Adsorptien of Chondroitin-6-sulfate Anion and Concomitant Incongruent Dissolution of Calcium Oxalate Monohydrate

Abstract

Adsorption of sodium chondroitin-6-sulfate(Na2Chs) by calcium oxalate monohydrate(CaOx)was studied. Its adsorption isotherm was of high affinity type. The adsorption amount increased with an added concentration of NaC1 or CaC12, while it decreased with that of sodium oxalate. Dissolution behavior of Ox2- and Ca2+ from CaOx was incongruent (Fig.5). Ox2- was released in part by the mechanism of anion exchange with adsorbate Chs 2-. Released Ca2+ was partly captured by Ghs2- present in a mother solution, which played a role of reservoir for Ca2+. However, it was shown by the dialysis method (Fig.4) that the incongruent dissolution of CaOx is restricted through the solubility product (activity product, K. ), which was kept constant over the range of studied concentration of Na2Chs (T able 1)although the adsorption amount and degree of incongruence increased with an added concentration of Na2Chs.