Demineralization method

Two sets of samples were analyzed powders and carbon electrodes. Details about the synthesis of the carbonaceous materials have been published elsewhere. In brief, the samples were prepared using pillared clays as templates. Different carbon precursors were loaded into the layered pillared clay and pyrolyzed at 700°C for 4 hours. The structure of the clay remains intact at this temperature as evidenced by X-ray powder diffraction. The clay was then removed by conventional demineralization methods and the resultant carbon was oven-dried at 120°C overnight. 

Bone protein was extracted following the method described by Sealy (1986). Bone chips were demineralized in a weak HCl solution, then soaked in 0.1 M NaOH to remove base-soluble humic substances. Remaining material, which is mainly collagen, but includes non-collagenous proteins, was... 

Dissolved titanium method. Hydrothermal synthesis using tetrapropylammonium peroxytitanate (prepared from TEOT, distilled water, 30% aqueous H2O2, and 25% aqueous TPAOH) as the source of Ti and colloidal silica (Ludox AS-40) as the source of Si and TPAOH as template. All additions done at 278 K Preparation using TiCl2, 14% aqueous TPAOH, 30% colloidal silica, and demineralized water Preparation at low pH using fluoride ions as mineralizing agent... 

In the Murphy and Riley [85] method 10ml of demineralized water and 2ml of concentrated nitric acid were added to 0.15-0.2g of dry sediment (predried at 103°C) or plant material in a 100ml Erlenmeyer Flask. After a preliminary oxidation by evaporation of water and nitric acid on a hot plate, 2ml of concentrated perchloric acid were added, and the sample was boiled until clear. After cooling, the sample was diluted to 100 ml and an aliquot was withdrawn for orthophosphate determination by the ascorbic acid reduction method of Murphy and Riley [85]. Blanks and standards were treated as samples. 

Recently, Yekkala et al. [144,145] have proposed an HPLC method with fluorescence detection. The method involves a rather laborious sample preparation due to the peculiar nature of the substrate involved (teeth), including pulverization, demineralization, hydrolysis of dentin and derivati-zation with o-phthaldialdehyde and A-acetyl-L-cysteine in order to obtain the enantioseparation of aspartic acid. Using a similar procedure, Benesova et al. [146] found that, in comparison with GC, HPLC provides shorter analysis time and higher sensitivity. 

In general, most procedures are like the ones described above. For the modified method, an alternative DMB reagent is used and ten parts of this reagent are added to one part of Tris buffer to yield a reagent with a pH of 8.7-8.8. The reagent - Tris mixture is not stable and has to be prepared just prior to analysis. First, 20 pi of urine (sample) or water (blank) is added to the cuvettes or microtiter plates. The volume of standards, samples, and blanks are adjusted to 50 pi with demineralized water. Then, 275 pi of DMB-Tris reagent is added to each cuvette/well. Either all samples... 

The assay is carried out according to the method published by van Diggelen et al. [65]. Patient samples have to be dialyzed before the assay can be run. For that purpose, leukocyte homogenates (0.5-1 mg protein) are sonicated in 100 pi demineralized water. The tubes are centrifuged at 10,000 xgfor 10 min (4°C) and the supernatant is dialyzed against the dialysis buffer for 17 h at 4°C. 

DEMINERALIZATION. Removal from water of mineral contaminants, usually present in ionized form. The methods used include ion-exchange techniques, Hash distillation, or electrodialysis. Acid mine wastes may be purified in this way, thus alleviating the pollution problem. 

Sea water demineralization research has largely been of a developmental nature. Processes already known to be workable, if not economical, have been chosen, then debugged or in some cases radically modified in order to adapt them to the peculiarities of the desalinization problem. In contrast to this approach, the work reported here has been an endeavor to explore unknown areas, and to investigate the mere scientific possibility of various methods. 

