructose, and allowed to stand. The precipitate was suspended in cold water, neutralized with H/sub 2/SO/sub 4/, and filtered to obtain a solution containing 169 g fructose and 6.3 g glucose. The filtrate from the Ca(OH)/sub 2/ precipitation was neutralized with H/sub 2/SO/sub 4/ and removal of precipitate yielded a solution containing 87 g fructose and 220 g glucose, which was used as a C source for citric acid fermentation with Aspergillus niger AJ7015.

Precipitation of flaky moolooite and its thermal decomposition

Science.gov (United States)

Wu, Jin-yu; Huang, Kai

2016-08-01

Moolooite particles with flaky morphology were synthesized by mixing dilute solutions of copper nitrate and sodium oxalate in the presence of citric acid. Solution pH value, citric acid concentration, and stirring were found to have large effect on the shape of the precipitated particles. Under the stirring, the radial area of flaky moolooite particles was enlarged and extended to become a thinner and larger flake. This is ascribed to growth promotion caused by the selective absorption of citric ligands onto a particular crystalline surface of the moolooite particles. Flaky shape of the moolooite particles tended to become spherical and disappeared completely when decomposed under an Ar atmosphere, leading to the formation of large porous aggregated particles composed of many tiny nanosized copper crystals.

Photodegradation of Acid Black 1 and Removing Heavy Metals from the Water by an Inorganic Nanocomposite Synthesized via Simple Co-Precipitation Method

Directory of Open Access Journals (Sweden)

Marziyeh Mohammadi

2016-07-01

Full Text Available In this experimental work, PbS/ZnS/ZnO nanocomposite was synthesized via a simple co-precipitation method. The effect of Zn2+/Pb2+ mole ratio was investigated on the product size and morphology. The products were characterized via scanning electron microscopy to obtain product size and morphology. The optical properties of the nanocomposites were studied by ultra violet-visible spectroscopy. Photocatalytic activity of the product was examine by decomposition of acid black 1 as dye. To investigation of the effect of as synthesized nanocomposite on the water treatment, the influences of the nanocomposite to remove heavy ions was studied by atomic absorption spectroscopy. The results showed that the synthesized nanocomposite has well optical properties, photocatalytic and water treatment activities.

National Acid Precipitation Assessment Program: 1990 Integrated Assessment report

International Nuclear Information System (INIS)

1991-11-01

The document, the 'Integrated Assessment,' is a summary of the causes and effects of acidic deposition and a comparison of the costs and effectiveness of alternative emission control scenarios. In developing the 'Integrated Assessment,' it was NAPAP's goal to produce a structured compilation of policy-relevant technical information. The Integrated Assessment is based on findings and data from a series of twenty-seven State-of-Science/Technology Reports (SOS/T) on acidic deposition published by NAPAP in 1990. The scope of the documents includes: (1) emissions, atmospheric processes and deposition; (2) effects on surface waters, forests, agricultural crops, exposed materials, human health, and visibility; and (3) control technologies, future emissions, and effects valuation

Effects of different oxyanions in solution on the precipitation of jarosite at room temperature.

Science.gov (United States)

Yeongkyoo, Kim

2018-04-09

The effects of five different oxyanions, AsO 4 , SeO 3 , SeO 4 , MoO 4 , and CrO 4 , on the precipitation of jarosite at room temperature were investigated by X-ray diffraction, scanning electron microscopy, and chemical analysis. Different amounts (2, 5, and 10 mol%) of oxyanions in the starting solution and different aging times (1 h-40 days) were used for the experiment. In the initial stage, only the amorphous phase appears for all samples. With increasing aging time, jarosite and jarosite with oxyanions start precipitating at room temperature with different precipitation rates and crystallinities. Jarosite with AsO 4 shows the lowest precipitation rate and lowest crystallinity. With increasing amounts of oxyanions, the crystallization rate decreases, especially for jarosite with AsO 4 . The jarosite samples with CrO 4 and SeO 4 show the fastest precipitation and highest crystallinities. For the jarosite samples with a low precipitation rate and low crystallinity, the amorphous phase contains high concentrations of oxyanions, probably because of the fast precipitation of the amorphous iron oxyanion phase; however, the phase with fast jarosite precipitation contains fewer oxyanions. The results show that coprecipitation of jarosite can play a more important role in controlling the behavior of CrO 4 than AsO 4 in acid mine drainage. Copyright © 2018 Elsevier B.V. All rights reserved.

The role of amino acids in hydroxyapatite mineralization

Science.gov (United States)

2016-01-01

Polar and charged amino acids (AAs) are heavily expressed in non-collagenous proteins (NCPs), and are involved in hydroxyapatite (HA) mineralization in bone. Here, we review what is known on the effect of single AAs on HA precipitation. Negatively charged AAs, such as aspartic acid, glutamic acid (Glu) and phosphoserine are largely expressed in NCPs and play a critical role in controlling HA nucleation and growth. Positively charged ones such as arginine (Arg) or lysine (Lys) are heavily involved in HA nucleation within extracellular matrix proteins such as collagen. Glu, Arg and Lys intake can also increase bone mineral density by stimulating growth hormone production. In vitro studies suggest that the role of AAs in controlling HA precipitation is affected by their mobility. While dissolved AAs are able to inhibit HA precipitation and growth by chelating Ca2+ and PO43− ions or binding to nuclei of calcium phosphate and preventing their further growth, AAs bound to surfaces can promote HA precipitation by attracting Ca2+ and PO43− ions and increasing the local supersaturation. Overall, the effect of AAs on HA precipitation is worth being investigated more, especially under conditions closer to the physiological ones, where the presence of other factors such as collagen, mineralization inhibitors, and cells heavily influences HA precipitation. A deeper understanding of the role of AAs in HA mineralization will increase our fundamental knowledge related to bone formation, and could lead to new therapies to improve bone regeneration in damaged tissues or cure pathological diseases caused by excessive mineralization in tissues such as cartilage, blood vessels and cardiac valves. PMID:27707904

Organic acids as analytical reagent: Part 1. Estimation of zirconium by gallic acid

Energy Technology Data Exchange (ETDEWEB)

Pande, C S; Singh, A K; Kumar, Ashok [Lucknow Univ. (India). Dept. of Chemistry

1975-07-01

Gallic acid has been found to be a selective reagent for the estimation of zirconium. The acid gives a crystalline precipitate at pH of 4.8 which is ignited and weighed as ZrO/sub 2/. Cations like Ca/sup +2/, Ba/sup +2/, Sr/sup +2/, Mn/sup +2/, Co/sup +2/, Ni/sup +2/, Fe/sup +3/ do not interfere in the estimation.

Aerosol and precipitation chemistry in the southwestern United States: spatiotemporal trends and interrelationships

Science.gov (United States)

Sorooshian, A.; Shingler, T.; Harpold, A.; Feagles, C. W.; Meixner, T.; Brooks, P. D.

2013-01-01

This study characterizes the spatial and temporal patterns of aerosol and precipitation composition at six sites across the United States Southwest between 1995 and 2010. Precipitation accumulation occurs mostly during the wintertime (December–February) and during the monsoon season (July–September). Rain and snow pH levels are usually between 5–6, with crustal-derived species playing a major role in acid neutralization. These species (Ca2+, Mg2+, K+, Na+) exhibit their highest concentrations between March and June in both PM2.5 and precipitation due mostly to dust. Crustal-derived species concentrations in precipitation exhibit positive relationships with SO42−, NO3−, and Cl–, suggesting that acidic gases likely react with and partition to either crustal particles or hydrometeors enriched with crustal constituents. Concentrations of particulate SO42− show a statistically significant correlation with rain SO42− unlike snow SO42−, which may be related to some combination of the vertical distribution of SO42− (and precursors) and the varying degree to which SO42−-enriched particles act as cloud condensation nuclei versus ice nuclei in the region. The coarse : fine aerosol mass ratio was correlated with crustal species concentrations in snow unlike rain, suggestive of a preferential role of coarse particles (mainly dust) as ice nuclei in the region. Precipitation NO3− : SO42− ratios exhibit the following features with potential explanations discussed: (i) they are higher in precipitation as compared to PM2.5; (ii) they exhibit the opposite annual cycle compared to particulate NO3− : SO42− ratios; and (iii) they are higher in snow relative to rain during the wintertime. Long-term trend analysis for the monsoon season shows that the NO3− : SO42− ratio in rain increased at the majority of sites due mostly to air pollution regulations of SO42− precursors. PMID:24432030

Aerosol and precipitation chemistry in the southwestern United States: spatiotemporal trends and interrelationships

Directory of Open Access Journals (Sweden)

A. Sorooshian

2013-08-01

Full Text Available This study characterizes the spatial and temporal patterns of aerosol and precipitation composition at six sites across the United States Southwest between 1995 and 2010. Precipitation accumulation occurs mostly during the wintertime (December–February and during the monsoon season (July–September. Rain and snow pH levels are usually between 5–6, with crustal-derived species playing a major role in acid neutralization. These species (Ca2+, Mg2+, K+, Na+ exhibit their highest concentrations between March and June in both PM2.5 and precipitation due mostly to dust. Crustal-derived species concentrations in precipitation exhibit positive relationships with SO42−, NO3−, and Cl−, suggesting that acidic gases likely react with and partition to either crustal particles or hydrometeors enriched with crustal constituents. Concentrations of particulate SO42− show a statistically significant correlation with rain SO42− unlike snow SO42−, which may be related to some combination of the vertical distribution of SO42− (and precursors and the varying degree to which SO42−-enriched particles act as cloud condensation nuclei versus ice nuclei in the region. The coarse : fine aerosol mass ratio was correlated with crustal species concentrations in snow unlike rain, suggestive of a preferential role of coarse particles (mainly dust as ice nuclei in the region. Precipitation NO3− : SO42− ratios exhibit the following features with potential explanations discussed: (i they are higher in precipitation as compared to PM2.5; (ii they exhibit the opposite annual cycle compared to particulate NO3− : SO42− ratios; and (iii they are higher in snow relative to rain during the wintertime. Long-term trend analysis for the monsoon season shows that the NO3− : SO42− ratio in rain increased at the majority of sites due mostly to air pollution regulations of SO42− precursors.

Raise of efficiency of flocculation-precipitation treatment of exuding water from reclaimed land by irradiation

International Nuclear Information System (INIS)

Sawai, Teruko; Yamazaki, Masao; Sawai, Takeshi

1984-01-01

When rain falls on the coastal reclaimed land filled with home garbage in Tokyo, a large quantity of water containing much organic contaminant flows out. It is difficult to treat this water exuding from reclaimed land by conventional method. Because the water with low BOD which is difficult to treat by biological process flows out for long period after the stabilization of reclaimed land. When the water is treated by flocculation and precipitation, the substances with high molecular weight are easily removed, but the rate of removal of fulvic acid with low molecular weight, which accounts for more than 60% of the composition of the water, is very poor. Therefore, it was examined to change the fulvic acid to high molecular weight by irradiation, and to improve the efficiency of the flocculation-precipitation treatment of exuding water. Exuding water was sampled in Tokyo Bay No.15 reclaimed land, and it was separated into humic acid and fulvic acid. The Co-60 gamma ray of 5 kCi was irradiated to the samples. The experimental method and the results are reported. The change of fulvic acid to high molecular weight by irradiation was most efficient at pH 2.2. More than 90% of organic contaminants was able to be removed. (Kako, I.)

Comparative analysis of amino acids and amino-acid derivatives in protein crystallization

International Nuclear Information System (INIS)

Ito, Len; Shiraki, Kentaro; Yamaguchi, Hiroshi

2010-01-01

New types of aggregation suppressors, such as amino acids and their derivatives, were focused on as fourth-component additives. Data were obtained that indicated that the additives promote protein crystallization. Optimal conditions for protein crystallization are difficult to determine because proteins tend to aggregate in saturated solutions. This study comprehensively evaluates amino acids and amino-acid derivatives as additives for crystallization. This fourth component of the solution increases the probability of crystallization of hen egg-white lysozyme in various precipitants owing to a decrease in aggregation. These results suggest that the addition of certain types of amino acids and amino-acid derivatives, such as Arg, Lys and esterified and amidated amino acids, is a simple method of improving the success rate of protein crystallization

Ammonia-Oxidizing Archaea Are More Resistant Than Denitrifiers to Seasonal Precipitation Changes in an Acidic Subtropical Forest Soil

Directory of Open Access Journals (Sweden)

Jie Chen

2017-07-01

Full Text Available Seasonal precipitation changes are increasingly severe in subtropical areas. However, the responses of soil nitrogen (N cycle and its associated functional microorganisms to such precipitation changes remain unclear. In this study, two projected precipitation patterns were manipulated: intensifying the dry-season drought (DD and extending the dry-season duration (ED but increasing the wet-season storms following the DD and ED treatment period. The effects of these two contrasting precipitation patterns on soil net N transformation rates and functional gene abundances were quantitatively assessed through a resistance index. Results showed that the resistance index of functional microbial abundance (-0.03 ± 0.08 was much lower than that of the net N transformation rate (0.55 ± 0.02 throughout the experiment, indicating that microbial abundance was more responsive to precipitation changes compared with the N transformation rate. Spring drought under the ED treatment significantly increased the abundances of both nitrifying (amoA and denitrifying genes (nirK, nirS, and nosZ, while changes in these gene abundances overlapped largely with control treatment during droughts in the dry season. Interestingly, the resistance index of the ammonia-oxidizing archaea (AOA amoA abundance was significantly higher than that of the denitrifying gene abundances, suggesting that AOA were more resistant to the precipitation changes. This was attributed to the stronger environmental adaptability and higher resource utilization efficiency of the AOA community, as indicated by the lack of correlations between AOA gene abundance and environmental factors [i.e., soil water content, ammonium (NH4+ and dissolved organic carbon concentrations] during the experiment.

Effective removal of coordinated copper from wastewater using a new dithiocarbamate-type supramolecular heavy metal precipitant.

Science.gov (United States)

Fu, Fenglian; Zeng, Haiyan; Cai, Qinhong; Qiu, Rongliang; Yu, Jimmy; Xiong, Ya

2007-11-01

A new dithiocarbamate-type heavy metal precipitant, sodium 1,3,5-hexahydrotriazinedithiocarbamate (HTDC), was prepared and used to remove coordinated copper from wastewater. In the reported dithiocarbamate-type precipitants, HTDC possesses the highest percentage of the effective functional groups. It could effectively precipitate copper to less than 0.5mgl(-1) from both synthetic and actual industrial wastewater containing CuEDTA in the range of pH 3-9. UV-vis spectral investigation and elemental analysis suggested that the precipitate was a kind of coordination supramolecular compound, [Cu(3)(HTDC)(2)](n). The toxicity characteristic leaching procedure (TCLP) and semi-dynamic leaching test (SDLT) indicated that the supramolecular precipitate was non-hazardous and stable in weak acid and alkaline conditions. Tests of an anion exchange resin D231 provided a clue to simultaneously remove excess HTDC and residual CuEDTA in practical process of wastewater treatment.

Precipitation behavior and effect of new precipitated β phase in AZ80 magnesium alloy

Institute of Scientific and Technical Information of China (English)

TANG Wei; HAN En-hou; XU Yong-bo; LIU Lu

2006-01-01

Granular precipitate that was a new kind of β-Mg17Al12 phase found in aged AZ80 wrought Mg alloy at all aging temperature was studied. The structure and precipitation behavior of this granular β-Mg17Al12 precipitate were studied by environmental scanning electron microscopy (ESEM) and transmission electron microscopy (TEM). The effect of the granular precipitate on mechanical properties of AZ80 alloy was also studied. The new precipitate that was granular and nucleated both on grain boundaries (GBs) and twin boundaries, has the same crystal structure and lattice parameter as those of the continuous or discontinuous precipitated β-Mg17Al12. And the nucleation and growth of the granular precipitate are faster than those of the other two precipitates at higher temperatures (above 583 K), but are suppressed at lower temperatures (below 423 K). At lower temperatures, the discontinuous β-Mg17Al12 precipitates firstly and the granular β-Mg17Al12 precipitates after aged more than 40 h. The crack is easily nucleated on the phase boundaries of granular phase and matrix because of the weak binding force. As a result, the strength and ductility of AZ80 Mg alloy are decreased by the granular β-Mg17Al12 precipitate.

A review of acidity generation and consumption in acidic coal mine lakes and their watersheds.

Science.gov (United States)

Blodau, Christian

2006-10-01

Lakes developing in former coal mine pits are often characterized by high concentrations of sulfate and iron and low pH. The review focuses on the causes for and fate of acidity in these lakes and their watersheds. Acidification is primarily caused by the generation of ferrous iron bearing and mineralized groundwater, transport through the groundwater-surface water interface, and subsequent iron oxidation and precipitation. Rates of acidity generation in mine tailings and dumps, and surface water are often similar (1 to >10 mol m(-2) yr(-1)). Weathering processes, however, often suffice to buffer groundwaters to only moderately acidic or neutral pH, depending on the suite of minerals present. In mine lakes, the acidity balance is further influenced by proton release from transformation of metastable iron hydroxysulfate minerals to goethite, and proton and ferrous iron sequestration by burial of iron sulfides and carbonates in sediments. These processes mostly cannot compensate acidity loading from the watershed, though. A master variable for almost all processes is the pH: rates of pyrite oxidation, ferrous iron oxidation, mineral dissolution, iron precipitation, iron hydroxide transformation, and iron and sulfate reduction are strongly pH dependent. While the principle mechanism of acidity generation and consumption and several controls are mostly understood, this cannot be said about the fate of acidity on larger spatial and temporal scales. Little is also known about critical loads and the internal regulation of biogeochemical iron, sulfur, and carbon cycling in acidic mine lakes.

A review of acidity generation and consumption in acidic coal mine lakes and their watersheds

International Nuclear Information System (INIS)

Blodau, Christian

2006-01-01

Lakes developing in former coal mine pits are often characterized by high concentrations of sulfate and iron and low pH. The review focuses on the causes for and fate of acidity in these lakes and their watersheds. Acidification is primarily caused by the generation of ferrous iron bearing and mineralized groundwater, transport through the groundwater-surface water interface, and subsequent iron oxidation and precipitation. Rates of acidity generation in mine tailings and dumps, and surface water are often similar (1 to >10 mol m -2 yr -1 ). Weathering processes, however, often suffice to buffer groundwaters to only moderately acidic or neutral pH, depending on the suite of minerals present. In mine lakes, the acidity balance is further influenced by proton release from transformation of metastable iron hydroxysulfate minerals to goethite, and proton and ferrous iron sequestration by burial of iron sulfides and carbonates in sediments. These processes mostly cannot compensate acidity loading from the watershed, though. A master variable for almost all processes is the pH: rates of pyrite oxidation, ferrous iron oxidation, mineral dissolution, iron precipitation, iron hydroxide transformation, and iron and sulfate reduction are strongly pH dependent. While the principle mechanism of acidity generation and consumption and several controls are mostly understood, this cannot be said about the fate of acidity on larger spatial and temporal scales. Little is also known about critical loads and the internal regulation of biogeochemical iron, sulfur, and carbon cycling in acidic mine lakes. (author)

Dissolution of copper and iron from malachite ore and precipitation of copper sulfate pentahydrate by chemical process

Directory of Open Access Journals (Sweden)

H. Kokes

2014-03-01

Full Text Available The present work describes an investigation of a chemical process for the recovery of copper and iron from malachite ore. For the dissolution of copper and iron, H2SO4 was employed as well as H2O2 as an oxidizing agent. The effects of reaction temperature and time, acid concentration, liquid-to-solid ratio and agitation rate on the copper and iron percentage were investigated. Following the steps of dissolving the copper and iron sulfate and filtering, iron (III hydroxide was precipitated by adjusting the pH level of the solution. Subsequently, copper sulfate pentahydrate was obtained by using various precipitants (i.e. ethanol, methanol and sulfuric acid.

Comparison of Precipitated Calcium Carbonate/Polylactic Acid and Halloysite/Polylactic Acid Nanocomposites

Directory of Open Access Journals (Sweden)

Xuetao Shi

2015-01-01

Full Text Available PLA nanocomposites with stearate coated precipitated calcium carbonate (PCC and halloysite natural nanotubes (HNT were prepared by melt extrusion. The crystallization behavior, mechanical properties, thermal dynamical mechanical analysis (DMTA, and the morphology of the PCC/PLA, HNT/PLA, and HNT/PCC/PLA composites were discussed. Compared to halloysite nanotubes, PCC nanoparticles showed a better nucleating effect, which decreased both the glass transition and cold crystallization temperatures. The tensile performance of PLA composites showed that the addition of inorganic nanofillers increased Young’s modulus but decreased tensile strength. More interestingly, PLA composites with PCC particles exhibited an effectively increased elongation at break with respect to pure PLA, while HNT/PLA showed a decreased ultimate deformation of composites. DMTA results indicated that PLA composites had a similar storage modulus at temperatures below the glass transition and the addition of nanofillers into PLA caused Tg to shift to lower temperatures by about 3°C. The morphological analysis of fractures surface of PLA nanocomposites showed good dispersion of nanofillers, formation of microvoids, and larger plastic deformation of the PLA matrix when the PCC particles were added, while a strong aggregation was noticed in composites with HNT nanofillers, which has been attributed to a nonoptimal surface coating.

Asymmetric responses of primary productivity to precipitation extremes: A synthesis of grassland precipitation manipulation experiments.

