Adsorption of Methylene Blue and Tetracycline by Zeolites Immobilized on a PBAT Electrospun Membrane

The detection of emerging contaminants in bodies of water has steadily increased in recent years, becoming a severe problem threatening human and ecosystem health. Developing new materials with adsorption properties to remove these pollutants represents an important step toward a potential solution. In this paper, a polybutylene adipate terephthalate (PBAT) nanofibrous membrane incorporating clinoptilolite zeolite was developed and its excellent performance in removing tetracycline (TC) and methylene blue (MB) from water was demonstrated. The composite membrane was prepared in two steps: firstly, a homogeneous dispersion of clinoptilolite (1 wt% respect to polymer) in a PBAT solution (12.6 wt%) was electrospun; secondly, the electrospun membrane was subjected to an acid treatment that improved its wettability through the protonation of the surface silanol groups of clinoptilolite. The resulting membrane was hydrophilic and showed higher adsorption for TC (800 mg/g) and MB (100 mg/g), using a low dose (90 mg/L) powdered zeolite. The maximum removal capacity was obtained at neutral pH, being the cation exchange reaction the main adsorption mechanism. Pseudo-second-order kinetics and Henry’s law agree well with the proposed chemisorption and the high affinity of TC and MB for the adsorbent. The material can be reused after the removal process without generating additional contamination, although losing some effectivity.Fil: Picon Borregales, David Emmanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física. Laboratorio de Polímeros y Materiales Compuestos; ArgentinaFil: Vergara Rubio, María Alicia. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e Ingeniería Ambiental; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física. Laboratorio de Polímeros y Materiales Compuestos; ArgentinaFil: Estevez Areco, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. Sede Olavarría del Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aire. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. Sede Olavarría del Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Física de Materiales; ArgentinaFil: Cerveny, Silvina. Consejo Superior de Investigaciones Científicas; España. Universidad del País Vasco; EspañaFil: Goyanes, Silvia Nair. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Centro de Física de Materiales; España. Donostia International Physics Center; Españ

PVA Nanofibers as an Insoluble pH Sensor

[EN] Turmeric has been widely studied as a color indicator for pH variations due to its halochromic properties. It has been tested in solution or included in some polymeric matrices. Some studies have demonstrated that its change in color is due to the tautomeric species of curcumin, and this property can be observed even if turmeric is assimilated in a film or nanofiber. Chitosan/polyethylene oxide (PEO) polymers have been tested in previous studies. Polyvinyl alcohol (PVA) nanofibers are used as potential carriers of drugs once they are insolubilized. The aim of this work is to cross-link PVA with citric acid (CA) to insolubilize the nanofibers and determine the effect on turmeric¿s halochromic properties. The nanofibers were treated with a sodium hydroxide (NaOH) solution, and a chromatic study was undertaken to determine color change. The change in color was assessed by eye (subjective) and by spectroscopy (objective). The nanofibers were characterized, in addition to the colorimetric study, by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) as well. The results demonstrate how thermal treatment induces cross-linking between the nanofibers, allowing them to keep their shape once the NaOH solution is applied to them. The opposite effect (solubilization) can be observed for non-cross-linked (NCL) samples. Although the final color varied, the cross-linked (CL) nanofibers¿ halochromic behavior was maintained. It was demonstrated that during cross-linking, ester groups are formed from the free carboxyl group in the cross-linked CA and the ketones present in the curcumin under acid conditions. So, CA acts as an acid catalyst to bond turmeric to the cross-linked PVA nanofibers.This research was funded by INSTITUTO VALENCIANO DE COMPETITIVIDAD EMPRESARIAL (IVACE), through the nominative line assigned to the Universitat Politècnica de València, approved by the Generalitat Valenciana Budget Act 2023.Mínguez-García, D.; Montava-Seguí, I.; Bonet-Aracil, M.; Gisbert Paya, J.; Díaz-García, P. (2023). PVA Nanofibers as an Insoluble pH Sensor. Polymers. 15(23). https://doi.org/10.3390/polym15234480152