摘要
采用Wilhelmy吊片法测定一定浓度的丝胶溶液在不同pH条件下的动态表面张力,通过数学经验公式分析动态吸附数据,从吸附模型、吸附分子面积和吸附速率等方面,说明丝胶溶液的动态表面吸附有扩散和动力学吸附2个过程。在不同pH条件下,以丝胶溶液的动态表面压p对吸附时间t,动态表面张力tγ对lgt,以及ln(dp/dt)对p作图,根据经验公式推导出丝胶溶液表面张力下降一半时的时间t1/2、丝胶蛋白质分子吸附控制参数n,丝胶分子在界面上初始渗透和固定时所占面积ΔA1、以及在界面上重排和再取向时所占面积ΔA2。结果表明:丝胶蛋白质分子的吸附过程是扩散动态吸附;在表面上吸附的丝胶蛋白质分子的构象转变存在2个动态过程,即在界面上的分子发生初始渗透和固定阶段,以及吸附在表面上的分子发生重排和再取向阶段;丝胶溶液的pH值影响动态表面张力和分子吸附面积;在pH值低于丝胶等电点时,丝胶分子在界面初始吸附和重排面积较小,动态表面张力较高,表面吸附速度较慢,当pH值高于等电点,表面张力变小,吸附速度加快,丝胶在界面吸附的分子面积变大。
The dynamic surface tensions of sericin solutions at a given concentration and different pH values were measured by Wilhelmy plate method. Such curves were plotted according to the dynamic surface tension （γt） data in different pH, as surface pressure p versus adsorption time t, the relationship between surface pressure and time, r1 - lgt, and In （dp/dt）- p. The curves were analyzed by using some experiential expressions to elucidate the dynamic adsorption behavior, through which the adsorption parameters were deduced of adsorption half-time （t1/2, the time required for surface tension decreasing to the half of the equilibrium value）, the constant controlling adsorption mode （ n ）, the mean molecule area of the molecule occupied at the interface both in initial penetrated and anchored state （△A1） and in rearranged and reoriented state （△A2）. The results indicated that the adsorption process of sericin protein is attributed to a model of diffusion-controlled adsorption kinetics. The conformational transformation of sericin protein molecules adsorbed at the surface undergoes two dynamic steps. The first is initial penetration and anchoring of the molecule from aqueous solution to the surface, and the other is the rearrangement and reorientation of the adsorbed molecule at the interface. The pH value of sericin solution has influences on the dynamic surface tension and the adsorbed molecule area. When pH value of sericin solution is smaller than the equipotential point of sericin protein, △A1 and △A2 are smaller; the dynamic surface tension is higher; and the adsorption rate becomes slower, in comparison with those in the pH value higher than the equipotential point.
出处
《纺织学报》
EI
CAS
CSCD
北大核心
2007年第5期18-22,共5页
Journal of Textile Research
基金
国家自然科学基金资助项目(50673062)
关键词
丝胶
动态表面张力
吸附
分子面积
sericin
dynamic surface tension
adsorption
mean molecular area