Science.gov (United States)

Wilcox, Kevin R; Shi, Zheng; Gherardi, Laureano A; Lemoine, Nathan P; Koerner, Sally E; Hoover, David L; Bork, Edward; Byrne, Kerry M; Cahill, James; Collins, Scott L; Evans, Sarah; Gilgen, Anna K; Holub, Petr; Jiang, Lifen; Knapp, Alan K; LeCain, Daniel; Liang, Junyi; Garcia-Palacios, Pablo; Peñuelas, Josep; Pockman, William T; Smith, Melinda D; Sun, Shanghua; White, Shannon R; Yahdjian, Laura; Zhu, Kai; Luo, Yiqi

2017-10-01

Climatic changes are altering Earth's hydrological cycle, resulting in altered precipitation amounts, increased interannual variability of precipitation, and more frequent extreme precipitation events. These trends will likely continue into the future, having substantial impacts on net primary productivity (NPP) and associated ecosystem services such as food production and carbon sequestration. Frequently, experimental manipulations of precipitation have linked altered precipitation regimes to changes in NPP. Yet, findings have been diverse and substantial uncertainty still surrounds generalities describing patterns of ecosystem sensitivity to altered precipitation. Additionally, we do not know whether previously observed correlations between NPP and precipitation remain accurate when precipitation changes become extreme. We synthesized results from 83 case studies of experimental precipitation manipulations in grasslands worldwide. We used meta-analytical techniques to search for generalities and asymmetries of aboveground NPP (ANPP) and belowground NPP (BNPP) responses to both the direction and magnitude of precipitation change. Sensitivity (i.e., productivity response standardized by the amount of precipitation change) of BNPP was similar under precipitation additions and reductions, but ANPP was more sensitive to precipitation additions than reductions; this was especially evident in drier ecosystems. Additionally, overall relationships between the magnitude of productivity responses and the magnitude of precipitation change were saturating in form. The saturating form of this relationship was likely driven by ANPP responses to very extreme precipitation increases, although there were limited studies imposing extreme precipitation change, and there was considerable variation among experiments. This highlights the importance of incorporating gradients of manipulations, ranging from extreme drought to extreme precipitation increases into future climate change

Separation of Am-Cm from NaNO3 waste solutions by in-canyon-tank precipitation as oxalates

International Nuclear Information System (INIS)

Gray, L.W.; Burney, G.A.; Wilson, T.W.; McKibben, J.M.

1981-09-01

A process for the purification of Am-Cm residues was developed specifically for application in Savannah River Plant (SRP) canyon tanks. These Am-Cm residues were collected from several campaigns to produce plutonium containing high isotopic concentrations of 240 Pu. An initial purification from Al 3+ had already been accomplished by a solvent extraction process. The product of this process was contaminated with NaNO 3 as a result of entrainment of the solvent extraction NaNO 3 scrub solution. To produce an acceptable feed solution for a later pressurized cation exchange chromatography separation and purification step, the bulk of the NaNO 3 must be removed. This purification process includes formic acid denitration, adjustment of contaminating cations by evaporation and water dilution, and oxalate precipitation of the actinides and lanthanides. After washing, the precipitate was dissolved in 8M nitric acid, and the oxalate was destroyed by nitric acid oxidation

Precipitate hydrolysis process for the removal of organic compounds from nuclear waste slurries

Science.gov (United States)

Doherty, J.P.; Marek, J.C.

1987-02-25

A process for removing organic compounds from a nuclear waste slurry comprising reacting a mixture of radioactive waste precipitate slurry and an acid in the presence of a catalytically effective amount of a copper(II) catalyst whereby the organic compounds in the precipitate slurry are hydrolyzed to form volatile organic compounds which are separated from the reacting mixture. The resulting waste slurry, containing less than 10 percent of the original organic compounds, is subsequently blended with high level radioactive sludge land transferred to a vitrification facility for processing into borosilicate glass for long-term storage. 2 figs., 3 tabs.

Interannual variation of annual precipitation and urban effect on precipitation in the Beijing region

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

The large scale character of the interannual variation of precipitation and the urban effect on local annual precipitation anomaly are investigated in this paper based on the 1960-2000 annual precipitation observations at 20 stations in the Beijing region. The results show that: the annual precipitation in the Beijing region possesses the large scale variation character with the linear trend of - 1.197/10 yr, which corresponds to a total reduction of 27.82 mm in annual precipitation in the 41 years; the local annual precipitation anomalies (percent of the normal 1960-2000) show a positive center near the urban area, i.e. urban precipitation island (UPI), whose intensity increases with the linear trend of 0. 6621%/10 yr, opposite to the interannual trend of large scale precipitation over the Beijing region; changes in the UPI are also associated with the intensity of synoptic processes of precipitation, and when the synoptic processes are strong (wet years), the intensity of UPI strengthens, while the synoptic processes are weak (dry years), and the UPI disappears in the Beijing region.

Production of mixed oxide fuel for fast reactor irradiation test by co-precipitation

International Nuclear Information System (INIS)

Todokoro, Akio; Masuda, Sumio; Naruki, Kaoru; Kaya, Akira; Koizumi, Masumichi

1974-01-01

Studies were made on the production of homogeneous mixed oxide by co-precipitation. Experiments were made on the effects of the addition rate of ammonia water, precipitation temperature, aging time of co-precipitate, and pH value. Plutonium refined by anion exchange was mixed with solution of uranium. The concentration of free acid in the mixed solution was adjusted to 1.5-2.0 M, and the total volume of the solution was made 3.01. The weight of Pu and U in the solution was 100g. The solution was kept at a definite temperature while being stirred. Concentrated ammonia solution was added to the solution at a definite rate. The precipitate thus formed was filtrated after aging, then dried for 24 hours at 100 +- 2 0 C. Dried co-precipitate was calcinated for 1 hr at 550 0 C. The reduction for 4 hours at 800 0 C gave the mixed powder of PuO 2 and UO 2 . After pressing, the powder was sintered for 2 hours at 1700 0 C. The shrinkage ratio decreased as the activity and tap density of the original powder increased. The activity determined by specific surface area increased as the rate of ammonia water addition increased, and as the precipitation temperature rose. Tap density was independent of the rate of addition of ammonia water. The activity of the powder increased and the tap density decreased as the aging time of precipitate increased. (Fukutomi, T.)

A facile physical approach to make chitosan soluble in acid-free water.

Science.gov (United States)

Fu, Yinghao; Xiao, Congming

2017-10-01

We changed the situation that chitosan was only dissolved in diluted acid through mild physical treatment. In viewing of the usual methods to modify chitosan are chemical ones, we established the approach by using a water-soluble chitosan derivative as the model polymer. Its water-solubility was modulated via changing the concentration of solution and varying the precipitants. Such a physical method was adopted to treat chitiosan. One gram chitosan was dissolved in a mixture of 100mL 10% acetic acid and 50mL methanol, and then precipitated from a precipitant consisted of 10mL ethanol and 90mL acetate ester. The treated chitosan became soluble in acid-free water completely, and its solubility was 8.02mg/mL. Copyright © 2017 Elsevier B.V. All rights reserved.

36 CFR 1238.5 - What publications are incorporated by reference in this part?

Science.gov (United States)

2010-07-01

... Stored Silver-Gelatin Microforms for Evidence of Deterioration, January 22, 1990, IBR approved for § 1238... Materials—Processed silver-gelatin type black-and-white films—Specifications for stability, February 15... Assurance of First-Generation, Silver Microforms of Documents, June 2, 1998, IBR approved for §§ 1238.10 and...

Treatment of acid mine wastewaters

International Nuclear Information System (INIS)

Hayward, D.; Barnard, R.

1993-01-01

Acid mine drainage often results from the oxidation sulfide minerals to form sulfuric acid. As a consequence, high concentrations of metals in the both the suspended and dissolved state result from the low pH water. This paper discusses several of the more common treatment methods for acid mine drainage including the use of chemical precipitation agents, pH correction agents, filtration methods, and biodegradation methods. Advanced treatment technologies are also briefly described and include microfiltration, reverse osmosis, ion exchange, and electrodialysis

Spent NiMH batteries-The role of selective precipitation in the recovery of valuable metals

Science.gov (United States)

Bertuol, Daniel Assumpção; Bernardes, Andréa Moura; Tenório, Jorge Alberto Soares

The production of electronic equipment, such as computers and cell phones, and, consequently, batteries, has increased dramatically. One of the types of batteries whose production and consumption has increased in recent times is the nickel metal hydride (NiMH) battery. This study evaluated a hydrometallurgical method of recovery of rare earths and a simple method to obtain a solution rich in Ni-Co from spent NiMH batteries. The active materials from both electrodes were manually removed from the accumulators and leached. Several acid and basic solutions for the recovery of rare earths were evaluated. Results showed that more than 98 wt.% of the rare earths were recovered as sulfate salts by dissolution with sulfuric acid, followed by selective precipitation at pH 1.2 using sodium hydroxide. The complete process, precipitation at pH 1.2 followed by precipitation at pH 7, removed about 100 wt.% of iron and 70 wt.% of zinc from the leaching solution. Results were similar to those found in studies that used solvent extraction. This method is easy, economic, and does not pose environmental threats of solvent extraction.

Polyamide 6/clay membranes: effect of precipitation bath in morphology

International Nuclear Information System (INIS)

Ferreira, Rodholfo da S.B.; Pereira, Caio H. do O; Leite, Amanda M.D.; Araujo, Edcleide M.; Lira, Helio L.

2015-01-01

Polyamide 6 membranes and their nanocomposites with 5% clay were obtained by the phase inversion method and the precipitation was made in distilled water bath and also in the mixture of solvent and distilled water. The nanocomposites were characterized by XRD and membranes by SEM. By XRD analysis, it was found that the obtained nanocomposite presents a structure probably exfoliated and / or partially exfoliated, it was also possible to observe the presence of two characteristic peaks (α and γ) of the polyamide 6 phases. In the SEM micrographs it was seen that the presence of clay promote alterations in morphology, size and distribution of pores. The presence of acid in the precipitation bath leads to a significant decrease in the filter layer, but also an increase in the quantity of pore size. (author)

PROCESS USING POTASSIUM LANTHANUM SULFATE FOR FORMING A CARRIER PRECIPITATE FOR PLUTONIUM VALUES

Science.gov (United States)

Angerman, A.A.

1958-10-21

A process is presented for recovering plutonium values in an oxidation state not greater than +4 from fluoride-soluble fission products. The process consists of adding to an aqueous acidic solution of such plutonium values a crystalline potassium lanthanum sulfate precipitate which carries the plutonium values from the solution.

Acid Rain: Science Projects.

Science.gov (United States)

Stubbs, Harriett S.

1989-01-01

Presented is a science activity designed to help students monitor the pH of rainfall. Materials, procedures and follow-up activities are listed. A list of domestic and foreign sources of information is provided. Topics which relate to acid precipitation are outlined. (CW)

Effective Assimilation of Global Precipitation

Science.gov (United States)

Lien, G.; Kalnay, E.; Miyoshi, T.; Huffman, G. J.

2012-12-01

Assimilating precipitation observations by modifying the moisture and sometimes temperature profiles has been shown successful in forcing the model precipitation to be close to the observed precipitation, but only while the assimilation is taking place. After the forecast start, the model tends to "forget" the assimilation changes and lose their extra skill after few forecast hours. This suggests that this approach is not an efficient way to modify the potential vorticity field, since this is the variable that the model would remember. In this study, the ensemble Kalman filter (EnKF) method is used to effectively change the potential vorticity field by allowing ensemble members with better precipitation to receive higher weights. In addition to using an EnKF, two other changes in the precipitation assimilation process are proposed to solve the problems related to the highly non-Gaussian nature of the precipitation variable: a) transform precipitation into a Gaussian distribution based on its climatological distribution, and b) only assimilate precipitation at the location where some ensemble members have positive precipitation. The idea is first tested by the observing system simulation experiments (OSSEs) using SPEEDY, a simplified but realistic general circulation model. When the global precipitation is assimilated in addition to conventional rawinsonde observations, both the analyses and the medium range forecasts are significantly improved as compared to only having rawinsonde observations. The improvement is much reduced when only modifying the moisture field with the same approach, which shows the importance of the error covariance between precipitation and all other model variables. The effect of precipitation assimilation is larger in the Southern Hemisphere than that in the Northern Hemisphere because the Northern Hemisphere analyses are already accurate as a result of denser rawinsonde stations. Assimilation of precipitation using a more comprehensive

Recovery of molybdenum using alumina microspheres and precipitation with selective organic reagents

International Nuclear Information System (INIS)

Carvalho, Fatima Maria Sequeira de; Abrao, Alcidio

1998-01-01

In this paper is presented a study for the optimization of dissolution of the UAL x plates used for irradiation and production of radiomolybdenum. The alloy is dissolved in nitric acid with mercury as catalyst. The separation and concentration of the molybdenum was achieved using a chromatographic grade alumina microspheres column. the purified eluted molybdenum is finally precipitated using one of the selective reagents: alizarine blue, α,α'- bipyridine and 1,10-phenanthroline. Any one of the obtained precipitate can be fired to the molybdenum trioxide. The interference of the following elements was studied: Re(VII), U(VI), Cr(VI), W(VI), V(V), Te(IV), Ti(IV), Zr(IV), Th(IV), Fe(III), Au(III), Ru(III), Al(III), Bi(III), Sb(III), Ce(IV), Pr(III), Sc(III), Y(III), Sm(III), Ba(II), Sr(II), Ni(II), Co(II), Cs(I). The molybdenum precipitates were characterized by gravimetric, CHN, TG, DTG, IR and X-ray diffraction analyses. (author)

Radioactive mineral spring precipitates, their analytical and statistical data and the uranium connection

Science.gov (United States)

Cadigan, R.A.; Felmlee, J.K.

1982-01-01

; (5) Hydrous limonite precipitation and coprecipitated elements including uranium; (6) Rare earth elements deposited with detrital contamination (?); (7) Metal carbonate adsorption and precipitation. Economically recoverable minerals occurring at some localities in spring precipitates are ores of iron, manganese, sulfur, tungsten and barium and ornamental travertine. Continental radioactive mineral springs occur in areas of crustal thickening caused by overthrusting of crustal plates, and intrusion and metamorphism. Sedimentary rocks on the lower plate are trapped between the plates and form a zone of metamorphism. Connate waters, carbonate rocks and organic-carbon-bearing rocks react to extreme pressure and temperature to produce carbon dioxide, and steam. Fractures are forced open by gas and fluid pressures. Deep-circulating meteoric waters then come in contact with the reactive products, and a hydrothermal cell forms. When hot mineral-charged waters reach the surface they form the familiar hot mineral springs. Hot springs also occur in relation to igneous intrusive action or volcanism both of which may be products of the crustal plate overthrusting. Uranium and thorium in the sedimentary rocks undergoing metamorphism are sometimes mobilized, but mobilization is generally restricted to an acid hydrothermal environment; much is redeposited in favorable environments in the metamorphosed sediments. Radium and radon, which are highly mobile in both acid and alkaline aqueous media move upward into the hydrothermal cell and to the surface.

Precipitation in partially stabilized zirconia

International Nuclear Information System (INIS)

Bansal, G.K.

1975-01-01

Transmission electron microscopy was used to study the substructure of partially stabilized ZrO 2 (PSZ) samples, i.e., 2-phase systems containing both cubic and monoclinic modifications of zirconia, after various heat treatments. Monoclinic ZrO 2 exists as (1) isolated grains within the polycrystalline aggregate (a grain- boundary phase) and (2) small plate-like particles within cubic grains. These intragranular precipitates are believed to contribute to the useful properties of PSZ via a form of precipitation hardening. These precipitates initially form as tetragonal ZrO 2 , with a habit plane parallel to the brace 100 brace matrix planes. The orientation relations between the tetragonal precipitates and the cubic matrix are brace 100 brace/sub matrix/ 2 parallel brace 100 brace /sub precipitate/ or (001)/sub precipitate/ and broken bracket 100 broken bracket/sub matrix/ 2 parallel broken bracket 100 broken bracket/sub precipitate/ or [001]/sub precipitate/. (U.S.)

Molecularly imprinted microspheres and nanoparticles prepared using precipitation polymerisation method for selective extraction of gallic acid from Emblica officinalis.

Science.gov (United States)

Pardeshi, Sushma; Dhodapkar, Rita; Kumar, Anupama

2014-03-01

This paper reports the preparation of gallic acid (GA) molecularly imprinted polymers (MIPs) by the precipitation polymerisation and highlights the effect of porogen on particle size and specific molecular recognition properties. MIP, M-100 prepared in the porogen acetonitrile and MIP, M-75 prepared in a mixture of acetonitrile-toluene (75:25 v/v), resulted in the formation of microspheres with approximately 4μm particle size and surface area of 96.73m(2)g(-1) and nanoparticles (0.8-1000nm) and a surface area of 345.9m(2)g(-1), respectively. The Langmuir-Freundlich isotherm study revealed that M-75 has comparatively higher number of binding sites which are homogenous and has higher affinity for GA. The MIPs selectively recognised GA in presence of its structural analogues. Pure GA with percent recovery of 75 (±1.6) and 83.4 (±2.2) was obtained from the aqueous extract of Emblica officinalis by M-100 and M-75, respectively and hot water at 60°C served as the eluting solvent. Copyright © 2013 Elsevier Ltd. All rights reserved.

The response of amino acid cycling to global change across multiple biomes: Feedbacks on soil nitrogen availability

Science.gov (United States)

Brzostek, E. R.; Finzi, A. C.

2010-12-01

The cycling of organic nitrogen (N) in soil links soil organic matter decomposition to ecosystem productivity. Amino acids are a key pool of organic N in the soil, whose cycling is sensitive to alterations in microbial demand for carbon and N. Further, the amino acids released from the breakdown of protein by proteolytic enzymes are an important source of N that supports terrestrial productivity. The objective of this study was to measure changes in amino acid cycling in response to experimental alterations of precipitation and temperature in twelve global change experiments during the 2009 growing season. The study sites ranged from arctic tundra to xeric grasslands. The treatments experimentally increased temperature, increased or decreased precipitation, or some combination of both factors. The response of amino acid cycling to temperature and precipitation manipulations tended to be site specific, but the responses could be placed into a common framework. Changes in soil moisture drove a large response in amino acid cycling. Precipitation augmentation in xeric and mesic sites increased both amino acid pool sizes and production. However, treatments that decreased precipitation drove decreases in amino acid cycling in xeric sites, but led to increases in amino acid cycling in more mesic sites. Across sites, the response to soil warming was horizon specific. Amino acid cycling in organic rich horizons responded positively to warming, while negative responses were exhibited in lower mineral soil horizons. The variable response likely reflects a higher availability of protein substrate to sustain high rates of proteolytic enzyme activity in organic rich horizons. Overall, these results suggest that soil moisture and the availability of protein substrate may be important factors that mediate the response of amino acid cycling to predicted increases in soil temperatures.

Development of radioimmunoassay for pantothenic acid in biological tissues

International Nuclear Information System (INIS)

Wyse, B.W.

1977-01-01

The purpose of this research was to develop a radioimmunoassay for quantitating pantothenic acid levels in biological tissues and to compare the new method with a microbiological procedure. Since pantothenic acid is a nonantigenic compound with a small molecular weight, it was treated as a hapten and conjugated with an immunogenic protein. A new technique for covalently linking haptens with primary alcohol groups to proteins was developed. To prepare an antiserum for the radioimmunoassay, pantothenic acid-bovine serum albumin antigen was injected into the foot pads of rabbits. As antibodies to pantothenic acid hapten were elicited they were characterized using three classical techniques: ring precipitant test, gel diffusion (Ouchterlony), and skin test (Arthus). For the radioimmunoassay an appropriate dilution of antiserum was incubated in the presence of tritium labeled pantothenic acid and non-radioactive pantothenic acid for the standard curve or tissue extracts containing pantothenic acid. After incubation overnight, the antibodies were precipitated and solubilized and the radioactivity was counted in a liquid scintillation counter. Blood pantothenic acid levels of sixty-eight senior citizens were determined by the radioimmunoassay and by microbiological assay with Lactobacillus plantarum. A highly significant correlation was found between the two assays

Radioimmunoassay of conjugated cholic acid, chenodeoxycholic acid, and deoxycholic acid from human serum, with use of 125I-labeled ligands

International Nuclear Information System (INIS)

Maeentausta, O.; Jaenne, O.

1979-01-01

We describe a method for radioimmunoassay of conjugated cholic acid, chenodeoxycholic acid, and deoxycholic acid in serum. In the method, 125 I-labeled bile acid conjugates are used as the tracers along with antibodies raised against individual bile acid-bovine serum albumin conjugates. Antibody-bound and free bile acids were separated by polyethylene glycol precipitation (final concentration, 125 g/L). The lowest measurable amounts of the bile acids, expressed as pmol/tube, were: cholic acid conjugates, 2; chenodeoxycholic acid conjugates, 0.5; and deoxycholic acid conjugates, 2. Analytical recovery of bile acids added to bile acid-free serum ranged from 85 to 110%; intra-assay and inter-assay CVs ranged from 8.3 to 5.3% and from 5.3 to 12.2%, respectively. Concentrations (mean +- SD) of the bile acid conjugates in serum from apparently healthy women and men (in μmol/L) were: cholic acid conjugates, 0.43 +- 0.17 (n=126); chenodeoxycholic acid conjugates, 0.47 +- 0.23 (n=111); and deoxycholic acid conjugates, 0.33 +- 0.11 (n=96). The values for primary bile acids were greatly increased in patients with various hepatobiliary diseases

Biochemical process for the removal of uranium from acid mine drainages

International Nuclear Information System (INIS)

Roig, M.G.; Manzano, T.; Diaz, M.

