Dissolution—precipitation option

The dissolution/precipitation option in SOLMINEQ.88 can be used to carry out ... 

Major new options in SOLMINEQ.88 include a boiling option, volatile fractionation between oil, gas and water, an adsorption and ion exchange option and a dissolution/precipitation option. Interactive programs have been written which facilitate input, running and examination of the output. 

Some of the limits mentioned above can be relaxed by carefully using various SOLMINEQ.88 options. For example, if the formation temperature is not known, the calculated value from one of the chemical geothermometers can be used (21). If an element has not been analysed for, an approximate value can be obtained by assuming equilibrium with the appropriate formation mineral using the mineral dissolution and precipitation option. If carbon dioxide was known to have been lost between the time of sampling and analysis but the pH was measured in the lab and at the time of sampling, the amount of carbon dioxide in the water at the time of sampling can be recalculated. Other techniques and options in SOLMINEQ.88 can be used, but each assumption of this type should reduce confidence in the results. 

Other options for the purification of CA include dissolution in hot water, aqueous ammonia, aqueous formaldehyde, or hot dimethylformamide followed by filtration to remove most of the impurities. The CA is recoverable by cooling the aqueous solution (84), acidifying the ammonium hydroxide solution (85), or cooling the dimethylform amide solution with further precipitation of CA by addition of carbon tetrachloride (86). Sodium hydroxide addition precipitates monosodium cyanurate from the formaldehyde solution (87). 

If you want to keep the option of dissolution or precipitation open, define the mineral phases twice, once using dis (dissolve), and a second time using pre (precipitate). 

The smart response capability of polysaccharides upon application of stress allows polar and apolar domains to easily form or disintegrate due to variation of the order/disorder ratio at the molecular level. This finally results in variation of specific crystallinity index or crystalline/amorphous ratio at the macroscopic level. Significant variation of interactive properties may even be achieved by minor variation of branching characteristics, which changes surface/volume ratio and, hence, preferences for inter- or intramolecular stabilization. Additionally, a rather effective response option is variation of relative percentages of molar and mass fractions by limited degradation/ reorganization or precipitation/dissolution transition. 

Fig 7 2 FI on-line filtration systems without precipitate dissolution, a, normal FIA (nFlA) mode with sample injected into precipitant b, nFlA mode with sample injected into water carrier before merging with precipitant and c, reversed FIA (rFlA) mode with precipitant injected into sample or blank. S, sample PR, precipitant P, pump F, filter, D, detector, W, waste R, reagent (optional) BLK, blank [13,16]. 

Fig.7J Schematic diagram of a FI on-line precipitation-dissolution system used for the indirect AAS deteimination of chloride and iodide. PI, P2, pumps S, sample injector valve VI, V2, valves F, filter PR, precipitant (Ag ") WA, washing solution (HNO3) DS, dissolution solvent (6M NH4OH) R, water diluent (optional) D, detector, and W, waste [29].

Fig.7 Schematic diagram of a FI filterless on-line precipitation system with precipitate dissolution using a knoned reactor (KR) as precipitate collector, a. sample loading (precipitate collection) sequence b, precipitate dissolution sequence. Pi. P2. peristaltic pumps V. 4 5 channel injector valve PR. precipitant S. sample R. buffer reagent (optional) DS, dissolution solvent KR, knoned reactor precipitate collector and W, waste [21].

As Fig. 9.10 shows, the microcentrifuge test is also used (1) to quantify precipitation inhibition for compounds that rapidly crystallize and (2) to compare dissolution rates for SDDs of more lipophilic compounds, which tend to dissolve more slowly as particle size increases during process scale-up. A simulated gastric exposure step before dissolution in simulated intestinal media can also be added. This option is useful when evaluating weakly basic compounds that have pH-dependent solubility (Mathias et al. 2013). 

Electrocoagulation process with bipolar alumimmi electrodes has been used for defluoridation. The influence of parameters such as interelectrode distance, fluoride concentration, temperature and pH of the solution were investigated and optimized with synthetic water in batch mode. A technology for defluoridation through electrochemical route was developed. The process involves adsorption of fluoride with freshly precipitated aluminum hydroxide, which is generated by the anodic dissolution of aluminum or its alloys in an electrochemical cell. The above technology is power intensive inhibiting its application in remote rural environment use of solar power is an option. 

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