The adsorption behavior of four bile salt species on activated carbon in water at 30 degrees C

Adsorption behavior onto activated carbon was examined for four bile salt species: sodium deoxycholate (NaDC), sodium chenodeoxycholate (NaCDC), sodium ursodeoxycholate (NaUDC) and sodium cholate (NaC) in tetraborate-carbonate buffer solution (pH 10.0) at 30 degrees C. The isotherms obtained for all the species outwardly exhibited Langmuir-type adsorption and enabled us to construct Langmuir plots from which the maximum adsorption amounts of monolayer, N-m, were determined. The decreasing order of N-m was found to be NaUDC > NaCDC > NaDC > NaC. Interestingly, this is very different from that found from adsorption onto graphite (NaDC > NaCDC > NaC > NaUDC), especially for NaUDC, indicating that more complicated factors affect the adsorption of the respective bile salts onto porous adsorbent than onto graphite with a simple surface.