1997-01-01

A biochemical process has been assessed with a view to removing heavy metals from acid mine drainages in which the metal cation removed is accumulated in situ as insoluble metal phosphate on the surface of Citrobacter N 14 cells (Roig et al., 1995). The localized presence of inorganic phosphate (P i ) is brought about via the hydrolysis of a ''donor'' organic phosphate added to the solution of metals with precipitation as MHPO 4 bound to the cells. The present work explores the potential of immobilized Citrobacter biomass for the recovery of uranium from the acid drainage waters of the ''Faith'' mine exploited by ENUSA (Ciudad Rodrigo, Salamanca). A physicochemical characterization of the acid waste-water from ENUSA was carried out and flow injection analysis methods for the determination of uranium and P i in such water were developed and improved. The efficiencies of chemical precipitation (by the addition of P i to the acid water) with regard to bioinsolubilization (supplementing the water with an organic phosphate that is (later) hydrolysed to P i ) were investigated and compared. Additionally, the efficiency of chemical and biochemical precipitation as phosphates of uranium present in ENUSA acid drainage water were assessed. Furthermore, the relative importance of chemical precipitation (by the addition of P i to the acid water) with regard to bioinsolubilization (supplementing the water with an organic phosphate that is (later) hydrolysed to P i plus alcohol) was established. To do so, a series of mass balances for chemical precipitation and for bioinsolubilization of the metal phosphate was performed. Once the efficiency of the bioprocess as regards the removal of uranium when glycerol-2-phosphate is used as a substrate had been determined, a major question was forthcoming: the search for an efficient and much more economical substrate for the process. In this sense, sodium tripolyphosphate, one of the main components of many formulations of commercial

Precipitation of {gamma}' phase in {delta}-precipitated Alloy 718 during deformation at elevated temperatures

Energy Technology Data Exchange (ETDEWEB)

Nalawade, S.A. [Structural Metallurgy Section, Mechanical Metallurgy Section, Bhabha Atomic Research Centre, Mumbai 400085 (India); Sundararaman, M., E-mail: msraman@barc.gov.in [Structural Metallurgy Section, Mechanical Metallurgy Section, Bhabha Atomic Research Centre, Mumbai 400085 (India); Singh, J.B.; Verma, A.; Kishore, R. [Structural Metallurgy Section, Mechanical Metallurgy Section, Bhabha Atomic Research Centre, Mumbai 400085 (India)

2010-05-15

Alloy 718 samples aged to precipitate only {delta} particles (with maximum volume fraction) when tensile deformed to fracture at elevated temperatures revealed precipitation of {gamma}' and {gamma}'' phases. The {gamma}' precipitation was found to precede the {gamma}'' phase precipitation unlike in the case of specimens subjected to standard ageing treatment where both the {gamma}' and the {gamma}'' phases precipitate simultaneously. This sequence is explained on the basis of the relative concentration of Al, Ti and Nb in the matrix of {delta} precipitated Alloy 718 microstructure. The precipitation sequence was consistent with the Cozar and Pineau's model that predicts such sequences on the basis of (Al + Ti) to Nb atom ratios.

Dependence of precipitation of trace elements on pH in standard water

Science.gov (United States)

Verma, Shivcharan; Mohanty, Biraja P.; Singh, K. P.; Behera, B. R.; Kumar, Ashok

2018-04-01

The present work aimed to study the dependence of precipitation of trace elements on the pH of solution. A standard solution was prepared by using ultrapure deionized water (18.2 MΩ/cm) as the solvent and 11 water-soluble salts having different elements as solutes. Five samples of different pH values (2 acidic, 2 basic, and 1 neutral) were prepared from this standard solution. Sodium-diethyldithiocarbamate was used as the chelating agent to precipitate the metal ions present in these samples of different pH values. The targets were prepared by collecting these precipitates on mixed cellulose esters filter of 0.4 μm pore size by vacuum filtration. Elemental analysis of these targets was performed by particle-induced X-ray emission (PIXE) using 2.7 MeV protons from the single Dee variable energy cyclotron at Panjab University, Chandigarh, India. PIXE data were analyzed using GUPIXWIN software. For most of the elements, except Hg with oxidation state +2, such as Co, Ni, Zn, Ba, and Cd, a general trend of enhancement in precipitation was observed with the increase in pH. However, for other elements such as V, As, Mo, Ag, and Bi, which have oxidation state other than +2, no definite pattern was observed. Precipitation of Ba and As using this method was negligible at all five pH values. From these results, it can be concluded that the precipitation and recovery of elements depend strongly on the pH of the water sample.

Development of polymeric nanoparticles showing tuneable pH-responsive precipitation

Energy Technology Data Exchange (ETDEWEB)

Vakurov, Alexander, E-mail: a.v.vakourov@bmb.leeds.ac.uk; Pchelintsev, Nikolay A., E-mail: n.a.pchelintsev@googlemail.com; Gibson, Tim, E-mail: timdgibson@merchab.fsnet.co.uk; Millner, Paul, E-mail: p.a.millner@leeds.ac.uk [Research Institute of Membrane and Systems Biology, University of Leeds (United Kingdom)

2012-12-15

A reverse micellar system comprising dioctyl-sulfosuccinate (AOT)/toluene was used as a template for polymerization of acrylamide/bisacrylamide-based functionalized polymeric nanoparticles. Such nanoparticles were typically sized between 20 and 90 nm and could be synthesized with a wide range of functional groups according to the monomers added to the polymerization mixture. Carboxy nanoparticles with acrylic acid as the functional monomer were synthesized in the reported work. The carboxy nanoparticles were pH sensitive and precipitated at pHs below 4. Modification of carboxy-functionalized polymeric nanoparticles with polyetheleneimine (PEI) resulted in the fabrication of a series of pH-responsive nanoparticles which could precipitate at different pHs and ionic strengths according to the PEI/carboxy ratio in the system. Both non-covalent PEI-nanoparticles conjugates and nanoparticles with covalently linked PEI behaved in this way.

Development of polymeric nanoparticles showing tuneable pH-responsive precipitation

International Nuclear Information System (INIS)

Vakurov, Alexander; Pchelintsev, Nikolay A.; Gibson, Tim; Millner, Paul

2012-01-01

A reverse micellar system comprising dioctyl-sulfosuccinate (AOT)/toluene was used as a template for polymerization of acrylamide/bisacrylamide-based functionalized polymeric nanoparticles. Such nanoparticles were typically sized between 20 and 90 nm and could be synthesized with a wide range of functional groups according to the monomers added to the polymerization mixture. Carboxy nanoparticles with acrylic acid as the functional monomer were synthesized in the reported work. The carboxy nanoparticles were pH sensitive and precipitated at pHs below 4. Modification of carboxy-functionalized polymeric nanoparticles with polyetheleneimine (PEI) resulted in the fabrication of a series of pH-responsive nanoparticles which could precipitate at different pHs and ionic strengths according to the PEI/carboxy ratio in the system. Both non-covalent PEI-nanoparticles conjugates and nanoparticles with covalently linked PEI behaved in this way.

Few multiyear precipitation-reduction experiments find a shift in the productivity-precipitation relationship.

Science.gov (United States)

Estiarte, Marc; Vicca, Sara; Peñuelas, Josep; Bahn, Michael; Beier, Claus; Emmett, Bridget A; Fay, Philip A; Hanson, Paul J; Hasibeder, Roland; Kigel, Jaime; Kröel-Dulay, Gyorgy; Larsen, Klaus Steenberg; Lellei-Kovács, Eszter; Limousin, Jean-Marc; Ogaya, Romà; Ourcival, Jean-Marc; Reinsch, Sabine; Sala, Osvaldo E; Schmidt, Inger Kappel; Sternberg, Marcelo; Tielbörger, Katja; Tietema, Albert; Janssens, Ivan A

2016-07-01

Well-defined productivity-precipitation relationships of ecosystems are needed as benchmarks for the validation of land models used for future projections. The productivity-precipitation relationship may be studied in two ways: the spatial approach relates differences in productivity to those in precipitation among sites along a precipitation gradient (the spatial fit, with a steeper slope); the temporal approach relates interannual productivity changes to variation in precipitation within sites (the temporal fits, with flatter slopes). Precipitation-reduction experiments in natural ecosystems represent a complement to the fits, because they can reduce precipitation below the natural range and are thus well suited to study potential effects of climate drying. Here, we analyse the effects of dry treatments in eleven multiyear precipitation-manipulation experiments, focusing on changes in the temporal fit. We expected that structural changes in the dry treatments would occur in some experiments, thereby reducing the intercept of the temporal fit and displacing the productivity-precipitation relationship downward the spatial fit. The majority of experiments (72%) showed that dry treatments did not alter the temporal fit. This implies that current temporal fits are to be preferred over the spatial fit to benchmark land-model projections of productivity under future climate within the precipitation ranges covered by the experiments. Moreover, in two experiments, the intercept of the temporal fit unexpectedly increased due to mechanisms that reduced either water loss or nutrient loss. The expected decrease of the intercept was observed in only one experiment, and only when distinguishing between the late and the early phases of the experiment. This implies that we currently do not know at which precipitation-reduction level or at which experimental duration structural changes will start to alter ecosystem productivity. Our study highlights the need for experiments with

Procedure for reducing hydrogen ion concentration in acidic anion eluate

International Nuclear Information System (INIS)

Parobek, P.; Baloun, S.; Plevac, S.

1992-01-01

A procedure is suggested for reducing the concentration of hydrogen ions in the acidic anionic eluate formed during the separation of uranium. The procedure involves anex elution, precipitation, filtration, precipitate rinsing, and anex rinsing. The procedure is included in the uranium elution process and requires at least one ion exchanger column and at least one tank in the continuous or discontinuous mode. Sparing the neutralizing agent by reducing the hydrogen ion concentration in the acidic anionic eluate is a major asset of this procedure. (Z.S.). 1 fig

A GC-ECD method for estimation of free and bound amino acids, gamma-aminobutyric acid, salicylic acid, and acetyl salicylic acid from Solanum lycopersicum (L.).

Science.gov (United States)

Meher, Hari Charan; Gajbhiye, Vijay T; Singh, Ghanendra

2011-01-01

A gas chromatograph with electron capture detection method for estimation of selected metabolites--amino acids (free and bound), gamma-aminobutyric acid (GABA), salicylic acid (SA), and acetyl salicylic acid (ASA) from tomato--is reported. The method is based on nitrophenylation of the metabolites by 1-fluoro-2, 4-dinitrobenzene under aqueous alkaline conditions to form dinitophenyl derivatives. The derivatives were stable under the operating conditions of GC. Analysis of bound amino acids comprised perchloric acid precipitation of protein, alkylation (carboxymethylation) with iodoacetic acid, vapor-phase hydrolysis, and derivatization with 1-fluoro-2,4-dinitrobenzene in that order. The metabolites were resolved in 35 min, using a temperature-programmed run. The method is rapid, sensitive, and precise. It easily measured the typical amino acids (aspartate, asparagine, glutamate, glutamine, alanine, leucine, lysine, and phenylalanine) used for identification and quantification of a protein, resolved amino acids of the same mass (leucine and isoleucine), satisfactorily measured sulfur amino acid (methionine, cystine, and cysteine), and quantified GABA, SA, and ASA, as well. The developed method was validated for specificity, linearity, and precision. It has been applied and recommended for estimation of 25 metabolites from Solanum lycopersicum (L.).

Similarities and Improvements of GPM Dual-Frequency Precipitation Radar (DPR upon TRMM Precipitation Radar (PR in Global Precipitation Rate Estimation, Type Classification and Vertical Profiling

Directory of Open Access Journals (Sweden)

Jinyu Gao

2017-11-01

Full Text Available Spaceborne precipitation radars are powerful tools used to acquire adequate and high-quality precipitation estimates with high spatial resolution for a variety of applications in hydrological research. The Global Precipitation Measurement (GPM mission, which deployed the first spaceborne Ka- and Ku-dual frequency radar (DPR, was launched in February 2014 as the upgraded successor of the Tropical Rainfall Measuring Mission (TRMM. This study matches the swath data of TRMM PR and GPM DPR Level 2 products during their overlapping periods at the global scale to investigate their similarities and DPR’s improvements concerning precipitation amount estimation and type classification of GPM DPR over TRMM PR. Results show that PR and DPR agree very well with each other in the global distribution of precipitation, while DPR improves the detectability of precipitation events significantly, particularly for light precipitation. The occurrences of total precipitation and the light precipitation (rain rates < 1 mm/h detected by GPM DPR are ~1.7 and ~2.53 times more than that of PR. With regard to type classification, the dual-frequency (Ka/Ku and single frequency (Ku methods performed similarly. In both inner (the central 25 beams and outer swaths (1–12 beams and 38–49 beams of DPR, the results are consistent. GPM DPR improves precipitation type classification remarkably, reducing the misclassification of clouds and noise signals as precipitation type “other” from 10.14% of TRMM PR to 0.5%. Generally, GPM DPR exhibits the same type division for around 82.89% (71.02% of stratiform (convective precipitation events recognized by TRMM PR. With regard to the freezing level height and bright band (BB height, both radars correspond with each other very well, contributing to the consistency in stratiform precipitation classification. Both heights show clear latitudinal dependence. Results in this study shall contribute to future development of spaceborne

Two-stage precipitation of plutonium trifluoride

International Nuclear Information System (INIS)

Luerkens, D.W.

1984-04-01

Plutonium trifluoride was precipitated using a two-stage precipitation system. A series of precipitation experiments identified the significant process variables affecting precipitate characteristics. A mathematical precipitation model was developed which was based on the formation of plutonium fluoride complexes. The precipitation model relates all process variables, in a single equation, to a single parameter that can be used to control particle characteristics

A new method for the homogeneous precipitative separation of trace level lanthanides as oxalates: application to different types of geological samples

International Nuclear Information System (INIS)

Premadas, A.; Cyriac, Bincy; Kesavan, V.S.

2013-01-01

Oxalate precipitation of lanthanides in acidic medium is a widely used selective group separation method at percentage to trace level in different types of geological samples. Most of the procedures are based on the heterogeneous oxalate precipitation of lanthanides using calcium as carrier. In the heterogeneous precipitation, the co-precipitated impurities from the matrix elements are more, besides if the pH at the time of precipitation is not monitored carefully there is a chance of losing some of the lanthanides. In this report, we present a new homogeneous oxalate precipitation of trace level lanthanides from different types of geological samples using calcium as carrier. In the present method pH is getting adjusted (pH ∼1) on its own, after the hydrolysis of urea added to the sample solution. This acidic pH is essential for the complete precipitation of the lanthanides. Therefore, no critical parameter adjustment for the precipitation is involved in the proposed method. The oxalate precipitate obtained was in crystalline nature which facilitates the fast settlement, easy filtration; besides the co-precipitated matrix elements are very less as compared to normal heterogeneous oxalate precipitation of lanthanides. Another advantage is more quantity of the sample can be taken for the separation of lanthanides which is a limitation for other separation methods reported. Accuracy of the method was checked by analyzing nine international reference materials comprising different types of geological samples obtained from Canadian Certified Reference Project Materials such as syenite samples SY-2, SY-3 and SY-4; gabro sample MRG-1; soil samples SO-1 and SO-2; iron formation sample FeR-2; lake sediments LKSD-2 and LKSD-4. The values of the lanthanides obtained for these reference materials are comparable with recommended values, indicating that the method is accurate. The reproducibility is characterized by a relative standard deviation (RSD) of 1 to 6% (n=4). (author)

Global Precipitation Measurement (GPM) Mission: Precipitation Processing System (PPS) GPM Mission Gridded Text Products Provide Surface Precipitation Retrievals

Science.gov (United States)

Stocker, Erich Franz; Kelley, O.; Kummerow, C.; Huffman, G.; Olson, W.; Kwiatkowski, J.

2015-01-01

In February 2015, the Global Precipitation Measurement (GPM) mission core satellite will complete its first year in space. The core satellite carries a conically scanning microwave imager called the GPM Microwave Imager (GMI), which also has 166 GHz and 183 GHz frequency channels. The GPM core satellite also carries a dual frequency radar (DPR) which operates at Ku frequency, similar to the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar, and a new Ka frequency. The precipitation processing system (PPS) is producing swath-based instantaneous precipitation retrievals from GMI, both radars including a dual-frequency product, and a combined GMIDPR precipitation retrieval. These level 2 products are written in the HDF5 format and have many additional parameters beyond surface precipitation that are organized into appropriate groups. While these retrieval algorithms were developed prior to launch and are not optimal, these algorithms are producing very creditable retrievals. It is appropriate for a wide group of users to have access to the GPM retrievals. However, for researchers requiring only surface precipitation, these L2 swath products can appear to be very intimidating and they certainly do contain many more variables than the average researcher needs. Some researchers desire only surface retrievals stored in a simple easily accessible format. In response, PPS has begun to produce gridded text based products that contain just the most widely used variables for each instrument (surface rainfall rate, fraction liquid, fraction convective) in a single line for each grid box that contains one or more observations.This paper will describe the gridded data products that are being produced and provide an overview of their content. Currently two types of gridded products are being produced: (1) surface precipitation retrievals from the core satellite instruments GMI, DPR, and combined GMIDPR (2) surface precipitation retrievals for the partner constellation

Recovery of vanadium (V) from spent catalysts used in sulfuric acid production units by acid or alkaline leaching

International Nuclear Information System (INIS)

Abdulbaki, M.; Stas, J.; Shino, O.; Asaad, K.; Al-Kassemi, H.; Al-Qabani, F.

2008-01-01

The present paper, studies the recovery of vanadium from the spent catalyst by using acidic or alkaline leaching technique. The optimal conditions of spent catalyst leaching have been studied. It has been shown that 20%(w/w) of sulfuric acid is the most suitable for leaching process at 70 Centigrade. The precipitation of vanadium using some alkaline media (Na 2 CO 3 , (NH 4 )CO 3 and NH 4 OH) has been also studied, it has been shown that ammonium hydroxide was the best at 60 degree, and iron was co-precipitated with vanadium which pollute the obtained red cake. So it is necessary to use liquid-liquid extraction technique for the separation between vanadium and iron and to have iron free red cake. (author)

Detoxification of Sap from Felled Oil Palm Trunks for the Efficient Production of Lactic Acid.

Science.gov (United States)

Kunasundari, Balakrishnan; Arai, Takamitsu; Sudesh, Kumar; Hashim, Rokiah; Sulaiman, Othman; Stalin, Natra Joseph; Kosugi, Akihiko

2017-09-01

The availability of fermentable sugars in high concentrations in the sap of felled oil palm trunks and the thermophilic nature of the recently isolated Bacillus coagulans strain 191 were exploited for lactic acid production under non-sterile conditions. Screening indicated that strain 191 was active toward most sugars including sucrose, which is a major component of sap. Strain 191 catalyzed a moderate conversion of sap sugars to lactic acid (53%) with a productivity of 1.56 g/L/h. Pretreatment of oil palm sap (OPS) using alkaline precipitation improved the sugar fermentability, providing a lactic acid yield of 92% and productivity of 2.64 g/L/h. To better characterize potential inhibitors in the sap, phenolic, organic, and mineral compounds were analyzed using non-treated sap and saps treated with activated charcoal and alkaline precipitation. Phthalic acid, 3,4-dimethoxybenzoic acid, aconitic acid, syringic acid, and ferulic acid were reduced in the sap after treatment. High concentrations of Mg, P, K, and Ca were also precipitated by the alkaline treatment. These results suggest that elimination of excess phenolic and mineral compounds in OPS can improve the fermentation yield. OPS, a non-food resource that is readily available in bulk quantities from plantation sites, is a promising source for lactic acid production.

Separation of aromatic precipitates from simulated high level radioactive waste by hydrolysis, evaporation and liquid-liquid extraction

International Nuclear Information System (INIS)

Young, S.R.; Shah, H.B.; Carter, J.T.

1991-01-01

The Defense Waste Processing Facility (DWPF) at the SRS will be the United States' first facility to process High Level radioactive Waste (HLW) into a borosilicate glass matrix. The removal of aromatic precipitates by hydrolysis, evaporation and liquid-liquid extraction will be a key step in the processing of the HLW. This step, titled the Precipitate Hydrolysis Process, has been demonstrated by the Savannah River Laboratory with the Precipitate Hydrolysis Experimental Facility (PHEF). The mission of the PHEF is to demonstrate processing of simulated high level radioactive waste which contains tetraphenylborate precipitates and nitrite. Reduction of nitrite by hydroxylamine nitrate and hydrolysis of the tetraphenylborate by formic acid is discussed. Gaseous production, which is primarily benzene, nitrous oxide and carbon dioxide, has been quantified. Production of high-boiling organic compounds and the accumulation of these organic compounds within the process are addressed

Acidity of vapor plume from cooling tower mixed with flue gases emitted from coal-fired power plant.

Science.gov (United States)

Hlawiczka, Stanislaw; Korszun, Katarzyna; Fudala, Janina

2016-06-01

Acidity of products resulting from the reaction of flue gas components emitted from a coal-fired power plant with water contained in a vapor plume from a wet cooling tower was analyzed in a close vicinity of a power plant (710 m from the stack and 315 m from the cooling tower). Samples of this mixture were collected using a precipitation funnel where components of the mixed plumes were discharged from the atmosphere with the rainfall. To identify situations when the precipitation occurred at the same time as the wind directed the mixed vapor and flue gas plumes above the precipitation funnel, an ultrasound anemometer designed for 3D measurements of the wind field located near the funnel was used. Precipitation samples of extremely high acidity were identified - about 5% of samples collected during 12 months showed the acidity below pH=3 and the lowest recorded pH was 1.4. During the measurement period the value of pH characterizing the background acidity of the precipitation was about 6. The main outcome of this study was to demonstrate a very high, and so far completely underestimated, potential of occurrence of episodes of extremely acid depositions in the immediate vicinity of a coal-fired power plant. Copyright © 2016 Elsevier B.V. All rights reserved.

