Download or read book Kinetics of Silica Condensation In Brines written by and published by . This book was released on 1976 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Homogeneous nucleation and growth of silica from brines supersaturated in silicic acid has been studied over a range of pH (4.5-6.7), temperature (75-105 C), salinity, and silicic acid concentration (700 to 1200 ppm as SiO2). The experimental technique involved analyses for molybdate-reactive silicic acid as a function of time after a supersaturated solution of H4SiO4 was prepared by mixing aliquots of a stock silicate solution with buffered brine. The isothermal rate of SiO2 condensation is a strong function of supersaturation (C/C{sub eq}), pH, and salinity. The overall kinetics follow what is expected from the general theory of phase transitions and are adequately described by the Volmer-Becker-Doring expressions for condensation from solution. At supersaturations less than about 3, an induction or transition time is observed. It amounts to several hundred minutes at supersaturations of about 2.0.
Download or read book Study of Silica Scaling from Geothermal Brines Final Report 15 November 1974 30 April 1977 written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Condensation of silica from brines supersaturate in silicic acid was studied over a range of pH (4.5 to 6.5), temperature (75 to 105°C), salinity, and silicic acid concentration (700 to 1200 ppM as SiO2). The experimental technique involved analyses for molybdate-reactive silicic acid as a function of time after a supersaturated solution of Si(OH)4 was prepared by mixing aliquots of a stock silicate solution with buffered brine. The isothermal rate of SiO2 condensation is a strong function of supersaturation (C/Ce), pH, and salinity. The overall kinetics follow what is expected from the general theory of phase transitions. The kinetic results suggest that growth of nucleated particles is activation controlled, at least initially. The increase of condensation rate with salt content is attributed to a decrease in equilibrium solubility of SiO2. In effect, higher salt concentrations increase supersaturation and lead to faster nucleation. Higher nucleation and growth rates are observed at higher pH's. An increase of 1 pH unit increases rates by a factor of about 10. The pH dependence is consistent with the hypothesis that SiO(OH)3− is one of the reacting species. Temperature has little effect on condensation rate at a fixed initial silicic acid concentration. This result suggests that the increase in rate of activated steps brought about by increased temperature is essentially counterbalanced by a decrease in supersaturation (because of higher equilibrium solubility at higher temperatures). The kinetic results yield an activation energy of 17 kcal/mol for addition of silicic acid to a nucleated particle and 45 ergs/cm2 for the interfacial energy between precipitated silica and the brine. NaCl, KCl, CaCl2 and MgCl2 had no specific effect on condensation rate. However, NaF had a large effect on rate; a few ppM (15 to 100) of fluoride ion accelerate condensation substantially.
Download or read book A Study of Brine Treatment written by Sidney L. Phillips and published by . This book was released on 1977 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1994 with total page 806 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiannual, with semiannual and annual indexes. References to all scientific and technical literature coming from DOE, its laboratories, energy centers, and contractors. Includes all works deriving from DOE, other related government-sponsored information, and foreign nonnuclear information. Arranged under 39 categories, e.g., Biomedical sciences, basic studies; Biomedical sciences, applied studies; Health and safety; and Fusion energy. Entry gives bibliographical information and abstract. Corporate, author, subject, report number indexes.
Download or read book Kinetics of silica deposition from simulated geothermal brines written by E. G. Bohlmann and published by . This book was released on 1980 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Kinetics of Silica Deposition from Simulated Geothermal Brines written by and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Supersaturated brines were passed through columns packed with several forms of silica (crystalline .cap alpha. quartz, polycrystalline .cap alpha. quartz, and porous Vycor). Also, silica deposition on ThO2 microspheres and titanium powder was studied under controlled conditions of supersaturation, pH, temperature, and salinity. The residence time was varied by adjustments of flow rate and column length. The silica contents of the input and effluent solutions were determined colorimetrically by a molybdate method which does not include polymers without special pretreatment. Essentially identical deposition behavior was observed once the substrate was thoroughly coated with amorphous silica and the BET surface area of the coated particles was taken into account. The reaction rate is not diffusion limited in the columns. The silica deposition is a function of the monomeric Si(OH)4 concentration in the brine. The deposition on all surfaces examined was spontaneously nucleated. The dependence on the supersaturation concentration, hydroxide ion concentration, surface area, temperature and salinity were examined. Fluoride was shown to have no effect at pH 5.94 and low salinity. The empirical rate law which describes the data in 1 m NaCl in the pH range 5-7 and temperatures from 60 to 120°C is given.
