Detergency effect of trisodium phosphate on the Removal of bovine serum albumin from alumina surfaces during caustic alkali cleaning

摘要

The detergency effect of trisodium phosphate (Na_3PO_4) on the removal of irreversibly adsorbed bovine serum albumin (BSA) from alumina (Al_2O_3) particles during cleaning with 0.05 M NaOH solution was kinetically studied. The desorption curve of BSA, obtained by plotting the logarithm of the amount of residual BSA against cleaning time, during cleaning with the NaOH solution with and without Na_3PO_4 could be apparently reduced to the sum of two straight lines with different slopes. This fact suggested that two species of BSA, i.e., a faster-desorbing species (BSA~f) and a slower-desorbing species (BSA~s), were present on A12O3 surfaces and desorbed according to a first-order process. The first-order desorption rate constant (k~s) of BSAS obtained from cleaning with the NaOH solution alone was approximately 56-fold lower than that (k~f) of BSA~f. The addition of Na_3PO_4 to the NaOH solution had no influence on the desorption of BSA~f, whereas it accelerated the desorption of BSA~s, with an approximately 7-fold increase in the k~s. Potentiometric titration showed that phosphate ions were adsorbed on Al_2O_3 surfaces after cleaning with the NaOH solution containing Na_3PO_4. The results indicated that hydroxide ion and phosphate ions could displace the sfower-desorbing BSA~s species at Al_2O_3-water interfaces in a synergistic manner.