Batch uptake of lysozyme: Effect of solution viscosity and mass transfer on adsorption

In this study, solid-phase adsorption by macroporous acid hyper-diffusive r esins was investigated in a batch uptake adsorption system to quantify soli d-phase diffusion rates as a function of bulk phase viscosity. The performa nce of chromatographic resins used for adsorption of proteins is dependent on several factors including solid and liquid-phase diffusivity, boundary l ayer mass transfer, and intraparticle mass transfer effects. Understanding these effects is critical to process development and optimization of both p acked and fluidized bed adsorption systems. The macroporous resin used here was Streamline SP, and the hyper-diffusive resin was S-HyperD LS. Both hav e been frequently used in fluidized bed adsorption of proteins; however, fa ctors that affect uptake rates of these media are not well quantified. Adso rption isotherms were well represented by an empirical fit of a Langmuir is otherm. Solid-phase diffusion coefficients obtained from simulations were i n agreement with other models for macroporous and hyper-diffusive particles . S-HyperD LS in the buffer system had the highest uptake rate, but increas ed bulk phase viscosity decreased the rate by approximately 50%. Increases in bulk phase viscosity increased film mass transfer effects, and uptake wa s observed to be a strong function of the film mass transfer coefficient. U ptake by Streamline SP particles was slower than S-HyperD in buffer, due to a greater degree of intraparticle mass transfer resistance. The effect of increased film mass transfer resistance coupled with intraparticle mass tra nsfer resistances at an increased bulk phase viscosity resulted in a decrea se of 80% in the uptake rate by Streamline SP relative to S-HyperD.