Download or read book Dissolution and Condensation Kinetics of Crystalline and Amorphous Silica in Alkaline Solutions written by Shawn David Thornton and published by . This book was released on 1985 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Kinetic Equations and Type Curves for Predicting the Precipitation of Amorphous Silica from Geothermal Brines written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The kinetics of amorphous silica precipitation from aqueous solution up to 100°C and containing up to 1M NaCl were studied experimentally. Empirical equations for the rate of molecular deposition on surfaces as a function of temperature, dissolved silica concentration, pH and salinity are presented. Empirical type curves which depict the decrease in dissolved silica concentration through homogeneous nucleation of colloidal silica are also presented. Two practical examples related to geothermal practice are given.
Download or read book Geothermal Energy Update written by and published by . This book was released on 1976 with total page 668 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Kinetics of Silica water Reactions written by James Donald Rimstidt and published by . This book was released on 1981 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ERDA Energy Research Abstracts written by United States. Energy Research and Development Administration. Technical Information Center and published by . This book was released on 1977 with total page 1066 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Heterogeneous Kinetics of Silica Dissolution in Aqueous Media written by Gerald Sheldon Wirth and published by . This book was released on 1980 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chemistry of Silica in Cerro Prieto Brines written by Oleh Weres and published by . This book was released on 1980 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chemistry of Silica in Cerro Prieto Brines written by and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The precipitation of amorphous silica from synthetic geothermal brines which resemble the flashed brine at Cerro Prieto has been studied. It was found that part of the dissolved silica quickly polymerizes to form suspended colloidal silica. The colloidal silica flocculates and settles slowly at unmodified brine pH values near 7.35. Raising the pH of the brine to about 7.8 by adding base and stirring for a few minutes causes rapid and complete flocculation and settling. These results have been confirmed in the field using actual Cerro Prieto brine. Both in the laboratory and in the field quaternary amines were found to be effective with some brine compositions but not with others. Polyacrylamides do not work at all. These results suggest the following simple preinjection brine treatment process: age the brine for 10 to 20 minutes in a covered holding tank, add 20 to 30 ppM lime (CaO), stir for 5 minutes, and separate the flocculated silica from the brine using a conventional clarifier. The brine coming out of such a process will be almost completely free of suspended solids. The pilot plant tests needed to reduce this conceptual process to practice are discussed. The rate of deposition of silica scale from synthetic brines was separately studied. It was found that a modest decrease in pH could significantly reduce the scaling rate at a reasonable cost. The equilibrium chemistry of Cerro Prieto brine was studied theoretically. These calculations indicate that increasing the brine pH to remove silica might cause some precipitation of carbonate minerals, but also that this problem could easily be eliminated at a reasonable cost if it did arise.
Download or read book Mineral Scales and Deposits written by Zahid Amjad and published by Elsevier. This book was released on 2015-05-21 with total page 785 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mineral Scales and Deposits: Scientific and Technological Approaches presents, in an integrated way, the problem of scale deposits (precipitation/crystallization of sparingly-soluble salts) in aqueous systems, both industrial and biological. It covers several fundamental aspects, also offering an applications’ perspective, with the ultimate goal of helping the reader better understand the underlying mechanisms of scale formation, while also assisting the user/reader to solve scale-related challenges. It is ideal for scientists/experts working in academia, offering a number of crystal growth topics with an emphasis on mechanistic details, prediction modules, and inhibition/dispersion chemistry, amongst others. In addition, technologists, consultants, plant managers, engineers, and designers working in industry will find a field-friendly overview of scale-related challenges and technological options for their mitigation. Provides a unique, detailed focus on scale deposits, includes the basic science and mechanisms of scale formation Present a field-friendly overview of scale-related challenges and technological options for their mitigation Correlates chemical structure to performance Provides guidelines for easy assessment of a particular case, also including solutions Includes an extensive list of industrial case studies for reference
Download or read book Kinetic Equations and Type Curves for Predicting the Precipitation of Amorphous Silica from Geothermal Brines written by Oleh Weres and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Kinetics of Silica water Reactions written by James Donald Rimstidt and published by . This book was released on 1982 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt:
