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Adsorption time curves were determined for cotton fabric dyed with direct dyes under different conditions. A new simple method is described for kinetic analysis of adsorption time curves. Adsorption equilibria, specific rate constants, diffusion coef ficients, diffusion resistance, steady-state equilibrium constants, adsorbent capacities, finite bath exhaustions, activation energies, and reaction enthalpies were determined from the time curves. Specific rate constants and the diffusion coefficients correlated with the chemical structures of direct dyes (number of aromatic rings and ionizable sulfo groups).

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Dyeing of cotton fabrics treated with dimethyloldihydroxyethyleneurea and triethanolamine is discussed. Adsorption time curves from finite baths of untreated, mercerized, and crosslinked cotton print cloths have been studied. Mercerization did not change heterogeneous diffusion resistance but increased adsorption equilibrium constants, dyeing affinities, and diffusion coefficients. Maximum dyeing capacities of mercerized cotton were lower. Crosslinking reduced most of the kinetic constants (rate constants, structural diffusion resistance constants, maximum dyeing capacities, activation energies, and diffusion coefficients). Triethanolamine additive enhanced the kinetic constants and the dyeabilities of crosslinked cotton fabrics. The results indicated that in the crosslinked cotton, triethanolamine reacted preferably with the crosslinks and not with the remaining free reactive groups of cotton fabric.Crosslinking by dimethyloldihydroxyethyleneurea (DMDHEU) reduces the equilibria and dyeing rates of cotton or other cellulosic materials [7,9,10]. On the other hand, mercerization increases the dyeing rates. When the cotton fabrics are crosslinked and treated with triethanolamine (TEA), nitrogen content and dyeability increase [ 1 ] . In order to better understand the effect of crosslinking by DMDHEU and TEA on dyeing kinetics from finite baths, we have studied the time curves under different dyeing conditions using the following diffusion kinetic equation [2][3][4][5] :where a is the adsorption of the dye on cotton in time t, a~ is the equilibrium adsorption at t -oo , k is the specific rate constant, Co is the concentration of cotton in a finite bath, and n is the structural diffusion resistance constant. The half-life of dyeing is then From these constants, we have determined other kinetic constants (maximum adsorption capacities ~B, adsorption equilibrium constants Ko, diffusion coe~-cients D, activation energies AE*, enthalpies 011, and exhaustions a ) [ 2 ] . By means of these kinetic parameters, we can predict the structural changes of cotton fabrics and the dyeing kinetic profiles from finite baths under different conditions ( dye and cotton concentrations and temperatures).We determined the constants of Equation 1 using the computer mathematical regressions of the time curves [3]. Graphical determination [2] was less accurate but agreed well in the limits of errors with the computer analysis. The maximum adsorption capacities, the adsorption equilibrium constants, the acti-. vation energies of dyeing, and the apparent enthalpies were determined statistically from two or more time curves with two or more dye and cotton concentrations and two or more temperatures as described previously [ 2 ] . The apparent diffusion coefficients were calculated by comparing Equation 1 with the integrated Fwk's diffusion equations [2, 6, 12] under the assumption that cotton fibers are cylinders:All these kinetic constants obtained from the time curves were a useful tool for elucidating the dyeing mechanism and some structural ...

Peptide subunits of oryzenin preparation from postharvest and stored rice grains of the two typical U.S. rice varieties (long and medium grain) have been studied by SDS-PAGE. Both studied varieties of the postharvest and/or stored rice had similar qualitative peptide subunit compositions. The subunits which occurred in the reduced denatured oryzenin had molecular weights 12 300,14 200,22 000-23 000 (double spot), 32 000-37 000 (double spot),