Studies on the Sorption of Azo Dyes Containing Fluorine Atoms by a Nylon 6 Film. Part 1. Effects of fluorine atoms on the sorption of azo dyes by a nylon 6 film.

Abstract

The sorption behavior of sodium 1-phenyl-2-hydroxy-6-naphthalenesulfonate and its deriva tives by a nylon 6 film was investigated in order to elucidate the effects of fluorine atoms. For the deriva tives, the amount of dye sorbed increased with time, and equilibrium sorption was not established even af ter the film was soaked in the aqueous dye solution for 7 days. The sorption isotherms obtained were in terpreted by considering the dual sorption mechanism which is composed of partition and Langmuir type sorption. The partition coefficients were dependent on the sorption time, while the parameters for Lang muir type sorption were independent. The thermodynamic parameters calculated from the temperature de pendence of the intrinsic binding constants for Langmuir type sorption were greatly influenced by the in troduction of a trifluoromethyl and methyl group into the dye molecule. This result is discussed in consid eration of hydrating water molecules around the dye anions.

Sorption of Fluorinated Azo Dyes Containing Two Sulfonate Groups by a Nylon 6 Film.

“…This suggests that the substituents other than the sulfonate group also influence the time dependence of the dye sorption. As was pointed out in our previous papers [3,4], Langmuir type sorption is independent of sorption time, while partition is strongly dependent. Therefore, the difference of the time dependence in the substituents is probably due to the discrepancy of the effects on the partition type sorption.…”

“…The amino end group content was determined as 3.53 X 10-5 equivalent per g of nylon by the titration of a m-cresol/methanol solution of the nylon 6 with an aqueous methanol solution of hydrochloric acid. This accurate titration showed that the amino end group content (4.65 X 10-5 eq g-1) described in the previous papers [3,4] was not correct. The nylon 6 film was pretreated in boiling water for 90 min, immersed in distilled water for 1 day, soaked in aqueous hydrochloric acid of pH3 for 1 day, and dried in a desiccator with silica gel.…”

“…The amounts of dye sorbed for the dyes containing two sulfonate groups were reduced to one-half that for the dyes having one sulfonate, whose reason will be discussed in the later section. The sorption isotherms were analyzed by means of the following bimodal sorption equation [1,3,4]: (1) type sorption term may contain an activity effect on the free dye in the higher concentration region. TheKP, n, and KL values were determined in the same manner as described in our previous paper [3] and are given in Tables 2, 3, and 4, respectively.…”

“…The sorption isotherms were analyzed by means of the following bimodal sorption equation [1,3,4]: (1) type sorption term may contain an activity effect on the free dye in the higher concentration region. TheKP, n, and KL values were determined in the same manner as described in our previous paper [3] and are given in Tables 2, 3, and 4, respectively. The experimental data were exactly fitted by a curve drawn using the sorption parameters thus obtained (Fig.…”

“…We have investigated the effects of fluorine atoms on the sorption of acid dyes containing a trifluoromethyl group by a nylon 6 film [2][3][4] and a silk fiber [5]. As a result, the introduction of the fluorine atoms made enthalpy change and entropy change for the Langmuir type sorption more exothermic and less entropic, respectively, in the case of the nylon 6 film.…”