SORPTION OF DIMETHYLDODECYLPHOSPHINE OXIDE BY COTTON,NYLON, RAYON, AND SELECTED PARTICULATE SUBSTRATES

The sorption of radioactive dimethyldodecylphosphine oxide (DC12PO) in various substrates has been studied as a function of both surfactant concentration, and of time. The substrates studied and the equilibrium sorption levels (in milligrams per gram of substrate) observed at room temperature were: Cotton, 2.1; rayon, 7.6; nylon 11.8; polyester, 0.26; carbon black, 8.4; lampblack, 16.9; polyethylene, 1.3; polystyrene, 375; and silica, 176. With cotton, the quantity of DC12PO sorbed increased with increasing temperature; with carbon black, no such change was observed. Sorption on the hydrophobic substrates generally occurred below the critical micelle concentration (cmc) attaining the maximum level near the cmc. With the hydrophilic substrates, most of the sorption occurred above the cmc. Monolayer coverage is indicated by the data obtained for carbon black, polyethylene, polystyrene, silica, and polyester fabric. The rate of sorption data obtained for cotton, rayon, and nylon fabrics can be treated as resulting from diffusion processes. Average diffusion coefficients are calculated to be about 5 × 10-12 cm2 per see for all fabrics at 27.6°C and resemble data published for the sorption of dyes. Sites for sorption on cotton appear to be heterogeneous, and rather high solubility of DC12PO occurs in rayon and nylon. The sorption properties for DC12PO are similar to those reported for alkylpolyoxyethyleneglycol monoethers. © 1969.