Multimodal sorption of nonionic dyes with two amino groups by various polymers from water

Abstract

Sorption isotherms of nonionic dyes with two amino groups (one anthraquinone dye and two azo dyes) on various polymers from water were measured at 40–90°C (Nylon‐6 and cellulose film) and at 95°C (polyester microfiber). The isotherms were curved, convex to upward, in the range of low dye concentration Cs in water and almost linear in the range of medium to saturated Cs. The isotherms measured at low temperature (40°C for cellulose, 40–60°C for Nylon‐6, and at 95°C for polyester) were satisfactorily described by considering three concurrent modes of sorption. They are Nernst type partitioning and bimodal Langmuir sorption (sorption by the higher affinity sites with a small saturation value and that by the lower affinity sites with a large saturation value). However, for the sorption of the anthraquinone dye and one azo dye by Nylon‐6 film at high temperature (80–90°C), the amount of dye sorbed by the high affinity site decreased to negligibly small. Accordingly, the isotherms were expressed well by simple dual‐sorption model. © 1995 John Wiley & Sons, Inc.

Diffusion of Disperse Dyes on Nylon 6

“…Recently, we have found that when some nonionic dyes are sorbed by various polymers (including nylon 6 film) from water at low temperatures (40-.60*C), three kinds of sorption mode operate concurrently, i.e., n = 3 in Equation 1 [ 18]. For this case, the sorption isotherms are accurately expressed by Equation 6, which is Nemst-type partitioning plus two classes of Langmuir sorption, one with very high affinity (&,) and low saturation value (S, ) and the other with low affinity (KL2) and high saturation value (S2): ' When dye sorption follows Equation 6, the dye penetrates the polymer as three distinct species, i.e., dye taken up by partitioning (P species), by the first class of Langmuir sorption (LI species), and by the second class of the Langmuir sorption (L2 species).…”

“…Because of the high affinity and low saturation value of L j species on the polymer, this species predominates in polymers at very low Cf; the L, species is most strongly sorbed or immobilized in the polymer, and it has very low diffusivity. However, the first class of Langmuir sorption becomes negligible as the temperature rises, e.g., 80-90°C [ 18]. Consequently, the sorption and diffusion behaviors of the dye follow Equations 2 and 3, respectively.…”

“…Recently, however, we have measured the sorption isotherms of many purified disperse dyes and their model compounds on various polymers from water in the absence of dispersants, and we found that the isotherms of most disperse dyes are curved, convex upward, in the range of low dye concentrations in water [6,13,15,[17][18][19]. These isotherms are described well in terms of the multi-modal sorption model expressed by Equation 1 [ 18]:…”

“…These isotherms are described well in terms of the multi-modal sorption model expressed by Equation 1 [ 18]:…”

A novel utilisation of principal component analysis to optimise sorption isotherms and determine diffusion coefficients of five naphthalimide disperse dyes on polyester fibres

“…Major assumptions for simplifying the calculation of diffusion coefficients are: Constant surface concentration Uniform initial concentration throughout the fibre f ( r ) = C 1 , where, C 0 and C 1 denote fibre dye concentration at time t = t 0 and t = t 1 , and r is the radius vector. Equation can be approximated to the Taylor series, by the Shibusava or the Pade approximation methods . However, in the present paper a novel ‘To To’ simple numerical method was used to solve the polynomial equations of degree n, (where a is any real number).…”