Efecto sobre tamaño y carga superficial de nanopartículas ferroeléctricas de titanato de bario modificadas con quitosano extraído de exoesqueleto de langostino
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Date
2023
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Universidad Nacional de Trujillo
Abstract
En la presente investigación se evaluó el efecto de la modificación superficial de las nanopartículas de titanato de bario con quitosano, sobre el tamaño y carga superficial. El quitosano fue obtenido a partir de la quitina extraída de exoesqueletos de langostino Penaeus vannamei, con óptimo grado de acetilización (%DA) de 5,1347%, siendo ligeramente reducido hasta 5,0178, 4,9733 y 3,7451%, al ser sometido a un proceso de hidrólisis con ácido sulfúrico al 1, 2 y 3% (v/v) respectivamente; incrementando la formación de grupos amino durante el proceso de desacetilización en la transformación de la quitina en quitosano. Previo a la modificación superficial, las nanopartículas de titanato de bario, adquiridas de Sigma-Aldrich, fueron sometidas a un tratamiento térmico de recocido a 900°C con el propósito de obtener una estructura tetragonal ferroeléctrica; luego, fueron hidroxiladas con peróxido de hidrógeno en su superficie. La modificación superficial se realizó mediante gelación iónica con tripolifosfato de sodio (STPP) a fin de obtener nanopartículas de quitosano. 0,1 g de nanopartículas de titanato de bario hidroxilados fueron agregadas en una solución de ácido acético al 0,5 % (v/v) a un pH de 4,7; luego, sobre esta solución, se dejó caer gota a gota de una solución de STPP a 0,4 mg/ml con un pH de 11. La mezcla resultante fue sometida a ultrasonido por 20 minutos a temperatura ambiente. Finalmente, se procedió a la separación del nanocompuesto BaTiO3/Quitosano por medio de centrifugación por un tiempo de 30 minutos, a 4ºC y 9000 rpm, cuyo precipitado fue secado en una estufa a 60°C durante 3 h. Los patrones de difracción de rayos X y los espectros FT-IR revelaron una efectiva modificación superficial sin afectar la estructura tetragonal de las nanopartículas de BaTiO3. La modificación superficial con quitosano no hidrolizado incrementó el diámetro promedio desde 60 nm (sin modificar) a un valor de 442,1 nm; siendo menor este diámetro promedio (220,4 nm) al ser modificado con quitosano hidrolizado al 3% (v/v). La carga superficial (potencial Z) de las nanopartículas de BaTiO3 disminuyó desde +29,1 mV (sin modificar) hasta +19,15 mV cuando fueron modificadas con quitosano no hidrolizado y a un valor de +11,57 mV, al ser modificadas con quitosano hidrolizado al 3% (v/v).
In the present investigation, the effect of surface modification of barium titanate nanoparticles with chitosan on size and surface charge was evaluated. Chitosan was obtained from chitin extracted from Penaeus vannamei shrimp exoskeletons, with an optimal degree of acetylation (%DA) of 5,1347%, being slightly reduced to 5,0178, 4,9733 and 3,7451%, when subjected to a hydrolysis process with sulfuric acid at 1, 2 and 3% (v/v) respectively, increasing the formation of amino groups during the deacetylation process in the transformation of chitin into chitosan. Prior to surface modification, the barium titanate nanoparticles, purchased from Sigma-Aldrich, were subjected to an annealing heat treatment at 900°C in order to obtain a ferroelectric tetragonal structure; then, were hydroxylated with hydrogen peroxide on their surface. The surface modification was performed by ionic gelation with sodium tripolyphosphate (STPP) in order to obtain chitosan nanoparticles. 0,1 g of hydroxylated barium titanate nanoparticles were added in a 0,5% (v/v) acetic acid solution at pH 4.7; then, 0,4 mg/mL STPP solution with pH 11 was dropped onto this solution. The resulting mixture was subjected to ultrasound for 20 minutes at room temperature. Finally, the BaTiO3/Chitosan nanocomposite was separated by centrifugation during 30 minutes, at 4ºC and 9000 rpm, whose supernatant was dried in an oven at 60°C for 3 h. X-ray diffraction patterns and FT-IR spectra revealed effective surface modification without affecting the tetragonal structure of BaTiO3 nanoparticles. The surface modification with non-hydrolyzed chitosan increased the average diameter from 60 nm (unmodified) to a value of 442,1 nm; this average diameter being smaller (220,4 nm) when modified with hydrolyzed chitosan at 3% (v/v). The surface charge (Z potential) of the BaTiO3 nanoparticles decreased from +29,1 mV (unmodified) to +19,15 mV when modified with non-hydrolyzed chitosan and to a value of +11,57 mV when modified with 3% hydrolyzed chitosan (v/v).
In the present investigation, the effect of surface modification of barium titanate nanoparticles with chitosan on size and surface charge was evaluated. Chitosan was obtained from chitin extracted from Penaeus vannamei shrimp exoskeletons, with an optimal degree of acetylation (%DA) of 5,1347%, being slightly reduced to 5,0178, 4,9733 and 3,7451%, when subjected to a hydrolysis process with sulfuric acid at 1, 2 and 3% (v/v) respectively, increasing the formation of amino groups during the deacetylation process in the transformation of chitin into chitosan. Prior to surface modification, the barium titanate nanoparticles, purchased from Sigma-Aldrich, were subjected to an annealing heat treatment at 900°C in order to obtain a ferroelectric tetragonal structure; then, were hydroxylated with hydrogen peroxide on their surface. The surface modification was performed by ionic gelation with sodium tripolyphosphate (STPP) in order to obtain chitosan nanoparticles. 0,1 g of hydroxylated barium titanate nanoparticles were added in a 0,5% (v/v) acetic acid solution at pH 4.7; then, 0,4 mg/mL STPP solution with pH 11 was dropped onto this solution. The resulting mixture was subjected to ultrasound for 20 minutes at room temperature. Finally, the BaTiO3/Chitosan nanocomposite was separated by centrifugation during 30 minutes, at 4ºC and 9000 rpm, whose supernatant was dried in an oven at 60°C for 3 h. X-ray diffraction patterns and FT-IR spectra revealed effective surface modification without affecting the tetragonal structure of BaTiO3 nanoparticles. The surface modification with non-hydrolyzed chitosan increased the average diameter from 60 nm (unmodified) to a value of 442,1 nm; this average diameter being smaller (220,4 nm) when modified with hydrolyzed chitosan at 3% (v/v). The surface charge (Z potential) of the BaTiO3 nanoparticles decreased from +29,1 mV (unmodified) to +19,15 mV when modified with non-hydrolyzed chitosan and to a value of +11,57 mV when modified with 3% hydrolyzed chitosan (v/v).
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Keywords
Titanato de bario, Quitosano, Potencial zeta, Nanopartículas, Ferroelectricidad