Effect of Pore-size of Mesoporous SBA-15 on Adsorption of Bovine Serum Albumin and Lysozyme Protein

In this paper, the effects of pore-size of SBA-15 on the adsorption kinetics and equilibrium of large protein molecules Bovine serum albumin (BSA) and lysozyme (LYS) have been investigated. The mesoporous molecular sieve SBA-15 with six different pore sizes were synthesized with P123 triblock copolymer as the template agent, and 1,3,5-trimethylbenzene (TMB) and isopropyl alcohol as the pore-expanding agent. The samples were characterized by N2 adsorption/desorption, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD). It is found that BSA and LYS were adsorbed rapidly on SBA-15 materials with large pores. The BSA adsorption capacity of sieve with the pore diameter of 21.4 nm reached 500 mg·g−1 within 25 minutes. However, if the pore diameter was smaller than 14 nm, the BSA adsorption capacity of the sieve was only about 220 mg·g−1. The adsorption equilibrium data fits in the Langmuir model, where the coefficient of effective use of specific area of mesoporous molecular sieve was found to be 0.03, 0.18, 0.37 and 0.48, corresponding to the pore diameter of 10.1 nm, 13.2 nm, 15.4 nm and 21.4 nm, respectively. The equilibrium loading amount of LYS on SBA-15 materials with pore size of 15.4 nm could be up to 1000 mg·g−1. The coefficient of effective use of surface area of mesoporous molecular sieve with diameter of 3.9 nm, 7.4 nm, 10.1 nm, 13.2 nm and 15.4 nm was 0.10, 0.47, 0.56, 0.71 and 0.79, respectively. It is also noted that greater pore size of mesoporous molecular sieve would lead to a higher coefficient of effective use of surface area.