Multi-component models for competitive equilibrium adsorption of 4″-O-isovalerylspiramycin II and III

The equilibrium adsorption experiments were carried out to investigate the effects of pH and temperature on the competitive adsorption of 4″-O-isovalerylspiramycin Ⅱ and Ⅲ in aqueous solutions onto the macroporous resin HZ820.The binary competitive adsorption behavior of 4″-O-isovalerylspiramycin Ⅱ and Ⅲ was described by means of the extended Langmuir,Langmuir-Freundlich and Jovanovic-Freundlich models,among which the extended Langmuir-Freundlich adsorption model gave the best competitive isotherm fits for both 4″-O-isovalerylspiramycin Ⅱ and Ⅲ.The selectivities and adsorption capacities of HZ820 for 4″-O-isovalerylspiramycin Ⅱ and Ⅲ were also studied.The result shows that the adsorption capacities of 4″-O-isovalerylspiramycin Ⅱ and Ⅲ increase with increasing pH and temperature,respectively.The selectivity increases with temperature rise,and reaches a maximum value as pH is increased to 6.5.