Turbidity purification process

The caprolactam obtained must meet die specifications of permanganate number, volatile bases, hazen color, UV transmittance, solidification point, and turbidity in order to be used for repolymerization alone or in combination witii virgin CL.5 Reported CL purification methods include recrystallization, solvent extraction, and fractional distillation. One solvent extraction technique involves membrane solvent extraction. Ion exchange resins have been shown to be effective in the purification of aqueous caprolactam solutions. In one such process,... 

Municipal or other public water systems typically have contaminants of two types those that pass through the municipal purification system and those that are residues from the treatment process itself. Bacteria and turbidity are examples of the former. The latter may include materials such as alkalinity, alum, buffers, bromate, chlorine, chlorite, copper, haloacetic acids and trihalomethanes. 

Ammonium sulfate precipitation can be achieved by two approaches the addition of solid ammonium sulfate salt or by adding saturated ammonium sulfate solution. The addition of solid ammonium sulfate to the sample is not recommended for most applications because it results in localized high salt concentrations in the sample that might precipitate more contaminants. The addition of saturated ammonium sulfate solution (100% solution) (see Note 2) is highly recommended since the solution is quickly mixed with the sample. Precipitate formation is a time dependent process and can be tracked by measuring the turbidity of the solution. Complete precipitation occurs between 3 and 8 h at 4° C. The precipitate once formed, is collected by centrifugation and solubilized in an appropriate volume of buffer and stored at -80° C or dialyzed in the buffer of choice for further purification. 

A process to prepare carbon-modified Ti02, also active under visible-light irradiation, was developed heating of Ti02 powder either in a flow of carbon-containing gas (e.g., -hexane or ethanol) at 400 to 500°C or in ethanol vapor at 120°C in an antoclave). A portion of deposited carbon is thought to substitute oxygen in the anatase lattice on the particle surface. A small extent of carbon deposition, about 0.5 mass%, was found to result in only a small decrease in photoactivity, but was sufficient to make turbidity low and, as a consequence, practical water purification efficiency was markedly improved. 

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