Probability of occurrence of monthly and seasonal winter precipitation over Northwest India based on antecedent-monthly precipitation

Science.gov (United States)

Nageswararao, M. M.; Mohanty, U. C.; Dimri, A. P.; Osuri, Krishna K.

2018-05-01

Winter (December, January, and February (DJF)) precipitation over northwest India (NWI) is mainly associated with the eastward moving mid-latitude synoptic systems, western disturbances (WDs), embedded within the subtropical westerly jet (SWJ), and is crucial for Rabi (DJF) crops. In this study, the role of winter precipitation at seasonal and monthly scale over NWI and its nine meteorological subdivisions has been analyzed. High-resolution (0.25° × 0.25°) gridded precipitation data set of India Meteorological Department (IMD) for the period of 1901-2013 is used. Results indicated that the seasonal precipitation over NWI is below (above) the long-term mean in most of the years, when precipitation in any of the month (December/January/February) is in deficit (excess). The contribution of December precipitation (15-20%) to the seasonal (DJF) precipitation is lesser than January (35-40%) and February (35-50%) over all the subdivisions. December (0.60), January (0.57), and February (0.69) precipitation is in-phase (correlation) with the corresponding winter season precipitation. However, January precipitation is not in-phase with the corresponding December (0.083) and February (-0.03) precipitation, while December is in-phase with the February (0.21). When monthly precipitation (December or January or December-January or February) at subdivision level over NWI is excess (deficit); then, the probability of occurrence of seasonal excess (deficit) precipitation is high (almost nil). When antecedent-monthly precipitation is a deficit or excess, the probability of monthly (January or February or January + February) precipitation to be a normal category is >60% over all the subdivisions. This study concludes that the December precipitation is a good indicator to estimate the performance of January, February, January-February, and the seasonal (DJF) precipitation.

An Improved Plutonium Trifluoride Precipitation Flowsheet

Energy Technology Data Exchange (ETDEWEB)

Harmon, H.D.

2001-06-26

This report discusses results of the plutonium trifluoride two-stage precipitation study. A series of precipitation experiments was used to identify the significant process variables affecting precipitation performance. A mathematical model of the precipitation process was developed which is based on the formation of plutonium fluoride complexes. The precipitation model relates all process variables, in a single equation, to a single parameter which can be used to control the performance of the plutonium trifluoride precipitation process. Recommendations have been made which will optimize the FB-Line plutonium trifluoride precipitation process.

An Improved Plutonium Trifluoride Precipitation Flowsheet

International Nuclear Information System (INIS)

Harmon, H.D.

2001-01-01

This report discusses results of the plutonium trifluoride two-stage precipitation study. A series of precipitation experiments was used to identify the significant process variables affecting precipitation performance. A mathematical model of the precipitation process was developed which is based on the formation of plutonium fluoride complexes. The precipitation model relates all process variables, in a single equation, to a single parameter which can be used to control the performance of the plutonium trifluoride precipitation process. Recommendations have been made which will optimize the FB-Line plutonium trifluoride precipitation process

Two-step process of regeneration of acid(s) from ZrF{sub 4} containing spent pickle liquor and recovery of zirconium metal

Energy Technology Data Exchange (ETDEWEB)

Nersisyan, Hayk [Graduate School of Department of Materials Science & Engineering, Chungnam National University, 99 Daehakro, Yuseong-gu, Daejeon (Korea, Republic of); RASOM, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon (Korea, Republic of); Han, Seul Ki; Choi, Jeong Hun [Graduate School of Department of Materials Science & Engineering, Chungnam National University, 99 Daehakro, Yuseong-gu, Daejeon (Korea, Republic of); Graduate School of Energy Science & Technology, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon (Korea, Republic of); Lee, Young-Jun; Yoo, Bung Uk [Graduate School of Energy Science & Technology, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon (Korea, Republic of); Ri, Vladislav E. [Graduate School of Department of Materials Science & Engineering, Chungnam National University, 99 Daehakro, Yuseong-gu, Daejeon (Korea, Republic of); Lee, Jong Hyeon, E-mail: jonglee@cnu.ac.kr [Graduate School of Department of Materials Science & Engineering, Chungnam National University, 99 Daehakro, Yuseong-gu, Daejeon (Korea, Republic of); Graduate School of Energy Science & Technology, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon (Korea, Republic of); RASOM, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon (Korea, Republic of)

2017-04-01

In this paper we describe a progressive two-step process that allows zirconium fluoride (ZrF{sub 4}) contained in spent baths for etched zirconium alloys to be effectively recycled on a pilot scale and produce a high purity regenerated pickling acid. In the first step, a spent pickling liquor is treated by a BaF{sub 2} suspension to produce water insoluble Ba{sub 2}ZrF{sub 8}. After filtration of Ba{sub 2}ZrF{sub 8} more than 99.9 wt % purity pickling acid is regenerated. The precipitation mechanism of Ba{sub 2}ZrF{sub 8} is discussed and the role of BaF{sub 2} particles size on the precipitation process is demonstrated. In the second step the as-precipitated Ba{sub 2}ZrF{sub 8} is mixed with Mg and Cu metal powders and heat-treated at 1200 °C (or above) to produce CuZr alloy ingot. The characteristics of the ingot are discussed in regard to Cu concentration and the heating temperature. - Highlights: •Two-step process for recycling ZrF{sub 4} containing pickling acid on a pilot scale is developed. •Water insoluble Ba{sub 2}ZrF{sub 8} is precipitated by mixing spent pickling liquor with BaF{sub 2}. •The recycled pickling acid demonstrates more than 99.9 wt % purity. •The processing of Ba{sub 2}ZrF{sub 8} with Cu and Mg metals at 1200 °C yielded CuZr alloy. •The recovery depth of Zr was more than 95 wt%.

Cryophenomena in the Cold Desert of Atacama

Science.gov (United States)

Buchroithner, Dr.; Trombotto, Dr.

2012-04-01

The study area of the Valle de Barrancas Blancas in the High Atacama Andes of Chile (68°39' W, 27°02' S), a kind of Patagonian "bajo sin salida", shows well preserved landforms resulting from a combination of slope, eolian, lacustrine/litoral, fluvial, glacial and periglacial regimes. They permit the reconstruction of geomorphological processes within this isolated catchment of approximately 160 km2. The mean annual air temperature varies between -2 and -4 °C and the precipitation is approximately 150 mm/a. Snowfall is frequent but the snow is quickly sublimated, redeposited and/or covered by cryosediments, i.e. mainly pumice pebbles. Water bodies present icings, even in summer. Regarding its climatic conditions the study area represents an extremely cold desertic region. Extremophile microfauna was also found. The area displays both in situ mountain permafrost and creeping permafrost. The active layer is 30 to 45 cm thick. It is a periglacial macro-environment where interdependent processes, and not only cryogenic processes but also erosion and eolian deposition and the action of fluvial washout mainly caused by precipitation, accumulation, retransportation/redeposition and melting of snow, play an important role. The cryogenic geomorphology of the Valle de Barrancas Blancas is varied and contains microforms such as patterned ground and microforms caused by cryoturbation, as well as mesoforms like rockglaciers and cryoplanation surfaces. Slopes are strongly affected by gelifluction. New cryoforms in South America and in the Southern Hemisphere like the Atacama Pingo (Pingo atacamensis) and Permafrosted Dunes ("Dunas heladas") were found. Intense niveo-eolian processes participate in the erosion of preexisting landforms, in the formation of subterraneous ice layers, and the retransportation/redeposition of snow and sediments. Studies of this periglacial environment are crucial for the understanding of Tundrean paleoenvironments and Martian conditions.

Acidity in rainfall

International Nuclear Information System (INIS)

Tisue, G.T.; Kacoyannakis, J.

1975-01-01

The reported increasing acidity of rainfall raises many interesting ecological and chemical questions. In spite of extensive studies in Europe and North America there are, for example, great uncertainties in the relative contributions of strong and weak acids to the acid-base properties of rainwater. Unravelling this and similar problems may require even more rigorous sample collection and analytical procedures than previously employed. Careful analysis of titration curves permits inferences to be made regarding chemical composition, the possible response of rainwater to further inputs of acidic components to the atmosphere, and the behavior to be expected when rainwater interacts with the buffers present in biological materials and natural waters. Rainwater samples collected during several precipitation events at Argonne National Laboratory during October and November 1975 have been analyzed for pH, acid and base neutralizing properties, and the ions of ammonium, nitrate, chloride, sulfate, and calcium. The results are tabulated

Optimization of process parameters in precipitation for consistent quality UO2 powder production

International Nuclear Information System (INIS)

Tiwari, S.K.; Reddy, A.L.V.; Venkataswamy, J.; Misra, M.; Setty, D.S.; Sheela, S.; Saibaba, N.

2013-01-01

Nuclear reactor grade natural uranium dioxide powder is being produced through precipitation route, which is further processed before converting into sintered pellets used in the fabrication of PHWR fuel assemblies of 220 and 540 MWe type reactors. The process of precipitating Uranyl Nitrate Pure Solution (UNPS) is an important step in the UO 2 powder production line, where in soluble uranium is transformed into solid form of Ammonium Uranate (AU), which in turn reflects and decides the powder characteristics. Precipitation of UNPS with vapour ammonia is being carried out in semi batch process and process parameters like ammonia flow rate, temperature, concentration of UNPS and free acidity of UNPS are very critical and decides the UO 2 powder quality. Variation in these critical parameters influences powder characteristics, which in turn influences the sinterability of UO 2 powder. In order to get consistent powder quality and sinterability the critical parameter like ammonia flow rate during precipitation is studied, optimized and validated. The critical process parameters are controlled through PLC based automated on-line data acquisition systems for achieving consistent powder quality with increased recovery and production. The present paper covers optimization of process parameters and powder characteristics. (author)

Radar-Derived Quantitative Precipitation Estimation Based on Precipitation Classification

Directory of Open Access Journals (Sweden)

Lili Yang

2016-01-01

Full Text Available A method for improving radar-derived quantitative precipitation estimation is proposed. Tropical vertical profiles of reflectivity (VPRs are first determined from multiple VPRs. Upon identifying a tropical VPR, the event can be further classified as either tropical-stratiform or tropical-convective rainfall by a fuzzy logic (FL algorithm. Based on the precipitation-type fields, the reflectivity values are converted into rainfall rate using a Z-R relationship. In order to evaluate the performance of this rainfall classification scheme, three experiments were conducted using three months of data and two study cases. In Experiment I, the Weather Surveillance Radar-1988 Doppler (WSR-88D default Z-R relationship was applied. In Experiment II, the precipitation regime was separated into convective and stratiform rainfall using the FL algorithm, and corresponding Z-R relationships were used. In Experiment III, the precipitation regime was separated into convective, stratiform, and tropical rainfall, and the corresponding Z-R relationships were applied. The results show that the rainfall rates obtained from all three experiments match closely with the gauge observations, although Experiment II could solve the underestimation, when compared to Experiment I. Experiment III significantly reduced this underestimation and generated the most accurate radar estimates of rain rate among the three experiments.

Contribution to the study of urano-vanadates: precipitation, stability, and filiation; Contribution a l'etude des uranivanadates: precipitation, stabilite et filiation

Energy Technology Data Exchange (ETDEWEB)

Nicole, J [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1969-07-01

The interaction of uranyl ions with vanadic anhydride leads to the formation of different uranium vanadates according to which uranyl salt is used. With uranyl perchlorate solutions, urano-tri-meta-vanadic acid H[UO{sub 2}(VO{sub 3}){sub 3}] precipitates, and the excess uranyl ions then replace the H to give UO{sub 2}[UO{sub 2}(VO{sub 3}){sub 3}]{sub 2}. The addition of vanadic anhydride solution leads to the same compounds, although in this case there is prior formation of UO{sub 2}[UO{sub 2}(OH){sub 2}VO{sub 3}]{sub 2}. Uranyl acetate on the other hand gives successively and quantitatively the acids H[UO{sub 2}(VO{sub 3}){sub 3}], H[UO{sub 2}(OH)VO{sub 3}], and H[UO{sub 2}(OH){sub 2}VO{sub 3}] and then the uranyl salt of this latter compound; the order in which the reagents are added is of no importance. The composition of the uranium vanadates obtained by interaction of solutions of uranyl perchlorate and of the various vanadates depends on the ratio Na{sub 2}O/V{sub 2}O{sub 5} of the vanadates considered. For ratios of less than unity, derivatives of urano-tri-meta-vanadic acid are almost exclusively formed. For ratios equal to 3, the compounds are derivatives of urano-meta-vanadic acid. In between these two ratios, the compounds are derivatives of both acids simultaneously. The changes in these compounds with changing pH confirm these results. (author) [French] L'interaction des ions uranyles et de l'anhydride vanadique conduit a la formation de divers uranivanadates suivant le sel d'uranyle utilise. Avec les solutions de perchlorate d'uranyle, l'acide uranitrimetavanadique H[UO{sub 2}(VO{sub 3}){sub 3}] precipite puis les ions uranyles en exces se substituent a H pour donner UO{sub 2}[UO{sub 2}(VO{sub 3}){sub 3}]{sub 2}. L'addition de solution d'anhydride vanadique conduit aux memes composes avec toutefois une formation preliminaire de UO{sub 2}[UO{sub 2}(OH){sub 2}VO{sub 3}]{sub 2}. Au contraire, l'acetate d'uranyle fournit successivement et quantitativement

Precipitation Sedimentation and Advection in GFS

Science.gov (United States)

Sun, R.; Tallapragada, V.

2016-12-01

Zhao and Carr microphysics scheme as implemented in the NCEP Global Forecasting System (GFS) predicts only the total cloud condensate (cloud water or ice). The precipitation generated in the column fall to the ground instantly. This mean precipitation sedimentation and advection are not considered. As resolution increases the lack of the two physical processes creates problems. The slowly falling precipitation (snow) falls to the wrong surface grid box, which may have led to the observed spotty-precipitation pattern. To solve the problem two prognositic variables, snow and rain, are added. Addition of the two precipitation variable allows their advection. The corresponding sedimentation process are also added. In this study we examine the effect of precipitation advection and sedimentation on the precipitation pattern, associated precipitation skills and clouds.

The effect of particulate matter components on the acidity of rain in upper Silesia (Poland)

International Nuclear Information System (INIS)

Hlawiczka, Stanislaw; Korszun, Katarzyna

2012-01-01

Analysis of data characterizing the chemical composition of atmospheric precipitation was presented, with an emphasis on components responsible for neutralization of rain acidity. For this purpose, chemometric methods were applied. Based on a principal component analysis (PCA) a strong correlation between precipitation pH and potassium and ammonium ions in the heating period (October-March) and potassium and sodium ions in the non-heating period (April-September) was observed. Additionally, a classification of eight variables, i.e., Na + , K + , Mg 2+ , Ca 2+ , SO 4 2- , NO 3 - , Cl - , and NH 4 + according to their similarities was made using a cluster analysis. Based on this study, two ions, potassium and ammonium, together with the pH value were classified into one group (cluster) in the heating period while in the non-heating period ions of potassium and sodium were clustered together with the pH. The results of the cluster analysis indicated that the selected ions contributed the most to the neutralization of the atmospheric precipitation acidity. This relationship was confirmed by a discriminant analysis in which potassium and ammonium ions were selected as components of the highest potential for precipitation classification according to its acidity degree. The relationship between the precipitation pH and the number of non-precipitation days preceding the precipitation was also analyzed. It was found that although the observed an increase of the pH value was not very high, nevertheless, the effect of the duration of the period preceding the precipitation on the pH value recorded on the day of the precipitation occurrence was quite evident. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Relative importance of precipitation frequency and intensity in inter-annual variation of precipitation in Singapore during 1980-2013

Science.gov (United States)

Li, Xin; Babovic, Vladan

2017-04-01

Observed studies on inter-annual variation of precipitation provide insight into the response of precipitation to anthropogenic climate change and natural climate variability. Inter-annual variation of precipitation results from the concurrent variations of precipitation frequency and intensity, understanding of the relative importance of frequency and intensity in the variability of precipitation can help fathom its changing properties. Investigation of the long-term changes of precipitation schemes has been extensively carried out in many regions across the world, however, detailed studies of the relative importance of precipitation frequency and intensity in inter-annual variation of precipitation are still limited, especially in the tropics. Therefore, this study presents a comprehensive framework to investigate the inter-annual variation of precipitation and the dominance of precipitation frequency and intensity in a tropical urban city-state, Singapore, based on long-term (1980-2013) daily precipitation series from 22 rain gauges. First, an iterative Mann-Kendall trend test method is applied to detect long-term trends in precipitation total, frequency and intensity at both annual and seasonal time scales. Then, the relative importance of precipitation frequency and intensity in inducing the inter-annual variation of wet-day precipitation total is analyzed using a dominance analysis method based on linear regression. The results show statistically significant upward trends in wet-day precipitation total, frequency and intensity at annual time scale, however, these trends are not evident during the monsoon seasons. The inter-annual variation of wet-day precipitation is mainly dominated by precipitation intensity for most of the stations at annual time scale and during the Northeast monsoon season. However, during the Southwest monsoon season, the inter-annual variation of wet-day precipitation is mainly dominated by precipitation frequency. These results have

Inhibition of salt precipitation, corrosion and corrosion fatigue of steel in neutral environments

International Nuclear Information System (INIS)

Mikhajlovskij, V.Ya.; Slobodyan, Z.V.; Soprunyuk, N.G.; Ivanov, A.M.

1983-01-01

Processes of salt precipitation, corrosion under dynamic and static conditions, are studied as well as corrosion fatigue of 20 and 40Kh steels in neutral aqueous media without and with the addition of compounds of several classes. The solution of calcium bicarbonate with the initial concentration [Ca(HCO 3 ) 2 ]=1.3 g/l and 3% NaCl solution in distilled water are used for investigation. The effectiveness index of salt precipitation inhibitor is determined by the change in the rate of calcium bicarbonate transformation into carbonate. The combination of results obtained permits to make the conclusion that tripolyphosphate and pyrophosphoric acid are rather perspective inhibitors of complex effect with low protective concentrations

Precipitation of organic arsenic compounds and their degradation products during struvite formation

Energy Technology Data Exchange (ETDEWEB)

Lin, Jin-Biao; Yuan, Shoujun [School of Civil Engineering, Hefei University of Technology, Hefei 230009 (China); Institute of Water Treatment and Wastes Reutilization, Hefei University of Technology, Hefei 230009 (China); Wang, Wei, E-mail: dwhit@126.com [School of Civil Engineering, Hefei University of Technology, Hefei 230009 (China); Institute of Water Treatment and Wastes Reutilization, Hefei University of Technology, Hefei 230009 (China); Hu, Zhen-Hu, E-mail: zhhu@hfut.edu.cn [School of Civil Engineering, Hefei University of Technology, Hefei 230009 (China); Institute of Water Treatment and Wastes Reutilization, Hefei University of Technology, Hefei 230009 (China); Yu, Han-Qing [Department of Chemistry, University of Science & Technology of China, Hefei 230026 (China)

2016-11-05

Highlights: • Organic and inorganic arsenic compounds precipitated during struvite formation. • Precipitation of organic arsenic compounds in struvite decreased with increasing pH. • Arsenate easily precipitate in struvite as compared to organic arsenic compounds. • Arsenic compounds in solution affected the shape of struvite crystallization products. - Abstract: Roxarsone (ROX) and arsanilic acid (ASA) have been extensively used as organoarsenic animal feed additives. Organic arsenic compounds and their degradation products, arsenate (As(V)) and arsenite (As(III)), exist in the effluent from anaerobic reactors treating animal manure contaminated by ROX or ASA with ammonium (NH{sub 4}{sup +}-N) and phosphate (PO{sub 4}{sup 3−}-P) together. Therefore, arsenic species in the effluent might be involved in the struvite formation process. In this study, the involvement of organic arsenic compounds and their degradation products As(V) and As(III) in the struvite crystallization was investigated. The results demonstrated that arsenic compounds did not substantially affect the PO{sub 4}{sup 3−}-P recovery, but confirmed the precipitation of arsenic during struvite formation. The precipitation of arsenic compounds in struvite was considerably affected by a solution pH from 9.0 to 11.0. With an increase in pH, the content of ASA and ROX in the precipitation decreased, but the contents of As(III) and As(V) increased. In addition, the arsenic content of As(V) in the struvite was higher than that of As(III), ASA and ROX. The results indicated that the struvite could be contaminated when the solution contains arsenic species, but that could be minimized by controlling the solution pH and maintaining anaerobic conditions during struvite formation.

Mechanisms of Se(IV) Co-precipitation with Ferrihydrite at Acidic and Alkaline Conditions and Its Behavior during Aging

DEFF Research Database (Denmark)

Francisco, Paul Clarence M.; Sato, Tsutomu; Otake, Tsubasa

2018-01-01

in nanopore and defect structures. These results demonstrate a potential long-term immobilization pathway for Se(IV) even after phase transformation. This work presents one of the first direct insights on Se(IV) co-precipitation and its behavior in response to iron phase transformations.......Understanding the form of Se(IV) co-precipitated with ferrihydrite and its subsequent behavior during phase transformation is critical to predicting its long-term fate in a range of natural and engineered settings. In this work, Se(IV)-ferrihydrite co-precipitates formed at different pH were......, Se(IV) was removed dominantly as a ferric selenite-like phase intimately associated with ferrihydrite, while at pH 10, it was mostly present as a surface species on ferrihydrite. Similarly, the behavior of Se(IV) and the extent of its retention during phase transformation varied with pH. At pH 5, Se...

Acid rain publications by the U.S. Fish and Wildlife Service, 1979-1989

Science.gov (United States)

Villella, Rita F.

