Alginate-based membranes embedding zinc oxide nanoparticles are prepared via electrospinning and exploited as biosorbent materials. The mats exhibit a uniform texture characterized by the presence of nanofibers with an average diameter of 100 nm and interconnected voids of 140 nm average size. UV-vis spectrophotometric tests were performed to evaluate the membrane uptake/release performances by employing aqueous solutions of Methylene Blue (MB) and Congo Red (CR), chosen as model probes of basic and acidic type, respectively. Isotherm kinetics and equilibrium data are fitted with theoretical models to acquire information on the process mechanisms and rates. At low dosage, the mats show comparable adsorption capacity toward both dyes with limited selectivity for the cationic one suggesting that the process is conditioned by the macroporous structure of the membranes. Moreover, a good reusability for achieved for MB after simple washing steps in deionized water. Remarkably, the desorption efficacy under physiological-like conditions turn out to be very high for MB but reduced for CR indicating that the release process is affected by ionic interactions. Based on the results, the electrospun membranes reveal potential as innovative, low-cost, and versatile absorbent platforms to be used in drug delivery applications as well as in purification processes.
Keywords: Dye adsorption-release; Electrospun membranes; Sodium alginate.
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