ABSTRACT
234The equilibrium and kinetics of DNA adsorption on silica, alumina, and hydroxylapatite (HAP) powder as a function of pH and MgCl2 concentration were investigated. The adsorption isotherms of DNA on silica, alumina, and HAP were fitted to Langmuir model better than Freundlich model and Dubinin–Radushkevich model. Higher correlation coefficients were obtained with pseudo-second-order model than the pseudo-first-order reaction model in adsorption kinetics of DNA. The DNA adsorption to the external surface of the particles was very fast kinetically and accomplished within about 15 min. After that, intraparticle diffusion mechanism becomes dominant. Intraparticle diffusion coefficient decreased significantly in the order of alumina, silica, and HAP. The kinetic models, reaction, and diffusion models showed that adsorption at the external surface was dominant at initial stages of the DNA adsorption and it was followed by slower intraparticle diffusion.
