Polyamide Fibers Covered with Chlorhexidine: Thermodynamic Aspects

摘要

Results of dynamic and equilibrium of sorption of a reactive dye Remazol Brilliant Blue, and a bactericidal agent, Digluconate of Chlorhexidine over Polyamide fibers are presented with the aim of supplying the fiber with bactericidal properties. However, adsorption of Chlorhexidine onto Polyamide is scarce due to the lack of interactions between the reactive groups of the fiber and the antiseptic molecule. Therefore, in order to provide the fiber surface with anionic groups, fiber has been previously dyed with Remazol Brilliant Blue which increases the negative charge of the fiber surface due to the presence of its sulfonate end groups. Thermodynamic parameters of equilibrium sorption in the two situations, fiber/dye and fiber-dye/Chlorhexidine, have been analyzed, as function of the temperature, pH and concentration of the dye in the pretreatment. Results show that when sorption of Remazol Brilliant Blue reaches the value of about 50 mmol/ kg at the higher temperature and concentration tested, the amount of Chlorhexidine adsorbed exhibits its maximum value which is 6 mmol/kg. Both processes, adsorption of Remazol Brilliant Blue and adsorption of Chlorhexidine, fit well to Langmuir adsorption model, suggesting the existence of some kinds of specific interactions between adsorbent and adsorbate. Thermodynamic functions show that the interaction is endothermic and spontaneous in all the rage of temperature tested. The kinetic studies show that sorption of Remazol Brilliant Blue is better described by pseudo-first order model, while sorption of Chlorhexidine fits better to pseudo-second order model, and seems to be quicker process. According to the obtained results, chemical interaction between the vinyl-sulfone group of Remazol Brilliant Blue and the amine groups of Polyamide fiber, followed by electrostatic interactions between the guanine group of the Chlorhexidine and the sulfonate group of the dye must be considered in order to explain the adsorption process.