メチルオレンジおよびその同族体のセロハンへの吸着に対する染料会合の影響

抄録

Cellophane was dyed with methyl orange (MO), ethyl orange (EO), and butyl orange (BO) in the presence and absence of sodium chloride. The resultant adsorption behaviors of MO and its homologs on the cellophane were interpreted on the basis of a mean activity coefficient and an aggregation number of the dye which were reported in previous pubulications. In the absence of NaCl the amounts of the dyes taken up by cellophane at 50°C were in the order MO>EO>BO. According to the previous reports, the dye aggregates in aqueous solution and the aggregation number increases with an increase in the carbon number of alkyl groups in the dye molecule. Consequently, with increasing aggregation number the repulsion forces between the negatively charged cellophane and dye increased and the diffusivity of the dye into cellophane was slowed down. Thus the amount of the dye taken up by cellophane decreased. The chemical potential of the dye in aqueous solution obtained from the previously reported activity also suggested that the tendency of the dye to transfer from the solution to the matrix lowered with increasing carbon number of the alkyl groups. Dye disaggregation caused by raising temperature of the solution resulted in the increase in the adsorption of BO at higher temperatures. The dye adsorption in the presence of 0.03M NaCl can be also explained on the basis of dye aggregation.