溶剂浸渍树脂吸着螺旋霉素的动力学模型研究

Kinetic Studies of Solvent Impregnated Resins for Sorption of Spiramycin

本文根据颗粒扩散控制机制,认为溶剂萃取过程和固体内表面的吸附同时发生,建立了有限浴条件下溶剂浸溃树脂吸着螺旋霉素的动力学模型.浸渍树脂静态吸附螺旋霉素的计算值与实验值接近,得到螺旋霉素在浸渍树脂内的有效扩散系数为3.7×10^(-12)～29.4×10^(-12)m^2/s.线性吸附等温线条件下的分析解与非线性条件下的数值解比较,表明线性假设能较好地反映实际过程.

Solvent impregnated resins (SIR) as extractants evenly dispersed in a solid polymeric medium are used to separate spiramycin, a macrolide antibiotic. In this paper a particle-diffusion control mathematical model based on linear adsorption isotherm on the inner surface of SIR is developed and its analytical solution under the condition of finite fluid volume can be expressed as follows: where u(t) is referred to as equilibrium fraction of spiramycin, sn are the roots of the equation: snctg sn = 1 + sn2/(3ω), τ is dimensionless time, and ω is a characteristic constant depending on the properties of both SIR itself and the bulk solution of spiramycin. Freundlich adsorption isotherm is also used for the differential equation of diffusion in order to modify the linear type isotherm and its numerical solution is calculated by using finite difference scheme in steps of time and radius. Batch experimental results showed good agreement of the theoretical bulk spiramycin concentration history calculated from the analytical solution with the real values measured. The effective diffusion coefficients of spiramycin were estimated in the range of 3.7× 10-12-29.4 × 10-12 m/s for Amberlite XAD-4 resin impregnated with amyl acetate. The differences between analytical solutions with respect to linear isotherm and the relevant numerical solutions with respect to nonlinear isotherm were within the range of experimental errors indicating that the assumption of linear isotherm is a good approach to the practical process.