1989-01-01

Pollution of aquatic and terrestrial ecosystems has been a concern to society since the burning of fossil fuels began in the industrial revolution. In the past decade or so, this concern has been heightened by evidence that chemical transformation in the atmosphere of combustion by-products and subsequent long-range transport can cause environmental damage in remote areas. The extent of this damage and the rates of ecological recovery were largely unknown. "Acid rain" became the environmental issue of the 1980's. To address the increasing concerns of the public, in 1980 the Federal government initiated a 10-year interagency research program to develop information that could be used by the President and the Congress in making decisions for emission controls. The U.S. Fish and Wildlife Service has been an active participant in acid precipitation research. The Service provided support to a number of scientific conferences and forums, including the Action Seminar on Acid Precipitation held in Toronto, Canada, in 1979, an international symposium on Acidic Precipitation and Fishery Impacts in Northeastern North America in 1981, and a symposium on Acidic Precipitation and Atmospheric Deposition: A Western Perspective in 1982. These meetings as well as the growing involvement with the government's National Acidic Precipitation Assessment Program placed the Service in the lead in research on the biological effects of acidic deposition. Research projects have encompassed water chemistry, aquatic invertebrates, amphibians, fish, and waterfowl. Water quality surveys have been conducted to help determine the extent of acid precipitation effects in the northeast, Middle Atlantic, and Rocky Mountain regions. In addition to lake and stream studies, research in wetland and some terrestrial habitats has also been conducted. Specific projects have addressed important sport species such as brook trout (Salvelinus fontinalis), Atlantic salmon (Salmo salar), and striped bass (Morone

Uric acid nephrolithiasis: An update.

Science.gov (United States)

Cicerello, Elisa

2018-04-01

Uric acid nephrolithiasis appears to increase in prevalence. While a relationship between uric acid stones and low urinary pH has been for long known, additional association with various metabolic conditions and pathophysiological basis has recently been elucidated. Some conditions such as diabetes and metabolic syndrome disease, excessive dietary intake, and increased endogenous uric acid production and/or defect in ammoniagenesis are associated with low urinary pH. In addition, the phenomenon of global warming could result in an increase in areas with greater climate risk for uric acid stone formation. There are three therapeutic steps to be taken for management of uric acid stones: identification of urinary pH profiles, assessment of urinary volume status, and identification of disorders leading to excessive uric acid production. However, the most important factor for uric acid stone formation is acid urinary pH, which is a prerequisite for uric acid precipitation. This article reviews recent insights into the pathophysiology of uric acid stones and their management.

Major hydrogeochemical processes in an Acid Mine Drainage affected estuary

International Nuclear Information System (INIS)

Asta, Maria P.; Calleja, Maria Ll.; Pérez-López, Rafael; Auqué, Luis F.

2015-01-01

Highlights: • Mixing of acid riverine water with alkaline seawater was studied in an estuary. • Combination of data and geochemical tools allowed modeling the water mixing. • The main geochemical processes were identified and for the first time quantified. • Water chemistry is the result of mixing, dissolution-precipitation and sorption. • Main reactions: gypsum and calcite dissolution and Al and Fe solids precipitation. - Abstract: This study provides geochemical data with the aim of identifying and quantifying the main processes occurring in an Acid Mine Drainage (AMD) affected estuary. With that purpose, water samples of the Huelva estuary were collected during a tidal half-cycle and ion–ion plots and geochemical modeling were performed to obtain a general conceptual model. Modeling results indicated that the main processes responsible for the hydrochemical evolution of the waters are: (i) the mixing of acid fluvial water with alkaline ocean water; (ii) precipitation of Fe oxyhydroxysulfates (schwertmannite) and hydroxides (ferrihydrite); (iii) precipitation of Al hydroxysulfates (jurbanite) and hydroxides (amorphous Al(OH) 3 ); (iv) dissolution of calcite; and (v) dissolution of gypsum. All these processes, thermodynamically feasible in the light of their calculated saturation states, were quantified by mass-balance calculations and validated by reaction-path calculations. In addition, sorption processes were deduced by the non-conservative behavior of some elements (e.g., Cu and Zn)

Centrifugal precipitation chromatography

Science.gov (United States)

Ito, Yoichiro; Lin, Qi

2009-01-01

Centrifugal precipitation chromatography separates analytes according their solubility in ammonium sulfate (AS) solution and other precipitants. The separation column is made from a pair of long spiral channels partitioned with a semipermeable membrane. In a typical separation, concentrated ammonium sulfate is eluted through one channel while water is eluted through the other channel in the opposite direction. The countercurrent process forms an exponential AS concentration gradient through the water channel. Consequently, protein samples injected into the water channel is subjected to a steadily increasing AS concentration and at the critical AS concentration they are precipitated and deposited in the channel bed by the centrifugal force. Then the chromatographic separation is started by gradually reducing the AS concentration in the AS channel which lowers the AS gradient concentration in the water channel. This results in dissolution of deposited proteins which are again precipitated at an advanced critical point as they move through the channel. Consequently, proteins repeat precipitation and dissolution through a long channel and finally eluted out from the column in the order of their solubility in the AS solution. The present method has been successfully applied to a number of analytes including human serum proteins, recombinant ketosteroid isomerase, carotenoid cleavage enzymes, plasmid DNA, polysaccharide, polymerized pigments, PEG-protein conjugates, etc. The method is capable to single out the target species of proteins by affinity ligand or immunoaffinity separation. PMID:19541553

Carbonate precipitation under bulk acidic conditions as a potential biosignature for searching life on Mars

NARCIS (Netherlands)

Fernández-Remolar, David C.; Preston, Louisa J.; Sánchez-Román, Mónica; Izawa, Matthew R.M.; Huang, L.; Southam, Gordon; Banerjee, Neil R.; Osinski, Gordon R.; Flemming, Roberta; Gómez-Ortíz, David; Prieto-Ballesteros, Olga; Rodríguez, Nuria; Amils, Ricardo; Darby Dyar, M.

2012-01-01

Recent observations of carbonate minerals in ancient Martian rocks have been interpreted as evidence for the former presence of circumneutral solutions optimal for carbonate precipitation. Sampling from surface and subsurface regions of the low-pH system of Río Tinto has shown, unexpectedly, that

Synthesis and characterization of magnetite nanoparticles via the chemical co-precipitation method

International Nuclear Information System (INIS)

Petcharoen, K.; Sirivat, A.

2012-01-01

Highlights: ► Size-controlled magnetite nanoparticles were prepared via the chemical co-precipitation method in the range of 10–40 nm. ► The electrical conductivity of the smallest particle size is 1.3 × 10 −3 S/cm which belongs to the semiconductor material group. ► The surface modification of magnetite nanoparticles can provide the suspension stability over 1 week. - Abstract: Magnetite nanoparticles were synthesized via the chemical co-precipitation method using ammonium hydroxide as the precipitating agent. The size of the magnetite nanoparticles was carefully controlled by varying the reaction temperature and through the surface modification. Herein, the hexanoic acid and oleic acid were introduced as the coating agents during the initial crystallization phase of the magnetite. Their structure and morphology were characterized by the Fourier transform infrared spectroscopy (FTIR), the X-ray diffraction (XRD) and the field-emission scanning electron microscopy (FE-SEM). Moreover, the electrical and magnetic properties were studied by using a conductivity meter and a vibrating sample magnetometer (VSM), respectively. Both of the bare magnetite and the coated magnetite were of the cubic spinel structure and the spherical-shaped morphology. The reaction temperature and the surface modification critically affected the particle size, the electrical conductivity, and the magnetic properties of these particles. The particle size of the magnetite was increased through the surface modification and reaction temperature. In this study, the particle size of the magnetite nanoparticles was successfully controlled to be in the range of 10–40 nm, suitable for various biomedical applications. The electrical conductivity of the smallest particle size was 1.3 × 10 −3 S/cm, within the semi-conductive materials range, which was higher than that of the largest particle by about 5 times. All of the magnetite nanoparticles showed the superparamagnetic behavior with

Near-Infrared Spectroscopy as an Analytical Process Technology for the On-Line Quantification of Water Precipitation Processes during Danhong Injection.

Science.gov (United States)

Liu, Xuesong; Wu, Chunyan; Geng, Shu; Jin, Ye; Luan, Lianjun; Chen, Yong; Wu, Yongjiang

2015-01-01

This paper used near-infrared (NIR) spectroscopy for the on-line quantitative monitoring of water precipitation during Danhong injection. For these NIR measurements, two fiber optic probes designed to transmit NIR radiation through a 2 mm flow cell were used to collect spectra in real-time. Partial least squares regression (PLSR) was developed as the preferred chemometrics quantitative analysis of the critical intermediate qualities: the danshensu (DSS, (R)-3, 4-dihydroxyphenyllactic acid), protocatechuic aldehyde (PA), rosmarinic acid (RA), and salvianolic acid B (SAB) concentrations. Optimized PLSR models were successfully built and used for on-line detecting of the concentrations of DSS, PA, RA, and SAB of water precipitation during Danhong injection. Besides, the information of DSS, PA, RA, and SAB concentrations would be instantly fed back to site technical personnel for control and adjustment timely. The verification experiments determined that the predicted values agreed with the actual homologic value.

Remediation of Acid Mine Drainage with Sulfate Reducing Bacteria

Science.gov (United States)

Hauri, James F.; Schaider, Laurel A.

2009-01-01

Sulfate reducing bacteria have been shown to be effective at treating acid mine drainage through sulfide production and subsequent precipitation of metal sulfides. In this laboratory experiment for undergraduate environmental chemistry courses, students design and implement a set of bioreactors to remediate acid mine drainage and explain observed…

Cesium Salts of Phosphotungstic Acid: Comparison of Surface ...

African Journals Online (AJOL)

NICO

acidity and lowest solubility in reaction media in comparison with the other cesium content salts. KEYWORDS. Polyoxometalates, cesium ... insoluble salt of HPA is cesium salt of tungstophosphoric acid,. CsxH3-xPW12O40 (CsxPW), a ... of Cs2CO3, very fine particles (precipitates) were formed to make the solution milky.

The Version 2 Global Precipitation Climatology Project (GPCP) Monthly Precipitation Analysis (1979-Present)

Science.gov (United States)

Adler, Robert F.; Huffman, George J.; Chang, Alfred; Ferraro, Ralph; Xie, Ping-Ping; Janowiak, John; Rudolf, Bruno; Schneider, Udo; Curtis, Scott; Bolvin, David

2003-01-01

The Global Precipitation Climatology Project (GPCP) Version 2 Monthly Precipitation Analysis is described. This globally complete, monthly analysis of surface precipitation at 2.5 degrees x 2.5 degrees latitude-longitude resolution is available from January 1979 to the present. It is a merged analysis that incorporates precipitation estimates from low-orbit-satellite microwave data, geosynchronous-orbit-satellite infrared data, and rain gauge observations. The merging approach utilizes the higher accuracy of the low-orbit microwave observations to calibrate, or adjust, the more frequent geosynchronous infrared observations. The data set is extended back into the premicrowave era (before 1987) by using infrared-only observations calibrated to the microwave-based analysis of the later years. The combined satellite-based product is adjusted by the raingauge analysis. This monthly analysis is the foundation for the GPCP suite of products including those at finer temporal resolution, satellite estimate, and error estimates for each field. The 23-year GPCP climatology is characterized, along with time and space variations of precipitation.

Human plasma-derived immunoglobulin G fractionated by an aqueous two-phase system, caprylic acid precipitation, and membrane chromatography has a high purity level and is free of detectable in vitro thrombogenic activity.

Science.gov (United States)

Vargas, M; Segura, Á; Wu, Y-W; Herrera, M; Chou, M-L; Villalta, M; León, G; Burnouf, T

2015-02-01

Instituto Clodomiro Picado has developed an immunoglobulin G (IgG) plasma fractionation process combining a polyethylene glycol/phosphate aqueous two-phase system (ATPS), caprylic acid precipitation and anion-exchange membrane chromatography. We evaluated the purity and in vitro thrombogenicity of such IgG, in line with current international requirements. Contributions of the different production steps to reduce thrombogenicity were assessed at 0·2 l-scale, and then the methodology was scaled-up to a 10 l-scale and final products (n = 3) were analysed. Purity, immunoglobulin composition, and subclass distribution were determined by electrophoretic and immunochemical methods. The in vitro thrombogenic potential was determined by a thrombin generation assay (TGA) using a Technothrombin fluorogenic substrate. Prekallikrein activator (PKA), plasmin, factor Xa, thrombin and thrombin-like activities were assessed using S-2302, S-2251, S-2222, S-2238 and S-2288 chromogenic substrates, respectively, and FXI by an ELISA. The thrombogenicity markers were reduced mostly during the ATPS step and were found to segregate mostly into the discarded liquid upper phase. The caprylic acid precipitation eliminated the residual procoagulant activity. The IgG preparations made from the 10 l-batches contained 100% gamma proteins, low residual IgA and undetectable IgM. The IgG subclass distribution was not substantially affected by the process. TGA and amidolytic activities revealed an undetectable in vitro thrombogenic risk and the absence of proteolytic enzymes in the final product. Fractionating human plasma by an ATPS combined with caprylic acid and membrane chromatography resulted in an IgG preparation of high purity and free of a detectable in vitro thrombogenic risk. © 2014 International Society of Blood Transfusion.

Satellite-Based Precipitation Datasets

Science.gov (United States)

Munchak, S. J.; Huffman, G. J.

2017-12-01

Of the possible sources of precipitation data, those based on satellites provide the greatest spatial coverage. There is a wide selection of datasets, algorithms, and versions from which to choose, which can be confusing to non-specialists wishing to use the data. The International Precipitation Working Group (IPWG) maintains tables of the major publicly available, long-term, quasi-global precipitation data sets (http://www.isac.cnr.it/ ipwg/data/datasets.html), and this talk briefly reviews the various categories. As examples, NASA provides two sets of quasi-global precipitation data sets: the older Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) and current Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (GPM) mission (IMERG). Both provide near-real-time and post-real-time products that are uniformly gridded in space and time. The TMPA products are 3-hourly 0.25°x0.25° on the latitude band 50°N-S for about 16 years, while the IMERG products are half-hourly 0.1°x0.1° on 60°N-S for over 3 years (with plans to go to 16+ years in Spring 2018). In addition to the precipitation estimates, each data set provides fields of other variables, such as the satellite sensor providing estimates and estimated random error. The discussion concludes with advice about determining suitability for use, the necessity of being clear about product names and versions, and the need for continued support for satellite- and surface-based observation.

Precipitation of iron (III) using magnesium oxide in fluidized bed; Precipitacion de hierro (III) utilizando oxido de magnesio en lecho fluidizado

Energy Technology Data Exchange (ETDEWEB)

Esteban-Bocardo, P. A.; Ferreira-Rocha, S. D.

2006-07-01

A process for iron (III) removal by hydroxide precipitation from and acid synthetic inorganic effluent using magnesium oxide as an alternative precipitant agent in a fluidized bed was developed. An acid synthetic inorganic effluent containing 100 and 200 mg/l of ferric ions (pH=1.0) was continuously fed up to the acrylic column (30 cm high and 2 cm diameter) during 180 minutes. Magnesium oxide pulp (3% v/v) was injected at the beginning of the experiment in order to allow the iron hydroxides precipitation. The concentration and pH profiles agreed in their curves, while the pH profile rose,the concentration profile decreased and a high percentage of iron removal (higher to 99%) was reached. Extremely low iron concentrations have been reached, thus permitting to attend to the environmental standard of 10.0 mg/l for discharge of effluent containing ferric ions established by the law DN 10/86 of COPAM (Conselho de Politica Ambiental do Estado de Minas Gerais-Brazil). (Author)

A non-classical view of the modulation of mineral precipitation by organic additives

Science.gov (United States)

Ruiz-Agudo, Encarnacion; Ruiz-Agudo, Cristina; Burgos-Cara, Alejandro; Putnis, Christine; Rodriguez-Navarro, Carlos; Putnis, Andrew

2016-04-01

Questions persist on the mechanisms of crystallization of sparingly soluble minerals such as calcium carbonate, calcium oxalate or barium sulphate. Compared to CaCO3, the mechanisms of nucleation and growth in the CaC2O4-H2O or BaSO4-H2O systems have received less attention. These phases are important due to their relevance as biominerals and/or unwanted mineral deposits in technological applications. Growing evidence suggests that sparingly soluble salts form by non-classical nucleation and growth pathways, where pre-nucleation ion associates and amorphous (solid or liquid) precursor phase(s) play a critical role (e.g. Rodríguez-Navarro et al. (2015), Ruiz-Agudo et al. (2015)). Indeed the identification of pre-nucleation species in these systems and their strong interactions with organic compounds (Verch et al. 2011) raises the possibility that the control of organics on biomineralization may begin even earlier than previously thought. A sound knowledge of the physical mechanisms by which acidic macromolecules affect nucleation and early growth may offer general insights concerning the molecular control of biomineralization, as well as being critical for improving strategies to control unwanted mineral deposition or for the synthesis of biomimetic materials. Here we present investigations on the initial stages of the precipitation of these relevant minerals in organic-free solutions to identify the precipitation pathway and to look for any potential precursor phase(s) to the final, crystalline polymorph. As well, we explore the effects that several acidic organic compounds have on the different precipitation stages identified. We find that organic additives such as citric acid, polyacrilic acid or a commercial copolymer of maleic acid/allyl sulfonic acid with phosphonate groups can be active at modifying pre-nucleation stages (destabilizing of pre-nucleation species or hampering the aggregation and growth of pre-nucleation associates) and subsequently strongly

Two-stage precipitation of neptunium (IV) oxalate

International Nuclear Information System (INIS)

Luerkens, D.W.

1983-07-01

Neptunium (IV) oxalate was precipitated using a two-stage precipitation system. A series of precipitation experiments was used to identify the significant process variables affecting precipitate characteristics. Process variables tested were input concentrations, solubility conditions in the first stage precipitator, precipitation temperatures, and residence time in the first stage precipitator. A procedure has been demonstrated that produces neptunium (IV) oxalate particles that filter well and readily calcine to the oxide

The effect of particulate matter components on the acidity of rain in upper Silesia (Poland)

Energy Technology Data Exchange (ETDEWEB)

Hlawiczka, Stanislaw [Institute for Ecology of Industrial Areas, Katowice (Poland); Department of Environmental Protection and Engineering, Technical University of Czestochowa, Czestochowa (Poland); Korszun, Katarzyna [Institute for Ecology of Industrial Areas, Katowice (Poland)

2012-07-15

Analysis of data characterizing the chemical composition of atmospheric precipitation was presented, with an emphasis on components responsible for neutralization of rain acidity. For this purpose, chemometric methods were applied. Based on a principal component analysis (PCA) a strong correlation between precipitation pH and potassium and ammonium ions in the heating period (October-March) and potassium and sodium ions in the non-heating period (April-September) was observed. Additionally, a classification of eight variables, i.e., Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, SO{sub 4}{sup 2-}, NO{sub 3}{sup -}, Cl{sup -}, and NH{sub 4}{sup +} according to their similarities was made using a cluster analysis. Based on this study, two ions, potassium and ammonium, together with the pH value were classified into one group (cluster) in the heating period while in the non-heating period ions of potassium and sodium were clustered together with the pH. The results of the cluster analysis indicated that the selected ions contributed the most to the neutralization of the atmospheric precipitation acidity. This relationship was confirmed by a discriminant analysis in which potassium and ammonium ions were selected as components of the highest potential for precipitation classification according to its acidity degree. The relationship between the precipitation pH and the number of non-precipitation days preceding the precipitation was also analyzed. It was found that although the observed an increase of the pH value was not very high, nevertheless, the effect of the duration of the period preceding the precipitation on the pH value recorded on the day of the precipitation occurrence was quite evident. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

The dilemma of an acidic sky

International Nuclear Information System (INIS)

Jenkins, T.

1984-01-01

A discussion of studies detailing the damaging effects of acid precipitation in North America and Europe is followed by a commentary on the controversial political and economic issues associated with forestalling deterioration of the environment. A comprehensive bibliography is included

Modeling winter precipitation over the Juneau Icefield, Alaska, using a linear model of orographic precipitation

Science.gov (United States)

Roth, Aurora; Hock, Regine; Schuler, Thomas V.; Bieniek, Peter A.; Pelto, Mauri; Aschwanden, Andy

2018-03-01

Assessing and modeling precipitation in mountainous areas remains a major challenge in glacier mass balance modeling. Observations are typically scarce and reanalysis data and similar climate products are too coarse to accurately capture orographic effects. Here we use the linear theory of orographic precipitation model (LT model) to downscale winter precipitation from a regional climate model over the Juneau Icefield, one of the largest ice masses in North America (>4000 km2), for the period 1979-2013. The LT model is physically-based yet computationally efficient, combining airflow dynamics and simple cloud microphysics. The resulting 1 km resolution precipitation fields show substantially reduced precipitation on the northeastern portion of the icefield compared to the southwestern side, a pattern that is not well captured in the coarse resolution (20 km) WRF data. Net snow accumulation derived from the LT model precipitation agrees well with point observations across the icefield. To investigate the robustness of the LT model results, we perform a series of sensitivity experiments varying hydrometeor fall speeds, the horizontal resolution of the underlying grid, and the source of the meteorological forcing data. The resulting normalized spatial precipitation pattern is similar for all sensitivity experiments, but local precipitation amounts vary strongly, with greatest sensitivity to variations in snow fall speed. Results indicate that the LT model has great potential to provide improved spatial patterns of winter precipitation for glacier mass balance modeling purposes in complex terrain, but ground observations are necessary to constrain model parameters to match total amounts.

Modelled Precipitation Over Greenland

Data.gov (United States)

National Aeronautics and Space Administration — This data set includes the annual total precipitation from 1985 to 1999 and monthly total precipitation from January 1985 to December 1999. The data is derived from...

