The effect of structure modifying agents in the SBA-15 for its application in the biomolecules adsorption

• Published in: Microporous and mesoporous materials Vol. 232; pp. 53 - 64
• Main Authors: Santos, Sandra M.L., Cecilia, Juan A., Vilarrasa-García, Enrique, Silva Junior, Ivanildo J., Rodríguez-Castellón, Enrique, Azevedo, Diana C.S.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 15-09-2016
• Subjects: Adsorption; Cellulase; Foams; Mesoporous silica; Protein; Separation; Foams; Separation; Adsorption; Cellulase; Mesoporous silica; Protein
• ISSN: 1387-1811; 1873-3093
• DOI: 10.1016/j.micromeso.2016.06.004

The traditional mesoporous silica (SBA-15) was synthesized by hydrothermal route. The swelling agents 1,3,5-trymethylbenzene (TMB) and heptane were used to expand the pore size and fluoride (NH4F) was used to modify the length of the pores, leading to porous silicas with different textural properties. The adsorbents, identified as SBA-15 (S), SBA-15 (S1) (TMB), SBA-15 (S2) (TMB and NH4F) and SBA-15 (S3) (NH4F and heptane), were characterized regarding their texture, mesoscopic ordering and chemical surface and finally their adsorption capacity was evaluated using three model biomolecules (Bovine Serum Albumin – BSA, Lysozyme – LYS and Cellulase – CEL). Adsorption behavior of BSA, LYS and CEL onto these SBA-15 samples was investigated by batch experiments at 25 °C. Highest biomolecule uptake obtained for S2 and S3 were attributed to the larger pore diameter, shorter channel length and the formation of interparticle voids, which provides easier access of these biomolecules to the surface of the adsorbent and minimized the diffusion problems. All cellulase adsorption isotherms followed Henry’s Law. The adsorption capacity of cellulase in S2 was 250 mg/g for a liquid-phase equilibrium concentration of 6 mg/mL, while BSA and LYS adsorption isotherms were well fit by the Langmuir model and the maximum adsorption capacities were 581 and 786 mg/g, respectively.
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•Ammonium fluoride in hydrothermal synthesis of SBA-15 leads to short disordered mesochannels.•Adsorption capacity of the three target biomolecules is related to average pore size.•BSA adsorption and diffusion is enhanced in MCFs with average pore sizes of nearly 20 nm.•Small biomolecules diffuse indistinctively in either ordered SBA-15 or mesocellular foams.