Growing scarcity of fresh water in many places in this country and the rest of the world has stimulated the development of several potentially useful processes for saline water demineralization. Because fresh water is such a cheap commodity, these processes must demonstrate the maximum conceivable economy to compete with even the most expensive natural fresh water sources. Nearly all of these methods require considerable energy, either as heat or as electric power. Since this is a large cost item in these processes, solar distillation offers substantial operating economies, but at the expense of large investment requirement. 

The objective of any sea water conversion process is twofold to produce a demineralized water whose quality is adequate for the proposed use, and to produce this water at as low a cost as possible. In considering any new conversion process, after the establishing of the scientific and technologic soundness of the method, the question to be answered is the probable relative economics of the proposed process as compared to other processes, either actual (preferable) or proposed. One method of making this comparison is to prepare cost estimates. However, in some cases, such as this one, other indexes can be used. 

The semipermeable membrane proposed for the demineralization of sea water is based on H. L. Calendar s theory that osmosis takes place through the membrane as vapor, condensing at the opposite membrane surface. The actual membrane being used consists of two sheets of untreated cellophane separated by a water-repellent powder, such as a silicone-coated pumice powder. The vapor gap is maintained by an air pressure in excess of the pressure on the sea water and the cellophane sheets support the capillary surfaces, which will withstand pressures up to 1500 p.s.i. A number of successful experiments are reported with over 95% desalinization. The present effort is directed toward obtaining reproducible experimental results and better methods of fabricating the vapor gap. 

The proposed electrochemical method of saline water demineralization is similar to electrodialysis, in that ions are removed from a solution by electrical transference. If the electrodes are porous, oppositely charged ions will be attracted to them and thus... 

A program of chemical characterization of factors has begun, aimed at improvement of the demineralization capacity. Ion-responsive functional groups have been built into carbon electrodes. Further improvement of electrodes will determine whether an eventual application of this method will be economically important. 

A peculiar method of desalting water is the osmionic demineralization developed by G. W. Murphy (702,103). In a multicell are circulated side by side a very concentrated salt solution, a moderately concentrated salt solution and a dilute salt solution to be desalted. The arrangement is now such that only Na+ and Cl- ions can move from the brine to the moderately concentrated salt solution, when simultaneously also Na+ and Cl- ions can move from the dilute salt solution to this moderately concentrated solution. In this manner the dilute solution is desalted. 

To examine the clinical utility of our method, we have conducted various preliminary studies in which we have shown using artificial caries models of demineralization and remineralization that the P959 depolarization ratio of PRS measurements enables us to not only follow the progression and ex-tent/severity of early caries development, but also to monitor the repair process involving fluoride treatment [49, 50]. In addition, other initial studies have... 

In light of the fact that coal ash is measured by removal (combustion) of the organic part of the coal, there are methods for measuring the mineral matter content of coal. Such a method involves demineralization of the coal that depends on the loss of weight of a sample when it is treated with aqueous hydrofluoric acid at 55 to 60°C (130 to 140°F) (Radmacher and Mohrhauer, 1955 Given and Yarzab, 1978 ISO 602). However, pyrite is not dissolved by this treatment and must be determined separately. Other methods include the use of physical techniques such as scanning electron microscopy and x-ray diffraction (Russell and Rimmer, 1979). 

A reliable method of measuring the mineral matter content of a coal is an acid demineralization procedure. The method depends on the loss of weight of a sample when treated with 40% hydrofluoric acid at 50 to 60°C (122 to 140°F). Treatment of the sample with hydrochloric acid before and after treatment with hydrofluoric acid helps prevent the retention of insoluble calcium fluoride (CaF2) in the coal. Pyrite is not dissolved in the treatment, consequently, pyrite and a small amount of retained chloride must be determined separately. Since two-thirds of the mass of the pyrite (FeS2) is accounted for by the presence of ferric oxide (Fe203) in the residual ash, the mineral matter content is then given by the formula... 

Determination of a good value for the percent of mineral matter content (% MM) is a very important component of coal analysis. If this quantity cannot be determined directly by the acid demineralization or low-temperature ashing procedure discussed previously, or by other suitable methods, it is possible to calculate a reasonable value for the mineral matter in coal, provided that the necessary data are available. 

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