Electrical operation of electrostatic precipitators

CERN Document Server

Parker, Ken

2003-01-01

The electrostatic precipitator remains on of the most cost effective means of controlling the emission of particulates from most industrial processes. This book will be of interest to both users and suppliers of electrostatic precipitators as well as advanced students on environmental based courses. The author identifies the physical and engineering basis for the development of electrical equipment for electrostatic precipitators and thoroughly explores the technological factors which optimize the efficiency of the precipitator and hence minimize emissions, as well as future developments in th

Calcium extraction from brine water and seawater using oxalic acid

Science.gov (United States)

Natasha, Nadia Chrisayu; Lalasari, Latifa Hanum

2017-01-01

Calcium can be extracted not only from rocks but also from natural liquor such as seawater and brine water. In order to extract the calcium from seawater and brine water, oxalic acid was used in this research. Effect of variations of the volume of the oxalic acid at a constant concentration in seawater and brine water to produce calcium was investigated. The concentration of oxalic acid was 100 g/l and the variations of its volume were 2 ml, 4 ml, 6 ml, 8 ml, 10 ml, 20 ml, 30 ml, 40 ml, and 50 ml. The used seawater and brine water were firstly evaporated from 100 ml into 50 ml and then the oxalic acid was added into them with mixing to produce the calcium precipitates. The precipitates were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM) and the filtrates were analyzed by inductively coupled plasma-optical emission spectrometry (ICP-OES). The SEM analysis showed that the precipitates from brine water were consisted of only calcium compound while from seawater sodium one was also found along with calcium compound. The XRD analysis showed that the calcium was present in the form of calcium oxalate for both seawater and brine water. The ICP-OES analysis of the filtrate from seawater precipitation showed that the its calcium content was decreased from 826.20 ppm to 0.04 ppm while from brine water, it decreased from 170.06 ppm to 1.96 ppm. These results showed that both seawater and brine water have the potential to be a raw material for calcium production.

Waste acid detoxification and reclamation: Summary of bench-scale tests for FY 1986 and FY 1987

Energy Technology Data Exchange (ETDEWEB)

Stewart, T.L.

1987-09-01

Processes to reduce the volume, quantity, and toxicity of metal-bearing waste acid are being demonstrated at Pacific Northwest Laboratory. Two precipitation processes and a distillation process are being developed to minimize waste from fuel fabrication operations, which comprise a series of metal-finishing operations. Waste process acids such as HF-HNO/sub 3/, etch solutions containing Zr as a major metal impurity, and HNO/sub 3/ strip solution containing Cu as a major metal impurity are detoxified and reclaimed by concurrently precipitating heavy metals and regenerating acid for recycle. Acid from a third waste acid stream generated from chemical milling operations will be reclaimed using distillation. This stream comprises HNO/sub 3/ and H/sub 2/SO/sub 4/ containing U as the major metal impurity. Distillation allows NO/sub 3//sup -/ to be displaced by SO/sub 4//sup -2/ in metal salts; free HNO/sub 3/ is then vaporized from the U-bearing sulfate stream. Uranium can be recovered from the sulfate stream in a downstream precipitation step. 10 refs., 15 figs., 13 tabs.

Separation of Am-Cm from Al(NO3)3 waste solutions by in-canyon-tank precipitation as oxalates

International Nuclear Information System (INIS)

Gray, L.W.; Burney, G.A.; Wilson, T.W.; McKibben, J.M.; Bibler, N.E.; Holtzscheiter, E.W.; Campbell, T.G.

1982-04-01

A process for recovery of Am-Cm residues from high-activity waste concentrates has been developed specifically for application in Savannah River Plant (SRP) canyon tanks. The Am-Cm residues were collected from a campaign to produce plutonium containing high isotopic concentrations of 242 Pu. The separation of Am-Cm from the high-activity waste stream, containing about 2M Al(NO 3 ) 3 , is necessary to produce an acceptable feed solution for a later pressurized cation exchange chromatography separation and purification step. The new process includes formic acid denitration, adjustment of contaminating cations by evaporation and water dilution, and oxalate precipitation of the actinides and lanthanides. After washing, the precipitate was dissolved in 8M nitric acid and the oxalate was destroyed by nitric acid oxidation that was catalyzed by manganous ions. This new process generates about one-fourth the waste of the californium solvent extraction process, which it replaced. The new process also produces a cleaner feed solution for the pressurized cation exchange chromatography separation and purification step

Precipitates in irradiated Zircaloy

International Nuclear Information System (INIS)

Chung, H.M.

1985-10-01

Precipitates in high-burnup (>20 MWd/kg U) Zircaloy spent-fuel cladding discharged from commercial boiling- and pressurized-water reactors have been characterized by TEM-HVEM. Three classes of primary precipitates were observed in the irradiated Zircaloys: Zr 3 O (2 to 6 nm), cubic-ZrO 2 (greater than or equal to 10 nm), and delta-hydride (35 to 100 nm). The former two precipitations appears to be irradiation induced in nature. Zr(Fe/sub x/Cr/sub 1-x/) 2 and Zr 2 (Fe/sub x/Ni/sub 1-x/) intermetallics, which are the primary precipitates in unirradiated Zircaloys, were largely dissolved after the high burnup. It seems, therefore, that the influence of the size and distribution of the intermetallics on the corrosion behavior may be quite different for the irradiated Zircaloys

Heavy metal immobilization via microbially induced carbonate precipitation and co-precipitation

Science.gov (United States)

Lauchnor, E. G.; Stoick, E.

2017-12-01

Microbially induced CaCO3 precipitation (MICP) has been successfully used in applications such as porous media consolidation and sealing of leakage pathways in the subsurface, and it has the potential to be used for remediation of metal and radionuclide contaminants in surface and groundwater. In this work, MICP is investigated for removal of dissolved heavy metals from contaminated mine discharge water via co-precipitation in CaCO3 or formation of other metal carbonates. The bacterially catalyzed hydrolysis of urea produces inorganic carbon and ammonium and increases pH and the saturation index of carbonate minerals to promote precipitation of CaCO3. Other heavy metal cations can be co-precipitated in CaCO3 as impurities or by replacing Ca2+ in the crystal lattice. We performed laboratory batch experiments of MICP in alkaline mine drainage sampled from an abandoned mine site in Montana and containing a mixture of heavy metals at near neutral pH. Both a model bacterium, Sporosarcina pasteurii, and a ureolytic bacterium isolated from sediments on the mine site were used to promote MICP. Removal of dissolved metals from the aqueous phase was determined via inductively coupled plasma mass spectrometry and resulting precipitates were analyzed via electron microscopy and energy dispersive x-ray spectroscopy (EDX). Both S. pasteurii and the native ureolytic isolate demonstrated ureolysis, increased the pH and promoted precipitation of CaCO3 in batch tests. MICP by the native bacterium reduced concentrations of the heavy metals zinc, copper, cadmium, nickel and manganese in the water. S. pasteurii was also able to promote MICP, but with less removal of dissolved metals. Analysis of precipitates revealed calcium carbonate and phosphate minerals were likely present. The native isolate is undergoing identification via 16S DNA sequencing. Ongoing work will evaluate biofilm formation and MICP by the isolate in continuous flow, gravel-filled laboratory columns. This research

Acid Rain

Science.gov (United States)

Bricker, Owen P.; Rice, Karen C.

1995-01-01

Although acid rain is fading as a political issue in the United States and funds for research in this area have largely disappeared, the acidity of rain in the Eastern United States has not changed significantly over the last decade, and it continues to be a serious environmental problem. Acid deposition (commonly called acid rain) is a term applied to all forms of atmospheric deposition of acidic substances - rain, snow, fog, acidic dry particulates, aerosols, and acid-forming gases. Water in the atmosphere reacts with certain atmospheric gases to become acidic. For example, water reacts with carbon dioxide in the atmosphere to produce a solution with a pH of about 5.6. Gases that produce acids in the presence of water in the atmosphere include carbon dioxide (which converts to carbonic acid), oxides of sulfur and nitrogen (which convert to sulfuric and nitric acids}, and hydrogen chloride (which converts to hydrochloric acid). These acid-producing gases are released to the atmosphere through natural processes, such as volcanic emissions, lightning, forest fires, and decay of organic matter. Accordingly, precipitation is slightly acidic, with a pH of 5.0 to 5.7 even in undeveloped areas. In industrialized areas, most of the acid-producing gases are released to the atmosphere from burning fossil fuels. Major emitters of acid-producing gases include power plants, industrial operations, and motor vehicles. Acid-producing gases can be transported through the atmosphere for hundreds of miles before being converted to acids and deposited as acid rain. Because acids tend to build up in the atmosphere between storms, the most acidic rain falls at the beginning of a storm, and as the rain continues, the acids "wash out" of the atmosphere.

Precipitation and Hardening in Magnesium Alloys

Science.gov (United States)

Nie, Jian-Feng

2012-11-01

Magnesium alloys have received an increasing interest in the past 12 years for potential applications in the automotive, aircraft, aerospace, and electronic industries. Many of these alloys are strong because of solid-state precipitates that are produced by an age-hardening process. Although some strength improvements of existing magnesium alloys have been made and some novel alloys with improved strength have been developed, the strength level that has been achieved so far is still substantially lower than that obtained in counterpart aluminum alloys. Further improvements in the alloy strength require a better understanding of the structure, morphology, orientation of precipitates, effects of precipitate morphology, and orientation on the strengthening and microstructural factors that are important in controlling the nucleation and growth of these precipitates. In this review, precipitation in most precipitation-hardenable magnesium alloys is reviewed, and its relationship with strengthening is examined. It is demonstrated that the precipitation phenomena in these alloys, especially in the very early stage of the precipitation process, are still far from being well understood, and many fundamental issues remain unsolved even after some extensive and concerted efforts made in the past 12 years. The challenges associated with precipitation hardening and age hardening are identified and discussed, and guidelines are outlined for the rational design and development of higher strength, and ultimately ultrahigh strength, magnesium alloys via precipitation hardening.

An Effective Acid Combination for Enhanced Properties and Corrosion Control of Acidizing Sandstone Formation

International Nuclear Information System (INIS)

Shafiq, Mian Umer; Mahmud, Hisham Khaled Ben

2016-01-01

To fulfill the demand of the world energy, more technologies to enhance the recovery of oil production are being developed. Sandstone acidizing has been introduced and it acts as one of the important means to increase oil and gas production. Sandstone acidizing operation generally uses acids, which create or enlarge the flow channels of formation around the wellbore. In sandstone matrix acidizing, acids are injected into the formation at a pressure below the formation fracturing pressure, in which the injected acids react with mineral particles that may restrict the flow of hydrocarbons. Most common combination is Hydrofluoric Acid - Hydrochloric with concentration (3% HF - 12% HCl) known as mud acid. But there are some problems associated with the use of mud acid i.e., corrosion, precipitation. In this paper several new combinations of acids were experimentally screened to identify the most effective combination. The combinations used consist of fluoboric, phosphoric, formic and hydrofluoric acids. Cores were allowed to react with these combinations and results are compared with the mud acid. The parameters, which are analyzed, are Improved Permeability Ratio, strength and mineralogy. The analysis showed that the new acid combination has the potential to be used in sandstone acidizing. (paper)

Procedure for recovery from an uranium containing concentrate and phosphoric acid, as well as an uranium containing concentrate and phosphoric acid obtained by this procedure

International Nuclear Information System (INIS)

1980-01-01

The phosphate ore is dissolved in sulphuric acid and the formed calcium sulphate is separated from the solution. The uranium is then precipitated by adding ammonium fluoride solution to the remaining phosphoric acid solution. When the phosphate ore is dissolved in sulphuric acid, fluorine gas is liberated and this is then used to produce the ammonium fluoride solution. (Th.P.)

Spectrophotometric study of the complexes of cerium and uranides with diethylenetetraaminepentaacetic acid (DTPA); Contribution a l'etude de la complexation du cerium et des uranides par l'acide diethylenetetraminepentaacetique (DTPA)

Energy Technology Data Exchange (ETDEWEB)

Hafez, M B [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1968-03-01

A spectrophotometric determination was made of the complexes of cerium and uranides in their different degrees of oxidation with diethylenetriaminepentaacetic acid (DTPA). Two physico-chemical states, the ionic and hydrolysis ones, were considered. In the former case, we studied the influence of the pH on the formation of the complex, and whenever the complexes were stable, we determined the molecular ratio and calculated their stability constants. In the latter case, we studied the conditions of solubilization of the precipitate by formation of complexes soluble in water as a function of pH, age of the precipitate and time of precipitate-chelate contact. (authors) [French] Etude spectrophotometrique de la complexation du cerium et des uranides (uranium, neptunium, plutonium et americium) dans leurs differents etats d'oxydation par l'acide diethylenetriaminepentaacetique (DTPA). Deux etats physicochimiques ont retenu notre attention, l'etat ionique et l'etat precipite d'hydrolyse. Dans le premier cas, nous avons etudie l'influence du pH sur la formation du complexe, et dans tous les cas ou le complexe est stable, nous avons determine le rapport moleculaire (5) [element]/[chelatant] du complexe forme et nous avons calcule leurs constantes de stabilite. Dans le deuxieme cas, l'etat de precipite d'hydrolyse, nous avons etudie les conditions de solubilisation du precipite, par formation du complexe, en fonction du pH, de l'age du precipite et du temps de contact precipite - chelatant. (auteurs)

The magnetic and colloidal properties of CoFe2O4 nanoparticles synthesized by co-precipitation.

Science.gov (United States)

Gyergyek, Sašo; Drofenik, Miha; Makovec, Darko

2014-01-01

Magnetic CoFe(2)O(4) nanoparticles were synthesized by co-precipitation at 80 °C. This co-precipitation was achieved by the rapid addition of a strong base to an aqueous solution of cations. The investigation of the samples that were quenched at different times after the addition of the base, using transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDXS) and X-ray powder diffractometry, revealed the formation of a Co-deficient amorphous phase and Co(OH)(2), which rapidly reacted to form small CoFe(2)O(4) nanoparticles. The nanoparticles grew with the time of aging at elevated temperature. The colloidal suspensions of the nanoparticles were prepared in both an aqueous medium and in a non-polar organic medium, with the adsorption of citric acid and ricinoleic acid on the nanoparticles, respectively. The measurements of the room-temperature magnetization revealed the ferrimagnetic state of the CoFe(2)O(4) nanoparticles, while their suspensions displayed superparamagnetic behaviour.

Separation of fission 99Mo by alpha-benzoin oxime precipitation in nitric medium

International Nuclear Information System (INIS)

Yamaura, Mitiko; Freitas, Antonio A.; Egute, Nayara dos S.; Camilo, Ruth L.; Araujo, Izilda C.; Forbicini, Christina A.L.G. de O.

2011-01-01

Since 2009, the production of generators 99 Mo/ 99 mTc suffers a crisis of global supply due to technical problems of the two reactors which account for 64% of world production of fission 99 Mo. By the project of Brazilian Multipurpose Reactor (RMB), the Brazilian government invests in the construction of the first multipurpose reactor suitable for the domestic production of 99 Mo from LEU targets in order to supply of fission 99 Mo in the coming decades. The IPEN started the research of the technology and production of fission 99 Mo from acid and alkaline dissolutions of Low Enriched Uranium (LEU) targets as well as other used radioisotopes in nuclear medicine. This work is part of the research of the technology of the fission 99 Mo from acid dissolution of the LEU targets that is being developed at the IPEN. In this study the separation of the Mo by precipitation with alpha-benzoin oxime in nitric medium and the recovery by dissolution were investigated. The precipitation studies were performed by batch assays with nitric solution of Mo(VI), containing 99 Mo tracer, and uranyl ions. Influence of concentration of permanganate from 0.03 to 2.5%, dissolution temperature at 30 deg C and 150 deg C and the uranium concentration from 74 g.L -1 to 115 g.L -1 was studied. Results indicated that the precipitation of Mo with alpha-benzoin oxime from nitric medium is highly efficient, and its recovery by dissolution with basic solution of H 2 O 2 gave a high yield. (author)

Crystallization Kinetics of Precipitating Calcium from Yellow Phosphorus Slag Lixivium

Directory of Open Access Journals (Sweden)

Li, G. -B.

2014-11-01

Full Text Available The crystallization dynamic parameters of calcium sulphate were determined in the course of the precipitation conversion process of calcium in lixivium. The crystallization dynamic equations of calcium sulphate were achieved by multiple linear regression. The study results indicate that CaSO4 · 2 H2O crystal nucleation-growth kinetics equation in nitric acid leaching liquid of yellow phosphorus slag at room temperature is expressed by B0 = 2.904 · 1011 · G0.83 · MT 0.167.

Near-Infrared Spectroscopy as an Analytical Process Technology for the On-Line Quantification of Water Precipitation Processes during Danhong Injection

Directory of Open Access Journals (Sweden)

Xuesong Liu

2015-01-01

Full Text Available This paper used near-infrared (NIR spectroscopy for the on-line quantitative monitoring of water precipitation during Danhong injection. For these NIR measurements, two fiber optic probes designed to transmit NIR radiation through a 2 mm flow cell were used to collect spectra in real-time. Partial least squares regression (PLSR was developed as the preferred chemometrics quantitative analysis of the critical intermediate qualities: the danshensu (DSS, (R-3, 4-dihydroxyphenyllactic acid, protocatechuic aldehyde (PA, rosmarinic acid (RA, and salvianolic acid B (SAB concentrations. Optimized PLSR models were successfully built and used for on-line detecting of the concentrations of DSS, PA, RA, and SAB of water precipitation during Danhong injection. Besides, the information of DSS, PA, RA, and SAB concentrations would be instantly fed back to site technical personnel for control and adjustment timely. The verification experiments determined that the predicted values agreed with the actual homologic value.

Amino acid analysis in biological fluids by GC-MS

OpenAIRE

Kaspar, Hannelore

2009-01-01

Amino acids are intermediates in cellular metabolism and their quantitative analysis plays an important role in disease diagnostics. A gas chromatography-mass spectrometry (GC-MS) based method was developed for the quantitative analysis of free amino acids as their propyl chloroformate derivatives in biological fluids. Derivatization with propyl chloroformate could be carried out directly in the biological samples without prior protein precipitation or solid-phase extraction of the amino acid...

Development of precipitator of fluid film type

International Nuclear Information System (INIS)

Liu Yupu

1987-01-01

The precipitator of fluid film type is developed for the determination of fuel element cladding failure of water-cooled reactor. It integrates the scrubber, precipitator and detector. The jet of element cooling water automatically circulates carrier gas and the flow water film transfers precipitates onto the surface of centre electrode. Three different types are designed. On the special test loop, the uranium sample pellets of simulating cladding failure is measured. The sensitivity of precipitators, saturated precipitation voltage, incremental speed of signal, speed of driving out precipitates and the contents of the precipitates are determined. The test shows that the precipitators are highly sensitive, reliable, cheap and easy to operate

Biology and chemistry of three Pennsylvania lakes: responses to acid precipitation

Energy Technology Data Exchange (ETDEWEB)

Bradt, P.T.; Dudley, J.L.; Berg, M.B.; Barrasso, D.S.

1986-09-01

The biology and chemistry of three northeastern Pennsylvania lakes was studied from summer 1981 through summer 1983 to evaluate lakes with different sensitivities to acidification. At the acidified lake there were fewer phytoplankton and zooplankton species than at the moderately sensitive lakes. The most numerous plankton species in all three lakes are reportedly acid tolerant. Among the benthic macro-invertebrates (BMI) there were more acid tolerant Chironomidae at the acidified lake, but more acid intolerant Ephemeroptera and Mollusca and a higher wet weight at the least sensitive lake. There were no differences among the lakes' BMI mean total numbers or mean number of taxa. The fish community at the acidified lake was dominated by stunted Lepomis gibbosus, but L. machrochirous were most abundant in the other lakes. Principal component analysis suggested a shift in all three lakes over the sampling period toward combined lower pH, alkalinity, specific conductance, Ca and Mg and higher Al and Mn. Such chemical changes have been associated with acidification. The rate and extent of acidification appeared to be controlled by geological and hydrological characteristics of the drainage basins. 38 refs.

Effects of simulated acid precipitation and liming on pine litter decomposition

Energy Technology Data Exchange (ETDEWEB)

Ishac, Y.Z.; Hovland, J.

1976-01-01

The decomposition of withered lodgepole pine needles (Pinus contorta douglas) has been studied in a laboratory experiment. The needles were picked from trees that have been irrigated with simulated acid rain at pH 5.6 or 3.0. The soil beneath some of the trees was limed. The decomposition of the needles increased with temperature and incubation period. Liming of the soil retarded the decomposition of the needles that have been given rain at pH 3, while irrigation with 50 mm of water per month at pH 3 increased the decomposition compared with 25 mm/month. When needles were incubated in dilute sulphuric acid, the decomposition was reduced at pH 1.8 compared to the decomposition at pH 3.5. At pH 1.0 no decomposition occurred. Fungi were isolated from the needles. The different treatments did not seem to affect the composition of the fungal flora of the needles. The fungi were tested for their ability to decompose cellulose. The four most active cellulose decomposeres were Trichoderma harzianum, Coniothyrium sp., Cladosporium macrocarpum, and a sterile white mycelium. T. harzianum seemed to be more tolerant to acid conditions than the other fungi.

