Protein adsorption separation using glass fiber membranes modified with short-chain organosilicon derivatives

Porous glass fiber membranes were modified with short-chain organosilicon derivatives to prepare hydrophobic membranes in this study. The organosilicon derivatives tested were octyltriethoxysilane (OTES), butyltrichlorosilane (BTCS), octyldimethylchlorosilane (ODCS), and butyldimethylchlorosilane (BDCS). Based on the contact angle and elemental analysis measurements, both the contact angle value and the increased carbon content were found in the following order: OTES > BTCS > ODCS > BDCS. The increased carbon content for the OTES-modified membrane was 28 μg carbon/cm2, about 0.29 μmol immobilized OTES/cm2. In the batch process, the order of adsorption capacity for both lysozyme and conalbumin is also: OTES > BTCS > ODCS > BDCS. Moreover, lysozyme exhibited higher adsorption capacity than conalbumin in all the cases. In the flow process, the load of 0.1 mg lysozyme and 0.1 mg conalbumin could be totally adsorbed onto one piece of 47 mm OTES-modified membrane. Both proteins were clearly separated in the two-step elution stage, where 98% lysozyme was recovered by 70% acetonitrile and then 75% conalbumin was recovered by 70% isopropanol.