Solubility threshold

Sulfur Polymer Cement. SPC has been proven effective in reducing leach rates of reactive heavy metals to the extent that some wastes can be managed solely as low level waste (LLW). When SPC is combined with mercury and lead oxides (both toxic metals), it interacts chemically to form mercury sulfide, HgS, and lead sulfide, PbS, both of which are insoluble in water. A dried sulfur residue from petroleum refining that contained 600-ppm vanadium (a carcinogen) was chemically modified using dicyclopentadiene and oligomer of cyclopentadiene and used to make SC (58). This material was examined by the California Department of Health Services (Cal EPA) and the leachable level of vanadium had been reduced to 8.3 ppm, well below the soluble threshold limit concentration of 24 ppm (59). 

Where silicate levels are high (say, close to or above 150 ppm as Si02), the caustic alkalinity level must be at least 2.5 times the silica. At this level of alkalinity, any magnesium present will precipitate as a magnesium hydroxide sludge. Maintaining a high pH level also raises the solubility threshold level of silica. 

Disintegration official in Brit Pharmacon and USP PMA Tablet Committee proposes 1% solubility threshold USP and NF Joint Panel on Physiological Availability chooses dissolution as a test chooses an apparatus Initial 12 monograph standards official Variables assessment more laboratories, three Collaborative Studies by PMA and Acad. Pharm. Sci First calibrator tablets pressed First Case default proposed to USP... 

In this application bimodal pressure-sensitive adhesives consisting of C i C i x polymethacrylates were prepared that exhibited high adhesion to low solubility threshold (LSE) substrates at ambient temperature and at elevated temperature. These materials were free radically prepared in a two-stage single-step polymerization process. 

In California Code of Regulations (CCR) Title 22, the State of California imposes additional requirements for the disposal of waste containing 20 inorganic and 18 organic persistent and bioaccumulative toxic substances (CCR, 1991). Hazardous characteristics of waste streams contaminated with these substances are determined as Total Threshold Limit Concentrations (TTLQ and Soluble Threshold Limit Concentrations (STLC), shown in Appendix 4. 

List of California Toxic Substances, their Soluble Threshold Limit Concentrations and Total Threshold Limit Concentrations... 

STLC denotes Soluble Threshold Limit Concentration. 

Ascorbate may also increase the urinary excretion of uric acid, and be possibly protective against the development of gout, but may raise the urinary concentration above the low solubility threshold, thus increasing the likelihood of developing urate renal stones. 

Table 2. Solubility thresholds of carotenoids in the membranes formed with different lipids...

Liprd Carotenoid Temperature m Solubility threshold [mol%] Reference... 

Due to clogging of fine filters (e.g., 0.45 /rm is commonly regarded as the soluble threshold), it is often difficult in a realistic time frame to collect a volume of suspended matter sufficient for many chemical analyses of contaminants. The use of high flow commercial centrifugal separators (e.g., Westfalia and Alfa Laval ) can overcome this problem. ... 

Cal 1forni a Soluble threshold limit concentration for wastes 0.25 mg/L CELDS 1992... 

The anodic partial reaction also involves a charge transfer at the interface because a metal atom loses electrons. It then dissolves in the solution as a hydrated or complexed ion and diffuses towards the bulk. In the vicinity of the metal surface, the concentration generated by dissolution therefore often exceeds that of the bulk electrolyte. Once the solubility threshold is reached, solid reaction products begin to precipitate and form a porous film. Alternatively, under certain conditions, metal ions do not dissolve at all but form a thin compact oxide layer, called passive film. The properties of the passive film then determine the rate of corrosion of the underlying metal (Chapter 6). 

Based on the research work that has been carried out on the interaction of polyelectrolytes and ionic surfactants, the CAC may be looked upon as a solubility parameter. CAC is the solubility threshold when the two components (polymer and surfactant) are mixed. At the CAC, the solution starts becoming turbid and the surfactant-polymer complex begins to precipitate. This process takes place in all the systems containing ionic polymer and an oppositely charged smfactant and is called colloid titration (Goddard and Ananthapadmanabhan 1993 La Mesa 2005). In colloid titration, the CAC can be expressed as ... 

Brun and Alden clearly summarized the interplay of critical eluent composition >cr and the solubility threshold >goi of a polymer in GELC [24]. If the eluent composition at the time of injection results in precipitation of the polymer, dissolution occurs if the eluent composition exceeds the solubility threshold 4>soi. However, dissolution of the pol5Tner is a necessary but not a sufficient requirement to elute the polymer from the column. If dissolution occurs at an eluent composition the polymer molecules become dissolved but... 

Most chemical compounds, dissolved in most solvents, show the so-called direct solubility that is, the solubility threshold increases with temperature. 

Another option is to obtain, at an approximately constant temperature, the precipitation of the crystals by increasing the solute concentration above the solubility threshold. To obtain this, the solute/solvent mass ratio is increased using the technique of evaporation. This process is of course insensitive to change in temperature (as long as hydration state remains unchanged). 

NOTE Reported are average DSE values ( Av DSE ) for the top 10 descriptors that were found to be most responsive to differences between soluble and insoluble compounds. DSE values were averaged over all five solubility threshold ranges. 

G. Total Threshold Leaching Concentration (TTLC) and Soluble Threshold Limit Concentration (STLC)... 

---