Global Precipitation Measurement. Report 7; Bridging from TRMM to GPM to 3-Hourly Precipitation Estimates

Science.gov (United States)

Shepherd, J. Marshall; Smith, Eric A.; Adams, W. James (Editor)

2002-01-01

Historically, multi-decadal measurements of precipitation from surface-based rain gauges have been available over continents. However oceans remained largely unobserved prior to the beginning of the satellite era. Only after the launch of the first Defense Meteorological Satellite Program (DMSP) satellite in 1987 carrying a well-calibrated and multi-frequency passive microwave radiometer called Special Sensor Microwave/Imager (SSM/I) have systematic and accurate precipitation measurements over oceans become available on a regular basis; see Smith et al. (1994, 1998). Recognizing that satellite-based data are a foremost tool for measuring precipitation, NASA initiated a new research program to measure precipitation from space under its Mission to Planet Earth program in the 1990s. As a result, the Tropical Rainfall Measuring Mission (TRMM), a collaborative mission between NASA and NASDA, was launched in 1997 to measure tropical and subtropical rain. See Simpson et al. (1996) and Kummerow et al. (2000). Motivated by the success of TRMM, and recognizing the need for more comprehensive global precipitation measurements, NASA and NASDA have now planned a new mission, i.e., the Global Precipitation Measurement (GPM) mission. The primary goal of GPM is to extend TRMM's rainfall time series while making substantial improvements in precipitation observations, specifically in terms of measurement accuracy, sampling frequency, Earth coverage, and spatial resolution. This report addresses four fundamental questions related to the transition from current to future global precipitation observations as denoted by the TRMM and GPM eras, respectively.

Self-organizing map network-based precipitation regionalization for the Tibetan Plateau and regional precipitation variability

Science.gov (United States)

Wang, Nini; Yin, Jianchuan

2017-12-01

A precipitation-based regionalization for the Tibetan Plateau (TP) was investigated for regional precipitation trend analysis and frequency analysis using data from 1113 grid points covering the period 1900-2014. The results utilizing self-organizing map (SOM) network suggest that four clusters of precipitation coherent zones can be identified, including the southwestern edge, the southern edge, the southeastern region, and the north central region. Regionalization results of the SOM network satisfactorily represent the influences of the atmospheric circulation systems such as the East Asian summer monsoon, the south Asian summer monsoon, and the mid-latitude westerlies. Regionalization results also well display the direct impacts of physical geographical features of the TP such as orography, topography, and land-sea distribution. Regional-scale annual precipitation trend as well as regional differences of annual and seasonal total precipitation were investigated by precipitation index such as precipitation concentration index (PCI) and Standardized Anomaly Index (SAI). Results demonstrate significant negative long-term linear trends in southeastern TP and the north central part of the TP, indicating arid and semi-arid regions in the TP are getting drier. The empirical mode decomposition (EMD) method shows an evolution of the main cycle with 4 and 12 months for all the representative grids of four sub-regions. The cross-wavelet analysis suggests that predominant and effective period of Indian Ocean Dipole (IOD) on monthly precipitation is around ˜12 months, except for the representative grid of the northwestern region.

Magnetic behavior of nickel ferrite nanoparticles prepared by co-precipitation route

International Nuclear Information System (INIS)

Maaz, K.; Mashiatullah, A.; Javed, T.; Ali, G.; Karim, S.

2008-01-01

Magnetic nanoparticles of nickel ferrite (NiFe/sub 2/O/sub 4/) have been synthesized by co-precipitation route using stable ferric and nickel salts with sodium hydroxide as the precipitating agent and oleic acid as the surfactant. X-ray Diffraction (XRD) and Transmission Electron Microscope (TEM) analyses confirmed the formation of single phase nickel ferrite nanoparticles in the range 8-28 nm. The size of the particles was observed to be increasing linearly with increasing annealing temperature of the sample. Typical blocking effects were observed below -225 K for all the prepared samples. The superparamagnetic blocking temperature was found to be continuously increasing with increasing particle sizes that has been attributed to the increased effective anisotropy of the nanoparticles. The saturation moment of all the samples was found much below the bulk value of nickel ferrite that has been attributed to the disordered surface spins of these nanoparticles. (author)

Waste acid detoxification and reclamation: Phase 1, Project planning and concept development

Energy Technology Data Exchange (ETDEWEB)

Stewart, T.L.; Brouns, T.M.

1988-02-01

The objectives of this project are to develop processes for reducing the volume, quantity, and toxicity of metal-bearing waste acids. The primary incentives for implemeting these types of waste minimization processes are regulatory and economic in that they meet requirements in the Resource Conservation and Recovery Act and reduce the cost for treatment, storage, and disposal. Two precipitation processes and a distillation process are being developed to minimize waste from fuel fabrication operations, which comprise a series of metal-finishing operations. Waste process acids, such as HF/--/HNO/sub 3/ etch solutions contianing Zr as a major metal impurity and HNO/sub 3/ strip solutions containing Cu as a major metal impurity, are detoxified and reclaimed by concurrently precipitating heavy metals and regenerating acid for recycle. Acid from a third waste acid stream generated from chemical milling operations will be reclaimed using distillation. This stream comprises HNO/sub 3/ and H/sub 2/SO/sub 4/ which contains U as the major metal impurity. Distillation allows NO/sub 3//sup /minus// to be displaced by SO/sub 4//sup /minus/2/ in metal salts; free HNO/sub 3/ is then vaporized from the U-bearing sulfate stream. Uranium can be recovered from the sulfate stream in downstream precipitation step. These waste minimization processes were developed to meet Hanford's fuel fabrication process needs. 7 refs., 4 figs., 1 tab.

Waste acid detoxification and reclamation: Phase 1, Project planning and concept development

International Nuclear Information System (INIS)

Stewart, T.L.; Brouns, T.M.

1988-02-01

The objectives of this project are to develop processes for reducing the volume, quantity, and toxicity of metal-bearing waste acids. The primary incentives for implemeting these types of waste minimization processes are regulatory and economic in that they meet requirements in the Resource Conservation and Recovery Act and reduce the cost for treatment, storage, and disposal. Two precipitation processes and a distillation process are being developed to minimize waste from fuel fabrication operations, which comprise a series of metal-finishing operations. Waste process acids, such as HF/--/HNO 3 etch solutions contianing Zr as a major metal impurity and HNO 3 strip solutions containing Cu as a major metal impurity, are detoxified and reclaimed by concurrently precipitating heavy metals and regenerating acid for recycle. Acid from a third waste acid stream generated from chemical milling operations will be reclaimed using distillation. This stream comprises HNO 3 and H 2 SO 4 which contains U as the major metal impurity. Distillation allows NO 3 /sup /minus// to be displaced by SO 4 /sup /minus/2/ in metal salts; free HNO 3 is then vaporized from the U-bearing sulfate stream. Uranium can be recovered from the sulfate stream in downstream precipitation step. These waste minimization processes were developed to meet Hanford's fuel fabrication process needs. 7 refs., 4 figs., 1 tab

Studies of Tc oxidation states in humic acid solutions

International Nuclear Information System (INIS)

Wang Bo; Liu Dejun; Yao Jun

2011-01-01

The oxidation state of Tc is an important aspect of the speciation in groundwater which contained organic substances due to it control the precipitation, complexation, sorption and colloid formation behavior of the Tc under HWL geological disposal conditions. In present work, the oxidation states of Tc were investigated using the LaCl 3 coagulation method and solution extraction method in aqueous solutions in which the humic acid concentration range is from 0 to 20 mg/L and the Tc (VII) concentration is about 10 -8 mol/L. The radiocounting of 99 Tc was determined using liquid scintillation spectrometry. The humic acid will influence the radiocounting ratio of 99 Tc apparently, however, the quenching effect can be restrained once keep the volume of the cocktail to about twenty times of the sample volume. The LaCl 3 coagulation method was carried out for the investigation of Tc oxidation states in humic acid aqueous systems at about pH 8. The tetraphenylarsonium chloride (TPA)-chloroform extraction method was used also simultaneously to investigation the concentrations of Tc (IV) and Tc (VII) for the availability of the LaCl 3 precipitation method, and the experimental results demonstrate that tetravalent technetium and pertechnetate concentration are well agreement with the LaCl 3 precipitation method. These two experimental results demonstrated that Tc (VII) is very stable in the Tc (VII)-humic acid system during a 350 days experimental period, and the Tc (IV) concentrations are very lower, that is indicate that there didn't oxidizing reactions between the Fluka humic acid and Tc (VII) in aqueous solutions under anaerobic conditions. That means the presence of humic acids even in anaerobic groundwater is disadvantage for the retardance of radionuclides. (authors)

Aquifer restoration system improvement using an acid fluid purge

International Nuclear Information System (INIS)

Hodder, E.A.; Peck, C.A.

1992-01-01

The implementation of a water pump acid purge procedure at a free-phase liquid hydrocarbon recovery site has increased water pump operational run times and improved the effectiveness of the aquifer restoration effort. Before introduction of this technique, pumps at some locations would fail within 14 days of operation due to CaSO 4 .2H 2 O (calcium sulfate) precipitate fouling. After acid purge implementation at these locations, pump operational life improved to an average of over 110 days. Other locations, where pump failures would occur within one month, were improved to approximately six months of operation. The increase in water pump run time has also improved the liquid hydrocarbon recovery rate by 2,000 gallons per day; representing a 20% increase for the aquifer restoration system. Other concepts tested in attempts to prolong pump life included: specially designed electric submersible pumps, submersible pump shrouds intended to reduce the fluid pressure shear that enhances CaSO 4 .2H 2 O precipitation, and high volume pneumatic gas lift pumps. Due to marginal pump life improvement or other undesirable operational features, these concepts were primarily ineffective. The purge apparatus utilizes an acid pump, hose, and discharge piping to deliver the solution directly into the inlet of an operating water pump. The water pumps used for this activity require stainless steel construction with Teflon or other acid resistant bearings and seals. Purges are typically conducted before sudden discharge pressure drops (greater than 15 psig) occur for the operating water pump. Depending on volume of precipitate accumulation and pump type, discharge pressure is restored after introduction of 10 to 40 gallons of hydrochloric acid solution. The acid purge procedure outlined herein eliminates operational downtime and does not require well head pump removal and the associated costs of industry cleaning procedures

Mobility of radiocaesium in boreal forest ecosystems: Influence of precipitation chemistry

Energy Technology Data Exchange (ETDEWEB)

Steinnes, E. [Department of Chemistry, Norwegian University of Science and Technology (Norway); Gjelsvik, R.; Skuterud, L.; Thoerring, H. [Norwegian Radiation Protection Authority (Norway)

2014-07-01

Mobility and plant uptake of Cs in soils is generally limited by the presence of clay minerals in the soil. However, cations supplied by precipitation may substantially influence the mobility of radiocaesium in natural surface soil and subsequent transfer to food chains. The chemical composition of precipitation shows substantial variation among different areas in Norway for two main reasons. At sites close to the coast the atmospheric supply of marine cations and anions is many-fold greater than in regions shielded from marine influence by mountains. The southernmost part of the country has been, and still is, substantially affected by soil acidification due to long-range atmospheric transport of acidifying substances from areas elsewhere in Europe. This may explain a much higher greater uptake of {sup 137}Cs from the Chernobyl accident in moose in this region than elsewhere (Steinnes et al., 2009), in spite of the fact that some areas farther north received substantially greater fallout. Similarly a much greater transfer of {sup 137}Cs to natural birch forest vegetation is evident from the more acidified soils in the south than in comparable ecosystems elsewhere in the country (Thoerring et al., 2012). Repeated recordings of activity levels in natural surface soils showed faster leaching of Chernobyl {sup 137}Cs relative to inland areas not only in the south but also in coastal areas farther north (Gjelsvik and Steinnes, 2013), indicating that the amounts of marine cations in precipitation also has an appreciable effect on the Cs leaching. The geographical leaching differences still became less prominent with time. Recent lysimeter experiments with undisturbed soil columns obtained from an area receiving high radiocaesium deposition from the Chernobyl accident, applying precipitation with ionic composition characteristic of the different regions mentioned above, did not change the current depth distribution of {sup 137}Cs. However, acidic precipitation increased

A New Multichelating Acid System for High-Temperature Sandstone Reservoirs

Directory of Open Access Journals (Sweden)

Nianyin Li

2015-01-01

Full Text Available Sandstone reservoir acidizing is a complex and heterogeneous acid-rock reaction process. If improper acid treatment is implemented, further damage can be induced instead of removing the initial plug, particularly in high-temperature sandstone reservoirs. An efficient acid system is the key to successful acid treatment. High-temperature sandstone treatment with conventional mud acid system faces problems including high acid-rock reaction rate, short acid effective distance, susceptibility to secondary damage, and serious corrosion to pipelines. In this paper, a new multichelating acid system has been developed to overcome these shortcomings. The acid system is composed of ternary weak acid, organic phosphonic chelating agent, anionic polycarboxylic acid chelating dispersant, fluoride, and other assisted additives. Hydrogen ion slowly released by multistage ionization in ternary weak acid and organic phosphonic within the system decreases the concentration of HF to achieve retardation. Chelating agent and chelating dispersant within the system inhibited anodic and cathodic reaction, respectively, to protect the metal from corrosion, while chelating dispersant has great chelating ability on iron ions, restricting the depolarization reaction of ferric ion and metal. The synergic effect of chelating agent and chelating dispersant removes sulfate scale precipitation and inhibits or decreases potential precipitation such as CaF2, silica gel, and fluosilicate. Mechanisms of retardation, corrosion-inhibition, and scale-removing features have been discussed and evaluated with laboratory tests. Test results indicate that this novel acid system has good overall performance, addressing the technical problems and improving the acidizing effect as well for high-temperature sandstone.

Intercomparison of spaceborne precipitation radars and its applications in examining precipitation-topography relationships in the Tibetan Plateau

Science.gov (United States)

Tang, G.; Gao, J.; Long, D.

2017-12-01

Precipitation is one of the most important components in the water and energy cycles. Spaceborne radars are considered the most direct technology for observing precipitation from space since 1998. This study compares and evaluates the only three existing spaceborne precipitation radars, i.e., the Ku-band precipitation radar (TRMM PR), the W-band Cloud Profiling Radar (CloudSat CPR), and the Ku/Ka-band Dual-frequency Precipitation Radar (GPM DPR). In addition, TRMM PR and GPM DPR are evaluated against hourly rain gauge data in Mainland China. The Tibetan Plateau (TP) is known as the Earth's third pole where precipitation is affected profoundly by topography. However, ground gauges are extremely sparse in the TP, and spaceborne radars can provide valuable data with relatively high accuracy. The relationships between precipitation and topography over the TP are investigated using 17-year TRMM PR data and 2-year GPM DPR data, in combination with rain gauge data. Results indicate that: (1) DPR and PR agree with each other and correlate very well with gauges in Mainland China. DPR improves light precipitation detectability significantly compared with PR. However, DPR high sensitivity scans (HS) deviates from DPR normal and matched scans (NS and MS) and PR in the comparison based on global coincident events and rain gauges in China; (2) CPR outperforms the other two radars in terms of light precipitation detection. In terms of global snowfall estimation, DPR and CPR show very different global snowfall distributions originating from different frequencies, retrieval algorithms, and sampling characteristics; and (3) Precipitation generally decreases exponentially with increasing elevation in the TP. The precipitation-topography relationships are regressed using exponential fitting in seventeen river basins in the TP with good coefficients of determination. Due to the short time span of GPM DPR, the relationships based on GPM DPR data are less robust than those derived from

STAMMEX high resolution gridded daily precipitation dataset over Germany: a new potential for regional precipitation climate research

Science.gov (United States)

Zolina, Olga; Simmer, Clemens; Kapala, Alice; Mächel, Hermann; Gulev, Sergey; Groisman, Pavel

2014-05-01

We present new high resolution precipitation daily grids developed at Meteorological Institute, University of Bonn and German Weather Service (DWD) under the STAMMEX project (Spatial and Temporal Scales and Mechanisms of Extreme Precipitation Events over Central Europe). Daily precipitation grids have been developed from the daily-observing precipitation network of DWD, which runs one of the World's densest rain gauge networks comprising more than 7500 stations. Several quality-controlled daily gridded products with homogenized sampling were developed covering the periods 1931-onwards (with 0.5 degree resolution), 1951-onwards (0.25 degree and 0.5 degree), and 1971-2000 (0.1 degree). Different methods were tested to select the best gridding methodology that minimizes errors of integral grid estimates over hilly terrain. Besides daily precipitation values with uncertainty estimates (which include standard estimates of the kriging uncertainty as well as error estimates derived by a bootstrapping algorithm), the STAMMEX data sets include a variety of statistics that characterize temporal and spatial dynamics of the precipitation distribution (quantiles, extremes, wet/dry spells, etc.). Comparisons with existing continental-scale daily precipitation grids (e.g., CRU, ECA E-OBS, GCOS) which include considerably less observations compared to those used in STAMMEX, demonstrate the added value of high-resolution grids for extreme rainfall analyses. These data exhibit spatial variability pattern and trends in precipitation extremes, which are missed or incorrectly reproduced over Central Europe from coarser resolution grids based on sparser networks. The STAMMEX dataset can be used for high-quality climate diagnostics of precipitation variability, as a reference for reanalyses and remotely-sensed precipitation products (including the upcoming Global Precipitation Mission products), and for input into regional climate and operational weather forecast models. We will present

Experimental study of diffuse auroral precipitations

International Nuclear Information System (INIS)

Mouaia, K.

1983-01-01

First chapter is devoted to low energy electron precipitation in the evening sector of the auroral magnetosphere, during quiet and disturbed magnetic periods. Four subjects are studied in detail: the latitude distribution of the varied auroral forms and their relations to external magnetosphere; the time coefficients related to precipitations, the form and the dynamic of the diffuse precipitation equatorial frontier; the precipitation effect on the ionosphere concentration. The last part of the chapter shows that the plasma convection in the magnetosphere, associated to wave-particle interactions near the equatorial accounts for the principal characteristics of the evening sector diffuse electronic precipitations. The second chapter deals with subauroral precipitations of low energy ions, after the magnetospheric substorms, in the high latitude regions of the morning sector [fr

Some observations of the pH of precipitation elements

Energy Technology Data Exchange (ETDEWEB)

Landsberg, H

1954-01-01

A year of observations of pH values of individual rain drops and snowflakes near Boston, Mass., showed acidic values ranging from 3 to 5.5 with a mean value of 4. There was no systematic relation between pH and the duration of rainfall. Drizzle and light rain had the lowest values, heavy rain and solid precipitation had the highest. There is a tendency for smaller drops to have lower values of pH than the larger ones. Measurements of dew and frost showed also a range from 3 to 5.5 with a mean value of 4.3.

Lipid-Based Formulations Can Enable the Model Poorly Water-Soluble Weakly Basic Drug Cinnarizine to Precipitate in an Amorphous-Salt Form during in Vitro Digestion

DEFF Research Database (Denmark)

Khan, Jamal; Rades, Thomas; Boyd, Ben J

2016-01-01

The tendency for poorly water-soluble weakly basic drugs to precipitate in a noncrystalline form during the in vitro digestion of lipid-based formulations (LBFs) was linked to an ionic interaction between drug and fatty acid molecules produced upon lipid digestion. Cinnarizine was chosen as a model...... from the starting free base crystalline material to the hydrochloride salt, thus supporting the case that ionic interactions between weak bases and fatty acid molecules during digestion are responsible for producing amorphous-salts upon precipitation. The conclusion has wide implications...... weakly basic drug and was dissolved in a medium-chain (MC) LBF, which was subject to in vitro lipolysis experiments at various pH levels above and below the reported pKa value of cinnarizine (7.47). The solid-state form of the precipitated drug was analyzed using X-ray diffraction (XRD), Fourier...

Liquid waste processing from plutonium (III) oxalate precipitation

International Nuclear Information System (INIS)

Esteban, A.; Cassaniti, P.; Orosco, E.H.

1990-01-01

Plutonium (III) oxalate filtrates contain about 0.2M oxalic acid, 0.09M ascorbic acid, 0.05M hydrazine, 1M nitric acid and 20-100 mg/l of plutonium. The developed treatment of liquid wastes consist in two main steps: a) Distillation to reduce up to 10% of the initial volume and refluxing to destroy organic material. Then, the treated solution is suitable to adjust the plutonium at the tetravalent state by addition of hydrogen peroxide and the nitric molarity up to 8.6M. b) Recovery and purification of plutonium by anion exchange using two columns in series containing Dowex 1-X4 resin. With the proposed process, it is possible to transform 38 litres of filtrates with 40mg/l of Pu into 0.1 l of purified solution with 15-20g/l of Pu. This solution is suitable to be recycled in the Pu (III) oxalate precipitation process. This process has several potential advantages over similar liquid waste treatments. These include: 1) It does not increase the liquid volume. 2) It consumes only few reagents. 3) The operations involved are simple, requiring limited handling and they are feasible to automatization. 4) The Pu recovery factor is about 99%. (Author) [es

Long-term stability of earthen materials in contact with acidic tailings solutions

International Nuclear Information System (INIS)

Peterson, S.R.; Erikson, R.L.; Gee, G.W.

