Effect of the sol-gel route on the textural characteristics of silica imprinted with Rhodamine B.
A series of silica xerogels that support Rhodamine B as a template were synthesized using distinct sol-gel routes, namely, acid-catalyzed routes, a base-catalyzed route, acid-catalyzed with base-catalyzed (two steps) hydrolytic routes, and a FeCl3 -catalyzed nonhydrolytic route. The extraction methods (thermal, Soxhlet, water washing, and ultrasound) were also evaluated. The resulting xerogels were characterized through porosimetry using nitrogen adsorption/desorption. The samples were further analyzed through small-angle X-ray scattering, Fourier transform infrared spectroscopy, and SEM. The preparation route affected the materials' textural properties. Extraction was optimized using acid and two-step routes. The acid route from Rhodamine B to Rhodamine 6G generated the highest selectivity factor (2.5). The nonhydrolytic route produced the best imprinting factor. Competitive adsorption was also used, from which the approximate imprinting factor was 2. The cavity shape generated during the production of the imprinted silica dictates the adsorption behavior, not the magnitude of the surface area.
Departamento de Engenharia Química-Universidade Federal do Rio Grande do Sul Rua Eng. Luis Englert s/n, Porto Alegre -RS, Brazil.
Cícero
C
de Coelho Escobar
João Henrique Zimnoch
JH
dos Santos
D000327:Adsorption; D005782:Gels / Q000138:chemical synthesis / Q000737:chemistry*; D054802:Molecular Imprinting; D012235:Rhodamines / Q000737:chemistry*; D012822:Silicon Dioxide / Q000138:chemical synthesis / Q000737:chemistry*; D013499:Surface Properties
D005782:Gels; D012235:Rhodamines; D012822:Silicon Dioxide; C029773:rhodamine B
Molecular imprinting; Silica; Small-angle X-ray scattering; Sol-gel