A convenient route to synthesize SBA-15 rods with tunable pore length for lysozyme adsorption

Highly ordered SBA-15 rods with tunable length and width have been synthesized by using nonionic surfactant P123 (EO20PO70EO20) as a structure-directing agent without any additives. SBA-15 rods with varying lengths (0.6–3.0 μm) and widths (0.26–0.40 μm) were tuned by simply adjusting the HCl concentration in the range of 0.5–2.5 M. The acidity was identified to be the key factor affecting the growing manner of the rod-like particles. It was found that the length of these SBA-15 rods decreased with the increase of the HCl concentration in the synthetic mixture, while the width increased slightly. Based on our results, a possible mechanism for the effect of the HCl concentration on the growing manner of the rod-like particles was proposed. Furthermore, adsorption of lysozyme (LYS) on these SBA-15 rods was investigated and the results showed that the shorter rods with shorter pore length demonstrated very rapid LYS adsorption (<10 min to reach equilibrium) and high adsorption capacity (up to 835 mg g−1). This work illustrates that this route is a simple, flexible, reproducible synthesis of SBA-15 rods with tunable pore length. More importantly, it is revealed that the short pore SBA-15 rods with improved pore accessibility can greatly accelerate the adsorption rate and increase the adsorbed amount of the enzyme during the adsorption process.

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► Pore length tunable SBA-15 rods were achieved by tuning the acidity no additives.
► Acidity affects the growing manner of the rod-like particles.
► Short pore length exhibited rapid adsorption rate and high adsorption capacity.