1982-11-01

The objectives of the studies documented in this report were to use experimental and geochemical computer modeling tools to assess the long-term environmental impact of leachate movement from acidic uranium mill tailings. Liner failure (i.e., an increase in the permeability of the liner material) was not found to be a problem when various acidic tailings solutions leached through liner materials for periods up to 3 years. On the contrary, materials that contained over 30% clay showed a decrease in permeability with time in the laboratory columns. The high clay materials tested appear suitable for lining tailings impoundment ponds. The decreases in permeability are attributed to pore plugging resulting from the precipitation of minerals and solids. This precipitation takes place due to the increase in pH of the tailings solution brought about by the buffering capacity of the soil. Geochemical modeling predicts, and x-ray characterization confirms, that precipitation of solids from solution is occurring in the acidic tailings solution/liner interactions studied. In conclusion the same mineralogical changes and contaminant reactions predicted by geochemical modeling and observed in laboratory studies were found at a drained evaporation pond (Lucky Mc in Wyoming) with a 4 year history of acid attack

Continuous plutonium(IV) oxalate precipitation, filtration, and calcination process. [From product streams from Redox, Purex, or Recuplex solvent extraction plants

Energy Technology Data Exchange (ETDEWEB)

Beede, R L

1956-09-27

A continuous plutonium (IV) oxalate precipitation, filtration, and calcination process has been developed. Continuous and batch decomposition of the oxalate in the filtrates has been demonstrated. The processes have been demonstrated in prototype equipment. Plutonium (IV) oxalate was precipitated continuously at room temperature by the concurrent addition of plutonium (IV) nitrate feed and oxalic acid into the pan of a modified rotary drum filter. The plutonium (IV) oxalate was calcined to plutonium dioxide, which could be readily hydrofluorinated. Continuous decomposition of the oxalate in synthetic plutonium (IV) oxalate filtrates containing plutonium (IV) oxalate solids was demonstrated using co-current flow in a U-shaped reactor. Feeds containing from 10 to 100 g/1 Pu, as plutonium (IV) nitrate, and 1.0 to 6.5 M HNO/sub 3/, respectively, can be processed. One molar oxalic acid is used as the precipitant. Temperatures of 20 to 35/sup 0/C for the precipitation and filtration are satisfactory. Plutonium (IV) oxalate can be calcined at 300 to 400/sup 0/C in a screw-type drier-calciner to plutonium dioxide and hydrofluorinated at 450 to 550/sup 0/C. Plutonium dioxide exceeding purity requirements has been produced in the prototype equipment. Advantages of continuous precipitation and filtration are: uniform plutonium (IV) oxalate, improved filtration characteristics, elimination of heating and cooling facilities, and higher capacities through a single unit. Advantages of the screw-type drier-calciner are the continuous production of an oxide satisfactory for feed for the proposed plant vibrating tube hydrofluorinator, and ease of coupling continuous precipitation and filtration to this proposed hydrofluorinator. Continuous decomposition of oxalate in filtrates offers advantages in decreasing filtrate storage requirements when coupled to a filtrate concentrator. (JGB)

Extraction of Zinc and Manganese from Alkaline and Zinc-Carbon Spent Batteries by Citric-Sulphuric Acid Solution

Directory of Open Access Journals (Sweden)

Francesco Ferella

2010-01-01

Full Text Available The paper is focused on the recovery of zinc and manganese from alkaline and zinc-carbon spent batteries. Metals are extracted by sulphuric acid leaching in the presence of citric acid as reducing agent. Leaching tests are carried out according to a 24 full factorial design, and empirical equations for Mn and Zn extraction yields are determined from experimental data as a function of pulp density, sulphuric acid concentration, temperature, and citric acid concentration. The highest values experimentally observed for extraction yields were 97% of manganese and 100% of zinc, under the following operating conditions: temperature 40∘C, pulp density 20%, sulphuric acid concentration 1.8 M, and citric acid 40 g L-1. A second series of leaching tests is also performed to derive other empirical models to predict zinc and manganese extraction. Precipitation tests, aimed both at investigating precipitation of zinc during leaching and at evaluating recovery options of zinc and manganese, show that a quantitative precipitation of zinc can be reached but a coprecipitation of nearly 30% of manganese also takes place. The achieved results allow to propose a battery recycling process based on a countercurrent reducing leaching by citric acid in sulphuric solution.

Optimization of process parameters in precipitation for consistent quality UO{sub 2} powder production

Energy Technology Data Exchange (ETDEWEB)

Tiwari, S.K.; Reddy, A.L.V.; Venkataswamy, J.; Misra, M.; Setty, D.S.; Sheela, S.; Saibaba, N., E-mail: misra@nfc.gov.in [Nuclear Fuel Complex, Hyderabad (India)

2013-07-01

Nuclear reactor grade natural uranium dioxide powder is being produced through precipitation route, which is further processed before converting into sintered pellets used in the fabrication of PHWR fuel assemblies of 220 and 540 MWe type reactors. The process of precipitating Uranyl Nitrate Pure Solution (UNPS) is an important step in the UO{sub 2} powder production line, where in soluble uranium is transformed into solid form of Ammonium Uranate (AU), which in turn reflects and decides the powder characteristics. Precipitation of UNPS with vapour ammonia is being carried out in semi batch process and process parameters like ammonia flow rate, temperature, concentration of UNPS and free acidity of UNPS are very critical and decides the UO{sub 2} powder quality. Variation in these critical parameters influences powder characteristics, which in turn influences the sinterability of UO{sub 2} powder. In order to get consistent powder quality and sinterability the critical parameter like ammonia flow rate during precipitation is studied, optimized and validated. The critical process parameters are controlled through PLC based automated on-line data acquisition systems for achieving consistent powder quality with increased recovery and production. The present paper covers optimization of process parameters and powder characteristics. (author)

Evaluation of precipitates used in strainer head loss testing. Part I. Chemically generated precipitates

International Nuclear Information System (INIS)

Bahn, Chi Bum; Kasza, Ken E.; Shack, William J.; Natesan, Ken; Klein, Paul

2009-01-01

The purpose of the current program was to evaluate the properties of chemical precipitates proposed by industry that have been used in sump strainer head loss testing. Specific precipitates that were evaluated included aluminum oxyhydroxide (AlOOH) and sodium aluminum silicate (SAS) prepared according to the procedures in WCAP-16530-NP, along with precipitates formed from injecting chemicals into the test loop according to the procedure used by one sump strainer test vendor for U.S. pressurized water reactors. The settling rates of the surrogate precipitates are strongly dependent on their particle size and are reasonably consistent with those expected from Stokes' Law or colloid aggregation models. Head loss tests showed that AlOOH and SAS surrogates are quite effective in increasing the head loss across a perforated pump inlet strainer that has an accumulated fibrous debris bed. The characteristics of aluminum hydroxide precipitate using sodium aluminate were dependent on whether it was formed in high-purity or ordinary tap water and whether excess silicate was present or not.

Centrifugal washing and recovery as an improved method for obtaining lignin precipitated from South African kraft mill black liquor

CSIR Research Space (South Africa)

Namane, M

2015-10-01

Full Text Available This study describes centrifugal recovery as an improved method for collection of lignin isolated from black liquor obtained from a South African kraft mill. Precipitation of lignin was achieved by utilising 6 M sulphuric acid. Recovery...

Effective assimilation of global precipitation: simulation experiments

Directory of Open Access Journals (Sweden)

Guo-Yuan Lien

2013-07-01

Full Text Available Past attempts to assimilate precipitation by nudging or variational methods have succeeded in forcing the model precipitation to be close to the observed values. However, the model forecasts tend to lose their additional skill after a few forecast hours. In this study, a local ensemble transform Kalman filter (LETKF is used to effectively assimilate precipitation by allowing ensemble members with better precipitation to receive higher weights in the analysis. In addition, two other changes in the precipitation assimilation process are found to alleviate the problems related to the non-Gaussianity of the precipitation variable: (a transform the precipitation variable into a Gaussian distribution based on its climatological distribution (an approach that could also be used in the assimilation of other non-Gaussian observations and (b only assimilate precipitation at the location where at least some ensemble members have precipitation. Unlike many current approaches, both positive and zero rain observations are assimilated effectively. Observing system simulation experiments (OSSEs are conducted using the Simplified Parametrisations, primitivE-Equation DYnamics (SPEEDY model, a simplified but realistic general circulation model. When uniformly and globally distributed observations of precipitation are assimilated in addition to rawinsonde observations, both the analyses and the medium-range forecasts of all model variables, including precipitation, are significantly improved as compared to only assimilating rawinsonde observations. The effect of precipitation assimilation on the analyses is retained on the medium-range forecasts and is larger in the Southern Hemisphere (SH than that in the Northern Hemisphere (NH because the NH analyses are already made more accurate by the denser rawinsonde stations. These improvements are much reduced when only the moisture field is modified by the precipitation observations. Both the Gaussian transformation and

Encoding information into precipitation structures

International Nuclear Information System (INIS)

Martens, Kirsten; Bena, Ioana; Droz, Michel; Rácz, Zoltan

2008-01-01

Material design at submicron scales would be profoundly affected if the formation of precipitation patterns could be easily controlled. It would allow the direct building of bulk structures, in contrast to traditional techniques which consist of removing material in order to create patterns. Here, we discuss an extension of our recent proposal of using electrical currents to control precipitation bands which emerge in the wake of reaction fronts in A + + B – → C reaction–diffusion processes. Our main result, based on simulating the reaction–diffusion–precipitation equations, is that the dynamics of the charged agents can be guided by an appropriately designed time-dependent electric current so that, in addition to the control of the band spacing, the width of the precipitation bands can also be tuned. This makes straightforward the encoding of information into precipitation patterns and, as an amusing example, we demonstrate the feasibility by showing how to encode a musical rhythm

Hydrothermally Stable Fe–W–Ti SCR Catalysts Prepared by Deposition–Precipitation

DEFF Research Database (Denmark)

Putluru, Siva Sankar Reddy; Schill, Leonhard; Mossin, Susanne

2014-01-01

Fe/TiO2 based catalysts were prepared by incipient wetness impregnation and deposition–precipitation (DP). The catalysts were characterized by activity measurements, N2 physisorption, X-ray powder diffraction, electron paramagnetic resonance spectroscopy, energy dispersive X-ray spectroscopy, H2......-temperature programmed reduction and NH3-temperature programmed desorption. The 3 wt% Fe–10 wt% WO3/TiO2 (3Fe–10WTi-DP) catalyst prepared by DP using ammonium carbamate as a precipitating agent was found to be the most active and hydrothermally stable with 11 vol% H2O in air at 650 °C for 3 h....... The hydrothermal stability of the catalyst can be attributed to the retained crystal structure, and mild change in acidic and redox properties of the catalyst. Furthermore, hydrothermal stability of the 3Fe–10WTi-DP catalyst is competitive with that of 3Fe–ZSM-5 and much better than 3V2O5–10WO3–TiO2 catalysts...

The development of precisely analytical method for the concentrated boric acid solution in the NPP systems

Energy Technology Data Exchange (ETDEWEB)

Sung, G. B.; Jung, K. H.; Kang, D. W. [KEPRI, Taejon (Korea, Republic of); Park, C. S. [KEPCO, Taejon (Korea, Republic of)

1999-05-01

Boric acid is used for reactivity control in nuclear reactors, which frequently results in leftover boric acid. This extra boric acid is stored in boric acid storage tank after the concentration process by boric acid evaporator. Apart from this excess, highly concentrated boric acid is stored in safety-related boric acid storage tank. Accordingly, proper maintenance of these boric acid is one of the greatest safety concerns. The solubility of boric acid decreases with decreasing temperature resulting in its precipitation. Consequently, the temperature of boric acid storage tanks is maintained at high temperature. The following analysis should be also performed at the similar temperature to prevent the formation of boric acid precipitation, which is difficult to achieve affecting the accuracy of analytical results. This paper presents a new sampling and measuring technique that makes up for the difficulties mentioned above and shows several advantages including improved reliability and short analysis time. This method is based on gravimetry and dilution method and is expected to be widely used in field application.

Effect of microtopography on isotopic composition of methane in porewater and efflux at a boreal peatland

Energy Technology Data Exchange (ETDEWEB)

Dorodnikov, M.; Wilmking, M. [Greifswald Univ. (Georgia). Inst. of Botany and Landscape Ecology; Marushchak, M.; Biasi, C. [Univ. of Eastern Finland, Kuopio (Finland). Dept. of Environmental Science, Bioteknia 2], E-mail: maxim.dorodnikov@uef.fi

2013-09-01

The application of stable isotopes is an approach to identify pathways of methanogenesis, methane (CH{sub 4}) oxidation and transport in peatlands. We measured the stable C isotopic characteristics ({delta}C-13) of CH{sub 4} in peat profiles below hummocks, lawns and hollows of a Finnish mire to study the patterns of CH{sub 4} turnover. Porewater CH{sub 4} concentrations ([CH{sub 4}]; at 0.5-2 m) increased with depth below all microforms. Emissions of CH{sub 4} from hummocks were the lowest, and increased with the increasing water-saturated zone, being {approx}10 times higher from hollows. Thus, the microtopography of the peatland did not affect the porewater [CH{sub 4}] in the water-saturated part of the peat profile, but the CH{sub 4} emissions were affected due to differences in the oxidative potential of the microforms. There was a decrease in {delta}C-13-CH{sub 4} with depth below all microforms indicating dominance of CO{sub 2}-reduction over acetate cleavage pathway of methanogenesis at deep peat layers. However, estimated potential portions of transported CH{sub 4} comprised 50%-70% of the {delta}C-13-CH{sub 4} enrichment on microforms at the 0.5-m depth, hereby masking the acetate cleavage pathway of methanogenesis. Stable C composition ({delta}C-13) of CH{sub 4} proved to be a suitable (but not sufficient) tool to differentiate between types of methanogenesis in continuously water-saturated layers below microforms of a peatland. Combined flux-based and multi-isotopic approaches are needed to better understand the CH{sub 4} turnover process. (orig.)

A test for Improvement of high resolution Quantitative Precipitation Estimation for localized heavy precipitation events

Science.gov (United States)

Lee, Jung-Hoon; Roh, Joon-Woo; Park, Jeong-Gyun

2017-04-01

Accurate estimation of precipitation is one of the most difficult and significant tasks in the area of weather diagnostic and forecasting. In the Korean Peninsula, heavy precipitations are caused by various physical mechanisms, which are affected by shortwave trough, quasi-stationary moisture convergence zone among varying air masses, and a direct/indirect effect of tropical cyclone. In addition to, various geographical and topographical elements make production of temporal and spatial distribution of precipitation is very complicated. Especially, localized heavy rainfall events in South Korea generally arise from mesoscale convective systems embedded in these synoptic scale disturbances. In weather radar data with high temporal and spatial resolution, accurate estimation of rain rate from radar reflectivity data is too difficult. Z-R relationship (Marshal and Palmer 1948) have adapted representatively. In addition to, several methods such as support vector machine (SVM), neural network, Fuzzy logic, Kriging were utilized in order to improve the accuracy of rain rate. These methods show the different quantitative precipitation estimation (QPE) and the performances of accuracy are different for heavy precipitation cases. In this study, in order to improve the accuracy of QPE for localized heavy precipitation, ensemble method for Z-R relationship and various techniques was tested. This QPE ensemble method was developed by a concept based on utilizing each advantage of precipitation calibration methods. The ensemble members were produced for a combination of different Z-R coefficient and calibration method.

Impact of Precipitation Fluctuation on Desert-Grassland ANPP

Directory of Open Access Journals (Sweden)

Liangxu Liu

2016-11-01

Full Text Available Precipitation change has significantly influenced annual net primary productivity (ANPP at either annual or seasonal scales in desert steppes in arid and semi-arid regions. In order to reveal the process of precipitation driving ANPP at different time scales, responses of different ANPP levels to the inter-annual and intra-annual precipitation fluctuations were analyzed. ANPP was reversed by building a ground reflectance spectrum model, from 2000 to 2015, using the normalized differential vegetation index of the Moderate-Resolution Imaging Spectroradiometer (MODIS-NDVI data at 250 m × 250 m spatial resolution. Since the description of the differently expressing forms of precipitation are not sufficient in former studies in order to overcome the deficiency of former studies, in this study, intra-annual precipitation fluctuations were analyzed not only with precipitation of May–August, June–August, July–August, and August, respectively, which have direct influence on vegetation productivity within the year, but quantitative description, vector precipitation (R, concentration ratio (Cd, and concentration period (D, were also used to describe the overall characteristics of intra-annual precipitation fluctuations. The concentration ratio and the maximum precipitation period of the intra-annual precipitation were represented by using monthly precipitation. The results showed that: (1 in the period from 1971 to 2015, the maximum annual precipitation is 3.76 times that of the minimum in the Urat desert steppe; (2 vector precipitation is more significantly related to ANPP (r = 0.7724, p = 0.000 compared to meteorological annual precipitation and real annual precipitation influence; and (3 annual precipitation is almost concentrated in 5–8 months and monthly precipitation accumulation has significantly effected ANPP, especially in the period of June–August, since the vegetation composition in the study area was mainly sub-shrubs and perennial

Interfacial Precipitation of Phosphate on Hematite and Goethite

Directory of Open Access Journals (Sweden)

Lijun Wang

2018-05-01

Full Text Available Adsorption and subsequent precipitation of dissolved phosphates on iron oxides, such as hematite and goethite, is of considerable importance in predicting the bioavailability of phosphates. We used in situ atomic force microscopy (AFM to image the kinetic processes of phosphate-bearing solutions interacting with hematite or goethite surfaces. The nucleation of nanoparticles (1.0–4.0 nm in height of iron phosphate (Fe(III-P phases, possibly an amorphous phase at the initial stages, was observed during the dissolution of both hematite and goethite at the earliest crystallization stages. This was followed by a subsequent aggregation stage where larger particles and layered precipitates are formed under different pH values, ionic strengths, and organic additives. Kinetic analysis of the surface nucleation of Fe-P phases in 50 mM NH4H2PO4 at pH 4.5 showed the nucleation rate was greater on goethite than hematite. Enhanced goethite and hematite dissolution in the presence of 10 mM AlCl3 resulted in a rapid increase in Fe-P nucleation rates. A low concentration of citrate promoted the nucleation, whereas nucleation was inhibited at higher concentrations of citrate. By modeling using PHREEQC, calculated saturation indices (SI showed that the three Fe(III-P phases of cacoxenite, tinticite, and strengite may be supersaturated in the reacted solutions. Cacoxenite is predicted to be more thermodynamically favorable in all the phosphate solutions if equilibrium is reached with respect to hematite or goethite, although possibly only amorphous precipitates were observed at the earliest stages. These direct observations at the nanoscale may improve our understanding of phosphate immobilization in iron oxide-rich acid soils.

Effects of alteration product precipitation on glass dissolution

Energy Technology Data Exchange (ETDEWEB)

Strachan, Denis M.; Neeway, James J.

2014-06-01

Understanding the mechanisms that control the durability of nuclear waste glass is paramount if reliable models are to be constructed so that the glass dissolution rate in a given geological repository can be calculated. Presently, it is agreed that (boro)silicate glasses dissolve in water at a rate dependent on the solution concentration of orthosilicic acid (H₄SiO₄) with higher [H₄SiO₄] leading to lower dissolution rates. Once the reaction has slowed as a result of the buildup of H₄SiO₄, another increase in the rate has been observed that corresponds to the precipitation of certain silica-bearing alteration products. However, it has also been observed that the concentration of silica-bearing solution species does not significantly decrease, indicating saturation, while other glass tracer elements concentrations continue to increase, indicating that the glass is still dissolving. In this study, we have used the Geochemist’s Workbench code to investigate the relationship between glass dissolution rates and the precipitation rate of a representative zeolitic silica-bearing alteration product, analcime [Na(AlSi₂O₆)∙H₂O]. To simplify the calculations, we suppressed all alteration products except analcime, gibbsite (Al(OH)₃), and amorphous silica. The pseudo-equilibrium-constant matrix for amorphous silica was substituted for the glass pseudo-equilibrium-constant matrix because it has been shown that silicate glasses act as a silica-only solid with respect to kinetic considerations. In this article, we present the results of our calculations of the glass dissolution rate at different values for the analcime precipitation rate constant and the effects of varying the glass dissolution rate constant at a constant analcime precipitation rate constant. From the simulations we conclude, firstly, that the rate of glass dissolution is dependent on the kinetics of

Kinetic and analytical study on precipitation reactions with 110AgNO3 of some di(β-chloroethyl)amine derivatives and hydrochlorides with esters of N-(p-aminobenzoyl)-L-aspartic acid as carriers from dimethylformamide - water solution

International Nuclear Information System (INIS)

Cecal, Al.; Sunel, V.; Ghimiciu, L.

1983-01-01

The kinetics of precipitation reactions with 110 AgNO 3 of some di(β-chloroethyl) amine derivates and hydrochlorides with esters of N-(p-aminobenzoyl)-L-aspartic acid as carriers in dimethylformamide-water mixture, were studied. The rate constants of these reactions were of the order of 10 -4 lxmol -1 xmin -1 . The concentrations of the corresponding hydrochloride solutions were measured by radiometric titration with 110 AgNO 3 solution of given concentration. (author)

To postpone the precipitation of manganese oxides in the degradation of tetrachloroethylene by controlling the permanganate concentration.

Science.gov (United States)

Yang, Weiwei; Qiu, Zhaofu; Zhao, Zhexuan; Lu, Shuguang; Sui, Qian; Gu, Xiaogang

2017-01-01

Controlled-release permanganate (CRP) is a relatively new technology used to treat contaminated groundwater. This study tested the encapsulation of permanganate using stearic acid to realize controlled-release properties. Batch experiments were conducted to investigate the performance of manganese oxides (MnO 2 ) in the reaction between CRP and the contaminant of interest: tetrachloroethylene (PCE). The results showed that higher ionic strengths (I = 0.1 mol/L) cause earlier precipitation of MnO 2 colloids. Using CRP to degrade PCE could decrease the amount of MnO 2 colloids produced and postpone precipitation compared to raw potassium permanganate (KMnO 4 ) under high ionic strength conditions by controlling the KMnO 4 concentration in the solution. The amount of MnO 2 colloids produced and the time of precipitation depended more on the CRP grain size than on the CRP mass ratio. Controlling the KMnO 4 concentration used in the reaction could control the formation of MnO 2 precipitates in the premise of guarantee the removal rate of PCE.

Polylactic acid organogel as versatile scaffolding technique